Introduction:Transsphenoidal resection of pituitary tumors is a surgery performed through the nose and sphenoid sinus to remove pituitary tumors. Disorders of sodium balance are common after transsphenoidal surgery involving the pituitary gland. Here, we report the clinical features of an original case of acute onset parkinsonism later confirmed to be secondary to transsphenoidal resection of pituitary adenoma.Patient concerns:A 36-year-old female had received transsphenoidal pituitary resection for pituitary adenoma. Eight days after the surgery, she suffered from acute onset general weakness and nausea/vomiting. She was diagnosed with hyponatremia for which she was treated. Acute onset ataxia, bilateral hand tremor, and dysarthria were then noted on the 4th day of hyponatremia treatment.Diagnosis:Based on history, clinical manifestation, and MRI brain images, a diagnosis of acute parkinsonism caused by isolated extrapontine myelinolysis (EPM) was made.Interventions:Patient was treated with levodopa/carbidopa.Outcomes:Patient's symptoms and signs improved gradually and 2 month follow-up MRI brain showed significant resolution of the bilateral lentiform nuclei hyperintensities on the T2-weighted images. Her neurological deficits had subsided completely.Lessons:This case highlights an unexpected association between transsphenoidal resection of pituitary tumors and acute parkinsonism which is a treatable manifestation of EPM. Correction of hyponatremia following transsphenoidal pituitary resections should be preceded cautiously because even gradual correction of hyponatremia can produce myelinolysis.

Introduction:Moyamoya disease (MMD) and posterior reversible encephalopathy syndrome (PRES) share similar pathophysiological characteristics of endothelial dysfunction and impaired cerebral autoregulation. However, there have never been any published studies to demonstrate the relationship between these 2 rare diseases.Patient concerns:A 26-year-old Asian man presented with a throbbing headache, blurred vision, and extremely high blood pressure. We initially suspected acute cerebral infarction based on the cerebral computed tomography, underlying MMD, and prior ischemic stroke. However, the neurological symptoms deteriorated progressively.Diagnosis:Cerebral magnetic resonance imaging indicated the presence of vasogenic edema rather than cerebral infarction.Interventions and outcomes:An appropriate blood pressure management prevents the patient from disastrous outcomes successfully. Cerebral magnetic resonance imaging at 2 months post treatment disclosed the complete resolution of cerebral edema. The patient's recovery from clinical symptoms and the neuroimaging changes supported the PRES diagnosis.Conclusion:This report suggests that patients with MMD may be susceptible to PRES. It highlights the importance of considering PRES as a differential diagnosis while providing care to MMD patients with concurrent acute neurological symptoms and a prompt intervention contributes to a favorable clinical prognosis.