Surgical and radiosurgical outcomes for Koos grade 3 vestibular schwannomas.

This study aimed to reveal the preferred initial treatment for Koos grade 3 vestibular schwannomas (VS). We performed a two-institutional retrospective study on 21 patients with Koos grade 3 VS undergoing resection at Yokohama Medical Center and 37 patients undergoing radiosurgery at Yokohama Rosai Hospital from 2010 to 2021. Tumor control, complications, and functional preservation were compared. The median pre-treatment volume and follow-up duration were 2845 mm3 and 57.0 months, respectively, in the resection group and 2127 mm3 and 81.7 months, respectively, in the radiosurgery group. In the resection group, 16 (76.2%) underwent gross total resection, and three patients (14.3%) experienced regrowth; however, no one required additional treatment. In the radiosurgery group, the tumor control rate was 86.5%, and three cases (8.1%) required surgical resection because of symptomatic brainstem compression. Kaplan-Meier analyses revealed that tumors with delayed continuous enlargement and large thin-walled cysts were significantly associated with poor prognostic factors (p = 0.0027, p < 0.001). The pre-radiosurgery growth rate was also associated with the volume increase (p = 0.013). Two cases (9.5%) required additional operation due to complications such as post-operative hematoma and cerebrospinal fluid leaks in the resection group, whereas temporary cranial neuropathies were observed in the radiosurgery group. Two patients (9.5%) had poor facial nerve function (House-Brackmann grading grade 3) in the resection group, while no one developed facial paresis in the radiosurgery group. Trigeminal neuropathy improved only in the resection group.Radiosurgery can be considered for the treatment of Koos grade 3 VS for functional preservation. However, resection may also be considered for patients with severe trigeminal neuropathy or a high risk of volume increments, such as large thin-walled cysts and rapid pre-treatment growth.

Usefulness of posterior transpetrosal approach for the large solid cerebellopontine angle hemangioblastoma fed from multiple blood supplies: A technical case report.

Background: Extra-axial cerebellopontine angle (CPA) hemangioblastomas are rare clinical entity and surgical treatment is challenging due to the anatomical difficulties and multi-directional blood supplies. On the other hand, the risk of endovascular treatment for this disease has also been reported. Herein, we successfully applied a posterior transpetrosal approach to remove a large solid CPA hemangioblastoma without preoperative feeder embolization. Case Description: A 65-year-old man presented with a complaint of diplopia during downward gaze. Magnetic resonance imaging revealed a solid tumor with homogeneous enhancement measuring about 35 mm at the left CPA, and the tumor compressed a left trochlear nerve. Cerebral angiography disclosed tumor-staining fed by both left superior cerebellar and left tentorial arteries. After the operation, the patient's trochlear nerve palsy improved dramatically. Conclusion: This approach offers more optimal surgical working angle to the anteromedial part compared to the lateral suboccipital approach. In addition, the devascularization from the cerebellar parenchyma can be performed more reliably than the anterior transpetrosal approach. After all, this approach can be particularly useful when vascular-rich tumors receive blood supplies from multiple directions.

Transpetrosal Approach for a Giant Thrombosed P2 Segment Posterior Cerebral Artery Aneurysm.

OBJECTIVE: Posterior cerebral artery (PCA) aneurysms are extremely rare and can be difficult to treat. We report successful trapping and thrombectomy of a giant thrombosed P2 segment aneurysm via a transpetrosal approach. CASE PRESENTATION: A 62-year-old woman was admitted to our hospital with a progressive left hemiparesis. Magnetic resonance imaging (MRI) showed a 30 mm mass lesion in the right ambient cistern. On vertebral angiography, the right P2 trunk was deviated medially and inferiorly, and the right posterior temporal artery (PTA) was not visualized. We diagnosed a giant thrombosed aneurysm of the right PTA. Surgery was performed via a right posterior transpetrosal approach. The proximal P2 was identified above the oculomotor nerve in the ambient cistern, and a giant PTA aneurysm was found. After coagulating the distal PCA, a temporary clip was applied to the proximal P2, the aneurysm wall was incised, thrombus was removed, and a permanent titanium clip was applied to complete trapping. Postoperative MRI showed disappearance of the aneurysm. The patient's left hemiparesis was resolved 2 months after the operation, and she was discharged home. CONCLUSION: Although trans-sylvian and subtemporal approaches are often performed for P2 aneurysms, they have difficulty identifying the distal PCA and may require excessive brain retraction. The transpetrosal approach can also be effective for giant thrombosed P2 aneurysms.

