Central nervous system involvement in optic neuritis.

Thirty patients with clinically uncomplicated optic neuritis were subjected to a battery of electrophysiological tests, including visual evoked response (VER), auditory brainstem evoked response (ABER) and somatosensory evoked response (SSER). Blink reflex, electronystagmography (ENG), and computed tomography examinations were also carried out on all patients. These non-invasive tests indicated that in 11 of the 30 patients (37%), the optic neuritis was a symptom of subclinical multiple sclerosis, and that another five patients showed signs of mild central nervous system (CNS) involvement which may develop into multiple sclerosis later. This was confirmed by cerebrospinal fluid (CSF) analysis, using isoelectric focusing, showing oligoclonal extra bands in 11 out of these sixteen. A new classification of optic neuritis is proposed on the basis of these findings.