Posterior circulation infarcts in patients with vertebrobasilar dolichoectasia.

BACKGROUND AND PURPOSE

Vertebrobasilar dolichoectasia (VBD) may produce symptoms by direct compression of cranial nerves or the brain stem, by obstructive hydrocephalus, or by ischemia in the vertebrobasilar arterial territory. This study was undertaken to examine and characterize clinical and imaging findings in patients with stroke associated with VBD and compare these data with those for patients with VBD who did not have a stroke.

METHODS

We studied 40 consecutive stroke patients with associated VBD. All were evaluated by CT scan (n=9), MRI (n=6), or both (n=25). The diameter of the basilar artery (BA), height of bifurcation, and transverse position were evaluated. Clinical and imaging findings were compared with those found in a group of 40 VBD patients without stroke.

RESULTS

More than half of the patients (24 of 40) had infratentorial infarcts, located mainly in the midpons. Sixteen patients had supratentorial lesions localized in the thalamus (n=8) or in the superficial arterial territory of the posterior cerebral artery (PCA; n=8). The diameter and height of the bifurcation of the BA were correlated with the location of the lesion (PCA territory versus BA territory), in that severe ectasia and vertical elongation of the BA were significantly more often observed in patients with infarcts in PCA territory than in patients with infarcts in territories supplied by branches of the BA. Comparison of VBD patients with and without stroke showed that the incidence of arterial hypertension and the degree of ectasia and lateral displacement of the BA were not significantly different in the two groups. Patients with stroke more often had atherosclerotic changes of the posterior circulation (P=.0006) and a higher degree of vertical elongation of the BA (P=.025).

CONCLUSIONS

In patients with VBD, superimposed atheromatous changes of the posterior circulation may have an important role in precipitating ischemia. However, other factors related to the severity of the dolichoectasia also favor ischemia and in some cases are the only factors responsible.