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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.

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.

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.

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.

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 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

A 68-year-old male with a sudden headache while defecation was transferred to our hospital. He was initially diagnosed with intracerebral hemorrhage in the right occipital lobe and acute subdural hematoma(ASDH)in the right interhemispheric fissure. A CT angiography(CTA)showed stenosis in the superior sagittal sinus(SSS)and the vein of Galen(VG)near the hematoma, which were considered to be due to compression of the hematoma. In the source image of CTA, the enhancement effect of the hematoma part was not clear. MRI revealed a heterogeneous mixed signal intensity in the hematoma area, suggesting a mixture of hematoma components that had bled at different times. Cerebral angiography performed two weeks after onset showed a tumor shadow imaged from the middle meningeal artery. Therefore, the presence of hemorrhagic meningioma was suspected. This was confirmed by contrast-enhanced MRI. One month after the onset, tumor resection was performed after the embolization of the feeding artery. Part of the tumor around the SSS and VG was left due to severe adhesion. Postoperatively, stenosis of the SSS and VG significantly improved. In this case, the increase in venous pressure may be related to the bleeding mechanism. Hemorrhagic onset meningioma with interhemispheric ASDH is extremely rare, and only 4 cases have been reported. It is easy to misdiagnose if only non-contrast CT is used. It should be noted that in cases of intratumoral hemorrhage, CTA may not show an enhancing effect in the acute phase. Since contrast-enhanced MRI may be useful for a definitive diagnosis, it should be performed at the time of initial imaging.

A 17-year-old female in a lethargic state with mild dysarthria was transferred to our hospital after experiencing a generalized tonic seizure immediately after giving birth. Head CT showed a cortical subarachnoid hemorrhage(cSAH)in the left frontoparietal convexity. Three-dimensional rotational angiography(3D-RA)revealed multifocal narrowing of the cortical branches of the left middle cerebral artery(MCA)and severe stenosis of the left M1 segment with plexiform collateral networks, suggesting the presence of reversible vasoconstriction syndrome(RCVS)and aplastic or twig-like MCA(Ap/T-MCA). When 3D-RA was repeated on day 17, the narrowing of the cortical artery had resolved, and a new constriction of more proximal blood vessels was observed. The arterial spasm disappeared within 3 months, confirming the diagnosis of RCVS and Ap/T-MCA. Although non-aneurysmal SAH due to Ap/T-MCA is extremely rare, RCVS often complicates cSAH in the frontal/parietal region. It is suggested that RCVS triggers cSAH in the presence of incidental Ap/T-MCA. Ap/T-MCA is thought to be caused by developmental abnormalities during the embryonic period, but only 11 cases in children or adolescents have been reported. This suggests that there are a considerable number of asymptomatic young patients whose condition has not been detected. The majority of patients with Ap/T-MCA are from East Asia, suggesting that racial and genetic background differences are a factor. As this anomaly is more likely to present as a stroke in adulthood, long-term follow-up is recommended if it is found at a young age. There is no evidence that revascularization is effective in preventing stroke. Further studies are needed on how to manage this condition appropriately.

We report a rare case of the endovascular treatment of a ruptured aneurysm of the right vertebral artery with an aberrant right subclavian artery(ARSA). A 60-year-old woman was urgently admitted because of consciousness disturbance. Brain CT showed subarachnoid hemorrhage, and CT angiography showed a right vertebral ruptured aneurysm. Endovascular treatment of the aneurysm was performed via a transfemoral approach. During the endovascular treatment, the right subclavian artery was found to diverge from the descending aorta on the periphery of the left subclavian artery. An ARSA was detected, and the right vertebral artery(VA)originated from the ARSA. The guiding catheter was passed through the right VA via an ARSA, and the aneurysm was completely embolized. The patient was transferred to another hospital on day 44 without any motor weakness. To our knowledge, this is the first case of an ARSA with a ruptured aneurysm in the right VA for which endovascular treatment was successfully performed via the ARSA. In patients with an ARSA or aberrant left subclavian artery, the artery could merge with Kommerell's diverticulum(KD)at its origin and be histologically fragile. Thus, in patients with an ARSA, attention should be paid to catheterization to avoid injuring the KD. CT angiography of the aortic arch might be considered before endovascular treatment.

