History and exam
Key diagnostic factors
common
sudden-onset focal neurologic deficit
If progressing over minutes to hours, suggests an intracerebral hemorrhage (ICH). Such progression is uncommon in ischemic stroke and subarachnoid hemorrhage.
In drug users, although uncommon, sudden-onset focal neurologic deficit may occur immediately following drug misuse. In this case, it should alert to possibility of ICH secondary to a vascular lesion.[38]
seizures
Generalized seizures, or simple or complex partial seizures ± secondary generalization.
reduced conscious level
May be secondary to a seizure or reflect the size and mass effect of an intracerebral hemorrhage (ICH). ICH volume and Glasgow Coma Scale score are strong predictors of death within 30 days.[45]
Other diagnostic factors
common
sudden-onset headache
More common with hemorrhagic than with ischemic stroke but not a key diagnostic factor, as with subarachnoid hemorrhage.
In drug users, although uncommon, sudden-onset headache may occur immediately following drug misuse. In this case, it should alert to possibility of intracerebral hemorrhage secondary to a vascular lesion.[38]
nausea
Common with intracerebral hemorrhage.
vomiting
More common with intracerebral hemorrhage than with ischemic stroke or subarachnoid hemorrhage.
confusion
Common with intracerebral hemorrhage.
gradual-onset headaches
There is controversy as to whether unruptured AVMs cause headaches, or if their relationship is coincidental. Reported headaches tend to be unilateral, ipsilateral to the AVM, and atypical in nature.[2]
hypertension
Patients are often hypertensive during and immediately following an intracerebral hemorrhage. This does not necessarily reflect established hypertension and may be an autoregulation response to elevated intracranial pressure.
coma
Common with intracerebral hemorrhage.
uncommon
gradual-onset focal neurologic deficit
Focal neurologic symptoms that are not related to hemorrhagic events tend to be of gradual onset and may be transient, persistent, or progressive.[2] Between 5% and 15% of AVMs present with progressive neurologic deficits unrelated to hemorrhage.[46] The theoretical explanation is the "vascular steal phenomenon", which remains controversial.[54]
cognitive dysfunction
Generally, IQs are similar in patients with AVMs and the normal population.[53] Prevalence of cognitive disturbance among those with AVMs is not known. Any cognitive problems seem to develop after starting school and often cannot be directly attributed to the location of the AVM.
Risk factors
strong
familial (malformation)
Familial AVMs are extremely rare. More common in females and supratentorial, but incidence is not high enough to establish an association with a particular genetic factor instrumental in angiogenesis.[32]
Familial syndromes such as ataxia telangiectasia, Wyburn-Mason syndrome, hereditary hemorrhagic telangiectasia (HHT; also called Rendu-Osler-Weber syndrome), and Sturge-Weber syndrome have been associated with AVMs. Approximately 10% of patients with HHT have AVMs.[33]
previous hemorrhages (risk of hemorrhage)
Overall annual risk of hemorrhage is 2% to 4%. Risk is increased during the first 5 years following hemorrhage, being highest in the first year with reported rates of >30%.[31][34][35] However, hemorrhage risk seems to be overestimated in those without hemorrhagic presentation, where rates of <1% have been shown. In these patients, risks of treatment may outweigh risk of rupture.[22][36]
drug abuse (risk of hemorrhage)
Illicit drug abuse is the most common risk factor for stroke in young adults.[37] This occurs by a variety of pathophysiologic mechanisms, but these patients frequently have underlying vascular lesions, including AVMs. The hypertensive effects of drugs such as amphetamines, cocaine, and ecstasy increase the risk of rupture.[38]
weak
abnormal venous drainage (risk of hemorrhage)
Factors that increase intracranial venous pressure may increase risk of rupture. Deep venous drainage, a single draining vein, venous stenosis, and high feeding arterial pressure have consistently been shown to be associated with AVM hemorrhage in retrospective studies. The association with venous reflux is less consistent.[2]
small AVMs (risk of hemorrhage)
Hospital series of patients with a hemorrhage from AVMs have shown a higher frequency of small, rather than large, AVMs.[4][27][39][40] This may reflect that small AVMs are less likely to present with seizures or neurologic symptoms, or that small AVMs (both symptomatic and asymptomatic) are simply more common. However, they have higher feeding arterial pressures and resistance than larger lesions, and are thought to be at greater risk of rupture.[40] Nevertheless, a long-term follow-up study suggests that large AVM size is an independent risk factor for further hemorrhage.[34]
posterior fossa and deep AVMs (risk of hemorrhage)
coexisting aneurysms (risk of hemorrhage)
pregnancy (risk of hemorrhage)
Evidence is inadequate to determine whether pregnancy influences risk of AVM rupture. Studies of women of childbearing age have reported contradictory findings.[43][44] While there is no evidence that the mode of delivery influences risk of hemorrhage, patients with an untreated AVM would normally be advised to have an elective cesarean section.
hypertension (risk of hemorrhage)
Hypertension is a major risk factor for intracerebral hemorrhage (ICH). It is often considered to be the primary cause, and generally increases the risk of ICH.[45] With underlying AVM, hypertension possibly increases risk of bleeding, by increasing the feeding arterial pressure. However, retrospective studies have shown no clear association.[2]
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