[A Case of Primary Central Nervous System Lymphoma Originated from Optic Chiasma and Presenting Difficulty in Diagnosis].

We report a case of primary central nervous system lymphoma(PCNSL)originating from an optic chiasma, which was difficult to diagnose but was finally diagnosed by biopsy. A 62-year-old immunocompetent man presented with bilateral visual field disturbance, hypopituitarism, and diabetes insipidus;an optic chiasm lesion was detected on MRI. After starting steroid supplementation for adrenal insufficiency, visual field disturbance immediately improved. Since the lesion completely disappeared three months after its onset, it became the follow-up without histological confirmation. Six months after the onset, visual field disturbance progressed, and the lesion recurred. We performed a left optic nerve biopsy to maintain the right visual field, which remained partially. The pathology was PCNSL. We performed postoperative chemoradiotherapy, and the patient showed remission and improvement of the visual field. Isolated PCNSLs arising from optic chiasma are very rare. The diagnosis of optic chiasm lesions is difficult due to their similarity with a variety of inflammatory/autoimmune disease and neoplastic lesions. When a lymphoma is considered to be differentiated, early biopsy should be performed before administering a steroid. The approach and sampling site to prevent the function are also important for biopsy.

Parieto-Occipital Interhemispheric Transfalcine, Trans-Bitentorial Approach for Radical Resection of Falcotentorial Meningiomas.

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.

Superior Oblique Myokymia: A Case Report of Surgical Treatment, Review of the Literature, and Consideration of Surgical Approach.

BACKGROUND: Superior oblique myokymia (SOM) is a rare disorder characterized by episodic microtremor of the eyeball. in patients with SOM, intermittent contraction of the superior oblique muscle causes irregular and rotatory eye movement, causing oscillopsia and diplopia. Microvascular decompression (MVD) of the trochlear nerve is potentially a definitive treatment method for SOM; however, owing to its rarity, this disorder is not well-known to neurosurgeons, and thus the optimal surgical approach has not yet been determined. CASE DESCRIPTION: A 77-year-old woman with left SOM had experienced oscillopsia for 2 years. MVD was performed via a left lateral superior cerebellar approach with the patient in the park-bench position. Her symptom resolved immediately after the surgery. CONCLUSIONS: We believe that MVD via a left lateral superior cerebellar approach can be safely performed to SOM in elderly patients like our patient. Therefore, MVD should be considered as the definitive treatment method for more patients with SOM.

Radical Resection of Craniopharyngioma: Discussions Based on Long-term Clinical Course and Histopathology of the Dissection Plane.

OBJECTIVE: Craniopharyngioma is a benign tumor. However, sometimes, this tumor may recur repeatedly even after apparent total resection. This study investigated the requirements for ideal radical treatment, based on a discussion of the long-term clinical course and pathological findings in surgical patients. METHODS: We performed 81 surgical procedures for 67 patients with craniopharyngioma between February 1990 and December 2015. We classified patients into Groups I-III according to emphasis of surgery in chronological order, so we investigated the tumor recurrence rate and the necessity for postoperative hormonal replacement. RESULTS: Multiple comparison of results from the three groups found significant differences in recurrence rate between Groups I and II (P = 0.0111) and Groups I and III (P = 0.0056). Although there were no differences in recurrence rate between Groups II and III, mortality rate of Group III was lower than that of Group II. No significant difference was seen between any group in terms of hormonal replacement. CONCLUSIONS: These results strongly suggest that the radical resection used to treat patients in Group III should be given priority as the procedure for removing craniopharyngioma.

Intracranial epidermoid cyst with proliferative folliculosebaceous epithelium: Report of a rare case and discussion on pathogenesis.

