Recurring paroxysmal positional vertigo: evaluation of the vascular factor

To evaluate the effective incidence of vascular factor in the recurrence of benign paroxysmal positional vertigo (BPPV), we studied 50 subjects, 32 affected by idiopathic recurrent BPPV (study group) and 18 healthy subjects (control group). All subjects underwent complete otoneurological balance and haemodynamic evaluation by extracranial colour-coded duplex sonography (ECCS) of vertebral arteries (VA) with indication of arterial flow in ml/min, and retinal fluorangiography (FAG). The ECCS of 19 patients (59.3%) within the study group presented a reduction in vertebral arterial flow, exceeding the limits established by normative values (< 100 ml/min). In all cases, the same side was affected by BPPV, emphasised by vertebral hypoperfusion. The remaining 13 patients (40.6%) showed an arterial vertebral flow entirely within the normative values. The FAG excluded qualitative alterations of the cerebral microcirculation. The ECCS demonstrated that 59.3% of the study group showed a significant reduction in vertebral arterial flow ipsilateral to the semicircular canal affected by BPPV. This increased to 68.75% when the flow difference (D) between both the vertebral arteries were considered and reached 71.8% when vascular risk factors were evaluated. We conclude that reduced perfusion of the vestibular structures makes an already critical situation even more difficult, which can eventually develop into labyrinth suffering. The absence of fluorangiographic signs suggests that the labyrinthine neuroepithelium is much more sensitive to hypoperfusion than the retina. We hypothesise that this ischaemic situation could degenerate utricular macula, otolith detachment, leading to the development of recurrent BPPV. This risk situation for the labyrinth can also be revealed by the evaluation of three parameters: presence of vascular risk factors, reduction of vertebral flow < 100 ml/min and the difference in flow between the 2 vertebral arteries > 29 ml/min.