Objective Falcotentorial meningioma occurs close to the falcotentorial edges and the confluence of the vein of Galen. The posterosuperior approach conventionally used to reach this site does not allow direct visualization of the tumor matrix, making detachment difficult. Meningiomas at this location are therefore among those that are not well amenable to radical resection. We devised an alternative anterolateral approach that, when used in addition to the posterosuperior approach, provides an operating field which allows to overview large, bilaterally extending tumors. We report this parieto-occipital interhemispheric transfalcine, trans-bitentorial approach, together with associated procedural modifications. Methods We used the approach in four patients with falcotentorial meningioma between February 2008 and July 2017. We began by extending a parieto-occipital craniotomy slightly beyond the midline, to pass across the most caudal bridging vein on the rostral side. We then created a fan-shaped fenestration as large as possible in the falx, between the superior sagittal sinus and the inferior sagittal and straight sinuses (window 1). We further performed wedge-shaped resections of both tentorial edges to the left and right of window 1 (windows 2 and 3). Tumor debulking was then carried out via these three windows (the triple-window method). Finally, we detached the tumor in the area of the falcotentorial edges and the confluence of the vein of Galen. To obtain a superorostral operating field as wide as possible from laterally, thereby exposing the potential blind spots, the operating surgeon used both hands while retracting the precuneus, and the assistant surgeon used both hands to turn over the falcotentorial edges (twosome four-hand retractorless microsurgery). Results The wide operating field provided by this parieto-occipital interhemispheric transfalcine, trans-bitentorial approach and twosome four-hand retractorless microsurgery provides a direct view of delicate structures at the falcotentorial edges and the confluence of the vein of Galen, a site that is most likely to be a blind spot in conventional approaches. Retraction of the precuneus on the nondominant side enabled radical resection with no neurologic deficit in any of the patients. Conclusions The parieto-occipital interhemispheric transfalcine, trans-bitentorial approach with the triple-window method opens an anterolateral operating field in addition to a posterosuperior operating field in large tumors located in the falcotentorial and pineal region, extending anteroposteriorly and bilaterally. The twosome four-hand retractorless technique via this approach enables visualization of the tumor matrix at sites, which are barely visible with the conventional approach. Thus, the tumor can be removed more radically and safely.
OBJECTIVE The authors describe the usefulness and limitations of the cochlear nerve compound action potential (CNAP) mobile tracer (MCT) that they developed to aid in cochlear nerve mapping during vestibular schwannoma surgery (VSS) for hearing preservation. METHODS This MCT device requires no more than 2 seconds for stable placement on the nerve to obtain the CNAP and thus is able to trace the cochlear nerve instantaneously. Simultaneous bipolar and monopolar recording is possible. The authors present the outcomes of 18 consecutive patients who underwent preoperative useful hearing (defined as class I or II of the Gardner-Robertson classification system) and underwent hearing-preservation VSS with the use of the MCT. Mapping was considered successful when it was possible to detect and trace the cochlear nerve. RESULTS Mapping of the cochlear nerve was successful in 13 of 18 patients (72.2%), and useful hearing was preserved in 11 patients (61.1%). Among 8 patients with large tumors (Koos grade 3 or 4), the rate of successful mapping was 62.5% (5 patients). The rate of hearing preservation in patients with large tumors was 50% (4 patients). CONCLUSIONS In addition to microsurgical presumption of the arrangement of each nerve, frequent probing on and around an unidentified nerve and comparison of each waveform are advisable with the use of both more sensitive monopolar and more location-specific bipolar MCT. MCT proved to be useful in cochlear nerve mapping and may consequently be helpful in hearing preservation. The authors discuss some limitations and problems with this device.
It is widely reported that complete tumor resection is the most certain method for successful radical craniopharyngioma resection. However, radical resection and endocrinic function preservation are often opposing goals in craniopharyngioma surgery. Also, as for the context of total removal , there are no reports that clearly examine the complete total removal method with pathological specimens. Therefore we discuss radical resection that has a high curative rate from the view point of long term prognosis in our experiences. Between 1991 and 2012, 57 patients underwent surgery for craniopharyngioma in 71 instances at our institution. The follow up period ranged from 6 months to 21 years mean 8.4 years. We aimed to remove the tumor totally in almost all cases with a combined supra and infra chiasmatic approach or orbitozygomatic multi trajectory approach. Although the surgical approach should be deliberately selected in order to obtain a better view of the tumor origin and to preserve this axis anatomically priority should be given to radical resection when functional preservation is considered to be impracticable. For many of the non recurrent cases we partially perforated the hypothalamus and removed the tumor totally with the pituitary stalk and gland in recent years, but in a few of the non recurrent cases we removed the tumor totally while preserving the pituitary stalk and gland. So almost all of the non recurrent cases required hormone replacement postoperatively independent of whether we preserve the pituitary stalk and gland or not. The feasibility of functional preservation of the hypothalamic pituitary axis is determined primarily by the exact site of tumor origin, i. e. proximal or distal to the hypothalamus pituitary stalk junction. Finally for the purpose of attaining truly radical resection of the tumor, intraoperative frequent and frozen histopathological examination is mandatory to confirm that accurate surgical margins have been obtained.
Objectives This study aimed to clarify the drainage location of the superior petrosal vein (SPV) in relation to Meckel's cave and the internal acoustic meatus (IAM) and to discuss its significance in petroclival meningioma surgery. Design Prospective clinical study. Setting Hospital-based. Participants Five patients with petroclival meningioma and 50 patients (primarily unruptured supratentorial aneurysm patients, with a few hemifacial spasm patients) with no posterior fossa lesions. Main Outcome Measures On computed tomography venography (CTV), the drainage site was classified into three patterns based on its relationship to Meckel's cave and the IAM: Meckel's cave type, Intermediate type, and Meatal type. Results In all patients, the SPV was patent and emptied into the superior petrosal sinus (SPS). In patients without posterior fossa lesions, 35% had Meckel's cave type, 54% had Intermediate type, and 11% had Meatal type. Of the five patients with petroclival meningioma, three had Intermediate type, and two had Meckel's cave type. Conclusion The SPV is a significant vein that should be preserved to prevent venous complications. Preoperative knowledge of the SPV drainage site is helpful for planning the approach and preserving the SPV in petroclival meningioma surgery.
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