Longstanding hydrocephalus and raised intracranial pressure can lead to unusual anatomical variants in the floor of the third ventricle, which may be important when performing endoscopic third ventriculostomy. Two middle aged patients with symptomatic longstanding hydrocephalus had scans that showed ventricular hydrocephalus, an empty sella, and a dilated infundibular recess which herniated into the sella turcica. Endoscopic third ventriculostomy confirmed that instead of the tuber cinerum and infundibular recess, the anterior inferior floor of the third ventricle was hanging down ventral to the pons into the sellar floor. Third ventriculostomy to the prepontine cistern was made on the dorsal wall of the dilated infundibular recess to the area surrounded by the dorsum sellae, the basilar artery trunk, and the left superior cerebellar artery, with good symptomatic control. Association of the empty sella and persistence of the infundibular recess must be carefully evaluated by MRI before attempting endoscopic third ventriculostomy. Herniation of the anterior inferior floor of the third ventricle into the empty sella can lead to loss of anatomical landmarks that require special attention during third ventriculostomy. (J Neurol Neurosurg Psychiatry 2000;69:531-534) Keywords: hydrocephalus; endoscopy; third ventriculostomy Endoscopic third ventriculostomy plays an important part in the treatment of hydrocephalus.1 Anatomical landmarks are well established and the procedure is safe in well experienced hands. Recently we have encountered two adult patients who were diagnosed as "long standing overt hydrocephalus in the adult (LOVA)" 2 and in whom the floor of the third ventricule was seen to be completely diVerent from the normal anatomy. We report the cases and surgical techniques, and discuss the relation between hydrocephalus, empty sella, and persistence of infundibular recess which were associated with the patients. CASE 1 A 31 year old woman had had chronic headaches, which increased in frequency and were accompanied by dizziness. Brain CT showed marked ventriculogmegaly with flat-
Case report