Note 9 - Stockholders' Equity (Deficit) (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Common Stock Reserved for Future Issuance [Table Text Block]

Stock options outstanding	1,032,211
Shares available for grant under equity incentive plan	732,149
Estimated common shares issuable upon conversion of notes payable and accrued interest	383,947
Common shares issuable under outstanding commons stock purchase warrants	2,035,197
	4,183,504