Note 12 - Summary of Stock Options - Summary of Option Activity Under All Plans (Details) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares
Options outstanding (in shares) | shares	3,173,103
Options outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 7.51
Options outstanding, weighted average remaining contractual term (Year)	8 years 9 months 18 days	9 years
Options outstanding, aggregate intrinsic value | $	$ 0	$ 0
Options granted (in shares) | shares	955,000
Options granted, weighted average exercise price (in dollars per share) | $ / shares	$ 1.25
Options exercised (in shares) | shares	0
Options exercised, weighted average exercise price (in dollars per share) | $ / shares
Options canceled (in shares) | shares	(4,094)
Options canceled, weighted average exercise price (in dollars per share) | $ / shares	$ 7.69
Options outstanding (in shares) | shares	4,124,009	3,173,103
Options outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 6.06	$ 7.51
Vested and exercisable and expected to vest (in shares) | shares	3,873,550
Vested and exercisable and expected to vest, end of period, weighted average exercise price (in dollars per share) | $ / shares	$ 6.29
Vested and exercisable and expected to vest, end of period, weighted average remaining contractual term (Year)	8 years 9 months 18 days
Vested and exercisable and expected to vest, end of period, aggregate intrinsic value | $	$ 0
Vested and exercisable (in shares) | shares	1,266,335
Vested and exercisable, end of period, weighted average exercise price (in dollars per share) | $ / shares	$ 13.10
Vested and exercisable, end of period, weighted average remaining contractual term (Year)	8 years 3 months 18 days
Vested and exercisable, end of period, aggregate intrinsic value | $	$ 0