Prevalence and Impact of Obstructive Sleep Apnea in Multiple Sclerosis

BACKGROUND Multiple sclerosis (MS) is an inflammatory demyelinating neurologic disease associated with significant disability. Many pathological mechanisms are believed to drive MS, including inflammation. However, the mechanism behind progression, the major driver of disability in MS, is thought to be distinctly different. With progression, neurodegeneration and loss of neurons/axons appears to be primarily responsible. A theory of "virtual hypoxia" has been theorized, in that inflammation and demyelination cause neurons and axons to work harder, utilizing more energy. The overuse of neuron/axon energy makes it more likely that there are periods of low/absent energy availability, which drives neuron/axon degeneration and progression in MS.

It is well known that MS is associated with sleep apnea. Obstructive sleep apnea (OSA) prevalence in MS patients is approximately 58%. Sleep apnea is a disorder where lower blood oxygenation occurs during sleep. Since it is probable that low blood oxygenation would contribute to neuron/axon injury, it is possible MS patients with sleep apnea have worse neurological outcomes (clinically and radiographically).

It is possible that testing can show an effect on neuron/axon injury as well as inflammation. In addition to MRI changes that correlate with these changes, there are blood markers of neurodegeneration and inflammation including neurofilament-light (NFL) and glial fibrillary acidic protein (GFAP), now available for blood testing commercially. Elevations in such markers may be associated with sleep apnea.

This study will enable a first approximation of the prevalence of sleep apnea in MS as well as associated features of the comorbidity.

Patients will undergo a Home Sleep Test study using an at home polysomnagraphy device to help determine an accurate prevalence rate of sleep apnea in the MS population. Patients will also answer questionnaires to gain qualitative data on fatigue, sleepiness, sleep quality, restless leg syndrome risk, pain, sleep apnea risk, depression, and anxiety. Lastly, blood samples will be collected to study markers of neurodegeneration and inflammation.