Surgical Approaches to the Thalamus in Relation to the White Matter Tracts of the Cerebrum

Endoscopic Supracerebellar Infratentorial Transpineal Approach for Posterior-Medial Thalamic Lesions: Surgical Technique and Clinical Experience

BACKGROUND AND OBJECTIVES

Accessing lesions in the posterior-medial thalamus can be challenging because of their deep location and intricate neurovascular anatomy. This study aims to describe the techniques and feasibility of the endoscopic supracerebellar infratentorial transpineal approach for treating posterior-medial thalamus lesions.

METHODS

We reviewed and analyzed the clinical outcomes and endoscopic surgical experience of 11 patients with posterior-medial thalamic lesions. The first 4 cases used the endoscopic midline supracerebellar infratentorial transpineal approach, whereas the subsequent 7 cases used the endoscopic contralateral paramedian supracerebellar infratentorial transpineal approach. All cases involved the upward transposition of the pineal gland to access the posterior-medial thalamus. The extent of resection and the endoscopic techniques were the main focus of analysis. Neurological examinations and MRI/computed tomography follow-up were conducted for 3-12 months after surgery.

RESULTS

The pathology of the group included 6 gliomas, 1 cavernous malformation, 1 inflammation, 1 melanoma, and 2 hematomas. All 11 patients achieved gross total resection (6 patients, 54.5%) or subtotal resection (5 patients, 45.5%) with no new neurological deficits. Most patients (9 patients, 81.8%) experienced improvement in Karnofsky Performance Status after surgery. Postoperative hydrocephalus occurred in 2 patients (18.2%) and was relieved by endoscopic third ventriculostomy.

CONCLUSION

The endoscopic supracerebellar infratentorial transpineal approach is an effective approach for removing posterior-medial thalamic lesions that require access through the third ventricle surfaces of the thalamus. The endoscopic contralateral paramedian supracerebellar infratentorial transpineal approach provides a more superior and lateral view of the posterior-medial thalamic lesions.

An endoscopic-assisted contralateral paramedian supracerebellar infratentorial approach in the treatment of thalamic hemorrhage with hematoma extension into the brainstem: a case report

Objective

Thalamic hemorrhage (TH) with hematoma extension into the brainstem can lead to poor outcomes. In this study, we discuss the feasibility of the endoscopic-assisted contralateral paramedian supracerebellar infratentorial (SCIT) approach as a therapeutic method for treating such patients.

Case presentation

A patient suffered from a sudden loss of consciousness and right limb weakness, and a CT scan indicated TH with hematoma extension into the brainstem. She consented to undergo surgery by the endoscopic-assisted contralateral paramedian SCIT approach.

Results

Now, the patient can open her eyes on her own and move her left arm in response to commands.

Conclusion

The endoscopic-assisted contralateral paramedian SCIT approach may be a viable therapeutic method for treating TH patients with hematoma extension into the brainstem.

Dynamic Lateral Semisitting Position for Supracerebellar Approaches: Technical Note and Case Series

BACKGROUND

It has always been a matter of debate which position is ideal for the supracerebellar approach. The risk of venous air embolism (VAE) is the major deterrent for surgeons and anesthesiologists, despite the fact that sitting and semisitting positions are commonly used in these operations.

OBJECTIVE

To demonstrate a reduction on the risk of VAE and tension pneumocephalus throughout the operation period while taking advantages of the semisitting position.

METHODS

In this study, 11 patients with various diagnoses were operated in our department using the supracerebellar approach in the dynamic lateral semisitting position. We used end-tidal carbon dioxide and arterial blood pressure monitoring to detect venous air embolism.

RESULTS

None of the patients had clinically significant VAE in this study. No tension pneumocephalus or major complications were observed. All the patients were extubated safely after surgery.

CONCLUSION

The ideal position, with which to apply the supracerebellar approach, is still a challenge. In our study, we presented an alternative position that has advantages of the sitting and semisitting positions with a lower risk of venous air embolism.

Neuronavigation-Guided Transcortical-Transventricular Endoport-Assisted Endoscopic Resection for Thalamic Lesions: Preliminary Experience

BACKGROUND

Surgery for thalamic lesions is generally challenging because they are deep-seated lesions surrounded by vital neurovascular structures. Whether neuronavigation-guided transcortical-transventricular endoport-assisted endoscopic resection for thalamic lesions is feasible remains to be further evaluated.

