Note 12 - Net Loss Per Share Attributable to Common Stockholders (Tables)

6 Months Ended

Jun. 30, 2019

Notes Tables

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

	Three Months Ended June 30,						Six Months Ended June 30,
	2019			2018			2019			2018
Net loss	$	(5,637	)	$	(8,871	)	$	(6,976	)	$	(6,557	)
Series B and C preferred dividend		—			—			—			(339	)
Net loss attributable to common stockholders – diluted calculation	$	(5,637	)	$	(8,871	)	$	(6,976	)	$	(6,896	)
Shares used to compute net loss per share – basic and diluted		14,597,446			7,141,189			10,969,473			5,477,265
Net loss per share – basic and diluted	$	(0.39	)	$	(1.24	)	$	(0.64	)	$	(1.26	)

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Options to purchase common stock		1,561,067		878,555		1,212,654		765,702
Warrants to purchase common stock		11,802,695		10,794		5,944,948		8,230
Warrant to purchase convertible preferred stock		—		—		—		1,797
Series B and C convertible preferred stock outstanding, including cumulative dividends		—		—		—		431,064
Series A convertible preferred stock outstanding		—		—		—		24,723
Convertible promissory notes, related party (as converted)		—		—		—		373,388
Total potentially dilutive securities excluded from denominator of the diluted earnings per share computation		13,363,762		889,349		7,157,602		1,604,904