Treatment of Cubital Tunnel Syndrome with First Dorsal Interosseous Muscle Weakness and Intrinsic Hand Muscle Atrophy
This protocol applies to cubital tunnel syndrome presenting with first dorsal interosseous muscle weakness or intrinsic hand muscle atrophy, alongside decreased compound muscle action potential (CMAP) amplitude of the ulnar nerve on electrodiagnostic studies — with or without abnormal electromyography.
Clinical Scenario
Severe electrodiagnostic findings — decreased ulnar nerve CMAP amplitude, with or without abnormal EMG — indicate significant axonal involvement. Clinically, this manifests as hand weakness, clawing of the fourth and fifth fingers, and atrophy of intrinsic hand muscles, often accompanied by profound sensory disturbance.
Treatment Approach
When viable motor endplates are present, management involves surgical decompression at the cubital tunnel combined with a nerve transfer technique to augment motor recovery. The complete regimen — including the specific surgical approach, nerve transfer criteria, and indications for addressing concurrent compression — is available in the full protocol.
Target Outcomes
- Resolution of clawing of the fourth and fifth fingers
- Resolution of intrinsic hand muscle wasting
- Improved compound muscle action potential amplitude of the ulnar nerve, assessed at approximately 6 to 7 months after nerve transfer
References
DOI: 10.1016/j.jhsg.2022.07.008
- Severe findings of EDX include decreased CMAP with/without abnormal electromyography findings.
- Hand weakness, clawing.
- Atrophy of intrinsic hand muscles with profound sensory disturbances.
- For severe primary or recurrent CuTS, nerve transfers have been described as a technique to "supercharge" the ulnar nerve, and thus facilitate faster and more complete recovery with minimal morbidity.
- Recently, Doherty et al found that more than three quarters of patients with advanced CuTS had partial or complete resolution of clawing or muscle wasting following end-to-side AIN to ulnar nerve motor transfer.
- For concomitant CuTS and Guyon's canal compression, treat both at index procedure.
- Improvement in function within the first 2 to 3 months is thought to be related to remyelination, 4 to 5 months for axonal regeneration, and approximately 6 to 7 months after supercharge nerve transfer.
View source ↗