Effect of vertebral artery hypoplasia on false negative rates in early MRI detection of small posterior circulation infarcts in elderly patients

Abstract

Objective To explore the effects of vertebral artery hypoplasia(VAH)on false-negative rates with MRI in isolated acute vestibular syndrome(AIVS)patients with small posterior circulation small infarcts(infarct diameter ≤10 mm by DWI). Methods A total of 224 AIVS patients with at least one stroke risk factor(defined as high-risk AIVS)were consecutively recruited.Head impulse, nystagmus and test-of-skew(HINTS), brainstem auditory evoked potential(BAEP), and blink reflex(BR)were performed as soon as possible ahead of MRI.Another MRI was carried out in those with negative findings on the first imaging but suspected of a central lesion based on HINTS+ BAEP+ BR.Patients were divided into a VAH group and a non-VAH group. Results Of the 98 cases with posterior circulation infarcts, 37 cases were small infarcts, including 16 in the VAH group(16/61, 26.2%)and 21 in the non-VAH group(21/163, 12.9%), with a significant difference between the groups(χ2=4.58, P<0.05). Nine VAH patients(9/16, 56.3%)and 4 non-VAH patients(4/21, 19.0%)presented false negative results on cranial MRI-DWI, and the difference was also statistically significant(χ2=6.23, P<0.001). HINTS + BAEP + BR showed a higher sensitivity than early MRI in identifying small infarcts(VAH group: 100.0% vs. 44.0% or 7/16, U=6.41, P<0.001; non-VAH group: 100.0% vs. 81.0% or 17/21, U=4.46, P<0.05). V wave peak latency, Ⅲ-Ⅴ and Ⅰ-Ⅴ wave interpeak latency, and the latency of R1, R2, and R2′ in the VAH group were longer than in the non-VAH group(each P<0.05). Conclusions When VAH is present in high-risk AIVS patients, small infarcts are common, with high false-negative rates on MRI-DWI.HINTS + BAEP + BR may help identify small infarcts and thus improve diagnostic sensitivity. Key words: Vertebral artery; Angiodysplasia; Brain infarction; Vestibular syndrome; Magnetic resonance imaging