The spectrum of central nervous system–idiopathic inflammatory demyelinating disease (CNS-IIDD) in the elderly is uncertain.

To describe the clinical, radiological, and pathological features of a cohort of 30 pathologically proven CNS-IIDD patients >=65 years.

Elderly multiple sclerosis (MS)/clinically isolated syndrome (CIS) patients were compared to a cohort of 125 patients with pathologically proven MS/CIS and symptom onset <65 years.

Median age at symptom onset was 69 years (interquartile range (IQR) = 68–75). Median follow-up was 1.9 years (IQR = 1.0–5.6). Diagnoses were MS (14/30), CIS (11/30), neuromyelitis optica (NMO; 4/30), and acute disseminated encephalomyelitis (ADEM; 1/30). Disability was higher in patients with MS/CIS >=65 compared to patients <65 (median Expanded Disability Status Scale (EDSS) 4 (IQR = 2.5–7) vs 2.5 (IQR = 1.5–4); p = 0.002). When compared to patients <65 years, there was no difference in the lesion size, number of patients fulfilling Barkhof’s criteria, edema, or mass effect. Confluent demyelination was observed in 27 patients (MS/CIS (23/25), NMO (4)), 2 had a mixed perivenular/confluent pattern (MS (1), ADEM (1)), and 1 patient with MS had a mixed confluent/perivenular/coalescent pattern. Early active lesions were found in 19/30 patients ((MS (4), CIS (13), NMO (2); 53%). Cortical demyelination was present in 7/12 (58%) patients (MS (3), CIS(3), ADEM (1)).

A spectrum of CNS-IIDD can develop in the elderly, with presenting symptoms similar to younger patients. Early diagnosis of CNS demyelinating disease is essential to avoid invasive and disabling procedures.