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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2016	Apr. 29, 2016
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q1
Trading Symbol	ETRM
Entity Registrant Name	EnteroMedics Inc
Entity Central Index Key	0001371217
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		9,254,451

Consolidated Balance Sheets - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 11,153,525	$ 7,927,240
Accounts receivable	55,000	57,928
Inventory	1,868,206	1,686,324
Prepaid expenses and other current assets	873,531	831,495
Total current assets	13,950,262	10,502,987
Property and equipment, net	298,447	326,296
Other assets	606,291	757,802
Total assets	14,855,000	11,587,085
Current liabilities:
Current portion of convertible notes payable	5,639,752	717,391
Accounts payable	261,447	172,050
Accrued expenses	3,483,280	3,595,415
Accrued interest payable		1,172
Total current liabilities	9,384,479	4,486,028
Convertible notes payable, less current portion (net of discounts of $533,110 and $149,340 at March 31, 2016 and December 31, 2015, respectively)	5,116,248	549,791
Common stock warrant liability	1,613,560	2,877,817
Total liabilities	16,114,287	7,913,636
Commitments and contingencies (note 5)
Stockholders' equity:
Common stock, $0.01 par value; 150,000,000 and 13,333,333 shares authorized at March 31, 2016 and December 31, 2015, respectively; 8,499,651 and 7,163,820 shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively	84,997	71,638
Additional paid-in capital	283,645,016	281,182,349
Accumulated deficit	(284,989,300)	(277,580,538)
Total stockholders' (deficit) equity	(1,259,287)	3,673,449
Total liabilities and stockholders' equity	$ 14,855,000	$ 11,587,085

Consolidated Balance Sheets (Parenthetical) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Convertible notes payable, less current portion, discounts	$ 533,110	$ 149,340
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	13,333,333
Common stock, shares issued	8,499,651	7,163,820
Common stock, shares outstanding	8,499,651	7,163,820

Consolidated Statements of Operations - USD ($)	3 Months Ended
Consolidated Statements of Operations - USD ($)	Mar. 31, 2016	Mar. 31, 2015
Sales	$ 72,000
Cost of goods sold	40,135
Gross profit	31,865
Operating expenses:
Selling, general and administrative	6,141,177	$ 4,727,519
Research and development	1,432,381	2,236,606
Total operating expenses	7,573,558	6,964,125
Operating loss	(7,541,693)	(6,964,125)
Other income (expense):
Interest income	1,691	867
Interest expense	(1,149,294)	(214,546)
Change in value of convertible notes payable	(499,568)
Change in value of warrant liability	1,779,414
Other, net	688	3,781
Net loss	$ (7,408,762)	$ (7,174,023)
Net loss per share - basic and diluted	$ (0.94)	$ (1.48)
Shares used to compute basic and diluted net loss per share	7,840,992	4,849,061

Consolidated Statements of Comprehensive Loss - USD ($)	3 Months Ended
Consolidated Statements of Comprehensive Loss - USD ($)	Mar. 31, 2016	Mar. 31, 2015
Net loss	$ (7,408,762)	$ (7,174,023)
Comprehensive loss	$ (7,408,762)	$ (7,174,023)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net loss	$ (7,408,762)	$ (7,174,023)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	39,393	48,651
Stock-based compensation	1,092,488	1,372,076
Amortization of commitment fees, debt issuance costs and original issue discount	815,421	165,291
Change in value of convertible notes payable	499,568
Change in value of warrant liability	(1,779,414)
Change in operating assets and liabilities:
Accounts receivable	2,928	1,334
Inventory	(181,882)	(145,778)
Prepaid expenses and other current assets	(42,036)	(41,313)
Other assets	(87,520)	(138,417)
Accounts payable	89,397	(347,163)
Accrued expenses	(112,135)	642,993
Accrued interest payable	174,148	(4,302)
Net cash used in operating activities	(6,898,406)	(5,620,651)
Cash flows from investing activities:
Purchases of property and equipment	(11,544)	(18,656)
Net cash used in investing activities	(11,544)	(18,656)
Cash flows from financing activities:
Proceeds from sale of common stock and warrants for purchase of common stock		6,651,931
Common stock financing costs	(14,000)	(199,557)
Proceeds from convertible notes payable	11,000,000
Repayments on convertible notes payable	(404,762)
Repayments on notes payable		(1,000,000)
Debt issuance costs	(445,003)
Net cash provided by financing activities	10,136,235	5,452,374
Net increase (decrease) in cash and cash equivalents	3,226,285	(186,933)
Cash and cash equivalents:
Beginning of period	7,927,240	11,619,167
End of period	11,153,525	11,432,234
Supplemental disclosure:
Cash paid for interest	163,152	$ 53,556
Noncash investing and financing activities:
Conversion of convertible notes and interest payable	$ 1,397,538

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2016

Summary of Significant Accounting Policies

(1) Summary of Significant Accounting Policies

Description of Business

EnteroMedics Inc. (the Company) develops and sells implantable systems to treat obesity, metabolic diseases and other gastrointestinal disorders. The Company was incorporated in the state of Minnesota on December 19, 2002 and was reincorporated in Delaware on July 22, 2004. The Company is headquartered in St. Paul, Minnesota. In January 2006, the Company established EnteroMedics Europe Sárl, a wholly-owned subsidiary located in Switzerland.

The Company’s board of directors and stockholders approved a 1-for-15 reverse split (the Reverse Stock Split) of the Company’s outstanding common stock that became effective after trading on January 6, 2016. The Reverse Stock Split did not change the par value of the Company’s stock or the number of preferred shares authorized by the Company’s Fifth Amended and Restated Certificate of Incorporation. An amendment to the Certificate of Incorporation was also approved in connection with the Reverse Stock Split to increase the number of shares of the Company’s common stock authorized for issuance to 150 million shares, effective immediately after the Reverse Stock Split on January 6, 2016. All share and per share amounts have been retroactively adjusted to reflect the Reverse Stock Split for all periods presented.

Risks and Uncertainties

The Company is focused on the design and development of medical devices that use neuroblocking technology to treat obesity, metabolic diseases and other gastrointestinal disorders and currently has approvals to commercially launch the Maestro Rechargeable System in the United States and in Australia, the European Economic Area and other countries that recognize the European CE Mark. The Company has devoted substantially all of its resources to recruiting personnel, developing its product technology, obtaining patents to protect its intellectual property and raising capital, and has recently commenced commercial operations in the United States deriving revenues from its primary business activity in 2015.

The Company’s products require approval from the U.S. Food and Drug Administration (FDA) or corresponding foreign regulatory agencies prior to commercial sales. The Company received FDA approval on January 14, 2015 for vBloc Therapy, delivered via the Maestro Rechargeable System, and has begun a controlled commercial launch at select centers in the United States. The Maestro Rechargeable System has also received CE Mark and is listed on the Australian Register of Therapeutic Goods (ARTG).

The medical device industry is characterized by frequent and extensive litigation and administrative proceedings over patent and other intellectual property rights. Whether a product infringes a patent involves complex legal and factual issues, the determination of which is often difficult to predict, and the outcome may be uncertain until the court has entered final judgment and all appeals are exhausted. The Company’s competitors may assert that its products or the use of the Company’s products are covered by U.S. or foreign patents held by them.

The Company’s activities are subject to significant risks and uncertainties, including the ability to obtain additional financing, and there can be no assurance that the Company will be successful in obtaining additional financing on favorable terms, or at all. If adequate funds are not available, the Company may have to delay development or commercialization of products or license to third parties the rights to commercialize products or technologies that the Company would otherwise seek to commercialize.

Basis of Presentation

The Company has prepared the accompanying condensed consolidated financial statements in conformity with accounting principles generally accepted in the United States of America. The Company’s fiscal year ends on December 31.

The accompanying condensed consolidated financial statements and notes thereto are unaudited. In the opinion of the Company’s management, these statements include all adjustments, which are of a normal recurring nature, necessary to present a fair presentation. Interim results are not necessarily indicative of results for a full year. The condensed consolidated balance sheet as of December 31, 2015 was derived from audited consolidated financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America. The information included in this Form 10-Q should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2015.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.

Principles of Consolidation

The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary. All intercompany transactions and accounts have been eliminated in consolidation.

