The paramedian supracerebellar transtentorial approach to the posterior fusiform gyrus

Endoscopic-enhanced supra-cerebellar trans-tentorial (SCTT) approach to temporo-mesial region: a multicenter study

Surgical access to the temporo-mesial area may be achieved by several routes such as the sub-temporal, the temporal trans-ventricular, the pterional/trans-sylvian, and the occipital interhemispheric approaches; nonetheless, none of them has shown to be superior to the others. The supra-cerebellar trans-tentorial approach allows a great exposure of the middle and posterior temporo-mesial region, while avoiding temporal lobe retraction. A prospective multicenter study was designed to collect data on patients undergoing endoscopic-enhanced SCTT approach to excise left temporo-mesial lesions. The study involved 5 different neurosurgical European centers and ran from 2015 to 2020. All patients had preoperative as well as postoperative brain MRI and ophthalmology evaluation. A total of 30 patients were included in this study, the mean follow-up was 44 months (range 18 to 84 months), male/female ratio was 16/14, and mean age was 39 years. A gross total resection was achieved in 29/30 (96.7%) cases. All surgical procedures were uneventful, without transient or permanent neurological deficits thanks to the preservation of the posterior cerebral artery. The endoscopic-enhanced SCTT approach provides satisfactory exposure to the left temporo-mesial region. Its minimally invasive nature helps minimize the surgical risks related to vascular and white tract manipulation, which represent known limitations of open microsurgical as well as other approaches.

Supracerebellar transtentorial approach for left parahippocampal cavernous malformation

Background:

Lesions in the temporomesial region can be reached by various approaches: subtemporal, transsylvian, transcortical, interhemispheric parieto-occipital, or supracerebellar transtentorial (SCTT). The choice varies according to the characteristics of the lesion and neighboring structures.

Case Description:

In this clinical case, it is presented a 56-year-old man with long-term evolution of drug-resistant epilepsy secondary to a cavernoma in the left parahippocampal gyrus. After assessing the lesion, it was decided a SCTT approach for its resection in a semi-sitting position, to avoid language disorders or visual damage. The surgery was uneventful and the patient did not present epileptic seizures during 6-month follow-up.

Conclusion:

Performing a SCTT is safe and feasible option for resection of lesions located in the basal temporomesial region without causing damage to neighboring structures, especially those located in the middle and posterior two-thirds of temporal region.

How I do it: paramedian supracerebellar transtentorial approach for a temporomesial glioma

BACKGROUND

Classical approaches to the temporomesial region (TMR) include transtemporal, transylvian, or subtemporal. The supracerebellar infratentorial, initially developed to access dorsolateral cavernomas, has of late shown its versatility to access areas around the central core. The TMR is one such area that can be accessed through this approach with the addition of a tentorial incision.

METHOD

The paramedian supracerebellar transtentorial approach (PSCTA) is described along with its advantages and limits compared to other approaches to treat TMR gliomas.

CONCLUSION

The PSCTA offers a basal panoramic view of the TMR without the need of retraction, cortical incision, and white matter transgression.

Endoscope-Assisted Neuroportal Transcerebellar Approach to the Fourth Ventricle: An Anatomical Study

BACKGROUND AND STUDY AIMS

 Minimally invasive approaches to deep-seated lesions still represent a fundamental issue in modern neurosurgery. Tubular retractors allow to enhance the operability of intraventricular lesions, minimizing the risk of damages to brain parenchyma. Increasing interest for portal devices has been mainly focused on supratentorial pathologies, while transportal approaches in the posterior cranial fossa have been rarely described. In the present study, the authors aimed to investigate the surgical exposure and operability obtained with a microsurgical neuroportal transcerebellar approach targeting the fourth ventricle, assisted by endoscopic exploration.

MATERIAL AND METHODS

 Six cadaveric specimens were provided for anatomical microsurgical dissection and Vycor ViewSite Brain Access System was used as tubular retractor. Surgical feasibility of the neuroportal transcerebellar approach was demonstrated through a definable and measurable parameter, the operability score.

