Cerebrospinal fluid leakage prevention using the anterior transpetrosal approach with versus without postoperative spinal drainage: an institutional cohort study.

The efficacy of spinal drain (SD) placement for cerebrospinal fluid (CSF) leakage prevention after the anterior transpetrosal approach (ATPA) remains unclear. Thus, we aimed to assess whether postoperative SD placement improved postoperative CSF leakage after a skull base reconstruction procedure using a small abdominal fat and pericranial flap and clarify whether bed rest with postoperative SD placement increased the length of hospital stay. This retrospective cohort study included 48 patients who underwent primary surgery using ATPA between August 2011 and February 2022. All cases underwent SD placement preoperatively. First, we evaluated the necessity of SD placement for CSF leakage prevention by comparing the postoperative routine continuous SD placement period to a period in which the SD was removed immediately after surgery. Second, the effects of different SD placement durations were evaluated to understand the adverse effects of SD placement requiring bed rest. No patient with or without postoperative continuous SD placement developed CSF leakage. The median postoperative time to first ambulation was 3 days shorter (P < 0.05), and the length of hospital stay was 7 days shorter (P < 0.05) for patients who underwent SD removal immediately after surgery (2 and 12 days, respectively) than for those who underwent SD removal on postoperative day 1 (5 and 19 days, respectively). This skull base reconstruction technique was effective in preventing CSF leakage in patients undergoing ATPA, and postoperative SD placement was not necessary. Removing the SD immediately after surgery can lead to earlier postoperative ambulation and shorter hospital stay by reducing medical complications and improving functional capacity.

Risk of postoperative scalp necrosis in the occipital artery region after posterior cranial fossa surgery.

Ischemia-induced postoperative scalp necrosis in the superficial temporal artery (STA) region is known to occur after STA-middle cerebral artery anastomoses. However, no reports have evaluated the risk of postoperative scalp necrosis in the occipital artery (OA) region. This study examined the surgical procedures that pose a risk for postoperative scalp necrosis in the OA region following posterior cranial fossa surgery. Patients who underwent initial posterior fossa craniotomy at our institution from 2015 to 2022 were included. Clinical information was collected using medical records. Regarding surgical procedures, we evaluated the incision design and whether a supramuscular scalp flap was prepared. The supramuscular scalp flap was defined as a scalp flap dissected from the sternocleidomastoid and/or splenius capitis muscles. A total of 392 patients were included. Postoperative scalp necrosis occurred in 19 patients (4.8%). There were 296 patients with supramuscular scalp flaps, and supramuscular scalp flaps prepared in all 19 patients with postoperative necrosis. Comparing incision designs among patients with supramuscular scalp flap, a hockey stick-shaped scalp incision caused postoperative necrosis in 14 of 73 patients (19.1%), and the odds of postoperative scalp necrosis were higher with the hockey stick shape than with the retro-auricular C shape (adjusted odds ratio: 12.2, 95% confidence interval: 3.86-38.3, p = 0.00002). In all the cases, ischemia was considered to be the cause of postoperative necrosis. The incidence of postoperative necrosis is particularly high when a hockey stick-shaped scalp incision is combined with a supramuscular scalp flap.

Anatomical variations and flow alterations of the uncal vein and its clinical implications in petroclival meningiomas.

BACKGROUND: The Uncal vein (UV), downstream of the deep middle cerebral vein (DMCV), has a similar drainage pattern to the superficial middle cerebral vein (SMCV) and may be involved in venous complications during the anterior transpetrosal approach (ATPA). However, in petroclival meningioma (PCM), where the ATPA is frequently used, there are no reports evaluating drainage patterns of the UV and the risk of venous complications associated with the UV during the ATPA. METHODS: Forty-three patients with petroclival meningioma (PCM) and 20 with unruptured intracranial aneurysm (control group) were included. Preoperative digital subtraction angiography was used to evaluate UV and DMCV drainage patterns on the side of the tumor and bilaterally in patients with PCM and the control group, respectively. RESULTS: In the control group, the DMCV drained to the UV, UV and BVR, and BVR in 24 (60.0%), eight (20.0%), and eight (20.0%) hemispheres, respectively. Conversely, the DMCV in the patients with PCM drained to the UV, UV and BVR, and BVR in 12 (27.9%), 19 (44.2%), and 12 (27.9%) patients, respectively. The DMCV was more likely to be drained to the BVR in the PCM group (p < 0.01). In three patients with PCM (7.0%), the DMCV drained only to the UV, and furthermore, the UV drained to the pterygoid plexus via the foramen ovale, posing a risk for venous complications during the ATPA. CONCLUSIONS: In the patients with PCM, the BVR functioned as a collateral venous pathway of the UV. Preoperative evaluation of the UV drainage patterns is recommended to reduce venous complications during the ATPA.