Fair Value of Financial Instruments

Carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued liabilities approximate fair value due to their short maturities. The Company’s common stock warrants are required to be reported at fair value and the Company has elected to report its senior amortizing convertible notes at fair value. The fair values of common stock warrants and investments in debt and equity securities, if any, are disclosed in Note 3. The fair value of the Company’s senior amortizing convertible notes is disclosed in Notes 3 and 7.

Common Stock Warrant Liability

Common stock warrants that were issued in connection with the July 8, 2015 public offering and the November 9, 2015 and January 11, 2016 senior amortizing convertible notes are classified as a liability in the condensed consolidated balance sheets, as the common stock warrants issued provide for certain anti-dilution protections in the event shares of common stock or securities convertible into shares of common stock are issued below the then-existing exercise price. The fair value of these common stock warrants is re-measured at each financial reporting period and immediately before exercise, with any changes in fair value being recognized as a component of other income (expense) in the condensed consolidated statements of operations.

Cash and Cash Equivalents

The Company considers highly liquid investments generally with maturities of 90 days or less when purchased to be cash equivalents. Cash equivalents are stated at cost, which approximates market value. The Company’s cash equivalents are primarily in money market funds and certificates of deposit. The Company deposits its cash and cash equivalents in high-quality credit institutions.

Short-Term Investments

The Company considers all investments with maturities greater than three months and less than one year at the time of purchase as short-term investments and classifies them as either available for sale or held to maturity. The Company also considers certain investments with maturities greater than one year but which are also held for liquidity purposes and are available for sale as short-term investments.

Available-for-sale securities are carried at fair value based on quoted market prices, with the unrealized gains and losses included in other comprehensive income within stockholders’ equity in the condensed consolidated balance sheets. Realized gains and losses and declines in value judged to be other than temporary on available-for-sale securities are included in interest and other income. Interest and dividends on securities classified as available for sale are included in interest income. The cost of securities sold is based on the specific identification method.

Short-term investments in debt securities which the Company has the positive intent and ability to hold to maturity are reported at cost, adjusted for premiums and discounts that are recognized in interest income, using the interest method, over the period to maturity. Unrealized losses on held-to-maturity securities reflecting a decline in value determined to be other than temporary are charged to income.

Inventory

The Company accounts for inventory at the lower of cost or market and records any long-term inventory as other assets in the condensed consolidated balance sheets.

Property and Equipment, Net

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation of property and equipment is computed using the straight-line method over their estimated useful lives of five to seven years for furniture and equipment and three to five years for computer hardware and software. Leasehold improvements are amortized on a straight-line basis over the lesser of their useful life or the term of the lease. Upon retirement or sale, the cost and related accumulated depreciation or amortization are removed from the condensed consolidated balance sheets and the resulting gain or loss is reflected in the condensed consolidated statements of operations. Repairs and maintenance are expensed as incurred.

Impairment of Long-Lived Assets

The Company evaluates its long-lived assets for impairment by comparison of the carrying amounts to future net undiscounted cash flows expected to be generated by such assets when events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s fair value or estimates of future discounted cash flows. The Company has not identified any such impairment losses to date.

Income Taxes

Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carry-forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance for deferred income tax assets is recorded when it is more likely than not that some portion or all of the deferred income tax assets will not be realized. The Company has provided a full valuation allowance against the gross deferred tax assets. The Company’s policy is to classify interest and penalties related to income taxes as income tax expense in the condensed consolidated statements of operations.

Medical Device Excise Tax

On January 14, 2015, the Company received FDA approval for vBloc Therapy, delivered via the Maestro Rechargeable System, and starting in the second quarter of 2015 revenues were generated from sales in the United States. As a result, the Company is now required to pay a quarterly Medical Device Tax which is a part of the Affordable Care Act, which imposes a 2.3% excise tax on the sale of certain medical devices by device manufactures, producers or importers. The excise tax was effective on sales of devices made after December 31, 2012. The Company records the Medical Device Tax as an operating expense in the condensed consolidated statements of operations. A moratorium was placed on the Medical Device Tax for 2016 and 2017.

Comprehensive Loss

Comprehensive loss is defined as the change in equity of a company during a period from transactions and other events and circumstances excluding transactions resulting from investment owners and distributions to owners. There was no difference from reported net loss for the three months ended March 31, 2016 and 2015.

Revenue Recognition

Revenue is recognized when persuasive evidence of an arrangement exists, title or risk of loss has passed, the selling price is fixed or determinable and collection is reasonably assured. Products are sold through direct sales or medical device distributors and revenue is recognized upon sale to a bariatric center of excellence or a medical device distributor when no right of return or price protection exists. Terms of sales to international distributors are generally EXW, reflecting that goods are shipped “ex works,” in which risk of loss is assumed by the distributor at the shipping point. A provision for returns is recorded only if product sales provide for a right of return. No provision for returns was recorded for the three months ended March 31, 2016 and 2015, as the product sales recorded did not provide for rights of return.

Research and Development Expenses

Research and development expenses are charged to expense as incurred. Research and development expenses include, but are not limited to, product development, clinical trial expenses, including supplies, devices, explants and revisions, quality assurance, regulatory expenses, payroll and other personnel expenses, materials and consulting costs.

Net Loss Per Share

Basic net loss per share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per share is based on the weighted-average common shares outstanding during the period plus dilutive potential common shares calculated using the treasury stock method. Such potentially dilutive shares are excluded when the effect would be to reduce a net loss per share. The Company’s potential dilutive shares, which include outstanding common stock options and warrants, have not been included in the computation of diluted net loss per share for all periods as the result would be anti-dilutive.

The following table sets forth the computation of basic and diluted net loss per share for the three months ended March 31, 2016 and 2015:


	Three months ended March 31,
	2016			2015
Numerator:
Net loss	$	(7,408,762	)	$	(7,174,023	)

Denominator for basic and diluted net loss per share:
Weighted-average common shares outstanding		7,840,992			4,849,061

Net loss per share—basic and diluted	$	(0.94	)	$	(1.48	)

The following table sets forth the potential shares of common stock that are not included in the calculation of diluted net loss per share because to do so would be anti-dilutive as of the end of each period presented:


	March 31,
	2016		2015
Stock options outstanding		1,953,859		948,675
Warrants to purchase common stock		4,476,839		1,613,133

Recently Issued or Adopted Accounting Standards

In March 2016, the Financial Accounting Standards Board (FASB) issued Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (Accounting Standards Update No. 2016-09 (ASU 2016-09)). ASU 2016-09 modifies several aspects of the accounting for share-based payment awards, including income tax consequences, and classification on the statement of cash flows. This guidance will be effective for interim and annual reporting periods beginning after December 15, 2016. The Company is currently evaluating the impact of adopting ASU 2016-09 on its consolidated financial statements.

In May 2014, FASB issued Revenue from Contracts with Customers, Topic 606 (Accounting Standards Update No. 2014-09 (ASU 2014-09)), which provides a framework for the recognition of revenue, with the objective that recognized revenues properly reflect amounts an entity is entitled to receive in exchange for goods and services. This guidance will be effective for interim and annual reporting periods beginning after December 15, 2017. The Company is currently evaluating the impact of adopting ASU 2014-09 on its consolidated financial statements.

There have been no other significant changes in recent accounting pronouncements during the three months ended March 31, 2016 as compared to the recent accounting pronouncements described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015.

Liquidity and Management's Plans

3 Months Ended

Mar. 31, 2016

Liquidity and Management's Plans

(2) Liquidity and Management’s Plans

The accompanying condensed consolidated financial statements have been prepared assuming the Company will continue as a going concern. The Company has financed its operations to date principally through the sale of equity securities, debt financing and interest earned on investments. As of March 31, 2016, the Company had $11.2 million of cash and cash equivalents to fund its anticipated operations through 2016. On November 4, 2015, the Company entered into a securities purchase agreement (the Purchase Agreement) with institutional investors to issue $25.0 million of senior amortizing convertible notes (the Notes) along with the accompanying warrants. $1.5 million of the Notes was funded at the first closing on November 9, 2015. An additional $11.0 million of the Notes was funded at the second closing on January 11, 2016. Pursuant to an amendment to the Purchase Agreement (the Amendment) entered into on May 2, 2016, the remaining $12.5 million will be funded at two separate closings, with $6.25 million of the Notes funded on May 2, 2016 and the remaining $6.25 million to be funded at a later date. Additionally, the Company has agreed that it will not, for a period of one year after the first closing, issue any further securities, other than certain excluded securities. The Company’s anticipated operations include plans that consider the controlled commercial launch of vBloc Therapy, delivered via the Maestro Rechargeable System, which was approved by the FDA on January 14, 2015. The Company believes that it has the flexibility to manage the growth of its expenditures and operations.

