[Internal carotid artery stenosis with repeated ischemic stroke recurrence due to mechanical stimulation by the hyoid bone and thyroid cartilage: a case report].

We present a case of internal carotid artery (ICA) stenosis caused by mechanical stimulation by the hyoid bone (HB) and thyroid cartilage (TC). A 78-year-old man with a history of right ICA stenting four years previously was admitted for abrupt onset of dysarthria and left hemiparesis and diagnosed with ischemic stroke by magnetic resonance imaging. Three-dimensional computed tomographic angiography revealed internal carotid in-stent restenosis. Furthermore, the HB and TC contacted with the right ICA. Treatment involved antiplatelet therapy, partial HB and TC resection, and carotid artery restenting. Posttreatmently, the ICA was restored and stenosis improved. Since restenosis may occur posttreatmently in patients with carotid artery stenosis caused by mechanical stimulation of the HB and TC, it is necessary to consider treatments including not only carotid artery stenting but also partial bone structures resection and carotid endarterectomy.

Case report: Unruptured small middle cerebral artery aneurysm with perianeurysmal edema.

Background: Perianeurysmal edema (PAE) has a tendency to occur in embolized aneurysms but also in partially thrombosed, large, or giant aneurysms. However, there are only a few cases recorded in which PAE was detected in untreated or small aneurysms. We suspected that PAE might be an impending sign of aneurysm rupture in these cases. Herein, we presented a unique case of PAE that was related to an unruptured small middle cerebral artery aneurysm. Case description: A 61-year-old woman was referred to our institute due to a newly formed abnormal fluid-attenuated inversion recovery (FLAIR) hyperintense lesion in the right medial temporal cortex. Upon admission, the patient did not present with any symptoms or complaints; however, FLAIR and CT angiography (CTA) suggested an increased risk of aneurysm rupture. Aneurysm clipping was conducted, and no evidence of subarachnoid hemorrhage and hemosiderin deposits around the aneurysm and brain parenchyma was noted. The patient was discharged home without any neurological symptoms. MRI taken at eight months post-clipping revealed complete regression of the FLAIR hyperintense lesion around the aneurysm. Conclusion: PAE in unruptured, small aneurysm is thought to be an impending sign of aneurysm rupture. Early surgical intervention is critical even for small aneurysms with PAE.

Endovascular treatment of an aneurysm arising from the minor limb of an upper basilar artery fenestration: illustrative case.

BACKGROUND: An aneurysm arising in an upper basilar artery (BA) fenestration is extremely rare. The authors reported a case involving successful endovascular treatment of an aneurysm arising from the minor limb of an upper BA fenestration. OBSERVATIONS: A 65-year-old woman presented with an incidentally detected upper BA aneurysm arising from the minor limb of an upper BA fenestration. The irregularly shaped aneurysm was 6.0 × 2.7 mm in diameter, and the minor limb had several perforators. The aneurysm was nearly completely occluded with a catheter-assisted technique. The authors preserved both limbs of the BA fenestration. The postoperative course was uneventful, and the patient had an excellent clinical course with no neurological deficits or aneurysmal recanalization. LESSONS: The case is the first report of an unruptured aneurysm arising at the minor limb of an upper BA fenestration. In this case, the authors preserved the minor limb with endovascular treatment. The authors believe catheter-assisted coil embolization to be a feasible endovascular technique in such cases.

Endovascular Coil Embolization for Recurrent Bow Hunter's Stroke.

Bow hunter's stroke is a rare cause of vertebrobasilar infarction. There is no consensus regarding the optimal treatment. We herein report a case of bow hunter's stroke successfully treated by endovascular treatment. A 70-year-old man presented with central vertigo. Magnetic resonance imaging (MRI) showed posterior circulation infarcts. Dynamic angiography revealed thrombus formation and hypoperfusion of the right vertebral artery upon head rotation to the left. Endovascular parent artery occlusion of the right vertebral artery was performed, and there was no recurrence at follow-up MRI. Endovascular parent artery occlusion might be a useful treatment for bow hunter's stroke.

Unruptured cerebral aneurysms with the segmental duplicated middle cerebral artery formed a fenestrated structure at origin.