We report two rare cases of late-onset brain edema after craniotomy for clipping or coating of unruptured intracranial aneurysms, possibly due to an allergic reaction to topically applied fibrin glue or gelatin sponge used for arachnoid plasty to cover the opened sylvian cistern. Both patients were women in their 60s with an allergic predisposition and both followed a similar clinical course. A slight fever and headache persisted during the postoperative period. Five to six weeks after surgery without complications, MR images showed an extensive T2 prolongated region in the white matter around the operative field, indicative of vasogenic edema, with mass effect and meningeal enhancement around the sylvian fissure that had been covered with gelatin sponge and sprayed fibrin glue. Swelling of the cerebral cortex around the sylvian fissure subjected to arachnoid plasty was also observed. Blood tests showed the absence of an inflammatory reaction and cerebrospinal fluid examination showed lymphocytosis that was considered to be due to an aseptic meningeal reaction or meningitis. Clinical symptoms and imaging findings steadily improved with the administration of steroids and antiallergic agents. Delayed brain edema may occur around the arachnoid plasty area despite an uneventful chronic postoperative period, which could be due to an allergic reaction to locally administered fibrin glue or gelatin sponge. Thus, the application of arachnoid plasty using fibrin glue and gelatin sponge in patients with a predisposition to allergies needs to be carefully considered.

We report a rare case of pediatric clinically mild encephalitis/encephalopathy with a reversible splenial lesion(MERS)associated with transient ischemic attack(TIA)-like symptoms. A 13-year-old boy who presented with transient left hemiparesis and dysarthria was transferred to our hospital. He had experienced similar symptoms at the age of nine years and was diagnosed with MERS type 2 due to the typical clinical course and MR imaging findings. His elder brother showed a similar clinical history at the age of eight years. DW-MR images on admission revealed high signal intensity areas in the splenium of the corpus callosum and deep white matter. The territories were depicted as low intensity on apparent diffusion coefficient maps and slightly high intensity on T2-weighted images. Recurrence of MERS type 2 was considered because the symptoms of the patient disappeared within several hours and the abnormal signal intensities markedly decreased on the follow-up DWI performed eight days after initial MR imaging. The abnormal MR imaging findings completely disappeared after five weeks. After discharge, the patient experienced eight TIA-like episodes with a similar clinical course and MR imaging findings over a period of six years. MERS associated with TIA-like episodes is extremely rare, especially MERS associated with recurrent episodes in multiple phases over a long period, as seen in the present case. In addition, the findings in the last two MR imaging scans involving the internal capsule, thalamus, and midbrain were highly unusual and maybe considered to be indicative of an advanced form of MERS type 2, as reported in other familial cases.

We report a rare case of perianeurysmal edema(PAE)around the dome of a usual intracranial aneurysm. A 79-year-old woman who presented with a dull headache that had become stronger from a month before was referred to our hospital for further examination of an aneurysm. MR angiogram had detected the aneurysm, having a dumbbell shape and arising from the M2 bifurcation of the right middle cerebral artery. Initial fluid attenuated inversion recovery and T2 weighed images revealed a slightly high intensity area in the brain around the dome of the aneurysm buried in the right temporal lobe, suggesting the presence of PAE possibly due to a preceding minor leak or partial thrombosis or impending rupture of the aneurysm. A CT angiogram revealed bleb formation of the aneurysm(size:10×6 to 4mm)without definite intraluminal thrombosis. The patient and her family consented to emergency craniotomy. During the microsurgical approach, thickening of the arachnoid membrane on the right sylvian fissure was observed. The subarachnoid space between the right frontal and temporal lobes was turbid/adhesive, and deposition of hemosiderin was observed around the aneurysm, indicating a preceding minor bleeding. The aneurysm was successfully clipped, and the postoperative course was uneventful. The present case showed that PAE could be observed even in a usual aneurysm. This finding might be an indirect sign of a preceding minor leak from the aneurysm, particularly when the dome is buried in brain parenchyma or is in close contact with the surrounding brain surface.

