Cerebral vascular malformations: applications of magnetic resonance imaging to differential diagnosis

Cavernous malformations

Cavernous malformations (CMs) are vascular lesions found in the central nervous system (CNS) and throughout the body and have been called cavernomas, cavernous angiomas, and cavernous hemangiomas. This article discusses the epidemiology, natural history, diagnosis, treatment and follow-up of children who are found to harbor these lesions. CMs affect children by causing hemorrhage, seizure, focal neurologic deficits, and headache. Diagnosis is best made with magnetic resonance imaging. Patients with multiple lesions should be referred for genetic evaluation and counseling. Individuals with symptomatic, growing, or hemorrhagic malformations should be considered for surgical resection. Close follow-up after diagnosis and treatment is helpful to identify lesion progression or recurrence.

Delayed radiation necrosis with extensive brain edema after gamma knife radiosurgery for multiple cerebral cavernous malformations--case report

A 39-year-old man presented with multiple intracranial cavernous malformations manifesting as intractable seizures persisting for more than 20 years. He underwent gamma knife radiosurgery (GKRS) for right frontal and left temporal cavernous malformations. He began to suffer from progressive left hemiparesis and inattention 2 years 5 months after the GKRS. Magnetic resonance imaging showed abnormal ring enhancement and extensive brain edema around the right frontal lesion. Conservative therapies such as external decompression, low-dose barbiturates, and mild hypothermia had no effect on his clinical status. Stereotactic biopsy of the ring-enhanced area demonstrated gliosis. Signs of cerebral herniation appeared, so we performed partial resection of the right frontal lobe. His symptoms recovered immediately. Subsequent hyperbaric oxygen (HBO) therapy significantly improved the extensive brain edema. Delayed radiation necrosis associated with potentially fatal brain edema may occur after GKRS for cavernous malformations. Internal decompression and subsequent HBO therapy were very effective for the treatment of these lesions.

Cerebral venous thrombosis and venous malformations in children

Venous strokes are not as common as arterial strokes in the pediatric population, but may be associated with significant mortality and morbidity. Cerebral vein thrombosis and venous sinus thrombosis are responsible for most venous strokes. Vein of Galen malformation is a rare but important cause of mortality in neonates and infants. Awareness of these potential causes of stroke in the pediatric population, early diagnosis, and appropriate therapeutic strategies are paramount to reduce mortality and improve neurologic outcome.

Congenital multiple cavernous angiomas associated with thrombosed arteriovenous malformation of the brain--case report

A 16-year-old girl presented with multiple cerebral cavernous angiomas with calcifications due to repeated hemorrhages and a thrombosed cerebral arteriovenous malformation (AVM). Her 18-year-old elder sister also had multiple cerebral cavernous angiomas associated with calcifications, which suggested presence of repeated previous hemorrhages. Surgical removal via a right occipital craniotomy resulted in a good outcome. The histological diagnosis was thrombosed AVM. Evaluation of congenital vascular anomaly needs to take into consideration the combination of other congenital vascular anomalies and their familial occurrence.

Reoperation for recurrent temporal lobe epilepsy

The indications for the risks and outcome of reoperation for medically refractory temporal lobe epilepsy have not been well documented. A retrospective review is presented of 40 patients who underwent reoperation on the temporal lobe for recurrent seizures. The mean patient age at the first operation was 22 +/- 7 years (+/- standard deviation). Electrocorticography during the first operation showed interictal epileptic abnormalities from surface electrodes in 97% of the cases and from depth electrodes in the mesiotemporal structures in 38%. The seizures recurred with the same pattern within 6 months after the first operation in 60% of patients and within 2 years in 90%. Postoperative neuroimaging studies showed residual mesiotemporal structures in all cases. The mean time between the two operations was 5.5 +/- 5 years and the mean patient age at the second operation was 28 +/- 8 years. The second operation involved focal resection of the mesiotemporal structures in 30 cases. The mean postoperative follow-up period was 4.8 +/- 2.7 years (range 2 to 11 years). After the second operation, 63% of the patients were seizure-free or had rare seizures (one or two per year). There were no permanent neurological complications. Patients who did not benefit from reoperation had electroencephalographic abnormalities in multiple brain areas. Reoperation for temporal lobe epilepsy effectively controls seizures in the majority of patients, and the procedure is safe if rigorous technical rules are observed. More complete resection of mesiotemporal structures during the first operation, even in the absence of intraoperative electrographic abnormalities, could prevent the need for reoperation in defined cases.

Pathological heterogeneity of angiographically occult vascular malformations of the brain

There is considerable confusion in the literature regarding the pathological substrates of angiographically occult vascular malformations (AOVMs) of the brain and their clinical significance. We retrospectively reviewed the cases of 34 consecutive patients with AOVMs undergoing surgical excision at a single institution during a 10-year period. Pathological specimens were reexamined, and the lesions were classified according to strict histopathological criteria. There were 21 cavernous malformations, 3 arteriovenous malformations, 3 venous malformations, 2 capillary malformations, and 5 mixed (pathologically heterogeneous) lesions. The initial pathological diagnostic report had been imprecise or had misidentified the lesion type in 18 of the 34 cases (53%), most commonly labeling a cavernous malformation as an arteriovenous malformation or not recognizing mixed features within the same lesion. Clinical presentation (including hemorrhage) and outcome were not significantly different among the various lesion types. Preoperative diagnostic imaging included a variety of modalities that were introduced or evolved during the period of the study and generally suggested a suspected vascular malformation but did not predict pathological subtypes. Acute hematomas in this surgical series made the identification of underlying vascular malformations highly speculative. We conclude that the majority of AOVMs requiring surgical intervention are cavernous malformations, although there was a notable pathological heterogeneity of the remaining lesions. Histopathological subtypes of AOVMs are not associated with unique clinical or radiographic features.

