Note 12 - Income Taxes - Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Tax at federal statutory rate	$ (3,657)	$ (3,991)
State taxes, net of federal benefit	(711)	(760)
Permanent differences	(445)	56
Change in valuation allowance	5,104	4,909
Research credits	(286)	(211)
Other	(5)	(3)
Provision for taxes	$ 0	$ 0

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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