Note 13 - Common Stock Reserved for Issuance - Common Stock Reserved for Issuance (Details) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Outstanding stock options and RSUs (in dollars per share)	$ 7,878,714	$ 5,977,179
Shares reserved for conversion of future preferred share issuance (in shares)	1,209,245	1,209,245
Shares reserved for future option grants and RSUs (in shares)	1,230,036	589,064
Total common stock reserved for issuance (in shares)	43,474,364	40,931,857
Lincoln Park [Member]
Total common stock reserved for issuance (in shares)	5,222,867	5,222,867
Madryn Noteholders [Member]
Total common stock reserved for issuance (in shares)	8,213,880	8,213,880
Common Stock [Member]
Outstanding common stock warrants (in shares)	15,928,867	15,928,867
Preferred Stock [Member]
Preferred shares (in shares)	3,790,755	3,790,755