Supracerebellar infratentorial approach with paramedian expansion for posterior third ventricular and pineal region lesions.

BACKGROUND: Surgical treatment for lesions in the posterior third ventricle is technically challenging. Surgical approaches to this area carries a risk of both venous and neural injury, with subsequent morbidity. Several approaches are used to reach the pineal region. The supracerebellar infratentorial approach is the commonly approach used for such lesions.

OBJECTIVES: This work describes adding a paramedian expansion to the "classical median supracerebellar infratentorial approach" for posterior third ventricular and pineal region lesions with lateral expansion. This study discusses the results concerning the extent of removal and surgical complications for this procedure. Contralateral paramedian expansion is used for targeting lesions inside the posterior third ventricle extending to the lateral ventricular wall and thalamus. Ipsilateral paramedian expansion was used in resecting collicular lesions.

METHODS: The authors operated on patients suffering from lesions in the pineal region using a paramedian expanded SCTT approach between 2007 and 2014. The prone position was used in 25 cases. A typical median suboccipital craniotomy with a paramedian expansion was performed. Ipsilateral expansion of the approach has been used for targeting lesions in the pineal region but outside the posterior third ventricle. Contralateral expansion provides a direct view of the lateral walls of the third ventricle.

RESULTS: We encountered 28 cases of different pathologies: fourteen patients suffered from pineal body tumors while twelve had glial tumors, one case of cavernoma. Obstructive hydrocephalus was treated by CSF diversion before tumor surgery. Postoperative complications included ataxia, double vision, and Parinaud's syndrome.

CONCLUSION: The merit of the expanded supracerebellar infratentorial approach is adding a unilateral paramedian expansion to the classical approach. This paramedian expansion offers a better lateral and inferior tumor resection. This approach does not add any risk of more postoperative complications or jeopardizing the neurological state than the classical midline approach.

PRACTICE AND IMPLICATIONS: The paramedian expansion offers a better lateral and inferior tumor resection and a better view of the contralateral extension within the posterior third ventricle. Collicular lesions are better controlled using this approach by gentle inferior and lateral retraction of the cerebellum. The expanded supracerebellar infratentorial approach allows for working on the lateral tumor extension without jeopardizing the deep venous system.