Vertebral artery anomaly with atraumatic dissection causing thromboembolicischemia - A case report

Study Design. A case report is presented. Objectives. To illustrate a rare cause of atraumatic vertebral artery disse ction resulting from anomalous entry of the vessel at. the C3 transverse fo ramen induced by normal physiologic head and neck motion, and to review ver tebral artery anatomy and mechanisms whereby it is vulnerable to pathologic compression. Summary of Background Data. The vertebral artery usually enters the transve rse foramen at C6. Rarely, the artery enters at C5 or C4. Only one prior ca se with entry at C3 has been reported. That patient experienced recurrent q uadriplegia and locked-in syndrome caused by vertebral artery obstruction. A 27-year-old woman with a history of classic migraine experienced neurolog ic symptoms on three occasions related to physiologic neck and arm movement s. Magnetic resonance angiogram was not diagnostic, but standard arteriogra phy demonstrated anomalous vertebral artery entry into the C3 transverse fo ramen and focal dissection. Methods. Pertinent literature and the patient's history, physical examinati on, and radiologic studies were reviewed. Results. Standard cervico-cerebral arteriogram demonstrated focal dissectio n at C4 and thromboembolic complications in distal vertebral and basilar ar teries. Initially, diagnosis by magnetic resonance angiogram was illusive. However, arteriography allowed prompt diagnosis followed by anticoagulation with resolution of neurologic symptoms. Conclusions. Vertebral artery dissection without trauma is rare, but should be considered when neurologic symptoms accompany physiologic cervical move ments. For cases in which vertebrobasilar thromboembolic ischemia is suspec ted, magnetic resonance angiogram may prove inadequate for demonstrating th e causative vascular pathology. Therefore, standard cervico-cerebral arteri ography should be performed.