Extreme Lateral Supracerebellar Infratentorial Approach Research Articles

Posterior Cerebral Artery–to–Superior Cerebellar Artery Side-to-Side Bypass via Extreme Lateral Supracerebellar Infratentorial Approach: Technical Note

Background and objectiveDifficult-to-treat aneurysms of the distal posterior cerebral artery (PCA) can often be treated by parent artery occlusion. A cerebrovascular bypass can complement PCA occlusion to curb the risk of ischemic complications.An in-situ bypass may be considered when the occipital artery or superficial temporal artery cannot serve as a bypass donor.This paper describes the use of a side-to-side bypass of superior cerebellar artery (SCA) as a donor to the posterior cerebral artery (PCA) via an extreme lateral supracerebellar infratentorial (ELSCIT) approach. This bypass approach can be a useful surgical strategy for PCA revascularization. MethodsA 40-year-old female patient underwent a side-to-side PCA-SCA bypass via the ELSCIT approach for the treatment of a complex and previously coiled PCA aneurysm.Bypass was followed by endovascular aneurysm and parent artery occlusion. ResultsPostoperatively, the patient experienced transient, partial trochlear nerve palsy of the left eye without ischemic lesions on MRI. The clinical condition was stable and angiography showed a patent bypass and complete aneurysm occlusion 12 months after surgery. ConclusionThe ELSCIT-approach offers access to the medial and distal PCA that is well suitable for a side-to-side PCA-SCA bypass. This type of approach and bypass may be of value when revascularization of a P2-P3 portion of the PCA is needed, but a suitable occipital artery (OA) or superficial temporal artery (STA) is not available.

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.

Endoscope-Assisted Extreme Lateral Supracerebellar Infratentorial Approach for Resection of Superior Cerebellar Peduncle Pilocytic Astrocytoma: Technical Note.

(1) Background: Superior cerebellar peduncle (SCP) lesions are sparsely reported in the literature. The surgical approaches to the cerebello-mesencephalic region remain challenging. In this article, we present the extreme lateral supracerebellar infratentorial (ELSI) approach to treat a large hemorrhagic pilocytic astrocytoma of the SCP. (2) Methods: An 11-year-old boy, known for neurofibromatosis Type I, presented to the emergency department of our institution with symptoms and signs of intracranial hypertension. The cerebral magnetic resonance imaging (MRI) revealed a large hemorrhagic lesion centered on the SCP provoking obstructive hydrocephalus. Following an emergency endoscopic third ventriculocisternostomy (ETV), he underwent a tumor resection via an endoscope-assisted ELSI approach. (3) Results: ELSI approach allows for a wide exposure with direct access to lesions of the SCP. The post-operative course was uneventful, and the patient was discharged home on post-operative day 5. Post-operative MRI revealed a near total resection with a small residual tumor within the mesencephalon. (4) Conclusion: ELSI approach offers an excellent exposure with the surgical angles necessary for median and paramedian lesions. The park-bench position with appropriate head flexion and rotation offers a gravity-assisted relaxation of the tentorial and petrosal cerebellar surfaces. The endoscope can be an adjunct to illuminate the blind areas of the surgical corridor for an improved tumor resection without significant cerebellar retraction.

Technical Note: Extreme Lateral Supracerebellar Approach for Resection of Superior Cerebellar Peduncle Arteriovenous Malformations.

The surgical approaches to the region of the cerebello-mesencephalic sulcus and superior cerebellar peduncle (SCP) remain a neurosurgical challenge. To present the use of the extreme lateral supracerebellar infratentorial (SC-IT) approach to treat arteriovenous malformations (AVMs) of the SCP, which is a different entity compared to brainstem AVMs. We treated 4 patients with SCP AVMs in the last 5 yr at our institution. The mean age was 49.7 yr. The average nidus size was 2.12 cm. Of those, 3 patients presented with hemorrhage and 1 with headache and tinnitus. Extreme lateral SC-IT approach was used in all cases. Complete resection was achieved in all cases as verified with postoperative angiogram. In 1 case, intraoperative rupture with intraventricular hemorrhage was encountered, and the patient required temporary external ventricular drainage. There was no permanent complication or neurological deficit. The modified Rankin Scale (at discharge or follow-up) was less than 2 in all cases. The AVMs located primarily in the SCP are distinct compared to brainstem AVMs, and their management should be different. Extreme lateral SC-IT approach should be considered as a viable alternative surgical approach for resection of these AVMs, and excellent surgical results can be achieved.