Short-term Investments and Fair Value Measurements

3 Months Ended

Mar. 31, 2016

Short-term Investments and Fair Value Measurements

(3) Short-term Investments and Fair Value Measurements

Fair value of financial assets and liabilities is defined as the price that would be received to sell an asset or transfer a liability in an orderly transaction between market participants at the measurement date. A fair value hierarchy has been established that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are described below:

•

Level 1—Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.

•

Level 2—Quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active or model-derived valuations for which all significant inputs are observable, either directly or indirectly.

•

Level 3—Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable.

The Company’s assets that are measured at fair value on a recurring basis are classified within Level 1 or Level 2 of the fair value hierarchy. The Company does not hold any assets that are measured at fair value using Level 3 inputs. The types of instruments the Company invests in that are valued based on quoted market prices in active markets may include U.S. treasury securities and money market funds. Such instruments are classified by the company within Level 1 of the fair value hierarchy. U.S. treasuries are valued using unadjusted quoted prices for identical assets in active markets that the Company can access.

The types of instruments the Company invests in that are valued based on quoted prices in less active markets, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency include the Company’s U.S. agency securities, commercial paper, U.S. corporate bonds and municipal obligations. Such instruments are classified by the Company within Level 2 of the fair value hierarchy. The Company values these types of assets using consensus pricing or a weighted average price, which is based on multiple pricing sources received from a variety of industry standard data providers (e.g. Bloomberg), security master files from large financial institutions, and other third-party sources. The multiple prices obtained are then used as inputs into a distribution-curve-based algorithm to determine the daily market price.

The Company did not hold any short-term investments classified as available for sale or held to maturity as of March 31, 2016 and December 31, 2015.

The fair value of the Company’s common stock warrant liability is calculated using a Black-Scholes valuation model and is classified as Level 2 in the fair value hierarchy. The common stock warrants issued July 8, 2015 had a fair value of $1,198,689 and $2,759,583 on March 31, 2016 and December 31, 2015, respectively. The common stock warrants issued November 9, 2015 had a fair value of $75,670 and $118,234 on March 31, 2016 and December 31, 2015, respectively. The common stock warrants issued January 11, 2016 had a fair value of $339,201 and $515,157 on March 31, 2016 and January 11, 2016, respectively. The fair value was calculated using the following assumptions:


	July 2015 Warrants						November 2015 Warrants						January 2016 Warrants
	March 31, 2016			December 31, 2015			March 31, 2016			December 31, 2015			March 31, 2016			January 11, 2016
Risk-free interest rates		0.87	%		1.31	%		1.21	%		1.76	%		1.21	%		1.58	%
Expected life		33 months			36 months			55 months			58 months			57 months			60 months
Expected dividends		0	%		0	%		0	%		0	%		0	%		0	%
Expected volatility		91.15	%		97.94	%		91.42	%		86.27	%		90.04	%		85.90	%

The following table summarizes fair value measurements of the senior amortizing convertible notes and the common stock warrants issued in 2015 and during the three months ended March 31, 2016 by level at March 31, 2016:


	Level 1		Level 2		Level 3		Total
Senior amortizing convertible notes	$	—	$	—	$	10,756,000	$	10,756,000
Common stock warrants		—		1,613,560		—		1,613,560

Total	$	—	$	1,613,560	$	10,756,000	$	12,369,560

As of March 31, 2016, the Company converted $1,507,042 of senior amortizing convertible notes principal and interest into shares of common stock. There was a $499,568 loss resulting from the senior amortizing convertible notes recognized in the condensed consolidated statements of operations for the three months ended March 31, 2016.

Inventory

3 Months Ended

Mar. 31, 2016

Inventory

(4) Inventory

From the Company’s inception, inventory related purchases had been used for research and development related activities and had accordingly been expensed as incurred. In December 2011, the Company began receiving ARTG listings for components of the Maestro Rechargeable System from the Australian Therapeutic Goods Administration, with the final components being listed on the ARTG in January 2012. As a result, the Company determined certain assets were recoverable as inventory beginning in December 2011. The Company accounts for inventory at the lower of cost or market and records any long-term inventory as other assets in the condensed consolidated balance sheets. There was approximately $606,000 and $519,000 of long-term inventory, primarily consisting of raw materials, as of March 31, 2016 and December 31, 2015, respectively.

Current inventory consists of the following as of:


	March 31, 2016		December 31, 2015
Raw materials	$	527,471	$	576,898
Work-in-process		1,296,525		1,066,345
Finished goods		44,210		43,081

Inventory	$	1,868,206	$	1,686,324

Commitments and Contingencies

3 Months Ended

Mar. 31, 2016

Commitments and Contingencies

(5) Commitments and Contingencies

Operating Lease

The Company rents its office, warehouse and laboratory facilities under an operating lease, which was originally set to expire on September 30, 2015. On August 25, 2015, the Company entered into an amendment extending the term of the operating lease for three years until September 30, 2018, with monthly base rent ranging from $18,925 to $20,345. Total rent expense recognized for each of the three month periods ended March 31, 2016 and 2015 was $58,905 and $67,718, respectively. At March 31, 2016, future minimum payments under the lease are as follows:


Year ending December 31:
Remaining nine months in 2016	$	172,457
2017		237,749
2018		183,103

	$	593,309

Product Liability Claims

The Company is exposed to product liability claims that are inherent in the testing, production, marketing and sale of medical devices. Management believes any losses that may occur from these matters are adequately covered by insurance, and the ultimate outcome of these matters will not have a material effect on the Company’s financial position or results of operations. The Company is not currently a party to any litigation and is not aware of any pending or threatened litigation that could have a material adverse effect on the Company’s business, operating results or financial condition.

Clinical Trials

The Company is evaluating the Maestro System in human clinical trials, including the EMPOWER trial and ReCharge trial. Both of these clinical trials require patients to be followed out to 60 months. The Company is required to pay for patient follow up visits only to the extent they occur. In the event a patient does not attend a follow up visit, the Company has no financial obligation. The Company is also required to pay for explants or revisions, including potential conversions of ReCharge control devices to active devices, should a patient request or be required to have one during the course of the clinical trials. The Company has no financial obligation unless an explant, revision or conversion is requested or required. Clinical trial costs are expensed as incurred.

Notes Payable

3 Months Ended

Mar. 31, 2016

Notes Payable

(6) Notes Payable

On April 16, 2012, the Company entered into a Loan and Security Agreement (the Loan Agreement) with Silicon Valley Bank (SVB) pursuant to which SVB agreed to make term loans in an aggregate principal amount of up to $20.0 million ($10.0 million of which was not available as the Company did not meet the predefined primary efficacy measures of the ReCharge trial and did not meet certain financial objectives for 2012), on the terms and conditions set forth in the Loan Agreement.

Pursuant to the Loan Agreement, a term loan was funded in the aggregate principal amount of $10.0 million on April 23, 2012, a portion of which was used to repay in full outstanding debt of approximately $4.7 million. The term loan required interest only payments monthly through March 31, 2013 followed by 30 equal payments of principal in the amount of $333,333 plus accrued interest beginning on April 1, 2013 and ending on September 1, 2015, payable monthly. Amounts borrowed under the Loan Agreement bore interest at a fixed annual rate equal to 8.0%. The Company entered into a First Amendment (the First Amendment) to the Loan Agreement on May 9, 2013 pursuant to which the Company and SVB agreed to new financial covenants.

The First Amendment eliminated the financial covenants that required the Company to generate certain minimum amounts of revenue from the sale of its Maestro Rechargeable System and to implant certain minimum numbers of Maestro Rechargeable Systems during cumulative quarterly measurement periods beginning with the period ended March 31, 2013 and ending with the period ended June 30, 2015. It also removed SVB’s ability to require the Company to maintain a restricted cash balance of $7.5 million in an SVB account as a result of the Company not meeting the predefined primary efficacy measures of the ReCharge trial.

