Paramedian Supracerebellar Infratentorial Approach Research Articles

A taxonomy for deep cerebral cavernous malformations: subtypes of thalamic lesions.

Anatomical taxonomy is a practical tool to successfully guide clinical decision-making for patients with brain arteriovenous malformations and brainstem cavernous malformations (CMs). Deep cerebral CMs are complex, difficult to access, and highly variable in size, shape, and position. The authors propose a novel taxonomic system for deep CMs in the thalamus based on clinical presentation (syndromes) and anatomical location (identified on MRI). The taxonomic system was developed and applied to an extensive 2-surgeon experience from 2001 through 2019. Deep CMs involving the thalamus were identified. These CMs were subtyped on the basis of the predominant surface presentation identified on preoperative MRI. Six subtypes among 75 thalamic CMs were defined: anterior (7/75, 9%), medial (22/75, 29%), lateral (10/75, 13%), choroidal (9/75, 12%), pulvinar (19/75, 25%), and geniculate (8/75, 11%). Neurological outcomes were assessed using modified Rankin Scale (mRS) scores. A postoperative score ≤ 2 was defined as a favorable outcome and > 2 as a poor outcome. Clinical and surgical characteristics and neurological outcomes were compared among subtypes. Seventy-five patients underwent resection of thalamic CMs and had clinical and radiological data available. Their mean age was 40.9 (SD 15.2) years. Each thalamic CM subtype was associated with a recognizable constellation of neurological symptoms. The common symptoms were severe or worsening headaches (30/75, 40%), hemiparesis (27/75, 36%), hemianesthesia (21/75, 28%), blurred vision (14/75, 19%), and hydrocephalus (9/75, 12%). The thalamic CM subtype determined the selection of surgical approach. A single approach was associated with each subtype for most patients. The main exception to this paradigm was that in the surgeons' early experience, pulvinar CMs were resected through a superior parietal lobule-transatrial approach (4/19, 21%), which later evolved to the paramedian supracerebellar-infratentorial approach (12/19, 63%). Relative outcomes implied by mRS scores were unchanged or improved in most patients (61/66, 92%) postoperatively. This study confirms the authors' hypothesis that this taxonomy for thalamic CMs can meaningfully guide the selection of surgical approach and resection strategy. The proposed taxonomy can increase diagnostic acumen at the patient bedside, help identify optimal surgical approaches, enhance the clarity of clinical communications and publications, and improve patient outcomes.

Paramedian Supracerebellar Infratentorial Approach for Clipping a Ruptured Aneurysm in the Cerebellomesencephalic Segment of the Left Superior Cerebellar Artery: A Case Report

Superior cerebellar artery (SCA) aneurysms are rare, especially for those arising from the distal portion of the SCA. In this study, we presented a case of a ruptured aneurysm arising from cerebellomesencephalic segment of the SCA. A woman with severe headache and neck stiffness had a ruptured aneurysm arising from cerebellomesencephalic segment of the left SCA. Treated successfully with left-sided paramedian supracerebellar infratentorial (SCIT) approach for clipping the aneurysm with a sitting position, discharged after 14 days without neurological deficit. SCA aneurysms can be managed by endovascular coiling or microsurgical clipping. Although both modalities pose risks of damaging the brainstem perforators, the incidence of the SCIT approach is low since it is exposure from laterally to medially and from distal to proximal along the course of SCA. In our viewpoint, the paramedian SCIT approach is a safe and effective treatment for clipping aneurysms arising from the distal portion of the SCA.

Endoscopically assisted presigmoid retrolabyrinthine approach to the lateral mesencephalic sulcus: a cadaveric study with comparison to the variant supracerebellar infratentorial approaches.

