Quantitative Analysis of the Deltoid Tendon Reflex with Evoked T-waves Applied to Diagnosis of the Level of Injury in Cervical Myelopathy

Abstract

Deltoid tendon reflexes are mainly innervated by the C5 reflex arc, and show hyperactivity in spinal cord lesions of the occipito-cervical region. The author has been using Deltoid tendon reflex in the diagnosis of the level of injury in cervical myelopathy. However the evaluation of tendon reflexes is subject to examiner bias. Therefor the author has focused attention on qualitative analysis of the tendon reflex utilizing T-wave as a method of objective evaluation. T-waves of Deltoid tendon reflex (DRT) and biceps tendon reflex (BRT) were first recorded in a contrast group of 40 healthy adults. The mean onset latency for DRT was 10.48±1.02 msec. The contrast group was divided as follows. Normal activity group : within mean onset latency ±2S.D. Hypoactivity group : over mean onset latency +2S.D. Hyperactivity group : under mean onset latency -2S.D. Then T-waves were recorded likewise in 30 upper extremities of 15 patients with cervical disorders. Electrophysiological diagnosis of the level of injury was possible in 12 of the 15 patients. In seven of these, the electrophysiological diagnosis was in concordance with the clinical diagnosis of the level of injury. Because this method can be performed at the outpatient department, is noninvasive, is relatively easy to perform, and is not subject to examiner bias, I believe that it is very useful for evaluating the pathology of high cervical lesions.