BACKGROUND: Middle cerebral artery (MCA) has a significantly lower incidence of anatomical variations than other intracranial arteries. We present an extremely rare case of unruptured aneurysms with the segmental duplicated MCA (d-MCA) formed a fenestrated structure at origin. CASE DESCRIPTION: A 55-year-old female underwent direct surgery for the unruptured aneurysms at the top of the right internal cerebral artery with d-MCA. The d-MCA branches separated at the right internal cerebral artery top and had comparable with that of the main MCA trunk. Moreover, there was an anastomosis between the d-MCA branches. We diagnosed this anastomosis as segmental d-MCA. Two aneurysmal domes were identified during surgery at the origin of the d-MCA, which the main dome protruding backward was wide necked and another small one was collapsed or thrombosed protruding forward. We used a fenestrated clip for the posterior projecting dome, and the aneurysms were successfully obliterated. CONCLUSION: Although cerebral aneurysms associated with d-MCA are rare, there are technical difficulties in the surgical management. A fenestrated clip might be most reasonable to obtain patency of the parent arteries for the posterior projecting aneurysms if the perforators can be avoided.

Subarachnoid hemorrhage due to a craniocervical junction arteriovenous fistula associated with thrombus formation in the internal jugular vein: illustrative case.

BACKGROUND: A craniocervical junction arteriovenous fistula (CCJAVF) is a rare vascular malformation, and its etiology remains unclear. Here, to the best of the authors' knowledge, they present the first case of CCJAVF associated with thrombus formation in the ipsilateral internal jugular vein. OBSERVATIONS: An 80-year-old man presented with a sudden occipital headache. Computed tomography revealed a subarachnoid hemorrhage surrounding the brainstem and upper cervical cord. Digital subtraction angiography showed a CCJAVF fed by the left C2 radiculomeningeal artery with ascending intracranial drainage and epidural plexus. After endovascular treatment, the authors retrospectively found that his ipsilateral internal jugular vein and innominate vein were occluded with a huge thrombus at admission. LESSONS: This case suggested a restricted antegrade venous flow due to thrombus-induced progressive retrograde intracranial drainage causing hemorrhage. Venous hypertension should be considered one of the causes of hemorrhage due to CCJAVF as well as intracranial arteriovenous fistulas.

Unusual course of the vagus nerve passing anterior to the internal carotid artery during carotid endarterectomy.

BACKGROUND: Carotid endarterectomy (CEA) is a conventional surgical technique to prevent ischemic stroke and the effectiveness for advanced lesions is established in many large studies. The vagus nerve is one of the cranial nerves that we usually encounter during CEA manipulation, which is identified as located posterior to the vessels in a position posterolateral to the carotid artery and posteromedial to the internal jugular vein. CASE DESCRIPTION: We experienced an extremely rare case of the vagus nerve passing anterior to the internal carotid artery during CEA. CONCLUSION: We should be careful not to accidentally cut off because the variation of the vagus nerve can be mistaken for an ansa cervicalis. A delicate and complete dissection to understand the variation of the vagus nerve is crucial to minimize the risk of cranial nerve injury during CEA.

[Asymptomatic Aplastic or Twig-Like Middle Cerebral Artery Associated with Unruptured Cerebral Aneurysms at the Origin (A1) of a Collateral Artery and the Anterior Communicating Artery: A Case Report with Multiple Intracranial Atherosclerotic Stenoses].

We report a rare case of asymptomatic aplastic or twig-like middle cerebral artery (Ap/T-MCA) with small unruptured aneurysms at the origin (A1) of the anomalous collateral artery containing plexiform (twig-like) networks and in the anterior communicating artery. In Ap/T-MCA, other cerebrovascular systems are usually considered to exhibit normal findings not associated with atherosclerosis. At first admission, atherosclerotic M1 occlusion was suspected because of the patient's risk factors and multiple stenoses in major intracranial arteries. Cerebral blood flow (CBF) studies revealed reduction of resting CBF and vascular reserve in the ipsilateral MCA territory. After 5 years, a diagnosis of Ap/T-MCA was reached based on detailed image examination and intraoperative findings during aneurysm clipping in combination with extracranial-intracranial (EC-IC) bypass. It should be noted that atherosclerosis can coexist with Ap/T-MCA, which is considered a congenital anomaly in which bleeding often occurs due to a ruptured aneurysm within the fragile collateral vessels. In previous reports, A1 aneurysms at the origins of the collateral arteries ruptured even when they were small. Aggressive radical surgery using EC-IC bypass can be considered for the treatment of unruptured aneurysms associated with Ap/T-MCA, but further research is needed. (Received September 14, 2020; Accepted November 4, 2020; Published 1 April, 2021).

A1 Segment Unruptured Aneurysm of Persistent Primitive Olfactory Artery Coexisted with Accessory Middle Cerebral Artery.

