Isolated Compression of the Ulnar Nerve Motor Branch: A Case Series With 3 Unique Etiologies.

Background: Although ulnar neuropathies are commonly encountered, isolated involvement of the motor branch is exceedingly rare. Previous reports of this entity describe compression as the deep motor branch passes through the piso-hamate hiatus and the adductor pollicis hiatus. This case series described 3 cases of motor branch compression due to unique etiologies which resolved after surgery.

Methods: A retrospective chart review identified patients with compression of the ulnar nerve motor branch. From these patients, 3 were selected with a unique etiology for compression. Patient demographics, objective and subjective findings, and pathology identified during surgery were recorded and analyzed.

Results: Eight patients had compression of the ulnar nerve motor branch and 3 unique etiologies were selected; an intraneural ganglion, a constricting leash of vessels, and a series of compressing fibrous bands. All required surgery, and each patient had full resolution of symptoms by 1 year postoperatively.

Discussion: Patients presenting with complaints of weakness with a positive Froment and Egawa signs but a negative Wartenberg sign and no sensory complaints can be a diagnostic dilemma. Compression of the ulnar nerve motor branch must be considered, and here we present 3 unique cases. Activity modification in those presenting early may be curative, although many ultimately require surgery. In the cases presented here, all patients experienced full resolution of their symptoms by 1 year after surgery.