Central pontine myelinolysis following saline treatment of a diabetic rat for dehydration.

Central pontine myelinolysis (CPM) was observed at necropsy in an emaciated 333-day-old BB Wistar insulin-dependent diabetic rat that had been treated for dehydration by subcutaneous injection of normal saline. There was a large area of nearly complete demyelination involving most of the basal portion of the pons, part of the tegmentum, and the base of the middle cerebellar peduncles. There was a relative sparing of neurons and axons, but some unidentifiable large cells with degenerative changes in the cytoplasm were present. No oligodendrocytes or reactive astrocytes were seen and there was no evidence of inflammation or infarction. Although diffuse demyelination can be induced in rats by rapid fluctuation of serum electrolytes, no studies have experimentally induced central pontine myelinolysis nor has it been observed incidentally in animals previously.