The supracerebellar infratentorial (SCIT) approach is commonly used to gain access to the lateral mesencephalic sulcus (LMS), which has been established as a safe entry point into the posterolateral midbrain. This study describes a lateral variant of the SCIT approach, the supreme-lateral SCIT approach, for accessing the LMS through the presigmoid retrolabyrinthine craniectomy and quantitatively compares this approach with the paramedian and extreme-lateral SCIT approaches. Anatomical dissections were performed in four cadaveric heads. In each head, the supreme-lateral SCIT approach was established on one side, following a detailed description of each step, whereas the paramedian and supreme-lateral SCIT approaches were established on the other side. Quantitative measurements of the exposed posterolateral midbrain, the angles of LMS entry, and the depth of surgical corridors were recorded and compared between the three SCIT approach variants. The supreme-lateral (67.70 ± 23.14 mm2) and extreme-lateral (70.83 ± 24.99 mm2) SCIT approaches resulted in larger areas of exposure anterior to the LMS than the paramedian SCIT approach (38.61 ± 9.84 mm2); the supreme-lateral SCIT approach resulted in a significantly smaller area of exposure posterior to the LMS (65.24 ± 6.81 mm2) than the other two variants (paramedian = 162.75 ± 31.98 mm2; extreme-lateral = 143.10 ± 23.26mm2; both P < .001). Moreover, the supreme-lateral SCIT approach resulted in a surgical corridor with a shallower depth and a smaller angle relative to the horizontal plane than the other two variants. The supreme-lateral SCIT approach is a more lateral approach than the extreme-lateral SCIT approach, providing a subtemporal approach with direct LMS visualization. The supreme-lateral SCIT offers the benefits of both subtemporal and SCIT approaches and represents a suitable option for the management of selected midbrain pathologies.

Endoscopic resection of thalamic lesions via supracerebellar infratentorial approach: a case series and technical note.

The deep location of the thalamus and the complex neural circuits in the surrounding area make surgery extremely challenging. Feasibility and advisability of using a supracerebellar infratentorial approach (SCITA) for endoscopic resection of thalamic lesions remains to be further evaluated. Fifteen patients who underwent endoscopic resection of thalamic via SCITA from 2014 to 2021 were retrospectively collected. We analyzed preoperative tumor-related variables and surgical procedures in detail, as well as postoperative outcomes. Lesions mainly located in the posterior and/or medial part of the thalamus, and some of them expanded downward, or backward. The mean size of them was 30 × 24mm. Five of the nine patients with preoperative hydrocephalus underwent cerebrospinal fluid shunts to relieve increased intracranial pressure. Among the 15 patients, 4 were glioblastoma, 3 were pilocytic astrocytoma, and the rest included 1 case of anaplastic astrocytoma, melanoma, polymorphous low-grade neuroepithelial tumor of the young, rosette-forming glioneuronal tumor, inflammatory lesion, diffuse midline glioma, and cavernous hemangioma. The majority of patients (10/15) achieved gross total resection, which has become more pronounced since paramedian SCITA was used in place of the midline approach in 2020 (6/8). Three patients had unresolved or new onset of clinical symptoms after surgery, resulting in a decreased KPS score at discharge. Neuro-endoscopic techniques can ameliorate many of the shortcomings of the SCITA. With the accumulation of experience and technological progress, more deficiencies of this approach may be improved, enabling safe and effective resection of posterior and/or medial part thalamic lesions.

Endoscopic-assisted paramedian supracerebellar infratentorial approach to the posterior portion of the third ventricle. Anatomical study and surgical cases.

To date, morphometrical data providing a systematic quantification of accessibility and operability parameters to the boundaries of the posterior portion of the third ventricle (PTV) when applying an endoscopic-assisted paramedian supracerebellar infratentorial approach (EPSIA) are lacking. We performed an anatomical study and complemented our findings with surgical cases. Eight EPSIAs towards the PTV were performed in cadaveric specimens. Optimal approach angles (OA), surgical freedom (SF) and operability indexes (Oi) to the PTV boundaries were assessed. Additionally, a 54-year-old man and 33-year-old woman were operated on PTV tumors applying the EPSIA. Sagittal OA to ventricle's roof and floor was 36±1.4° and 25.5±3.5° respectively, axial OA to the ipsilateral and contralateral ventricle's wall were 9.5±1.3° and 28.5±1.6°. SF was maximal on the contralateral wall (121.2±19.3mm2), followed by the roof (112.7±18.8mm2), floor (106.6±19.2mm2) and ipsilateral wall (94.1±15.7mm2). SF was significantly lower along the ipsilateral compared the contralateral wall (p<0.01) and roof (p<0.05). Facilitated surgical maneuvers with multiangled exposure were possible up to 8.5±1.07mm anterior to ventricle's entrance, whereas surgical maneuvers were possible but difficult up to 15.25±3.7mm. Visualization of more anterior was possible up to a distance of 27±2.9mm, but surgical maneuvers were barely feasible. EPSIA enabled successful resection of both PTV tumors and postoperative course was uneventful. EPSIA can be effective for approaching the PTV, enabling surgery along all boundaries, but especially on its roof and contralateral wall. In the not-enlarged ventricle, surgical maneuvers are feasible up to the level of the Monro foramen, becoming more limited anteriorly.