A persistent primitive olfactory artery (PPOA) is a rare anomaly of anterior cerebral artery (ACA), which generally arises from the internal carotid artery (ICA), runs along the olfactory tract, and makes a hairpin bend to supply the territory of the distal ACA. PPOA is also associated with cerebral aneurysms. An accessory MCA is a variant of the middle cerebral artery (MCA) that arises from either the proximal or distal portion of the A1 segment of the ACA, which runs parallel to the course of the MCA and supplies some of the MCA territory. We experienced a rare case of coexistence of PPOA with an unruptured aneurysm and accessory MCA. Three-dimensional computed tomographic angiography (3D-CTA) has an excellent picture of the spatial relationship of the surrounding bony and vascular structure.

Carotid Endarterectomy Using Lone Star Retractor System.

Cervical carotid disease is typical atherosclerosis, which is responsible for ischemic stroke. The effectiveness of carotid endarterectomy (CEA) for advanced carotid stenosis has been established in many large studies, and CEA is the gold standard in surgical treatment. On the other hand, endovascular carotid artery stenting (CAS) has become increasingly popular recently. It is very important to avoid any complications to maintain the effectiveness of CEA. The retractor device is important for the exposure of carotid arteries and for the safe surgical manipulation. We have started to use lone star retractor system (LSRS) to deploy the surgical field. LSRS provides the usability to handle and a shallower surgical field without the disturbance of surgical manipulation. And it can facilitate exposure of the distal internal carotid artery because surgeon can retract freely in whole circumference by towing with moderate strength. LSRS may bring the smoother and easier surgical manipulations in CEA.

Current status of a helicopter transportation system on remote islands for patients undergoing mechanical thrombectomy.

BACKGROUND: Mechanical thrombectomy (MT) is standard treatment for acute ischemic stroke (AIS) with large-vessel occlusion within 6 h of symptom onset to treatment initiation (OTP). Recent trials have extended the therapeutic time window for MT to within 24 h. However, MT treatment remains low in remote areas. Nagasaki Prefecture, Japan has many inhabited islands with no neurointerventionalists. Our hospital on the mainland is a regional hub for eight island hospitals. We evaluated clinical outcomes of MT for patients with AIS on these islands versus on the mainland. METHODS: During 2014-2019, we reviewed consecutive patients with AIS who received MT at our hospital. Patients comprised the Islands group and Mainland group. Patient characteristics and clinical outcomes were compared between groups. RESULTS: We included 91 patients (Islands group: 15 patients, Mainland group: 76 patients). Seven patients (46.7%) in the Islands group versus 43 (56.6%) in the Mainland group achieved favorable outcomes. Successful recanalization was obtained in 11 patients (73.3%) on the islands and 67 (88.2%) on the mainland. The median OTP time in the Islands was 365 min. In both the Islands and Mainland groups, the OTP time and successful recanalization were associated with functional outcome. The modified Rankin Scale (mRS) score at 90 days ≤2 was obtained in two patients and mRS = 3 in four patients among eight patients with OTP time >6 h. CONCLUSIONS: Few patients with AIS on remote islands have received MT. Although patients who underwent MT on the islands had longer OTP, the clinical outcomes were acceptable. OTP time on remote islands must be shortened, as this is related to functional outcome. In some cases with successful recanalization, a favorable outcome can still be obtained even after 6 h. Even if OTP exceeds 6 h, it is desirable to appropriately select patients and actively perform MT.

[Orbital Compartment Syndrome Perhaps Secondary to Intra-Orbital Fluid Retention and Orbital/Palpebral Emphysema Following Frontotemporal Craniotomy for an Unruptured Cerebral Aneurysm:A Case Report].

A 58-year-old woman underwent left frontotemporal craniotomy for clipping of an unruptured cerebral aneurysm. A small defect was accidentally created in the orbital roof intraoperatively. The patient developed left eyelid edema and ocular pain after recovery from anesthesia. The following day, the eyelid edema worsened, and she had difficulty opening her eyes. On the 9th postoperative day, she noticed diminished visual acuity and diplopia in her left eye when she was able to spontaneously open her eyes. Ophthalmological evaluation revealed mild left visual loss, decreased light reflex, ophthalmoplegia, ptosis, and chemosis. Computed tomography(CT)/magnetic resonance imaging revealed left proptosis, optic nerve stretching, intra-orbital fluid retention, and orbital/palpebral emphysema. She was diagnosed with orbital compartment syndrome(OCS)and received conservative treatment;however, her visual acuity did not improve. OCS observed after cerebral aneurysm surgery is rare;to date, only 24 cases have been reported in the available literature. Although the mechanism of OCS after craniotomy is unclear, it may be attributed to ocular compression by a muscle flap or increased intra-orbital pressure secondary to venous congestion. In the present case, the left superior ophthalmic vein and cavernous sinus were not clearly visualized on CT angiography. Therefore, we concluded that the right superior ophthalmic vein and superficial facial veins underwent dilatation and served as collateral circulation of the left orbital venous system. We speculate that OCS occurred secondary to increased intra-orbital pressure, possibly caused by inflow of cerebrospinal fluid with air into the orbit through a small bone defect that was accidentally created during craniotomy in a setting of orbital venous congestion.

