Note 10 - Net Loss Per Share - Schedule of Antidilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Number of potential common shares excluded (in shares)	4,317,405	375,199
Employee Stock Option [Member]
Number of potential common shares excluded (in shares)	487,941	117,301
Series A Convertible Preferred Stock [Member]
Number of potential common shares excluded (in shares)		55,835
Series B Convertible Preferred Stock [Member]
Number of potential common shares excluded (in shares)	774,983
Warrant [Member]
Number of potential common shares excluded (in shares)	3,054,481	202,063