{"id":"9a69fd27-035f-4343-a825-1487f4dd7fb8","slug":"reversible-cognitive-and-gait-impairment-by-a-giant-quadrigeminal-cistern-arachnoid-cyst-a-case-report-of-marked-reversal-following-neuroendoscopic-fenestration","title":"Reversible cognitive and gait impairment by a giant quadrigeminal cistern arachnoid cyst: A case report of marked reversal following neuroendoscopic fenestration","authors":["Toshihide Takahashi","Kiyoyuki Yanaka","Akira Tamaoka","Saaya Maruyama","Hitoshi Aiyama","Aiki Marushima","Eiichi Ishikawa"],"abstract":"Background: Quadrigeminal cistern arachnoid cysts are rare in adults, but can cause reversible gait and cognitive impairment secondary to obstructive hydrocephalus. Differentiating these structural lesions from idiopathic normal-pressure hydrocephalus (iNPH) or neurodegenerative diseases is essential because they are surgically treatable. Case Description: A 71-year-old woman presented with progressive gait disturbance and mild cognitive impairment. Neuropsychological tests showed a Montreal Cognitive Assessment–Japanese version (MoCA-J) score of 21/30 and a frontal assessment battery (FAB) score of 13/18, indicating executive dysfunction. Standard cognitive screening such as mini-mental state examination did not detect the subtle deficits identified by MoCA. Magnetic resonance imaging revealed a giant arachnoid cyst in the quadrigeminal cistern compressing the midbrain and cerebral aqueduct, resulting in obstructive hydrocephalus. Endoscopic cyst fenestration was performed through a right frontal burr hole. The cyst was opened and communication with the third ventricle was achieved. Gait and cognitive functions markedly improved postoperatively (MoCA-J 26/30, FAB 17/18) and radiographic findings showed that the hydrocephalus had resolved. Ocular symptoms, including difficulty gazing upward, also resolved after surgery. Conclusion: Quadrigeminal cistern arachnoid cysts can mimic iNPH or neurodegenerative disorders, but represent a reversible cause of cognitive and gait impairments. Detailed neuroimaging and sensitive cognitive assessments are essential for diagnosis. Neuroendoscopic fenestration provides a treatment, i.e., minimally invasive and effective, even in elderly patients.","thumbnailUrl":"https://sni-digital-videos.s3.amazonaws.com/articles/9a69fd27-035f-4343-a825-1487f4dd7fb8/featured/hero-1781557810392.png","publishDate":"2026-03-13T00:00:00.000Z","doi":"10.25259/SNI_1275_2025","categories":["Neuroendoscopy","Case Report"],"fullTextUrl":"https://surgicalneurologyint.com/wp-content/uploads/2026/03/14371/SNI-17-142.pdf"}