The First Amendment added two new financial covenants, one of which required the Company to receive cumulative aggregate net proceeds of at least $5.0 million by November 15, 2013 and $10.0 million by April 15, 2014 from new capital transactions, both of which were fulfilled. The second financial covenant required the Company to maintain a liquidity ratio (unrestricted cash divided by outstanding debt) of at least 1.25:1.00 until it received FDA approval for the Maestro Rechargeable System on January 14, 2015, at which point it was reduced to 0.75:1.00. The First Amendment did not change the interest rate or the amortization structure. A 5.0% final payment fee of $500,000 was due and paid on September 1, 2015. The Company also paid SVB a $187,000 success fee as a result of receiving FDA approval for the Maestro Rechargeable System.

The Company had granted SVB a security interest in all of the Company’s assets, excluding intellectual property except with respect to all license, royalty fees and other revenues and income arising out of or relating to any of the intellectual property and all proceeds of the intellectual property. The Company also had entered into a negative pledge arrangement with SVB pursuant to which it had agreed not to encumber any of its intellectual property without SVB’s prior written consent.

Pursuant to the Loan Agreement, on April 16, 2012, the Company issued SVB a warrant to purchase 7,116 shares of common stock, exercisable for ten years from the date of grant, at an exercise price of $35.10 per share.

The final payment related to the Loan Agreement, as amended, was paid on September 1, 2015.

Senior Amortizing Convertible Notes

3 Months Ended

Mar. 31, 2016

Senior Amortizing Convertible Notes

(7) Senior Amortizing Convertible Notes

On November 4, 2015, the Company entered into the Purchase Agreement to issue and sell to four institutional investors 7% senior amortizing convertible notes due 2017 that are convertible into shares of the Company’s common stock at a price equal to $4.35 per share with an aggregate principal amount of $25.0 million. Each Note was sold with a warrant to purchase a share of common stock (the Warrants) with an exercise price of $4.65 per share. The Company issued and sold Notes and Warrants for aggregate total proceeds of $12.5 million in two separate closings through March 31, 2016 and pursuant to the Amendment, issued and sold Notes and Warrants for aggregate total proceeds of $6.25 million in the third closing, which occurred on May 2, 2016. The Company will issue and sell Notes and Warrants for aggregate total proceeds of $6.25 million in the fourth and final closing.

Description of the Notes

The Notes are payable in monthly installments, accrue interest at a rate of 7.0% per annum from the date of issuance and will mature 24 months after the First Closing (defined below), unless converted or redeemed earlier. The Notes may be repaid, at the Company’s election, in either cash or shares of the Company’s common stock at a discount to the then-current market price. The Notes are also convertible from time to time, at the election of the holders, into shares of the Company’s common stock at an initial conversion price of $4.35 per share. The conversion price was adjusted to $1.09 per share on January 29, 2016, the 16^th trading day following the Reverse Stock Split, per the terms of the Notes.

The holder of each Note has the right to convert any portion of such Note unless the holder, together with its affiliates, beneficially owns in excess of 4.99% of the number of shares of the Company’s common stock outstanding immediately after giving effect to the conversion, as such percentage ownership is determined in accordance with the terms of the Notes. However, any holder may increase or decrease such percentage to any other percentage, but in no event above 9.99%, provided that any increase of such percentage will not be effective until 61 days after providing notice to the Company.

The Company has determined that the conversion feature in the Notes requires bifurcation and liability classification and measurement, at fair value, and requires evaluation at each reporting period. Under Accounting Standards Codification (ASC) 825, Financial Instruments, the FASB provides an alternative to bifurcation and companies may instead elect fair value measurement for the entire instrument, including the debt and conversion feature. The Company has elected the fair value alternative in order to simplify its accounting and reporting of the Notes upon issuance. The fair value of the Warrants is recorded as a discount to the Notes and amortized to interest expense following the effective interest rate method over the term of the Notes.

The first of the four closings (the First Closing) occurred on November 9, 2015. At the First Closing, the Company issued and sold Notes with an aggregate principal amount of $1.5 million, along with Warrants exercisable for 117,520 shares. The fair value of the Warrants issued on November 9, 2015 was determined to be $169,000 using a Black-Scholes valuation model and the following assumptions: (1) dividend yield of 0%; (2) expected volatility of 84.85%; (3) weighted average risk –free interest rate of 1.75%; and (4) expected life of 5.0 years.

The second of the four closings (the Second Closing) occurred on January 11, 2016 after the Company received approval of the offering by the Company’s stockholders and the satisfaction of certain customary closing conditions. At the Second Closing, the Company issued and sold Notes with an aggregate principal amount of $11.0 million, along with Warrants exercisable for 861,842 shares. The fair value of the Warrants issued on January 11, 2016 was determined to be $515,000 using a Black-Scholes valuation model and the following assumptions: (1) dividend yield of 0%; (2) expected volatility of 85.90%; (3) weighted average risk –free interest rate of 1.58%; and (4) expected life of 5.0 years.

The third of the four closings (the Third Closing) occurred on May 2, 2016 after the Company entered into the Amendment. At the Third Closing, the Company issued and sold Notes with an aggregate principal amount of $6.25 million, along with Warrants exercisable for 489,684 shares.

At the final of the four closings (the Fourth Closing) the Company will issue and sell Notes with an aggregate principal amount of $6.25 million, along with Warrants exercisable for 489,682 shares.

On March 31, 2016 and December 31, 2015, the fair value of the outstanding Notes from the First Closing was determined to be $1.2 million and $1.3 million, respectively. On March 31, 2016 and January 11, 2016, the fair value of the outstanding Notes from the Second Closing was determined to be $9.5 million and $9.9 million, respectively. The fair values were calculated using a Binomial Lattice model and the following assumptions:


	November 2015 Notes						January 2016 Notes
	March 31, 2016			December 31, 2015			March 31, 2016			January 11, 2016
Risk-free interest rates		0.68	%		1.11	%		0.68	%		1.01	%
Expected life		1.61 years			1.86 years			1.61 years			1.83 years
Expected dividends		0	%		0	%		0	%		0	%
Expected volatility		65.0	%		57.5	%		65.0	%		60.0	%
Fair value per share of common stock	$	0.97		$	1.95		$	0.97		$	1.33

The following table summarizes the installment amounts and additional conversions by the holders of the Notes issued at the First Closing through March 31, 2016:


	Principal		Interest		Total		Common Shares
Installment amount at December 31, 2015	$	65,217	$	23,651	$	88,868		56,967
Holder conversions during the quarter ended December 31, 2015		18,261		2,375		20,636		13,228

Balance December 31, 2015		83,478		26,026		109,504		70,195
Installment amount at February 29, 2016		65,217		23,681		88,898		91,953
Installment amount at March 31, 2016		65,217		14,827		80,044		88,960
Holder conversions during the quarter ended March 31, 2016		104,784		12,762		117,546		106,684

Balance, March 31, 2016	$	318,696	$	77,296	$	395,992		357,792

The following table summarizes the installment amounts and additional conversions by the holders of the Notes issued at the Second Closing through March 31, 2016:


	Principal		Interest		Total		Common Shares
Installment amount at March 2, 2016	$	404,762	$	149,300	$	554,062		*
Holder conversions during the quarter ended March 31, 2016		987,000		124,050		1,111,050		1,048,167

Balance, March 31, 2016	$	1,391,762	$	273,350	$	1,665,112		1,048,167

*	Cash payments

Description of the Warrants

Each Warrant is exercisable immediately and for a period of 60 months from the date of the issuance of the Warrant. The Warrants entitle the holders of the Warrants to purchase, in aggregate, 1,958,728 shares of the Company’s common stock upon the completion of the Fourth Closing, subject to certain adjustments. The Warrants are initially exercisable at an exercise price equal to $4.65, subject to adjustment on the eighteen month anniversary of issuance, and certain other adjustments. The exercise price and number of shares of common stock issuable on the exercise of the Warrants is subject to adjustment upon the issuance of any shares of common stock or securities convertible into shares of common stock below the then-existing exercise price, with certain exceptions, and in the event of any stock split, reverse stock split, recapitalization, reorganization or similar transaction. The holder of each Warrant does not have the right to exercise any portion of such Warrant if the holder, together with its affiliates, beneficially owns in excess of 4.99% of the number of shares of the Company’s common stock outstanding immediately after giving effect to the exercise, as such percentage ownership is determined in accordance with the terms of the Warrants. However, any holder may increase or decrease such percentage to any other percentage, but in no event above 9.99%, provided that any increase of such percentage will not be effective until 61 days after providing notice to the Company.

