Neurophysiological studies in acute transverse myelitis

A systematic evaluation of anterior horn cell, motor and sensory pathways i s possible by electromyography (EMG), motor (MEPs) and somatosensory (SEPs) evoked potentials, respectively, which may provide valuable information on acute transverse myelitis (ATM). In a prospective hospital-based study, EM G, MEP and SEP studies were carried out on admission and after 3 months in 39 patients with ATM. All the patients also underwent detailed clinical eva luation, and spinal magnetic resonance imaging (MRI) was performed in 28. O utcome was defined at the end of 3 months as poor, partial or complete reco very on the basis of functional status. Spinal MRI revealed hyperintense si gnal changes in T2 extending for two segments to the entire spinal cord. Ce ntral motor conduction time to tibialis anterior (CMCT-TA) was more frequen tly abnormal (90 %), followed by tibial SEP (77 %). CMCT to abductor digiti minimi (ADM) was abnormal in 30 % and median SEP in 15 % of patients. Evid ence of denervation on EMG was present in 51 % of patients. The CMCT-TA imp roved in 48 % patients and tibial SEP in 32 %. Median SEP improved in all p atients, and CMCT-ADM remained prolonged in two. At 3 months 2 patients had died, and 18 had poor, 10 partial and 9 complete recovery. CMCT was correl ated with muscle power, tone, reflex and MRI changes. Patients' outcome of was correlated with CMCT, SEP and EMG. These results are consistent with pr onounced involvement of dorsal region of spinal cord in ATM. MEP is more fr equently abnormal than SEP.