We report a rare case of reversible cerebral vasoconstriction syndrome(RCVS)with cortical subarachnoid hemorrhage(cSAH)associated with a fresh cortical infarction beneath the sulcus with thick cSAH. A 34-year-old woman presented with history of thunderclap headache. She was transferred to our hospital for further examination of a cSAH in the left frontal lobe. Results of the cerebrospinal fluid examination were unremarkable, but three-dimensional rotational angiography revealed multiple instances of narrowing of the cortical branches of the anterior and middle cerebral arteries, suggesting the diagnosis of RCVS. Diffusion weighted imaging(DWI)demonstrated a small cortical area with high-signal intensity around the sulcus , where a thick cSAH clot was observed. This cortical lesion appeared as low-signal intensity on the apparent diffusion coefficient maps, and the follow-up T2-weighted images(obtained 3 months after onset)demonstrated a residual lesion that was smaller than the initial DWI abnormality with high-signal intensity;thus indicating the presence of a coincident fresh cortical infarction. The position of the infarct next to the thickest portion of cSAH suggested that it was the bleeding source of the cSAH. Ten days after onset, the cerebral blood flow and volume in the cortex around the cSAH increased as compared to the same area on the contralateral side. These findings suggested that at least one of the bleeding mechanisms of the cSAH was related to the hemorrhagic infarction or subpial hemorrhage resulting from the "ischemia-reperfusion injury" due to the acute disturbance of the pial vessel microcirculation with subsequent rapid resolution of the blood flow during the early phases of RCVS. These dynamics could not be demonstrated with contemporary angiographic imaging.

We report an extremely rare case of dural arteriovenous fistula(DAVF)involving the superior sagittal sinus(SSS)that presented as a primary intraventricular hemorrhage(PIVH). A 79-year-old man who presented with disturbance of consciousness and vomiting was transferred to our hospital. The initial head CT revealed an intraventricular hemorrhage in the lateral, third, and fourth ventricles, predominantly involving the right lateral ventricle associated with obstructive hydrocephalus. CT angiography and three-dimensional rotational angiography(3D-RA)revealed SSS-DAVF with retrograde venous drainage from the cortical venous system to the subependymal venous system through engorged superficial/anastomotic/deep medullary or transcerebral veins, showing a pseudophlebitic pattern. A severe stenosis of the SSS was observed at the site just proximal to the shunting point. A varix of the right transvers caudate vein(TCV)was observed within the thickest portion of the hematoma in close contact with the wall of the right lateral ventricle. A stenosis of the branching point of the right TCV was detected on the 3D-RA image. The DAVF was completely cured after transarterial embolization. The varix gradually shrank and finally disappeared after 2 months. This is the first report of a case of PIVH due to SSS-DAVF with a subependymal varix considered as the bleeding point. Serial gadolinium-enhanced MR images clearly showed the shrinking of the varix. Our case is the second reported case of spontaneous resolution of the varix after embolization of the DAVF. The obstructive changes of the two venous outflow pathways(SSS/TCV)might further worsen the state of venous congestion in the deep medullary venous system and eventually lead to formation and rupture of the varix.

The incidence of spontaneous thrombosis of intracranial aneurysm ranges from 1% to 2% of ruptured aneurysms. Most of them are giant or large aneurysms, and various factors have been discussed in previous literatures. Recanalization of thrombosed aneurysms may be rare, but its mechanism is poorly understood. Reports on recanalization of small aneurysms after spontaneous thrombosis are rare, and the natural history is still unknown. We describe a rare case of spontaneous thrombosis and recanalization of a ruptured small aneurysm of the distal posterior inferior cerebellar artery. Spontaneous aneurysmal thrombosis should not always be considered as a good or safe sign, as it may recanalize in a short time, resulting in re-rupture. In the acute stage, periodic follow-up of patients with a spontaneously thrombosed aneurysm is important.

The term "carotid web" was first used in 1973 and is considered a rare form of fibromuscular dysplasia(FMD). A carotid web was reported to produce thrombus formation and cause of ischemic events. However, it is rarely reported because of its low incidence. As for the diagnosis, noninvasive routine radiological modalities such as ultrasonography or magnetic resonance angiography may have very low sensitivity due to the subtle nature of the entity. Therefore, these types of lesions may be often underdiagnosed. We describe three cases that presented with minor and recurrent major ischemic strokes resistant to medical management. All 3 cases had a good course with no recurrence after carotid endarterectomy. On pathological examination, all specimens revealed mild atherosclerotic change, although FMD was known to be a non-inflammatory and non-atherosclerotic angiopathy. Early detection of a carotid web is highly important. Three-dimensional CT angiography(3D-CTA)maximum intensity projection(MIP)imaging seems to be a reliable noninvasive technique, although catheter angiography is considered as the gold standard. The cases with carotid web have characteristics such as more recurrent ischemic stroke and resistance to medical management. Surgical treatment should be considered if medical management in unsuccessful. Moreover, even if asymptomatic, it might also be considered for cases with a growing web or with blood stasis behind the web.