The exercise price of the Warrants issued November 9, 2015 was reduced to $1.09 per share on January 29, 2016, the 16^th trading day following the Reverse Stock Split, per the terms of the Warrants. The exercise price of the Warrants issued January 11, 2016 and May 2, 2016 remains $4.65 per share per the terms of the Warrants. All of the Warrants issued with the Notes remain subject to adjustment on the eighteen month anniversary of issuance.

Stock-based Compensation

3 Months Ended

Mar. 31, 2016

Stock-based Compensation

(8) Stock-based Compensation

The fair value method of accounting for share-based payments is applied to all share-based payment awards issued to employees and where appropriate, nonemployees, unless another source of literature applies. When determining the measurement date of a nonemployee’s share-based payment award, the Company measures the stock options at fair value and remeasures such stock options to the current fair value until the performance date has been reached.

Based on the application of these standards, stock-based compensation expense for stock-based awards under the Company’s Amended and Restated 2003 Stock Incentive Plan (the Plan) and inducement grants for the three months ended March 31, 2016 and 2015 was allocated to operating expenses and employees and nonemployees as follows:


	Three months ended March 31,
	2016		2015
Selling, general and administrative	$	839,777	$	1,036,446
Research and development		252,711		335,630

Total	$	1,092,488	$	1,372,076


	Three months ended March 31,
	2016		2015
Employees	$	1,090,192	$	1,387,924
Nonemployees		2,296		(15,848	)

Total	$	1,092,488	$	1,372,076

As of March 31, 2016 there was approximately $5.1 million of total unrecognized compensation costs, net of estimated forfeitures, related to employee unvested stock option awards, which are expected to be recognized over a weighted-average period of 2.57 years.

The estimated grant-date fair values of the stock options were calculated using the Black-Scholes valuation model, based on the following assumptions for the three months ended March 31, 2016 and 2015:


	Employees
	Three months ended March 31,
	2016	2015
Risk-free interest rates	1.16%-1.64%	1.65%-1.80%
Expected life	5.00-6.25 years	6.25 years
Expected dividends	0%	0%
Expected volatility	88.43%-92.24%	110.32%-111.77%


	Nonemployees
	Three months ended March 31,
	2016	2015
Risk-free interest rates	1.11%	0.03%-1.77%
Expected life	4.39 years	0.25-8.51 years
Expected dividends	0%	0%
Expected volatility	92.41%	37.36%-131.49%

Option activity under the Plan for the three months ended March 31, 2016 was as follows:


				Outstanding Options
	Shares Available For Grant			Number of Shares			Weighted- Average Exercise Price
Balance, December 31, 2015		296,579			1,018,752		$	32.83
Shares reserved		—			—			—
Options granted		(53,333	)		53,333			1.07
Options exercised		—			—			—
Options cancelled		14,893			(14,893	)		5.10

Balance, March 31, 2016		258,139			1,057,192		$	31.62

In addition to the stock options granted pursuant to the Plan, the Company has also granted inducement stock options in connection with the appointments of Mr. Gladney to the position of President and Chief Executive Officer on October 28, 2015, Mr. Ansari to the position of Senior Vice President (SVP) of Sales on January 6, 2016, Mr. Delange to the position of SVP of Operations and Business Development on January 18, 2016 and Mr. Hickey to the position of SVP of Marketing and Reimbursement on January 18, 2016. Mr. Gladney was granted an option to purchase 516,666 shares of the Company’s common stock as an inducement grant, with an exercise price of $3.75 per share, the closing price of the Company’s common stock on October 28, 2015. Mr. Delange was granted an option to purchase 166,667 shares of the Company’s common stock as an inducement grant, with an exercise price of $1.38 per share, the closing price of the Company’s common stock on January 18, 2016. Mr. Ansari was granted an option to purchase 106,667 shares of the Company’s common stock as an inducement grant, with an exercise price of $1.31 per share, the closing price of the Company’s common stock on January 19, 2016. Mr. Hickey was granted an option to purchase 106,667 shares of the Company’s common stock as an inducement grant, with an exercise price of $1.32 per share, the closing price of the Company’s common stock on January 22, 2016. Each of the inducement grants will vest as follows: 25% of the shares will vest as of one year from the date of the officer’s employment agreement, and the remaining 75% of the shares will then vest in equal 2.0833% installments each month thereafter for 36 months.

Stock Sales

3 Months Ended

Mar. 31, 2016

Stock Sales

(9) Stock Sales

Sales Agreement—July 2015

On July 8, 2015, the Company closed a public offering, where it sold 2,133,333 units at an aggregate price of $7.50 per unit, for gross proceeds of $16.0 million before deducting estimated offering expenses of approximately $1.4 million, of which $532,000 was assigned to the warrants issued with each unit sold and was recognized immediately as interest expense in the condensed consolidated statements of operations as the warrants are exercisable upon issuance. Each unit consisted of: (A)(i) one share of common stock or (ii) one pre-funded Series C warrant to purchase one share of common stock at an exercise price equal to $7.50 per share (Series C Warrant); and (B) one Series A warrant to purchase one share of common stock at an exercise price initially equal to $9.00 per share (Series A Warrant). Each purchaser of a unit could elect to receive a Series C Warrant in lieu of a share of common stock. No Series C Warrants were issued.

The Series A Warrants are exercisable for a period of 42 months from the closing date of the public offering. The exercise price and number of shares of common stock issuable on the exercise of the Series A Warrants are subject to adjustment upon the issuance of any shares of common stock or securities convertible into shares of common stock below the then-existing exercise price, with certain exceptions, and in the event of any stock split, reverse stock split, recapitalization, reorganization or similar transaction. The holder of the Series A Warrant does not have the right to exercise any portion of the Series A Warrant if the holder, together with its affiliates, would, subject to certain limited exceptions, beneficially own in excess of 9.99% of the Company’s common stock outstanding immediately after the exercise or 4.99% as may be elected by the purchaser.

The exercise price of the Series A Warrants issued July 8, 2015 was reduced to $2.40 per share on November 9, 2015 as a result of the issuance of the Notes and was further reduced to $1.50 per share on December 31, 2015, $0.97 per share on January 29, 2016 and $0.88 on March 30, 2016 after installment payments on the Notes were made.

Sales Agreement—June 2014

On June 13, 2014, the Company entered into a sales agreement with Cowen and Company, LLC (Cowen) to sell shares of the Company’s common stock having aggregate gross sales proceeds of up to $25.0 million, from time to time, through an ATM under which Cowen will act as the Company’s sales agent (the Cowen ATM). The Company will determine, at its sole discretion, the timing and number of shares to be sold under the Cowen ATM. The Company will pay Cowen a commission for its services in acting as agent in the sale of common stock equal to 3.0% of the gross sales price per share of all shares sold through it as agent under the sales agreement. As of March 31, 2016, the Company had sold 367,903 shares under the Cowen ATM at a weighted-average selling price of $20.60 per share for gross proceeds of $7.6 million before deducting offering expenses. There have been no shares sold under the Cowen ATM subsequent to March 31, 2016 through May 10, 2016. The Company is restricted from issuing shares under the Cowen ATM until November 9, 2016 per the terms of the Notes (see Notes 2 and 7).

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2016

Description of Business

Description of Business

Risks and Uncertainties

Risks and Uncertainties

Basis of Presentation

Basis of Presentation

Use of Estimates

Use of Estimates

Principles of Consolidation

Principles of Consolidation

Fair Value of Financial Instruments

Fair Value of Financial Instruments

Common Stock Warrant Liability

Common Stock Warrant Liability

Cash and Cash Equivalents

Cash and Cash Equivalents

Short-Term Investments

Short-Term Investments

Inventory

Inventory

The Company accounts for inventory at the lower of cost or market and records any long-term inventory as other assets in the condensed consolidated balance sheets.

