Interhypothalamic Adhesion as Cause of Aborted Third Ventriculostomy: Neuroradiologic and Neuroendoscopic...

Interhypothalamic adhesions (IHAs) 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.

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 not performed because of the presence of a thick IHA, which prevented an approach to the floor of the third ventricle. During the procedure the patient also experienced supraventricular tachycardia. 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.

MR imaging allows one to preoperatively identify most anatomic anomalies of the ventricular system and 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.