Occipital Interhemispheric Transtentorial Approach for Tumors of Posterior Third Ventricular Region: Review of Surgical Results.

Background: Controversies exist regarding the ideal surgical approach for tumors in posterior third ventricular region (PTV).

Objective: To evaluate the results of occipital interhemispheric transtentorial (OITT) approach for tumors in PTV.

Materials And Methods: Thirty-three patients underwent surgery via OITT approach for PTV tumors at Sri Sathya Sai Institute of Higher Medical Sciences during the study period of 5 years (June 2011-May 2016). Ideal trajectory for OITT approach was determined by neuronavigation. Endoscope was used for removing any residual lesion at the blind spots.

Results: Postoperative magnetic resonance imaging (MRI) performed in all the patients revealed gross total or near-total (>95%) excision of tumor in 31 patients (93.9%). Preoperative neurological deficits improved either completely or significantly following excision of the tumor in 73.3% (11/15) of the patients. Outcome was good (modified Rankin scale ≤2) at discharge in 93.9% (31/33) and at a final follow-up of 3 months or more in 96.8% (30/31) of the patients. None of the patients died during the postoperative period. Complications included upgaze palsy (transient- 6.1% [2/33], persisting- 3% [1/33]), visual field defects (transient- 3% [1/33], persisting- 3% [1/33]), transient third nerve paresis (1/33-3%), transient hemiparesis (1/33-3%), operative site hematoma (1/33-3%), small posterior cerebral artery (PCA) territory infarct (1/33-3%), and small venous infarct (1/33-3%). At least one follow-up MRI could be performed in 23 patients. Final follow-up MRI revealed no recurrence or increase in the size of the residual lesion compared to postoperative images in 20 patients (20/23-87%) and large recurrence in 3 patients (3/23-13%) with high-grade lesions.

Conclusion: Gross total/near-total excision can be performed in majority of the PTV tumors through OITT approach with minimal morbidity and mortality.