Spontaneous intracranial hypotension (SIH) is no longer considered rare. Its estimated annual incidence is 5 cases per 100,000 individuals, which is half the incidence of subarachnoid hemorrhage. Epidural blood patch (EBP) is indicated for SIH patients who do not improve with conservative treatment. Accurate determination of the cerebrospinal fluid (CSF) leak site is critical for a successfully targeted EBP. We report the case of a 43-year-old woman with SIH secondary to CSF leakage at the craniovertebral junction dural entry point of the vertebral artery (VA). We treated the patient 2 months after the onset of symptoms. Fat-suppressed T2-weighted spinal magnetic resonance (MR) images revealed a massive epidural fluid collection around the upper thoracic spine. Extravasation of contrast medium through the left VA-dural entry point was clearly visible on computed tomographic myelography. A cervical EBP was injected through the C1-2 interlaminar space. The patient had a smooth recovery and was asymptomatic, with normal spinal MR findings, 6 months after treatment. The possibility of CSF leakage from the dural entry point of the VA should be considered in SIH patients. EBP targeted at the VA entry point is proposed as a safe and effective treatment.

Aplastic or twig-like middle cerebral artery (Ap/T-MCA) is a rare vascular anomaly that can cause a hemorrhagic or ischemic event. We report a 38-year-old man who presented with intracerebral hemorrhage from a ruptured aneurysm associated with an Ap/T-MCA. After aneurysm trapping and resection, histopathological examination revealed an internal elastic lamina (IEL) disruption and a thin aneurysmal wall. The patient recovered well after surgery and rehabilitation. No hemorrhagic or ischemic events have occurred during 2 years of follow-up. Ap/T-MCA-associated aneurysms exhibit a disrupted IEL and thin wall, which demonstrates the fragility of the "twig-like" vessels.

It has been reported that bevacizumab, an agent administered as an adjuvant therapy for high-grade gliomas, causes thromboembolic complications. We report a cerebral infarction with newly developed cerebral artery stenosis occurring during treatment with bevacizumab for an anaplastic astrocytoma. A 48-year-old female underwent excision surgery for an anaplastic astrocytoma on the right temporal lobe and received radiation therapy and chemotherapy with temozolomide. Twenty months after the maintenance therapy, treatment with bevacizumab was introduced for tumor recurrence. After the 14th course of bevacizumab at 6 months, 27 months after radiation therapy, the patient began experiencing mild right hemiparesis. Magnetic resonance imaging revealed scattered cerebral infarcts on the left frontal lobe and diffuse cerebral artery stenosis of the bilateral internal carotid artery system both inside and outside the radiation-treated area. Antiplatelet medication was commenced, and there was no recurrence of ischemic stroke. The morphological transition of the cerebral arteries should be carefully monitored via magnetic resonance angiography during post-radiation treatment with bevacizumab.

Septum pellucidum cyst is rare and is defined as a fluid-filled space between the lateral ventricles; it has a width of 10 mm or more. In this case report, a surgical patient of symptomatic septum pellucidum cyst (SPC) in extreme age is described. To the best our knowledge, this is the first report of an extremely aged patient with symptomatic SPC that was successfully treated using a flexible neuroendoscope. An 85-year-old male complained of gradually worsening gait disturbance, dementia, and urinary incontinence without headache and was admitted to our hospital. MRI revealed a huge cyst between the lateral ventricles as well as ventricle dilatation with periventricular hyperintensity in T2-weighted image. The patient was diagnosed with symptomatic hydrocephalus with SPC and underwent neuroendoscopic fenestration of the cyst with the use of a flexible endoscope without cerebrospinal fluid shunt placement. Immediately after the surgery, the patient's gait disturbance and dementia were dramatically improved. In extremely aged patients, SPC tended to develop with idiopathic normal pressure hydrocephalus-like symptoms, including gait disturbance without increasing intracranial pressure, sensorimotor disturbances, and psychological disorders. Neuroendoscopic cyst fenestration with the use of a flexible scope for SPC is a less-invasive procedure and should be considered even for extreme elderly symptomatic patients.

A 36-year-old woman presented with sudden onset of a right-sided headache that awoke her from sleep. She had no episodes of trauma or abuse. She was initially able to speak, but fell into a coma within an hour. The right pupil was dilated, with slow pupillary reflexes to light on both sides, and she showed left hemiparalysis. Computed tomography scan showed a right acute epidural hematoma, approximately 4 cm in thickness, and there were no findings of trauma such as skin wounds, subcutaneous hematomas, or skull fractures. In the emergency room, decompression of intracranial pressure by one burr hole was performed, and her dilated right pupil improved to normal size. She was then moved to the operating room, and hematoma removal was performed by craniotomy. Her blood pressure trended downward despite rapid blood transfusion and vasopressor therapy. There were no abnormal findings apparent intraoperatively, except for oozing from the whole surface of the dura mater and epidural space. Her consciousness improved postoperatively, and her left hemiparalysis improved within a few days. No causative diseases, risk factors, or vascular abnormalities were found on laboratory and radiological surveys. Two months postoperatively, the bone flap was removed because of infection. Eight months postoperatively, a cranioplasty using artificial skull was performed, and her postoperative course was uneventful. One year after the initial surgery, she has no neurological deficits, and there has been no recurrence of epidural hematoma.

Because of nonspecific clinical and radiological findings, it is difficult to diagnose isolated neurosarcoidosis without histological examination. Distinguishing neurosarcoidosis from neoplasm, infectious disease, or granulomatous disease can be challenging.In this study, we present a case of a 61-year-old female who presented with unilateral blindness. Magnetic resonance imaging (MRI) revealed a large invasive mass lesion located in the neurohypophysis with homogeneous enhancement after the injection of gadolinium. The lesion involved the bilateral cavernous sinus, which extended along the dura of the skull base with leptomeningeal lesions. Contrast-enhanced computed tomography (CT) and fluorodeoxyglucose positron emission tomography/CT of the entire body showed no other lesions. Biochemical examinations showed no useful data, including angiotensin-converting enzyme, β-glucan, soluble interleukin-2 receptor, and T-SPOT. Cerebrospinal fluid examination revealed only the elevation of total protein. Under the preoperative diagnosis of a malignant tumor or metastatic tumor, followed by tuberculosis, fungal infection, or granulomatous disease, a biopsy was performed to immediately determine the appropriate therapy, which revealed the histological diagnosis of sarcoidosis. After steroid therapy, the lesions had markedly shrunk as observed on MRI, and the eyesight of the patient's right eye was completely restored. In this case, without a biopsy, discriminating between sarcoidosis and a malignant tumor was difficult. We believe that a prompt histological diagnosis of an invasive isolated neurohypophysial mass lesion involving the bilateral cavernous sinus, which is similar to a malignant tumor, is essential for selecting the appropriate therapy.