We report an extremely rare case of a fenestration in the infracallosal(A2)segment of the right anterior cerebral artery(ACA)associated with an unruptured aneurysm at the proximal end of the fenestrated portion. A 70-year-old man was referred to our hospital for further examination and treatment of unruptured aneurysms at the A1/A2 junction of the right ACA and the distal end of the right vertebral artery that were incidentally detected on MR angiography. CT angiography and 3D-rotational angiography revealed a fenestration in the proximal A2 segment of the right ACA with a small(3.6×3.8mm)aneurysm arising from the proximal end of the fenestration. The dome of the aneurysm projected to the left anterior/inferior direction. He underwent aneurysm neck clipping surgery via the right pterional approach without complications, while the vertebral artery aneurysm was managed conservatively. An extensive review of the literature revealed that only a small number of cases of A2 fenestration have been reported to date. To our knowledge, this is the first report of an A2 fenestration associated with an aneurysm at the fenestrated segment. Embryologically, the A2 fenestration may represent a remnant of plexiform arterial channels that constitute the primitive ACA system including the primitive olfactory artery, median artery of the corpus callosum and anterior communicating plexus.

We report an extremely rare case of a fenestration in the cavernous segment of the left internal carotid artery(ICA)associated with an unruptured aneurysm at the proximal end of the fenestrated portion. A 44-year-old woman with a dull headache was referred to our hospital for further evaluation of a suspected aneurysm in the right ICA on MR angiography(MRA). CT angiography and 3D-rotational angiography revealed no aneurysm in the right ICA;however, an intracavernous fenestration with an incidental aneurysm was observed in the left ICA. The aneurysm was small(5×3mm)with a wide neck arising from the origin of the ventral limb of the duplicated vessels, in association with a tiny bulge projecting medially. She requested conservative management and periodic follow-up with MRA. After 18 months, no structural change in the aneurysm was observed. To our knowledge, including our patient, only three cases of this type of ICA fenestration have been published, and this is the first report of an ICA fenestration with an unruptured aneurysm at the fenestrated segment. It is presently unknown whether the intracavernous fenestration has the potential to form an aneurysm within the proximal end of the duplicated segment, as reported in cases of supraclinoid ICA fenestrations.

We report a rare case of an unruptured aneurysm arising from the junction between the internal carotid artery(ICA)and duplicate origin of the middle cerebral artery(MCA). A 49-year-old man who presented with vertigo was admitted to our hospital. Subsequent MR and CT angiograms revealed an incidental aneurysm arising from the proximal end of the duplicate origin of the left MCA. He underwent clipping via the distal transsylvian approach. The aneurysm projected to the posterior direction and several perforators from the two M1 segments were attached to the neck of the aneurysm, which made neck dissection very difficult. Approaching the space from the posterior/lateral direction to reach the M1 segment, the aneurysm neck was successfully dissected and clipped without sacrificing any perforators or stenosis of parent vessels. The postoperative course was uneventful, and the patient was discharged within 2 weeks. Duplicate origin of the MCA has been confused with a fenestration of the proximal M1 segment or terminal segment of the ICA. In this condition, two MCA branches arise separately from the terminal segment of the ICA and fuse early to form an arterial ring at the proximal M1 segment. An aneurysm originating from this anomaly has never been described. However, some aneurysms associated with this type of origin may have incorrectly been reported as those associated with proximal MCA or terminal ICA fenestrations. We summarize the cases that are similar to our case of duplicate origin of the MCA with an aneurysm, and discuss the precise diagnosis and significant intraoperative problems that were described in the literature.

Distal anterior cerebral artery(DACA)aneurysms have a low incidence. Particularly, DACA mirror aneurysms are extremely rare, although DACA multiple aneurysms are not rare. Generally, it is said that tiny aneurysms have a low risk of rupture. However, we sometimes encounter cases of ruptured tiny aneurysm. We describe a rare case of a mirror image of DACA ruptured tiny aneurysm. A tiny aneurysm can rupture if the aneurysmal wall is fragile. Detection of the aneurysm may often be difficult with a single modality, even if the modality is digital subtraction angiography. Moreover, the distribution of subarachnoid hemorrhage may not be typical. It might be important to capture a slight change of aneurysm in follow-up imaging to detect a ruptured aneurysm over multiple iterations of imaging.

