When would you recommend surgery for dequervains tenosynovitis?

Failed non operative: When nsaids, ice, rest, activity modification, wrist bracing, & cortisone injection have not helped and you've tried these things for 3-6 months at least.

Failed non-op tx: Non-operative treatment for dequervain's tendinitis includes forearm based thumb spica splinting, anti-inflammatory medication, corticosteroid injection, rest and activity modification. Failure to respond to these non-operative modalities would be an indication for surgical release with local extensor tenosynovectomy.

Sometimes: In certain cases surgery may be required. Try conservative measures first: nsaids, bracing, activity modification, and a limited number (my limit is 2) of cortisone injections.