Evaluation of Rotational Vertebral Artery Occlusion Using Ultrasound Facilitates the Detection of Arterial Dissection in the Atlas Loop.

PURPOSE: Head rotation can cause occlusion of the vertebral artery most commonly at the atlas loop, and repetitive compression from head turning induces vertebral artery dissection (VAD). Although ultrasound examinations are useful in diagnosis, dissected lesions unaccompanied by hemodynamic changes can be overlooked. Because the narrowed, dissected vessel in the atlas loop may cause rotational occlusion, we confirmed whether adding submaximal head rotation to a cervical ultrasound examination would facilitate the detection of VAD in the atlas loop. METHODS: We investigated 7 patients who developed infarction in the posterior circulation and were clinically suspected of VAD. Using a 7.5-MHz linear probe, we recorded the waveform of the vertebral artery at the C4-C6 level and diagnosed rotational vertebral artery occlusion (RVAO) when head rotation induced the disappearance of end-diastolic flow. RESULTS: All 3 patients with VAD in the atlas loop demonstrated RVAO of the dissected vertebral arteries in the acute stroke phase. RVAO was not observed in the dissected vertebral arteries excepting the atlas loop, nor in the nondissected vertebral arteries of any patients. CONCLUSION: For posterior circulation stroke patients, adding submaximal head rotation to the cervical ultrasound examination facilitated the detection of VAD in the atlas loop.