Central pontine myelinolysis scenario the CPM is caused by polydipsia leading to low blood sodium levels (hyponatremia). In schizophrenic patients with psychogenic polydipsia, inadequate thirst reception leads to excessive water intake, severely diluting serum sodium. With this excessive thirst combined with psychotic symptoms, brain damage such as CPM may result from hyperosmolarity caused by excess intake of fluids, (primary polydipsia) although this is difficult to determine because such patients are often institutionalised and have a long history of mental health conditions. It has been observed following hematopoietic stem cell transplantation. CPM may also occur in patients prone to hyponatraemia affected by: The currently
Hypotonic hyponatremia blood volume that is no longer there, that has been lost from the body. As a result, their blood volume is reduced. As mentioned above, lack of adequate blood volume is a potent stimulus for ADH secretion and thence water retention. Some patients with hyponatremia have normal or slightly elevated blood volume. In those patients, the increased ADH activity and subsequent water retention may be due to "physiologic" causes of ADH release such as pain or nausea. Alternatively, they may have the Syndrome of Inappropriate ADH (SIADH). SIADH represents the sustained, non-physiologic release of ADH and most often occurs as