Note 8 - Segment Reporting - Summary of Operating Results by Reportable Segments (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Net revenues	$ 1,867,000	$ 3,252,000
Cost of revenues	1,515,000	1,875,000
Gross profit	352,000	1,377,000
Operating expenses	3,608,000	3,493,000
Operating loss	(3,256,000)	(2,116,000)
Depreciation and amortization	159,000	185,000
Stock-based compensation expense	137,000	247,000
Goodwill	13,976,000		$ 13,976,000
Total assets	50,181,000		$ 51,111,000
Operating loss	(3,256,000)	(2,116,000)
Clinical Development [Member]
Net revenues	62,000
Clinical Development [Member] | Operating Segments [Member]
Net revenues	62,000	153,000
Cost of revenues	71,000	124,000
Gross profit	(9,000)	29,000
Operating expenses	1,179,000	1,934,000
Operating loss	(1,188,000)	(1,905,000)
Depreciation and amortization	68,000	116,000
Stock-based compensation expense	98,000	151,000
Goodwill	13,195,000
Total assets	38,941,000
Operating loss	(1,188,000)	(1,905,000)
Device [Member]
Net revenues	1,805,000
Device [Member] | Operating Segments [Member]
Net revenues	1,805,000	3,099,000
Cost of revenues	1,444,000	1,751,000
Gross profit	361,000	1,348,000
Operating expenses	2,429,000	1,559,000
Operating loss	(2,068,000)	(211,000)
Depreciation and amortization	91,000	69,000
Stock-based compensation expense	39,000	96,000
Goodwill	781,000
Total assets	11,240,000
Operating loss	$ (2,068,000)	$ (211,000)