Acute rotatory vertigo caused by a small haemorrhage of the vestibular cortex

Localization of Vestibular Cortex Using Electrical Cortical Stimulation: A Systematic Literature Review

The vestibular system plays a fundamental role in body orientation, posture control, and spatial and body motion perception, as well as in gaze and eye movements. We aimed to review the current knowledge regarding the location of the cortical and subcortical areas, implicated in the processing of vestibular stimuli. The search was performed in PubMed and Scopus. We focused on studies reporting on vestibular manifestations after electrical cortical stimulation. A total of 16 studies were finally included. Two main types of vestibular responses were elicited, including vertigo and perception of body movement. The latter could be either rotatory or translational. Electrical stimulation of the temporal structures elicited mainly vertigo, while stimulation of the parietal lobe was associated with perceptions of body movement. Stimulation of the occipital lobe produced vertigo with visual manifestations. There was evidence that the vestibular responses became more robust with increasing current intensity. Low-frequency stimulation proved to be more effective than high-frequency in eliciting vestibular responses. Numerous non-vestibular responses were recorded after stimulation of the vestibular cortex, including somatosensory, viscero-sensory, and emotional manifestations. Newer imaging modalities such as functional MRI (fMRI), Positron Emission Tomography (PET), SPECT, and near infra-red spectroscopy (NIRS) can provide useful information regarding localization of the vestibular cortex.

Rotatory Vertigo Caused by a Small Hemorrhage in the Superior Temporal Gyrus

Rotatory vertigo is known to have not only peripheral causes, e.g., Meniere's disease, vestibular neuritis, and benign paroxysmal positional vertigo, but also central causes, e.g., stroke, hemorrhage, and tumor. In most cases, central rotatory vertigo is caused by a lesion in the brainstem or cerebellum, but rare cases with a cerebral lesion have also been reported. We herin describe a unique case with acute rotatory vertigo following a small hemorrhage in the left superior temporal gyrus, which probably led to a dysfunction of the visual-vestibular system.

Isolated rotational vertigo due to internal capsular infarction

Isolated rotational vertigo is most often associated with disorders of the semicircular canals, vestibular nerve, brainstem, or cerebellum but rarely observed following a supratentorial stroke. A 64-year-old man developed sudden onset of vertigo and horizontal right-beating nystagmus with a torsional component in primary and eccentric gazes, unsteady gait, and axial lateropulsion to the right side. Magnetic resonance imaging demonstrated an infarction in the posterior limb of left internal capsule, an unusual cause of the patient's signs and symptoms.

Rotational vertigo associated with putaminal infarction

A 57-year-old man was admitted because of left hemiparesis. A magnetic resonance imaging scan of the brain revealed a recent infarct from the dorsal side of the right putamen to the corona radiata. Three hours after onset, he complained of rotational vertigo. Truncal ataxia was also found on standing a few days later, which persisted until the chronic phase. Repeat magnetic resonance imaging scans on days 2 and 11 revealed no additional lesions. The present case indicates that rotational vertigo might result from a small, supratentorial, subcortical lesion.

The thalamocortical vestibular system in animals and humans

The vestibular system provides the brain with sensory signals about three-dimensional head rotations and translations. These signals are important for postural and oculomotor control, as well as for spatial and bodily perception and cognition, and they are subtended by pathways running from the vestibular nuclei to the thalamus, cerebellum and the "vestibular cortex." The present review summarizes current knowledge on the anatomy of the thalamocortical vestibular system and discusses data from electrophysiology and neuroanatomy in animals by comparing them with data from neuroimagery and neurology in humans. Multiple thalamic nuclei are involved in vestibular processing, including the ventroposterior complex, the ventroanterior-ventrolateral complex, the intralaminar nuclei and the posterior nuclear group (medial and lateral geniculate nuclei, pulvinar). These nuclei contain multisensory neurons that process and relay vestibular, proprioceptive and visual signals to the vestibular cortex. In non-human primates, the parieto-insular vestibular cortex (PIVC) has been proposed as the core vestibular region. Yet, vestibular responses have also been recorded in the somatosensory cortex (area 2v, 3av), intraparietal sulcus, posterior parietal cortex (area 7), area MST, frontal cortex, cingulum and hippocampus. We analyze the location of the corresponding regions in humans, and especially the human PIVC, by reviewing neuroimaging and clinical work. The widespread vestibular projections to the multimodal human PIVC, somatosensory cortex, area MST, intraparietal sulcus and hippocampus explain the large influence of vestibular signals on self-motion perception, spatial navigation, internal models of gravity, one's body perception and bodily self-consciousness.

Posterior parietal rTMS disrupts human Path Integration during a vestibular navigation task

In contrast to vision, the neuro-anatomical substrates of vestibular perception are obscure. The vestibular apparati provide a head angular velocity signal allowing perception of self-motion velocity. Perceived change of angular position-in-space can also be obtained from the vestibular head velocity signal via a process called Path Integration (so-called since displacement is obtained by a mathematical temporal integration of the vestibular velocity signal). It is unknown however, if distinct cortical loci sub-serve vestibular perceptions of velocity versus displacement (i.e. Path Integration). Previous studies of human brain activity have not used head motion stimuli hence precluding localisation of vestibular cortical areas specialised for Path Integration distinct from velocity perception. We inferred vestibular cortical function by measuring the disrupting effect of repetitive transcranial magnetic stimulation on the performance of a displacement-dependent vestibular navigation task. Our data suggest that posterior parietal cortex is involved in encoding contralaterally directed vestibular-derived signals of perceived angular displacement and a similar effect was found for both hemispheres. We separately tested whether right posterior parietal cortex was involved in vestibular-sensed velocity perception but found no association. Overall, our data demonstrate that posterior parietal cortex is involved in human Path Integration but not velocity perception. We suggest that there are separate brain areas that process vestibular signals of head velocity versus those involved in Path Integration.

Rotational vertigo associated with parietal cortical infarction

A 65-year-old woman experienced sudden positional vertigo with rightward, horizontal nystagmus that resolved within days. MRI revealed a left parietal lobe infarction involving the supramarginal gyrus. The patient experienced a transient recurrence of vertigo after 7 days but MRI failed to reveal the presence of any new lesions; furthermore, the patient's EEG was normal. We suggest that this patient's vertigo was due to her parietal cortical infarction.