Neurophysiological Grading of Ulnar Nerve Entrapment Across wrist and Across Elbow

Abstract

Ulnar nerve entrapment across the elbow (UNEAE) and across the wrist (UNEAW) is the second most common entrapment of the hand after carpal tunnel syndrome. There are few grading available for UNEAE and fewer in UNEAW. None of those gradings compares the involvements of both (wrist and elbow). None of the literature looks at the involvement of sensory axonal neuropathy in different stages. The aim of this research are;1. To see the relation of sensory nerve involvement across the wrist with the entrapment across the elbow and to evaluate its effectiveness in each level without going for any invasive tests like needle EMG examination. 2. To identify the lesion below and across the wrist in terms of support, the clinical Physiologist (CP) grades them properly and helps the consultant decide to treat with conservative or surgical treatment.3. To compare the recording from the first dorsal interosseous (FDI) muscles with the abductor digiti minimi (ADM) muscle to see which muscle is more sensitive and shows early changes in ulnar nerve entrapment. 4. To differentiate the grading of Guyon’s canal with sensory entrapment below the wrist.5. To analyse the severity of entrapment in both areas (below/across wrist and elbow).The proposed revised grading system is based on more nuanced, descriptive categories, ranging from "early”, "mild”, "moderate” and "severe”. To create a full grading system of UNEAW and UNEAE some additional clinical grading is proposed.Method: Data was collected based on the extensive and detailed grading system previously described by Padua. The tests were performed by a qualified clinical physiologist (neurophysiology) using a Key Point 9033A07 machine, used in line with the departmental protocol (peripheral protocol 1, 2022). The Association of Neurophysiological Scientists (ANS) and British Society of Clinical Neurophysiology (BSCN) (2014) guidelines and minimum standards for the practice of clinical neurophysiology in the United Kingdom were followed. All data was recorded numerically to ensure methodological reliability.Result: The data was collected over one year six months from January 2022 till June 2023. A total of 313 abnormal hands and 200 normal hands were included in this study. Martin Gruber anomalies, which are normal variant, are not included in this study. Out of 313 abnormal hands, 149 hands were right hands and 164 were left hands. 46 hand shows lesion below the wrist and 56 hands shows lesion around Guyon’s canal. Across the elbow shows more mild cases as compared to early, moderate, and severe cases. Moderate ulnar nerve lesion across the elbow are more associated with sensory axonal and double crush cases, which were seen more in mild and moderate cases compared to early and severe cases. Conclusion: Findings show that FDI is more sensitive compared to ADM to recording early changes in ulnar nerve entrapment across the elbow. Additionally, the results show that sensory axonal involvement and double crush syndrome need to be included in the grading system which is not accounted for in any present research publication.