Interhypothalamic adhesion as a cause of aborted third-ventriculostomy: neuroradiological and neuroendoscopic considerations in a pediatric case.

BACKGROUND: Interhypothalamic adhesions (IHA) are horizontally oriented parenchymal bands of tissue connecting the medial hypothalamic regions across the third ventricle. They can be assessed with high resolution magnetic resonance (MR) techniques.

CASE DESCRIPTION: We report MR and neuroendoscopic features of IHA in a 3-year old boy without symptoms referable to the hypothalamus. He presented with obstructive hydrocephalus secondary to posterior fossa tumor. An endoscopic third ventriculostomy (ETV) was attempted but was not performed because of the presence of a very thick IHA, that prevented approach to the floor of the third ventricle. During the procedure the patient also experienced supraventricular tachicardia. The procedure was aborted and an external ventricular drainage was left in the ventricles, until resolution of hydrocephalus after posterior fossa surgery. To the best of our knowledge, no study has previously described in detail endoscopic images of IHA.

CONCLUSIONS: MR imaging allows to preoperatively identify most anatomic anomalies of the ventricular system and of the floor of the third ventricle. However an IHA that may prevent an approach to the floor of the third ventricle due to his thickness, may be missed. This can be recognized only on direct vision, underlining the importance of endoscopy in neurosurgery.