Dissecting aneurysms of the anterior inferior cerebellar artery (AICA) are rare. Few reports suggested that coil embolization and parent artery occlusion (PAO) would be valuable treatment options against dissecting AICA aneurysms. We report a case of PAO against dissecting aneurysm involving the proximal AICA and discuss the therapeutics and literature review of this pathology. A 69-year-old woman was referred to our hospital, and neurological examination revealed a semicoma (Hunt and Hess grade IV). Brain computed tomography (CT) established the diagnosis of Fisher group 3 subarachnoid hemorrhage (SAH), CT angiography revealed an extravasation near the clivus, while digital subtraction angiography showed no signs of dissection. Conservative treatment was administered, and repeated angiography on day 13 showed a pseudoaneurysm and false lumen in the left proximal AICA. The patient was in poor health condition, and endovascular therapy (EVT) of the left AICA was performed to minimize invasion. The PAO was successful with no severe ischemic damage to the brainstem and cerebellum. However, the general condition gradually deteriorated, and the patient expired on day 24. Since open surgery for dissecting AICA aneurysm is technically challenging and revascularization procedure is often required, the rapidly developing EVT is a viable alternative. Although preservation of the proximal AICA is usually necessary, PAO without revascularization procedure was performed to avoid the high risk of regrowth and re-rupture of the dissecting aneurysm with respect to the patient’s poor health condition. Hence, EVT is a viable option when microsurgery is contraindicated for treating dissecting AICA aneurysms.

Papillary glioneuronal tumor (PGNT) is a low-grade biphasic neoplasm with astrocytic and neuronal differentiation. This tumor occurs most commonly in the frontal and temporal lobes, close to the ventricles, and rarely in the cerebellum, brainstem, and pineal gland. However, there has been no report of this tumor in the suprasellar region to date. In this paper, we report a case of PGNT in the suprasellar region in a 16-year-old girl. Magnetic resonance imaging (MRI) revealed a cystic tumor with calcification that progressed from the anterior skull base to the suprasellar and temporal regions. Preoperatively distinguishing this tumor from craniopharyngioma was difficult because of the patient’s age, localization of the tumor, and neuroimaging results. This case showed a backward shift of the chiasma, which is observed in only 4.7% of craniopharyngioma, as well as normal endocrine findings. Endocrinological examination and an MRI evaluation of the chiasmal shift may be useful for discrimination.

We report a rare case of a solitary synovial osteochondroma (SSO) in the cervical canal. A 37-year-old man presented with neck pain and the forearm dysesthesia developed immediately after a trivial motor accident. Because of aggravation he visited our hospital though he was treated conservatively for 3 months. A computed tomography (CT) scan showed an oval shaped small mass with high density rim in the cervical canal at the level of the C6/7 facet joint. This mass compressing the dural sac was visualized with a high intensity signal in T2-weighted magnetic resonance imaging (MRI) and, interestingly, with high intensity in T1-weighted images. A surgical removal was carried out. Macroscopically, it consists of a solitary, firm, juxta-articular mass associated with synobia but lacking connection with the adjacent bone. Microscopically, it is similar to conventional osteochondromas. It differs from this entity by not arising from a bone surface and by a whole coverage of synobial tissue. The final diagnosis was a SSO. There have been anecdotal case reports of a SSO in various site including knee, fingers, buttocks, wrist, and so on. To the best of our knowledge, this is the first case report of SSO arising in the spinal canal.

Basilar artery perforator aneurysms (BAPAs) are a rare cause of subarachnoid hemorrhage (SAH), and the natural history is still unknown. Herein, we report a case of ruptured BAPA that appeared during the observation period and then spontaneously disappeared; we have also conducted a review of the literature and performed an analysis based on the type of management. This case of BAPA had a unique course, and our observations may help establish a treatment strategy. A 60-year-old man presented with acute diffuse SAH, World Federation of Neurosurgical Societies (WFNS) Grade II and Fisher Grade 3. Initial three-dimensional digital subtraction angiography (DSA) did not show the source of the hemorrhage. DSA performed on day 39 showed a BAPA with a diameter of 3 mm at the posterior surface of the upper third of the basilar artery. Conservative treatment was chosen. DSA performed on day 64 showed complete resolution of the aneurysm. BAPAs are likely pseudoaneurysms, and not saccular aneurysms, caused due to dissection of basilar perforator arteries. BAPAs are often not recognized on initial imaging, and hence, it is necessary to repeat the DSA examination. Considering the relatively high rate of spontaneous resolution, we chose conservative management. When BAPAs enlarge or do not disappear after conservative treatment, additional therapy such as multiple stents should be considered.

