Clinical and evoked potential changes in acute transverse myelitis following methyl prednisolone

Observational study with sequential follow-up.

To study the role of somatosensory evoked potential (SEP) and motor evoked potential (MEP) in monitoring the effect of methyl prednisolone (MPS) therapy in acute transverse myelitis (ATM).

Tertiary care referral teaching hospital at Lucknow, India.

In the present study, nine patients with ATM whose age ranged between 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 evoked potential studies were repeated after 7 and 90 days of intravenous methyl 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>/=12).

All the patients had varying degrees of leg weakness ranging between grade 0 and 4 on the Medical Research Council scale. Upper limbs were weak in four patients. Pinprick and joint position sensations in the lower limb were impaired in all patients. Central motor conduction time to upper limb was abnormal in two patients and to lower limbs in eight patients. Median SEPs were normal in all and tibial in two patients. On the seventh day follow-up, muscle power improved in six which correlated with CMCT-to tibialis 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 patients at 3 months. Following methyl prednisolone therapy, both sensory and motor functions improved, but the improvement was more pronounced and more frequent at 3 months compared to that on seventh day. At a 3 month follow-up, six patients had good and three poor recovery.

Evoked potential studies provide additional objective means for monitoring the effect of therapy in ATM.