Note 12 - Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Years ended December 31,
	2019			2018			2017
Numerator:
Net loss	$	(14,709	)	$	(13,987	)	$	(12,308	)
Denominator:
Weighted average shares used to compute net loss per share, basic and diluted		5,644,328			4,264,178			4,240,060
Net loss per share, basic and diluted	$	(2.61	)	$	(3.28	)	$	(2.90	)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	Years ended December 31,
	2019		2018		2017
Stock options to purchase common stock		821,464		608,547		468,122
Unvested restricted stock units		36,981		29,698		10,888
Common stock warrants		2,435,808		296,296		-
Total		3,294,253		934,541		479,010