Neuroendoscopic cyst fenestration for delayed enlargement of perianeurysmal cyst formation through long-term follow-up after endovascular treatment: A case report and review of literature.

Background: Perianeurysmal cyst formation after endovascular treatment of cerebral aneurysms is a rare complication; however, the number of reports has gradually increased in recent years due to the development of several endovascular treatments. Case Description: We present a case of delayed perianeurysmal cyst enlargement 8 years after endovascular treatment for multiple recurrences of a large cerebral aneurysm in the anterior communicating artery. The patient presented with obstructive hydrocephalus caused by an enlarged perianeurysmal cyst. The patient underwent cyst fenestration using neuroendoscopy and ventriculoperitoneal shunting, recovered from the clinical symptoms, and had a good prognosis. Histopathological findings showed that the cyst wall contained a fibrotic layer under the monoependymal layer with hemosiderosis without evidence of neovascularization or inflammatory cell infiltration. These findings suggest that the origin of the perianeurysmal cyst wall is not the aneurysm itself but the adjacent brain tissue. Conclusion: Perianeurysmal cysts can develop during long-term follow-up, and clinicians should consider surgical treatment, including cyst fenestration, using neuro-endoscopy if the cyst presents with clinical symptoms.

The importance of considering competing risks in recurrence analysis of intracranial meningioma.

BACKGROUND: The risk of recurrence is overestimated by the Kaplan-Meier method when competing events, such as death without recurrence, are present. Such overestimation can be avoided by using the Aalen-Johansen method, which is a direct extension of Kaplan-Meier that accounts for competing events. Meningiomas commonly occur in older individuals and have slow-growing properties, thereby warranting competing risk analysis. The extent to which competing events are considered in meningioma literature is unknown, and the consequences of using incorrect methodologies in meningioma recurrence risk analysis have not been investigated. METHODS: We surveyed articles indexed on PubMed since 2020 to assess the usage of competing risk analysis in recent meningioma literature. To compare recurrence risk estimates obtained through Kaplan-Meier and Aalen-Johansen methods, we applied our international database comprising ~ 8,000 patients with a primary meningioma collected from 42 institutions. RESULTS: Of 513 articles, 169 were eligible for full-text screening. There were 6,537 eligible cases from our PERNS database. The discrepancy between the results obtained by Kaplan-Meier and Aalen-Johansen was negligible among low-grade lesions and younger individuals. The discrepancy increased substantially in the patient groups associated with higher rates of competing events (older patients with high-grade lesions). CONCLUSION: The importance of considering competing events in recurrence risk analysis is poorly recognized as only 6% of the studies we surveyed employed Aalen-Johansen analyses. Consequently, most of the previous literature has overestimated the risk of recurrence. The overestimation was negligible for studies involving low-grade lesions in younger individuals; however, overestimation might have been substantial for studies on high-grade lesions.

Surgical strategy for intracranial hemorrhage with accidental hypothermia in elderly individuals.

Background: Accidental hypothermia poses a significant threat to the elderly, and its prevalence might increase due to aging and increasing isolation of individuals in Japan. Here, a series of four consecutive cases of accidental hypothermia in elderly patients with intracranial hemorrhage who underwent surgical treatment at our institution is presented. Case Description: All patients were admitted to the emergency department with a diagnosis of intracranial hemorrhage. Among them, two patients experienced acute circulatory failure during emergency surgery, necessitating immediate cardiopulmonary resuscitation. Two other patients required intensive care before surgery; however, one of them exhibited signs of impending cerebral herniation, requiring emergency surgery. Conclusion: Accidental hypothermia poses a significant threat to elderly individuals, carrying a substantial mortality risk and demanding intensive general care. During rewarming, careful considerations must be devoted to potential complications, such as ventricular fibrillation, rewarming shock, bleeding diathesis, and hyperkalemia. Despite these risks, many life-threatening cases necessitate emergency surgery and rewarming procedures in parallel. The formulation of a surgical strategy aimed at mitigating rewarming-related complications should be entrusted to anesthesiologists. Strict follow-up is required to increase intracranial pressure when prioritizing intensive care over surgery.