We report a rare case of a de novo ruptured aneurysm arising from the twig-like networks(TLN)of an anomalous collateral artery associated with an aplastic or twig-like middle cerebral artery(Ap/T-MCA). A 65-year-old woman with a decreased level of consciousness, who had been diagnosed with a right Ap/T-MCA and was treated with coil embolization for a ruptured A1 aneurysm at the origin of the anomalous collateral artery 4 years ago, was transferred to our hospital. Head CT revealed an intracerebral hematoma extending from the right frontal lobe to the caudate nucleus with intraventricular hemorrhage. Subsequent 3D-rotational angiograms revealed a ruptured de novo aneurysm arising from the TLN and regrowth of the residual neck of the coiled aneurysm. The two aneurysms were successfully treated by surgical clipping combined with superficial temporal artery middle cerebral artery anastomosis in the subacute phase. To our knowledge, only 11 cases of this type of aneurysm have been reported, including our case, and this is the first report of a de novo aneurysm within the TLN so far. Although all previously reported aneurysms were small(5-6mm), 10 of them(91%)ruptured. These data may indicate the vulnerability of this type of aneurysm to rupture despite their small size, probably due to hemodynamic stress and the fragile nature of their immature walls. To prevent recurrence of hemorrhage in these cases, revascularization may be necessary in addition to surgical clipping. Whether this concept is correct is an open question. Further studies are necessary to examine this issue.

A 65-year-old woman was transferred to our hospital because of loss of consciousness along with a right hemiplegia due to an intracerebral hematoma(ICH)that extended from the left temporal lobe to the lateral part of the basal ganglia. CT angiograms(CTA)and 3D-rotational angiograms showed an absence of the distal C1 segment of the left internal carotid artery(ICA), and an anomalous collateral vessel arising from the proximal end of the left A2 with plexiform(twig-like)arterial networks, supplying antegrade blood flow to the left middle cerebral artery territory. The caliber of the left carotid arterial system decreased from the origin to the terminal end. The source images of CTA revealed that the plexiform arteries were very close to the ICH, suggesting that the vessels might have caused the bleeding. Because a hypoplastic left carotid canal was observed, the segmental dysgenesis of the C1 portion of the left ICA seemed to have occurred during the early embryonic period. T2-weighted DRIVE images of MRI demonstrated the presence of a cord-like rudimentary structure corresponding to the distal C1 and proximal M1 portions. The patient was managed conservatively and was transferred to another hospital for subsequent rehabilitation. Segmental dysgenesis of the C1 portion is extremely rare. To our knowledge, only a single report has been published. The present findings suggest that 1)an anomalous collateral vessel corresponding to Heubner's artery evolved with residual primitive plexiform(twig-like)arterial networks and 2)this anomalous structure has not been proposed as a type of collateral systems for ICA dysgenesis.

We report the first case of two de novo miniature aneurysms(ruptured/unruptured)emerging from the infundibular dilatation(ID)of the callosomarginal artery, which branches from the infracallosal(A2)segment of the azygos anterior cerebral artery(AACA), in a 36-year-old woman. The patient had previously been diagnosed with a miniature, unruptured aneurysm, occurring in the A2 segment of the AACA, detected by CT angiography(CTA)at another hospital two years ago, and had been followed up with MR angiography(MRA)every 6 months. Three months after the final check-up with MRA, which did not indicate a significant change in the aneurysm, the patient presented with subarachnoid hemorrhage. Subsequent CTA and digital subtraction angiograms revealed that the right callosomarginal artery, originating from the apex of the aneurysmal bulge, had a maximal diameter of 3mm, indicating an ID of the artery. Additionally, two miniature bleb-like aneurysms emerged from the ID, projecting in opposite directions:one projecting to the right-posterior/superior direction and the other to the left-anterior/inferior direction. Both aneurysms were successfully clipped via a right pterional approach with partial resection of the gyrus rectus, and the right-projecting aneurysm was confirmed to be ruptured during surgery. In the current report, we review previously reported cases of AACA with aneurysms, and discuss their clinical characteristics, and the possible mechanisms underlying the formation of the ID and de novo aneurysms in this extremely rare case.

