Basics
Description
- Developmental venous anomalies (DVAs) are the most common vascular malformation of the brain, representing 60% of all central nervous system vascular malformations. Also known as venous angiomas, DVAs are made up of a cluster of venous radicles that drain into a collecting vein. They occur in 2.5 " 3% of the general population.
- DVAs are associated with cavernous malformations (see below) in 8 " 40% of cases, and 20% of patients with mucocutaneous venous malformations of the head and neck have DVAs. They are also associated with sinus pericranii, a communication between intracranial and extracranial venous drainage pathways in which blood may circulate bidirectionally.
- Cavernous malformations (CMs), also known as cavernous hemangiomas or cavernomas, are multilobulated, low-pressure, and slow-flow vascular structures filled with blood, thrombus, or both. They do not contain elastin or smooth muscle. There is no intervening brain tissue except at the periphery of the lesion.
- Arteriovenous malformations (AVMs) are abnormal clusters of vessels that connect arteries and veins without a true capillary bed and have intervening gliotic brain tissue.
- Vein of Galen malformations (VOGMs) are a specific type of congenital AVM that involves the vein of Galen, which flows into the straight sinus after draining the internal cerebral veins and basal veins.
- Sturge-Weber syndrome (SWS), also known as encephalotrigeminal angiomatosis, is characterized by leptomeningeal angiomatosis, facial port-wine stain (capillary malformation), and glaucoma. Some patients have all 3 findings, although others have just 1 or 2 features.
Pathophysiology
- DVAs are an extreme variation of normal venous development. Typically, venous drainage in the brain occurs through a superficial system and a deep system. DVAs result when a deep venous territory drains toward the surface or when a superficial territory drains to the deep venous system instead of draining in the expected direction. Intervening brain tissue is normal. The mechanism responsible for DVA formation is unknown.
- The pathogenesis of CMs is unknown, although the report of cases of new cavernoma development adjacent to a DVA suggests that DVAs may lead to CM formation. Most CMs occur sporadically, although familial syndromes exist. Several genes have been associated with familial CMs.
- The cause of AVM formation is unknown. A failure of normal capillary development with dysplastic vessels forming between primordial arteriovenous connections has been suggested.
- VOGMs are embryonic AVMs consisting of choroidal arteries draining into the precursor of the vein of Galen. They develop between weeks 6 and 11 of fetal life.
- SWS occurs sporadically in 1/40,000 " 50,000 births and is associated with a somatic mosaic mutation in guanine nucleotide " binding protein G(q) subunit alpha. The pathophysiology is thought to be venous dysplasia, in which the primordial venous plexus that is normally present at 5 " 8 weeks of gestation fails to regress. The location of this plexus around the cephalic end of the neural tube and under the ectoderm destined to form the facial skin accounts for the clinical features. Venous stasis occurs due to the absence of normal cortical venous structures, and hypoperfusion of brain tissue occurs. These findings are unilateral in the majority but can be bilateral in up to 20% of cases.
Diagnosis
History
- DVAs are usually benign and asymptomatic, coming to clinical attention as an incidental finding on a neuroimaging study.
- Headache, seizure, and intracerebral hemorrhage are common in patients with CMs and AVMs. Focal neurologic deficits may result from intracerebral hemorrhage or compression of underlying brain structures by the vascular malformation.
- 95% of newborns with VOGMs present with CHF. Others present with hydrocephalus, subarachnoid hemorrhage, intraventricular hemorrhage, or failure to thrive.
- Infants and older children usually present with hydrocephalus, headache, seizures, exercise-induced syncope, or subarachnoid hemorrhage.
- Facial port-wine stain, seizures, and glaucoma are common in SWS. Other neurologic symptoms include hemiparesis, developmental delay, mental retardation, and strokelike episodes presenting with hemiparesis and visual field defects.
Physical Exam
- Physical exam is normal in children with DVAs and children with CMs or AVMs that have not ruptured. Focal neurologic deficits may persist following intracerebral hemorrhage associated with CMs or AVMs.
- In newborns with VOGMs, signs of congestive heart failure such as tachycardia, respiratory distress, and hepatomegaly may occur. A continuous cranial bruit heard may be heard over the posterior skull, and bounding carotid pulses and peripheral pulses may be present. Scalp veins may be dilated.
- Older infants and children with VOGMs also may present with CHF but more often demonstrate increased head circumference, focal neurologic signs, and failure to thrive. Proptosis may be noted.
