Arteriovenous Malformations and Other Vascular Anomalies

[Unruptured brain arteriovenous malformations]

Cerebral arteriovenous malformations (AVMs) often become symptomatic in young adults with a variety of neurological symptoms such as epileptic seizures, recurrent headaches, progressive neurological deficits or sudden intracranial hemorrhage. However, recent epidemiological data suggest a large number of AVMs are found without signs of hemorrhage and a relatively low rupture risk of less than 1% per year. Continuous technical progress has led to several specific treatment options for brain AVMs including endovascular embolization, microneurosurgery, and stereotactic radiotherapy, either alone or in any combination. Depending on AVM topography and vascular anatomy, interventional treatment strategies have shown successful occlusion rates ranging between 50 and 100% and a relatively low average procedural morbidity of 10% overall. For unruptured brain AVMs, however, the clinical benefit of invasive treatment remains as yet to be determined. To address this issue, A randomized trial of unruptured brain AVMs (ARUBA) is currently underway evaluating long-term outcome of best possible standard interventional therapy as compared to the natural history risk in a prospective multidisciplinary international study (www.arubastudy.org).

Diffusion tensor imaging analysis of long association bundles in the presence of an arteriovenous malformation

OBJECT

Conventional imaging demonstrates intertwined fibers of the cerebral white matter as a homogeneous substrate. Recently, diffusion tensor imaging has allowed 3D reconstruction of these fiber bundles. The goal of this study was to analyze the modifications of the association fibers induced by an arteriovenous malformation (AVM) in the parietotemporooccipital (PTO) associative area and their clinical significance.

METHODS

The authors analyzed the long association fibers in seven patients harboring an AVM in or near the PTO region in relation with the fibers' clinical manifestation. The fibers include the arcuate fasciculus (AF), the occipitofrontal fasciculus (OFF), and the inferior longitudinal fasciculus (ILF). These structures were compared with the contralateral bundles.

RESULTS

The modification of the tracts could establish a pattern signature depending on the specific location of the vascular malformation. There was a positive correlation between the degree of modifications of OFF and ILF fiber tracts and visual deficits. Alteration of the AF correlated with a speech disorder and the risk of postoperative deficits.

CONCLUSIONS

Diffusion tensor imaging enables in vivo dissection of fiber tracts coursing through the PTO area. Depending on the location of the AVMs, long association fibers are variously modified. These findings correlate with clinical manifestations and may predict outcome after surgery.