I discuss below two topics that we don’t understand well in MS. Firstly, the diagnosis of late onset MS (LOMS). Secondly, the occurrence of stroke in MS.
Differential diagnosis in Late Onset Multiple Sclerosis (LOMS) – Marrodan et al. Neurology Dept., Fleni, Buenos Aires, Argentina
LOMS is defined as presentation beyond the age of 50 years, accounting for less than 12% of MS cases. Diagnosis is challenging as white matter lesions could be vascular instead of demyelinating, and as a result misdiagnosis is common.
Out of 149 subjects studied by Marrodan et al., only 82 were MS (55%, Figure 1) whilst 67% had other diagnosis. Among the latter 30 had a demyelinating disorder not fulfilling the criteria for MS (20%), followed 25 defined by stroke-like lesions presenting as non-specific matter lesions (17%).
Of those who met the diagnostic criteria for LOMS , myelitis (or spinal cord involvement) was the most frequent presentation (see figure 2). Other complementary findings were MRI evidence of corpus callosum lesions (Dawson-finger sign) and black holes, as well as positive oligoclonal bands (OCBs).
It is therefore not surprising that with the predominant cord involvement LOMS cases are more likely to present with walking difficulties.
Stroke diagnosis and treatment patterns in MS – Melamed et al., Montefiore Medical Center, Bronx, NY
Whilst MS is rare (US prevalence 450,000), stroke is common (US incidence 795,000 cases per year). Not surprisingly, PwMS also experience strokes, and around 1 in 10 die as a result. However, the challenge remains in the diagnosis and mistaking a stroke for an MS relapse. Moreover, co-morbidities worsen disease progression and quality of life in MS.
In a retrospective study of all strokes spanning 2009-2016 Melamed et al. identified those who had experienced a stroke with a background of MS, which amounted to 0.3%. When they compared the demographics with PwMS with stroke to non-MS with stroke, the features that stood out were that they were more likely to be women (77% vs 53%), younger (average age 63 vs 70), and in terms of risk factors were less likely to have diabetes and atrial fibrillation, but equal representation in terms of high blood pressure, high cholesterol, coronary artery disease and prior history of strokes/TIA (see Figure 3 top panel).
In terms of treatment patterns, there was no significant differences in time to presentation or receiving tPA (i.e. thrombolysis), although it looks as if they were less likely to receive the latter (see figure 3 bottom panel).
Interestingly, PwMS were more likely to have cryptogenic stroke (i.e. no identified cause) than non-MS presentations (59% vs 20%), see figure 4. In light of the complications noted in Alemtuzumab this clearly needs to be taken into consideration.