Deep-seated astrocytomas within the basal ganglia and the thalamus are considered unfavourable for microsurgical removal since the circumferential neighbourhood of critical structures limits radical resection. On closer assessment, the thalamus has a unique configuration within the basal ganglia.

Its tetrahedric shape has 3 free surfaces and only the ventrolateral border is in contact with vital and critical functional structures, e.g. the subthalamic nuclei and the internal capsule.

see Transcallosal approach.

Tumors here are usually treated with biopsy and adjuvant therapy with relatively poor results. Rarely do patients undergo extensive surgical intervention. It seems reasonable to suggest that successful cytoreduction may help these patients. However, this hypothesis has not been studied due to the general view that it is not possible to remove deep-seated brain tumors with acceptable outcomes.

Through retrospective data collection, Briggs et al., described a small case series undergoing awake contralateral, transcallosal approach surgery for deep-seated brain tumors affecting the basal ganglia. They described the patient cohort, report on patient outcomes, and described the surgical technique.

Four patients underwent awake contralateral, transcallosal surgery for glioblastoma invading the basal ganglia. All four patients demonstrated hemibody weakness contralateral to the side of their tumor, with three patients confined to wheelchairs at presentation. Ages ranged from 25-64 years. Tumor volumes ranged from 14-93 cm3. Greater than 50% resection of each tumor was achieved during surgery. In two cases, approximately 90% resection was achieved. Motor strength improved in one patient who presented with hemiplegia. Two patients required ventriculoperitoneal shunting for complications related to hydrocephalus. When writing this manuscript, two of our patients were still alive, functional, and free of tumor progression.

They presented results attempting to resect large gliomas infiltrating the basal ganglia in four patients. This technique combined a contralateral, transcallosal approach with awake neuromonitoring. The results suggest it is possible to remove these tumors with reasonable outcomes ¹⁾.

From May 2011 to Aug 2015, 49 patients with thalamic gliomas underwent microsurgical resection, and received chemotherapy and radiotherapy postoperatively. The postoperative symptoms and complications were documented, and the overall survival (OS) and the progression-free survival (PFS) data were collected. The prognostic factors were evaluated by univariate and multivariate analyses. Finally, there was no perioperative death. Twenty cases, 24 cases and 5 cases were achieved subtotal resection (>90%), partial resection (70-90%) and less than partial resection (<70%) respectively. All patients’ pathological diagnosis was confirmed. The symptoms were improved in 32 cases, unchanged in 11 cases, and worsen in 6 cases. Postoperative complications were absent in 9 cases. The 6-month, 12-month, and 24-month OS were 71.4%, 38.9%, and 12.1% respectively; corresponding PFS were 66.6%, 27.1%, and 10.2% respectively. The median OS time and PFS time were 9.0 months (95% CI 6.9-11.1) and 9.0 months (95% CI 6.6-11.4) respectively. Multivariate analysis revealed extent of resection were independent prognostic factors for OS (p < .05), patients with postoperative adjuvant chemotherapy and radiotherapy had a significant prolonged OS (p < .001) and PFS (p < .001). The study shows that the short-term efficacy of microsurgery for high-grade thalamic gliomas is satisfactory. Microsurgery can effectively alleviate patients’ symptoms and improve life quality. Postoperative adjuvant chemotherapy and radiotherapy are helpful for prolonging the survival time ²⁾.

Series demonstrated the feasibility of the microsurgical concept. Comparison with other treatment modalities, such as brachytherapy, requires future consideration ³⁾.