Two-stage endoscopic assisted approach for large pineal region and falcotentorial meningioma: first stage paramedian supracerebellar infratentorial approach, second stage interhemispheric occipital transtentorial approach: surgical cases and anatomical study.

Resection of complex falcotentorial meningiomas, growing along the pineal region (PR), and posterior incisural space (PIS) represents a neurosurgical challenge. Here, we present our strategy for effective resection of large falcotentorial meningiomas applying a paramedian supracerebellar infratentorial and interhemispheric occipital transtentorial approach in staged surgeries. We further systematically compared the effectiveness of midline (MSIA) and paramedian (PSIA) supracerebellar infratentorial, as well as interhemispheric occipital transtentorial approaches (IOTA) to operate along the PR and PIS in 8 cadaveric specimens. The staged PSIA and IOTA enabled successful resection of both falcotentorial meningiomas with an uneventful postoperative course. In our anatomo-morphometrical study, superficial vermian veins at an average depth of 11.38 ± 1.5mm and the superior vermian vein (SVV) at 54.13 ± 4.12mm limited the access to the PIS during MSIA. MSIA required sacrifice of these veins and retraction of the vermian culmen of 20.88 ± 2.03mm to obtain comparable operability indexes to PSIA and IOTA. Cerebellar and occipital lobe retraction averaged 14.31 ± 1.014mm and 14.81 ± 1.17mm during PSIA and IOTA respectively, which was significantly lower than during MSIA (p < 0.001). Only few minuscule veins were encountered along the access through PSIA and IOTA. The application of PSIA provided high operability scores around the pineal gland, ipsilateral colliculus and splenium, and acceptable scores on contralateral structures. The main advantage of IOTA was improving surgical maneuvers along the ipsilateral splenium. In summary, IOTA and PSIA may be advantageous in terms of brain retraction, vein sacrifice, and operability along the PR and PIS and can be effective for resection of complex falcotentorial meningiomas.

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.

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.

Commentary: Virtual Reality Surgical Rehearsal and 2-Dimensional Operative Video of a Paramedian Supracerebellar Infratentorial Approach Endoscopic Resection of Pineocytoma: 2-Dimensional Operative Video.

Commentary: Virtual Reality Surgical Rehearsal and 2-Dimensional Operative Video of a Paramedian Supracerebellar Infratentorial Approach Endoscopic Resection of Pineocytoma: 2-Dimensional Operative Video.

Commentary: Virtual Reality Surgical Rehearsal and 2-Dimensional Operative Video of a Paramedian Supracerebellar Infratentorial Approach Endoscopic Resection of Pineocytoma: 2-Dimensional Operative Video.

Commentary: Virtual Reality Surgical Rehearsal and 2-Dimensional Operative Video of a Paramedian Supracerebellar Infratentorial Approach Endoscopic Resection of Pineocytoma: 2-Dimensional Operative Video.

Endoscopic-assisted microsurgical paramedian supracerebellar infratentorial approach to the posterior third ventricle. An anatomical morphometrical study and technical note with illustrative surgical cases

Endoscopic-assisted microsurgical paramedian supracerebellar infratentorial approach to the posterior third ventricle. An anatomical morphometrical study and technical note with illustrative surgical cases

Functional status of surgically treated pineal cyst patients.