RESECCIÓN MICROQUIRURGICA DE UN CAVERNOMA PONTINO MEDIANTE UN ABORDAJE SUPRACEREBELOSO INFRATENTORIAL EXTREMO LATERAL

Introduction: Cavernomas on the posterolateral pontomesencephalic surface can be approached from an extreme lateral supracerebellar infratentorial corridor, although the theory is scarce. The brainstem has a dense concentration of nuclei and fibers that are responsible for a high rate of morbidity when treating brainstem lesions. The objective of this work is to demonstrate the safe microsurgical resection technique for the complete removal of a pontine cavernoma. Clinical Case: 27-year-old woman with a 5-month history of disease; characterized by headache, left facial paresis and right half body paresis. Magnetic resonance imaging (MRI) showed a hemorrhage in the middle cerebellar peduncle compatible with a ruptured cavernoma, initially receiving medical treatment. Subsequently, due to an increase in the motor deficit and the presence of keratopathy in the left eye, surgery was decided. A retromastoid craniotomy and an extreme lateral supracerebellar infratentorial approach were performed. A safe entry zone was identified and the cavernoma was completely excised. In the postoperative period, she did not present additional neurological deficit, being extubated at 24 hours, with a score on the Glasgow scale of 15 points. Postoperative brain tomography (CT) showed the absence of the cavernoma. Conclusion: The far lateral supracerebellar infratentorial approach is safe for the excision of cavernomas with a middle cerebellar peduncle. When combined with the significant reverse Trendelenburg position it results in minimal cerebellar retraction as the cerebellum descends with gravity. Keywords: Hemangioma, Cavernous, Pons, Middle Cerebellar Peduncle, Craniotomy (source: MeSH NLM)

Extreme lateral supracerebellar infratentorial approach: how I do it.

The extreme lateral supracerebellar infratentorial (ELSI) approach was initially proposed to treat lesions of the posterolateral surface of the pons principally cavernomas. The versatility of the approach allowed its use for other pathologies like gliomas, aneurysms, epidermoids, and meningiomas. We describe here the ELSI approach along with its advantages and limits in comparison with other surgical approaches for the treatment of meningiomas of the petroclival region. ELSI is a versatile approach that allows access to the anterolateral brainstem surface including extensions to the midbrain diencephalic junction when needed. ELSI compares favorably to other surgical alternatives with respect to the approach-related morbidity, while allowing adequate access to treat the pathology.

Endoscope-Assisted Microsurgical Approach to the Posterior and Posterolateral Incisural Space

Despite recent technological advances, direct approaches to the posterolateral incisural space remain surgical challenges. The choice of the operative route depends on the exact location and extent of the target lesion as well as individual preferences. The extreme lateral infratentorial supracerebellar approach to treat pathologies located in the ambient cistern and posterior incisural space is a technically feasible route in selected cases. In this cadaveric study, we demonstrate the benefits of endoscope-assisted microsurgical maneuvers using the extreme lateral supracerebellar infratentorial approach. An endoscope-assisted infratentorial supracerebellar approach was performed in six formalin-fixed cadaveric heads using standard microneurosurgical methods. Dissections were performed in a stepwise fashion, comparing the exposure afforded by the microsurgical route alone to the endoscope-assisted route, using 0- and 30-degree angled lenses. Relationships among the target and the surroundings neurovascular structures were described. Endoscope-assisted maneuvers for the extreme lateral supracerebellar approach provide an improved operative view and have the potential to reduce parenchymal trauma and neurovascular injuries. The endoscopic techniques bring the surgeon to the anatomy, enhancing illumination and surgical visualization. Direct visualization of the posterior and posterolateral incisural space avoids retraction of the occipital lobe and damage to the deep venous complex. The extreme lateral infratentorial supracerebellar corridor is effective for approaching the posterolateral mesencephalic junction and the posterior incisural space in selected cases. Endoscope-assisted microsurgery can improve visualization and minimize parenchymal retraction, which should enhance surgical control.

