Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net loss	$ (6,661)	$ (15,343)	$ (2,602)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	922	1,381	1,904
Amortization of debt discounts and financing issuance costs	459	168
Restructuring reserve adjustment	(123)
Long-lived asset impairment		411
Change in carrying value of contingent liability		(668)
Loss on debt extinguishment	405
Provision for adjustments to accounts receivable and doubtful accounts	182	70	31
Provision for excess and obsolete inventory		11	48
Loss (gain) on disposal of fixed assets	(6)	27	1
Tax benefits from stock-based compensation			(5)
Non-cash compensation related to stock options and restricted stock	1,171	1,528	2,158
Deferred income taxes	(585)	(137)
Change in operating accounts:
Accounts receivable	(365)	3,368	40
Prepaid expenses and other assets	154	475	790
Accounts payable and accrued liabilities	(2,947)	(1,966)	(1,362)
Deferred revenue	(25)	(828)	(1,058)
Net cash used in operating activities	(7,419)	(11,503)	(55)
Investing activities:
Cash paid for acquisitions, net of cash acquired		(2,485)
Capital expenditures	(77)	(500)	(124)
Proceeds from the sale of short-term investments		4,079
Purchases of short-term investments			(1,199)
Net cash provided by (used in) investing activities	(77)	1,094	(1,323)
Financing activities:
Cash received from issuance of common stock and warrants, net of offering costs	2,056
Cash received from issuance of preferred stock, net of offering costs	2,413
Cash received from short-term secured promissory notes	1,800
Cash received from related-party notes payable, net of issuance costs of $97 (2016)	1,200	1,903
Cash received from notes payable, net of issuance costs of $97 (2016)		1,903
Cash received from stock sale for employee stock purchase plan	3	13	17
Cash received from exercise of stock options			10
Tax benefits received from stock-based compensation			5
Net cash provided by financing activities	7,472	3,819	32
Net decrease in cash and cash equivalents	(24)	(6,590)	(1,346)
Cash and cash equivalents, beginning of period	2,229	8,819	10,165
Cash and cash equivalents, end of period	2,205	2,229	8,819
Supplemental disclosures of cash flow information:
Cash paid for income taxes	15	27	17
Cash paid for interest expense	662	21
Change in unrealized gain (loss) on short-term investments		$ 2	$ (1)
Issuance of common stock warrants in connection with stock offering	64
Issuance of preferred stock in settlement of senior subordinated debt	$ 2,800