Purpose: The long-term outcomes after Gamma Knife surgery (GKS) were retrospectively analyzed in patients with posterior fossa arteriovenous malformations (AVMs) to evaluate the efficacy, safety, and indications for this procedure.Methods: The medical records were reviewed of 75 patients who underwent GKS between 1992 and 2005 in our institution. Results: The rate of complete AVM obliteration was 57.3% at 3 years and 80.2% at 5 years after GKS. Multivariate analysis showed that the significant factors for higher obliteration rates were younger patient age, smaller nidus volume, and smaller nidus maximum/minimum diameter. Two patients suffered hemorrhages during the latency interval. Clinical deterioration was observed in 10 patients with radiation-induced edema after the GKS. Larger nidus volume and AVM located adjacent to eloquent areas were significantly associated with the risk of neuropathy after GKS. One patient developed radiation-induced necrosis 4 years after confirmation of complete AVM obliteration. Conclusions: GKS is an effective and safe modality for the treatment of posterior fossa AVMs, resulting in high AVM obliteration rate with low complication rates based on neuroimaging and neurological symptoms. Posterior fossa AVMs tend to occur adjacent to eloquent areas, so we recommend preparing a conformed dose plan that considers both obliteration of the AVM nidus and preservation of neurological function.

View full abstract

[Background and aims] Readmission after hospitalization for ischemic stroke is a burden to patients and their families physically, mentally, and economically. Our aim was to find causes, characteristics, and issues of readmission. [Methods] From January 2005 to September 2009, among 1193 consecutive patients hospitalized for ischemic stroke, we studied 1136 patients (57 had died on first admission). [Results] Within 90 days after discharge, 125 patients (11.0%) were readmitted. Forty-seven patients (4.1%) were readmitted for vascular and bleeding event, 31 patients (2.7%) for recurrent ischemic stroke, and 5 patients (0.44%) for intracranial hemorrhage. Sixty patients (5.3%) had unscheduled readmissions due to infections, fractures, malignant tumors, and so on. Eighteen patients (1.6%) had scheduled readmissions. [Conclusions] The leading cause for readmission after hospitalization for ischemic stroke was recurrent stroke. We should focus on secondary prevention immediately after discharge throughout the region.

View full abstract

A 17-year-old woman was admitted to our hospital with acute right hemiplegia. At first examination, the patient showed moderate dysarthria and hemiplegia. MR diffusion-weighted imaging showed high intensity at the left basal ganglia, and MRA showed occlusion of left middle cerebral artery at the M1 position. We administered alteplase intravenously within 3 hours after the onset. The patient's NIHSS improved from 12 to 0 within 120 minutes after administration. An artrial septal defect (ASD) was detected using transesophageal echocardiography, and she underwent ASD closure via a thoractomy one month after the onset. She recovered to have mild weakness of the right limbs and returned back to her school life. Although there is no consensus concerning intravenous rt-PA therapy for juvenile ischemic strokes, rapid MR examination should be performed to rule out brain infarction when a juvenile patient without a previous medical history shows a rapid onset of hemiplegia, and we should take it as an indication for thrombolytic therapy.

View full abstract

A 39-year-old woman with migraines without auras since adolescence presented with a sudden and severe left-sided headache with homonymous visual field impairment. 1.5T-MRI revealed an acute cerebral infarction in the left posterior cerebral artery (PCA) territories. Cerebral MRA and conventional angiography showed a dilated left PCA at the P2 segment but failed to delineate the intimal flap. However, 3T-MRA revealed an intimal flap clearly separating the lumen at the dilated P2 segment of the left PCA, and thus, dissection was confirmed. 3T-MRI seems superior to the more widely used 1.5T scanner and catheter arteriography for detecting the intimal flap of relatively small artery dissections. Cerebral artery dissection goes through dynamic morphologic changes, and thus, serial vascular imaging is necessary for evaluation. 3T-MRI is suitable for such high-resolution imaging in a non-invasive manner.

View full abstract

We report a case of anterior inferior cerebellar artery (AICA) syndrome due to vertebral artery dissection following a minimal neck injury. The patient was a 16-year-old male who developed a throbbing headache in the left occipital area during sumo sparring. He endured the headache and continued to practice sumo on successive days. Three days later, he developed vertigo, right hearing loss, and right tinnitus soon after impacting an opponent during sparring. The patient was admitted to our hospital with suspicion of sudden deafness. The following morning, he developed right peripheral facial paralysis, hypothermoesthesia and hypoalgesia of the right face, and cerebellar ataxia of the right upper limb and trunk. Diffusion-weighted MRI showed high signal intensity in the territory of the right AICA and the right posterior inferior cerebellar artery (PICA). MRA showed left vertebral artery occlusion, basilar artery stenosis, and right AICA occlusion. An anticoagulant and edaravone were immediately administered. Twenty days later, cerebral angiography showed recanalization of the right AICA. Some symptoms gradually improved, but right hearing loss and truncal ataxia remained. This case suggests artery-to-artery embolism from vertebral artery dissection as a possible mechanism of AICA syndrome.

