Moyamoya Syndrome Associated with Late-onset Idiopathic Aqueduct Stenosis Successfully Treated with Endoscopic Third Ventriculostomy.

Moyamoya disease (MMD) is a rare idiopathic cerebrovascular disorder that causes transient ischemic attack (TIA) and ischemic stroke in the pediatric population. Herein, we report an extremely rare case of Moyamoya syndrome (MMS) and late-onset idiopathic aqueduct stenosis, a unique form of non-communicating hydrocephalus. A 17-year-old female presented with an intractable headache and occasional faintness. Pertinent medical history included a fourth ventricle epidermoid cyst without any evidence of aqueduct stenosis, which was surgically removed when she was two years of age. The patient subsequently experienced a TIA and was diagnosed with MMD at 14 years of age. Under the definitive diagnosis of MMS associated with a brain tumor, the patient underwent surgical revascularization of the symptomatic right hemisphere without complications. Although the ischemic symptoms resolved postoperatively, a medically intractable headache with occasional faintness persisted. Serial magnetic resonance imaging ultimately revealed newly developed non-communicating hydrocephalus due to acquired aqueduct stenosis at the age of 17. After careful exclusion of the development of either or both a periventricular anastomosis and vault moyamoya vessels along the surgical route using cerebral angiography, we performed an endoscopic third ventriculostomy (ETV) via the right anterior horn without complications. A complete resolution of her chronic headache with the shrinkage of the third ventriculomegaly was observed postoperatively. In cases of MMS associated with symptomatic aqueduct stenosis, transdural collaterals on the cranial vault and periventricular collaterals should be meticulously evaluated preoperatively using cerebral angiography to safely perform an ETV.

Cystic Intracranial Recurrence of Olfactory Neuroblastoma without Accumulation on Fluorine-18-fluorodeoxyglucose Positron Emission Tomography.

A 66-year-old man underwent multimodal treatment for olfactory neuroblastoma (ONB). When he was 72 years old, a cystic intracranial lesion without accumulation on fluorine-18-fluorodeoxyglucose positron emission tomography was detected. Surgical resection was performed when the patient was 73 years old. The pathological examination revealed recurrence of ONB, and the patient underwent focal irradiation. At age 81, he presented with a second recurrence in the right occipital lobe with radiological and pathological findings similar to the prior recurrence. This case suggests that pathological confirmation should be considered in cases with atypical radiological findings following the treatment of ONB.