Paroxysmal itching in multiple sclerosis.

In three women with multiple sclerosis, paroxysmal attacks of itching occurred. There were several similarities between these attacks and other types of paroxysmal phenomena previously described in multiple sclerosis. The attacks were brief, but usually lasted several minutes, they started and ended abruptly, and recurred several times a day. The were controlled effectively by carbamazepine. It is suggested that paroxysmal itching is caused by transversely spreading ephaptic activation of axons within a partially demyelinated lesion in pain-conducting fibre tracts in the central nervous system.