Background: Microsurgical removal represents a well-accepted treatment option for symptomatic benign pineal cysts (PCs). However, very few studies have quantitatively evaluated the functional status of surgically treated PC patients.Methods: A detailed analysis of preoperative, immediate postoperative, and long-term clinical and radiological characteristics was performed. The functional status of the patients was categorized using the modified Rankin scale (mRS) and the Chicago Chiari Outcome Scale (CCOS). In addition, a comparative analysis between pediatric and adult patients with PCs was carried out.Results: Overall, pediatric patients experienced better long-term mRS scores than adults. The differences between the pre-, the immediate post-, and the last postoperative mRS of the patients were statistically significant for the total population (P < 0.001). All patients obtained a CCOS of 11 or more, which reflects a good/optimal result after microneurosurgery. The type of the surgical approach was independently associated with the postoperative complications (P < 0.01), more frequently reported with the midline supracerebellar infratentorial (SCIT) approach than with its paramedian modification.Conclusion: The functional status of properly selected symptomatic patients with PCs may improve significantly after their surgical management through a paramedian SCIT approach in sitting position.

Midline and Paramedian Supracerebellar Infratentorial Approach to The Pineal Region: A Comparative Clinical Study in 112 Patients

The midline supracerebellar infratentorial (SCIT) approach and its paramedian development are commonly used for dealing with pineal lesions. Comparative clinical studies are lacking, however. We aim to establish the better performance of the paramedian SCIT approach in terms of clinical safety in surgically treated pineal cysts and pineal region tumors. Procedural functionality and effectiveness have been also analyzed. A comparative analysis of clinical, radiologic, pathologic, and surgical features, and outcome was performed between 55 midline and 57 paramedian SCIT approaches that were exclusively performed in 112 patients (57 pineal cysts and 55 tumors of the pineal region) operated in sitting position by a single surgeon. Information was retrieved from hospital records and microsurgical videos. The paramedian SCIT approach linked with fewer postoperative complications (odds ratio [OR]: 0.40) and fewer approach-related complications (OR: 0.28) than the midline SCIT approach. The SCIT paramedian approach was achieved in a shorter time, by a smaller bone flap, and with fewer complex procedural steps than the midline approach. The SCIT paramedian approach did not require the opening of the falx cerebelli, midline cerebellar retraction, section of the midline cerebellar draining veins, nor wide opening of the dura. Gross total resection, size of the lesion, microsurgical time for removal, histopathological diagnosis and postoperative outcome were statistically similar in both groups. The SCIT approach represents a safer and more functional approach for the removal of cysts and tumors of the pineal region than the classic midline approach, while maintaining the same effectiveness.

Unedited microneurosurgery of a posterior fossa pilocytic astrocytoma.

Background:Pilocytic astrocytoma (PA) is a WHO grade I glioma and the most common pediatric brain tumor. PA is most commonly localized in the cerebellum with extremely rare disemination and progression to higher grade astrocytomas. Thus, overall survival rates are excellent after gross total resection. Herein, we present an unedited microneurosurgery of a histologically confirmed cerebellar PA. Our aim is to demonstrate the efficiency and safety of our microsurgical technique into deep brain territories. For this, a paramedian supracerebellar infratentorial approach and a proper praying sitting position are essential.Case Description:A patient with cerebellar PA was placed in a sitting praying position to perform a right paramedian supracerebellar infratentorial approach. The lesion was identified after opening the superior cerebellar surface, followed by tissue samples and partial debulking under high microscopic magnification. Internal debulking of the tumor was performed with ring microforceps and bipolar forceps in the right hand and a thumb-regulated suction tube in the left hand. The poorly differentiated borders between the tumor and the surrounding parenchyma were determined under microscopic vision. Bipolar coagulation forceps were used to shrink the tumor and to remove it by piecemeal reduction. Small vessels feeding the tumor were coagulated and cut. Water irrigation provided us a clean surgical field and the recognition of small bleeding vessels. The final steps included evaluation of some hidden tumor remnants and meticulous hemostasis with electrocoagulation. After gross total removal of the tumor, the large cerebellar surface was covered by Tachosil and Surgicel. In our experience, both elements are essential for a good hemostasis. The postoperative course was uneventful and the patient is alive and free of tumor recurrence.Conclusion:This unedited video offers all detailed aspects that are, as the senior author JH considers, essential for a neurosurgeon when performing an efficient and safe surgery for a large PA in the posterior fossa.Videolink: http://surgicalneurologyint.com/videogallery/cerebellar-tumor

Unedited microneurosurgery of a solitary fibrous tumor of the pineal region.