[A Surgical Case of Hemifacial Spasm Due to Tentorial Meningioma -peritorcular type- in Posterior Fossa].

Hemifacial spasm is commonly caused by compression of the facial nerve due to overlying vessels, and also due to various types of tumor or aneurysm, and other factors. It occurs, although rarely, as a secondary effect of cerebellar or brainstem shift resulting from a tumor. In such a case, the presence of a large tumor often leads to additional neurological deficits. We present a case of hemifacial spasm caused by a peritorcular type of large tentorial meningioma in the posterior fossa. A 68-year-old woman presented with right facial numbness 4 months ago and right hemifacial spasm 2 weeks ago. Upon visiting our hospital, she displayed no neurological deficits other than the right hemifacial spasm. MRI revealed a peritorcular type of large tentorial meningioma in the posterior fossa with perifocal edema. The right cerebellopontine cistern was narrowed, and the cerebellar tonsil was herniated. The right facial nerve ran adjacent to the anterior inferior cerebellar artery (AICA). Angiography showed that only the left posterior meningeal artery (PMA) flowed to the tumor. The loop of the right AICA extended into the right cerebellopontine cistern. After embolization of the PMA, the tumor was surgically removed, leading to an improvement in the patient's hemifacial spasm. Postoperative MRI confirmed complete removal of the tentorial meningioma without any contact with the right facial nerve. The hemifacial spasm was caused secondarily by the cerebellar or brainstem shift due to the large tentorial meningioma in the posterior fossa. This large tumor had not produced any other neurological deficits before the hemifacial spasm appeared. We report this case because it is extremely rare.

[A Surgical Case of Arachnoid Cyst With Rheumatoid Meningitis].

Rheumatoid meningitis is a rare neurological manifestation that is difficult to diagnose. Here we report a 77-year-old woman who developed a left hemiparesis because of an arachnoid cyst with rheumatoid meningitis. The patient had a 13 year history of rheumatoid arthritis, which had been successfully treated. She developed left hemiparesis and visited our hospital. MRI showed a high signal intensity lesion in the right frontal subarachnoid space and an arachnoid cyst on Fluid attenuated inversion recovery (FLAIR). A gadolinium enhanced T1 weighted image revealed associated abnormal enhancement. We removed the arachnoid cyst and diagnosed the patient as having rheumatoid meningitis. Her symptoms and MRI findings improved rapidly by methylprednisolone pulse therapy. Rheumatoid meningitis is rare, but a case of arachnoid cyst associated with rheumatoid meningitis was extremely rare. This is the first report of such a case.

Rate of return to work in patients with stroke under the health and employment support program of Rosai hospitals in Japan.

To facilitate return to work (RTW) in patients with stroke, a health and employment support (HES) program was started at Rosai hospitals in Japan. This study aimed to determine the rate of RTW in patients with stroke under this support program. We collected demographic and clinical data of patients with stroke from the implementation reports of the HES program. The program provided coordinated dual support, such as acute medical treatments, and stroke and vocational rehabilitation on the medical side, and management and support on the workplace side. The primary endpoint was RTW. Successful and unsuccessful RTW were examined using the χ2 test. The RTW rate curves were analyzed using the Kaplan-Meier method. We enrolled 483 patients; 355 (73%) and 128 (27%) patients had successful and unsuccessful RTW, respectively. Stroke types, neurological findings, and activities of daily living were significant factors for RTW. The Kaplan-Meier method revealed that left hemiplegia, right hemiplegia, and neuropsychological deficits, except for combined disability (hemiplegia with neuropsychological deficits), had similar RTW curves with an RTW rate of > 70%.

