Microsurgical approaches to the cerebellar interpeduncular region: qualitative and quantitative analysis

OBJECTIVE The cerebellar interpeduncular region (CIPR) is a gate for dorsolateral pontine and cerebellar lesions accessed through the supracerebellar infratentorial approach (SCITa), the occipital transtentorial approach (OTa), or the subtemporal transtentorial approach (STa). The authors sought to compare the exposures of the CIPR region that each of these approaches provided. METHODS Three approaches were performed bilaterally in eight silicone-injected cadaveric heads. The working area, area of exposure, depth of the surgical corridor, length of the interpeduncular sulcus (IPS) exposed, and bridging veins were statistically studied and compared based on each approach. RESULTS The OTa provided the largest working area (1421 mm2; p < 0.0001) and the longest surgical corridor (6.75 cm; p = 0.0006). Compared with the SCITa, the STa provided a larger exposure area (249.3 mm2; p = 0.0148) and exposed more of the length of the IPS (1.15 cm; p = 0.0484). The most bridging veins were encountered with the SCITa; however, no significant differences were found between this approach and the other approaches (p > 0.05). CONCLUSIONS To reach the CIPR, the STa provided a more extensive exposure area and more linear exposure than did the SCITa. The OTa offered a larger working area than the SCIT and the STa; however, the OTa had the most extensive surgical corridor. These data may help neurosurgeons select the most appropriate approach for lesions of the CIPR.

Paramedian Supracerebellar Infratentorial Approach for Pontine Cavernoma: 2-Dimensional Operative Video

We describe the case of a 26-yr-old male who presented with headaches, dizziness, and left hemi-hypoesthesia in addition to being COVID-19 positive. The patient was found to have a large hemorrhage in the right dorsolateral pons that was found to be due to a pontine cavernous malformation. The patient underwent a right-sided paramedian supracerebellar infratentorial approach for resection of this lesion with preservation of the developmental venous anomaly. We present the operative video with a specific focus on approach selection, anatomic illustrations, and technical nuances. The literature on the timing of brainstem cavernoma surgery is reviewed.1-4 The patient's postoperative clinical course and postoperative imaging are reviewed. The patient gave informed consent for the procedure and verbal consent for being part of this submission and the publication of their image.

Neuroendoscopic followed by microsurgical approach for the treatment of pilocytic astrocytoma of the pineal region

Pilocytic astrocytoma is a low-grade tumor that can affect the pineal region and has a potential life-threatening presentation with obstructive hydrocephalus. This video presents the case of a child who underwent an endoscopic third ventriculostomy with tumor biopsy and for whom a supracerebellar infratentorial approach was chosen after confirmation of the diagnosis of a pilocytic astrocytoma. Herein, we discuss the technical details of both procedures, such as the single burr hole in the neuroendoscopic approach, the ventricular landmarks and identification of the venous sinus through neuronavigation, the anatomical landmarks during the supracerebellar infratentorial approach, and the use of ultrasonographic aspiration.

Extreme lateral supracerebellar infratentorial approach for tentorial arteriovenous fistula associated with a giant venous ectasia: how I do it

Background Surgery of tentorial dural arteriovenous fistulas (DAVF) associated with large ectatic vein remains challenging due to the intimate neurovascular relationships in the incisural space. Interruption of the arterialized vein requires a good knowledge of the regional anatomy and a precise preoperative evaluation. Methods We describe the key steps extreme lateral supracerebellar infratentorial (ELSI) approach for tentorial DAVF with a video illustration. The surgical anatomy is described along with the advantages and limitations of this approach. Conclusions In cases of tentorial DAVF where the foot of the arterialized vein is located in the infratentorial compartment, ELSI offers good surgical exposure and outcomes.

Combined microsurgical-endoscopic paramedian supracerebellar-infratentorial approach for resection of a pineal low-grade glioma

The authors present the case of a 20-year-old male with a history of headaches and blurred vision found to have a pineal mass and chronic hydrocephalus. The patient initially underwent an endoscopic third ventriculostomy and pineal mass biopsy that revealed a low-grade neuroepithelial neoplasm. A microsurgery-endoscope–assisted paramedian supracerebellar-infratentorial approach was chosen and a gross-total resection was achieved. The patient’s postoperative and follow-up course has been unremarkable, with early postoperative imaging demonstrating no residual tumoral mass. The operative video highlights the advantages of endoscopic visualization for deep lesions in the pineal region and posterior third ventricle. The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2119.

Endoscopic supracerebellar infratentorial approach to pineal region epidermoid tumor

Epidermoid cysts of the pineal region are a rare entity. Herein, the authors describe the endoscopic resection of a recurrent pineal region epidermoid by way of a supracerebellar infratentorial approach. The patient was positioned in the semiseated upright position with head tilted to the right and slightly flexed, maximizing gravity-based cerebellar retraction, and a paramedian craniotomy was performed owing to the gradual flattening of the tentorium from medial to lateral. This setup, in tandem with the enlarged viewing window achieved by use of 0°, 30°, and 70° endoscopes, afforded the necessary access to achieve a satisfactory resection through this anatomical corridor. The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2131.

Resection of a pineal region papillary tumor using robotic exoscope: improved visualization and ergonomics for deep seeded tumor

Surgery for pineal region tumors is technically challenging due to their deep location and close proximity to critical deep venous structures, midbrain, and thalamus. A high-definition video exoscope was recently proposed as an alternative to the operating microscope. The authors illustrate a case of the midline supracerebellar infratentorial approach to resect a pineal region tumor using the Modus V exoscope and demonstrate the improved visualization of critical structures in this deep location. Additionally, the marked improvement in surgeon comfort suggests that this system may have significant advantages over traditional microscope-based surgery for tumors of the pineal region. The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2127.