Question of the Week

Question :

Posted On : 26 May 2007

What is meant by central pontine myelinosis?

Expert Answer :

No expert answer available.

Answer Discussion :

Dr.Amruta

A demyelinating condition affecting the PONS and characterized clinically by an acute progressive QUADRIPLEGIA, DYSARTHRIA, DYSPHAGIA, and alterations of consciousness. Pathologic features include prominent demyelination in the central PONS with sparing of axons and neurons. This condition is usually associated with systemic disorders such as HYPONATREMIA, chronic ALCOHOLISM, LIVER FAILURE, severe BURNS, malignant NEOPLASMS, hemorrhagic PANCREATITIS, HEMODIALYSIS, and SEPSIS. The rapid medical correction of hyponatremia has been cited as a cause of this condition.

17 years ago

puru

this entity is now part of a group of disorders , osmotic dismyelination disorders

it is not pons always , affected . other parts of brain stem and and other areas also may be affected

sudden change in cellular osmolarity to either side { that is while overenthusiastic correction of hypernatremia, or vice versa can lead to these spectrum disorders
alteration of sensorium , UMN signs and almost always ocular movement and posture change. if main affection in midbrain horizonatl eye movements and if lower pons vertical .

sodium disorders are the most common { as sodium is main deciding electrolite in osmolarity , other causes of osmolarity also can lead to these type of disorders
in short the reasons and manifestations are wider ,not confined to manifestation of a pontine disorder

PURU

17 years ago

pediatriconcall

Sodium is the most important cation contributing to extracellular osmolality. Except for transient changes, the extracellular fluid and intracellular fluid are in osmotic equilibrium. Hypernatremia leads to increase in the volume of extracellular water with cerebral dehydration. Over distension of cerebral vessels leads to distension of cerebral vessels leading to subdural, subarachnoid and intracerebral hemorrhage. As a protective mechanism, the brain appears to generate new intracellular solute called as idiogenic osmoles. Intracellular osmolality is thereby increased, minimizing the loss of intracellular brain water. Rapid correction of such a hyperosmolar state may lead to excess movement of water into the cerebral cells due to the idiogenic osmoles leading to cerebral edema. Occasionally, this cerebral edema may be irreversible and fatal. Thus, a rapid rise or rapid fall in the serum sodium levels induces osmotic stress against a background of metabolic imbalance with osmotic opening of the blood-brain barrier or osmotic vascular injury. This results in cerebral edema and-or release of myelinotoxic factors which in turn may lead to demyelination and cellular injury. In adults, the osmotic vascular injury and cytotoxic edema is principally derived from the highly vascular grey matter which affects the adjacent myelinated white matter leading to demyelination of all regions in the brain, the pons has the greatest degree of grey-white apposition. Areas such as the striatum, thalamus, geniculate bodies and cerebral cortex-white matter junctions also have apposition of grey and white matter thus leading to central pontine myelinolysis {CPM}

17 years ago

praveen1699jha

demyelination of brainstem especially the pons

17 years ago

varadaraja.jonna

It is a type of neural injury in pons resulting from rapid correction of CHRONIC HYPONATREMIA resulting in confusion,agitation,flaccid or spastic quadriparessis and death.

17 years ago

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