MS onset after the age of 50, can be challenging to diagnose.  Previous studies report a low prevalence of 1-9%. Challenges include misdiagnosis, lack of clinical trials and comorbidities that we often encounter in patients over the age of 50.  Herein, we described the clinical and radiographic characteristic of LOMS in our clinic population.

We performed a retrospective chart review of 314 MS patients in our clinic. MS patients with the onset after the age of 50 were included. Demographic, clinical, magnetic resonance imaging (MRI) and laboratory findings were collected and analyzed by descriptive statistics. Patients who reported having MS symptoms prior to the age of 50 were excluded.

The ongoing study, preliminary data of 50 patients (16%) were considered late onset. There was a preponderance of female patients (64%). The median age at onset was 56 years (range 50-69 years). The demographic table will be presented.  The most common clinical presentation was motor deficit 74%, sensory impairment in 70% as well as cerebellar and cerebral dysfunction in 38%. Optic neuritis was found in 18%. Spinal cord involvement was demonstrated by MRI in 44%. 55% LOMS with myelitis had multifocal lesions. MRI brain showed cortical/juxtacortical, periventricular, and infratentorial T2 lesions in 92%, 84%, and 48% retrospectively. DWI and enhancing lesions also documented.  More MRI information, clinical data, and comorbidities will be presented at the meeting. 36% of patients were misdiagnosed at the first visit. Most common misdiagnosis was stroke 50%. The motor deficit was the clinical presentation which had the highest rate of misdiagnosis at 35%.

LOMS seems to be more common than previously reported. Misdiagnosis can lead to treatment delay and increased disability. Comorbidities can interfere with the recovery and response of disease-modifying therapies. More studies in LOMS are needed.