Q: My 59 years old wife is suffering from multiple sclerosis. She developed viral encephalitis and was admitted to a hospital. Is there a link between viral encephalitis and multiple sclerosis?

A:There is no direct association between multiple sclerosis and viral encephalitis. These two are radiological "differential diagnoses" of each other, meaning the MRI of brain may show similar changes in either. However, the features of these two entities are quite different, and the clinicians are usually able to differentiate these based upon the history and examination of the patient.

Patients of multiple sclerosis who are on immunomodulatory therapy like interferons, monoclonal antibodies etc may have altered immune responses and thereby may be predisposed to certain unusual infections, especially viral. Let your doctor know if the patient was taking any treatment (medicines/injections) for multiple sclerosis (especially Natalizumab / Tysabri).

Tests like Cerebrospinal Fluid Examination (examination of the fluid around the spinal cord by a procedure called lumbar puncture) and serology etc can help us diagnose viral encephalitis, and there are certain useful antiviral medicines for the treatment once diagnosis is made. Her multiple sclerosis symptoms may worsen or she may have an attack after two to three weeks of any infective illness, she needs to be observed for this.