Stent-assisted coil embolization (SACE) is useful for treating wide-necked aneurysms. Most superior cerebellar artery (SCA) aneurysms have a wide neck, but there are few reports of SCA aneurysms treated with SACE.

One reason is that the anatomical characteristic of SCA aneurysm is not suitable for standard SACE. It is often challenging to deliver a stent to SCA via the basilar artery in an anterograde manner. In contrast, it is not difficult to deliver a stent to SCA from the anterior circulation via the posterior communicating artery. This method, in which a catheter is navigated from the anterior to the posterior circulation, is called a transcirculation technique.

We report two cases of SCA aneurysm successfully treated with SACE using transcirculation technique. This approach is helpful for wide-necked SCA aneurysms.

Hemorrhagic isolated dural arteriovenous fistulas (DAVFs) are often challenging to treat. Here, we report a case of the lateral cavernous sinus (CS) DAVF successfully treated by transarterial intravenous coil embolization using a curved multiplanar reconstruction (MPR) image assistance. A 54-year-old man presented with a severe headache and was diagnosed with subarachnoid hemorrhage caused by CSDAVF. Angiography indicated that the fistula was fed by branches of the left external carotid artery and drained into cortical veins. There were multiple shunting points at the left sphenobasal vein accompanied by varicose veins. Using curved MPR images, the left accessory meningeal artery was chosen for the endovascular approach into the affected veins, including ruptured varix. The shunt was completely occluded by detachable coils.

When the curved MPR image indicates a developing feeding artery and a large shunting point, transarterial intravenous coil embolization becomes a good treatment option for CSDAVF, which has no venous access.

Internal carotid artery occlusion rarely recanalizes spontaneously. Awareness of signs of recanalization is important, as it may necessitate changing the treatment strategy. We report a case of new cortical infarction outside the border zone, which led to the realization of internal carotid artery recanalization and revascularization.

A 76-year-old woman presented with mild dysarthria. Magnetic resonance imaging showed cerebral infarction in the left-hemispheric border zone and occlusion of the internal carotid artery origin. Cerebral angiography performed showed complete occlusion of the internal carotid artery origin and intracranial collateral blood flow from the external carotid artery through the ophthalmic artery. She was diagnosed with infarction due to a hemodynamic mechanism caused by internal carotid artery occlusion and was treated with supplemental fluids and antithrombotic drugs. Four days after hospitalization, the right paralysis worsened and a new cerebral infarction was observed in the cortex, outside the border zone. This infarction appeared to be embolic rather than hemodynamic; thus, we suspected recanalization of the internal carotid artery. The patient underwent emergency cerebral angiography again, which revealed slight recanalization. Thus, emergency revascularization and carotid artery stenting were performed. New cortical infarcts outside the border zone in patients with complete internal carotid artery occlusion is an important finding, suggesting spontaneous recanalization of the occluded internal carotid artery.

We report the use of endoscopic endonasal surgery for dural reconstruction following a cerebrospinal fluid leak in a 33-year-old patient with recurrent meningitis since at age of 2 years. Magnetic resonance imaging showed osteolytic changes in the left temporal and sphenoid bones, including the left pterygoid plate, a few left temporal encephaloceles, and cerebrospinal fluid-like fluid in the expanded Meckel's cave and the parapharyngeal space. After endoscopic endonasal surgery, Gorham-Stout disease was diagnosed. No recurrence of cerebrospinal fluid leakage or meningitis has been observed. Thus, endoscopic endonasal surgery might improve clinical outcomes in patients with Gorham-Stout disease and skull base defects.

Coronavirus disease 2019 (COVID-19) -related intracranial hemorrhage (ICH) is believed to be associated with at least one known risk factor for ICH, such as hypertension, hyperlipidemia, diabetes mellitus, severe pneumonia, or anticoagulation therapy. However, in this study, we report a case of ICH in a 14-year-old boy with mild COVID-19 infection without pneumonia who had no such risk factors. The only abnormal laboratory finding was temporary depletion of vitamin K-dependent coagulation factors. This case indicates that COVID-19 infection may cause simultaneous asymptomatic intracranial microhemorrhages and temporary depletion of vitamin K-dependent coagulation factors. This temporary depletion might transform the intracranial microhemorrhages into symptomatic ICH.

Posterior inferior cerebellar artery (PICA) variations are well recognized; however, their mechanisms have not been well understood. Primitive lateral basilovertebral anastomosis (PLBA) was described in 1948 by Padget and is one of the embryological transient longitudinal channels in the hindbrain. This study reports a PICA aneurysm associated with PLBA. A 48-year-old man presented with subarachnoid hemorrhage. Cerebral angiography showed a 3.6-mm fusiform aneurysm with a bleb of the left PICA just at the origin of the PICA from the vertebral artery. Furthermore, a direct anterior inferior cerebellar artery (AICA) -PICA anastomosis parallel to the basilar artery was revealed. This direct anastomosis between the AICA and PICA is explained by the partial persistence of PLBA. Variations in the three cerebellar arteries and vertebrobasilar junction can be caused by persistence of PLBA.

There are various causes of ventriculoperitoneal shunt (VPS) failures. Patients who receive shunt placement during childhood need follow-up for decades as they grow, especially in the early periods of life. Herein, we report a rare case of mechanical shunt obstruction in a pediatric patient in whom a cramped burr hole and skull growth compressed the tube and obstructed cerebrospinal fluid flow. A 6-year-old girl presented to our hospital with nausea and headache. She was born preterm and developed intraventricular hemorrhage followed by VPS placement for hydrocephalus; thereafter, she had no need for shunt revision until this admission. After careful evaluation of the patency of the shunt system, the presence of tube stenosis was suspected at the site of the shunt tube penetrating the burr hole of the skull. During the operation to revise the shunt tube, a compressed tube was observed at the exit from the skull. After enlarging the narrowed burr hole and reconstructing the proximal catheter, her symptoms immediately improved. Previously, only one case of shunt malfunction due to tube compression from bone growth has been reported in a pediatric patient with osteopetrosis. To the best of our knowledge, such a condition has never been described in pediatric patients with no metabolic bone disease. Although it is rare, obstruction at the exit from the skull due to bone growth should be included in differential diagnoses for young patients during a long follow-up after VPS.

Here we report a rare case of capillary hemangioma (CH) in a 28-year-old woman suffering from gradual worsening diplopia at 28 weeks of pregnancy. Magnetic resonance imaging (MRI) showed a mass lesion (about 3 cm in diameter) in the right parasellar region. We decided to observe as she was pregnant, and had no symptoms other than right abducent nerve palsy. Fortunately, her symptoms did not worsen until delivery. Computed tomography, enhanced MRI, and angiography after delivery revealed that the lesion was highly calcified and vascularized. A dorsum sellae meningioma or highly calcified pituitary adenoma was suspected and the endoscopic transsphenoidal approach was used for tumor removal.

The postoperative course was uneventful. The histological diagnosis was CH.