Intravenous sinus meningioma with intraluminal extension to the internal jugular vein: case report and review of the literature.

BACKGROUND: Meningiomas often invade venous sinuses, but intravenous sinus meningiomas remain within the intracranial cavity. This case report describes an extremely rare case of tentorial meningioma with venous sinus invasion, extending intraluminally into the lower part of the internal jugular vein in a 59-year-old man. CASE PRESENTATION: The patient's initial surgery involved the supratentorial component of a right tentorial meningioma, which invaded the right transverse and sigmoid sinuses. The supratentorial component of the tumour did not enlarge during the 2-month waiting period for the first surgery. The patient received postoperative radiation therapy for the residual tumour in the intravenous sinus. Despite radiation, the residual tumour developed caudally and ultimately extended into the right internal jugular vein. The average regrowth speed of the extracranial mass was 3.6 mm/month. The patient underwent surgery for the recurrent tumour located in the transverse sinus, sigmoid sinus, jugular bulb, and internal jugular vein, 46 months after the initial surgery. The pathological features of both surgeries were the same; WHO grade I meningothelial meningioma. CONCLUSIONS: To the best of our knowledge, there have been few case reports of benign meningioma with intraluminal extension into the internal jugular vein, and there have been no reports of long-term observation of such cases. Detailed observation of the present case suggests that the difference in growth speed between the intracranial and venous cavity depends on the surrounding environment.

Radiation-induced anterior inferior cerebellar artery pseudoaneurysm after stereotactic radiosurgery for vestibular schwannoma: features observed by direct surgery.

BACKGROUND: In vestibular schwannoma (VS) patients treated with stereotactic radiosurgery (SRS), radiation-induced pseudoaneurysm is a rare long-term complication. To the best of our knowledge, there has been only one report of direct surgery in ruptured cases, and the optimal strategy for direct surgery is yet to be clarified. This case report describes a case of ruptured VS-related SRS-induced pseudoaneurysm that was successfully treated by direct surgery. CASE PRESENTATION: A 57-year -old man underwent SRS for VS, and the tumour was well controlled after the SRS. Nine years after the SRS, however, he developed subarachnoid haemorrhage, and a SRS-induced distal anterior inferior cerebellar artery aneurysm was detected on the surface of the tumour. During the trapping surgery, the aneurysm was embedded in the tumour, and it was difficult to separate the aneurysm and tumour. Besides, the facial nerve and tumour restricted exposure of the parent artery. The parent artery proximal to the aneurysm could only be exposed by resecting caudal part of the tumour. The aneurysm was trapped with permanent clips and it was pathologically diagnosed as pseudoaneurysm. CONCLUSION: It was suggested that the VS-related SRS-induced pseudoaneurysm is tightly adhered with surrounding structures and exposure of the parent artery could be limited due to the tumour and facial nerve. In this case report, we describe detailed intraoperative findings that will be useful for developing strategies for trapping surgery in future.

Intracranial phosphaturic mesenchymal tumors. A case report and review of literature.

Most osteomalacia-inducing tumors (OITs) are phosphaturic mesenchymal tumors (PMTs) that secrete fibroblast growth factor 23 (FGF23). These tumors usually occur in the bone and soft tissues, and intracranial OITs are rare. Therefore, intracranial OIT is difficult to diagnose and treat. This paper presents a case of intracranial OIT and shows a review of previous cases. A 45-year-old man underwent nasal cavity biopsy and treatment with active vitamin D3 and neutral phosphate for hypophosphatemia. Amplification of FGF23 mRNA level within the tumor was detected. Subsequently, the surgical specimen was diagnosed with a PMT and was considered the cause of the patient's osteomalacia. The patient was referred to a neurosurgery department for the excision of the intracranial tumor extending to the nasal cavity. After tumor removal, the serum levels of FGF23 and phosphorus were normalized as compared to preoperative those. The patient remains disease-free, without additional treatment, approximately 10 years after surgery, with no tumor recurrence. As per the literature, intracranial OITs usually occur in patients aged 8-69 years. Bone and muscle pain are major complaints. Approximately 60% of the patients reported previously had symptoms because of intracranial tumors. In some cases, it took several years to diagnose OIT after the onset of the osteomalacia symptoms. Laboratory data in such cases show hypophosphatemia and elevated FGF23 levels. Because FGF23 levels are associated with the severity of osteomalacia symptoms, total tumor resection is recommended. PMT and hemangiopericytoma (HPC) are histologically similar, but on immunochemistry, PMT is negative for signal transducer and activator of transcription 6 (STAT6), whereas HPC is positive. FGF23 amplification is seen in PMTs but not in HPCs. Therefore, the analysis of FGF23 and STAT6 was helpful in distinguishing PMTs from HPCs. In cases of hypophosphatemia and osteomalacia without a history of metabolic, renal, or malabsorptive diseases, the possibility of oncogenic osteomalacia should be considered.