Cerebral tumor embolism is a rare cause of acute ischemic stroke, and extracardiac carcinoma is an extremely rare cause. A 34-year-old man who had been diagnosed with lung cancer developed right hemiparesis and aphasia, with the National Institutes of Health Stroke Scale (NIHSS) score of 17. Magnetic resonance imaging (MRI) showed early ischemic change in the insular cortex and frontotemporal lobe and left internal carotid artery (ICA) terminal occlusion was confirmed by magnetic resonance angiogram (MRA). Mechanical thrombectomy (MT) with contact aspiration by a Penumbra ACE 68, followed by combined technique with a stent retriever was performed, and a soft, fragile embolus was retrieved. Finally, good recanalization was achieved (Thrombolysis in Cerebral Infarction [TICI] scale 2b), and on the next day, the right hemiparesis and aphasia were improved. However, the patient’s general condition gradually worsened, and 43 days after thrombectomy, he died from respiratory failure. The retrieved embolus was examined pathologically and diagnosed as mucoepidermoid carcinoma of the same type as his lung cancer. Chest computed tomography (CT) showed that tumor invaded the right pulmonary vein and left atrium; these findings suggested that a piece of the tumor in the left atrium flowed into the left ICA and caused the acute ischemic stroke.

Primary tumors of sacrum are rarely seen, and the differential diagnosis is extensive, such as chordomas, giant cell tumors, and schwannomas. Sacral intraosseous schwannomas (IOSs) are very rare and encompass approximately 1%–5% of all spinal schwannomas. Melanotic schwannomas (MSs) are categorized as an unusual variant of benign schwannomas; however, they sometimes follow a malignant course. The authors present a case of MS with intraosseous extension into sacrum in a 48-year-old male arising from the left S2 nerve root. Magnetic resonance imaging (MRI) and computed tomography (CT) scan demonstrated a destructive mass in the sacrum. He was made a diagnosis with MS by 18F-fluoro-deoxy-glucose positron-emission-tomography (¹⁸F-FDG PET) and open biopsy. The tumor was blackish-colored and vascular-rich fragile tumor covered by fibrous capsule. The floor of the tumor was not encapsulated and invading into the sacral bone. Total removal of the tumor together with the left S2 nerve of origin via posterior approach was achieved. The patient made dramatic recovery of neurological symptoms and tumor recurrence is not seen for 6-month follow-up period. MS is a benign tumor with potential for aggressive behavior and capacity to metastasize. Therefore, total removal of the tumor and careful postoperative follow-up are recommended. Postoperative spinopelvic stability also needs to be taken into consideration. The authors discuss our successful management with a focus on diagnostic process, surgical planning, and histological consideration to provide the most up-to-date guidance on managing this challenging tumor.

Double origin of the posterior inferior cerebellar artery (DOPICA) is rare but is associated with intracranial aneurysm formation. A 46-year-old man was brought to our hospital with severe subarachnoid hemorrhage (SAH). Digital subtraction angiography revealed right vertebral artery dissecting aneurysm (VADA) and DOPICA. The aneurysm involved the distal component of the posterior inferior cerebellar artery. The proximal component covered the original flow angiographically. Endovascular internal trapping and parent artery occlusion were performed for the aneurysm and the right vertebral artery (VA). Flow of the posterior inferior cerebellar artery was preserved by the proximal component of the posterior inferior cerebellar artery after trapping. The patient unfortunately died and autopsy revealed ischemic change in the right medulla oblongata. The ischemic change was considered to occur at the treatment according to the pathological findings. Sacrifice of one component of DOPICA to treat VADA with the expectation of preserved flow via the other component should be considered cautiously in terms of the neurovascular anatomy.

Ganglioneuroma is a rare tumor. Such tumor arising from cranial nerve is further rare. So far our knowledge, in the literature there is no report of ganglioneuroma involving glossopharyngeal nerve. Here, we report a case of very small glossopharyngeal nerve ganglioneuroma and the patient also had longstanding glossopharyngeal neuralgia (GPN).

Case Report: A 40-year-old male diagnosed case of left GPN for last 7 years presented with gradual unresponsiveness of drug for last 5 years. Due to severity of pain sometime, he wished to do suicide. Magnetic resonance imaging (MRI) of head revealed only suspected loop of vessel in root entry zones of 9th and 10 cranial nerves on left side. The patient underwent explorative posterior fossa craniotomy. Careful dissection of arachnoid over 9th cranial nerve near jugular foramen (JF) revealed thick and red color nerve with nodularity (tumor like). Dissection of arachnoid at nerve root entry zones of 9th and 10th nerves also revealed an aberrant loop of posterior inferior cerebellar artery (PICA). The 9th nerve was transected and suspected “tumorous portion” of nerve was sent for histopathological examination. The PICA loop was dissected away from root entry zones by placing muscle and surgical between 10th nerve roots and PICA loop. He made an uneventful recovery. Histopathological examination revealed ganglioneuroma. Immunohistochemistry confirmed ganglioneuroma. Six months after the operation, he was free of symptoms. In this case, probably previously existing GPN was worsen by the growth of ganglioneuroma and surgical treatment brought gratifying result.