Favorable prognostic impact of phosphatase and tensin homolog alterations in wild-type isocitrate dehydrogenase and telomerase reverse transcriptase promoter glioblastoma.

Background: Telomerase reverse transcriptase promoter (TERTp) mutations are a biological marker of glioblastoma; however, the prognostic significance of TERTp mutational status is controversial. We evaluated this impact by retrospectively analyzing the outcomes of patients with isocitrate dehydrogenase (IDH)- and TERTp-wild-type glioblastomas. Methods: Using custom next-generation sequencing, we analyzed 208 glioblastoma samples harboring wild-type IDH. Results: TERTp mutations were detected in 143 samples (68.8%). The remaining 65 (31.2%) were TERTp-wild-type. Among the TERTp-wild-type glioblastoma samples, we observed a significant difference in median progression-free survival (18.6 and 11.4 months, respectively) and overall survival (not reached and 15.7 months, respectively) in patients with and without phosphatase and tensin homolog (PTEN) loss and/or mutation. Patients with TERTp-wild-type glioblastomas with PTEN loss and/or mutation were younger and had higher Karnofsky Performance Status scores than those without PTEN loss and/or mutation. We divided the patients with TERTp-wild-type into 3 clusters using unsupervised hierarchical clustering: Good (PTEN and TP53 alterations; lack of CDKN2A/B homozygous deletion and platelet-derived growth factor receptor alpha (PDGFRA) alterations), intermediate (PTEN alterations, CDKN2A/B homozygous deletion, lack of PDGFRA, and TP53 alterations), and poor (PDGFRA and TP53 alterations, CDKN2A/B homozygous deletion, and lack of PTEN alterations) outcomes. Kaplan-Meier survival analysis indicated that these clusters significantly correlated with the overall survival of TERTp-wild-type glioblastoma patients. Conclusions: Here, we report that PTEN loss and/or mutation is the most useful marker for predicting favorable outcomes in patients with IDH- and TERTp-wild-type glioblastomas. The combination of 4 genes, PTEN, TP53, CDKN2A/B, and PDGFRA, is important for the molecular classification and individual prognosis of patients with IDH- and TERTp-wild-type glioblastomas.

Academic Activities of Female Neurosurgeons in All Branch Meetings of the Japan Neurosurgical Society.

This study aims to evaluate the academic activities of female neurosurgeons at all branch meetings of the Japan Neurosurgical Society and identify related issues they encountered. The programs of all seven branch meetings of the Japan Neurosurgical Society (Hokkaido, Tohoku, Kanto, Chubu, Kinki, Chugoku/Shikoku, and Kyushu) were used to determine the number of presentations and chairpersons by sex. The covered period was from January 2008 to December 2020, which was available for viewing during the survey. Of note, only the Kinki branch used data from January 2008 to December 2019. The Neurologia Medico-chirurgica (NMC), the journal of the Japan Neurosurgical Society, was also reviewed to identify publication achievements during the same period. In all seven branches, the percentage of presentations given by female physicians increased from 7.9% in 2008 to 9.6% in 2020 (p < 0.05).Conversely, the percentage of female chairpersons in all branch meetings did not change over time and it was significantly lower (1.1%) than that of female presenters (7.9%) for all branch meetings combined in over 13 years (p < 0.01). In the NMC, the number of articles with female physicians as first authors did not increase or decrease over the years. We conclude that efforts to smoothly promote female neurosurgeons as chairpersons and increase the number of female first authors are necessary to facilitate their academic activities.

5­aminiolevulinic acid induces a radiodynamic effect with enhanced delayed reactive oxygen species production under hypoxic conditions in lymphoma cells: An in vitro study.

