Secondary Carpal Tunnel Syndrome Due to Flexor Tenosynovitis in a Diabetic Patient.

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy of the upper limb. Although many cases are idiopathic, structural or inflammatory pathology of the flexor tendon sheath can result in secondary median nerve compression. Diabetes mellitus predisposes to such changes due to chronic connective tissue alterations, but secondary CTS arising solely from noninfective flexor tenosynovitis remains uncommon. A 49-year-old woman with recently diagnosed type 2 diabetes presented with a 2-month history of progressive right-wrist pain, paresthesia, and volar swelling. Magnetic resonance imaging revealed marked tenosynovitis of the finger flexors with palmar bowing of the flexor retinaculum and associated median nerve edema, whereas nerve conduction studies confirmed compressive neuropathy. Conservative therapy failed, and open carpal tunnel release was performed, yielding immediate symptom relief and improved hand function at 6-week follow-up. Secondary CTS due to chronic flexor tenosynovitis should be suspected in diabetic patients with refractory symptoms. Early multimodal evaluation and timely decompression may prevent irreversible neuropathy.