Sudomotor dysfunction in patients with optic neuritis.
OBJECTIVE
Optic neuritis (ON) is a frequent initial manifestation of multiple sclerosis (MS). Autonomic failure affecting the pupillary function is known to exist in ON patients, and patients with MS are known to have more widespread autonomic dysfunction. For example, sudomotor dysfunction is well known in MS. We carried out a study investigating sudomotor abnormalities in ON patients, and later followed these patients at risk of developing MS.


METHODS
Firstly, sudomotor function was measured by sympathetic skin responses (SSRs) in 13 ON patients and in 22 healthy controls. Secondly, thermoregulatory sweating was measured by an evaporimeter after a heating stimulus in 13 ON patients and in 14 healthy control subjects.


RESULTS
The SSR latencies to electrical stimuli in the ON patients were significantly prolonged in the upper and lower extremities (p = 0.013-0.002), indicating sudomotor dysfunction. No statistically significant thermoregulatory sweating dysfunction could be found in the ON patients compared to the controls. All ON patients underwent a follow-up (mean duration 12.5 years) during which eight ON patients (62%) converted to clinically definite MS. It seemed that SSRs had no value for identifying patients who later developed MS.


CONCLUSIONS
Our results enlarge the knowledge of autonomic disorders in ON patients, showing that sudomotor function may also be involved.
Saari
Anne
A
Department of Neurology, Oulu University Hospital, Oulu, Finland. anne.saari@ppshp.fi
Tolonen
Uolevi
U
Pääkkö
Eija
E
Suominen
Kalervo
K
Jauhiainen
Jukka
J
Sotaniemi
Kyösti A
KA
Myllylä
Vilho V
VV
D000161:Acoustic Stimulation; D000328:Adult; D001342:Autonomic Nervous System Diseases / Q000473:pathology / Q000503:physiopathology*; D001833:Body Temperature Regulation / Q000502:physiology*; D001921:Brain / Q000473:pathology; D004558:Electric Stimulation; D005260:Female; D005500:Follow-Up Studies; D005712:Galvanic Skin Response / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009103:Multiple Sclerosis / Q000473:pathology / Q000503:physiopathology*; D009902:Optic Neuritis / Q000473:pathology / Q000503:physiopathology*; D012306:Risk; D013118:Spinal Cord Diseases / Q000473:pathology; D013546:Sweating / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000503:physiopathology; D014870:Water Loss, Insensible / Q000502:physiology; D055815:Young Adult