Can electromyography predict the prognosis of transverse myelitis?

Abstract

The role of clinical and magnetic resonance imaging (MRI) features on the prognosis of acute transverse myelitis has been studied, but the role of electromyography (EMG) changes, although reported, has not been investigated. Seventeen patients with acute transverse myelitis were subjected to clinical evaluation, MRI scanning and concentric needle EMG. The outcome was defined on the basis of a 3-month Barthel Index (BI) score as good or poor. The EMG changes in these groups were compared. All of the patients had complete paraplegia (power grade 0), except 1 who had grade III power. Mild upper limb weakness was present in 6 patients. Joint position and vibration sense were impaired in the lower limbs, and a horizontal limit to sensory loss to pinprick was present in all of the patients. Spinal MRI was abnormal in 12 of 14 patients. EMG of the lower limb muscles in the acute stage (within 15-30 days of onset) revealed fibrillations or sharp waves or both in 11 patients. At 3-month follow-up, the lower limb power had improved in 8 and upper limbs in all 6 patients. The EMG changes also improved in 6 patients; fibrillations either disappeared or were markedly reduced. The motor unit potentials (MUPs) were of long duration, polyphasic with reduced recruitment. In 5 patients, however, no MUPs could be recorded and fibrillations persisted. Lower limb hypotonia and fibrillations on EMG were significantly related to the 3-month outcome. EMG evidence of denervation in the lower limb muscles in acute transverse myelitis suggests a poor outcome as assessed by 3-month Barthel index score.