Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

	Common Stock Issued	Proceeds
Series A Warrants	251	$	1,054
Series K Warrants	300,660		1,262,712
	300,911	$	1,263,766

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

	Year Ended December 31,
	201 9	201 8
Warrants to purchase common stock - liability classified	54,989	55,963
Warrants to purchase common stock - equity classified	—	6
Convertible 2020 Notes	974,139	1,071,674
Outstanding options to purchase common stock	1,561	2,311
Stock appreciation rights	127,225	132,566
Unvested restricted common stock	—	290,300
Total	1,157,914	1,552,820