Note 12 - Equity-based Compensation (Tables)

9 Months Ended

Sep. 30, 2016

Nonemployee [Member]

Notes Tables

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Nine Months Ended September 30,
Assumption	2016			2015
Expected price volatility		88	%		79	%
Expected term (in years)		9.99			9.38
Risk-free interest rate		1.61	%		2.07	%
Dividend yield		0.00	%		0.00	%
Weighted-average fair value of options granted during the period	$	2.29		$	13.50

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

(in thousands, except years and per share data)	Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (years)		Aggregate Intrinsic Value
Outstanding at December 31, 2015		388		$	32.03		6.2		19
Options granted		1,199		$	2.71
Restricted stock units granted		74		$	—
Options exercised		-		$	—
Restricted stock units vested		(74	)	$	—
Options forfeited/cancelled/expired		(85	)	$	36.87
Outstanding at September 30, 2016		1,502		$	8.64		8.9	$	1,718
Vested and expected to vest at September 30, 2016		1,478		$	8.40		8.9	$	1,691
Vested at September 30, 2016		325		$	27.04		6.2	$	—
Exercisable at September 30, 2016		325		$	27.04		6.2	$	—

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Nine months ended September 30,
Assumption	2016			2015
Expected price volatility		84	%		74	%
Expected term (in years)		7.03			5.35
Risk-free interest rate		1.56	%		1.65	%
Dividend yield		0.00	%		0.00	%
Weighted-average fair value of options granted during the period	$	2.03		$	10.00

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(in thousands)	2016		2015		2016		2015
Research and development	$	63	$	86	$	142	$	266
Sales and marketing		62		-		113		-
General and administrative		585		135		972		743
Total stock-based compensation expense	$	710	$	221	$	1,227	$	1,009