A 55-year-old man presented with difficulty breathing, chest pain, and disturbance of consciousness, and was transferred to our hospital. Initial whole body CT revealed a diffuse subarachnoid hemorrhage(SAH)with severe pulmonary edema that was considered neurogenic in origin. He received controlled ventilation under sedation and conservative care for the SAH. One day after the onset of the SAH, his left pupil suddenly became dilated to 6mm, with no reaction to light. Head CT showed no new bleeding. Subsequent CT angiogram revealed a right internal carotid-posterior communicating artery aneurysm(IC-PC AN)with a posterior-lateral projection; however, no vessel abnormality was observed in the left anterior or posterior circulations. The aneurysm was successfully treated with coil embolization. We reviewed reported cases of isolated oculomotor nerve palsy(ONP), without direct compression by ruptured aneurysms, and found that only 11 cases exist, including our case. Interestingly, six of them were associated with anterior communicating artery aneurysms. A mass effect, chemical stimulation, and a jet stream of blood were proposed as the mechanisms of this rare type of ONP, in addition to the specific neurovascular relationships between the oculomotor nerve and the posterior cerebral/posterior communicating/superior cerebellar arteries, with abnormal nerve contact or compression. Though rare, ruptured IC-PC ANs could cause contralateral ONP; other types of ruptured aneurysms may also lead to indirect effects on nervous structures without direct compression. This type of rare presentation of ruptured aneurysms should be considered, especially in cases of multiple aneurysms, such as IC-PC ANs.

A 69-year-old woman was admitted to our hospital because of a sudden severe headache without a history of head trauma. CT and MRI revealed an acute subdural hematoma (ASDH) extending from the right interhemispheric space to the posterior fossa bilaterally, with a small amount of subarachnoid hemorrhage that was predominantly localized to the left side of the basal cistern. CT angiogram demonstrated a long protruding ruptured aneurysm at the junction of the right internal carotid and posterior communicating arteries (IC/PC AN) with a posteroinferior projection, associated with a small bleb located near the tentorial edge close to the ipsilateral posterior clinoid process, for which she received clipping surgery. Though rare, IC/PC AN could cause pure or nearly pure ASDH in the above-mentioned distribution. Therefore, in patients with such ASDH, especially without a history of head injury or precise information regarding the situation at the time of onset, urgent imaging evaluation and early intervention are essential to prevent devastating re-rupture events.

Here we report a case of radiation-induced carotid stenosis treated with carotid artery stenting and proximal and distal protection. A 62-year-old man with a history of radiation therapy for cervical malignant lymphoma at 31 years of age was diagnosed with left radiation-induced carotid stenosis. Angiography revealed left common carotid artery severe stenosis, and T1-weighted magnetic resonance imaging showed plaque hyperintensity. He was treated with carotid artery stenting and proximal and distal protection. Postoperative carotid ultrasonography showed moderate dilatation of the left common carotid artery and his postoperative course was uneventful. Carotid artery stenting and proximal and distal protection for radiation-induced carotid stenosis may be an effective treatment.

To evaluate the relationship between preoperative analysis of platelet aggregability and perioperative complications, we analyzed 42 patients who underwent carotid endarterectomy or carotid artery stenting. The effect of antiplatelet drugs was tested by whole blood aggregometry. ADP (adenosine-diphosphoric acid) and collagen were used as agonists. According to platelet aggregability, patients were classified into 4 groups (class A: highly inhibited, class B: moderately inhibited, class C: normally inhibited, class D: non-inhibited). Seven (32%) of 22 patients were stratified as clopidogrel nonresponders, whereas four (10%) of 40 patients were aspirin nonresponders. Hemorrhagic complications were registered in four patients. All of them were classified as class A. Ischemic complications occurred in two patients, one was classified as class C, the other was class D. Preoperative analysis of platelet aggregability could be useful to reduce the risk of perioperative complications after carotid surgery.

Remote cerebellar hemorrhage (RCH) following spinal surgery is extremely rare. We present two cases of RCH following cervical spinal surgery. The first case is a 71-year-old female. She underwent surgery for atlantoaxial subluxation and a subcutaneous suction drain was placed. Three hours after surgery, she became comatose and computed tomography (CT) revealed RCH. The second case is a 51-year-old female. She underwent surgery for ossification of posterior longitudinal ligament in the cervical spine. Intraoperatively, the dura was opened unintentionally and a subcutaneous suction drain was placed. She complained of a severe headache and nausea postoperatively, and CT obtained two days after the surgery demonstrated RCH. In both cases, drains contained much fluid, which was assumed to be consistent with cerebrospinal fluid. Both cases were managed conservatively and displayed no cerebellar symptoms on discharge. Rapid loss of a great amount of cerebrospinal fluid might be the causative factor of RCH. RCH might occur after any type of spinal surgery with dural tear or intradural manipulation. Early diagnosis is particularly important for the treatment of RCH following spinal surgery and spinal drainage might be useful to manage cerebrospinal fluid leakage.

