The role of clinical and magnetic resonance imaging (MRI) features on
the prognosis of acute transverse myelitis has been studied, but the r
ole 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 E
MG. The outcome was defined on the basis of a 3-month Barthel Index (B
I) score as good or poor. The EMG changes in these groups were compare
d. All of the patients had complete paraplegia (power grade 0), except
1 who had grade LII power. Mild upper limb weakness was present in 6
patients. Joint position and vibration sense were impaired in the lowe
r limbs, and a horizontal limit to sensory loss to pinprick was presen
t 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 upp
er limbs in all 6 patients. The EMG changes also improved in 6 patient
s; fibrillations either disappeared or were markedly reduced. The moto
r unit potentials (MUPs) were of long duration, polyphasic with reduce
d recruitment. In 5 patients, however, no MUPs could be recorded and f
ibrillations persisted. Lower limb hypotonia and fibrillations on EMG
were significantly related to the 3-month outcome. EMG evidence of den
ervation in the lower limb muscles in acute transverse myelitis sugges
ts a poor outcome as assessed by 3-month Barthel index score.