Note 3 - Balance Sheet Details - Summary of Accrued Liabilities (Details) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Disclosure Text Block [Abstract]
Accrued accounts payable	$ 780,000	$ 195,000
Accrued clinical trial costs	132,000	158,000
Accrued director stipends	111,000	110,000
Accrued other	11,000	0
Accrued Liabilities, Current, Total	$ 1,034,000	$ 463,000