Note 6 - Stockholders' Equity and Stock-based Compensation - Summary of Performance Option Activity (Details) - Performance Options [Member] - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Options balances, number of shares (in shares)	520,302
Options balances, weighted average exercise price (in dollars per share)	$ 10.08
Options balances, weighted average remaining life (Year)	8 years 10 months 24 days	7 years 7 days
Options granted, number of shares (in shares)	782,300
Options granted, weighted average exercise price (in dollars per share)	$ 2.92
Options exercised, number of shares (in shares)	0
Options exercised, weighted average exercise price (in dollars per share)	$ 0
Options canceled, number of shares (in shares)	0
Options canceled, weighted average exercise price (in dollars per share)	$ 0
Options expired, number of shares (in shares)	(78,172)
Options expired, weighted average exercise price (in dollars per share)	$ 12.84
Options balances, number of shares (in shares)	1,224,430	520,302
Options balances, weighted average exercise price (in dollars per share)	$ 5.33	$ 10.08
Options exercisable, number of shares (in shares)	208,189
Options exercisable, weighted average exercise price (in dollars per share)	$ 10.72
Options exercisable, weighted average remaining life (Year)	6 years 8 months 15 days