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive type of intracranial tumor. However, PCNSL is radiosensitive; thus, whole-brain radiotherapy (WBRT) is often selected as an alternative consolidation therapy. WBRT-related delayed neurotoxicity can affect the quality of life of the elderly. 5-aminolevulinic acid (ALA) is a natural precursor of heme and has been widely used as a live molecular fluorescence marker in brain tumor surgery. Experimental studies have demonstrated that combination therapy with 5-ALA and ionizing irradiation (IR), denoted radiodynamic therapy (RDT), resulted in tumor suppression in cancer, including glioma, melanoma, colorectal cancer, prostate cancer, breast cancer and lung cancer; however, to the best of our knowledge, this method has not been investigated in lymphoma. The present study aimed to investigate the radiodynamic effect of 5-ALA on lymphoma cells in vitro. The synthesis of 5-ALA-induced protoporphyrin IX (PpIX) was assessed under normal and hypoxic conditions in lymphoma cells (Raji, HKBML and TK). Subsequently, the radiodynamic effect of 5-ALA was evaluated using a colony formation assay and reactive oxygen species (ROS) production after RDT was examined using flow cytometry. Finally, the mitochondrial density in the lymphoma cells was evaluated. Lymphoma cells exhibited a high accumulation of 5-ALA-induced PpIX in the flow cytometric analysis, and a decrease in the surviving fraction under IR in cells with 5-ALA treatment compared with cells not treated with 5-ALA in the colony formation assay under normal and hypoxic conditions. Although ROS production 12 h after IR was increased compared with that immediately after IR (0 h), pretreatment with 5-ALA enhanced the delayed ROS production in each lymphoma cell line under normoxic conditions. Raji and TK cells exhibited an increase in ROS production 12 h after IR compared with that at 0 h in the 5-ALA-untreated cells under hypoxic conditions. Raji, HKBML and TK cells exhibited an increase in ROS production 12 h after IR compared with that at 0 h in the 5-ALA-treated cells, while TK cells exhibited enhancement of ROS production 12 h after IR in 5-ALA-treated cells compared with 5-ALA-untreated cells under hypoxic conditions. Other studies have demonstrated that impaired mitochondria damaged by IR produce ROS via the metabolic process, then damage the rest of the surrounding normal mitochondria, consequently propagating oxidative stress within tumor cells and leading to cell death. Thus, we hypothesized that the propagating oxidative stress after IR was associated with mitochondrial density in tumor cells. Namely, high accumulation of 5-ALA-indcued PpIX may promote ROS production in mitochondria of tumor cells after IR, and suppress the cell surviving fraction via the propagation of oxidative stress. In the colony formation assay, Raji cell colony formation was suppressed by RDT with 5-ALA. Simultaneously, the mitochondrial density in the Raji cells was higher than that in other cell lines. Pretreatment with 5-ALA enhanced delayed ROS production after IR in lymphoma cells under normoxic conditions. Under hypoxic conditions, only TK cells exhibited enhancement of ROS production 12 h after IR in the 5-ALA-treated group compared with the 5-ALA-untreated group. Although further studies evaluating the effect of hypoxic conditions in lymphoma cells are needed, the results suggested that RDT with 5-ALA could suppress colony formation under normal and hypoxic conditions in lymphoma cells. Therefore, RDT with 5-ALA is a potential treatment option for PCNSL.

[A Case Of An Elderly Patient With Blake's Pouch Cyst].

Blake's pouch cyst is a congenital disease in which the ventricle enlargement is a non-communicating hydrocephalus. Some elderly patients have a process of the idiopathic normal pressure hydrocephalus (communicating hydrocephalus). We report an elderly patient with Blake's pouch cyst. A 68-year-old man visited our hospital with a gait disturbance that had begun 2 years previously but had become aggravated. He did not have dementia or urinary disturbance. CT scan and MRI showed the hydrocephalus included an IV ventricle, and the cerebrocerebellar fluid space in the posterior fossa was large. A Tap test was positive, so we attempted lumboperitoneal shunt, and his gait disturbance improved.

[A Case of the Internal Carotid Artery Occlusion Immediately After Intravenous Recombinant Tissue Plasminogen Activator Treatment for Contralateral Middle Cerebral Artery Occlusion].

