Anti-phospholipid antibodies in patients with multiple sclerosis and MS-like illnesses: MS or APS?

OBJECTIVE

To describe the frequency, clinical, and laboratory features of patients diagnosed with multiple sclerosis (MS) or MS-like illnesses (MSL) among a large, prospectively followed cohort of anti-phospholipid antibody (aPL)-positive patients.

METHODS

Between 1990 and 1995 patients referred to a university-affiliated rheumatology clinic were prospectively evaluated for aPL based on questionnaires designed to detect aPL-related symptoms and/or a family history of aPL-related illnesses. Magnetic resonance imaging (MRI) was performed when significant neurological features were present. A subgroup of all patients diagnosed with MS or MSL was identified and their clinical, laboratory, and imaging findings were reviewed.

RESULTS

Of 322 patients evaluated for aPL-related symptoms or events, 189 (59%) were positive for at least one class of aPL. Twenty-six of 322 patients (8%) carried a diagnosis of MS or MSL, either at the initial evaluation or during the study period. Twenty-three of the 26 individuals (88%) tested positive for aPL, while the remaining 3 (11%) tested repeatedly negative. Eighteen of the 23 patients (78%) had either more than one class of aPL or had multiple positive titers. IgM aCL was noted in 18 of the 23 patients (78%). Oligoclonal bands were noted in five patients. Antinuclear antibodies (ANA) and low complement levels were frequently observed. Blinded MRI readings showed lesions consistent with MS in the majority of cases. Clinically, 7 patients had transverse myelitis (TM), while optic neuritis (ON) was present in 8 patients. Most patients had either occult symptoms of rheumatic disease or contributory family histories. None had a defined underlying connective-tissue disease.

CONCLUSION

A substantial number of aPL-positive patients have a concurrent diagnosis of MS or MSL, frequently presenting with elevated IgM aCL, optic neuritis, and transverse myelitis. The anti-phospholipid syndrome (APS) should be strongly considered as an alternative diagnosis to MS in these patients.