Note 13 - Summary of Stock Options - Summary of Option Activity Under All Plans (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Options outstanding (in shares)	3,173,103	986,399
Options outstanding, weighted average exercise price (in dollars per share)	$ 7.51	$ 19.10
Options outstanding, weighted average remaining contractual term (Year)		9 years	8 years 10 months 24 days
Options outstanding, aggregate intrinsic value		$ 0	$ 675,000
Options granted (in shares)		2,251,000
Options granted, weighted average exercise price (in dollars per share)		$ 2.73
Options exercised (in shares)		0
Options exercised, weighted average exercise price (in dollars per share)
Options canceled (in shares)		(64,296)
Options canceled, weighted average exercise price (in dollars per share)		$ 17.85
Vested and exercisable and expected to vest (in shares)		2,947,472
Vested and exercisable and expected to vest, end of period, weighted average exercise price (in dollars per share)		$ 7.83
Vested and exercisable and expected to vest, end of period, weighted average remaining contractual term (Year)		9 years
Vested and exercisable and expected to vest, end of period, aggregate intrinsic value		$ 0
Vested and exercisable (in shares)		774,800
Vested and exercisable, end of period, weighted average exercise price (in dollars per share)		$ 18.81
Vested and exercisable, end of period, weighted average remaining contractual term (Year)		8 years 6 months
Vested and exercisable, end of period, aggregate intrinsic value		$ 0