Early recurrent ischemic stroke (ERIS), as well as symptomatic intracranial hemorrhage (SICH) and progressive stroke (PS), causes early neurological deterioration. Here we report a case of a patient with right internal carotid artery (ICA) occlusion immediately after intravenous recombinant tissue plasminogen activator (rt-PA) treatment for left middle cerebral artery (MCA) occlusion. A 79-year-old woman with drowsiness, aphasia and right hemiparesis was brought to our hospital. MRI showed acute infarction in the left internal capsule and occlusion of the left middle cerebral artery. rt-PA was administered intravenously to the patient 2 hours after the onset of the event. Her consciousness disturbance and aphasia improved, but the right hemiparesis did not. We performed emergent endovascular thrombectomy, but the right ICA (cervical portion) was occluded during the surgery. Finally, the endovascular thrombectomy achieved the recanalization of the left MCA and right ICA. When performing intravenous thrombolysis, we should beware the possibility of re-occlusion and prepare for interventional treatment.

Clinicopathologic analysis of pineal parenchymal tumors of intermediate differentiation: a multi-institutional cohort study by the Kyushu Neuro-Oncology Study Group.

PURPOSE: Pineal parenchymal tumors of intermediate differentiation (PPTIDs), which were recognized in the 2007 World Health Organization (WHO) classification, are rare, accounting for less than 1% of all central nervous system tumors. This rarity and novelty complicate the diagnosis and treatments of PPTID. We therefore aimed to evaluate the clinicopathological significance of this tumor. METHODS: At 11 institutions participating in the Kyushu Neuro-Oncology Study Group, data for patients diagnosed with PPTID were collected. Central pathology review and KBTBD4 mutation analysis were applied to attain the diagnostically accurate cohort. RESULTS: PPTID was officially diagnosed in 28 patients: 11 (39%) with WHO grade 2 and 17 (61%) with WHO grade 3 tumors. Median age was 49 years, and the male:female ratio was 1:2.1. Surgery was attempted in all 28 patients, and gross total resection (GTR) was achieved in 46% (13/28). Adjuvant radiotherapy and chemotherapy were administered to, respectively, 82% (23/28) and 46% (13/28). The 5-year progression-free survival (PFS) and overall survival rates were 64.9% and 70.4% respectively. Female sex (p = 0.018) and GTR (p < 0.01) were found to be independent prognostic factors for PFS and female sex (p = 0.019) was that for OS. Initial and second recurrences were most often leptomeningeal (67% and 100% respectively). 80% (20/25) of patients harbored a KBTBD4 mutation. CONCLUSIONS: Female sex and GTR were independent prognostic factors in our patients with PPTID. Leptomeningeal recurrence was observed to be particularly characteristic of this tumor. The rate of KBTBD4 mutation observed in our cohort was acceptable and this could prove the accuracy of our PPTID cohort.

Primary central nervous system lymphoma of the third ventricle with intra-tumoral hemorrhage: A case report and literature review.

Primary central nervous system lymphoma (PCNSL) is a rare brain tumor that most commonly arises in the cerebral white matter, basal ganglia, peri-ventricle or corpus callosum. Confinement of PCNSL to the third ventricle is extremely rare, and seldom presents with intratumoral hemorrhage (ITH). The present study described the case of a 75-year-old woman who presented with obstructive hydrocephalus due to third-ventricle PCNSL. On magnetic resonance imaging (MRI), the tumor presented ITH on T2*-weighted images and a highly elevated regional cerebral blood volume on dynamic susceptibility contrast-enhanced MRI (DSC-MRI). Due to the high elevation of the regional cerebral blood volume, high-grade glioma was suspected as a preoperative diagnosis. The patient underwent endoscopic tumor biopsy and third ventricle PCNSL was successfully diagnosed. The patient achieved good prognosis at an early stage after the start of treatment initiation. There are many differential considerations for a third-ventricle tumor, and DSC-MRI can help the differential diagnosis of these tumors. Furthermore, the presence of ITH can lead to the inaccurate estimation of regional cerebral blood volume values. Overall, silent or microhemorrhage in PCNSL may be underestimated, and clinicians should therefore carefully evaluate tumor vascularity by MRI.