View full abstract

Ruptured lateral posterior choroidal artery (LPChA) aneurysms are a quite rare pathogenesis of intraventricular hemorrhage (IVH). To our knowledge, most reported cases were associated with moyamoya disease. Our patient, however, showed neither moyamoya disease nor another anterior circulation occlusive disease. This 60-year-old man had sudden consciousness disturbance and was referred to our department. A CT scan revealed an IVH in the bilateral lateral ventricles and fourth ventricle. To investigate the bleeding origin, three-dimensional CT angiography was performed. However, no definite vascular lesion was found. On the admission day, evacuation of the IVH was done using an endoscope. In the subacute stage (17th day after onset), cerebral angiography revealed a right LPChA aneurysm without moyamoya disease. On the 26th day, under a navigation system, this aneurysm was trapped and excised using a transcortical (inferior temporal gyrus) and transventricular approach. In most reported cases, LPChA aneurysms were considered to be pseudoaneurysms secondary to the rupture of fragile collateral vessels of moyamoya disease. However, this case did not have associated moyamoya disease. In this case, we hypothesized the pathogenesis as follows. First, the usual microaneurysm that causes hypertensive intracerebral hemorrhage was generated on the LPChA without surrounding tissue compression. Under this condition, the microaneurysm was enlarged and finally collapsed in the lateral ventricle as a pseudoaneurysm without moyamoya disease.

View full abstract

We here report on a patient with neurological and neuroimaging findings of spontaneous cerebrospinal fluid hypovolemia (SCH) who developed cerebral venous thrombosis (CVT) and a subdural hematoma (SDH). A 31-year old man, without underlying previous illness, major trauma, or lumbar puncture, was admitted to our hospital presenting with an orthostatic headache following transient diplopia, right blepharoptosis, nausea, muzziness, and right hemiparesis. He was diagnosed with SCH complicated by CVT on the basis of neurological and neuroimaging findings. His SCH and CVT improved with rest, maintenance infusion, heparin, and an oral anticoagulant; however, he soon had the complication of a bilateral SDH. A cerebrospinal fluid examination revealed increased intracranial pressure, so he was followed closely without an epidural blood patch, resulting in spontaneous healing of the SDH. Compensatory reactions for leakage of cerebrospinal fluid in SCH cause secondary CVT and SDHs. Therefore, we need to assess the underlying pathogenic mechanisms of SCH in choosing treatments for the secondary CVT and SDHs.

View full abstract

We here report a case of a recurrent bilateral anterior cerebral artery dissection five years after the initial dissection. A 38-year-old man developed headache associated with right hemiparesis. MRI revealed a brain infarction in the left frontal lobe, and the A2 portion of anterior cerebral artery occlusion was shown using MR angiography (MRA). Because there was obstruction of the left anterior cerebral artery and detection of an intramural hematoma using MRA, a diagnosis of a left anterior cerebral artery dissection was made. He was discharged without any neurological sequelae. Five years after the left anterior cerebral artery dissection onset, he developed a sudden headache and was again admitted to our hospital. Brain CT showed a hemorrhagic infarction in the right frontal lobe. MRA showed narrowing of the left anterior cerebral artery and occlusion of the right anterior cerebral artery at the proximal part of the callosomarginal artery. T1-weighted and black-blood contrast-enhanced T1-weighted MRI showed an intramural hematoma in the lesion, and we diagnosed a right anterior cerebral artery dissection. Although recurrent contralateral anterior cerebral artery dissection of long-term course after the initial dissection is rare, we should consider recurrence when headache with or without neurologic symptoms is present in patients with past cerebral artery dissections. For cases in which intracranial cerebral artery dissection is suspected, MRA, T1-weighted imaging, and black-blood contrast-enhanced T1-weighted imaging may show the characteristic vascular pathology.

View full abstract

We describe 2 cases with different clinical courses of diffusion-weighted MRI of hypoglycemic encephalopathy with reversible high signal intensity localized in the posterior limb of the internal capsule. In the first patient (a man aged 75 years), the area of abnormal high signal intensity was situated bilaterally; however, he had right-dominant motor weakness before being brought to our hospital and was in a deep coma on arrival. This patient was treated adequately, and the second image taken using diffusion-weighted MRI was normal six days after onset. He left the hospital without neurological deficits within ten days after onset. In the second patient (a woman aged 92 years), the area of abnormal high signal intensity was also situated bilaterally; however, she had left dominant motor weakness and disturbance in consciousness on arrival. The findings in this patient were initially misinterpreted as acute cerebral infarction, so she was not supplemented with adequate glucose until 48 hours after onset. The second image taken using diffusion-weighted MRI revealed a new lesion in the corona radiata. Though the diffusion-weighted MR image returned to normal one week after onset, it took more than one month for her to recover her original activities of daily living. Although cerebral infarction and hyperglycemia exhibit similar findings using diffusion-weighted MRI, it is important to consider the possibility of hypoglycemic encephalopathy because it can be effectively treated and reversed, leading to complete recovery.

View full abstract

We report a case of a patient who underwent a carotid endarterectomy for atheromatous pseudo-occlusion of the right internal carotid artery immediately after thrombolysis due to an intravenous injection of a recombinant tissue-type plasminogen activator (rt-PA, alteplase). A 75-year-old man was admitted to the emergency room of our hospital with unconsciousness and left hemiparesis. A computed tomography scan showed no signs of ischemia. Intravenous rt-PA therapy (348,000 IU/kg) was administered. He did not show significant improvement after administration, and a percutaneous transluminal angioplasty (PTA) was unsuccessfully performed. Immediately, a carotid endarterectomy (CEA) for atheromatous pseudo-occlusion of the right internal carotid artery was successfully performed. We conclude that emergent carotid endarterectomy can be a salvage therapy after rt-PA therapy is unsuccessfully performed.

View full abstract