Motor evoked potential is useful for monitoring the effect of collar therapy in cervical spondylotic myelopathy

Abstract

Motor and somatosensory evoked potential changes are reported in 20 patients with cervical spondylotic myelopathy following 6 and 12 weeks of collar therapy. The age of the patients ranged between 35 and 69 years and one of them was a female. Walking difficulty was present in 18 and their leg weakness ranged between grade 2 and 4 on the 0-5 MRC (Medical Research Council) scale. Joint position sense was impaired in 14 patients. Central motor conduction time to tibialis anterior (CMCT-TA) was prolonged in 18 patients (30 sides) and tibial somatosensory conduction time was abnormal in seven patients (11 sides), which was unrecordable in four (seven sides). Nineteen patients were followed up for 6 weeks and 10 for 12 weeks of collar therapy. One Nurick's grade improvement occurred in 12 and two grades in three patients at 6 weeks. The CMCT improvement was noted in 15 patients (25 sides) which was associated with clinical improvement in 12 patients. At 3 months, further clinical improvement occurred in four patients whereas CMCT improved in six (nine sides) out of 10 patients followed up. At 6 weeks follow-up, tibial CSCT improved in 11 patients (17 sides) which correlated with improvement in sensations in seven patients. At 12 weeks further improvement in tibial CSCT was noted in two patients only (two sides). Central motor conduction time was more sensitive compared to CSCT for the evaluation of spondylotic myelopathy and the improvement was more pronounced at 6 compared to 12 weeks after collar therapy.