Supracerebellar Infratentorial Research Articles

Supracerebellar Infratentorial Approach to Cavernous Malformations of the Brainstem

The supracerebellar infratentorial (SCIT) approach can be performed at the midline (median variant), lateral to the midline (paramedian variant), or at the level of the angle formed by the transverse and sigmoid sinuses (extreme lateral variant). We analyzed our experience with SCIT approaches for the surgical treatment of cavernous malformations of the brainstem (CMBs). Demographic, clinical, radiologic, and surgical data from 45 patients (20 males and 25 females; mean age, 36.2 years) with CMBs surgically removed through SCIT approaches were reviewed retrospectively. Anatomic information was explored using cadaver head dissection. Twenty-three lesions were in the midbrain, 3 were at the midbrain and extended to the thalamus, 9 were at the pontomesencephalic junction, and 10 were in the upper pons. All patients presented with hemorrhage. The median variant was used in 13 patients, the paramedian variant in 9, and the extreme lateral variant in 23. Intraoperatively, all CMBs were associated with a developmental venous anomaly. At last follow-up, 88% of the patients were the same or better. After a mean follow-up of 20 months, their mean Glasgow Outcome Scale score was 4.1. SCIT approaches provide excellent exposure to CMBs located at the posterior incisural space, not only in the midline but also in the posterolateral surface of the upper pons and midbrain. Careful preoperative planning and neuronavigational assistance are needed to determine the best angle of attack and trajectory for SCIT approaches. Refined microsurgical techniques are paramount to achieve safe surgical removal of CMBs with good outcomes.

Supracerebellar Infratentorial Approach to Cavernous Malformations of the Brainstem: Surgical Variants and Clinical Experience With 45 Patients

Supracerebellar Infratentorial Approach to Cavernous Malformations of the Brainstem: Surgical Variants and Clinical Experience With 45 Patients

Far lateral supracerebellar infratentorial approach for the treatment of upper brainstem gliomas: clinical experience with pediatric patients

Surgical exposure of intrinsic lesions located lateral to the brainstem still represents a challenging task. The aim of this study was to assess the feasibility of the extracerebral far lateral supracerebellar infratentorial (FLSI) approach for the treatment of gliomas located in the upper brainstem in the pediatric population. Between 1992 and 2002, seven patients (mean age 8.7 years) with tumors of glial origin (WHO I-IV) located mainly in the pontomesencephalic region were operated with the FLSI approach in a sitting position. Satisfactory extent of resection without additional morbidity was achieved. In a carefully selected pediatric patient population, the FLSI approach proved to be a feasible and effective surgical route for the treatment of upper brainstem gliomas.

Surgery for Third Ventricular Tumors

A broad array of tumors of the central nervous system may arise within the third ventricular region, including gliomas; subependymal giant cell astrocytomas; meningiomas; pineal region tumors; and cysts, including ependymal, arachnoid, epidermoid, and suprasellar tumors (i.e., macroadenomas, craniopharyngiomas, meningiomas, and optic gliomas). The clinical presentation varies with tumor location in and around the third ventricle. Tumors of the inferior portion of the anterior third ventricle can cause endocrine complaints, including diabetes insipidus and hypopituitarism as well as visual field impairment. Tumors of the superior portion of the anterior third ventricle result in obstructive hydrocephalus and cognitive memory deficits. Tumors of the posterior third often create outflow obstruction and hydrocephalus, and pineal region tumors are associated with Parinaud syndrome. Multiple surgical approaches may be considered in resecting tumors of the third ventricular region, including transcortical or interhemispheric transcallosal, interforniceal, transforaminal, orbitozygomatic subfrontal, or infratentorial supracerebellar. Each approach has strengths and weaknesses, and the choice is often made according to the surgeon’s experience and comfort level. The goals of surgery must be carefully considered so as to minimize neurologic morbidity or mortality. Finally, adjuvant chemotherapy and/or radiation therapy may play a significant role in treating tumor after tissue diagnosis.

Surgical approaches to pineal region tumors.

Direct surgical resection of pineal region tumors has become safer, more effective, and now plays an essential role in their management. Tissue diagnosis allows for the initiation of appropriate therapies and resection can be curative or improve the efficacy of adjuvant therapies. Several approaches have been reported. Based on our operative experience with 57 patients over a 20-year period, we conclude that the Infratentorial Supracerebellar and Parieto-Occipital Paramedian Transtentorial approaches provide excellent exposure while allowing minimally invasive, relatively low risk access to the majority of pineal region tumors. Indications, positioning, techniques, advantages, and disadvantages are discussed. A review of other approaches, pertinent historical remarks, and a discussion of the role of surgery in the contemporary management of pineal region tumors are presented.

Pineal region tumor: surgical anatomy and approach.

The pineal region is one of the surgically inaccessible areas in the brain. Many neurovascular structures form a formidable obstacle to the operative approach to this region. The approaches suitable for reaching the pineal region are the infratentorial supracerebellar, occipital transtentorial, posterior transcallosal, posterior transcortical and posterior subtemporal routes. Considerations important in selecting one of these surgical approaches are reviewed from the anatomical viewpoint.