Property and Equipment, Net

Property and Equipment, Net

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets

Income Taxes

Income Taxes

Medical Device Excise Tax

Medical Device Excise Tax

Comprehensive Loss

Comprehensive Loss

Revenue Recognition

Revenue Recognition

Research and Development Expenses

Research and Development Expenses

Net Loss Per Share

Net Loss Per Share

The following table sets forth the computation of basic and diluted net loss per share for the three months ended March 31, 2016 and 2015:


	Three months ended March 31,
	2016			2015
Numerator:
Net loss	$	(7,408,762	)	$	(7,174,023	)

Denominator for basic and diluted net loss per share:
Weighted-average common shares outstanding		7,840,992			4,849,061

Net loss per share—basic and diluted	$	(0.94	)	$	(1.48	)


	March 31,
	2016		2015
Stock options outstanding		1,953,859		948,675
Warrants to purchase common stock		4,476,839		1,613,133

Recently Issued or Adopted Accounting Standards

Recently Issued or Adopted Accounting Standards

Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2016

Computation of Basic and Diluted Net Loss per Share

The following table sets forth the computation of basic and diluted net loss per share for the three months ended March 31, 2016 and 2015:


	Three months ended March 31,
	2016			2015
Numerator:
Net loss	$	(7,408,762	)	$	(7,174,023	)

Denominator for basic and diluted net loss per share:
Weighted-average common shares outstanding		7,840,992			4,849,061

Net loss per share—basic and diluted	$	(0.94	)	$	(1.48	)

Antidilutive Securities


	March 31,
	2016		2015
Stock options outstanding		1,953,859		948,675
Warrants to purchase common stock		4,476,839		1,613,133

Short-term Investments and Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2016

Summary of Fair Value Measurements of Senior Amortizing Convertible Notes and Common Stock Warrants


	Level 1		Level 2		Level 3		Total
Senior amortizing convertible notes	$	—	$	—	$	10,756,000	$	10,756,000
Common stock warrants		—		1,613,560		—		1,613,560

Total	$	—	$	1,613,560	$	10,756,000	$	12,369,560

Warrant Liability

Schedule Of Assumption used to Calculate Fair Value

The fair value was calculated using the following assumptions:


	July 2015 Warrants						November 2015 Warrants						January 2016 Warrants
	March 31, 2016			December 31, 2015			March 31, 2016			December 31, 2015			March 31, 2016			January 11, 2016
Risk-free interest rates		0.87	%		1.31	%		1.21	%		1.76	%		1.21	%		1.58	%
Expected life		33 months			36 months			55 months			58 months			57 months			60 months
Expected dividends		0	%		0	%		0	%		0	%		0	%		0	%
Expected volatility		91.15	%		97.94	%		91.42	%		86.27	%		90.04	%		85.90	%

Senior Amortizing Convertible Notes

Schedule Of Assumption used to Calculate Fair Value

The fair values were calculated using a Binomial Lattice model and the following assumptions:


	November 2015 Notes						January 2016 Notes
	March 31, 2016			December 31, 2015			March 31, 2016			January 11, 2016
Risk-free interest rates		0.68	%		1.11	%		0.68	%		1.01	%
Expected life		1.61 years			1.86 years			1.61 years			1.83 years
Expected dividends		0	%		0	%		0	%		0	%
Expected volatility		65.0	%		57.5	%		65.0	%		60.0	%
Fair value per share of common stock	$	0.97		$	1.95		$	0.97		$	1.33

Inventory (Tables)

3 Months Ended

Mar. 31, 2016

Current Inventory

Current inventory consists of the following as of:


	March 31, 2016		December 31, 2015
Raw materials	$	527,471	$	576,898
Work-in-process		1,296,525		1,066,345
Finished goods		44,210		43,081

Inventory	$	1,868,206	$	1,686,324

Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2016

Future Minimum Payments under Lease

At March 31, 2016, future minimum payments under the lease are as follows:


Year ending December 31:
Remaining nine months in 2016	$	172,457
2017		237,749
2018		183,103

	$	593,309

Senior Amortizing Convertible Notes (Tables)

3 Months Ended

Mar. 31, 2016

Summary of Installment Amounts and Additional Conversions

The following table summarizes the installment amounts and additional conversions by the holders of the Notes issued at the First Closing through March 31, 2016:


	Principal		Interest		Total		Common Shares
Installment amount at December 31, 2015	$	65,217	$	23,651	$	88,868		56,967
Holder conversions during the quarter ended December 31, 2015		18,261		2,375		20,636		13,228

Balance December 31, 2015		83,478		26,026		109,504		70,195
Installment amount at February 29, 2016		65,217		23,681		88,898		91,953
Installment amount at March 31, 2016		65,217		14,827		80,044		88,960
Holder conversions during the quarter ended March 31, 2016		104,784		12,762		117,546		106,684

Balance, March 31, 2016	$	318,696	$	77,296	$	395,992		357,792

The following table summarizes the installment amounts and additional conversions by the holders of the Notes issued at the Second Closing through March 31, 2016:


	Principal		Interest		Total		Common Shares
Installment amount at March 2, 2016	$	404,762	$	149,300	$	554,062		*
Holder conversions during the quarter ended March 31, 2016		987,000		124,050		1,111,050		1,048,167

Balance, March 31, 2016	$	1,391,762	$	273,350	$	1,665,112		1,048,167

*	Cash payments

Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2016

Summary of Operating Expenses and Employee and Nonemployees


	Three months ended March 31,
	2016		2015
Selling, general and administrative	$	839,777	$	1,036,446
Research and development		252,711		335,630

Total	$	1,092,488	$	1,372,076


	Three months ended March 31,
	2016		2015
Employees	$	1,090,192	$	1,387,924
Nonemployees		2,296		(15,848	)

Total	$	1,092,488	$	1,372,076

Stock Option Valuation Assumptions


	Employees
	Three months ended March 31,
	2016	2015
Risk-free interest rates	1.16%-1.64%	1.65%-1.80%
Expected life	5.00-6.25 years	6.25 years
Expected dividends	0%	0%
Expected volatility	88.43%-92.24%	110.32%-111.77%


	Nonemployees
	Three months ended March 31,
	2016	2015
Risk-free interest rates	1.11%	0.03%-1.77%
Expected life	4.39 years	0.25-8.51 years
Expected dividends	0%	0%
Expected volatility	92.41%	37.36%-131.49%

Summary of Stock Option Activity

Option activity under the Plan for the three months ended March 31, 2016 was as follows:


				Outstanding Options
	Shares Available For Grant			Number of Shares			Weighted- Average Exercise Price
Balance, December 31, 2015		296,579			1,018,752		$	32.83
Shares reserved		—			—			—
Options granted		(53,333	)		53,333			1.07
Options exercised		—			—			—
Options cancelled		14,893			(14,893	)		5.10

Balance, March 31, 2016		258,139			1,057,192		$	31.62

Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2016 USD ($) shares	Jan. 06, 2016 shares	Dec. 31, 2015 shares
Schedule Of Significant Accounting Policies [Line Items]
Common stock, reverse split ratio		0.0667
Common stock authorized for issuance \| shares	150,000,000	150,000,000	13,333,333
Cash equivalents maturity period	90 days
Excise tax rate on medical devices	2.30%
Provision for returns \| $	$ 0
Minimum
Schedule Of Significant Accounting Policies [Line Items]
Short term investment maturity period	3 months
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Short term investment maturity period	1 year
Furniture and Fixtures \| Minimum
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives	5 years
Furniture and Fixtures \| Maximum
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives	7 years
Computer hardware and software \| Minimum
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives	3 years
Computer hardware and software \| Maximum
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives	5 years

Computation of Basic and Diluted Net Loss Per Share (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Numerator:
Net loss	$ (7,408,762)	$ (7,174,023)
Denominator for basic and diluted net loss per share:
Weighted-average common shares outstanding	7,840,992	4,849,061
Net loss per share-basic and diluted	$ (0.94)	$ (1.48)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Potential Shares of Common Stock Not Included in Calculation of Diluted Net Loss per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Stock Option Outstanding
Anti-dilutive Securities
Anti-dilutive as of end of each period	1,953,859	948,675
Warrants to purchase common stock
Anti-dilutive Securities
Anti-dilutive as of end of each period	4,476,839	1,613,133

Liquidity and Management's Plans - Additional Information (Detail) - USD ($)	Dec. 31, 2016	May 02, 2016	Mar. 31, 2016	Jan. 11, 2016	Dec. 31, 2015	Nov. 09, 2015	Nov. 04, 2015	Mar. 31, 2015	Dec. 31, 2014
Liquidity and Managements Plans [Line Items]
Cash and cash equivalents			$ 11,153,525		$ 7,927,240			$ 11,432,234	$ 11,619,167
Senior Amortizing Convertible Note
Liquidity and Managements Plans [Line Items]
Senior amortizing convertible notes issued							$ 25,000,000
Senior Amortizing Convertible Note \| First closing
Liquidity and Managements Plans [Line Items]
Senior amortizing convertible notes issued						$ 1,500,000
Senior Amortizing Convertible Note \| Second closing
Liquidity and Managements Plans [Line Items]
Senior amortizing convertible notes issued				$ 11,000,000
Senior Amortizing Convertible Note \| Subsequent Event \| Amendment
Liquidity and Managements Plans [Line Items]
Senior amortizing convertible notes issued		$ 12,500,000
Senior Amortizing Convertible Note \| Subsequent Event \| First closing \| Amendment
Liquidity and Managements Plans [Line Items]
Senior amortizing convertible notes issued		$ 6,250,000
Senior Amortizing Convertible Note \| Scenario, Forecast \| Second closing \| Amendment
Liquidity and Managements Plans [Line Items]
Senior amortizing convertible notes issued	$ 6,250,000

