Pituitary apoplexy.

Pituitary apoplexy (PA) is a clinical syndrome caused by acute haemorrhage and/or infarction of the pituitary gland, generally within a frequently undiagnosed pituitary adenoma. The sudden increase in pituitary gland volume is responsible for typical symptoms: severe headache, nausea, vomiting, visual impairment, cranial nerve palsies, deteriorating level of consciousness, and hypopituitarism. Radiological evidence, especially magnetic resonance imaging (MRI) which is the most sensitive diagnostic modality, establishes the diagnosis.