CoSense Joint Venture Agreement	12 Months Ended
Dec. 31, 2020
Equity Method Investments And Joint Ventures [Abstract]
CoSense Joint Venture Agreement	Note 9. CoSense Joint Venture Agreement In December 2017, the Company entered into a joint venture with OptAsia Healthcare Limited (OAHL), with respect to its CoSense product by agreeing to sell shares of Capnia, its then wholly-owned subsidiary, to OAHL. CoSense was based on the Company’s Sensalyze Technology Platform and received 510(k) clearances from the FDA and CE Mark certification in the E.U. The Company’s entry into the joint venture resulted from a comprehensive review of strategic alternatives for its legacy products and product candidates following its transition to a primarily therapeutic drug product company. The terms of the Joint Venture Agreement provide that OAHL would invest up to a total of $2.2 million in Capnia’s common shares on an incremental quarterly basis commencing in December 2017. OAHL was also responsible for funding a portion of the Capnia operations. The Joint Venture Agreement provided that Capnia would issue shares of common stock to OAHL based on a negotiated price of $1.00 per share when the cumulative investment made by OAHL equaled or exceeded $1.2 million. For financial reporting purposes, Capnia’s assets, liabilities and results of operations had historically been consolidated with those of the Company. During October 2018, the Company and OAHL determined and agreed that the cumulative investment made by OAHL exceeded $1.2 million during the quarter ended September 30, 2018. Accordingly, on October 16, 2018, Capnia issued 1,690,322 shares of its common stock to OAHL, representing 53% of its outstanding shares. After the share issuance the Company no longer held a controlling interest in Capnia and resulted in the deconsolidation of Capnia’s financial statements from those of the Company and a $2.0 million gain was recognized in the fourth quarter of 2018 as a result of the deconsolidation. Of this amount, $1.2 million related to the remeasurement of the Company’s retained interest in the joint venture to fair value which was measured based on the negotiated price of $1.00 per share for Soleno’s remaining ownership of 1,480,000 shares less a 23% discount for lack of control over Capnia. The total gain was included in other income from continuing operations on the Company’s consolidated statements of operations. The remaining 47% investment in Capnia was classified as an equity method investment and presented as a Minority interest investment in former subsidiary in the consolidated balance sheet. During September 2019, the Company sold its remaining 47% investment in Capnia to Sinon for a total purchase price of $0.5 million. As of the sale date, the Company had a minority interest investment in former subsidiary balance of $0.5 million, after recording $0.5 million for its share of Capnia’s losses during 2019 up until the date of sale, which is included in the line titled “Loss from minority interest investment” in the Company’s consolidated statements of operations. A gain of approximately $33,000 was recognized upon the sale and is presented, together with the Company’s share of Capnia’s net losses during the period, in the consolidated statements of operations in the line titled “Loss from minority interest investment”. Following the transaction, the Company has no interest remaining in Capnia and the previous joint venture agreement with OAHL has been terminated.

CoSense Joint Venture Agreement

12 Months Ended

Dec. 31, 2020

Equity Method Investments And Joint Ventures [Abstract]

Note 9. CoSense Joint Venture Agreement

In December 2017, the Company entered into a joint venture with OptAsia Healthcare Limited (OAHL), with respect to its CoSense product by agreeing to sell shares of Capnia, its then wholly-owned subsidiary, to OAHL. CoSense was based on the Company’s Sensalyze Technology Platform and received 510(k) clearances from the FDA and CE Mark certification in the E.U. The Company’s entry into the joint venture resulted from a comprehensive review of strategic alternatives for its legacy products and product candidates following its transition to a primarily therapeutic drug product company. The terms of the Joint Venture Agreement provide that OAHL would invest up to a total of $2.2 million in Capnia’s common shares on an incremental quarterly basis commencing in December 2017. OAHL was also responsible for funding a portion of the Capnia operations. The Joint Venture Agreement provided that Capnia would issue shares of common stock to OAHL based on a negotiated price of $1.00 per share when the cumulative investment made by OAHL equaled or exceeded $1.2 million. For financial reporting purposes, Capnia’s assets, liabilities and results of operations had historically been consolidated with those of the Company.

During October 2018, the Company and OAHL determined and agreed that the cumulative investment made by OAHL exceeded $1.2 million during the quarter ended September 30, 2018. Accordingly, on October 16, 2018, Capnia issued 1,690,322 shares of its common stock to OAHL, representing 53% of its outstanding shares. After the share issuance the Company no longer held a controlling interest in Capnia and resulted in the deconsolidation of Capnia’s financial statements from those of the Company and a $2.0 million gain was recognized in the fourth quarter of 2018 as a result of the deconsolidation. Of this amount, $1.2 million related to the remeasurement of the Company’s retained interest in the joint venture to fair value which was measured based on the negotiated price of $1.00 per share for Soleno’s remaining ownership of 1,480,000 shares less a 23% discount for lack of control over Capnia. The total gain was included in other income from continuing operations on the Company’s consolidated statements of operations. The remaining 47% investment in Capnia was classified as an equity method investment and presented as a Minority interest investment in former subsidiary in the consolidated balance sheet. During September 2019, the Company sold its remaining 47% investment in Capnia to Sinon for a total purchase price of $0.5 million. As of the sale date, the Company had a minority interest investment in former subsidiary balance of $0.5 million, after recording $0.5 million for its share of Capnia’s losses during 2019 up until the date of sale, which is included in the line titled “Loss from minority interest investment” in the Company’s consolidated statements of operations. A gain of approximately $33,000 was recognized upon the sale and is presented, together with the Company’s share of Capnia’s net losses during the period, in the consolidated statements of operations in the line titled “Loss from minority interest investment”. Following the transaction, the Company has no interest remaining in Capnia and the previous joint venture agreement with OAHL has been terminated.