Paroxysmal attacks in multiple sclerosis.

Twenty-two out of 235 patients with undoubted or suspected MS, treated at the Neurological Clinic, Uppsala, during the eight-year period, 1966-1973, had paroxysmal symptoms during the course of their disease. Paroxysmal dysarthria and ataxia (7 cases), and tonic seizures (5 cases) were the most common types of attacks. Some types of attacks (paroxysmal hemiataxia and crossed paraesthesiae, paroxysmal itching, diplopia as the single, paroxysmal symptom) do not seem to have been described previously. A patient with tonic seizures caused by a localized, traumatic lesion of the cervical spinal cord is also described. It is suggested that the paroxysmal phenomena in MS are caused by a transversely spreading ephaptic activation of axons within a partially demyelinated lesion in fibre tracts somewhere in the central nervous system. The different paroxysmal phenomena are discussed in the light of this hypothesis.