Nerve Conduction Studies in Surgical Cubital Tunnel Syndrome Patients

Abstract

Background: Electrodiagnostic studies (EDX) serve a prominent role in the diagnostic workup of cubital tunnel syndrome (CBTS), but their reported sensitivity varies widely. The goals of our study were to determine the sensitivity of EDX in a cohort of patients who responded well to surgical cubital tunnel release (CBTR), and whether the implementation of the Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) criteria improves the sensitivity. Methods: We identified 118 elbows with clinical CBTS who had preoperative EDX and underwent CBTR. The EDX diagnoses were CBTS, ulnar neuropathy (UN), and normal ulnar nerves. We divided the 118 elbows into those that received above-elbow stimulation (XE group) and those that did not (non-XE group). We calculated the sensitivities for all groups and reinterpreted the results according to the AANEM guidelines. Results: Cubital tunnel release provided significant relief in 93.6% of the elbows. Based on the EDX reports, 11% patients had clear CBTS, 23% had UN, and 66% showed no UN. The sensitivities were 11.7% for CBTS and 34.2% for any UN. In the XE group, the sensitivity of the EDX reports for CBTS and UN climbed to 33.3% and 58.3%, respectively. When we calculated the across-elbow motor nerve conduction velocity, the sensitivity for CBTS and UN was 87.5% and 100%, respectively. The XE and non-XE groups showed no difference except for sex, bilaterality, concomitant carpal tunnel release, and obesity ( P < .05). Conclusion: Implementing AANEM guidelines results in significant improvement in correlation of clinical and electrodiagnostic findings of CBTS.

Modern Treatment of Cubital Tunnel Syndrome: Evidence and Controversy

“…Diagnostic challenges include heterogenous patient population that often present symptoms at a later stage of the disease when treatment outcomes are less reliable. In early disease, when CuTS is most reliably treated, EDX are less dependable 36 and history and physical examination can be equivocal. Therefore, it is not surprising that additional imaging modalities are being studied to assist in accurately identifying CuTS prior to demyelination, axon loss, or before further irrecoverable changes occur.…”

“…However, this variable sensitivity is the reason why EDX is not considered the gold standard for diagnosing CuTS, especially in early disease. In their study consisting of 118 patients with clinically diagnosed CuTS, Shubert et al 36 demonstrated that cubital tunnel release provided considerable relief in 94% of patients, even though EDX reports showed that only 11% of patients had clear CuTS, 23% had ulnar neuropathy, and 66% had negative findings.…”

“…34 However, the diagnostic accuracy of EDX in CuTS is highly variable and secondary to biological (ie, low elbow temperature) and technical factors. 35 Shubert et al 36 previously reported that the application of American Association of Neuromuscular and Electrodiagnostic Medicine criteria increased the sensitivity of EDX in CuTS from 33.3% to 87.5%. However, this variable sensitivity is the reason why EDX is not considered the gold standard for diagnosing CuTS, especially in early disease.…”

“Functional Outcomes of Cubital Tunnel Release in Patients with Negative Electrodiagnostic Studies”

“…Shubert et al have demonstrated that implementing American Association of Neurology and Electrodiagnostic Medicine guidelines improves the correlation of clinical and EDS findings in CuTS. 12 Normal EDSs in patients with clinical signs of CuTS could be attributable to a variety of reasons, such as technical error in performing the testing, ulnar nerve subluxation at the time of testing, 13 or if the patient is in the early dynamic ischemia stage of disease before demyelination. 14 When EDSs are positive, they are helpful in confirming the clinical diagnosis of CuTS and documenting severity.…”

Management of Recalcitrant Cubital Tunnel Syndrome

“…Electrodiagnostic studies (EDS) are used often in the diagnostic evaluation of primary CuTS. The results may be nondiagnostic in up to 66% of patients who benefit from CuTR, 28 possibly owing to the influence of dynamic compression. EDS may not fully normalize after CuTR confounding its diagnostic accuracy in recalcitrant disease.…”