Note 10 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Notes Tables

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

	Year Ended
	December 31,
	2016			2015
Income tax provision (benefit) at statutory rate		(34	)%		(34	)%
State income taxes, net of federal benefit		(2	)%		(6	)%
Change in valuation allowance		33	%		39	%
Other		3	%		1	%
Effective tax rate		-	%		-	%

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

	December 31,
	2016			2015
Deferred tax assets:
Net operating loss carryforwards	$	16,888		$	10,726
Capitalized start up costs		5,944			7,225
Research and development credits		518			248
Accruals and reserves		1,095			497
Total deferred tax assets		24,445			18,696
Deferred tax liabilities:
Fixed assets and depreciation		(7	)		(8	)
Valuation allowance		(24,438	)		(18,688	)
Net deferred tax assets	$	-		$	-

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

	Year Ended
	December 31,
	2016		2015
Balance at the beginning of the year	$	128	$	97
Additions based upon tax positions related to the current year		140		31
Balance at the end of the year	$	268	$	128