Intracranial CHs or CHs of skull are rare vascular tumors. These tumors are reportedly more common in female patients and may change in size in adults according to menstrual cycle and pregnancy. Only six cases, including that of the present study, were diagnosed during the perinatal period. Some of them experienced rapid symptom progression and tumor growth in their course; thus, we should pay further attention to pregnant or peripartum patients with brain tumor, suspected hemangiomas.

Lymphomatosis cerebri is an atypical form of primary central nervous system lymphoma (PCNSL), which frequently causes rapid progression of dementia. A 68-year-old woman exhibited rapidly progressing disorientation and a mini-mental state examination score of 9. The fluid-attenuated inversion recovery of a magnetic resonance image (MRI) demonstrated focal areas of high-signal intensity in the right frontal lobe with a small enhancement, which was histologically diagnosed as diffuse large B-cell type lymphoma. The lesion dramatically shrank, and no enhancements were identified on MRI after treatment with high-dose methotrexate (MTX) and whole-brain radiation (WBR). However, her recovery of cognitive function was poor. The patient visited our clinic every 2 months but succumbed to systemic mycotic sepsis 14 months after the biopsy. Autopsy revealed lymphomatosis cerebri in the patient based on a feature of scattered small clusters of lymphoma cells infiltrating into the brain parenchyma in both cerebral hemispheres. Differentiation of lymphomatosis cerebri from other white matter degenerative diseases is usually challenging because lymphomatosis cerebri seldom forms mass lesions. In lymphomatosis cerebri, the lymphoma cells infiltrate into several regions in the brain tissue, including the basal ganglia, brainstem, and corpus callosum, in addition to periventricular and subcortical white matters. The rapid deterioration of cognitive function in the patient suggests a rapid spread of lymphomatosis cerebri, necessitating early histological diagnosis and prompt treatments. If the diagnosis is obtained, administration of high-dose MTX and WBR followed by rituximab and cytarabine can contribute to a longer survival time, based on our literature review.

A dysembryoplastic neuroepithelial tumor (DNT) is a benign neoplasm that usually occurs in the supratentorial cerebral cortex. Here, we report a rare case of an infratentorial DNT in a 42-year-old woman who presented with dizziness and a gait disturbance. Magnetic resonance imaging of the lesion demonstrated hyperintensity on T2-weighted images and hypointensity on T1-weighted images of the left cerebellar hemisphere with a multifocal lesion. Macroscopically, the lesion appeared soft, avascular, and slightly torose at the cortical surface. Histologically, dysplastic disorganization of the cortex and floating neurons were observed. The pathological and immunochemical features of this case agree with the diagnosis of a DNT. The lesion partially included cortical heterotopia, which is a novel observation in an infratentorial DNT. On the basis of the previous reports, we discussed the surgical resection of the infratentorial DNT.

The coronavirus disease 2019 (COVID-19) pandemic continues to spread around the world, and widespread vaccination is considered the most effective way to end it. Although the efficacy of COVID-19 vaccines has been confirmed, their safety remains a concern. In this paper, we report two cases of ruptured vertebral artery dissecting aneurysm (VADA) immediately after messenger RNA (mRNA) anti-COVID-19 vaccination. In Case 1, a 60-year-old woman experienced sudden headache 3 weeks before her first dose of the Moderna mRNA-1273 COVID-19 vaccine. Magnetic resonance imaging showed dilatation of the right vertebral artery (VA) without intracranial hemorrhage. A day after the vaccination, she developed subarachnoid hemorrhage with pulmonary effusion due to a ruptured right VADA. She underwent endovascular internal trapping and parent artery occlusion under general anesthesia. In Case 2, a 72-year-old woman with a previous history of the left VA occlusion due to arterial dissection developed subarachnoid hemorrhage 7 days after the first dose of the Pfizer-BioNTech BNT162b2 COVID-19 mRNA vaccine due to a ruptured right VADA and underwent stent-assisted coil embolization under general anesthesia. The postoperative courses of these two cases were uneventful. The accumulation of more cases and further study are warranted to clarify the relationship between COVID-19 mRNA vaccination and ruptured intracranial dissecting aneurysms.

Intracranial myxoid mesenchymal tumors (IMMTs) with EWSR1-CREB1 family gene fusion are rare brain neoplasms characterized by gene fusion between the EWSR1 gene and one of the cyclic AMP response element-binding (CREB) family transcription factor (CREB1, ATF1, or CREM) genes. Although half of reported cases are pediatric, the clinical, histologic, and genomic features of IMMTs with EWSR1 rearrangement in pediatric populations are not yet well clarified. Here we describe the case of a 7-year-old girl who presented with seizures due to an extra-axial tumor in the left parietal convexity. Gross total resection was achieved, and the tumor displayed a multilobular structure with solid hypercellular and myxoid hypocellular areas, separated by a variable amount of stroma. The hypercellular areas consisted of round to polygonal cells, whereas the myxoid areas were ovoid to spindled cells. Immunophenotypically, the tumor cells were positive for vimentin, desmin, and EMA. Next-generation sequencing of tumoral DNA revealed EWSR1-CREM gene fusion and a pathogenic mutation of MAP3K13. No recurrence was detected 9 months after resection, without chemotherapy or radiotherapy. In comparison to other pediatric and adult patients with EWSR1 rearrangement, many clinical, radiological, and immunohistochemical features were shared. However, signs of elevated intracranial pressure were more frequently observed, and postoperative radiation was less frequently administered for pediatric patients. Gross total resection (GTR) was the key prognostic factor for better disease control especially among pediatric patients. Further reports of cases with EWSR1 rearrangement with detailed genetic profiles are essential for clarifying the oncogenic pathway and establishing a standard treatment strategy.

Chronic encapsulated intracerebral hematoma (CEIH) is a rare cerebrovascular disease featuring progressively expanding intracranial hematoma. We treated a man in his 70s with bilateral cerebellar CEIH. He had presented at another hospital with dizziness, and imaging showed two independent hemorrhagic space-occupying lesions in the bilateral cerebellar hemispheres. The symptoms progressed relatively rapidly, and there were signs of impending cerebellar herniation; he was transferred to our institution, and emergency surgery was performed. The operative findings included a hematoma with partial capsulation. We diagnosed CEIH from preoperative magnetic resonance imaging and computed tomography findings, clinical course, and pathological findings. The postoperative course was satisfactory. We present this case of bilateral cerebellar CEIH, as an extensive search of the literature suggests that this has not been reported before. Although CEIH is a condition that is usually hard to diagnose preoperatively, good outcomes can be achieved with appropriate surgical treatment. It is therefore important to keep this clinical entity in mind and not miss the right timing to operate.