We report a rare case of a vertebral arteriovenous fistula presenting with subarachnoid hemorrhage (SAH). A 60-year-old man was admitted to our hospital with a sudden onset of headache and neck pain. A neurological examination showed no abnormalities. Computed tomography scans revealed SAH in the pontine cistern and cistern magna. Although the first cerebral angiogram failed to depict the cause of bleeding, the second angiogram on day 15 demonstrated an arteriovenous fistula in the left vertebral artery at C4-5, which was draining into the internal vertebral venous plexus and forming a venous pouch. The fistula was successfully obliterated by transarterial embolization using detachable platinum coils. In patients with SAH with predominance in the posterior fossa, attention should also be paid to spinal vascular lesions. Three-dimensional digital angiography and digital subtraction angiography allow a reliable visualization of such lesions.

The SAPPHIRE trial has established carotid artery stenting (CAS) in high-surgical-risk patients as an effective alternative to carotid endarterectomy. Since the occurrence of distal embolization with CAS is still a major concern, an embolus protection device is usually employed during the procedure. Although the advantage of the filter device is continuation of blood flow during the procedure, blood flow is occasionally reduced due to plaque debris or thrombus. Here, we report a case of internal carotid artery (ICA) stenosis complicated with filter obstruction during CAS. A 74-year-old woman who had a history of coronary artery stenting was referred to our hospital for the treatment of carotid artery stenosis. Angiography showed occlusion of the right ICA and high-grade stenosis at the origin of the left ICA. Since cerebral circulation was impaired significantly in the left cerebral hemisphere, CAS was performed for the left ICA stenosis using an embolus protection filter. Self-expandable stent was placed into the left ICA following predilation. The patient developed consciousness disturbance and right hemiparesis during postdilation. Angiography showed impairment of blood flow, indicating filter obstruction. The debris containing blood stasis was removed with an aspiration catheter and the flow was restarted retrieving the filter. The symptom recovered within one hour. Appropriate antithrombotic therapy and preparation for filter obstruction such as the provision of an aspiration catheter are important in CAS using an embolus protection filter.

Despite advances in surgical techniques and improvements in perioperative care, the incidence of perioperative strokes has not decreased, reflecting the aging of the population and the increased number of patients with complication. We investigated the cases who were consulted due to perioperative stroke. From April, 2004 to March, 2007, a total of 102 patients were referred for neurological evaluation because of perioperative stroke. Types of planned or performed surgery, risk factors, types of stroke and timing of the events were analyzed. Sixty-seven cases were consulted preoperatively for history or risk factors of stroke. Forty-seven cases had ischemic risk factors and cerebral vascular recanalization was carried out in four patients who experienced severe cerebral hypoperfusion. The other patients with ischemic risk factors were treated to avoid dehydration or hypotension perioperatively. Nine cases with hemorrhagic risk factors, such as cerebral aneurysm, were treated to avoid significant hypertension during surgery. The types of planned surgery were cardiovascular surgery in 29 cases, abdominal surgery in 13, cervical surgery in 7, and thoracic surgery in 6. Except for one case, who suffered cerebral embolism due to cardiac surgery, those who were consulted preoperatively did not experience stroke. Neurological events had occurred in 35 patients and they were consulted postoperatively. The surgical procedures were cardiovascular surgery in 19 patients, thoracic surgery in 6, abdominal surgery in 6. The types of stroke were cerebral infarction in 20 cases, hypoxic brain in 8, and transient ischemic attack in 5. The cause of the cerebral infarction was considered as cerebral embolism in 19 cases. Those who were consulted preoperatively were treated to prevent intraoperative stroke and did not suffer neurological complication. Most stoke in patients undergoing surgery were not related to hypoperfusion but due to embolism.

We described a case of endoluminal stent placement for cervical internal carotid artery stenosis in which access was obtained via the proximal portion of the right radial artery. A 70-year-old man with a history of arteriosclerosis obliterans presented for endoluminal revascularization of a stenosed left internal carotid artery. The transfemoral approach was not possible because of severe atherosclerosis of the bilateral common iliac arteries. An approach was attempted via the right radial artery. After placement of a 6F short sheath in the proximal portion of the right radial artery, the guiding catheter was positioned in the left common carotid artery using the coaxial catheter system. Stenting was successfully performed under distal protection. This novel approach should be considered for endovascular procedures for which access to the carotid artery is limited.