Epidural and subdural interdural approach to the lateral wall of the cavernous sinus for preserving the laterocavernous sinus in trigeminal schwannoma.

Evacuation of middle fossa trigeminal schwannomas (TS) warrants a subtemporal interdural approach through the lateral wall of the cavernous sinus (CS). The dura comprises the dura propria, which follows the trigeminal nerve and develops into the epineurium, and periosteal layer. The interdural approach involves peeling off the dura propria and exposing the epineural sheath. The venous route around the CS is often obstructed due to TS progression. The interdural approach based on venous route preservation remains to be discussed. The laterocavernous sinus (LCS) is formed in these layers, draining to either the medial or lateral route. In the lateral route, the LCS drains to the pterygoid plexus via the middle cranial fossa foramen. Exposure of the interdural space disturbs the lateral route's venous flow. We describe an operative strategy for venous route preservation in TS via the LCS lateral route. The venous route can be preserved by peeling off the dura propria from the posterior end of the foramen ovale short of the venous drainage route to the pterygoid plexus epidurally and then cutting from the middle cranial fossa dura posterior to the venous route subdurally to the exposed interdural space. This technique helps in avoiding postoperative venous complications.

Evaluating diploic vein blood flow using time-resolved whole-head computed tomography angiography and determining the positional relationship between typical craniotomy approaches and diploic veins in patients with meningioma.

BACKGROUND: Diploic veins may act as collateral venous pathways in cases of meningioma with venous sinus invasion. Diploic vein blood flow should be preoperatively evaluated to consider preserving the veins. In this study, we evaluated the use of time-resolved whole-head computed tomography angiography (4D-CTA)-which is less patient-intensive than digital subtraction angiography (DSA)-for assessing diploic vein blood flow and the positional relationship between typical craniotomy approaches and diploic veins. METHODS: We retrospectively examined 231 patients who underwent surgery for intracranial meningioma. We performed contrast-enhanced magnetic resonance imaging (MRI) to evaluate diploic vein pathways and compared the visualization rates of diploic vein blood flow assessed using 4D-CTA and DSA. Subsequently, we evaluated the rates of the diploic veins transected during craniotomy by comparing the pre- and postoperative contrast-enhanced MRI. RESULTS: The diagnostic performance of 4D-CTA was assessed in 45 patients. Of the 320 diploic veins identified in these patients, blood flow in 70 (21.9%) diploic veins was identified by 4D-CTA and DSA, and both results were consistent. To assess the transection rates of the diploic veins, 150 patients were included. A trend towards a high transection rate of the diploic vein in the basal interhemispheric, frontotemporal, orbitozygomatic, combined transpetrosal, and convexity craniotomy approaches was observed. CONCLUSIONS: In patients with meningiomas, both 4D-CTA and DSA are useful in evaluating diploic vein blood flow. In meningiomas with venous sinus invasion, determining the extent of craniotomy after understanding the pathways and blood flow of diploic veins is recommended.

Objective and quantitative evaluation of angiographic vascularity in meningioma: parameters of dynamic susceptibility contrast-perfusion-weighted imaging as clinical indicators of preoperative embolization.

