A bi-foraminal craniometric-guided approach to endoscopic third ventriculostomy and biopsy of a pineal tumour.

BACKGROUND: Pineal tumors are very rarely encountered, with an incidence of <1% of intracranial lesions in adults. Life-threatening hydrocephalus due to obstruction of the third ventricle can result from the location of these tumours. Endoscopic third ventriculostomy (ETV) and tumor biopsy is a safe and feasible strategy, particularly if the tumor appears benign. This mitigates the high risks of uncontrollable venous bleeding from open and stereotactic biopsies. While typically performed using either ipsilateral single or dual bur holes, the location of the tumor may require modifications to the standard endoscopic techniques. CASE DESCRIPTION: A 55-year-old male presented with signs of intracranial hypertension and was found to have obstructive hydrocephalus due to a pineal tumour. The tumour displayed a right-sided dominance when the pre-operative imaging was assessed, which would risk forniceal injury if biopsied via a right-sided burr hole. Craniometric measurements revealed a superior trajectory to the tumour via the left foramen of Monro. A biforaminal approach was performed, with a traditional ETV using a right coronal bur hole and biopsy via a left frontal bur hole. This minimized forniceal stretching and allowed a safe biopsy. CONCLUSION: The bi-foraminal approach has not been widely described in the literature but can potentially avoid morbidity with biopsy in patients with right-sided pineal tumours. We believe this technique should be considered, particularly in low-resource settings where neuroendoscopy is not commonly done, and where the use of ipsilateral single or dual-bur holes may lead to forniceal injury.