Methotrexate (MTX) is an immunosuppressor that is widely used to treat autoimmune diseases, including rheumatoid arthritis (RA). However, it can have serious adverse effects including a lymphoma: MTX-associated lymphoproliferative disorder (MTX-LPD). Extranodal lesions are common in MTX-LPD patients. However, MTX-LPD in the central nervous system (CNS) is extremely rare with few reported cases. Here, we describe a case of primary CNS MTX-LPD in a patient with RA, with a review of the literature. A 68-year-old woman who had received MTX for her RA for more than 10 years was referred to our hospital. Head magnetic resonance imaging (MRI) showed multiple lesions with heterogeneous contrast enhancement scattered throughout both hemispheres. As immunosuppression caused by MTX was suspected, MTX was discontinued, based on a working diagnosis of MTX-LPD. We performed an open biopsy of her right temporal lesion. Histopathologic examination showed atypical CD20+ lymphoid cells, leading to a definitive diagnosis of diffuse large B-cell lymphoma (DLBCL). In situ hybridization of an Epstein-Barr virus-encoded small RNA (EBER) was positive. Sanger sequencing confirmed that both MYD88 L265 and CD79B Y196 mutations were absent. The LPD regressed after stopping MTX. Follow-up head MRI at 8 months after surgery showed no evidence of recurrence. Although primary CNS MTX-LPD is extremely rare, it should be included in the differential diagnosis when a patient receiving MTX develops CNS lesions. Diagnosis by biopsy and MTX discontinuation are required as soon as possible.

Fluoroscopy-guided radiofrequency thermocoagulation of the trigeminal ganglion is an alternative treatment for symptomatic trigeminal neuralgia. The most common complications of the procedure are circumscribed to sensitivity alterations. We report a case of an 83-year-old female patient with a history of petroclival meningioma resection, radiotherapy at the level of the petrous apex, and radiofrequency thermocoagulation for trigeminal neuralgia who developed a symptomatic dural arteriovenous fistula as an early complication, which required selective embolization. Dural arteriovenous fistula as an immediate complication of percutaneous thermocoagulation of the trigeminal ganglion has not been previously reported.

Intracranial subdural abscess is a rare condition. Although brain abscess is often reported in relation to dental infection, reports of intracranial subdural abscess are few. Actinomyces spp. forms part of the normal flora of the oral, gastrointestinal, and genital tract, and is rarely the cause of intracranial infection; moreover, the pathogen Actinomyces meyeri is very rare. We report an exceptional case of intracranial subdural abscess caused by A. meyeri and related to dental treatment.

A 57-year-old woman initially presented with a 5-day history of headache. Because left arm numbness and weakness became apparent, she was admitted to our department. She had a history of hypertension and dental problems requiring tooth extractions. Diffusion-weighted imaging (DWI) showed a 1-cm right convexity hyperintense mass above the postcentral gyrus. A post-gadolinium T1-weighted image showed a thin hypointense area with peripheral rim enhancement in the right subdural space that appeared to partially thicken in the same location as the DWI-positive mass. She underwent emergent navigation-guided drainage and 4 mL of pus was obtained. Postoperatively, left arm numbness and weakness disappeared. Cultures showed growth of A. meyeri and Fusobacterium nucleatum. She was started on intravenous penicillin G and metronidazole. After a 4-week course of the intravenous antibiotics, her headache gradually improved and the abscess in the subdural space subsided.

To our best knowledge this is the first case report of intracranial subdural abscess caused by A. meyeri associated with dental treatment.

The pathophysiology and optimal treatment for hydrocephalus with Blake’s pouch cyst (BPC) remain controversial. The authors present two pediatric cases of hydrocephalus associated with BPC, in which the patients’ hydrocephalus progressed after endoscopic third ventriculostomy (ETV), despite a patent stoma of the third ventricular floor.

Case 1: A 4-year-old girl with delayed gait development was diagnosed with BPC-associated hydrocephalus and received ETV. Postoperatively, the patient presented headaches and nausea. Computed tomography (CT) scans demonstrated larger ventricles than those observed on the preoperative images. Because phase-contrast cine magnetic resonance imaging (MRI) and constructive interference in steady state (CISS) MRI revealed patent cerebrospinal fluid (CSF) flow at the third ventricular floor level, a ventriculoperitoneal shunt (VPS) was placed using a programmable pressure valve to treat the hydrocephalus.

Case 2: A 6-year-old girl with newly developed repeated convulsive seizures was diagnosed with BPC-associated hydrocephalus and received ETV. Phase-contrast cine MRI on the 5th postoperative day showed hyperdynamic CSF flow at the third ventricular floor level. She also developed vomiting and headache 6 weeks after ETV. CT scans demonstrated much larger tetraventricular hydrocephalus than that observed on the preoperative images. VPS placement improved her hydrocephalus.

Referencing the previous literature, we discuss the CSF dynamics and the mechanism of BPC-associated hydrocephalus, focusing on the third ventricular floor bulging. We hope our experience will help elucidate the pathophysiology and treatment strategies for BPC-associated hydrocephalus.