Epistaxis due to rupture of a nontraumatic internal carotid artery (ICA) aneurysm in the paranasal sinus has rarely been reported. Here, we report a case of double ICA aneurysms located within both the sphenoid and ethmoid sinuses. A 78-year-old woman presented with recurrent massive epistaxis. Magnetic resonance angiogram (MRA) and cerebral angiogram showed two ICA aneurysms: one protruded into the sphenoid sinus and the other protruded into the ethmoid sinus. Intra-aneurysmal coil embolization was performed for both aneurysms. The patient recovered completely, and a follow-up MRA 3 years later showed no recurrence of the aneurysms. Intra-aneurysmal coil embolization is an option of treatment for an ICA aneurysm filling the paranasal sinus.

An 85-year-old woman presented with ataxia and deterioration of cognitive functions. She had no history of autoimmune diseases or viral infections. Magnetic resonance imaging showed a solitary mass lesion at the cerebral falx on contrast-enhanced T1-weighted imaging. Gross total resection of the lesion involving the dura mater was performed by bifrontal craniotomy. Histological examination showed diffuse infiltration of small lymphocytes and plasma cells. There was also some proliferation of large lymphocytes with folded nuclei, high-density chromatin, and inconspicuous nucleoli. The large atypical B lymphocytes did not demonstrate diffuse dense sheet findings. Meningothelial components were not detected. Immunohistochemistry was positive for pan B-cell antigens. The analysis of the kappa/lambda ratio indicated kappa immunoglobulin light chain-restricted B-cell proliferation. The final histopathological diagnosis was mucosa-associated lymphoid tissue lymphoma. Systemic screening examinations were then performed. Histological findings of the bone marrow showed normal findings without atypical lymphocytes. A chromosomal study of the bone marrow showed 46, XX. 18F fluoro-2-deoxyglucose positron emission tomography showed high accumulations at the left pterygoid muscle and the right transverse processes of the thoracic vertebrae, and mild accumulation at the right ilium bone, which indicated disseminated lesions. One year later, thickening of the dura mater was detected. Therefore, gamma knife surgery was performed. Two years later, she was alive without neurological deterioration, and magnetic resonance imaging showed no evidence of recurrence.

Posterior inferior cerebellar artery (PICA) aneurysms often require cerebral vascular reconstruction for surgical treatment because of their characteristic morphology. Despite its potential complications, the occipital artery-to-posterior inferior cerebellar artery (OA-PICA) bypass is a typical treatment because of its versatility. Although a few cases of intracranial-to-intracranial bypass have been reported, this type of vascular reconstruction is only regarded as an alternative to the OA-PICA bypass because of the uncertainty of bypass feasibility and potential risk of ischemic complications. In this article, we report a case of proximal PICA ruptured aneurysm that was treated with a PICA-to-PICA (PICA-PICA) bypass. A 79-year-old man presented with a chief complaint of sudden, severe headache and disturbances in consciousness. Radiological examination revealed a right proximal PICA fusiform aneurysm. The patient had many systemic disorders such as microscopic polyangiitis and steroid-induced diabetes mellitus that could have caused wound dehiscence and cerebrospinal fluid (CSF) leakage. We performed the PICA-PICA bypass and trapping surgery rather than the OA-PICA bypass to avoid skin problems and CSF leakage. The postoperative course was uneventful, and the patient was discharged on day 64 without any neurological disorders. In comparison with the OA-PICA bypass, the PICA-PICA bypass is less likely to cause CSF leakage and skin complications, although it carries the risk of specific ischemic complications and requires advanced surgical techniques. For some patients with systemic disorders, the PICA-PICA bypass could be an optimal treatment option for proximal fusiform PICA aneurysms rather than as an alternative to the OA-PICA bypass.

An 85-year-old man underwent emergency right trepanation and drainage for a symptomatic chronic subdural hematoma. Pseudohypoxic brain swelling (PHBS) was suspected because magnetic resonance imaging revealed diffuse brain swelling. Although cerebrospinal fluid (CSF) leakage was not obvious during or after surgery, most of the reported PHBS cases have leaked CSF during craniotomy or spine surgery. PHBS has not been previously reported in patients without obvious CSF leakage or after unilateral burr hole drainage. Herein, we report an extremely rare case with a literature review investigating its pathogenesis and clinical features.

Stenotic developmental venous anomalies (DVAs) often present with neurological deficits. In addition, cerebral capillary telangiectasia (CCT) coexisting with DVA is rarely encountered, and its pathophysiology, including the underlying genetics, and appropriate management remain uncertain. A 46-year-old man without any medical history of note was referred to our hospital with gradually worsening cerebellar ataxia. Two months after symptom onset, ataxic dysarthria and gait emerged. Brain magnetic resonance imaging showed CCT occupying the pons and left cerebellar peduncle. Subsequent catheter angiography demonstrated a DVA leading from the mass into the cavernous sinus with marked outlet stenosis and flow stagnation. We hypothesized that venous congestion was the source of gradual neurological deterioration and therefore initiated anticoagulation. Symptoms showed mild improvement, and his neurological status has remained stable as of 1 year after symptom onset. Whole-exome sequencing of germline DNA did not reveal any rare variants in genes previously reported as pertinent to vascular malformations. Anticoagulation may be a useful option in patients with non-thrombotic, stenotic DVA for whom neurological status did not improve under expectant management. Genetic analysis of this patient did not reveal any pathogenic mutations, and further investigation of somatic mutations is necessary to elucidate potential genetic causes.

Various COVID-19 vaccines are associated with numerous adverse side effects. Associations between vaccinations and neurological disorders, such as transverse myelitis, stroke, Bell's palsy, acute disseminated encephalomyelitis, and Guillain-Barré syndrome, have been reported. A 27-year-old Japanese woman presented with paresthesia four days after receiving a second dose of the COVID-19 vaccine. One month after vaccination, she started to feel left lower limb weakness, and her symptoms almost improved after two steroid pulse therapies. Spinal cord tumor biopsy could potentially help make a definitive diagnosis in clinical situations. However, it is very important to review the patient's medical history, including vaccinations received, before performing a direct spinal cord biopsy, which is invasive and does not guarantee a definitive diagnosis.

Endovascular embolization of the middle meningeal artery (MMA) has been reported as an effective method for treating chronic subdural hematoma (CSDH); however, its preventive effect on CSDH following craniotomy is unknown. We present a case in which MMA embolization was ineffective in preventing CSDH following craniotomy. A 56-year-old man who complained of diplopia was diagnosed with sphenoid ridge meningioma with a 3-cm diameter. MMA embolization prior to the operation and total surgical removal of the tumor were performed. Two months postoperatively, the patient complained of headache and hemiparesis of the left side. CSDH with a 15-mm thickness and a midline shift was observed. MMA embolization before inflammation may not play a role in preventing CSDH development because MMA embolization is considered effective in CSDH because it is associated with the blood supply of neovessels that are newly formed due to inflammation. Therefore, MMA embolization might not be effective in preventing the occurrence of CSDH following craniotomy.

