Note 10 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]

	Year Ended December 31,
	2019			2018
Domestic	$	(14,965	)	$	(17,855	)
Foreign		(27	)		(2,874	)
Total	$	(14,992	)	$	(20,729	)

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

	Year Ended December 31,
	2019			2018
Income tax benefit computed at federal statutory tax rate	$	(3,148	)	$	(4,348	)
Permanent differences		1			6
Write-off of deferred tax asset		2,048			-
Stock compensation - permanent items		-			325
State income taxes, net of federal benefit		(930	)		(958	)
Tax credits		(465	)		(1,466	)
Change in valuation allowance		2,449			5,409
Foreign rate differential		5			602
Other		40			430
Total	$	-		$	-

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

	Year Ended December 31,
	2019			2018
Deferred tax assets:
Net operating loss carryforwards	$	11,090		$	6,742
Federal and state tax credits		3,587			3,122
Accrued expenses		-			411
Patents		74			132
Stock-based compensation		-			1,782
Other		59			169
Total deferred tax assets		14,810			12,358
Valuation allowance		(14,810	)		(12,358	)
Net deferred assets	$	-		$	-