Cerebral venous angiomas: surgery as a mode of treatment for selected cases

Eleven patients with venous angiomas, 6 males and 5 females ranging in age from 4 to 58, are presented. Four patients presented with intracerebral haematoma and 3 patients had associated cavernous angioma, respectively. Patients with intracerebral haematoma had signs and symptoms due to the localization of the haematoma. The other patients presented with headache, seizures, vertigo, ataxia and mental disturbances. Pre-operative diagnosis was based on computerized tomography, magnetic resonance imaging and cerebral angiography. In 9 surgical cases it was confirmed by histopathological examination of operative specimens. After establishing the type, size and location of the lesion decision for operative treatment was made in nine cases, in four of them because of the presence of an intracerebral haematoma and in 5 of them due to severe disability. Eight of these 9 patients recovered completely and one improved. No severe cerebral oedema was encountered after converging medullary veins were excised and main draining veins partially coagulated. In this small series we encountered an unexpectedly large percentage of venous angiomas causing intracerebral haemorrhage which are commonly considered more benign than other vascular malformations. After reviewing previously reported cases of venous angiomas causing intracerebral haemorrhage and severe neurological deficit we think that the term "benign" is worth reconsidering. We propose a thorough examination of each case of venous angioma and the operative treatment when appropriate taking into account patients state and location of angioma.

Cervical intramedullary cavernous angioma with MRI-proven haemorrhages

Two contrasting cases of cervical intramedullary cavernous angioma in young female patients are reported. One patient had a 3-year course of step-wise progressive tetraparesis; at each of the five events intramedullary bleeding from a cryptic vascular malformation at C6-7 level was diagnosed by MRI. The other patient presented with one episode which led to MRI diagnosis of a vascular malformation at the C2 level. Both patients eventually underwent complete surgical excision of the angioma with subsequent steady improvement of the neurological deficit.

The natural history of intracranial venous angiomas

Cerebral venous angiomas are congenital anomalies of the intracranial venous drainage. Many believe that they are associated with a high risk of hemorrhage and neurological dysfunction, but newer neurodiagnostic imaging techniques are showing not only that they are more common than previously known but also that many have no associated symptoms. In this retrospective study, the natural history of venous angiomas was examined in 100 patients (48 males and 52 females) with radiographically identifiable lesions treated over a 14-year period. Information on the natural history of the lesion was obtained from clinical records and follow-up data. Imaging studies included angiography, computerized tomography, and magnetic resonance imaging. Angioma locations were classified as frontal (42 cases), parietal (24 cases), occipital (4 cases), temporal (2 cases), basal or ventricular (11 cases), cerebellar (14 cases), or brain stem (3 cases); 47 lesions were on the left side. Headache as a presenting symptom was common (36 patients) and often led to other radiographic studies, but this appeared to be related to the vascular lesion in only four patients. Other possibly related complications were hemorrhage in one patient, seizures in five, and transient focal deficits in eight. Fifteen patients had no neurological signs or symptoms. The mean patient age at last contact was 45.3 years (range 3 to 94 years). All patients have been managed without surgery. It is concluded that significant complications secondary to venous angiomas are infrequent and that surgical resection of these lesions and of surrounding brain is rarely indicated.

The case for conservative management of venous angiomas

Venous angiomas (developmental venous anomalies) are vascular malformations increasingly recognized in general neurosurgical or neurological practice. They are associated with intracranial hemorrhage, seizures, or progressive neurological deficits or found as incidental findings in patients who present with headaches or have neuroimaging studies for investigation of unrelated neurological disorders. Since venous angiomas drain normal cerebral tissue within a functionally normal arterial territory, resection can lead to venous infarction. This report studies 27 patients with venous angiomas, all of whom had conservative treatment. The venous angioma was considered to be responsible for the onset of neurological symptoms in 14 patients (7 with hemorrhage, 3 with hemorrhage and seizures, 2 with seizures, one with an extrapyramidal movement disorder, and one with motor deficit). Thirteen patients had incidental lesions (8 with headache, and 5 with unrelated neurological symptoms). Ten venous angiomas were in the posterior fossa; seven in the cerebellum. Location did not correlate with symptomatic presentation. No patient with hemorrhage required surgical evacuation of the hematoma. No patient died or had significant morbidity during the follow-up interval (mean of 3.7 years). Venous angiomas are low flow, low resistance vascular malformations, many of which are not associated with neurological sequelae. Our series supports the concept that surgical removal or radiosurgical obliteration should not be performed unless a patient has a second life threatening hemorrhage.

Third ventricle cavernous angioma: report of two cases

Cavernous angioma arising in the third ventricle is an extremely rare disease. We have reviewed five cases previously reported, as well as our own two cases, and discuss the clinical characteristics of and surgical approach to cavernous angioma at this site. The bifrontal craniotomy and interhemispheric translamina terminalis approach minimize the damage to the brain and allow for an approach to the third ventricle in a wide operative field with minimal compression of the brain itself. We have found this approach to be suitable for surgery on angiomas of the anterior half of the third ventricle.

Magnetic resonance imaging of intracranial venous angiomas

Magnetic resonance imagings (MRI) were made of intracranial venous angioma (six angiographically proved, four presumed). All draining veins were identified as a linear or a small round structure with a flow void. The stellate configuration was observed in seven of the ten patients. In two of the ten, the associated intraparenchymal hematoma was evident. Increased intensity of adjacent parenchyma on T2-weighted images was detected in four of ten patients, and a decreased intensity on the T1-weighted images was noted in three of eight. Thus, MRI is a pertinent diagnostic modality for evaluating intracranial venous angioma. Angiography does not seem to be required for confirmation in patients with typical MR findings.