Penetrating neck injury by a crossbow bolt is extremely rare and can be life-threatening. When removing a crossbow bolt from the neck, it is necessary to protect against fatal bleeding from the carotid vessels. We report removing a crossbow bolt penetrating the neck, with an endovascular approach. A 49-year-old woman was shot in the neck by a crossbow and was transferred to our hospital. On presentation, the crossbow bolt totally penetrated the neck from right to left. Her level of consciousness was clear, with no significant neurological deficits except for right peripheral facial palsy. Neck contrast-enhanced computed tomography revealed the crossbow bolt in contact with bilateral external and internal carotid arteries and that the bolt caused dissection of the left main trunk of the external carotid artery. Under general anesthesia, the crossbow bolt was removed under fluoroscopy with the assistance of an endovascular approach. First, we performed coil embolization for the dissected external carotid artery. Second, we prepared for fatal bleeding from the carotid arteries during crossbow bolt removal under protection using guiding catheters placed in bilateral common carotid arteries. The bolt was removed successfully without significant bleeding, and no complications occurred during the procedure. We report the successful removal of a crossbow bolt penetrating the neck. When removing a crossbow bolt penetrating the neck, endovascular assistance may be feasible to protect against fatal bleeding from the carotid arteries.

Chronic subdural hematoma (CSDH) typically develops in the supratentorial region in elderly patients. We treated a case of unilateral supratentorial and bilateral infratentorial CSDH, whereby the patient had a coronavirus disease 2019 (COVID-19) infection combined with disseminated intravascular coagulation 2 months earlier. The patient had not experienced any head trauma before the onset of the CSDH. The postoperative course was uneventful, and the patient experienced no neurological deficit. We propose that we should be aware not only of acute ischemic or hemorrhagic diseases after COVID-19 infection but also of chronic subdural hematoma caused by coagulopathy after a COVID-19 infection.

We report a rare case of hypoglossal canal meningioma in a 65-year-old woman who presented with dysphagia. Neurological examination revealed left hypoglossal nerve palsy. Head computed tomography and magnetic resonance imaging revealed a lesion around the left hypoglossal canal. She underwent a total resection with a midline suboccipital transcondylar approach. There were no postoperative complications, and the hypoglossal nerve palsy improved. There was no recurrence nine months after the surgery. Choosing a surgical approach that considers the site of origin and extent of tumor extension is important.

Gelatin-based hemostatic agents are widely used in neurosurgery. This is a case of postoperative aphagia strongly suspected to be caused by an allergic reaction to a gelatin-based hemostatic agent after anterior cervical decompression and fusion for central cervical cord injury. A 55-year-old man underwent cervical anterior decompression and fusion at the C3/4 and 4/5 levels for central cervical cord injury. Immediately after the surgery, he could not swallow saliva at all, but his voice was not hoarse. Postoperative cervical computed tomography and magnetic resonance imaging showed significant edema from the post-hypopharynx wall to the front of the vertebral body. The retropharyngeal space was remarkably enlarged to 15.8 mm with cervical spine X-rays. Without neurological symptom improvement, his condition was diagnosed as marked edema of the area where Surgiflo (porcine-derived gelatin-based hemostatic agent; Johnson & Johnson Wound Management, Somerville, NJ, USA) had been applied during the operation. It was strongly suspected to be caused by an allergic response to the porcine-derived gelatin. When methylprednisolone 1000 mg was administered for 3 days from the 5th postoperative day, swallowing became almost normal within a few hours after the initial administration, and his neurological symptoms improved. The patient left the hospital on the 12th day after the operation. Before using porcine-derived gelatin products during surgery, special consideration should be given to patients with an allergy history before surgery.

Aneurysms of the A1 segment of the anterior cerebral artery tend to develop in combination with various vascular anomalies of the A1 segment. Arterial branches that originate from the A1 segment and perfuse cortical regions are known to be rare. In this report, we describe a 48-year-old woman who presented with a ruptured aneurysm at the origin of an anomalous cortical artery arising from the A1 segment, for which microsurgical neck clipping was performed. Intraoperatively, the anomalous artery was seen to originate from the A1 segment, running into the interhemispheric fissure. An aneurysm was located at the bifurcation of the anomalous artery and the A1 segment. Postoperative angiography showed that the anomalous artery has branched into the fronto-orbital artery and the frontopolar artery and terminated as the anterior internal frontal arteries. We report a rare case of an aneurysm arising from an anomalous callosomarginal artery that arose from the A1 segment and perfused the cortical region. It is of significance to recognize that an aneurysm can develop at the origin of an anomalous artery that arises from the A1 segment.

Tufted angioma is a benign vascular tumor in which immature endothelial and pericyte cells and lymphatic vascular endothelium grow. It manifests as a flat, painful erythema that gradually expands mainly on the trunk and extremities. Although tufted angiomas can also occur in other areas of the body and may be more locally invasive, they rarely occur intracranially. A 63-year-old man underwent magnetic resonance imaging (MRI) for a brain check-up 8 years before his visit to our institute, which detected a mass lesion with surrounding cerebral edema in the left frontal lobe. The patient was followed up with annual MRI analysis, which indicated slow tumor growth and gradual development of peritumoral edema. The tumor was treated by gross-total resection. Histological analysis showed a slightly dilated microvascular core surrounded by many capillary aggregates in the brain parenchyma. Immunohistochemical findings indicated that the vascular endothelial cells were positive for CD34 and Brahma-related gene-1 and were surrounded by smooth muscle actin-positive pericytes. These findings were consistent with tufted angioma. Intracranial tufted angioma is uncommon, but it should be considered in the differential diagnosis for intracranial tumorous lesions. Long-term follow-up is necessary to unravel the natural history of the disease.

Tentorial dural arteriovenous fistula (DAVF) is an aggressive vascular lesion causing progressive neurological deficits. Venous congestive cervical edema is a rare phenomenon caused by tentorial DAVF. Obliteration of the fistula and venous drainage should be the goal of treatment. A 62-year-old man was admitted with lower limb weakness and numbness. Magnetic resonance imaging (MRI) revealed extensive edema of the upper cervical cord with signal flow void at the anterior spinal cord. Internal carotid angiography revealed a tentorial arteriovenous shunt near the superior petrosal sinus fed mainly by the tentorial artery. The petrosal vein was dilated, with the transverse pontine vein, medial medullary vein, and anterior spinal vein as the main drainage route. This suggests that venous hypertension triggered the upper cervical cord edema. MRI with gadolinium enhancement showed that the varix was located just distal to the shunt. Microsurgical obliteration of the fistula and venous drainage were achieved via a suboccipital approach. A postoperative evaluation showed the disappearance of the cervical cord edema with improved clinical symptoms. Tentorial DAVF with spinal venous drainage presents with mild and slow progression of symptoms. Differential diagnosis and definite treatment are mandatory to avoid a delayed diagnosis and irreversible symptoms.

