Central pontine myelinolysis
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| Central pontine myelinolysis | |
 | |
|---|---|
| Pons labeled at bottom left | |
| ICD-10 | G37.2 |
| DiseasesDB | 2198 |
| MedlinePlus | 000775 |
| MeSH | D017590 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: CPM; osmotic demyelination syndrome; osmotic myelinolysis; central pontine myelinosis
Overview
Central pontine myelinolysis is a neurologic disease caused by severe damage of the myelin sheath of nerve cells in the brainstem, more precisely in the area termed the pons. It is a complication of treatment of patients with profound, life threatening hyponatraemia. It occurs as a consequence of a rapid rise in serum tonicity following treatment in individuals with chronic severe hyponatraemia who have made intracellular adaptations to the prevailing hypotonicity. It can also occur as a complication of correcting hypernatremia too rapidly.
Pathophysiology
The currently accepted theory states that the brain cells adjust their osmolarities by changing levels of certain osmolytes like Inositol, Betaine, and Glutamine. In hyponatremia the levels of these osmolytes fall, preventing entry of free-water into cells. The reverse is true for hypernatremia. So rapid correction of sodium in hyponatremia would cause the extra cellular fluid to be relatively hypertonic. Free-water would then move out of the cells. This leads to central pontine myelinolysis. Rapid correction of hypernatremia causes water to move into cells, leading to multiple cerebral hemorrhages, equally catastrophic as osmotic demyelination.
Causes
The most common cause is the rapid correction of low blood sodium levels (hyponatremia). Over rapid correction of high levels of salt in the blood (hypernatremia) can also cause the condition.
Risk Factors
It has been postulated that one underlying cause may be the lack of a substance that is essential for brain activity and is lacking due to malnutrition. The fact that this condition is most frequently observed in patients with general ill health (alcoholism, cachexia etc.) is in accordance with this hypothesis. [1]
Diagnosis
Symptoms
- Sudden para or quadraparesis, dysphagia, dysarthria, double vision and loss of consciousness.
- Confusion, delirium
- Balance problems
- Difficulty swallowing
- Hallucinations
- Reduced alertness, drowsiness or sleepiness, lethargy, poor responses
- Speech changes, poor enunciation
- Tremor
- Weakness in the face, arms, or legs, usually affecting both sides of the body
- Locked-in syndrome where cognitive function is intact, but all muscles are paralyzed with the exception of eye blinking
MRI
Imaging by MRI demonstrates an area of high signal return on T2 weighted images.
Treatment
To avoid myelinolysis, the correction of hyponatremia should not exceed 1 mEq/L per hour. [2][3] There is no specific treatment and the syndrome is associated with high mortality and morbidity. This being a potentially avoidable disaster, following recommendations may be adhered to while maintaining sodium levels:
Hyponatremia
Correction rate=0.5-1.0meq/L/hr, with not more than 12meq/l correction in 24 hrs. If the patient has seizures (or [Na+]<115), correction can be attempted at up to 2meq/L/hr, but only till seizure activity lasts and [Na+] reaches above 125-130 meq/L.
Hypernatremia
Correct at 0.5meq/L/hr. Not more than 12 meq/L/24hrs.
References
- ↑ Adams RA, Victor M, Mancall EL. Central pontine myelinolysis: a hitherto undescribed disease occurring in alcoholics and malnourished patients. Arch Neurol Psychiatry. 1959;81:154–72. PMID 13616772
- ↑ Kleinschmidt-DeMasters BK, Norenberg MD. Rapid correction of hyponatremia causes demyelination: relation to central pontine myelinolysis. Science. 1981;211(4486):1068-70. PMID 7466381
- ↑ Laureno R. Experimental pontine and extrapontine myelinolysis. Trans Am Neurol Assoc. 1980;105:354-8. PMID 7348981
Template:Diseases of the nervous system de:Zentrale pontine Myelinolyse