Blake's pouch cyst is a congenital disease in which the ventricle enlargement is a non-communicating hydrocephalus. Some elderly patients have a process of the idiopathic normal pressure hydrocephalus (communicating hydrocephalus). We report an elderly patient with Blake's pouch cyst. A 68-year-old man visited our hospital with a gait disturbance that had begun 2 years previously but had become aggravated. He did not have dementia or urinary disturbance. CT scan and MRI showed the hydrocephalus included an IV ventricle, and the cerebrocerebellar fluid space in the posterior fossa was large. A Tap test was positive, so we attempted lumboperitoneal shunt, and his gait disturbance improved.
Keywords: Blake’s pouch cyst; Lumboperitoneal shunt; idiopathic normal pressure hydrocephalus.