Despite recent signs of progress in diagnostic radiology, it is quite rare that a glioblastoma (GBM) is detected asymptomatically. We describe two patients with asymptomatic nonenhancing GBMs that were not diagnosed with neoplasia at first. The patients had brain scans as medical checkups, and incidentally lesions were detected. In both cases, surgical specimens histopathologically showed no evidence of neoplasia, whereas molecular genetic findings were isocitrate dehydrogenase (IDH) -wildtype, O⁶-methylguanine-DNA methyltransferase promoter (pMGMT) unmethylated, and telomerase reverse transcriptase (TERT) promoter mutated, which matched to GBM. One patient was observed without adjuvant therapy and the tumor recurred 7 months later. Reoperation was performed, and histopathologically GBM was confirmed with the same molecular diagnosis as the first surgical specimen. Another patient was carefully observed, and chemoradiotherapy was begun 6 months after the operation following the extension of the lesion. Eventually, because of disease progression, both patients deceased. We postulate that in each case, the tumor was not lower-grade glioma but corresponded to the early growth phase of GBM cells. Thus far, cases of malignant transformation from lower-grade glioma or asymptomatic GBM with typical histologic features are reported. Nevertheless, to the best of our knowledge, no such case of nonenhancing, nonhistologically confirmed GBM was reported. We conjecture these cases shed light on the yet unknown natural history of GBM. GBM can take the form of radiological nonenhancing and histological nonneoplastic fashion before typical morphology. Molecular genetic analysis can diagnose atypical preceding GBM, and we recommend early surgical removal and adjuvant treatment.

The causes of spinal epidural hematoma (SEH) have been attributed to coagulopathy, trauma, vascular anomalies, and so forth. The incidence of vascular anomalies shown by digital subtraction angiography has been reported to be 15%, and most cases have been reported to be spinal epidural arteriovenous fistulae. SEH has rarely been caused by venous congestion. We report a case of SEH in a 78-year-old male who presented to our emergency department with sudden-onset back pain, followed by complete paraplegia with bladder and rectal disturbance. Magnetic resonance imaging revealed a dorsally placed extradural hematoma extending from T10 to L1. An urgent laminectomy from T11 to L2 was performed. Computed tomography angiography (CTA) performed 1 week after the operation showed compression of the left renal vein between the aorta and superior mesenteric artery with dilation of the surrounding veins, including the spinal epidural venous plexus, at the same level as the hematoma. This was diagnosed as Nutcracker syndrome (NCS), which was consistent as a cause of SEH. The patient's symptoms gradually improved, and after 6 months, he regained normal strength in his lower extremities, but bladder and rectal disturbance remained and required intermittent self-catheterization. We chose conservative treatment for NCS, and SEH did not recur until the patient died of a cause unrelated to SEH or NCS. SEH could occur secondary to venous congestion including NCS. We emphasize the importance of investigating venous return to evaluate the etiology of SEH, which can be clearly visualized using CTA.

Facial nerve function improvement is a challenging goal in facial nerve schwannoma (FNS) surgery. Intraoperative continuous monitoring of evoked facial nerve electromyograms (CFN-EMGs) is performed in acoustic neuroma surgery to preserve facial nerve function. CFN-EMGs were applied in decompression surgery for FNS with severe facial paresis. A 39-year-old woman presented with a sudden onset of vertigo, left hearing disturbance, and severe left facial palsy with House-Brackmann (HB) grade 5. FNS was strongly suspected based on the patient's clinical course and magnetic resonance imaging findings, and the patient underwent surgical decompression of the internal auditory canal (IAC) to improve facial nerve function 9 weeks after onset. CFN-EMG responses suddenly improved after removing the posterior wall of the IAC and incising its dura matter. Since the patient's facial nerve paresis improved to HB grade 2 after surgery, CFN-EMGs could detect the moment of facial nerve decompression. This would be the first report to show that CFN-EMGs applied in decompression surgery for FNS could detect the effects of decompression during surgery in real-time. Thus, CFN-EMGs may be an effective monitoring method in decompression surgery for FNS.

There has been a noted increase in the incidence of intracranial aspergillosis; this is often attributed to the wider use of antibiotics, corticosteroids, and immunosuppressants. Fungal cerebral aneurysms due to aspergillosis after neurosurgery remain extremely rare; in fact, only seven cases have been reported in the literature. In this study, we present a patient with an Aspergillus aneurysm that elicited subarachnoid hemorrhage after endoscopic endonasal surgery (EES) for craniopharyngioma. A 70-year-old woman with recurrent craniopharyngioma and steroid treatment underwent uneventful EES. On the 5th postoperative day, she suffered subarachnoid hemorrhage. As per her computed tomography angiography findings, an aneurysm was detected on the left internal carotid artery (ICA). Subsequent digital subtraction angiography showed occlusion of the ICA and an irregularly shaped wall. The diagnosis was pseudoaneurysm. We then performed craniotomy to place a left high-flow bypass and to trap the pseudoaneurysm. Despite continuous intensive care, she died on the 25th postoperative day of a huge, left cerebral infarct. The final diagnosis was made at autopsy; it revealed destruction of the ICA and Aspergillus invasion of the vessel wall, confirming the presence of a true fungal aneurysm. Perioperatively, patients with potential immunosuppression must be carefully managed. Advanced age is a risk factor. As surgery via the paranasal sinuses raises the risk for aspergillosis, fungal infection must be ruled out in patients whose postoperative course is deemed concerning.

There are only a few case reports in which cholesterol crystals were found in the thrombus retrieved by mechanical thrombectomy for cryptogenic stroke, leading to a definitive diagnosis. We herein report a case of aortogenic embolic stroke diagnosed by the presence of rich cholesterol crystals in the retrieved thrombus and review the previously reported cases. A woman in her 80s was transferred as an emergency due to consciousness disturbance, right conjugate deviation, and severe left hemiparesis. Magnetic resonance imaging showed occlusion of the right middle cerebral artery (MCA) and acute infarction in the territory. The MCA was recanalized by thrombectomy using an aspiration catheter and stent retriever, and the symptoms improved. Although the physiological examination did not detect the embolic source during hospitalization, pathological examination of the thrombus revealed atheroma with numerous cholesterol crystal clefts and intermixing of fibrin. Contrast-enhanced computed tomography performed based on the pathological results showed atheromatous lesions in the aortic arch as the embolic source. As a subsequent treatment, medications of a strong statin and an antiplatelet agent were continued, and the patient had no recurrence. The finding that the retrieved thrombus is a simple atheroma containing cholesterol crystals with poor hemocytes suggests embolism due to plaque rupture. Pathological examination of the thrombus obtained by thrombectomy is one of the useful diagnostic approaches for stroke etiology and the determination of its treatment.