Functional results after microsurgical resection of brain stem cavernous malformations (retrospective study of a 12 patient series and review of the recent literature).

Since advent of MRI, brain stem Cavernous Malformations (CM) can be easily diagnosed, and their curative surgical resection considered under precise conditions. The authors report a consecutive series of twelve patients with CMs surgically treated and histopathologically confirmed. Eleven of the cases had bled (six more than once). In this study special emphasis has been put on the pre and post-operative functional status of the patients, by using the 100 Karnofsky scale (KS). Surgical approaches were: 1) supra-occipital transtentorial for 1 thalamomesencephalic and 1 quadrigeminal plate CM, 2) suboccipital infratentorial supracerebellar for 1 dorsolateral mesencephalic CM, 3) retrosigmoid through the cerebello-pontine angle for 3 pontine and/or medullary CM, 4) suboccipital intertonsillar for 6 CM located under the floor of the IVth ventricle. Completeness of removal was checked by postoperatoire MRI. It was complete in 11 cases and only partial in 1 (i.e., in the case with the progressing mass-effect presentation). There was no post-op death. Follow-up ranged from 1 to 7 years. Preoperatively: 2 patients were operated on in a comatose state (KS < 20), 5 were in state of functional dependance (K < 60) and 5 had severe neurological deficits but were still of independant functional status (KS > 60). At one year after surgery: 3 patients had a KS > or = 80 (i.e., they could resume their prior normal life), 6 had a KS between 60 and 80 (i.e., they were independant) and 3 had a KS below 60 (i.e., they were dependant especially for walking). Our results, as well as the data harvested from the literature, plead for advocating radical surgical resection at least in patients with exophytic CMs having bled. As a matter of fact, study of the natural history shows that in brain stem CMs, the bleeding risk amounts to 21% per year per patient. Review of literature shows evidence that radiosurgery did not prove effective and/or even innoccuous.

Microsurgical resection of brainstem, thalamic, and basal ganglia angiographically occult vascular malformations.

To evaluate the clinical results for patients who underwent resection of angiographically occult vascular malformations (AOVMs) of the brainstem, thalamus, or basal ganglia, successfully resected after it exhibited rebleeding and presented to a pial surface. Between January 1990 and May 1998, 56 patients with 57 deep AOVMs underwent 63 operations, at Stanford University Medical Center, to treat AOVMs of the brainstem (42 AOVMs), thalamus (5 AOVMs), or basal ganglia (10 AOVMs). The surgical approach was suboccipital midline (27 operations), far lateral suboccipital (10 operations), transsylvian (9 operations), interhemispheric transcallosal or infracallosal (8 operations), infratentorial supracerebellar (6 operations), or subtemporal (3 operations). Four patients experienced recurrent bleeding from the same lesion after surgical resection, requiring a second operation. One patient required a planned second operation, using a different approach, to completely resect the lesion, and one patient underwent two surgical procedures to resect two separate brainstem AOVMs. One patient initially underwent exploration but not resection of her AOVM, because it did not present to a pial or ependymal surface. The AOVM was successfully resected after it exhibited rebleeding and presented to a pial surface. The immediate outcomes after surgery were unchanged for 31 patients (55%), worsened for 16 (29%), and improved for 9 (16%). The long-term outcomes were unchanged for 24 patients (43%), compared with their presenting grade, worse for 3 (5%), and improved for 29 (52%). Patients who had undergone previous radiotherapy or radiosurgery to treat these lesions experienced more difficult postoperative courses, and radiation necrosis was observed for two patients. AOVMs of the brainstem, thalamus, and basal ganglia can be safely removed, with a long-term neurological morbidity rate of only 5% and a complete lesion resection rate of 93% after the initial planned resection. The use of cranial base surgical approaches and intraoperative electrophysiological monitoring contributes to successful clinical outcomes.

Preservation of large bridging veins during brain retraction. Technical note.

✓ The authors describe a method for preserving large bridging veins during neurosurgical procedures by stripping them from the cortex. This technique was used in 81 procedures involving a subtemporal, interhemispheric, infratentorial supracerebellar, and transsylvian approach. Although a small amount of the cortex was often sacrificed, preservation of the vein was easy, and postoperative morbidity was minimized.

Microsurgery of the Third Ventricle: Part 2

The operative approaches to the 3rd ventricle are divided on the basis of whether they are suitable for reaching the anterior or posterior part of the 3rd ventricle. The approaches suitable for lesions within or compressing the anterior portion of the 3rd ventricle are the trans-sphenoidal, subfrontal, frontotemporal, subtemporal, anterior transcallosal, and anterior transventricular. The approaches suitable for reaching the posterior portion of the 3rd ventricle are the posterior transcallosal, posterior transventricular, occipital transtentorial, and infratentorial supracerebellar. Considerations important in selecting one of these approaches are reviewed.