Clinical Significance of Vertebral Artery Hypoplasia in Lateral Medullary Infarction

ABSTRACT

OBJECTIVE: The clinical significance of vertebral artery hypoplasia (VAH) and the possible pathomechanism of lateral medullary infarction in patients with VAH are still not completely clear. METHODS: Among 3,968 patients with acute ischemic stroke, we selected 102 patients with lateral medullary infarction (2.6% [102/ 3,968]; 67 men, 35 women; mean age, 66 years; range, 33 to 86 years) who underwent brain magnetic resonance imaging, contrastenhanced magnetic resonance angiography, and transcranial Doppler (TCD) within 1 week of symptom onset. We compared the characteristics of VAH and non-VAH group. RESULTS: Of 102 patients with lateral medullary infarction, 34 (33.3%) had hypoplastic vertebral artery and 68 (66.7%) were non-VAH. The location of stroke in patients with right-sided VAH (n=22) was predominantly ipsilateral and in the 12 patients with left-sided VAH, the stroke was predominantly ipsilateral. TCD parameters of Mean flow velocity and pulsatility index were significantly different on the affected side between VAH and non-VAH groups (P < 0.001). Patients having dominant vertebral artery is opposite to basilar artery curvature are 88.2% (30/34). CONCLUSION: We concluded that VAH can be considered an additional risk factor for lateral medullary infarction. The influence of reduced blood flow in the hypoplastic vertebral artery is also important to consider, especially when other vascular risk factor are present. The presence of dolichoectasy of the basilar artery ipsilateral to the VAH causes reorganization of the blood flow around the vertebrobasilar junction.