Note 12 - Segment Reporting - Summary of Operating Results by Reportable Segments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net revenues	$ 13,047,000	$ 9,672,000
Cost of revenues	7,351,000	7,479,000
Gross profit	5,696,000	2,193,000
Operating expenses	10,429,000	45,738,000
Operating loss	(4,733,000)	(43,545,000)
Depreciation and amortization	805,000	670,000
Stock-based compensation expense	614,000	652,000
Goodwill	781,000	781,000	$ 13,976,000
Total assets	15,214,000	14,611,000
Clinical Development [Member]
Net revenues	90,000	203,000
Clinical Development [Member] | Operating Segments [Member]
Net revenues	12,957,000	9,469,000
Cost of revenues	7,175,000	7,205,000
Gross profit	5,782,000	2,264,000
Operating expenses	7,081,000	8,398,000
Operating loss	(1,299,000)	(6,134,000)
Depreciation and amortization	530,000	398,000
Stock-based compensation expense	393,000	179,000
Goodwill	781,000	781,000
Total assets	13,420,000	10,815,000
Device [Member]
Net revenues	12,957,000	9,469,000
Device [Member] | Operating Segments [Member]
Net revenues	90,000	203,000
Cost of revenues	176,000	274,000
Gross profit	(86,000)	(71,000)
Operating expenses	3,348,000	37,340,000
Operating loss	(3,434,000)	(37,411,000)
Depreciation and amortization	275,000	272,000
Stock-based compensation expense	221,000	473,000
Goodwill
Total assets	$ 1,794,000	$ 3,796,000