Short - term Investment and Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Jan. 11, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior amortizing convertible notes principal and interest converted into shares of common stock	$ 1,507,042
(losses) resulting from conversion of senior amortizing convertible notes	(499,568)
Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrants	1,613,560
Warrants Issued July 8, 2015 \| Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrants	1,198,689		$ 2,759,583
Warrants Issued November 9, 2015 \| Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrants	75,670		$ 118,234
Warrants Issued January 11, 2016 \| Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrants	$ 339,201	$ 515,157

Series A Warrants Fair Value Calculated Using Black-Scholes Valuation Model (Detail)		3 Months Ended	12 Months Ended
	Jan. 11, 2016	Mar. 31, 2016	Dec. 31, 2015
Warrants Issued July 8, 2015
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rates		0.87%	1.31%
Expected life		33 months	36 months
Expected dividends		0.00%	0.00%
Expected volatility		91.15%	97.94%
Warrants Issued November 9, 2015
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rates		1.21%	1.76%
Expected life		55 months	58 months
Expected dividends		0.00%	0.00%
Expected volatility		91.42%	86.27%
Warrants Issued January 11, 2016
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rates	1.58%	1.21%
Expected life	60 months	57 months
Expected dividends	0.00%	0.00%
Expected volatility	85.90%	90.04%

Summary of Fair Value Measurements of Senior Amortizing Convertible Notes and Common Stock Warrants (Detail)	Mar. 31, 2016 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior amortizing convertible notes	$ 10,756,000
Total	12,369,560
Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrants	1,613,560
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	1,613,560
Level 2 \| Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrants	1,613,560
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior amortizing convertible notes	10,756,000
Total	$ 10,756,000

Inventory - Additional Information (Detail) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Inventory [Line Items]
Long-term inventory	$ 606,000	$ 519,000

Current Inventory (Detail) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Inventory [Line Items]
Raw materials	$ 527,471	$ 576,898
Work-in-process	1,296,525	1,066,345
Finished goods	44,210	43,081
Inventory	$ 1,868,206	$ 1,686,324

Commitments and Contingencies - Additional Information (Detail) - USD ($)		3 Months Ended
	Aug. 25, 2015	Mar. 31, 2016	Mar. 31, 2015
Loss Contingencies [Line Items]
Operating lease agreement expiration date	Sep. 30, 2018	Sep. 30, 2015
Operating lease agreement term	3 years
Total rent expense		$ 58,905	$ 67,718
Number of months that require patients to be followed out in clinical trials		60 months
Minimum
Loss Contingencies [Line Items]
Operating lease, monthly base rent	$ 18,925
Maximum
Loss Contingencies [Line Items]
Operating lease, monthly base rent	$ 20,345

Future Minimum Lease Payment (Detail)	Mar. 31, 2016 USD ($)
Leases Future Minimum Payments [Line Items]
Remaining nine months in 2016	$ 172,457
2017	237,749
2018	183,103
Operating Leases, Future Minimum Payments Due, Total	$ 593,309

Notes Payable - Additional Information (Detail)				3 Months Ended
Notes Payable - Additional Information (Detail)	May 09, 2013 USD ($)	Apr. 23, 2012 USD ($) Installment	Apr. 16, 2012 USD ($) $ / shares shares	Mar. 31, 2016 USD ($)	Jan. 29, 2016 $ / shares	Jan. 11, 2016 $ / shares	Nov. 09, 2015 shares
Debt Instrument [Line Items]
Amount used to repay outstanding debt		$ 4,700,000
Repayment of principal amount				$ 333,333
Loan agreement with fixed annual rate		8.00%
Conditional amount to be placed in restricted account at SVB	$ 7,500,000
Issued warrant \| shares							1,958,728
Exercise price \| $ / shares					$ 1.09	$ 4.65
Silicon Valley Bank
Debt Instrument [Line Items]
Term loans, agreed sum			$ 20,000,000
Principal amount of loan		$ 10,000,000	$ 10,000,000
Number of installments of repayment of debt \| Installment		30
Issued warrant \| shares			7,116
Time for exercising warrant			10 years
Exercise price \| $ / shares			$ 35.10
First Amendment \| Silicon Valley Bank
Debt Instrument [Line Items]
Success fee percentage in the event the Company receives FDA approval for the Maestro Rechargeable System	187,000
Final payment fee percentage				5.00%
Final payment fee				$ 500,000
First Amendment \| Silicon Valley Bank \| November 15, 2013
Debt Instrument [Line Items]
Cumulative aggregate proceeds from new capital transactions	5,000,000
First Amendment \| Silicon Valley Bank \| April 15, 2014
Debt Instrument [Line Items]
Cumulative aggregate proceeds from new capital transactions	$ 10,000,000
First Amendment \| Silicon Valley Bank \| Until it received FDA approval for the Maestro Rechargeable System
Debt Instrument [Line Items]
Liquidity ratio (unrestricted cash divided by outstanding debt)	125.00%
First Amendment \| Silicon Valley Bank \| After FDA approval for the Maestro Rechargeable System
Debt Instrument [Line Items]
Liquidity ratio (unrestricted cash divided by outstanding debt)	75.00%

Senior Amortizing Convertible Notes - Additional Information (Detail) - USD ($)					1 Months Ended
	May 02, 2016	Jan. 11, 2016	Nov. 09, 2015	Nov. 04, 2015	Mar. 31, 2016	Jan. 29, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Convertible notes, per share price			$ 4.35	$ 4.35		$ 1.09
Exercise price		$ 4.65				$ 1.09
Convertible notes, interest rate			7.00%
Convertible notes, maturity period			24 months
Issued warrant			1,958,728
Warrants issued, exercisable time period			60 months
Subsequent Event
Debt Instrument [Line Items]
Exercise price	$ 4.65
First closing
Debt Instrument [Line Items]
Fair value of outstanding Notes					$ 1,200,000		$ 1,300,000
Second closing
Debt Instrument [Line Items]
Fair value of outstanding Notes		$ 9,900,000			9,500,000
Minimum
Debt Instrument [Line Items]
Common stock ownership percentage required to exercise warrants			4.99%
Period available for the percentage to be effective			61 days
Maximum
Debt Instrument [Line Items]
Common stock ownership percentage required to exercise warrants			9.99%
Senior Amortizing Convertible Note
Debt Instrument [Line Items]
Senior amortizing convertible notes to be issue				$ 25,000,000
Exercise price				$ 4.65
Proceeds from issuance of debt instrument including warrants				$ 12,500,000
Convertible notes, interest rate				7.00%
Senior convertible notes, maturity year				2017
Senior Amortizing Convertible Note \| Subsequent Event \| Amendment
Debt Instrument [Line Items]
Senior amortizing convertible notes to be issue	$ 12,500,000
Senior Amortizing Convertible Note \| First closing
Debt Instrument [Line Items]
Senior amortizing convertible notes to be issue			$ 1,500,000
Issued warrant			117,520
Fair value of warrants			$ 169,000
Expected dividends			0.00%
Expected volatility			84.85%
Risk-free interest rates			1.75%
Expected life			5 years
Senior Amortizing Convertible Note \| First closing \| Subsequent Event \| Amendment
Debt Instrument [Line Items]
Senior amortizing convertible notes to be issue	6,250,000
Senior Amortizing Convertible Note \| Second closing
Debt Instrument [Line Items]
Senior amortizing convertible notes to be issue		$ 11,000,000
Issued warrant		861,842
Fair value of warrants		$ 515,000
Expected dividends		0.00%
Expected volatility		85.90%
Risk-free interest rates		1.58%
Expected life		5 years
Senior Amortizing Convertible Note \| Third closing \| Subsequent Event
Debt Instrument [Line Items]
Senior amortizing convertible notes to be issue	$ 6,250,000
Issued warrant	489,684
Senior Amortizing Convertible Note \| Third closing \| Subsequent Event \| Amendment
Debt Instrument [Line Items]
Proceeds from issuance of debt instrument including warrants	$ 6,250,000
Senior Amortizing Convertible Note \| Fourth closing
Debt Instrument [Line Items]
Senior amortizing convertible notes to be issue					6,250,000
Proceeds from issuance of debt instrument including warrants					$ 6,250,000
Issued warrant					489,682

