Contribution of intracranial vertebral artery asymmetry to vestibular neuropathy.
OBJECTIVE
To test the hypothesis that vertebral artery hypoplasia (VAH) may affect the lateralisation of vestibular neuropathy (VN), probably through haemodynamic effect on the vestibular labyrinth.


METHODS
69 patients with unilateral VN were examined with a magnetic resonance angiographic (MRA) and caloric test. 50 healthy subjects served as controls. The diagnosis of intracranial VAH was based on MRA if <0.22 cm in VA diameter and a diameter asymmetry index >40%. The authors then correlated the canal paretic side with the VAH side.


RESULTS
MRA study revealed 29 VAH (right/left: 23/6) in VN subjects and six VAH in controls (right/left: 5/1). The RR of VAH in VN subjects compared with controls was elevated (RR=2.2; 95% CI 1.8 to 2.8). There was a high accordance rate between the side of VAH and VN. Among 29 patients with unilateral VAH, 65.5% (N=19) had an ipsilateral VN, in which left VAH showed a higher accordance rate (83.3%) than the right side (60.9%). VN subjects with vascular risk factors also had a higher VAH accordance rate (81%) than those without (25%).


CONCLUSIONS
VAH may serve as a regional haemodynamic negative contributor and impede blood supply to the ipsilateral vestibular labyrinth, contributing to the development of VN, which could be enhanced by atherosclerotic risk factors and the left-sided location.
Chuang
Y M
YM
Department of Neurology, Taipei Veterans General Hospital, Taipei, Taiwan, Republic of China.
Chern
C M
CM
Liao
W H
WH
Hsu
L C
LC
Lien
C F
CF
Lirng
J F
JF
Shiao
A S
AS
Ko
J S C
JS
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002150:Caloric Tests; D004311:Double-Blind Method; D004424:Ear Canal / Q000473:pathology; D007758:Ear, Inner / Q000098:blood supply / Q000473:pathology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007511:Ischemia / Q000209:etiology / Q000473:pathology; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014711:Vertebral Artery / Q000473:pathology*; D020338:Vestibular Neuronitis / Q000473:pathology*; D014722:Vestibule, Labyrinth / Q000098:blood supply / Q000473:pathology