Note 8 - Controlled Launch (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Feb. 28, 2021
Number of KOLs				70
Controlled Launch, Program Expenses	$ 100	$ 1,800
Revenue from Contract with Customer, Excluding Assessed Tax	700	1,418	$ 0
Redemption of Non Cash Credits [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 400	$ 1,100
Minimum [Member]
Number of Patients Participating in Procedure				40
Maximum [Member]
Number of Patients Participating in Procedure				50