#ClinicSpeak & #NeuroSpeak: sleep disorders are associated with MS relapse

Sleep disorders and MS disease activity; chicken or egg? #ClinicSpeak #NeuroSpeak #MSBlog

The study below suggests that a sleep disorder, or poor sleep, as assessed by a self-reported  sleep quality assessment is associated with relapses or focal MS inflammatory activity. The authors' suggest it is the sleep disorder that triggers the relapse. Could it be the other way around that inflammation with the brain and spinal cord (CNS) is the cause of the sleep disturbance? We know that MS disease activity clusters in time, i.e. may lesions come in a cluster. In addition, it takes weeks to months for a lesion to evolve; in other words focal changes predate the focal inflammation that causes a relapse. Could it be these changes or other lesions that cluster with relapse causing lesion, or the inflammatory mediators released into the brain that affects the neuronal circuits responsible for sleep? I would favour the latter, over the former, explanation. Please note sleep is a biological process and hence likely to be interrupted and affected by focal MS lesions and the inflammatory processes that drive MS. 

If you have developed a sleep disorder you may need to think carefully about whether or not it may be linked to MS disease activity. There are several well described cases of acute-onset narcolepsy, a well-defined sleep disorder, in pwMS due to lesions in a part of the brain called the hypothalamus. If an MS lesion can cause narcolepsy, why can't strategically located lesions not be responsible for other sleep disorders?

Sahraian et al. Sleep Disorder as a Triggering Factor for Relapse in Multiple Sclerosis. Eur Neurol. 2017 Mar 31;77(5-6):258-261.

BACKGROUND/AIMS: To determine the effect of sleep disturbances on predisposing multiple sclerosis (MS) patients for acute relapse.

METHODS: This case-control study was conducted on 80 MS patients including 40 patients in the remission phase and 40 in the relapse phase. Patients were asked to fill in the Pittsburgh Sleep Quality Index to determine their sleep quality during the previous month. Individuals with scores of 5 or less were considered having normal sleep quality.

RESULTS: Mean ± SD ages were 32.5 ± 7.7 and 30.2 ± 7.2 years among patients with and without acute relapses, respectively (p > 0.05). The mean disease duration and disease severity (according to Expanded Disability Status Scale [EDSS]) were comparable across the groups (p > 0.05). Among those with and without acute exacerbations, 87.5 and 50% had poor sleep quality, respectively (p = 0.0001), with OR of 1.75 (95% CI 1.25-2.43). The age, gender, EDSS, and disease duration did not associate with sleep quality in either groups (p > 0.05).

CONCLUSIONS: This study showed that sleep disturbance might be a trigger for an acute MS exacerbation. Increasing the awareness of specialists and routine screening of sleep disorders in MS patients are warranted, as treatment of these disorders might decrease the likelihood of acute relapses.

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