Note 12 - Income Taxes and Tax Status (Tables)

12 Months Ended

Dec. 31, 2022

Notes Tables

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	2022			2021
Tax benefit at statutory rate	$	(2,061	)	$	(2,589	)
State tax benefit		(422	)		(530	)
Increase in valuation allowance		2,416			3,368
Other		67			(249	)
	$	-		$	-

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	2022			2021
Gross deferred tax assets:
Net operating loss carry-forward	$	75,470		$	78,600
Research and development credit carry-forward		5,356			6,028
Stock compensation		1,127			356
Patents and other		1,482			1,470
Contingent payment obligations		7,033			6,341
Fixed assets		(2	)		53
Lease liabilities		1			38
		90,467			92,886
Less valuation allowance		(90,467	)		(92,886	)
		-			-
Gross deferred tax liabilities:
Convertible debt		-			-
		-			-
Net deferred tax asset	$	-		$	-

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

	2022			2021
Unrecognized tax benefits – beginning of year	$	653		$	927
Reduction as a result of lapse of statute of limitations		(15	)		(274	)
Unrecognized tax benefits – end of year	$	638		$	653