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Medial thalamotomy using stereotactic radiosurgery (SRS) is a potential treatment for intractable pain. However, the ideal treatment parameters and expected outcomes from this procedure remain unclear. The aim of this systematic review is to provide further insights on medial thalamotomy using SRS, specifically for intractable pain. A systematic review was performed to identify all clinical articles discussing medial thalamotomy using SRS for intractable pain. Only studies in which SRS was used to target the medial thalamus for pain were included. For centers with multiple publications, care was taken to avoid recounting individual patients. The literature review revealed six studies describing outcomes of medial thalamotomy using SRS for a total of 125 patients (118 included in the outcome analysis). Fifty-two patients were treated for cancer pain across three studies, whereas five studies included 73 patients who were treated for nonmalignant pain. The individual studies demonstrated initial meaningful pain reduction in 43.3-100% of patients, with an aggregate initial meaningful pain reduction in 65 patients (55%) following SRS medial thalamotomy. This effect persisted in 45 patients (38%) at the last follow-up. Adverse events were observed in six patients (5%), which were related to radiation in five patients (4%). Medial thalamotomy using SRS is effective for select patients with treatment-resistant pain and is remarkably safe when modern radiation delivery platforms are used. More posteriorly placed lesions within the medial thalamus were associated with better pain relief. More studies are warranted to shed light on differences in patient responses., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Chordoma is a rare slow-growing neoplastic bone lesion. However, they show an invasive local growth and high recurrence rate, leading to an overall survival rate of 65% at 5 years and 35% at 10 years. We conducted a pooled and meta-analysis comparing recurrence rate, post-operative-complications, and survival in patients undergoing either microsurgical (MA) or endoscopic approaches (EA). Search of literature was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify surgical series of clivus chordomas published between January 1990 and March 2018 on Pubmed, Scopus, and Cochrane. Two different statistical analyses have been performed: a pooled analysis and a single-arm meta-analysis of overall recurrence rate and subgroup meta-analysis of complications in the subgroups open surgery and endoscopic surgery. After full-text screening, a total of 58 articles were included in the pooled analysis and 27 studies were included for the study-level meta-analysis. Pooled analysis-the extent of resection was the only association that remained significant (subtotal: HR = 2.18, p = 0.004; partial: HR = 4.40, p < 0.001). Recurrence was more prevalent among the surgical patients (45.5%) compared to endoscopic ones (23.7%). Meta-analysis-results of the cumulative meta-analysis showed an overall rate of recurrence of 25.6%. MA recurrence rate was 31.8% (99% CI 14-52.8), EA recurrence rate was 19.4% (5.4-39.2). CSF leak rate for the endoscopic group was 10.3% (99%CI 5-17.3) and 9.5% (99%CI 1.2-24.6) for the open surgery group. The partial removal versus total removal has an influence on recurrence rate (p < 0.001). MA recurrence rate was 31.8%; EA recurrence rate was 19.4%. The extent of resection is confirmed as a statistically significant factor affecting the risk for recurrence both with the pooled analysis and with the meta-analysis. Meta-analysis demonstrated that older patients tend to recur more than young patients, especially in surgical group.

Surgical treatment of intraventricular lesions is challenging because of their deep location, vascularization, and their complex relationships with white matter fibers. The authors undertook this study to describe the microsurgical anatomy of the white matter fibers covering the lateral wall of the atrium and temporal horn and to demonstrate how the ipsilateral interhemispheric transprecuneal approach can be safely used to remove lesions of this region sparing the anatomo-functional integrity of the fibers themselves. A detailed description of the approach including operative measurements is also given. The Klingler' technique with progressive identification of white matter fibers covering the lateral wall of the atrium and temporal horn was performed on ten formalin-fixed human hemispheres. Then, ten fresh, non-formalin-fixed non-silicon-injected adult cadaveric heads were analyzed for the simulation of the ipsilateral interhemispheric transprecuneal approach. Three illustrative cases are presented. The simulation of the interhemispheric transprecuneal approach on ten fresh non-formalin-fixed specimens showed that a 10 to 20 mm corticotomy perpendicular to the parieto-occipital sulcus at the junction with the cingulum allows a wide corridor for the exposure of the entire atrial cavity and the posterior third of the temporal horn. The ipsilateral interhemispheric transprecuneus approach represents a safe and effective option for tumors involving the atrium and the posterior third of the temporal horn.

Despite the recent progress in surgical technology in the last decades, the surgical treatment of skull base lesions still remains a challenge. The purpose of this study was to assess the anatomy of the tentorial and cavernous segment of the fourth cranial nerve as it appears in two different surgical approaches to the skull base: subtemporal transtentorial approach and pretemporal fronto-orbito-zygomatic approach. Four human cadaveric fixed heads were used for the dissection. Using both sides of each cadaveric head, we made 16 dissections: 8 with subtemporal transtentorial technique and 8 with pretemporal fronto-orbito-zygomatic approach. The first segment that extends from the initial point of contact of the fourth cranial nerve with the tentorium (point Q) to its point of entry into its dural channel (point D) presents an average length of 13.5 mm with an extremely wide range and varying between 3.20 and 9.3 mm. The segment 2, which extends from point D to the point of entry into the lateral wall of the cavernous sinus, presents a lesser interindividual variability (mean 10.4 mm, range 15.1-5.9 mm). A precise knowledge of the surgical anatomy of the fourth cranial nerve and its neurovascular relationships is essential to safely approach. The recognition of some anatomical landmarks allows to treat pathologies located in regions of difficult surgical access even when there is an important subversion of the anatomy.