[A Case of M2 Segment Dissection of the Middle Cerebral Artery Presenting with Deep White Matter Infarction Triggered by Minor Head Injury].

Herein, we report a rare case of a dissecting aneurysm of the M2 segment of the middle cerebral artery(MCA), presenting with a deep white matter infarction triggered by minor head injury. A 31-year-old woman was admitted to our hospital with headache and vomiting 3 hours after a mild head impact. A magnetic resonance angiogram obtained 10 months earlier, when the patient had complained of sudden headache, showed mild fusiform dilatation of the left M2 segment. On admission, computed tomography angiography(CTA)revealed irregular fusiform dilatation of the superior trunk of the left M2. Magnetic resonance imaging showed an intramural hematoma on the wall of the left M2 and acute infarction in the left deep white matter. Eight days after admission, CTA revealed further dilation of the aneurysm, and it was diagnosed as a dissecting aneurysm. The patient was successfully treated with proximal clipping and superficial temporal artery(STA)-MCA(M4)bypass on day 15. Bypass to a cortical M4 recipient was performed after the efferent M4 was identified using indocyanine green videoangiography. Four weeks postoperatively, the patient was discharged without any neurological deficits. The M2 dissecting aneurysm gradually regressed, and the bypass remained patent for 10 months postoperatively. To our knowledge, this is the first case of a dissecting M2 aneurysm treated by proximal clipping and STA-MCA bypass. This procedure seems a feasible option when the distal portion of the dissected MCA is difficult to expose.

[Early Development of a Symptomatic Expanding Porencephalic Cyst in the Hematoma Cavity after Subcortical Hematoma Removal in an Adult:A Case Report].

A 69-year-old woman presented on an emergency basis, with headache and left hemiparesis. Initial head CT at the time of admission revealed a large subcortical hematoma with perihematomal edema extending from the right parietal to the occipital lobe. A small part of the hematoma extended toward the trigone of the right lateral ventricle. CT angiography revealed no vascular abnormalities. Emergency craniotomy was erformed, and the patient's initial postoperative course was unremarkable. However, the patient's neurological symptoms worsened 10 days postoperatively, and CT revealed a new low-density cystic lesion with perifocal edema at the site of hematoma removal, in addition to severe cerebral compression. We performed a reoperation, and intraoperatively we observed hematoma fluid mixed with cerebrospinal fluid without any abnormal blood vessels or neoplastic lesions in the hematoma cavity. We identified the choroid plexus deep within the surgical field, and slight leakage of cerebrospinal fluid was detected from the ventricular aspect, indicating the formation of a small passage between the hematoma cavity and the ventricle. After the second operation, her postoperative course was uneventful without recurrent cyst formation. An early symptomatic expanding porencephalic cyst in the hematoma cavity after removal of an intracerebral hematoma is rare, and only a few cases have been reported in the literature. Based on literature review and considering the likely mechanism of cyst development, we speculated that progressive cyst expansion could be attributed to a check valve mechanism between the ventricle and the cavity from which the hematoma was removed, as observed in the present case.

[Ruptured Cerebral Aneurysm Associated with Arachnoid Cyst].

Cerebral aneurysms and arachnoid cysts are relatively common cerebral malformations and the use of recent modalities has increased their detection rates. However, cerebral aneurysms associated with arachnoid cysts are unusual. We describe two cases of ruptured cerebral aneurysms associated with arachnoid cysts. According to previous reports, clinical presentation may sometimes be unusual, as cysts can prevent subarachnoid hemorrhage. Moreover, in some cases, CT may reveal typical arachnoid cysts without subarachnoid hemorrhage, without intracystic hematoma, or with subdural hematoma alone. These clinical presentations and radiologic findings can lead to delayed diagnosis of subarachnoid hemorrhage. Therefore, we should consider the coexistence of arachnoid cyst in case of a warning sign of aneurysm rupture.

