Richard T. Ibitoye (United Kingdom)
Imperial College LOndon Brain SciencesAuthor Of 2 Presentations
FRONTAL WHITE MATTER INTEGRITY AND IDIOPATHIC DIZZINESS IN CEREBRAL SMALL VESSEL DISEASE
- Richard T. Ibitoye (United Kingdom)
Abstract
Background and Aims:
Three in ten older people (>60 years) complain of persistent dizziness which often remains unexplained despite specialist assessment and vestibular tests. The pathophysiology of such idiopathic dizziness in older people has remained unclear. We investigated if idiopathic dizziness was associated with vascular injury to white matter tracts relevant to balance or vestibular self-motion perception in sporadic small vessel disease.
Methods:
We prospectively recruited 38 vestibular clinic patients with idiopathic dizziness (median 77 years) and 36 asymptomatic controls (median 76 years) who underwent clinical, cognitive, balance, gait and vestibular assessments, and structural and diffusion brain MRI.
Results:
Patients had more vascular risk factors, poorer balance and worse executive cognitive function in association with greater white matter hyperintensity in frontal deep white matter, and lower fractional anisotropy in the genu of the corpus callosum and the right inferior longitudinal fasciculus. Tracts with lower fractional anisotropy in idiopathic dizziness overlapped with those in which lower fractional anisotropy correlated with worse balance across participants. More vestibular symptoms correlated with worse balance in patients. Vestibulo-ocular reflex and perceptual vestibular function was similar in patients and controls, though a white matter network involved in vestibular perception had lower connectivity in patients.
Conclusions:
Our results show a relationship between lower microstructural integrity in frontal balance-relevant white matter tracts in cerebral small vessel disease, poorer balance and idiopathic dizziness. This suggests cerebral small vessel disease may be involved in the pathogenesis of dizziness in some older people.
THE HUMAN VESTIBULAR CORTEX: FUNCTIONAL ANATOMY, CONNECTIVITY AND THE EFFECT OF PERIPHERAL VESTIBULAR DISEASE
- Richard T. Ibitoye (United Kingdom)
Abstract
Background and Aims:
Area OP2 in the posterior peri-sylvian cortex has been proposed to be the core human vestibular cortex. We aimed to clarify the functional anatomy and connectivity of this area.
Methods:
We defined the functional anatomy of OP2 from high resolution functional MRI using spatially constrained independent component analysis on data from the Human Connectome Project. OP2 responses to caloric irrigation and visual motion were then investigated in seventeen controls and seventeen age-matched chronic right vestibular neuritis patients.
Results:
Ten distinct subregions were identified on the basis of varying functional connectivity. Most subregions showed significant connectivity to known vestibular areas, including the parietal opercula, the primary somatosensory cortex, the supracalcarine cortex, the left inferior parietal lobule and the anterior cingulate cortex. In healthy participants, a posterior part of right OP2 showed: (a) direction-selective responses to visual motion; and (b) activation during caloric stimulation that correlated positively with dizziness (perceived self-motion) and negatively with visual dependence. Patients with vestibular neuritis showed abnormal OP2 activity, with an absence of visual or caloric activation and no correlations with dizziness or visual dependence. In contrast, brainstem responses to caloric stimulation measured by peak slow phase nystagmus velocity were normal in the vestibular neuritis patients. A lateral part of right OP2 showed activity that correlated with situational vertigo (chronic dizziness) in patients with vestibular neuritis.
Conclusions:
A posterior subregion of right OP2 shows strong functional connectivity to other vestibular regions and a profile of caloric and visual responses, suggesting a central role for vestibular function in health and disease.
Presenter of 2 Presentations
FRONTAL WHITE MATTER INTEGRITY AND IDIOPATHIC DIZZINESS IN CEREBRAL SMALL VESSEL DISEASE
- Richard T. Ibitoye (United Kingdom)
Abstract
Background and Aims:
Three in ten older people (>60 years) complain of persistent dizziness which often remains unexplained despite specialist assessment and vestibular tests. The pathophysiology of such idiopathic dizziness in older people has remained unclear. We investigated if idiopathic dizziness was associated with vascular injury to white matter tracts relevant to balance or vestibular self-motion perception in sporadic small vessel disease.
Methods:
We prospectively recruited 38 vestibular clinic patients with idiopathic dizziness (median 77 years) and 36 asymptomatic controls (median 76 years) who underwent clinical, cognitive, balance, gait and vestibular assessments, and structural and diffusion brain MRI.
Results:
Patients had more vascular risk factors, poorer balance and worse executive cognitive function in association with greater white matter hyperintensity in frontal deep white matter, and lower fractional anisotropy in the genu of the corpus callosum and the right inferior longitudinal fasciculus. Tracts with lower fractional anisotropy in idiopathic dizziness overlapped with those in which lower fractional anisotropy correlated with worse balance across participants. More vestibular symptoms correlated with worse balance in patients. Vestibulo-ocular reflex and perceptual vestibular function was similar in patients and controls, though a white matter network involved in vestibular perception had lower connectivity in patients.
Conclusions:
Our results show a relationship between lower microstructural integrity in frontal balance-relevant white matter tracts in cerebral small vessel disease, poorer balance and idiopathic dizziness. This suggests cerebral small vessel disease may be involved in the pathogenesis of dizziness in some older people.
THE HUMAN VESTIBULAR CORTEX: FUNCTIONAL ANATOMY, CONNECTIVITY AND THE EFFECT OF PERIPHERAL VESTIBULAR DISEASE
- Richard T. Ibitoye (United Kingdom)
Abstract
Background and Aims:
Area OP2 in the posterior peri-sylvian cortex has been proposed to be the core human vestibular cortex. We aimed to clarify the functional anatomy and connectivity of this area.
Methods:
We defined the functional anatomy of OP2 from high resolution functional MRI using spatially constrained independent component analysis on data from the Human Connectome Project. OP2 responses to caloric irrigation and visual motion were then investigated in seventeen controls and seventeen age-matched chronic right vestibular neuritis patients.
Results:
Ten distinct subregions were identified on the basis of varying functional connectivity. Most subregions showed significant connectivity to known vestibular areas, including the parietal opercula, the primary somatosensory cortex, the supracalcarine cortex, the left inferior parietal lobule and the anterior cingulate cortex. In healthy participants, a posterior part of right OP2 showed: (a) direction-selective responses to visual motion; and (b) activation during caloric stimulation that correlated positively with dizziness (perceived self-motion) and negatively with visual dependence. Patients with vestibular neuritis showed abnormal OP2 activity, with an absence of visual or caloric activation and no correlations with dizziness or visual dependence. In contrast, brainstem responses to caloric stimulation measured by peak slow phase nystagmus velocity were normal in the vestibular neuritis patients. A lateral part of right OP2 showed activity that correlated with situational vertigo (chronic dizziness) in patients with vestibular neuritis.
Conclusions:
A posterior subregion of right OP2 shows strong functional connectivity to other vestibular regions and a profile of caloric and visual responses, suggesting a central role for vestibular function in health and disease.