Microanatomical study of the endoscopy-assisted extreme lateral supracerebellar infratentorial keyhole approach to the dorsolateral mesencephalon region

Objective To explore the microanatomy technique of the endoscopy-assisted extreme lateral supracerebellar infratentorial keyhole approach and clinical significance.Methods The extreme lateral supracerebellar infratentorial keyhole approach was imitated in 10 vascular perfusion adult cadaveric heads fixed in formalin,the dorsolateral mesencephalon region was dissected and observed by microscopy and neuroendoscopy from December 2012 to March 2013.Results The extreme lateral supracerebellar infratentorial keyhole approach could be fully exposed the ambient cisterns,the posteromedial tentorial incisura,the dorsolateral mesencephalon region,the trochlear nerve,the root of the trigeminal nerve,the superior cerebellar artery,the posterior cerebral artery and other important anatomical structures.The temporal lobe and parahippocampal gyrus could be exposed when the tentorial was incised.The application of neuroendoscopy could clearly reveal the trigeminal nerve and surrounding structures.Conclusion The extreme lateral supracerebellar infratentorial keyhole approach is suitable for the surgical resection in dorsolateral mesencephalon region.The application of neuroendoscopy can make up for the lack of the trigeminal nerve observed under microscopy and expand the operative field. Key words: Extreme lateral supracerebellar infratentorial approach ; Keyhole approach ; Neuroendoscopy ; Mesencephalon; Microanatomy

A young and booming approach: the extreme lateral supracerebellar infratentorial approach

Surgical accesses to lesions of the posterolateral pontomesencephalic junction (PMJ) region and the posterolateral tentorial gap remain a challenge in the field of neurosurgery. Since the first report of application of the extreme lateral supracerebellar infratentorial (ELSI) approach in resecting the PMJ lesions in 2000, a few articles concerning the ELSI approach have been published. The present review mainly provided an intimate introduction of the ELSI approach, and evaluated it in facets of patient position, skin incision, craniectomy, draining veins, retraction against the cerebellum, exposure limits, patient healing, as well as advantages and limitations compared with other approaches. The ELSI approach is proposed to be a very young and promising approach to access the lesions of posterolateral PMJ region and the posterolateral tentorial gap. Besides, it has several advantages such as having a shorter surgical pathway, causing less surgical complications, labor-saving, etc. Still, more studies are needed to improve this approach.

Tentorial Incision in a Lateral-medial Direction with Minimal Retraction of the Temporal Lobe in the Subtemporal Transtentorial Approach to the Middle Tentorial Incisural Space

The subtemporal transtentorial approach provides excellent exposure of the middle incisural space. A modification of the subtemporal transtentorial approach with use of a partial mastoidectomy is presented to avoid damage to the temporal lobe as a result of retraction as well as damage to venous structures. Four patients, one with a superior cerebellar artery aneurysm, one with a metastatic tumor in the midbrain, one with a tentorial meningioma, and one with a tentorial schwannoma were treated with the present approach. After subtemporal craniotomy, all of the cortical bone overlying the mastoid was removed. The mastoid air cells were drilled down, and the upper part of Trautman's triangle was exposed above the level of the lateral semicircular canal. The presigmoid dura and the temporal dura were opened and connected by incising the superior petrosal sinus. The cerebellar tentorium was incised in a lateral-medial direction along the angle of the tentorium. In each case, the tentorium was incised with minimal retraction of the temporal lobe without any damage to the temporal lobe, or venous structures. The present approach yielded excellent visualization of the lesion and adjacent neurovascular structures. In 3 of 4 cases, the lesions were successfully treated. In the patient with a tentorial schwannoma extending from the middle to posterior incisural space, the extreme lateral supracerebellar-infratentorial approach was combined with the present approach. Although additional partial mastoidectomy is time-consuming, it reduces the risk of damage to the temporal lobe as a result of retraction as well as damage to venous structures.