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Anatomical variations often occur in the anterior communicating artery (AComA) complex, and a careful preoperative evaluation is required before repair of this lesion. We report a case of a fenestrated AComA complex mimicking an unruptured cerebral aneurysm. A 49-year-old woman was referred to our hospital under suspicion of unruptured aneurysms of the AComA and the left middle cerebral artery on magnetic resonance angiography (MRA). Additional three-dimensional computed tomographic angiography (CTA) showed the lesion arising from the AComA complex with a maximum diameter of 4.2 mm. Intraoperative findings showed that the putative aneurysm was actually a fenestrated AComA complex as the blood vessels that formed the AComA complex were dilated and meandering. After the operation, MRA and CTA three-dimensional images were reviewed again but we could still not diagnose the lesion as a fenestrated AComA complex rather than an aneurysm. However, in the MRA source image, a secant line in the lesion was the only finding suggestive of a fenestration. The AComA complex is often associated with various vascular malformations, and it is essential to consider this association in the preoperative evaluation. The interpretation of source images may be helpful for accurate diagnosis and surgical planning.

BACKGROUND Aplastic or twiglike middle cerebral artery (Ap/T-MCA) is a rare anomaly characterized by a unilateral MCA occlusion with plexiform vessels that causes hemorrhagic and (less commonly) ischemic strokes. The reasons for this are rarely discussed, and thus optimal treatment for ischemic Ap/T-MCA remains controversial. Here, the authors report a case of Ap/T-MCA with transient ischemic attacks treated by bypass surgery and discuss the mechanism of ischemic development and treatment methods. OBSERVATIONS A 62-year-old hypertensive man with transient, recurrent left hemiparesis visited the authors’ hospital. Magnetic resonance angiography showed proximal occlusion of the right MCA and stenosis in the left MCA. Digital subtraction angiography revealed occlusion of the right MCA and abnormal vascular networks, leading to a diagnosis of Ap/T-MCA with contralateral MCA stenosis. Antiplatelet therapy with aspirin was insufficient, and a superficial temporal artery–MCA bypass was performed. There were no ischemic or hemorrhagic events postoperatively. LESSONS Atherosclerosis seems to have a significant impact on the development of ischemic stroke in patients with Ap/T-MCA, and the presence of coexisting atherosclerotic stenotic vascular lesions outside the Ap/T-MCA site is substantial in its development. Bypass surgery is a promising treatment option for ischemic Ap/T-MCA.

Spontaneous radiographic disappearance of cerebral aneurysms is often observed under special conditions such as giant aneurysms. However, spontaneous disappearance of an unruptured and nongiant intracranial saccular aneurysms is rare. We describe two cases of this rare vascular phenomenon. The first patient is a 64-year-old female diagnosed with a small unruptured aneurysm arising from the distal anterior cerebral artery. Spontaneous disappearance of the aneurysm on magnetic resonance angiography (MRA) was observed 5 years after the initial diagnosis. Continuous imaging surveillance also revealed spontaneous reappearance of the aneurysm 2 years later. The second patient is a 57-year-old female harboring a small unruptured saccular aneurysm arising from the M1–M2 bifurcation of the middle cerebral artery. The aneurysm showed spontaneous disappearance on MRA 13 years after the initial diagnosis. These cases provide a new insight into this natural dynamic process even in cases of a small unruptured intracranial saccular aneurysm.

Anterior cranial fossa (ACF) dural arteriovenous fistulas (DAVFs) are mainly fed by the ethmoidal arteries and sometimes have pial arterial feeders. DAVFs with pial arterial supply in ACF are extremely rare because most of the reported cases of DAVFs with pial arterial supply are located at the transverse sigmoid sinus and tentorium. A 68-year-old male presented with dizziness. Angiography showed cortical venous reflex (CVR) through an ACF DAVF fed by both bilateral ethmoidal arteries and by the right orbitofrontal artery as a pial feeder. The ethmoidal feeders were disconnected by craniotomy. The pial arterial feeder from the anterior cerebral artery was not found during surgery, and disconnection of the draining vein was not performed. CVR showed a significant reduction after the surgery. After 2 years of follow-up, angiography revealed an increased shunt flow from the pial feeder. Endovascular treatment using n-butyl-2-cyanoacrylate was performed, resulting in the complete occlusion of the fistula. DAVFs with pial supply are reported to carry a high risk of perioperative complications because of the restriction of the venous outflow and retrograde thrombosis of the pial artery. Endovascular pial feeder occlusion after surgical dural arterial feeder disconnection might achieve a safe and effective outcome. With close follow-up, the recurrence of increased shunt flow may be an appropriate timing for additional treatment. This rare condition may offer a new insight into the mechanisms of pial feeder development.

