Rotational compression of the vertebral artery at the point of dural penetration. Case report.

Vertebrobasilar insufficiency (VBI) due to vertebral artery (VA) compression occurs in a significant number of patients. Rotational compression of the VA usually occurs below C-2, where the artery is pinched during head rotation, leading to thrombus formation and subsequent cerebellar infarction. Although this problem has been reported to occur at the atlantooccipital levels, a review of the literature revealed no published cases of VA compression at the point of dural penetration, which is located above the atlantooccipital membrane. The authors report the case of a 30-year-old woman who presented with signs and symptoms of VBI. Dynamic angiography demonstrated left-sided VA compression at the site at which dural penetration had occurred, proximal to the posterior inferior cerebellar artery. Surgical decompression of the left VA at the point of dural penetration relieved the symptoms, and postoperative dynamic angiography demonstrated complete resolution of the positional compression of the left VA. Because of these findings, an additional possible location for rotational compression of the VA is described, namely, the point of dural penetration. The authors suggest a method of surgically treating rotational VA compression at this site.