Background:Solitary fibrous tumor/hemangiopericytoma is a new combined entity introduced in the 2016 World Health Organization classification of tumors of the central nervous system for grade I–III soft-tissue tumors. While grades II and III present more aggressive course and might require adjuvant radiochemotherapy, grade I tumors have a good outcome after gross total resection. In this video-abstract, we present an unedited microneurosurgery of a histologically confirmed benign solitary fibrous tumor of the pineal region performed by a senior author (JH). Our aim is to demonstrate the efficiency and safety of our microsurgical technique into deep brain territories under the principle “simple, clean, and preserving the normal anatomy.” For this, a paramedian supracerebellar infratentorial approach and a proper praying sitting position are essential.Case Description:A patient with a history of slow progressive hydrocephalus was placed in a sitting praying position. The pineal region was accessed over the right cerebellar hemisphere following a right paramedian supracerebellar infratentorial approach. The lesion identified after a lateral opening of the quadrigeminal cistern followed partial debulking. Small vessels running on the surface of the tumor were coagulated and cut. After a careful dissection and devascularization of the lesion, the tumor was pulled out using long ring microforceps and long sharp bipolar forceps as well. The final steps included detachment of some tumoral remnants from the internal cerebral veins and meticulous attention to any bleeding securing complete hemostasis of the surgical site. The postoperative course was uneventful with only slight and occasionally double vision. The patient is alive and free of recurrence almost 4 years after surgery.Conclusion:This unedited video offers all detailed aspects that a neurosurgeon like senior author JH considers essential when performing an efficient and safe surgery into the pineal region for this very rarely documented solitary fibrous tumor.Videolink:http://surgicalneurologyint.com/videogallery/pineal-tumor

Unedited microneurosurgery of a high-grade pineal parenchymal tumor of intermediate differentiation.

Background:WHO Grade II–III pineal parenchymal tumors of intermediate differentiation (PPTIDs) were included in the 2007 World Health Organization Classification of Central Nervous System Tumors as pineal parenchymal tumors between pineocytomas and pineoblastomas. PPTIDs comprise more than 20–60% of all pineal parenchymal tumors (PPT) s and are characterized by moderately high cellularity, mild-to-moderate nuclear atypia, and low-to-moderate mitotic activity. Moreover, PPTID includes transitional cases in which pineocytomatous and pineoblastoma features are associated. Synaptophysin and neuron-specific enolase are usually positive, with variable reactivity to neurofilament protein, chromogranin A, retinal S-antigen, and S-100 protein. PPTID Grades II and III can be distinguished on the basis of mitotic activity (higher in high-grade PPTID) and neurofilament protein immunoreactivity (higher in low-grade PPTID). Herein, we present the microsurgical management of a histologically confirmed high-grade PPTID.Case Description:A patient with high grade PPTID underwent sitting praying position and right paramedian supracerebellar infratentorial approach. The lesion was identified after lateral opening of the quadrigeminal cistern, followed by removal of its cystic component. Tissue samples were obtained under high microscopic magnification, and internal debulking of the tumor was performed with ring microforceps and bipolar forceps in the right hand and a thumb-regulated suction tube in the left hand. Continuous water irrigation provided us a clean surgical field and the recognition of small bleeding vessels. Moreover, water dissection technique was applied to recognize the cleavage plane of the tumor. Bipolar coagulation forceps were used to shrink the tumor and remove it by piecemeal reduction aiming to identify the anterior and lateral limits of the lesion. The poorly differentiated borders between the tumor and the surrounding parenchyma were determined under microscopic vision. Small vessels feeding the tumor were coagulated and cut. The most critical surgical stage was related with removal of some tumor remnants attached to the internal cerebral veins. A meticulous and skillful dissection was essential aiming to preserve these vascular structures. The final steps included meticulous hemostasis with electrocoagulation, Tachosil, and Surgicel. The postoperative course was uneventful. The patient underwent adjuvant radiotherapy and currently is alive, free of tumor recurrence 4 years after surgery.Conclusion:This unedited video offers all detailed aspects that are, as the senior author JH considers, essential for a neurosurgeon when performing an efficient and safe surgery for a high-grade PPTID.Videolink:http://surgicalneurologyint.com/videogallery/pineal-tumor-2