Background: Brain abscesses are relatively rare life-threatening infectious lesions often concomitant with a direct spillover of inflammation in the head or neck, hematogenous infections, and immunocompromised conditions. They rarely occur in adults without such predisposing factors. Prevotella is a well-known dental pathogen that very rarely causes brain abscesses. Case Description: We report such an abscess in a 51-year-old man who was innately healthy and had no oral lesions. A comprehensive computed tomography examination of the chest, abdomen, and pelvis, was inconclusive but a transesophageal echocardiogram bubble study revealed a mild patent foramen ovale (PFO) that matched Grade 1 criteria. We deduced that the right-left shunt due to the PFO could have contributed to the brain infection and treated the patient successfully via surgical abscess aspiration and antibiotics. Conclusion: In case of a brain abscess occurring in healthy adults, it is essential to investigate the source of infection and the existence of an arterio-venous shunt, such as PFO.

Background: Calvarial bone thinning is a rare clinical entity, with only several cases reported (including Gorham-Stout disease), but the cause is often unknown. Here, we report such a case of unilateral calvarial thinning with an unknown cause. Case Description: A 77-year-old woman undergoing imaging examination for unruptured cerebral aneurysms for the past several years noticed a progressive cranial deformity. Computed tomography revealed progressive thinning of the right parietal bone and cranial deformity but laboratory tests showed no causative findings. A cranioplasty was performed to protect the brain and confirm the pathology. Grossly, pigmentation and deformity were observed on the outer plate of the bone but the inner plate was intact. Pathological examination revealed preserved bone cells and no necrosis. In addition, there were no findings of vascular hyperplasia or malignancy. It appeared that localized osteoporosis had occurred, mainly in the outer plate of the bone, but the cause was unclear. Conclusion: Progressive focal calvarial thinning is rarely reported and the mechanism in this case was unknown. It is important to determine the cause of the bone thinning to evaluate the need for surgical intervention from the viewpoint of brain protection and prevention of cerebrospinal fluid leakage.

BACKGROUND Aplastic or twig-like middle cerebral artery (Ap/T-MCA) is a congenital MCA anomaly. It may present with symptoms of both hemorrhage and ischemia, similar to moyamoya disease, and hemodynamic stress may play an essential role in the development of symptoms in both clinical entities. The optimal treatment remains controversial in symptomatic patients with Ap/T-MCA. This report discussed the treatment method for a patient with Ap/T-MCA with unruptured aneurysms who presented with intraventricular hemorrhage (IVH) treated by aneurysm clipping and bypass surgery. OBSERVATIONS In a 46-year-old woman with a sudden headache, computed tomography showed left IVH. Magnetic resonance angiography showed a left MCA aneurysm and MCA trunk stenosis. Three-dimensional angiography demonstrated a plexiform arterial network and multiple aneurysms arising from the MCA and in the plexiform network, leading to the diagnosis of Ap/T-MCA harboring unruptured aneurysms. The patient was successfully treated by craniotomy with aneurysm clipping and bypass surgery to prevent further intracranial hemorrhages and/or aneurysm rupture. LESSONS Especially in cases such as Ap/T-MCA, in which hemodynamic stress has a significant effect, the optimal treatment method should be based on vascular morphology and the impact of hemodynamic stress.

