Motor Evoked Potential and Somatosensory Evoked Potential Studies in Acquired Demyelinating Polyneuropathy

후천성 탈수초성 다발신경병증에서의 운동유발전위 및 체성감각유발전위 연구

Background and Objectives: The proximal and distal nerve segments are preferentially involved in acquired demyelinating polyneuropathies (ADP). This study was undertaken in order to assess the usefulness of motor evoked potential (MEP) and somatosensory evoked potential (SSEP) in the detection of the proximal nerve lesion in ADP. Methods: MEP, SSEP and conventional NCS were performed in 6 consecutive patients with ADP (3 AIDP, 3 CIDP). MEP was recorded from abductor pollicis brevis and abductor hallucis using magnetic stimulation of the cortex and the cervical/lumbar spinal roots. SSEP were elicited by stimulating the median and posterior tibial nerves. Latency from cortex and cervical/lumbar roots, central motor conduction time (CMCT), EN1-CN2 interpeak latency were measured for comparison. Results: MEP was recorded in 24 limbs (12 upper and 12 lower limbs) and SSEP in 24 limbs (12 median nerve, 12 posterior tibial nerve). F-wave latency was prolonged in 25 motor nerves (25/34, 73.5%). Prolonged CML and PML were found in 41.7% (10/24) and 45.8% (11/24), respectively. Interside difference (ISD) of CMCT was abnormally increased in the upper extremity, 66.7% (4/6 pairs) in case of CML-PML. EN1-CN2 interpeak latency was abnormally prolonged in one median nerve (1/10) and LN1-P1 interpeak latency was normal in all posterior tibial nerves. Conclusions: MEP and SSEP may provide useful information for the proximal nerve and root lesion in ADP. MEP and SSEP is supplemental examination as well as complementary to conventional NCS.