Subependymoma (SE) is a rare, usually asymptomatic, brain tumor predominantly affecting older adults and occurring in the fourth and lateral ventricles. We report a rare case of SE with intratumoral hemorrhage that could be removed by neuroendoscopy. The 81-year-old patient had been followed as an outpatient for 10 years due to an intraventricular tumor. It did not grow over the patient's lengthy follow-up. The patient was transferred to our hospital after he fainted near his home; at the time of admission, he had mild consciousness disturbance, and his Glasgow Coma Scale score was 10 points (E3V3M4). Computed tomography showed intratumoral hemorrhage and slight ventricular enlargement. Magnetic resonance (MR) imaging showed a 4 cm-sized tumor in the anterior horn of the right lateral ventricle. The lesion appeared as a mixed-intensity solid tumor and showed irregular enhancement with gadolinium. The patient underwent neuroendoscopic tumor resection on the 30^th day of the patient's hospital stay. A histopathological examination revealed small tumor cells with round nuclei scattered in the glial fibrillary background. Immunostaining was positive for glial fibrillary acidic protein; these findings are consistent with an SE diagnosis. The patient in this study had hypertension and used anticoagulants, risk factors for intratumoral hemorrhage. For intraventricular tumors with bleeding-particularly in older or more physically frail patients-minimally invasive neuroendoscopic surgery should be considered an option for tumor resection.

Methotrexate-associated lymphoproliferative disorder (MTX-LPD) occurs in patients with rheumatoid arthritis (RA) treated with methotrexate (MTX). MTX-LPD is typically associated with Epstein-Barr virus (EBV) infection and regresses with MTX discontinuation. On the other hand, EBV-negative MTX-LPDs are less common and are more likely to show partial or no regression after MTX discontinuation. There were no standard chemotherapeutic options for refractory MTX-LPD. We present a case of EBV-negative MTX-LPD in the central nervous system (CNS) that was successfully treated with rituximab, methotrexate, procarbazine, and vincristine (R-MPV), followed by reduced-dose whole-brain radiotherapy (rdWBRT), following the same treatment protocol as primary CNS lymphoma. A 59-year-old woman with RA treated with MTX presented with gradually developing staggered gait, memory deficit, and disorientation. Multiple lesions with heterogeneous contrast enhancement were discovered using brain magnetic resonance imaging. The patient was suspected of having MTX-LPD, but discontinuing MTX did not result in regression of the brain lesions. She underwent a biopsy from the left parietal lesion. The tissue was pathologically diagnosed as diffuse large B-cell lymphoma. Furthermore, pathological examination through EBV-encoded ribonucleic acid in situ hybridization demonstrated a lack of EBV infection. She was ultimately diagnosed with EBV-negative CNS MTX-LPD. We applied chemotherapy with R-MPV and rdWBRT. The patient achieved a complete response. In the case of CNS MTX-LPD without EBV infection, chemotherapy with R-MPV followed by rdWBRT may be considered.

Owing to recent advances in medical optical technology, a high-definition (4K) three-dimensional (3D) exoscope has been developed as an alternative tool to using conventional microscopes for microscopic surgery, and its efficacy for neurosurgery has been reported. We report a case who underwent simultaneous surgery aiming for en bloc resection of an anterior skull base malignancy with concurrent exoscopic transcranial and endoscopic endonasal approaches using a 4K 3D exoscope. The patient was a 76-year-old woman who underwent en bloc resection for an anterior skull base olfactory neuroblastoma 13 years ago. After confirming the recurrence of progressive olfactory neuroblastoma, tumor resection was again decided to be performed. As with the first procedure, surgery was performed in an en bloc manner, using both transcranial and endonasal approaches. Exoscope provided enough space above the surgical field to allow us to perform transcranial and endonasal surgeries simultaneously. Moreover, the surgeons could maintain a comfortable posture throughout the procedure, and total tumor removal was successfully achieved without any abnormal event. To our knowledge, this is the first report of the introduction of an exoscope aiming for en bloc resection of an anterior skull base malignancy while performing simultaneous surgery with both transcranial and endonasal approaches. We believe that the more cases are accumulated, the more efficacy of a 4K 3D exoscope will be elucidated.

Transforaminal full-endoscopic spine surgery (TF-FESS) is a novel minimally invasive spine surgery that requires only an 8-mm skin incision and causes minimal damage to the paravertebral muscles. To perform TF-FESS safely and efficiently, preoperative planning is quite important as the intervention requires anatomical understanding and high technical skills. Recently, three-dimensional (3D) printing has become a useful tool in various surgeries, and several studies have addressed its efficacy; however, there are no reports on the application of 3D printing to FESS. In this study, we present two cases of severe lumbar deformities for which preoperative 3D printing was useful. The 3D printing enabled the surgeons to visualize and plan the drilling of the superior articular process for a successful foraminoplasty at a low cost. The manufacturing equipment cost about USD 900 and is able to produce an actual-size model at a cost of less than USD 10 per patient. In conclusion, preoperative planning using 3D printing should be adopted to safely perform FESS.

First bite syndrome (FBS) is an extremely rare complication of carotid endarterectomy (CEA). FBS presents with unique characteristics, development of brief and intense pain in the ipsilateral parotid region at the first bite of each meal, and improvement with subsequent mastication. Here, we report two cases of FBS following CEA. Both cases had anatomical difficulty of a high carotid bifurcation and a high cervical lesion. The lingual and facial arteries (or their common arterial trunk) branched off the external carotid artery (ECA) close to a high carotid bifurcation. The operations required exposure of the ECA distal to these two branches and the distal internal carotid artery (ICA) with a wider range of dissection for clamping the vessels. Several days or weeks after CEA, the patients developed FBS, and their meal-related pain completely resolved in the ensuing weeks. Especially in patients with a high carotid bifurcation, several branches of the ECA tend to originate from the proximal portion of the ECA, similar to octopus arms. During CEA, in these patients, dissection around the ECA and its branches in a wider range is required for exposure of each vessel and placement of the cross-clamp. These procedures can lead to injury to the external carotid nerve and plexus, possibly causing FBS. Additionally, because of the close location of the superior cervical ganglion, external carotid nerves, and distal ICA, manipulation for exposure of the distal end of a high plaque can increase the risk of injury to the cervical sympathetic nerves.

Gliosarcoma is a rare malignant neoplasm. It accounts for approximately 2% of all glioblastomas. To date, there is no established treatment method for gliosarcoma, and a variety of therapies, such as surgical resection, radiotherapy, and chemotherapy, are typically employed. Here, we describe a patient with gliosarcoma who, despite multiple tumor metastases throughout the body, including the lungs and lymph nodes, achieved a relatively long survival due to salvage therapy with local irradiation and remarkably effective chemotherapy with low-dose ifosfamide, carboplatin, and etoposide therapy. When the patient died, we performed autopsy and confirmed the nature of the primary and metastatic tumor cells that had spread throughout the patient's body. Clinical and systemic histological studies also suggested the possibility of re-metastasis to the brain from systemic metastatic foci. Gliosarcoma appears to have characteristics similar to sarcoma as well as a higher risk of systemic metastasis. Therefore, a careful follow-up is necessary in such patients.