- Children with SWS often have a facial port-wine stain, most often in the V1 distribution. Glaucoma is also common. Hemiparesis or seizures may develop.
Diagnostic Tests & Interpretation
Routine blood studies are usually normal. Chest x-ray studies and electrocardiogram may reveal typical changes of high-output CHF in patients with VOGMs.
Imaging
- Neuroimaging studies are required for definitive diagnosis.
- DVAs can be visualized on contrast-enhanced CT or MRI. Diagnosis is made by visualization of the typical "caput medusa " appearance of the radially arranged veins draining into a collecting vein, seen as a linear or curvilinear focus of enhancement. They can also be visualized with conventional angiography, although this is not required unless a patient presents with an acute hemorrhage.
- MRI is better than CT at demonstrating CMs, which have a mulberry appearance. On MRI, they are well-circumscribed lesions of mixed signal intensity on T1- and T2-weighted sequences. Contrast enhancement is variable. They are best seen on gradient-echo T2-weighted images or susceptibility-weighted images, which are sensitive to hemosiderin or deoxyhemoglobin.
- AVMs can be seen with CT/CTA, MR/MRA, and conventional angiography. Dynamic sequences are required to characterize the anatomy of feeding and draining vessels. Conventional angiography is the gold standard.
- VOGMs can be diagnosed on fetal ultrasound or MRI. In newborns, cranial ultrasound shows a large, hypoechoic structure in the region of the vein of Galen. CT shows a high-density mass that enhances with contrast. MRI shows an area of decreased signal intensity or signal void because of high flow within the malformation. CT and MRI also show areas of cerebral ischemia or hemorrhage. Conventional angiography is required before intervention.
- In SWS, CT may show calcifications or atrophy. Gadolinium-enhanced MRI is the most sensitive study, showing leptomeningeal enhancement due to pial angiomatosis. Initial CT and MRI are often normal in the newborn period, so follow-up imaging is required.
Differential Diagnosis
- The differential diagnosis for headaches and seizures, common presenting symptoms of brain vascular malformations, is broad. CNS infection, vascular malformation, hydrocephalus, and mass lesion can result in both. Other causes of seizure include dysplasia and remote brain injury, both genetic and idiopathic. Other causes of headache include benign conditions such as migraine and tension headaches and structural abnormalities such as Chiari I malformations.
- VOGMs must be considered in any newborn with unexplained CHF (especially high-output failure), hydrocephalus, or intracranial hemorrhage. Other causes of high-output CHF in the newborn include anemia, hyperthyroidism, and other AVMs.
- Intracranial hemorrhage may result from AVMs, CMs, aneurysms, bleeding diatheses, hypertension, or trauma in neonates and children. In older children, sickle cell disease, vasculopathies including moyamoya syndrome and vasculitis also can lead to hemorrhage.
Treatment
General Measures
- DVAs do not typically require treatment.
- Anticonvulsants should be used to treat seizures.
- Surgical resection is the only treatment option for CMs, although conservative management may be indicated if the risk of surgery outweighs the potential benefit.
- Treatment options for AVMs include resection via microsurgery, embolization, stereotactic radiosurgery, and conservative management. Risk of hemorrhage ranges 0.9 " 34% per year, so decisions about treatment should be guided by symptoms at presentation and structural features of the AVM.
- Treatment of choice for VOGMs in all ages is endovascular embolization. Direct surgical intervention has unacceptable risks and is no longer recommended. Radiosurgery has been used in a small number of clinically stable older patients. Refractory CHF prompts intervention in neonates. Treatment in older infants and children is indicated to prevent cerebral ischemia (from arterial steal or from venous infarction) and to prevent hydrocephalus. Embolization can be completed in stages over a few months after CHF is controlled.
- Ventriculoperitoneal shunts may be required in patients who develop hydrocephalus following intracerebral hemorrhage related to CM or AVM or in patients with VOGMs.
- Treatment in SWS is targeted to symptoms, using anticonvulsants for seizures and eye drops or ocular shunts for glaucoma. Low-dose aspirin is recommended at the time of diagnosis to prevent further brain injury due to impaired cerebral blood flow. Seizures can lead to ongoing brain injury by increasing metabolic demand in brain tissue that has abnormal perfusion at baseline, so aggressive seizure management is recommended. Some children with intractable epilepsy may be good candidates for epilepsy surgery.
