Clinical study of primary progressive multiple sclerosis in Northern Ireland, UK

To investigate the clinical and demographic characteristics of primary progressive multiple sclerosis (PPMS) in Northern Ireland and to establish a database of such patients for genetic and immunological studies and future therapeutic trials.

Diagnosis and categorisation were performed by two neurologists, potential cases being identified from the following sources: neurology outpatient clinics; neurology inpatients; a review of hospital discharges; and an ongoing epidemiological study of multiple sclerosis in Northern Ireland. Only those with a progressive course from onset and a clear history of no prior relapses were accepted. Potential cases were invited for interview and assessment, the minimal record of disability (MRD) being established.

One hundred and eleven cases of PPMS have been identified, 63 women and 48 men (ratio 1.3:1), with a mean age at onset of 39.5 (SD 11.0) (range 17-66)years, and mean disease duration of 13.6 (SD 9.3)years. The mean interval between onset and diagnosis was 4.7 (SD 4.2) years. Nineteen patients (17.1%) did not satisfy the requirements for any category in the Poser criteria. Motor disturbance was the commonest mode of onset (67.6%) with visual loss occurring only rarely at onset (3.6%). Kurtzke EDSS scores were concentrated at the upper end of the scale with a median of 6.0 and levels of unemployment and financial dependence were high.

PPMS in Northern Ireland has a generally later age at onset, lower female preponderance, and predominantly motor onset compared with other subgroups of multiple sclerosis. The delay to diagnosis reflects the often insidious onset and the nature of the clinical course makes application of the Poser criteria difficult. Levels of neurological impairment, disability, and handicap as measured by the MRD are high.