Digital subtraction angiography (DSA) assesses the necessity of preoperative embolization in meningioma cases but entails complication risks. Previous studies evaluating meningiomas' angiographic vascularity using perfusion-weighted imaging (PWI) have performed subjective visual assessments, not managing to assess the need for preoperative embolization. We objectively assessed the angiographic stain of meningiomas and examined the usefulness of two parameters of dynamic susceptibility contrast (DSC)-PWI, normalized cerebral blood volume (nCBV) and cerebral blood flow (nCBF), in predicting vascularity and the necessity of preoperative embolization. We retrospectively examined 52 patients who underwent surgery for primary meningioma and preoperative DSA and DSC-PWI. We calculated the normalized luminance (nLum) of the tumor stain in DSA. In 29 meningioma cases with a single feeding artery, we determined the DSC-PWI parameter that correlated with meningioma angiographic vascularity and predicted the necessity of preoperative embolization. We also compared vascularity between meningiomas with single and multiple feeding arteries and between convexity and skull-base meningiomas. nCBF (cut off: 3.66, P = 0.03, area under the curve [AUC] = 0.80) alone could predict the necessity of preoperative embolization and was more significantly correlated with the nLum than nCBV (P = 0.08, AUC = 0.73). Vascularity did not differ between meningiomas with single and multiple feeding arteries; skull-base meningiomas were more vascularized than convexity meningiomas (P = 0.0027). Our objective, quantitative assessments revealed nCBF as the most suitable parameter for evaluating meningioma vascularity. Tumor vascularity assessment using nCBF values and CBF images may aid predicting the necessity of preoperative DSA.

Intraoperative real-time near-infrared optical imaging for the identification of metastatic brain tumors via microscope and exoscope.

OBJECTIVE: As chemotherapy and radiotherapy have developed, the role of a neurosurgeon in the treatment of metastatic brain tumors is gradually changing. Real-time intraoperative visualization of brain tumors by near-infrared spectroscopy (NIRS) is feasible. The authors aimed to perform real-time intraoperative visualization of the metastatic tumor in brain surgery using second-window indocyanine green (SWIG) with microscope and exoscope systems. METHODS: Ten patients with intraparenchymal brain metastatic tumors were administered 5 mg/kg indocyanine green (ICG) 1 day before the surgery. In some patients, a microscope was used to help identify the metastases, whereas in the others, an exoscope was used. RESULTS: NIRS with the exoscope and microscope revealed the tumor location from the brain surface and the tumor itself in all 10 patients. The NIR signal could be detected though the normal brain parenchyma up to 20 mm. While the mean signal-to-background ratio (SBR) from the brain surface was 1.82 ± 1.30, it was 3.35 ± 1.76 from the tumor. The SBR of the tumor (p = 0.030) and the ratio of Gd-enhanced T1 tumor signal to normal brain (T1BR) (p = 0.0040) were significantly correlated with the tumor diameter. The SBR of the tumor was also correlated with the T1BR (p = 0.0020). The tumor was completely removed in 9 of the 10 patients, as confirmed by postoperative Gd-enhanced MRI. This was concomitant with the absence of NIR fluorescence at the end of surgery. CONCLUSIONS: SWIG reveals the metastatic tumor location from the brain surface with both the microscope and exoscope systems. The Gd-enhanced T1 tumor signal may predict the NIR signal of the metastatic tumor, thus facilitating tumor resection.

Diploic veins as collateral venous pathways in patients with dural venous sinus invasion by meningiomas.

BACKGROUND: Although it is known that diploic veins frequently communicate with the dural venous sinuses, the role of diploic veins in patients with venous sinus invasion from meningiomas remains unknown. METHODS: We retrospectively examined the medical records of 159 patients who underwent their first craniotomies for intracranial meningiomas. Contrast-enhanced magnetic resonance imaging was used to evaluate diploic vein routes, and digital subtraction angiography (DSA) was used to evaluate diploic vein blood flow. When high blood flow was visualized concurrently with the venous sinuses, the veins were classified as of the "early type." Diploic vein routes were classified into five routes. RESULTS: DSA was performed in 110 patients, with 14 showing superior sagittal sinus (SSS) invasion (SSS group) and 23 showing non-SSS venous sinus invasion (non-SSS group). The proportion of early type diploic veins was significantly higher in the SSS group (27.1%) than in other patients (patients without venous sinus invasion, 2.1%; non-SSS, 4.3%) (p < 0.01). In patients not in the SSS group, diploic veins were sacrificed during craniotomy in 76 patients, including four patients with veins of the early type. No patients demonstrated new neurological deficits postoperatively. In the SSS group, diploic veins were sacrificed in all patients, and early type diploic veins were cut in five patients. Two of these five patients showed postoperative neurological deficits. CONCLUSIONS: In the SSS group, diploic veins may function as collateral venous pathways, and attention is recommended for their interruption. In patients without SSS invasion, diploic veins, even of the early type, can be sacrificed.