[A Case of Bilateral Medial Medullary Infarction With Heart Appearance Sign].

We report a bilateral medial medullary infarction in which diffusion-weighted images revealed a unique configuration: a heart appearance sign. If it is early diagnosed, it might predict a poor outcome. An 85-year-old man developed dysarthria and numbness in his four limbs and was transferred to our hospital. Brain MR diffusion-weighted images revealed a high-intensity lesion in the bilateral medial medulla oblongata -- a heart appearance sign -- and we diagnosed a bilateral medial medullary infarction. Although his symptom changed aggressively for the worse, it finally changed for the better without bulbar paralysis, and he was transferred to another hospital for rehabilitation. When the medial medulla oblongata is supplied by the unilateral control of the anterior spinal artery, its occlusion can cause a bilateral medial medullary infarction.

[A Case of Hearing Loss Preceding Anterior Inferior Cerebellar Artery Infarction Syndrome With a Progressive Course].

Anterior inferior cerebellar artery (AICA) syndrome is a well-known symptomatic disorder. AICA syndrome is one of the causes of sudden hearing loss seen in recent years, but most of these cases were diagnosed as hearing loss preceded by other symptoms. Due to variations in AICA, we consider that many cases are actually not recognized as AICA syndrome. In this report, we describe a case of AICA syndrome preceded by hearing loss and describe its course of progression.

Molecular Genetic Profile of 300 Japanese Patients with Diffuse Gliomas Using a Glioma-tailored Gene Panel.

Rapid technological advances in molecular biology, including next-generation sequencing, have identified key genetic alterations in central nervous system (CNS) tumors. Accordingly, the fifth edition of the World Health Organization (WHO) CNS tumor classification was published in 2021. We analyzed 303 patients with diffuse glioma using an amplicon-based glioma-tailored gene panel for detecting 1p/19q codeletion and driver gene mutations such as IDH1/2, TERTp, EGFR, and CDKN2A/B on a single platform. Within glioblastomas (GBMs), the most commonly mutated genes were TERTp, TP53, PTEN, NF1, and PDGFRA, which was the most frequently mutated tyrosine kinase receptor in GBM, followed by EGFR. The genes that most commonly showed evidence of loss were PTEN, CDKN2A/B, and RB1, whereas the genes that most commonly showed evidence of gain/amplification were EGFR, PDGFRA, and CDK4. In 22 grade III oligodendroglial tumors, 3 (14%) patients had CDKN2A/B homozygous deletion, and 4 (18%) patients had ARID1A mutation. In grade III oligodendroglial tumors, an ARID1A mutation was associated with worse progression-free survival. Reclassification based on the WHO 2021 classification resulted in 62.5% of grade II/III isocitrate dehydrogenase (IDH) -wildtype astrocytomas being classified as IDH-wildtype GBM and 37.5% as not elsewhere classified. In summary, our glioma-tailored gene panel was applicable for molecular diagnosis in the WHO 2021 classification. In addition, we successfully reclassified the 303 diffuse glioma cases based on the WHO 2021 classification and clarified the genetic profile of diffuse gliomas in the Japanese population.

Atypical and Fibrous Meningioma with Differential Cerebral Blood Volume on Magnetic Resonance Imaging: A Case Report.

