Diffusion-weighted imaging (DWI) allows determination of the extent of cerebral ischemia and the distribution of tissue damage from the hyperacute stage and is widely used to diagnose and plan treatment for acute stroke. Although diffusion-perfusion mismatch (DPM) has garnered attention as a method for determining the indications for thrombolytic therapy in acute stroke patients, time is required to evaluate blood flow using perfusion imaging, and only relatively few facilities are currently able to use this method. In recent years, clinical-DWI mismatch (CDM), representing a combination of clinical severity and DWI findings, and magnetic resonance angiography-DWI mismatch (MDM), as a combination of the presence or absence of major arterial lesions and DWI findings, have been investigated as alternatives to DPM for determining the indications for thrombolytic therapy in acute stroke patients. We reviewed the utility of MRI-DWI in acute stroke patients, with a focus on DPM and MDM.

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The Eustachian valve (EV) is an embryological remnant of the inferior vena cava (IVC) valve thatprenatally directs the oxygenated blood from the IVC across the patent foramen ovale (PFO) into systemic circulation. Even when the EV is prominent, it is usually considered to be a benign finding in the absence ofassociated cardiac anomalies. We present a patient with PFO whose prominent EV increased spontaneousright-to-left shunt and promoted paradoxical cerebral embolism. EVs may persist more frequently than expected in Japan and should be considered adjunctive risk factors for paradoxical cerebral embolismirrespective of their size in patients with PFO.

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Sleep-disordered breathing (SBD) has been reported to be a risk factor for cerebrovascular disease. We investigated the frequency of SDB in Japanese patients with acute cerebrovascular disease and the associated factors. Between May 2010 and January 2011, we prospectively enrolled 140 patients (85 males; mean age, 72.6 years) with cerebrovascular disease within 24 hours of onset and evaluated SBD within 7 days after admission. SBD was defined as respiratory disturbance index (RDI) ≥ 5. Patients were divided into 4 groups according to the RDI value as follows: < 5 (none), 5-14 (mild), 15-29 (moderate), and ≥ 30 (severe), and the factors associated with SDB were investigated. The mean time from admission to the sleep study was 4.6 days. The mean RDI was 23.8±18.2. SDB was observed in 125 patients (89%). Frequencies of SDB by cerebrovascular disease type were as follows: 17/20 patients (85%) with TIA, 83/94 patients (88%) with ischemic stroke [7/7 patients (100%) with large artery atherosclerosis, 12/12 patients (100%) with small vessel occlusion, 30/33 patients (91%) with cardioembolism, 34/42 patients (81%) with other/undetermined causes of stroke], and 25/26 patients (96%) with intracerebral hemorrhage. The percentage of severe SDB (RDI ≥ 30) in each group was as follows: 20% in the TIA group, 32% in the stroke group [71% in the large artery atherosclerosis group, 36% in the cardioembolism group, 25% in the small vessel occlusion group, 24% in the other/undetermined cause of stroke group], and 41% in the intracerebral hemorrhage group. The patients with more than 3 vascular risk factors were more frequently in the severe SDB group than in other groups (p=0.0052). SBD was frequently complicated in the cerebrovascular disease patients. In conclusion, Japanese patients with acute cerebrovascular disease should be assessed for SDB regardless of obesity and severe stroke.

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This report describes 2 patients with intramedullary cavernous hemangiomas who experienced intramedullary hemorrhage. A 72-year-old man presented with muscle weakness and sensory disturbance of the left proximal lower extremity and hyperreflexia of the left patellar tendon. MRI imaging revealed an intramedullary hemorrhage at Th9-10 and a cavernous angioma at Th11. The cavernous angioma was removed on day 39. His lower-extremity neurological function improved immediately after surgery. A 65-year-old woman complained of upper-extremity, chest, and back pain. Subsequent MRI imaging showed an intramedullary hemorrhage at C6-Th4 and a cavernous angioma at Th1. She was managed conservatively because she had no neurological deficit. Optimal management must be conducted for each case of intramedullary cavernous hemangioma.

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A 22-year-old man without significant past medical history noticed a right occipital headache, paresthesia of the right side of the body including the face, and right-upper homonymous quadrantanopsia after sexual intercourse. Brain MRI showed acute infarctions in the right occipital lobe and thalamus. MRA revealed a pearl-and-string sign in the right posterior cerebral artery. He was diagnosed as having cerebral infarctions due to a postcoital posterior cerebral artery dissection and was treated with aspirin. His clinical course was uneventful, and the irregularity of his right posterior cerebral artery was improved in an MRA image one year after the onset. Cerebral artery dissection is an important cause of cerebral infarction in the young, and sexual intercourse can trigger it. Therefore, it is important to take a history carefully when you suspect a young patient of having a cerebral artery dissection. And in general, a benign nonorganic headache related to sexual intercourse is known as a primary headache associated with sexual activity, but we should take into account that cerebral artery dissection can be a cause of headache related to sexual intercourse.