RESULTS

 The neuroport provided a surgical corridor away from eloquent structures to target the whole fourth ventricle cavity, preventing injury to cerebellar nuclei and white matter pathways and, potentially, minimizing the risk of surgical morbidity. Maximal operability was reached in the pontomedullary junction and medullary area of the ventricular floor. Transportal endoscopic assistance contributed to a further extension of surgical exposure in blind spots, corresponding to the ipsilateral lateral recess, the uppermost part of the fourth ventricle, and the obex.

CONCLUSION

 The neuroportal transcerebellar approach represents a viable alternative route to the fourth ventricle, avoiding vermian splitting or subarachnoid dissection of the cerebellomedullary cistern. Endoscopic assistance enhances the exposure of the surgical field and accomplishes a valid instrument for intraventricular orientation to ease microsurgical procedures.

Extreme Lateral Supracerebellar Infratentorial Approach: Surgical Anatomy and Review of the Literature

OBJECTIVE

The extreme lateral supracerebellar infratentorial (ELSI) approach has the potential to access several distinct anatomical regions that are otherwise difficult to reach. We have illustrated the surgical anatomy through cadaveric dissections and provided an extensive review of the literature to highlight the versatility of this approach, its limits, and comparisons with alternative approaches.

METHODS

The surgical anatomy of the ELSI has been described using 1 adult-injected cadaveric head. Formalized noninjected brain specimens were also dissected to describe the brain parenchymal anatomy of the region. An extensive review of the literature was performed according to each targeted anatomical region. Illustrative cases are also presented.

RESULTS

The ELSI approach allows for wide exposure of the middle and posterolateral incisural spaces with direct access to centrally located intra-axial structures such as the splenium, pulvinar, brainstem, and mesial temporal lobe. In addition, for skull base extra-axial tumors such as petroclival meningiomas, the ELSI approach represents a rapid and adequate method of access without the use of extensive skull base approaches.

CONCLUSIONS

The ELSI approach represents one of the most versatile approaches with respect to its ability to address several anatomical regions centered at the posterior and middle incisural spaces. For intra-axial pathologies, the approach allows for access to the central core of the brain with several advantages compared with alternate approaches that frequently involve significant brain retraction and cortical incisions. In specific cases of skull base lesions, the ELSI approach is an elegant alternative to traditionally used skull base approaches, thereby avoiding approach-related morbidity.

Transcorticosubcortical Approach for Left Posterior Mediobasal Temporal Region Gliomas: A Case Series and Anatomic Review of Relevant White Matter Tracts

BACKGROUND AND OBJECTIVE

The goal of this study is to show using 5 illustrative cases that the transcortical route for resection of mediobasal temporal region (MBTR) lesions is safe and effective when performed with awake functional mapping and knowledge of the relevant subcortical anatomy. Although several have been proposed, there is a paucity of reports on transcorticosubcortical approaches to these lesions, particularly in patients with posterior-superior extension. We present a case series of 5 patients with left posterior MBTR gliomas and summarize the relevant subcortical anatomy knowledge of what is a prerequisite for safe resection.

METHODS

Five patients with left posterior MBTR gliomas underwent awake resection with functional corticosubcortical electric mapping. Details of the approach are presented with a review of relevant anatomy.

RESULTS

Gross total resection was achieved in 4 patients. One patient who had previously undergone radiation therapy had a subtotal resection. There were 4 cases of World Health Organization grade II glioma and 1 case of World Health Organization grade IV glioma. All patients underwent preoperative and postoperative neurologic and neuropsychological assessment and there were no new or worsening sensorimotor, visual, language, or cognitive deficits.

CONCLUSIONS

The transcorticosubcortical approach is a safe and effective approach to lesions of the posterior MBTR. The approach is safe and effective even in patients with superior extension, if the surgical approach is predicated on knowledge of individual functional anatomy. Awake resection with cortical and axonal mapping with well-selected paradigms is invaluable in maximizing extent of resection and ensuring patient safety.