Mystery blood vessel disorder implicated in ’mini’ strokes

Physicians have long been puzzled by a condition called intracranial arterial dolichoectasia, in which the larger arteries of the brain become elongated and misshapen. Typically, it has been considered a complication of atherosclerosis (“hardening of the arteries”), and not directly life-threatening. However, there is recent evidence that people with dolichoectasia are more likely to have aortic aneurysms, a potentially fatal weakening of the main artery that carries blood out from the heart. In an article published online February 28, 2005 in the Annals of Neurology the same French researchers who linked dolichoectasia with aortic aneurysm reveal new evidence that links the disorder with small vessel disease, a significant cause of lacunar or “mini” strokes that can damage small areas of the brain.

Depending on which area of the brain is affected, the strokes can impair functions such as movement, physical control of speech, or coordination. Multiple lacunar strokes can also cause cognitive and memory deficits that resemble Alzheimer’s disease.

According to the authors, physicians who encounter patients with small vessel disease should look for evidence of dolichoectasia. “If dolichoectasia is present, you should look for an associated abdominal aortic aneurysm and carefully search for associated cardiac symptoms,” said author Pierre Amarenco, M.D., of Bichat University Hospital in Paris.

Beyond the immediate clinical implications, the study may offer more important clues for further research. It may be that dolichoectasia causes or contributes to small vessel disease, and/or that the two have common causes.

Nearly a quarter of all strokes arise from blood flow problems in the smallest blood vessels of the brain. Patients with the disease are usually found to have high blood pressure, but the causes of the disease are unknown.

Using MRI, Amarenco and his colleagues studied 510 patients who had suffered strokes and found that the subset of patients with dolichoectasia were more likely to have evidence of small vessel disease. Indeed, there was a direct relationship between the diameter of the basilar artery, the cranial artery most often affected in dolichoectasia, and the severity of small vessel disease.

“This study is the first to show an association between intracranial arterial dolichoectasia and the whole spectrum of small vessel disease abnormalities, thus defining a new cerebrovascular syndrome,” said Amarenco.

The researchers will continue to follow the patients in this study (the GENIC study) to try to determine which vascular or genetic factors contribute to the syndrome. They will also attempt to replicate their MRI data in an autopsy study of patients who died with dolichoectasia.