[Task-shifting Carried out by an Emergency Department's Stroke Hotline and Medical Care Support Conducted by Nurse Practitioners].

Our hospital serves as the main hub for eight remote island hospitals(RIHs)in Nagasaki Prefecture, Japan. The shortage of stroke physicians, which has led to overwork, is a major concern. Several "task-shifting" systems were adopted to avoid physician burnout. First, the emergency department established a hotline system for receiving emergency calls regarding a stroke, and which managed initial care until the stroke physicians arrived(called the Nagasaki Medical Center stroke hotline system: N-SHOT)in 2014. The rt-PA administration rate increased from 3.3% in the Pre-N-SHOT group to 6.7% in the N-SHOT group. Second, the 'isolated islands stroke hotline system(I-SHOT)', with which physicians in RIHs participate in cooperation with N-SHOT, was started in 2017. After I-SHOT was introduced, the number of patients treated with the drip and ship method using teleradiology and 24-h helicopter transportation increased from 20(2010-2016)to 29 cases in 2017-2018. Additionally, new information and communication technology(ICT)using smart devices was introduced into the teleradiology system for task support. Third, on behalf of stroke physicians, nurse practitioners(NP)helped bedridden patients who had been delivered from RIHs and who had received acute treatment, and returned to their islands by helicopter or airplane as transitions of care. N-SHOT is smoothly operated by each hospital department without reducing the quality of the stroke hotline. It has contributed to an increase in rt-PA and mechanical thrombectomy cases; I-SHOT has had the same effect. Task-shifting and task support with N- & I-SHOT, the smooth transfer system by NP, and the new ICT are considered to be useful for reducing the overall burden of stroke physicians.

[A Case of Radiation-induced Glioblastoma 29 Years after Treatments for Germinoma].

Intracranial germinomas are considered one of the most radiosensitive tumors and are curable by radiotherapy alone. Although patients can expect long-term survival, the adverse effects of radiotherapy and late sequelae in survivors are a major concern. Radiation-induced secondary neoplasms are one of those sequelae and are a serious concern because they are often connected directly with life prognosis. We describe a case of radiation-induced glioblastoma after radiotherapy for germinoma. An 11-year-old boy with basal ganglia germinoma was successfully treated with postoperative cranial irradiation. At the age of 40 years, he was admitted to our hospital for aphasia and memory disturbance. CT and MRI revealed a tumor in the left parietal lobe with dissemination. The tumor of the parietal lobe was removed surgically, and pathohistologically, it was diagnosed as glioblastoma. Long-term survivors who receive radiotherapy for germinomas in childhood are at risk for late complications, including radiation-induced neoplasms. Therefore, careful follow-up neurological examinations are recommended in these patients, even 20-30 years after radiotherapy.

[A Rare Case of Communicating Hydrocephalus with Intraparenchymal Pericatheter Cyst and Surrounding Edema in an Adult due to Accidental Change in the Pressure Setting of the Programmable Shunt System].

A 59-year-old woman suffering from memory impairment visited our hospital. She was discharged nine years ago without complications after undergoing neck clipping surgery for intracranial aneurysm rupture and a right ventricular peritoneal shunt using the CODMAN® HAKIM® programmable valve system(CHPV)for hydrocephalus. Initial CT/MRI revealed a cystic lesion with surrounding edema in the right frontal lobe around the proximal catheter, and a left frontal subacute subdural hematoma. The right ventricle was shown as a slit as before. The cystic portion presented with an MRI signal of the same intensity as the cerebrospinal fluid(CSF), and no enhancement effect was observed. It was thought to be a CSF cyst around the shunt catheter with interstitial CSF edema. Skull radiographs showed an accidental change in the CHPV pressure setting(100 to 190mmH2O), possibly due to head impact. We concluded that the newly set valve pressure caused sudden shunt dysfunction, resulting in CSF cyst formation and surrounding edema. Image findings and her symptoms were immediately improved on adjusting the shunt valve. This complication in adults associated with shunt dysfunction is very rare and only 10 cases have been reported to date. This is the first report of this complication due to an accidental reset of CHPV. To prevent the risk of misdiagnosing this condition as a tumor or abscess and performing unnecessary surgery, it is always necessary to suspect the possibility of this complication. For that purpose, detailed images, including diffusion-weighted images and contrast-enhanced MRI, should be done early in clinical practice.