Object. Patients with arteriovenous malformations (AVMs) in a deep location and with deep venous drainage are thought to be at higher risk for hemorrhage than those with AVMs in other locations. Despite this, the natural history of AVMs of the basal ganglia and thalamus has not been well studied.
Methods. The authors retrospectively evaluated a cohort of 96 patients with AVMs in the basal ganglia and thalamus with respect to the tendency of these lesions to hemorrhage between the time of detection and their eventual successful management.
The 96 patients studied had a mean age of 22.7 years at diagnosis, and 51% were male. Intracranial hemorrhage (ICH) was the event leading to clinical detection in 69 patients (71.9%), and 85.5% of these patients were left with hemiparesis. After diagnosis, 25 patients bled a total of 49 times. The cumulative clinical follow up after detection but before surgical management was 500.2 patient-years. The risk of hemorrhage after detection of an AVM of the basal ganglia or thalamus was 9.8% per patient-year.
Conclusions. The rate of ICH in patients with AVMs of the basal ganglia or thalamus (9.8%/year) is much higher than the rate in patients with AVMs in other locations (2–4%/year). The risk of incurring a neurological deficit with each hemorrhagic event is high. Treatment of these patients at specialized centers is recommended to prevent neurological injury from a spontaneous ICH.