Kissing aneurysms refer to the condition in which two cerebral aneurysms with separate necks are in contact with each other. At present, there is scarce information on kissing aneurysms occurring near the vertebral artery (VA) -posterior inferior cerebellar artery (PICA). We report the first case of VA-PICA and nonbranched PICA kissing aneurysms, which were successfully treated with contralateral stenting after the anchor coil technique using two microcatheters. A 64-year-old woman was diagnosed with a left VA-PICA aneurysm (5.5 mm) and an adjacent small PICA aneurysm (2.5 mm) with the aneurysmal walls in close contact. For stenting, microcatheters were navigated to the PICA from the contralateral side, and framing coils for the anchor were placed into each aneurysm from the ipsilateral side. Next, a Neuroform Atlas stent was deployed from the PICA to the distal side of the VA, and coiling was completed using the jailing technique. The patient had a good postoperative course, and a left vertebral angiogram revealed complete occlusion of both aneurysms after 6 months. Adequate surgical planning and application of an appropriate stent-assisted coil embolization technique contributed to the success of the procedure in this rare case.

Although high-dose methotrexate (HD-MTX) is the standard therapy for primary central nervous system lymphoma (PCNSL), the prognosis remains poor. Because 90% of PCNSL is diffuse large B-cell lymphoma (DLBCL), chimeric antigen receptor (CAR) -T cell therapy is expected to be beneficial. However, there are limited reports on CAR-T cell therapy for PCNSL because of the concern of neurotoxicity. Here, we report a case of relapsed PCNSL treated with anti-CD19 CAR-T cell therapy. A 40-year-old woman presenting with visual disturbance in her left eye was initially diagnosed with bilateral uveitis. Her histological diagnosis was DLBCL, and she was positive for CD19. Although she received chemotherapy including HD-MTX, the tumor relapsed in her right occipital lobe. She underwent remission induction therapy and then anti-CD19 CAR-T cell therapy. Cytokine release syndrome (CRS) grade 2 occurred, but there were no complications of CAR-T cell-related encephalopathy syndrome (CRES). She has achieved complete response for more than 1 year. Anti-CD19 CAR-T cell therapy is a revolutionary immunotherapy for treating relapsed or refractory (R/R) B lineage malignancies. Although there are concerns regarding CRS and CRES in central nervous system lymphoma, the use of anti-CD19 CAR-T cells to treat R/R PCNSL is safe and feasible.

Meningoencephalocele in the lateral sphenoid sinus (SS) has been determined to be a rare entity often detected by cerebrospinal fluid (CSF) rhinorrhea. To date, the pathology of meningoencephalocele in the lateral SS has remained to be unclear in many cases. In this study, we report on a case of a 72-year-old woman with an arteriovenous malformation who presented with CSF rhinorrhea. Radiologic investigations revealed a left temporal meningoencephalocele in the lateral SS. We removed the meningoencephalocele and performed skull base repair, after which the CSF rhinorrhea resolved. Pathological examination showed congenital cortical abnormalities with dysmorphic neurons in various shapes and acquired chronic tissue alterations including fibrillary gliosis and scattered Rosenthal fibers. These findings may further aid in understanding the etiopathogenesis of meningoencephalocele in the lateral SS.

In this article, we report a case wherein a brain tumor was suspected based on computed tomography and magnetic resonance imaging findings. We made an initial diagnosis of malignant brain tumor based on methionine-positron emission tomography (PET) findings, but the correct diagnosis was dural arteriovenous fistula (DAVF). The patient was a 45-year-old man with DAVF who developed headache. Methionine-PET imaging showed high methionine uptake in the lesion. Although the tumor was strongly suspected from the findings of methionine-PET, the diagnosis of DAVF could be made correctly only by interpreting digital subtraction angiography and computed tomographic angiography. The findings of methionine-PET, which is considered useful in the diagnosis and denial of brain tumors, made the diagnosis of DAVF more difficult. The increased uptake of methionine-PET in DAVF is an important finding because, to our knowledge, this study is the first to report such finding. The results of this study might be useful for differential diagnoses when the diagnosis is uncertain.

Arachnoiditis ossificans (AO) is a rare disease, wherein ossified lesions in the subarachnoid space obstruct the flow of spinal fluid or compress the spinal cord, thereby causing myelopathy. Here we describe a rare case of AO and discuss the diagnosis and treatment strategies for this disease. A 66-year-old man with a history of subarachnoid hemorrhage presented with gait disturbance and dysuria for 7 months. Spinal magnetic resonance imaging and computed tomography (CT) myelography showed syringomyelia at the T5-T8 level and dorsally tethered spinal cord at the T8-T10 level. Preoperative noncontrast CT was not performed. The patient was diagnosed with adhesive arachnoiditis and underwent arachnoidolysis. However, intraoperative findings showed the presence of ossification lesions on the dorsal surface of the spinal cord, and intraoperative ultrasound (IOU) showed a hyperintense lesion with acoustic shadowing on the dorsal surface of the spinal cord, with limited visibility of the spinal cord. After removal of the lesions, IOU showed untethered and well-decompressed spinal cord and restoration of cerebrospinal fluid pulsation. Based on these findings, the patient was finally diagnosed with AO, which is an extremely rare disease, with an unknown frequency of occurrence. Therefore, all patients with adhesive spinal arachnoiditis require a preoperative noncontrast CT scan to evaluate for ossification lesions. In this case, we were fortunate to be able to treat AO with IOU, which demonstrated specific findings.

Choroid plexus carcinomas (CPCs) are rare malignant tumors of neuro-ectodermal origin, accounting for less than 1% of all intracranial tumors. The recurrence rates of CPCs are very high and typically occur in the short-term following surgery, even after gross total removal. Here we present a rare case of CPC with spinal metastasis, which occurred long after its initial presentation. A 25-year-old woman with a history of increased intracranial pressure underwent resection for a tumor of the fourth ventricle, with a histopathological diagnosis of CPC. After tumor resection, she received 30 Gy of radiation therapy to the craniospinal axis and 20 Gy to the primary site, followed by nimustine hydrochloride chemotherapy. The residual lesion completely responded to these treatments. She suffered sensory loss in the sacral region 13 years later, followed by refractory skin ulcer in the sacral region 17 years after the initial treatments. Magnetic resonance imaging at 17 years after the initial treatments showed tumor in the sacral region, which was enlarged upon follow-up after 18 months, causing incontinence and loss of urinary intention. She underwent tumor resection, with a histological diagnosis of recurrent CPC. She received salvage re-irradiation. This case shows that CPC can spread via the cerebrospinal fluid pathways and cause spinal metastasis, with relatively slow clinical course. The present case suggests that patients with CPCs may need long-term follow-up imaging of the total neural axis to identify late recurrence at both the primary site and spinal metastasis.