[Oblique Lumbar Interbody Fusion Combined with Minimally Invasive Percutaneous Posterior Instrumentation for Adult Spinal Deformity].

OBJECTIVE: Minimally invasive surgery(MIS)for adult spinal deformity(ASD)is aimed at minimizing perioperative and postoperative complications. However, MIS techniques have been reported to result in suboptimal sagittal plane correction or pseudoarthrosis when used for severe deformities. The authors present their early experience with circumferential MIS(cMIS), which involves oblique lumbar interbody fusion(OLIF)with percutaneous pedicle screw(PPS)fixation using a rod cantilever technique to enhance lumbar lordosis(LL)for ASD. METHODS: Twenty-one thoracolumbar ASD cases in which surgical correction was performed from the lower thoracic spine corresponded to class IIIa in the modified minimally invasive spinal deformity surgery(MISDEF)algorithm. Patients with a rigid curve and prior fusion were excluded. Surgery was performed in 2 stages. During the first stage, OLIF was performed from L1/2 or Th12/L1 to L4/5. After 4 to 7 days, the patients were re-imaged with standing radiography, and the second-stage surgery was performed with L5/S1 posterior lumbar interbody fusion(PLIF)and percutaneous instrumentation from the lower thoracic spine to the pelvis. Radiological deformity correction at 4 weeks and perioperative complications were evaluated. Scatter plots were created for comparison of preoperative and postoperative sagittal spinopelvic parameters. RESULTS: The patients' mean age was 75 years. The mean operative time was 488 min, and the blood loss was 901 mL. Significant improvement in the spinopelvic parameters were found on the preoperative images of the sagittal vertical axis(SVA)(108mm to 33.5 mm), lumbar lordosis(LL)(18° to 48°), pelvic tilt(PT)(31.8° to 19.2°), and Cobb angle(CA)(21.1° to 11.9°). The change from the preoperative to the postoperative sagittal spinopelvic parameters(SVA, PI-LL, and PT)strongly correlated with preoperative values. CONCLUSION: As cMIS resulted in improvement in spinopelvic parameters and no major complications, this technique could provide a safe and effective strategy to manage ASD even with severe sagittal imbalance.

Prediction of genetic subgroups in adult supra tentorial gliomas by pre- and intraoperative parameters.

Recent progress in neuro-oncology has validated the significance of genetic diagnosis in gliomas. We previously investigated IDH1/2 and TP53 mutations via Sanger sequencing for adult supratentorial gliomas and reported that PCR-based sequence analysis classified gliomas into three genetic subgroups that have a strong association with patient prognosis: IDH mutant gliomas without TP53 mutations, IDH and TP53 mutant gliomas, and IDH wild-type gliomas. Furthermore, this analysis had a strong association with patient prognosis. To predict genetic subgroups prior to initial surgery, we retrospectively investigated preoperative radiological data using CT and MRI, including MR spectroscopy (MRS), and evaluated positive 5-aminolevulinic acid (5-ALA) fluorescence as an intraoperative factor. We subsequently compared these factors to differentiate each genetic subgroup. Multiple factors such as age at diagnosis, tumor location, gadolinium enhancement, 5-ALA fluorescence, and several tumor metabolites according to MRS, such as myo-inositol (myo-inositol/total choline) or lipid20, were statistically significant factors for differentiating IDH mutant and wild-type, suggesting that these two subtypes have totally distinct characteristics. In contrast, only calcification, laterality, and lipid13 (lipid13/total Choline) were statistically significant parameters for differentiating TP53 wild-type and mutant in IDH mutant gliomas. In this study, we detected several pre- and intraoperative factors that enabled us to predict genetic subgroups for adult supratentorial gliomas and clarified that lipid13 quantified by MRS is the key tumor metabolite that differentiates TP53 wild-type and mutant in IDH mutant gliomas. These results suggested that each genetic subtype in gliomas selects the distinct lipid synthesis pathways in the process of tumorigenesis.

[Risk Factors for Predicting the Need for Additional Surgery for Symptomatic Adjacent Segment Disease after Minimally Invasive Surgery-Transforaminal Lumbar Interbody Fusion].

