Note 16 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Years ended December 31 ,
	201 7			201 6			201 5
Tax at federal statutory rat e	$	(4,185	)	$	(3,505	)	$	(2,277	)
State, net of federal benefi t		(1,238	)		(315	)		(335	)
Research and development credi t		(135	)		(89	)		(51	)
Stock-based compensatio n		344			136			89
Nondeductible interes t		—			590			471
Warrant and derivative revaluatio n		—			328			(589	)
Change in Federal tax rat e		8,172			—			—
Othe r		7			94			5
Change in valuation allowanc e		(2,965	)		2,761			2,687
Total provision for income taxe s	$	—		$	—		$	—

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	December 31 ,
	201 7			201 6
Accrued compensatio n	$	110		$	154
Inventory adjustment s		449			708
Depreciation and amortization - noncurren t		146			252
Share-based compensatio n		558			273
Net operating loss and tax credit carryforwards - noncurren t		17,368			20,196
Othe r		34			47
Gross deferred tax asse t		18,665			21,630
Valuation allowanc e		(18,665	)		(21,630	)
Net deferred tax asse t	$	—		$	—

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

	December 31 ,
	201 7		201 6
Balance, beginning of yea r	$	608	$	531
Additions based on tax positions related to the current yea r		117		77
Additions (reductions) for tax positions related to prior year s		—		—
Balance, end of yea r	$	725	$	608