Schedule of Fair Value Assumption Calculated Using Binomial Lattice Model (Detail) - $ / shares		3 Months Ended	12 Months Ended
	Jan. 11, 2016	Mar. 31, 2016	Dec. 31, 2015
November Twenty Fifteen Notes
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rates		0.68%	1.11%
Expected life		1 year 7 months 10 days	1 year 10 months 10 days
Expected dividends		0.00%	0.00%
Expected volatility		65.00%	57.50%
Fair value per share of common stock		$ 0.97	$ 1.95
January Twenty Sixteen Notes
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rates	1.01%	0.68%
Expected life	1 year 9 months 29 days	1 year 7 months 10 days
Expected dividends	0.00%	0.00%
Expected volatility	60.00%	65.00%
Fair value per share of common stock	$ 1.33	$ 0.97

Summary of Installment Amounts and Additional Conversions (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Total	$ 1,397,538
First closing
Short-term Debt [Line Items]
Principal	318,696	$ 83,478
Interest	77,296	26,026
Total	$ 395,992	$ 109,504
Common Shares	357,792	70,195
Second closing
Short-term Debt [Line Items]
Principal	$ 1,391,762
Interest	273,350
Total	$ 1,665,112
Common Shares	1,048,167
Installment amount \| First closing
Short-term Debt [Line Items]
Principal		$ 65,217
Interest		23,651
Total		$ 88,868
Common Shares		56,967
Installment amount \| Second closing
Short-term Debt [Line Items]
Principal	$ 404,762
Interest	149,300
Total	554,062
Installment Payments February 29, 2016 \| First closing
Short-term Debt [Line Items]
Principal	65,217
Interest	23,681
Total	$ 88,898
Common Shares	91,953
Installment Payments March 31, 2016 \| First closing
Short-term Debt [Line Items]
Principal	$ 65,217
Interest	14,827
Total	$ 80,044
Common Shares	88,960
Holder Conversions \| First closing
Short-term Debt [Line Items]
Principal	$ 104,784	$ 18,261
Interest	12,762	2,375
Total	$ 117,546	$ 20,636
Common Shares	106,684	13,228
Holder Conversions \| Second closing
Short-term Debt [Line Items]
Principal	$ 987,000
Interest	124,050
Total	$ 1,111,050
Common Shares	1,048,167

Stock-Based Compensation Expense for Stock-Based Awards (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	$ 1,092,488	$ 1,372,076
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	839,777	1,036,446
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	252,711	335,630
Employees
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	1,090,192	1,387,924
Nonemployees
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	$ 2,296	$ (15,848)

Stock Options - Additional Information (Detail) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($) $ / shares shares
Schedule Of Stock Options [Line Items]
Total unrecognized compensation costs related to non-vested stock options \| $	$ 5.1
Total unrecognized compensation costs related to non-vested stock options, weighted-average period of recognition	2 years 6 months 26 days
President and Chief Executive Officer
Schedule Of Stock Options [Line Items]
Award granted, shares \| shares	516,666
Award granted, exercise price per share \| $ / shares	$ 3.75
Award granted, vesting installment percentage	2.0833%
Award vesting period	36 months
Senior Vice President of Operations and Business Development Mr. Delange
Schedule Of Stock Options [Line Items]
Award granted, shares \| shares	166,667
Award granted, exercise price per share \| $ / shares	$ 1.38
Senior Vice President of Sales
Schedule Of Stock Options [Line Items]
Award granted, shares \| shares	106,667
Award granted, exercise price per share \| $ / shares	$ 1.31
Senior Vice President of Marketing and Reimbursement
Schedule Of Stock Options [Line Items]
Award granted, shares \| shares	106,667
Award granted, exercise price per share \| $ / shares	$ 1.32
Vest as of one year from the date of his employment agreement \| President and Chief Executive Officer
Schedule Of Stock Options [Line Items]
Award granted, vesting percentage	25.00%
Vest in equal 2.0833% installments each month thereafter over the following 36 months \| President and Chief Executive Officer
Schedule Of Stock Options [Line Items]
Award granted, vesting percentage	75.00%

Estimated Grant-Date Fair Values of Employee Stock Options (Detail)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, minimum	1.16%	1.65%
Risk-free interest rate, maximum	1.64%	1.80%
Expected life		6 years 3 months
Expected dividends	0.00%	0.00%
Expected volatility factor, minimum	88.43%	110.32%
Expected volatility factor, maximum	92.24%	111.77%
Employees \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	5 years
Employees \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	6 years 3 months
Nonemployees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, minimum	1.11%	0.03%
Risk-free interest rate, maximum		1.77%
Expected life	4 years 4 months 21 days
Expected dividends	0.00%	0.00%
Expected volatility factor, minimum	92.41%	37.36%
Expected volatility factor, maximum		131.49%
Nonemployees \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life		3 months
Nonemployees \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life		8 years 6 months 4 days

Summary of Stock Option Activity (Detail) - Stock Incentive Plan 2003	3 Months Ended
	Mar. 31, 2016 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available For Grant, Beginning Balance	296,579
Shares Available For Grant, Shares reserved	0
Shares Available For Grant, Options granted	(53,333)
Shares Available For Grant, Options exercised	0
Shares Available For Grant, Options cancelled	14,893
Shares Available For Grant, Ending Balance	258,139
Outstanding Options, Number of Shares, Beginning Balance	1,018,752
Outstanding Options, Number of Shares, Shares reserved	0
Outstanding Options, Number of Shares, Options granted	53,333
Outstanding Options, Number of Shares, Options exercised	0
Outstanding Options, Number of Shares, Options cancelled	(14,893)
Outstanding Options, Number of Shares, Ending Balance	1,057,192
Outstanding Options, Weighted-Average Exercise Price, Beginning Balance \| $ / shares	$ 32.83
Outstanding Options, Weighted-Average Exercise Price, Shares reserved \| $ / shares	0
Outstanding Options, Weighted-Average Exercise Price, Options granted \| $ / shares	1.07
Outstanding Options, Weighted-Average Exercise Price, Options exercised \| $ / shares	0
Outstanding Options, Weighted-Average Exercise Price, Options cancelled \| $ / shares	5.10
Outstanding Options, Weighted-Average Exercise Price, Ending Balance \| $ / shares	$ 31.62

Stock Sales - Additional Information (Detail) - USD ($)			3 Months Ended
Stock Sales - Additional Information (Detail) - USD ($)	Jul. 08, 2015	Jun. 13, 2014	Mar. 31, 2016	Mar. 30, 2016	Jan. 29, 2016	Jan. 11, 2016	Dec. 31, 2015	Nov. 09, 2015
Class of Stock [Line Items]
Public offering selling units	2,133,333
Shares issued, price per unit	$ 7.50
Gross proceeds before deducting estimate offering expenses	$ 16,000,000
Offering costs	$ 1,400,000
Exercise price					$ 1.09	$ 4.65
Beneficial ownership percentage	9.99%
Series A Warrants
Class of Stock [Line Items]
Exercise price	$ 9.00			$ 0.88	$ 0.97		$ 1.50	$ 2.40
Warrants exercisable period	42 months
Warrants to purchase common stock
Class of Stock [Line Items]
Offering costs	$ 532,000
Series C Warrants
Class of Stock [Line Items]
Exercise price	$ 7.50
Warrant issued	0
Cowen and Company LLC
Class of Stock [Line Items]
Gross proceeds before deducting estimate offering expenses			$ 7,600,000
Commission or discount percentage on issue of shares		3.00%
Number of shares sold			367,903
Minimum
Class of Stock [Line Items]
Beneficial ownership percentage	4.99%
Maximum \| Cowen and Company LLC
Class of Stock [Line Items]
Gross proceeds before deducting estimate offering expenses		$ 25,000,000
Weighted Average \| Cowen and Company LLC
Class of Stock [Line Items]
Sale of stock, price per share			$ 20.60