P28-F The median nerve’s sonographic longitudinal diameter is quite stable in healthy volunteers

Abstract

Background Carpal tunnel syndrome is a well known entity. Patients are shared within multiple clinical specialities both surgical and medical. The true difficulty lies not within diagnosing the syndrome but in distinguishing between pt’s that will benefit from surgery from the ones were a more conservative approach could be preferred. The diagnosis is usually made clinically and supported by nerve conduction studies (EDX). In our clinic high resolution ultrasound (HRUS) is gaining territory when the clinical picture is not “clean cut”. The current study is a collection of normative data on the sonographic appearance of the normal median nerve under the ligament in the carpal tunnel in asymptomatic volunteers. Material and methods 46 healthy age grouped volunteers were screened with a Boston questionnaire as well as clinical and with EDX. Afterwards they underwent sonography with measurements of the median nerve under the ligament. All measurements were made by a skilled expert. The median nerve was visualized longitudinally aligned and the maximum and minimum diameter was noted as well as the wrist-to forearm ratio. Results The greatest difference between the maximal and minimal longitudinal diameter in all subjects was 0.5 mm (calculations Will follow). We chose to express the difference as a ratio between the minimal diameter and the proximal diameter. Mean ligament to wrist ratio was 0.93. Standard deviation was 0.097 resulting in a lower limit of 0.74. Conclusions The median nerve diameter is quite uniform in healthy volunteers without much difference in longitudinal diameter. and a notch sign indicates pathology.