Mysathenia gravis is a chronic autoimmune neuromuscular disease that causes muscle weakness and fatigue. The condition affects one in 10,000 Americans between the ages of 20 and 40 and women are 1.5 times more likely to be affected by mysathenia gravis compared to men.
Symptoms may include:
- Slow or slurred speech
- Eyelid drooping and double vision
- Difficulty chewing and/or swallowing
Over the longer term, mysathenia gravis can weaken the muscles that control breathing, leading to sleep disordered breathing (SDB).
A systematic review published in the Journal of Physical Therapy Science identified a number of studies that found mysathenia gravis to be associated with poor sleep quality, excessive daytime sleepiness, and restless legs syndrome.
Additional research published in Neurology found that 36 percent of those with mysathenia gravis suffered from obstructive sleep apnea, compared to between 15 to 20 percent in the general population.
Sleep disordered breathing in patients with mysathenia gravisA study published in _Acta Neurologica Scandinavica _aimed to find out what causes sleep disordered breathing in patients with mysathenia gravis by studying 59 individuals with mysathenia gravis but no respiratory symptoms.They found that 24 participants had definitive sleep disordered breathing. In half of these individuals, the SDB was mild. For a quarter, the SDB was moderate, and for the other quarter the SDB was severe.Researchers identified the following four predictors of risk: 1. Body Mass Index (BMI):
A higher BMI was associated with a higher risk of SDB.
Older individuals were more likely to experience SDB.
Men were more likely than women to experience SDB.
4. Use of azathioprine:
Those who took the drug were more likely to experience SDB.
It's important to note that these predictors of risk are not necessarily causes of sleep disordered breathing in those with mysathenia gravis. For example, it seems unlikely that azathioprine has a direct effect on sleep. Rather, this is likely to be a risk factor because those who take azathioprine are likely to be doing so because they have more severe symptoms.
The authors of this study found BMI to be the most significant predictor of sleep disordered breathing. This makes sense when you consider the link between high BMI and apnea sleep disorders.
Weight control is, therefore, likely to be the simplest and most beneficial way to avoid (or reverse) sleep disordered breathing in individuals with mysathenia gravis.
Continuous positive airway pressure (CPAP) therapy can also be beneficial for those with obstructive sleep apnea. If you suspect your sleep is suffering as a result of your mysathenia gravis, be sure to raise your concerns with your doctor. Sleep issues should never be ignored.
1. Oosterhuis H. Myasthenia gravis. Groningen, Netherlands: Groningen Neurological Press; 1997.