Slurred Speech and Dysphagia Leading to Spastic Quadriplegia Following Treatment

Kaleem Ullah Toori, MBBS; Sumaira Nabi, MBBS

Disclosures

April 12, 2017

Discussion

This patient had rapid correction of his hyponatremia followed by the development of neurologic symptoms, including dysphagia and dysarthria. This was followed by spastic quadriplegia, which evolved over 2 days. The initial impression was that of a probable brainstem stroke; central pontine myelinolysis (CPM) was also considered in the differential diagnosis. An MRI of the brain with contrast revealed findings consistent with CPM.

CPM is a neurologic disorder caused by sudden, severe, noninflammatory demyelination of the brainstem, more precisely in the area of the pons. It is now typically recognized as a complication of rapid correction of hyponatremia.[1] It was first described by Adams, Victor, and Mancall[2] in 1959 when they observed a fulminant central nervous system disorder in alcoholic and malnourished patients in the form of spastic quadriplegia, pseudobulbar palsy, and varying grades of altered mentation. The association with extrapontine myelinolysis was made in 1962, and the link with rapid correction of hyponatremia was made in 1982.[3]

The exact mechanism of CPM remains elusive, but it is thought that the rapid correction of hyponatremia causes an osmotic shift of water out of the neurons, leading to shrinkage of their myelin sheaths. This, in turn, leads to compression of the tract fibers and demyelination.[4,5,6,7] The area of involvement is commonly the basis pontis, but extrapontine sites, including the midbrain, basal nuclei, thalamus, and cerebellum, may also be affected.[2,3,8] These areas are thought to be susceptible because of the close proximity of neurons, glial cells, and myelin sheaths.[9] The condition is thought to be more frequently seen in females than in males, but there is no known racial or genetic susceptibility.

Other risk factors for CPM include alcoholism, hypokalemia, malnutrition, Wilson disease, and liver transplant surgery or hematopoietic stem cell transplantation.[10,11,12] CPM may also be seen in severely burned patients.[13]

The risk for CPM by rapid correction of hyponatremia increases if the patient has a serum sodium level < 120 mEq/L for more than 48 hours, which is then briskly corrected by more than 12 mEq/L in the next 24 hours. The absolute magnitude of the change in serum sodium concentration is more important than the rate of correction. CPM is not seen in every patient who undergoes rapid sodium correction[14]; other subtle risk factors may contribute, including other electrolyte abnormalities such as hypokalemia (as was noted in this patient).

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