Amide proton transfer MRI differentiates between progressive multifocal leukoencephalopathy and malignant brain tumors: a pilot study.

BACKGROUND: Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nerve system caused by the John Cunningham virus. On MRI, PML may sometimes appear similar to primary central nervous system lymphoma (PCNSL) and glioblastoma multiforme (GBM). The purpose of this pilot study was to evaluate the potential of amide proton transfer (APT) imaging for differentiating PML from PCNSL and GBM. METHODS: Patients with PML (n = 4; two men; mean age 52.3 ± 6.1 years), PCNSL (n = 7; four women; mean age 74.4 ± 5.8 years), or GBM (n = 11; 6 men; mean age 65.0 ± 15.2 years) who underwent APT-CEST MRI between January 2021 and September 2022 were retrospectively evaluated. Magnetization transfer ratio asymmetry (MTRasym) values were measured on APT imaging using a region of interest within the lesion. Receiver operating characteristics curve analysis was used to determine diagnostic cutoffs for MTRasym. RESULTS: The mean MTRasym values were 0.005 ± 0.005 in the PML group, 0.025 ± 0.005 in the PCNSL group, and 0.025 ± 0.009 in the GBM group. There were significant differences in MTRasym between PML and PCNSL (P = 0.023), and between PML and GBM (P = 0.015). For differentiating PML from PCNSL, an MTRasym threshold of 0.0165 gave diagnostic sensitivity, specificity, positive predictive value, and negative predictive value of 100% (all). For differentiating PML from GBM, an MTRasym threshold of 0.015 gave diagnostic sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 90.9%, 80.0%, and 100%, respectively. CONCLUSION: MTRasym values obtained from APT imaging allowed patients with PML to be clearly discriminated from patients with PCNSL or GBM.

Quantitative Chemical Exchange Saturation Transfer Imaging of Amide Proton Transfer Differentiates between Cerebellopontine Angle Schwannoma and Meningioma: Preliminary Results.

Vestibular schwannomas are the most common tumor at the common cerebellopontine angle, followed by meningiomas. Differentiation of these tumors is critical because of the different surgical approaches required for treatment. Recent studies have demonstrated the utility of amide proton transfer (APT)-chemical exchange saturation transfer (CEST) imaging in evaluating malignant brain tumors. However, APT imaging has not been applied in benign tumors. Here, we explored the potential of APT in differentiating between schwannomas and meningiomas at the cerebellopontine angle. We retrospectively evaluated nine patients with schwannoma and nine patients with meningioma who underwent APT-CEST MRI from November 2020 to April 2022 pre-operation. All 18 tumors were histologically diagnosed. There was a significant difference in magnetization transfer ratio asymmetry (MTRasym) values (0.033 ± 0.012 vs. 0.021 ± 0.004; p = 0.007) between the schwannoma and meningioma groups. Receiver operative curve analysis showed that MTRasym values clearly differentiated between the schwannoma and meningioma groups. At an MTRasym value threshold of 0.024, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive values for MTRasym were 88.9%, 77.8%, 80.0%, and 87.5%, respectively. Our results demonstrated the ability of MTRasym values on APT-CEST imaging to discriminate patients with schwannomas from patients with meningiomas.

A Spontaneous Extracranial Internal Carotid Artery Dissection with Autosomal Dominant Polycystic Kidney Disease: A Case Report and Literature Review.

Background and Objectives: Non-cystic manifestation of autosomal dominant polycystic kidney disease (ADPKD) is an important risk factor for cerebral aneurysms. In this report, we describe a rare spontaneous internal carotid artery (ICA) dissection in a patient with ADPKD. Observations: A 38-year-old woman with a history of ADPKD and acute myocardial infarction due to coronary artery dissection experienced severe spontaneous pain on the left side of her neck. Magnetic resonance imaging (MRI) revealed a severe left ICA stenosis localized at its origin. Carotid plaque MRI showed that the stenotic lesion was due to a subacute intramural hematoma. Close follow-up by an imaging study was performed under the diagnosis of spontaneous extracranial ICA dissection, and spontaneous regression of the intramural hematoma was observed uneventfully. Conclusions: When patients with a history of ADPKD present with severe neck pain, it is crucial to consider the possibility of a spontaneous ICA dissection. A carotid plaque MRI is beneficial in the differential diagnosis. Conservative management may benefit patients without ischemic symptoms.

Correction to: Intra-Arterial Transplantation of Low-Dose Stem Cells Provides Functional Recovery Without Adverse Effects After Stroke.

The original version of this article unfortunately contained an error in affiliation of Yuhtaka Fukuda.

[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.

[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.

[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.

[Significance of Existence and Future Prospects of Nurse Practitioners in Neurosurgical Teams].

Recently, hospitals and medical facilities have been experiencing a shortage of doctors along with heavy workload. The role of a mid-level provider may be important as a potential solution to these problems. A nurse practitioner(NP)is the most famous mid-level provider, and in our institution, the neurosurgery department has 3 NPs. Contrary to America, in Japan, the job of an NP is not an occupation independent from doctors or nurses. NPs perform 38 specific procedures according to doctors' instructions. Their activities include assisting with operations, writing prescriptions, participation in neurosurgical rounds and conferences, transportation of patients by helicopter, etc. The safe transportation of patients to isolated islands by a helicopter is especially a representative activity in our institution. Inclusion of NPs in clinical settings may bring forth medical improvements and superior work efficiency. According to regional characteristics, the job profile of a NP presents a potential scope for added capabilities.

[Aplastic or Twig-like Middle Cerebral Artery with Cortical Subarachnoid Hemorrhage and Reversible Cerebral Vasoconstriction Syndrome during the Postpartum Period in a Juvenile Female:A Case Report].

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.

[Perianeurysmal Edema:An Indirect Sign of a Minor Leak from an Intracranial Aneurysm].

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.

[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.

[A Pediatric Case of Clinically Mild Encephalitis/Encephalopathy with a Reversible Splenial Lesion(MERS)with Recurrent TIA-like Symptoms over a Prolonged Period].

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.

[Two Cases of Late-onset Brain Edema after Craniotomy for Unruptured Intracranial Aneurysms Suspected to be due to an Allergic Reaction to Arachnoid Plasty Material].

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.

[Endovascular Treatment of a Ruptured Aneurysm of the Right Vertebral Artery with an Aberrant Right Subclavian Artery].

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.

[Falx Meningioma Presenting with Intratumoral Hemorrhage and Interhemispheric Acute Subdural Hematoma:A Case of Report].

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.

[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.

[Reconsideration of Carotid Web and the Therapeutic Strategy].

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.

[A Rare Case of Spontaneous Thrombosis and Recanalization of a Ruptured Small Aneurysm in the Distal Posterior Inferior Cerebellar Artery].

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.

[Reversible Cerebral Vasoconstriction Syndrome with Cortical Subarachnoid Hemorrhage due to Acute Cortical Infarction Beneath the Sulcus:A Case Report].

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.