Intracranial epidermoid cysts are rarely known to increase in size over a brief period. While malignant transformations of epidermoid cyst have been previously described, no reports to date have described rapid proliferation accompanied by mature hair follicles and sebaceous glands without malignant transformations. The present case involved a 71-year-old man who visited a local physician with disturbance of equilibrium. A mass lesion was detected at the left cerebellopontine angle and was subsequently removed. Histopathological diagnosis of this lesion was as an epidermoid cyst. Seventeen years after this initial surgery, worsened left hypoacusis, disorientation, eating disorder and gait disturbance appeared, and the patient visited the physician again. Local recurrence of the lesion was observed, and the patient was referred to our hospital for its removal. Intraoperative findings revealed a pearly white tumor, histopathologically diagnosed as an epidermoid cyst. Three years later, local recurrence was observed, and the cyst was again removed. Intraoperative findings revealed a partially pearly white tumor similar to the tumor observed during the second surgery, but the majority of the tumor was non-shiny, ochre-colored and suckable. Histopathological diagnosis was an epidermoid cyst with an epidermis-like structure. Postoperative activities of daily living were independent thereafter, but from March of the following year, he began to experience increasing difficulty in walking and subsequently visited our hospital again. Tumor recurrence was observed and was removed again in November of the same year. Intraoperative findings revealed a tumor that was primarily ochre-colored, non-shiny, brittle and suckable. The histopathological diagnosis was folliculosebaceous epithelial proliferative lesion accompanied by an epidermis-like epithelium and a differentiation into hair follicles and sebaceous gland,s and the tumor was determined to be an epidermoid cyst with proliferative folliculosebaceous epithelium.

Intraoperative cochlear nerve mapping with the mobile cochlear nerve compound action potential tracer in vestibular schwannoma surgery.

OBJECTIVEThe 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.METHODSThis 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.RESULTSMapping 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).CONCLUSIONSIn 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.

Unicystic Ameloblastomatoid Cystic Craniopharyngioma: Pathological Discussion and Clinical Significance of Cyst Formation in Adamantinomatous Craniopharyngioma.

An 8-year-old boy presented complaining principally of headache and vomiting. A single large cystic lesion extending from the suprasellar region to the ventral brainstem was identified, and total extirpation was performed via a right orbitozygomatic, transtemporal transchoroidal fissure approach. The cyst contents resembled motor oil, and no strong adhesions were identified between the tumor and the surrounding tissue except at the site of origin of the tumor, allowing easy dissection. The tumor originated at the junction of the adenohypophysis and the pituitary stalk. Although the histopathological diagnosis was adamantinomatous craniopharyngioma, the cyst walls comprising the majority of the tumor were not thin, fragile tissues formed by squamous metaplasia, but were thick and robust, bearing a close resemblance to unicystic ameloblastoma mixed with solid tissue. The existence of this type of cyst wall represents corroborating evidence that craniopharyngiomas are derived from the oral primordium. The existence of such tumors that can be totally extirpated in a single procedure while preserving hypothalamo-pituitary function may be taken as a warning not to rush at random to perform treatments that might encourage recurrence or regrowth by carrying out cyst fenestration and drug injection with the addition of stereotactic radiotherapy.

A strongly CD34-positive meningioma that was difficult to distinguish from a solitary fibrous tumor.

Fibrous or transitional meningioma and solitary fibrous tumor (SFT) are frequently difficult to differentiate from each other on the basis of histopathology. It is extremely unusual for a meningioma to exhibit diffuse, strongly positive immunoreactivity for cluster of differentiation 34 (CD34), and this has never been previously reported from a histopathological specimen. A patient with transitional meningioma that exhibited strongly positive for CD34, which has been regarded as characteristic of SFT and is considered to be useful for distinguishing the latter from meningioma, is reported.

Drainage Pathway of the Superior Petrosal Vein Evaluated by CT Venography in Petroclival Meningioma Surgery.

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.

[Deep sylvian meningioma without dural attachment: a case report].

A 34-year-old female presented with an 8-year history of temporal lobe epilepsy. Magnetic resonance imaging showed a multilobular, well-demarcated and homogeneous tumorous lesion of 5 cm in diameter deep in the left sylvian fissure. Intraoperative findings revealed that the tumor was mainly in the left insular region without dural attachment and strongly adhered to the left middle cerebral artery and its perforators. The histopathological diagnosis was transitional meningioma without malignancy. There are few reported cases of deep sylvian meningioma without dural attachment. We review the literature and summarize the clinicopathological characteristics of this condition.