METHODS

A retrospective review of 8 who patients received neuronavigation-guided transcortical-transventricular endoport-assisted endoscopic resection for thalamic lesions was performed. Preoperative and tumor-related variables and postoperative outcomes were analyzed.

RESULTS

All lesions were located in the medial part of the thalamus, and most of them expanded forward, downward, or backward. Median size of lesions was 31 mm (range, 16-52 mm). Final pathology results confirmed that 1 case was a cavernous malformation, 3 were pilocytic astrocytomas, and 4 were glioblastomas. None of the patients had postoperative seizures. Gross total resection and long-term postoperative survival were achieved in all patients with benign lesions, while near-total resection (>90%) was achieved in 3 of 4 patients (75%) with glioblastoma, and subtotal resection (<90%) was achieved in 1 patient (25%). Among patients with glioblastoma, 1 patient remained free of recurrence at 16 months of follow-up; the other 3 patients had worse Karnofsky performance scale scores after surgery and died within 6 months.

CONCLUSIONS

Combining the advantages of neuronavigation, endoscopy, and endoport techniques via the middle frontal gyrus approach can safely and effectively remove benign lesions in the medial part of the thalamus. This procedure can also be performed in well-selected cases of glioblastoma and likely confers a survival advantage for this rapidly and universally fatal disease.

Surgical Approach to Thalamic Tumors

Thalamic tumors are deep-seated lesions. Recent improvements in therapeutic approaches and surgical techniques have allowed a more accurate approach to these lesions and a reduction in morbidity and mortality. In this article, the various surgical approaches for the resection of thalamic tumors are described. Each of these approaches has its own indications and risk of complications. Resection of thalamic tumors needs specific anatomical knowledge, especially the vascular anatomy of the region and the thalamic peduncles.

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.

Assessing the connectional anatomy of superior and lateral surgical approaches for medial temporal lobe epilepsy

The most common approaches in the treatment of epilepsy, the trans-sylvian selective amygdalohippocampectomy (SAH) and the anterior temporal lobe resection (ATLR) reach the medial temporal lobe through different surgical routes. Our aim was to delineate the white matter (WM) fiber tracts at risk in relation to trans-sylvian SAH and ATLR by defining each fascicle en route to medial temporal lobe during each approach. ATLR and trans-sylvian SAH were performedand related WM tracts en route to medial temporal region were presented in relation to the relevant approaches and surrounding neurovascular structures. The WM tracts most likely to be disrupted during trans-sylvian SAH along the roof of the temporal horn were the UF - and less commonly IFOF - at the layer of the external capsule, anterior commissure, anterior bend of optic radiations, and sublenticular internal capsule. Amygdaloid projections to the claustrum, putamen and globus pallidus, the tail of caudate and the peduncle of the lentiform nucleus were also in close proximity to the resection cavity. Fiber tracts most likely to be impaired during ATLR included the UF, ILF, IFOF, anterior commissure, optic radiations, and, less likely, the vertical ventral segment of the arcuate fascicle. Both ATLR and trans-sylvian SAH carry the risk of injury to WM pathways, which may result in unpredictable functional loss. A detailed 3-D knowledge of the related connectional anatomy will help subside neurocognitive, neuroophtalmologic, neurolinguistic complications of epilepsy surgery, providing an opportunity to tailor the surgery according to patient's unique connectional and functional anatomy.

White matter dissection with the Klingler technique: a literature review

The aim of this literature review is to present a summary of the published literature relating the details of the different modifications of specimen preparation for white matter dissection with the Klingler technique. For this review, 3 independent investigators performed an electronic literature search that was carried out in the Pubmed, Scopus and Web of Science databses up to December 2019. Furthermore, we performed citation tracking for the articles missed in the initial search. Studies were eligible for inclusion when they reported details of at least the first 2 main steps of Klingler's technique: fixation and freezing. A total of 37 full-text articles were included in the analysis. We included original anatomical studies in which human white matter dissection was performed for study purposes. The main three steps of preparation are the same in each laboratory, but the details of each vary between studies. Ten percent formalin is the most commonly used (34 studies) solution for fixation. The freezing time varied between 8 h and a month, and the temperature varied from - 5 to - 80 °C. After thawing and during dissections, the specimens were most often kept in formalin solution (13), and the concentration varied from 4 to 10%. Klingler's preparation technique involves three main steps: fixation, freezing and thawing. Even though the details of the technique are different in most of the studies, all provide subjectively good quality specimens for anatomical dissections and studies.