Patient- and disease-specific factors associated with atrophy of the intrinsic muscles of the ulnar nerve in cubital tunnel syndrome.

Abstract

Patients presenting with severe neuropathy are less likely to recover after surgery for cubital tunnel syndrome. The purpose of this study was to investigate patient- and disease-specific factors associated with atrophy at presentation of the intrinsic muscles innervated by the ulnar nerve. A retrospective data of patients with cubital tunnel syndrome were included in the study. Paralysis of the intrinsic muscles was evaluated as muscle atrophy of the first dorsal interossei, adductor pollicis, or abductor digiti minimi. The muscle atrophy group comprised 64 patients with atrophy of the intrinsic muscles. The non-atrophy group comprised 57 patients without intrinsic muscle atrophy at presentation. Univariate and multivariate regression analyses were conducted to assess patient factors including age, sex, body mass index, disease duration, comorbidities (diabetes mellitus and cervical spondylosis), and other elbow disorders (osteoarthritis of the elbow, presence of a ganglion, and cubitus varus or valgus deformity). A radiographic evaluation of elbow osteoarthritis was conducted using the Broberg and Morrey classification; osteophytes of the ulna were also assessed. Through univariate analysis, patients in the muscle atrophy group were identified as being significantly older, with significantly longer disease duration and more osteophytes of the ulna, than those in the non-atrophy group. Cervical spondylosis and osteoarthritis of the elbow were more frequently observed in the muscle atrophy group than in the non-atrophy group. Multivariate analysis identified patient's age as an independent risk factor related to atrophy of the intrinsic muscles, while other factors were not significant association. There was no association between the intrinsic muscle atrophy in cubital tunnel syndrome and elbow osteoarthritis. Older patients with cubital tunnel syndrome were more likely to present with atrophy of the intrinsic muscles of the ulnar nerve. Knowledge of the factors associated with severe neuropathy may allow for earlier diagnosis and therapeutic intervention.