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A 76-year-old woman presented with left hemiparesis and mild neck pain and was admitted to another institution. In the institution, a brain CT scan was performed to find intracranial lesions, and it did not detect any, including intracerebral hematoma. Based on the clinical symptoms and a CT scan negative for hemorrhagic stroke, she was initially diagnosed as having had an acute ischemic stroke. A few hours later, her symptoms developed into left-side-dominant tetraparesis, and brain MRI was performed. Although the MRI scan could not detect any abnormal lesions in the brain, she was suspected to have an ischemic lesion of the brain stem and was referred to our institution on the next day of deterioration. When she was admitted to our department, she complained of strong pain and a tingling sensation in the left shoulder. A lesion of the cervical cord was suspected, and an MRI scan of the cervical spine was performed. The scan revealed a left-side-dominant dorsal epidural hematoma from the C3 to Th1 level, and emergency surgery was performed to remove the hematoma. The neurological condition of the patient improved minimally after the operation. Although it has rarely been emphasized before, cervical epidural hematomas can cause hemiparesis and should be considered in the differential diagnosis of ischemic cerebrovascular accidents.

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We report a case of a non-traumatic dissecting aneurysm of the A1 anterior cerebral artery (ACA) with a subarachnoid hemorrhage. A 51-year-old man lost consciousness with acute onset and was sent to our hospital. CT, MRI/MRA, and cerebral angiography showed a left A1 ACA dissecting aneurysm. Trapping of the aneurysm was performed using a left front-temporal craniotomy, and the patient made a good recovery. We consider recent treatment for A1 ACA dissecting aneurysms with bleeding based on the literature cited, and the trapping of aneurysms may take priority over other methods.

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We report the case of a patient with a medial medullary infarction (MMI) associated with an occlusion of the vertebral artery and basilar artery. A 64-year-old man was admitted to our hospital because he complained of sudden muscle weakness on his right side and dysarthria while walking. Brain computed tomography (CT) showed no hemorrhagic lesions. Diffusion MR imaging showed a slight high-intensity lesion in the left medial medulla. He was given ozagrel and edaravone. After 6 days, diffusion MR imaging revealed a remarkably high-intensity lesion in the left medial medulla. After 7 days, cerebral angiography showed occlusion of the left distal vertebral artery (VA) and basilar artery, and this was diagnosed as an MMI because of an occlusion of the left distal VA. After 14 days, basi-parallel anatomical scanning MR imaging (BPAS-MRI) showed a stenosis of the left distal VA. These data suggested that the VA occlusion was caused by the stenosis with atherosclerosis. His neurological symptoms gradually improved. Distal VA atherosclerosis is an important vascular pathology, mostly giving rise to MMI by way of atherosclerosis branch occlusion. Our experience suggests that BPAS-MRI is an effective method to determine the mechanisms of MMI.

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We describe a case of 58-year-old man who presented with a right internal carotid artery-anterior choroidal artery aneurysm. The patient hoped for the operation of clipping the unruptured aneurysm. His profound ischemia due to temporary occlusion of the anterior choroidal artery was clearly detected during surgery for the internal carotid artery-anterior choroidal artery aneurysm using motor-evoked potential (MEP). Reopening the anterior choroidal artery immediately recovered the MEP amplitude. Because the MEP would have disappeared due to clipping, only wrapping and coating was performed. The normal wrapping and coating material, Bemsheet^®, was used. Therefore, the postoperative course was good, and he left the hospital one week after the operation. However, about two months after the operation, he complained of a fever and staggering. A cerebral infarction in the anterior choroidal artery area was detected using MR imaging, and a right internal carotid artery stricture was detected using MRA. After he was hospitalized, the edema around the right basal ganglia infarction increased, and he developed left hemiparesis, sensory neglect, and disorientation. Vasculitis due to the Bemsheet^® was suspected. A steroid was administered. The fever was alleviated one week after the administration of the steroid, and the inflammation was improved. However, he did not recover from the left hemiparesis, and was transferred to a rehabilitation hospital. This case suggests that Bemsheet^® used when operating can cause an arterial occlusive lesion that is observed following aneurysm surgery, and a safer wrapping and coating material is necessary in the future.

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