PURPOSE: To determine the incidence of and risk factors for symptomatic adjacent segment disease(SASD)requiring additional surgery in patients previously treated with minimally invasive surgery-transforaminal lumbar interbody fusion(MIS-TLIF)for degenerative lumbar disease. MATERIALS AND METHODS: A series of 467 consecutive patients who had undergone MIS-TLIF of one or two segments to treat degenerative lumbar disease was identified. The mean age of the patients at the time of the index operation was 67.7 years and the mean follow-up period was 33.2 months(range, 6.0-110.1 months). The incidence rate of SASD surgeries was calculated using the Kaplan-Meier method. The log-rank test and Cox regression analysis were used for risk factor analysis based on age, sex, number of fused segments, presence of laminectomy adjacent to index fusion, and L1 plumb line. RESULTS: The overall incidence rate of SASD requiring additional surgery was 2.8%. Kaplan-Meier analysis predicted a disease-free rate of adjacent segments in 94.3% of the patients at 4 years and in 90.8% of the patients at 8 years after the index operation. In the analysis of risk factors, a negative L1 plumb line was associated with a 5.6 times higher incidence of SASD requiring additional surgery than that associated with a positive L1 plumb line(p=0.0096). There was no significant difference in the survival rates based on age, sex, number of fused segments, and concomitant laminectomy to adjacent segment. CONCLUSION: Approximately 9.2% of the patients were predicted to undergo additional surgery for treating SASD within 8 years of MIS-TLIF. In this study, presence of a negative L1 plumb line indicated higher incidence of additional SASD associated surgeries than that shown by a positive L1 plumb line. Therefore, surgeons should carefully consider this factor while performing MIS-TLIF.

World Health Organization grade II-III astrocytomas consist of genetically distinct tumor lineages.

Recent investigations revealed genetic analysis provides important information in management of gliomas, and we previously reported grade II-III gliomas could be classified into clinically relevant subgroups based on the DNA copy number aberrations (CNAs). To develop more precise genetic subgrouping, we investigated the correlation between CNAs and mutational status of the gene encoding isocitrate dehydrogenase (IDH) of those tumors. We analyzed the IDH status and CNAs of 174 adult supratentorial gliomas of astrocytic or oligodendroglial origin by PCR-based direct sequencing and comparative genomic hybridization, respectively. We analyzed the relationship between genetic subclassification and clinical features. We found the most frequent aberrations in IDH mutant tumors were the combined whole arm-loss of 1p and 19q (1p/19q codeletion) followed by gain on chromosome arm 7q (+7q). The gain of whole chromosome 7 (+7) and loss of 10q (-10q) were detected in IDH wild-type tumors. Kaplan-Meier estimates for progression-free survival showed that the tumors with mutant IDH, -1p/19q, or +7q (in the absence of +7p) survived longer than tumors with wild-type IDH, +7, or -10q. As tumors with +7 (IDH wild-type) showed a more aggressive clinical nature, they are probably not a subtype that developed from the slowly progressive tumors with +7q (IDH mutant). Thus, tumors with a gain on chromosome 7 (mostly astrocytic) comprise multiple lineages, and such differences in their biological nature should be taken into consideration during their clinical management.

Cerebellopontine angle epidermoid cysts: clinical presentations and surgical outcome.

Epidermoid cysts constitute less than 1% of intracranial tumors with the majority of them involving cerebellopontine angle (CPA). Although several mechanisms for cranial nerve dysfunction due to these tumors have been proposed, no direct evaluation for hyper- or hypoactive dysfunction has been done. In this case series, pathophysiology of cranial nerve dysfunction in CPA epidermoid cysts was evaluated with special attention to a new mechanism of capsule strangulation caused by stratified tumor capsule. Twenty-two cases with epidermoid cysts of CPA micro-neurosurgically treated in our departments since 2005 were reviewed. Clinical status of the patients before the surgery and post-operative functional outcome were recorded. Available data from the English literature were summarized for comparison. Mass reduction of cyst contents in most cases was usually associated with prompt and marked improvement of the symptoms suggesting neuroapraxia caused by compression of the tumor content and/or mild ischemia. Among them, two cases showed strangulation of the affected nerves by the tumor capsule whose preoperative dysfunction did not improve after surgery in spite of meticulous microsurgical removal of the lesion. Involved facial and abducent nerves in these two cases showed distortion of nerve axis and nerve atrophy distal to the strangulation site. We report the first direct evidence of etiology of cranial nerve dysfunction caused by cerebellopontine angle epidermoid tumors. Young age and rapidly progressive neurological deficit might be the characteristics for strangulation of the affected nerves by the cyst capsule. Even though the number of cases might be limited, immediate decompression and release of the strangulating band might be urged in such patients to prevent irreversible deficits.

