To evaluate outcomes of carpal and cubital tunnel release in patients with hereditary neuropathy with pressure palsies (HNPP) and Charcot-Marie-Tooth-1A (CMT1A).

HNPP and CMT1A genetically diagnosed between 2017 and 2020 with electrophysiologic, ultrasonographic evaluations and longitudinal follow up for CTS and CuTS surgical decompression were reviewed.

Clinical CTS occurred in 57.9%(11/19) of HNPP and 14.3%(6/42) of CMT1A while CuTS occurred in 42.1%(8/19) of HNPP and 7.1%(3/42) of CMT1A. Twelve CTS (7 HNPP and 5 CMT1A) and 5 CuTS (1 CMT1A and 4 HNPP) underwent surgical decompression with an average follow up 62 months (4-180 months). Preoperatively, median and ulnar sensory amplitudes were absent in all CMT1A but variably reduced in HNPP (median=16±8.2 μV, ulnar=15.3±5.3 μV). In HNPP, median and ulnar nerve ultrasound showed focal enlargements at the carpal tunnel [mean cross-sectional area (CSA)=14.3±3.5 mm2 at wrist, 6±1 mm2 at forearm] and the cubital tunnel (CSA=17±7 mm2). In CMT1A, diffuse median nerve enlargements occurred (mean CSA=16 mm2 at wrist, 22.5±0.5 mm2 at forearm) without focal enlargements at the carpal or cubital tunnel. Sustained postsurgical improvements at last visit determined by pain reduction and improved hand function (sensation, strength) occurred in 80% of CMT1A and 43% of HNPP. In HNPP, CTS symptom improvement was seen only in patients with activity-provoking symptoms. Only the CMT1A case improved with CuTS surgery while 50%(2/4) of HNPP patients immediately worsened clinically and electrophysiologically.

CMT1A patients are more likely than HNPP patients to see benefits from upper extremity nerve decompression. Nerve conduction abnormalities and sonographic nerve enlargements aid the diagnosis but do not inform on surgical outcomes. Recognizing activity induced symptoms in HNPP patients best informs who will benefit from decompressive surgery.