Magnetic resonance imaging (MRI) features of meningiomas typically reveal a well-circumscribed and contrast-enhancing dural mass. Here we discuss the differences in MRI findings between typically benign and atypical meningioma, and their clinical implications. An MRI of a 67-year-old man revealed a substantial homogeneous enhancing tumor nodule. The MRI also showed two components in the tumor, and the regional cerebral blood volume (rCBV) was higher in the lateral than in the medial mass. A pathological examination also revealed features of both benign and atypical meningiomas. The Ki-67 labeling index was 1% on the medial side and 5% on the lateral side. There were clearly two components within the tumor mass, and the MRI revealed differential rCBV in the tumor. The results indicated a nontypical MRI of meningiomas, allowing for predictability of atypical meningiomas using MRI before surgical resection.

[Duplication of Basilar Artery - A Case Report].

We report a duplication of basilar artery, it is a rare variation of vessel and arisen from unfusing of a posterior longitudinal neural arteries. 71-year-old man with hypertension, was referred to our hospital for a visual disturbance. The duplication of basilar artery was incidentally discovered on a magnetic resonance imaging (MRI). MRI showed an artery lined up side by side a basilar artery in front of brain stem, it was connected from vertebral artery to anterior inferior cerebellar artery. So it was diagnosed a duplication of basilar artery. A duplication of basilar artery is not a rare variation of vessel but a comparatively few variation of vessel, because some cases of the fenestration of basilar artery were included the duplication of basilar artery on review of the literature. And it occurred to be stabilized its back flow.

Surgical management of primary Ewing's sarcoma of the petroclival bone extend into the sphenoid sinus: A case report and review of literatures.

BACKGROUND: Ewing's sarcoma (ES) is a malignancy that arises from bones or soft tissue, characterized by primitive small and round blue cells. Primary ES typically occurs in the long bones, vertebrae, or pelvis, and is extremely rare in the skull base. CASE DESCRIPTION: A 14-year-old girl presented with posterior cervical pain and dysfunction of multiple cranial nerves (CNs). Radiological investigation revealed a solid mass of the petroclival bone extending into the sphenoid sinus. The patient underwent endoscopic transsphenoidal surgery for diagnosis of the pathology, and partial resection was safely achieved. Histopathological, genetic, and radiological examinations confirmed the diagnosis of primary ES. Subsequently, the patient underwent adjuvant chemotherapy and radiotherapy following which the clinical symptoms resolved. Complete response was achieved after multimodal treatment. Twenty months after treatment, the patient remains in remission without recurrence or metastatic disease. Primary ES of the petroclival bone has been reported in only three cases in the literature. As seen in the present case, dysfunction of multiple CNs is the most common manifestation of petroclival ES. Diagnosis should be confirmed by histopathological and genetic examinations considering the nonspecific clinical symptoms and radiological features. CONCLUSION: Multimodal treatment, including surgery, chemotherapy, and radiotherapy, can result in favorable outcomes. Clinicians should consider safe resection during surgical management to prevent complications that can delay postoperative multimodal treatment.

[An Unruptured Extracranial Saccular Aneurysm, Arising from the Fenestrated Posterior Inferior Cerebellar Artery Originated from Extracranial Vertebral Artery: Case Report].

We present an extremely rare case of an extracranial saccular aneurysm arising from the proximal end of a distal fenestration in the posterior inferior cerebellar artery (PICA), with the PICA originating extra-cranially from the vertebral artery (VA). [Case] A 71-year-old woman with hypertension, was referred to our hospital for hearing disturbance. After the incidental discovery of an unruptured aneurysm on magnetic resonance imaging, an angiography showed the aneurysm arising from the proximal end of the right distal fenestrated PICA. Both the aneurysm and the origin of the PICA were extracranial. The patient was treated conservatively because of the size and shape of the aneurysm. [Conclusion] A literature review revealed nine reported cases of fenestrated PICAs, two of which were aneurysms with fenestrated PICAs. This present case repot is the first to describe an extracranial aneurysm in a fenestrated PICA of extracranial origin. Embryologically, PICA fenestrations may represent remnants of a plexiform arterial channel between the primitive VA and a vertebrobasilar anastomosis.