Note 5 - Stockholders' Equity, Stock Options and Warrants - Summary of Transactions for Stock Options and Warrants (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Warrants, outstanding (in shares)	1,816,437	1,584,995
Warrants, average exercise price (in dollars per share)	$ 22.60	$ 33.20
Warrants, issued (in shares)	0	1,053,136
Issued, average exercise price, warrants (in dollars per share)	$ 0	$ 14.00
Warrants,forfeited (in shares)	0	0
Warrants,expired (in shares)	(4,058)	(5,422)
Expired, average exercise price, warrants (in dollars per share)	$ 200.00	$ 329.60
Warrants,cancelled (in shares)		(816,272)
Cancelled, average exercise price, warrants (in dollars per share)		$ 30.20
Warrants, outstanding (in shares)	1,812,379	1,816,437
Warrants, average exercise price, warrants (in dollars per share)	$ 22.20	$ 22.60
Share-Based Payment Arrangement, Option [Member]
Number of Shares Outstanding (in shares)	49,053	53,144
Average Exercise Price Outstanding (in dollars per share)	$ 91.69	$ 96.60
Number of Shares Issued (in shares)	488	1,599
Average Exercise Price Issued (in dollars per share)	$ 6.70	$ 8.40
Number of Shares Forfeited (in shares)	0	(2,013)
Average Exercise Price Forfeited (in dollars per share)	$ 0	$ 17.60
Number of Shares Expired (in shares)	(1,736)	(3,677)
Average Exercise Price Expired (in dollars per share)	$ 148.58	$ 208.40
Number of Shares Cancelled (in shares)		0
Average Exercise Price Cancelled (in dollars per share)		$ 0
Number of Shares Outstanding (in shares)	47,805	49,053
Average Exercise Price Outstanding (in dollars per share)	$ 84.88	$ 91.69