Retrograde cannulation of the superior ophthalmic vein (SOV) is an important route for embolization of cavernous sinus dural arteriovenous fistula (dAVF). We encountered two cases with significant difficulties with cannulation of the SOV. A 66-year-old woman and an 83-year-old woman were referred to our hospital for treatment of cavernous sinus dAVF. Unilateral chemosis and exophthalmos were seen in both patients. At first, transarterial embolization was performed to reduce the flow, then, transvenous embolization was employed for the treatment of cavernous sinus dAVF. The attempts to embolize through a transfemoral route failed owing to a thrombosed or compartmentalized cavernous sinus. Surgical exposure of the SOV and puncture with needle-cannula was tried. However, in both cases, unsuccessful cannulation resulted in uncontrollable bleeding and periorbital swelling. Finally, by using road-mapping SOV was punctured in the deeper part and the fistula was obliterated with detachable coils. Postoperative course was uneventful and their symptoms were improved. Although the SOV is a useful route for cavernous sinus dAVF embolization, the presence of narrowed or tortuous veins can preclude successful cannulation.

Three cases of internal carotid artery (ICA) dissection due to trivial trauma were reported. A 14-year-old, previously healthy, girl developed left hemiparesis after jogging. MRI sh owed cerebral infarction in the right basal ganglia and the MR angiography (MRA) revealed luminal narrowing of the right ICA as well as pseudolumen at the origin of the right ICA. She was treated with antithrombotic therapy. Follow-up MRA demonstrated normal signal in the right ICA. A 23-year-old woman admitted to the hospital because of minor facial injury due to a traffic accident. Although she had no apparent symptom, follow-up CT, one day after presentation,. showed cerebral infarction in the right basal ganglia. Angiography showed diminished luminal diameter of the right ICA. She was treated with antithrombotic therapy and follow-up angiography showed reconstitution of normal lumina of the right ICA. A 34-year-old woman was referred to our hospital because of transient ischemic attack following swimming. Neurological examination was normal and MRI did not show any ischemic lesion. MRA revealed diminished signal in the left ICA as well as string and pearl sign at the origin of the left ICA. She was treated with antithrombotic therapy, and follow-up angiography showed normalization of the left ICA. Cervical ICA dissection due to trivial trauma usually appears as an eccentric tapered stenosis arising at the origin of the ICA and resolves with complete or excellent recovery in most cases. Surgical or endovascular treatment should be reserved for patients who have persistent symptoms of ischemia despite adequate antithrombotic treatment.

Placement of a stent over the aneurysm neck and secondary coil embolization prevents coil migration and allows attenuated packing of the coils. However, during the course of the embolization, coils project over and obscure the parent vessel. Here we report a novel technique for endovascular parent vessel reconstruction with aneurysm embolization. A 73-year-old male had an incidental fusiform aneurysm at the V4 segment of the left vertebral artery. The size of the aneurysm increased from 7 mm to 8 mm in diameter. Since the right vertebral artery was hypoplastic, endovascular parent vessel reconstruction with coil embolization was performed. A flexible balloon-expandable coronary stent was navigated to the lesion and deployed successfully followed by coil embolization using a microcatheter through the stent. The balloon was inflated intermittently during coil insertion avoiding coil migration to inside the stent. Furthermore, the angle of the image intensifier was manipulated to visualize the inside of the stent. Postoperative course was uneventful and follow-up MRI three moths later demonstrated obliteration of the aneurysm and patency of the parent artery. This technique provides a practical treatment strategy for the management of a circumferential aneurysm.

Although dissecting aneurysms appear not to be as rare as previously reported, their etiology remains unclear. We describe a rare case of a girl with ischemia in the region of the posterior cerebral artery (PCA). The patient complained of a mild headache and left upper paresthesia. Neurological findings revealed a mild left hemiparesis. Visual field was intact, and cardiac embolism was excluded due to the almost normal chest X-p, ECG, and UCG. Laboratory findings were within normal limits. However, MRA and angiography revealed a linear shadow and an irregular caliber change at the right P1-P2 segment. Conservative therapy was pursued and the patient showed full neurological recovery. After a 3-month follow-up period, MRI showed no recurrence and MRA showed that the lesion had returned to normal. Here, we report the case as well as review the literature relating to this disorder, including discussion of its etiology, clinical features, radiological findings, and management strategies. We conclude that this disorder should be taken into consideration as a differential diagnosis of cerebrovascular disease in young people.