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Aims/ Objectives: To study the importance of electrophysiological tests in diagnosing hereditary motor sensory neuropathy in absence of genetic studies.
Study Design: Cross-sectional study.
Place and Duration of Study: Department of Physiology, Pt. B.D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India.
Methodology: The patients were referred from the Department of Medicine to the Department of Physiology for nerve conduction, F-wave, EMG, VEP & BERA studies.
Results: On electrophysiological examination, there was symmetrical decreased motor conduction velocity of median nerve (less than 38 m/sec), ulnar, tibial and peroneal nerves except in the first patient where the left peroneal nerve conduction velocity was not recordable with decreased amplitude and increased distal motor latencies. Sensory conduction velocities for bilateral median nerves were also decreased with increased latency and decreased amplitude in both the patients. Sensory conduction velocity and amplitudes of bilateral sural nerves were decreased in the first patient with increased latencies. However, sensory conduction velocity wasn’t recordable for bilateral sural nerves in the other patient. EMG shows decrease in recruitment of motor unit potentials, amplitude in bilateral tibial, peroneous, abductor digiti minimi & 1st dorsal interosseus muscle in the first patient. In proximal upper & lower limb muscles, EMG showed features of denervation. In the second patient, EMG was not advised. VEP in one patient had increased latency of P100 wave & other had normal VEP. Brainstem auditory evoked potential was normal in both patients.
Conclusion: The paper highlights the importance of electrophysiological studies in diagnosis of motor sensory neuropathy in absence of genetic studies. Marked slowing of conduction velocity is the hallmark of CMDT1 [demylinating type].
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