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A 42-year-old man presented with asymptomatic traumatic carotid artery dissection 3 months after sustaining blunt injury with tracheal laceration. Magnetic resonance imaging performed as a screening procedure for asymptomatic carotid artery injury unexpectedly showed dissection of the carotid artery. Angiography confirmed carotid artery dissection with narrowing of the true lumen. Balloon angioplasty and stent placement were carried out to dilate the true lumen and isolate the false lumen from blood flow. Intravascular ultrasonographic virtual histology defined the precise anatomic structure of the lesion and identified the internal flap as fibrotic. Careful clinical assessment of patients with blunt cervical trauma may permit diagnosis of carotid artery dissection and intervention prior to the development of cerebral ischemic symptoms.

A 30-year-old man presented with an aneurysm of the left posterior inferior cerebellar artery manifesting as subarachnoid hemorrhage and cerebellar infarction. Angiography demonstrated string-of-beads sign typical of fibromuscular dysplasia (FMD) in the extracranial carotid and vertebral arteries. The aneurysm and the parent artery were successfully embolized with Guglielmi detachable coils. Severe vasospasm developed 1 week after admission, and was treated several times by selective injection of vasodilator. A new aneurysm of the left external carotid artery became evident 1 month later, whereas only slight dilation had previously been apparent. This angiographic sequence demonstrated a new arterial dissection. Despite the possibility of damage to the artery during multiple catheterizations, arterial wall changes caused by FMD appear to have been primarily responsible. This case emphasizes the need for particular care in performing vascular interventional procedures in the presence of FMD.

A 35-year-old man developed osteosarcoma of the left parietal and occipital bones 16 years after radiotherapy for glioma in the right occipital lobe. Radiotherapy of the primary neoplasm used 50 Gy administered to a localized field through two lateral ports. The secondary neoplasm arose contralateral to the primary lesion but within the irradiated field. The tumor had a multilocular cyst with considerable intracranial extension, and symptoms of elevated intracranial pressure were prominent early in the course. After a short-lived initial remission following surgical intervention and chemotherapy, the patient deteriorated because of tumor recurrence and died 18 months after the diagnosis. Radiation-induced osteosarcoma is a well-known but rare complication of radiotherapy for brain neoplasms with a poor prognosis.

A 19-year-old male presented with sudden onset of right hemiparesis caused by left cerebral hemorrhage. Cerebral angiography demonstrated no vascular abnormality, and the hematoma was removed surgically. At operation, no abnormal vascular lesion was found in the brain adjoining the hematoma. Two years later, magnetic resonance (MR) imaging demonstrated a few foci of flow voids adjacent to the hematoma cavity. Four years after the hemorrhage, MR imaging showed more extensive flow-void abnormalities that indicated growth of an occult arteriovenous malformation (AVM). Cerebral angiography indicated a definite AVM supplied mainly by branches of the middle cerebral artery. Total resection of this lesion was performed. The histological diagnosis was typical AVM. Immunohistochemistry with vascular endothelial growth factor showed staining in the walls of the abnormal vessels. Serial MR imaging is very useful for the diagnosis and management of occult AVMs.

Two cases of embolic stroke associated with vascular anomalies were treated by intraarterial fibrinolytic therapy. A 78-year-old male had embolic stroke associated with fenestration of the middle cerebral artery (MCA). The embolus lodged in the terminal portion of the right internal carotid artery (ICA) and in the M2 portion of the right MCA. The fenestration was not detected before local fibrinolytic therapy, but was identified by postinterventional angiography. An 82-year-old female had a left-sided persistent primitive trigeminal artery (PPTA), and the embolus lodged in the terminal portion of the left ICA. Left internal carotid angiography also showed rich collateral circulation via the abundant leptomeningeal anastomosis. The PPTA involved the left ICA, so the anomalous anatomy had to be considered in performing local thrombolysis. However, the rich collateral circulation allowed recanalization of the occluded ICA without inducing bleeding. Dissolution of persistently adherent emboli must be performed with great care because of the possibility of such rare vascular anomalies.

A 39-year-old male presented with an exceedingly rare primary intracranial epithelioid angiosarcoma in the right parietal lobe manifesting as weakness of the left hand. Neuroimaging revealed a well-defined intensely enhanced lesion in the right parietal lobe with peripheral cerebral edema. The tumor was grossly totally removed. Light microscopy of the surgical specimens revealed features typical of an epithelioid vascular tumor. The tumor cells showed intense positive immunohistochemical staining for cytokeratin and vimentin and focally positive staining for both Ulex europaeus agglutinin and anti-human endothelial cells, CD31. Tumor regrowth required two further operations. This progressive growth was consistent with an angiosarcoma. The tumor was diagnosed as an epithelioid angiosarcoma based on the histological and clinical characteristics. He became progressively obtunded and finally died. This is the first intracranial epithelioid angiosarcoma which expressed epithelial markers detectable by immunohistochemical methods.

A 39-year-old male experienced unilateral right hearing loss and tinnitus for 7 years and was hospitalized after he suddenly developed severe headache, vertigo, and right facial paralysis. Computed tomography (CT) showed a round, high-density are in the right cerebellopontine angle. Magnetic resonance (MR) imaging demonstrated a crescent-shaped region of high signal intensity, representing hemorrhage, in the superior aspect of the tumor, surrounded by edema. The right internal auditory canal was enlarged. Four-vessel angiography disclosed neither an aneurysm nor an arteriovenous malformation. A right suboccipital craniectomy revealed an encapsulated mass 3 cm in diameter in the right cerebellopontine angle. The tumor was totally removed. Histological examination revealed a typical neurinoma composed of Antoni type A and B cells. After undergoing anastomosis of the right hypoglossal and facial nerves, the patient was discharged in good condition. In this case MR imaging demonstrated intratumoral hemorrhage (which is rare in cases of acoustic neurinoma) and the surrounding tissue more clearly than did CT scanning.