Paroxysmal phenomena are rare but relatively typical, and occasionally initial, clinical symptoms of multiple sclerosis. They should be recognized since they can serve as clinical indicators of the disease and can be treated efficiently with carbamazepine. Such shortlived clinical symptoms and signs are probably caused by ephaptic transmission due to myelinoaxonal dissociation within the demyelinated plaque. The clinical picture, pathophysiology and treatment of these disorders are discussed.