Figure. Photograph of thenar atrophy seen on the right hand compared with the left hand.
A 60-year-old woman presents with right wrist and hand pain that has been present for more than a year. In the past 6 months, the pain at night has worsened and she noticed muscle atrophy in her right palm. The pain starts at the palm and can radiate to the thumb, index, and ring fingers. She sporadically has used a night splint but it does not seem to help. On physical examination, the patient has obvious thenar atrophy compared with the left hand (Figure) and weakness with thumb abduction.
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Thenar eminence atrophy is a classic physical finding of chronic carpal tunnel syndrome. Thenar atrophy is a sign of severe and prolonged medial nerve compression and itself is an indication for surgical carpel tunnel release. Although the most common cause of thenar atrophy is carpel tunnel syndrome, C8/T1 radiculopathy and median neuropathy (in the arm) can also be a cause.1,2
Carpal tunnel syndrome is diagnosed by multiple factors including clinical picture, physical examination findings (carpal compression test, positive Tinel, prayer, and Phalen signs), and electrodiagnostic testing.2 Patients with thenar atrophy who undergo carpal tunnel release can expect significant improvement in hand strength up to 6 months postoperatively along with improvement in thenar atrophy. Fernandes et al found 21% improvement in grip strength and 30% increase in tip-pinch strength 6 months after carpal tunnel release in patients with thenar atrophy.1
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
1. Fernandes CH, Meirelles LM, Raduan Neto J, Nakachima LR, Dos Santos JB, Faloppa F. Carpal tunnel syndrome with thenar atrophy: evaluation of the pinch and grip strength in patients undergoing surgical treatment. Hand (N Y). 2013;8(1):60-63. doi:10.1007/s11552-012-9471-8
2. Hoppe B, LeVan D. Hand atrophy. JBJS JOPA. 2021;9(1):e20.00022. doi:10.2106/JBJS.JOPA.20.00022