Clinical Diagnosis of Coincident Carpal and Cubital Tunnel Syndromes: Level 3 Evidence

Abstract

Patients with coincident cubital tunnel syndrome can be diagnosed among patients presenting with carpal tunnel syndrome based on demographic factors, presenting symptoms, physical exam findings, and nerve conduction study results. A retrospective chart review of 515 patients was performed from patients treated for carpal tunnel release and cubital tunnel release by two university based hand surgeons. These patients were divided into cohorts as patients with isolated carpal tunnel syndrome (n=337) and patients with coincident carpal and cubital tunnel syndromes (n=178). These patients were characterized according to demographic factors, past medical history, physical exam findings, and nerve conduction study results. Univariate and multivariate logistic regression were used to select significant predictors of coincident nerve compression. The “K-B score” was constructed by converting the regression coefficients of independently predictive factors in the multiple regression model to integers for diagnosis of coincident nerve compression, after which a simplified 5 point model was chosen. A receiver operating characteristic curve was generated for each iteration of the K-B score, after which sensitivities, specificities, positive, and negative predictive values were calculated for each potential score threshold to identify the best cutoff value. Loss of intrinsic hand strength, ulnar sensation loss, positive elbow flexion test, positive cubital tunnel Tinel’s sign, and abnormal ulnar nerve NCS result were selected. The cutoff value for the K-B score was 2 points, with a sensitivity of 86.6% and a specificity of 86.5% in the developmental cohort. Area under the receiver operating characteristic curve was 0.9217. •Given the limited sensitivity and relatively high false negative rate of the NCS at the cubital tunnel, physical exam findings should weigh heavily in a diagnosis of coincident cubital tunnel syndrome in carpal tunnel syndrome patients.•Patients with a K-B score of 2 or greater should be carefully evaluated for coincident compression neuropathy.•In this developmental cohort, the K-B score was a robust method for detecting coincident cubital tunnel syndrome in carpal tunnel syndrome patients. The variables involved are routinely used to assess compression neuropathy at the cubital tunnel.•Importantly, all component factors of the K-B score (i.e. loss of intrinsic hand strength, ulnar sensory loss, positive elbow flexion test, positive cubital tunnel Tinel’s sign, and abnormal ulnar nerve NCS result) were determined to be of equivalent clinical weight in assessing patients with potential coincident compression neuropathy.View Large Image Figure ViewerDownload Hi-res image Download (PPT)