Endoscopic Endonasal Transclival Approach to the Ventral Brainstem: Anatomic Study of the Safe Entry Zones Combining Fiber Dissection Technique with 7 Tesla Magnetic Resonance Guided Neuronavigation.

BACKGROUND: Treatment of intrinsic lesions of the ventral brainstem is a surgical challenge that requires complex skull base antero- and posterolateral approaches. More recently, endoscopic endonasal transclival approach (EETA) has been reported in the treatment of selected ventral brainstem lesions. OBJECTIVE: In this study we explored the endoscopic ventral brainstem anatomy with the aim to describe the degree of exposure of the ventral safe entry zones. In addition, we used a newly developed method combining traditional white matter dissection with high-resolution 7T magnetic resonance imaging (MRI) of the same specimen coregistered using a neuronavigation system. METHODS: Eight fresh-frozen latex-injected cadaver heads underwent EETA. Additional 8 formalin-fixed brainstems were dissected using Klingler technique guided by ultra-high resolution MRI. RESULTS: The EETA allows a wide exposure of different safe entry zones located on the ventral brainstem: the exposure of perioculomotor zone requires pituitary transposition and can be hindered by superior cerebellar artery. The peritrigeminal zone was barely visible and its exposure required an extradural anterior petrosectomy. The anterolateral sulcus of the medulla was visible in most of specimens, although its close relationship with the corticospinal tract makes it suboptimal as an entry point for intrinsic lesions. In all cases, the use of 7T-MRI allowed the identification of tiny fiber bundles, improving the quality of the dissection. CONCLUSION: Exposure of the ventral brainstem with EETA requires mastering surgical maneuvers, including pituitary transposition and extradural petrosectomy. The correlation of fiber dissection with 7T-MRI neuronavigation significantly improves the understanding of the brainstem anatomy.

Survival outcomes following repeat surgery for recurrent glioblastoma: a single-center retrospective analysis.

The aim of the present study is to evaluate the impact of extent of resection at initial and repeat craniotomy on overall survival of patients with recurrent glioblastoma. The authors retrospectively reviewed the records of all adults patients who underwent repeat resection of recurrent glioblastoma following radiation and chemotherapy at an academic tertiary-care institution between 2011 and 2015. We evaluated the survival outcomes with regard to extent of resection considering both the initial and repeat resections. The role of possible prognostic factors that may affect survival after repeat resection, including age, preoperative performance status, tumor location and adjuvant treatment, was evaluated using Cox regression analyses. Forty-eight patients were included in this study. The overall median survival of 14 patients who had subtotal resection at recurrence after initial subtotal resection did not statistically differ from seven patients who had gross-total resection at recurrence after initial subtotal resection (18 months vs. 22 months, p = 0.583). The overall median survival of 13 patients who had gross-total resection at recurrence after initial gross-total resection was significantly increased compared with survival of 13 patients who had subtotal resection at recurrence after initial gross-total resection (47 months vs. 14 months, p = 0.009). A Cox proportional hazards model was created demonstrating that preoperative performance status at recurrence (HR 0.418, p = 0.035) and the extent of repeat resection (HR 0.513, p = 0.043) were independent predictors of survival. Gross-total resection at repeat craniotomy is associated with longer overall survival and should be performed whenever possible in patients with recurrent glioblastoma and in good performance status.