Study design: Observational study with sequential follow-up.
Objective: To study the role of somatosensory evoked potential (SEP) and mo
tor evoked potential (MEP) in monitoring the effect of methyl prednisolone
(MPS) therapy in acute transverse myelitis (ATM).
Setting: Tertiary care referral teaching hospital at Lucknow, India.
Methods: In the present study, nine patients with ATM whose age ranged betw
een 12 and 42 years and three of whom were females have been included. They
were subjected to clinical examination, median and tibial SEP and Central
motor conduction time (CMCT) to upper and lower limbs. The clinical and evo
ked potential studies were repeated after 7 and 90 days of intravenous meth
yl prednisolone treatment for 5 days. The outcome was defined on the basis
of a 3 month Barthel Index (BI) score into poor (BI<12) and good (BI greate
r than or equal to 12).
Results: All the patients had varying degrees of leg weakness ranging betwe
en grade 0 and 4 on the Medical Research Council scale. Upper limbs were we
ak in four patients. Pinprick and joint position sensations in the lower li
mb were impaired in all patients. Central motor conduction time to upper li
mb was abnormal in two patients and to lower limbs in eight patients. Media
n SEPs were normal in all and tibial in two patients. On the seventh day fo
llow-up, muscle power improved in six which correlated with CMCT-to tibiali
s anterior in five patients. Joint position sense improved in two patients
on the seventh day but there was no further improvement at 3 months. Tibial
SEP, however, improved in four patients on the seventh day and six patient
s at 3 months. Following methyl prednisolone therapy, both sensory and moto
r functions improved, but the improvement was more pronounced and more freq
uent at 3 months compared to that on seventh day. At a 3 month follow-up, s
ix patients had good and three poor recovery.
Conclusion: Evoked potential studies provide additional objective means for
monitoring the effect of therapy in ATM.