Centrale pontine myelinolyse (CPM)
- Article
- 2021-03-05
Central pontine myelinolysis (CPM) is a neurological condition that most often occurs after too rapid medical correction of sodium deficiency (hyponatraemia). The rapid rise in sodium concentration is accompanied by the movement of small molecules and draws water from brain cells. By a mechanism only partially understood, the shift of water and brain molecules leads to the destruction of myelin, a substance that surrounds and protects nerve fibers. Nerve cells (neurons) can also be damaged. Certain areas of the brain are particularly prone to myelinolysis, especially the part of the brainstem called the punch. Some people will also suffer damage in other parts of the brain, called extrapontine myelinolysis (EPM). Experts estimate that 10 percent of those with CPM will also have areas of EPM.
The first symptoms of myelinolysis, which begin to appear 2 to 3 days after hyponatraemia has been corrected, include impaired consciousness, difficulty speaking (dysarthria or mutism), and difficulty swallowing (dysphagia). Additional symptoms often occur over the next 1-2 weeks, including impaired thinking, weakness or paralysis in the arms and legs, stiffness, loss of sensation and difficulty in coordination. In its most severe form, myelinolysis can lead to coma, locked-in syndrome (which is the complete paralysis of all voluntary muscles in the body except those that control the eyes) and death.
While many affected people improve over weeks to months, some have permanent disabilities. Some also develop new symptoms later, including behavioral or intellectual disabilities or movement disorders such as parkinsonism or tremor.
Anyone, including adults and children, who undergoes a rapid rise in serum sodium is at risk for myelinolysis. Some individuals who are particularly vulnerable include those with chronic alcoholism and those who have had a liver transplant. Myelinolysis has occurred in people on kidney dialysis, burn victims, people with HIV-AIDS, people taking too many water loss pills (diuretics), and women with eating disorders such as anorexia or bulimia. The risk of CPM is higher if the serum (blood) sodium was low for a minimum of 2 days before correction.
Therapy
The ideal treatment for myelinolysis is to prevent the condition by identifying individuals at risk and following careful guidelines for the evaluation and correction of hyponatraemia. These guidelines are designed to safely restore serum sodium levels while protecting the brain. For those who have hyponatraemia for at least 2 days, or for whom the duration is unknown, the rate of elevation of serum sodium concentration should be kept below 10 mmol / L for a period of 24 hours if possible.
For those who develop myelinolysis, treatment is supportive. Some doctors have tried to treat myelinolysis with steroid medications or other experimental therapies, but none have been shown to be effective. Individuals are likely to require extensive and long-term physical therapy and rehabilitation. Those individuals who develop parkinsonian symptoms may respond to the dopaminergic drugs that work for individuals with Parkinson's disease.
Prognosis
The prognosis for myelinolysis varies. Some individuals die and others make a full recovery. Although the condition was initially believed to have a death rate of 50 percent or more, improved imaging techniques and early diagnosis have resulted in a better prognosis for many people. Most people improve gradually but still have problems with speech, walking, emotional ups and downs, and forgetfulness.
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