Neuroepithelial cyst of the fourth ventricle.

PURPOSE: Neuroepithelial cyst is considered an unusual differential diagnosis for cysts in the posterior fossa. Here, we present a paediatric case with such a pathology and review the pertinent literature. METHODS: A 12-year old girl with headache, vertigo and disturbed gait was diagnosed with a cystic lesion in the fourth ventricle after brain MRI study. She was operated with the pre-operative diagnosis of arachnoid cyst. RESULTS: A transparent, colourless cyst was observed intra-operatively. As frozen sections were consistent with endodermal cyst, total removal of the cyst was attempted. Definite histopathological studies and immunohistochemistry stains were in favour of neuroepithelial cyst. No regrowth of the cyst or recurrence of the symptoms was observed in her 2-year follow-up. CONCLUSIONS: As neuroepithelial cyst is rarely encountered in the posterior fossa, the clinical, radiological and pathological characteristics of our case along with similar cases in the literature were reviewed and discussed.

Hemispheric differences in the surgical outcomes of patients with traumatic acute subdural hematoma.

BACKGROUND: Our assumption that prognosis of patients with traumatic acute subdural hematoma (ASDH) does not differ significantly according to the hemispheric laterality has never been verified. METHODS: A review of the charts/radiographic images of 61 adult traumatic ASDH patients (33 left/28 right) was conducted. Intergroup comparison was made on the demographics, autonomic/laboratory data, and outcomes (90-day mortality rate). Based on the presence of concomitant brain contusion, patients were further quadrichotomized as: left ASDH with contusion (n = 14), right ASDH with contusion (n = 16), left ASDH without contusion (n = 19), and right ASDH without contusion (n = 12). Comparisons were made on demographic and outcome variables between the left ASDH with contusion and right ASDH with contusion, and between the left ASDH without contusion and right ASDH without contusion. Multivariate regression analysis was conducted to identify clinical variables correlated with fatality. RESULTS: There were no significant differences in the demographic, autonomic, and laboratory data between the left and right ASDH patients. However, 90-day mortality rate was significantly higher in the left ASDH patients when concomitant contusion was present (79% vs. 25%, p = 0.009). However, there were no significant hemispheric differences in the mortality rate among those without contusion (32% vs. 33%, p = 0.77). Multivariate regression analysis showed that left ASDH was correlated with fatality among those with contusion (OR: 6.620; 95% CI: 1.219-46.249). CONCLUSIONS: This study is probably the first to report that the left ASDH patients fared substantially worse than the right-sided counterparts. Future trials on traumatic ASDHs may benefit from considering hemispheric differences in the outcomes.

Role of a Tortuous Vertebrobasilar Artery and Anchoring Perforators in the Etiology of Hemifacial Spasm.

BACKGROUND: In >70% of patients with hemifacial spasm (HFS), the offending artery is either the anterior inferior cerebellar artery (AICA) or posterior inferior cerebellar artery (PICA), without a tortuous vertebrobasilar artery (VBA). We hypothesized that anchoring perforators around the root exit zone (REZ) of the AICA or PICA might induce vascular deviation and compression. We investigated the occurrence of these perforators from the AICA or PICA and the extent of VBA tortuosity to reveal the pathology of vascular compression. METHODS: This retrospective review included 110 patients after excluding those with vertebral artery (VA) compression alone. The occurrence of perforators was determined according to operative findings within 5 mm of the REZ, and VBA tortuosity was evaluated using MATLAB. We analyzed the association between perforators, VBA tortuosity, and the surgical implications. RESULTS: The occurrence of perforators from the offending AICA or PICA around the REZ was significantly higher in the group without VA compression (Group A) than in the group with VA compression (Group B). VBA tortuosity was significantly lower in Group A. VBA tortuosity was inversely correlated with the presence of AICA or PICA perforators in all 110 patients. Operative results were similar between the groups, although patients with low VBA tortuosity tended to require interposition in decompression procedures. CONCLUSIONS: Anchoring perforators around the REZ play a crucial role in vascular compression for patients with less tortuous VBAs. Moreover, surgeons should be prepared to deal with multiple perforators in a more complicated surgery in cases of less tortuous VBA.