Electrophysiologic Findings of Ulnar Neuropathy at the Elbow According to the Level of the Lesion

OBJECTIVE: To determine whether electrophysiologic findings of ulnar neuropathy at the elbow (UNE) are associated with anatomic location or a pathophysiologic mechanism, electrophysiologic findings of ulnar neuropathy above the elbow (UNAE) and below the elbow (UNBE) were compared. METHOD: Electrophysiologic findings of 56 patients with UNE were analyzed: segmental ulnar motor conduction study with abductor digiti quinti (ADQ) and first dorsal interosseous (FDI) recordings, ulnar and dorsal ulnar cutaneous nerve (DUCN) sensory action potentials, and needle electromyographic findings. Based on anatomic location, lesions were divided into UNAE and UNBE. Based on pathophysiologic findings, they were classified into three groups (focal demyelination, axonal degeneration, and mixed lesion). RESULTS: Twenty-eight patients were diagnosed with UNAE, and 28 with UNBE. Of the patients with UNAE, 4 had focal demyelination, 2 showed axonal degeneration, and 22 were of mixed lesions. Of patients with UNBE, 5 had focal demyelination, 6 showed axonal degeneration, and 17 were of mixed lesions. No significant differences in pathophysiologic mechanisms, or in electrophysiologic findings, were observed between UNAE and UNBE. The proportion of positive findings of focal demyelination was higher in FDI recording than in ADQ recording; however, this finding was not statistically significant (p>0.05). Thirty of 31 patients with abnormal DUCN had axonal degeneration with or without focal demyelination, whereas 9 of 25 patients with normal DUCN had focal demyelination only (p<0.05). CONCLUSION: Electrophysiologic findings did not relate to the anatomic location of UNE, but could relate to the pathophysiologic severity or fascicular involvement of the lesion.

Prevalence and Risk Factors of Ulnar Neuropathy at the Elbow in a Rural Population

OBJECTIVE: The purpose of this study was to investigate the prevalence and risk factors of ulnar neuropathy at the elbow (UNE) in a rural district in Korea. METHOD: Among the 578 residents in a rural district who participated in the health examination, 450 (116 male, 334 female) adults were randomly selected. A symptom questionnaire and electrodiagnostic studies were used to diagnose UNE. General characteristics, female-related factors, work-related factors and anthropometric measurements were compared between normal and UNE group to identify the risk factors of UNE. RESULTS: Subjects with UNE were 29 (6.4%), symptom without electrodiagnosis findings 23 (5.1%), asymptomatic subjects were 379 (84.2%). Diabetes mellitus, repetitive heavy lifting were risk factors of UNE. CONCLUSION: The prevalence of UNE was 6.4% in a rural district and these data suggest that medical conditions like diabetes mellitus and physical factors like repetitive heavy lifting are risk factors of UNE.