BACKGROUND Extracranial arteriovenous malformations (AVMs) are rare clinical entities and on rare occasions cause neurological symptoms. The authors report a case of an extracranial pterygoid AVM and a subsequent contralateral cavernous sinus dural arteriovenous fistula (dAVF) presenting with abducens nerve palsy. OBSERVATIONS An 80-year-old woman was referred to the authors’ hospital with left abducens nerve palsy followed by right ophthalmalgia. Magnetic resonance imaging (MRI) showed abnormal vessel staining in the left pterygoid and the right inferior petrosal sinus (IPS). Cerebral angiography revealed a left pterygoid AVM draining into the right IPS via the cavernous sinus (CS). A dAVF in the right CS was also revealed. The right ophthalmalgia disappeared spontaneously, and, 4 months later, the left abducens nerve palsy also disappeared after conservative management. Follow-up MRI showed spontaneous regression of the AVM and dAVF. The disappearance of the dAVF was considered to be due to spontaneous regression of the left pterygoid AVM and the consequent decrease in venous pressure of the CS, and the symptoms eventually disappeared. LESSONS The authors treated an extremely rare case of extracranial AVM with dramatic changes in vascular structure and symptoms. Understanding of the pathophysiology between symptoms and dynamic changes in the vascular structure is essential for providing the appropriate treatment.

Background: Hemorrhagic stroke is caused by various vascular abnormalities, such as aneurysms, arteriovenous malformations, and dural arteriovenous fistulas (DAVF). Magnetic resonance angiography (MRA) and three-dimensional computed tomography angiography (3DCTA) are used as efficient initial diagnostic modalities in assessing the etiology of hemorrhagic stroke. We describe the unusual case of a false-positive aneurysm on MRA and 3DCTA. Case Description: A 65-year-old nonhypertensive woman was brought to our hospital with a sudden onset of headache and left hemiparesis. She also had chemosis in the right eye. CT and magnetic resonance imaging showed an intracerebral hemorrhage in the right temporal lobe. MRA and 3DCTA showed a rounded mass suggestive of an aneurysm arising from the bifurcation of the middle cerebral artery (MCA) and also demonstrated an abnormal tortuous vessel contacting with a rounded mass. Digital subtraction angiography showed a transversesigmoid sinus DAVF with a varix in contact with the MCA bifurcation. Hematoma evacuation and venous drainage disconnection through the right frontotemporal craniotomy were performed. Conclusion: This case is very instructive and clinicians should keep in mind that detailed neurological and radiological examinations are essential in obtaining an accurate diagnosis, especially if the bleeding source is similar in shape and location to common lesions (such as a cerebral aneurysm).

Temozolomide (TMZ) as a concomitant and adjuvant chemotherapy to radiotherapy following maximal surgical resection is the established standard therapy for patients with newly diagnosed high-grade glioma. However, detailed analysis of chemotherapy-induced nausea and vomiting (CINV) associated with concomitant TMZ has not been sufficiently described. We prospectively analyzed the profile of CINV associated with concomitant TMZ. Eighteen consecutive patients with newly diagnosed high-grade glioma treated with concomitant chemoradiotherapy including TMZ were enrolled. CINV was recorded using a daily diary including nausea assessment, emetic episodes, degree of appetite suppression, and antiemetic medication use. The observed incidence rates of all grade nausea, moderate/severe (CTC grade 2, 3) nausea, emetic episodes, and appetite suppression for the overall period were 89%, 39%, 39%, and 83%, respectively. Moderate/severe nausea and severe (CTC grade 3) appetite suppression were frequently observed during the delayed phase of the treatment. Emetic episodes and moderate/severe nausea were significantly correlated with female gender. Moderate/severe nausea and severe appetite suppression were significantly correlated with low lymphocyte counts before chemoradiotherapy. For CINV associated with concomitant TMZ, enhanced antiemetic therapy focused on the delayed phase of the treatment will likely be beneficial, especially in female patients with a low lymphocyte count before chemoradiotherapy.

