Theoretical framework for "unexplained" dizziness in the elderly: The role of small vessel disease.

In this paper we postulate that disruption of connectivity in the human brain can lead to dizziness, a symptom normally associated with focal disease of the vestibular system. The specific case that we will examine is the development of "unexplained" dizziness in the elderly-an extremely common clinical problem. Magnetic resonance imaging of the brain in the elderly usually show variable degrees of multifocal micro-angiopathy (small vessel white matter disease, SVD); thus, we review the literature, present a conceptual model and report preliminary quantitative EEG data in support of the hypothesis that such hemispheric SVD leads to central nervous system disconnection that elderly patients report as dizziness. Loss of connectivity by age-related build-up of SVD could lead to dizzy feelings through one or more of the following mechanisms: disconnection of cortical vestibular centers, disconnection between frontal gait centers and the basal ganglia, and disconnection between intended motor action (efference copy) and sensory re-afference. Finally, we propose that SVD-mediated dysregulation of cerebral blood pressure is linked to dizziness during standing and walking in elderly patients with "unexplained" dizziness.