Although relatively uncommon, other paroxysmal symptoms are highly characteristic of MS and include paroxysmal dysarthria and ataxia, tonic spasms, and paroxysmal sensory symptoms. These symptoms are thought to relate to ephaptic transmission; they last less than 2 minutes but may occur frequently (sometimes up to 20 to 30 times a day) for a 2- to 6-week period. They are exquisitely sensitive to carbamazepine, and a small study has suggested that gabapentin may be a useful alternative. Bromocriptine also has been mentioned in case reports.

Epilepsy occurs in about 5 percent of people with MS, and although this may be coincidental in some cases, there is evidence to suggest that it relates to either cortical or subcortical lesions or very large plaques that behave like space-occupying lesions and usually occur in advanced disease. Treatment should be with anticonvulsants, although their use need not always be prolonged, particularly if there is only a short cluster of attacks in association with an acute inflammatory lesion that subsequently resolves.