We report the unique case of a 69-year-old man with a cerebellar glioblastoma showing an exophytic growth pattern. Magnetic resonance imaging revealed a heterogeneously gadolinium-enhancing tumor in the right cerebellopontine angle. The preoperative differential diagnoses included an intraaxial tumor, such as high-grade glioma, and an extraaxial tumor, such as a meningioma or neurinoma. The tumor with a clear boundary was subtotally removed, except for the adhesion site to the petrosal vein, and the histologic diagnosis was glioblastoma. Immunohistochemical analyses demonstrated that the tumor cells were immunopositive for epidermal growth factor receptor and immunonegative for p53 mutation and IDH1 R132H, indicating that it had different genetic features from a typical cerebellar glioblastoma. Conventional radiotherapy with 60 Gy concurrent with temozolomide was performed, and the condition of the patient has remained stable for 24 months since the operation. Exophytic cerebellar glioblastoma should be considered in the differential diagnosis of cerebellopontine angle tumor.

Clinically, recurrent glioblastoma multiforme (GBM) is often associated with communicating hydrocephalus. We hypothesized that there are specific magnetic resonance (MR) imaging findings at the diagnosis of recurrent GBM that predict subsequent hydrocephalus. Various clinical characteristics were investigated including outcome and MR imaging findings in 12 patients with recurrent GBM followed by hydrocephalus (Hydro group) and 21 patients with recurrent GBM without hydrocephalus (Non-hydro group). Patient age and presence of communicating hydrocephalus were significantly associated with poor outcome. Median survival with recurrent GBM was longer in the Non-hydro group than in the Hydro group. Low Karnofsky performance status (KPS) and poor recursive partitioning analysis (RPA) class (RPA class 3, 5, 6, or 7) at the diagnosis of recurrent GBM were associated with the presence of hydrocephalus. The incidence of leptomeningeal dissemination after recurrent GBM was higher in the Hydro group than in the Non-hydro group. Evans index and fractional anisotropy value showed no difference at the diagnosis of recurrent GBM, but some MR imaging findings indicated that lesion attached to the basal cistern and/or ventricle was closely associated with subsequent hydrocephalus. We recommend careful monitoring of the ventricle size and leptomeningeal dissemination, especially in patients with low KPS and/or poor RPA class, if MR imaging indicates that the lesion is attached to the basal cistern and/or ventricle at recurrence of GBM.

Small unruptured aneurysms are thought to have a low risk of rupture, but the management of such lesions is still controversial. A 73-year-old man with a small anterior communication artery aneurysm, 4 mm in diameter, while on follow-up, developed an aneurysmal subarachnoid hemorrhage 2 weeks after the detection of a newly emerged bleb on the surface of the aneurysm. In conclusion, the formation of a bleb should be considered as a warning sign of an impending rupture, and treatment should be provided even for patients with small aneurysms.

We present a case that is most likely Lemierre's syndrome. A 19-year-old man presented to us with -common-cold-like symptoms, which he had had for 2 days, such as slight fever, general malaise, anorexia, sore throat, and headache. Eight days after the onset of these symptoms, he died of brain herniation due to cerebral venous thrombosis associated with micro-abscesses detected in pathological examination.

We present a case that is most likely Lemierre’s syndrome. A 19-year-old man presented to us with ­common-cold-like symptoms, which he had had for 2 days, such as slight fever, general malaise, anorexia, sore throat, and headache. Eight days after the onset of these symptoms, he died of brain herniation due to cerebral venous thrombosis associated with micro-abscesses detected in pathological examination.

Background: The authors report a case of intraparenchymal germinoma pathologically diagnosed using navigation-guided endoscopic biopsy. Case Description: A 27-year-old man had mild left hemiparesis, transcortical motor aphasia, and amnesia. Magnetic resonance (MR) imaging revealed an intraparenchymal mass lesion near the left ventricular trigone. Navigation-guided endoscopic biopsy was performed, and histopathology revealed large neoplastic cells immunohistochemically positive for germinoma-specific antigens, which were diagnosed as pure germinoma. Chemotherapy with whole-brain radiotherapy was performed, and the neurological symptoms did not change during the treatment. Follow-up MR imaging 1 year after the surgery showed no evidence of recurrence or dissemination. Conclusions: Navigation-guided endoscopic biopsy can be a useful technique in such intraparenchymal germinoma cases.