Ongoing Care
- Generally, no specific follow-up is required for patients with DVAs.
- Follow-up with a neurologist is indicated for patients with CMs, AVMs, VOGMs, and SWS.
- Neurosurgical consultation is indicated for patients with CMs, AVMs, and VOGMs.
- A follow-up CT or MRI is indicated to evaluate patients with new neurologic signs or symptoms.
- Ophthalmologic follow-up is indicated for patients with SWS and most patients with VOGMs, especially prior to treatment when hydrocephalus may develop.
Prognosis
- Prognosis is excellent for patients with isolated DVAs.
- Prognosis for patients with CMs and AVMs depends on the size, location, presenting symptoms, and specific characteristics of the lesion. Patients who have experienced an intracerebral hemorrhage have worse prognosis than those who have not.
- For patients with VOGMs, earlier age of symptoms is associated with worse prognosis. Mortality in neonates with symptomatic lesions is 36%. In a recent meta-analysis of 337 patients treated with endovascular embolization between 2001 and 2010, 84% had a good or fair clinical outcome, and mortality was 16%.
- Prognosis in patients with SWS depends on the extent and location of involvement. Seizures occur in the majority ( ’ Ό85%), with low normal intelligence or mental retardation in ’ Ό35%.
Complications
- Death can occur in patients with intracerebral hemorrhage due to CMs or AVMs.
- Mortality approaches 100% in untreated patients with VOGMs.
- In severe case of VOGMs, 80% of cardiac output may be delivered to the head because of the low vascular resistance within the malformation. Cardiac ischemia may occur because of decreased coronary artery blood flow.
- Intracerebral hemorrhage may occur as a result of CMs, AVMs, and VOGMs or as a complication of treatment.
- Longer term complications from CMs, AVMs, and VOGMs include mental retardation, seizures, hydrocephalus, and chronic motor impairment.
- In patients with SWS, visual impairment can result if glaucoma is difficult to control. Persistent hemiparesis can develop.
Patient Monitoring
- Serial neuroimaging should be performed in patients with CMs, AVMs, and VOGMs to guide the timing of treatment and to assess for recurrence.
- Head circumference should be monitored in patients with VOGMs as a marker of hydrocephalus.
Additional Reading
- Geibprasert S, Pongpech S, Jiarakongmun P, et al. Radiologic assessment of brain arteriovenous malformations: what clinicians need to know. Radiographics. 2010;30(2):483 " 501. [View Abstract]
- Khullar D, Andeejani AMI, Bulsara KR. Evolution of treatment options for vein of Galen malformations: a review. J Neurosurg Pediatr. 2010;6(5):444 " 451. [View Abstract]
- Niazi TN, Klimo P Jr, Anderson RC, et al. Diagnosis and management of arteriovenous malformations in children. Neurosurg Clin N Am. 2010;21(3):443 " 456. [View Abstract]
- Puttgen KB, Lin DDM. Neurocutaneous vascular syndromes. Childs Nerv Syst. 2010;26(10):1407 " 1415. [View Abstract]
- Rammos SK, Maina R, Lanzino G. Developmental venous anomalies: current concepts and implications for management. Neurosurgery. 2009;65(1):20 " 30. [View Abstract]
- Ruiz DSM, Yilmaz H, Gailloud P. Cerebral developmental venous anomalies: current concepts. Ann Neurol. 2009;66(3):271 " 283. [View Abstract]
Codes
ICD09
- 747.81 Anomalies of cerebrovascular system
- 759.6 Other hamartoses, not elsewhere classified
- 228.02 Hemangioma of intracranial structures
ICD10
- Q28.3 Other malformations of cerebral vessels
- Q85.8 Other phakomatoses, not elsewhere classified
- D18.02 Hemangioma of intracranial structures
SNOMED
- 65587001 Congenital anomaly of cerebrovascular system (disorder)
- 19886006 Sturge-Weber syndrome (disorder)
- 444869007 Cavernous hemangioma of brain (disorder)
- 234142008 Cerebral arteriovenous malformation (disorder)
FAQ
- Q: Can the AVM recur after treatment?
- A: AVMs have a propensity to recur. Imaging studies give a good indication of the likelihood of recurrence.
- Q: How does a vascular malformation cause seizures?
- A: Seizures can result from ischemia, hemorrhage, or acute hydrocephalus associated with the malformation.