The human brain networks mediating the vestibular sensation of self-motion

Treating benign paroxysmal positional vertigo in acute traumatic brain injury: a prospective, randomised clinical trial assessing safety, feasibility, and efficacy

Background

Benign paroxysmal positional vertigo (BPPV) affects approximately half of acute, moderate-severe traumatic brain injury (TBI) patients. To date, there have been no rigorous studies of BPPV assessment or treatment in this cohort. We aimed to determine the safety, practicability, and efficacy of therapist-led BPPV management in acute TBI and the feasibility of a larger effectiveness trial.

Methods

This was a multi-centre, three-arm, parallel-groups, randomised, feasibility trial. Recruitment was via convenience sampling. The main inclusion criteria were age over 18 years and a confirmed, non-penetrating, acute TBI. BPPV-positive patients were randomly allocated to one of three interventions (repositioning manoeuvres, Brandt-Daroff exercises or advice) using minimisation criteria. Outcome assessors were blinded to the intervention.

Results

Of 2014 patients screened for inclusion, 180 were assessed for BPPV. Of those assessed, 34% (62/180) had BPPV, and 58 patients received an intervention. Therapist-led interventions were delivered safely and accurately according to intervention monitoring criteria. Resolution of BPPV was observed in 35/58 (60%) patients. The resolution rate was highest following repositioning manoeuvres (78%), followed by the advice (53%) and Brandt-Daroff interventions (42%). 10 patients experienced recurrence. This was observed more frequently in those with skull fractures and bilateral or mixed BPPV.

Conclusions

Overall, the results provide strong evidence for the feasibility of a future trial. Therapist-led management of BPPV in acute TBI was safe and practicable. Repositioning manoeuvres seemingly yielded a superior treatment effect. However, given the high recurrence rate of post-traumatic BPPV, the optimal time to treat according to patients' specific recurrence risk requires further investigation.

Trial registration

ISRCTN91943864, https://doi.org/10.1186/ISRCTN91943864.

Illusions of Self-Motion during Magnetic Resonance-Guided Focused Ultrasound Thalamotomy for Tremor

OBJECTIVE

Brain networks mediating vestibular perception of self-motion overlap with those mediating balance. A systematic mapping of vestibular perceptual pathways in the thalamus may reveal new brain modulation targets for improving balance in neurological conditions.

METHODS

Here, we systematically report how magnetic resonance-guided focused ultrasound surgery of the nucleus ventralis intermedius of the thalamus commonly evokes transient patient-reported illusions of self-motion. In 46 consecutive patients, we linked the descriptions of self-motion to sonication power and 3-dimensional (3D) coordinates of sonication targets. Target coordinates were normalized using a standard atlas, and a 3D model of the nucleus ventralis intermedius and adjacent structures was created to link sonication target to the illusion.

RESULTS

A total of 63% of patients reported illusions of self-motion, which were more likely with increased sonication power and with targets located more inferiorly along the rostrocaudal axis. Higher power and more inferiorly targeted sonications increased the likelihood of experiencing illusions of self-motion by 4 and 2 times, respectively (odds ratios = 4.03 for power, 2.098 for location).

INTERPRETATION

The phenomenon of magnetic vestibular stimulation is the most plausible explanation for these illusions of self-motion. Temporary unilateral modulation of vestibular pathways (via magnetic resonance-guided focused ultrasound) unveils the central adaptation to the magnetic field-induced peripheral vestibular bias, leading to an explicable illusion of motion. Consequently, systematic mapping of vestibular perceptual pathways via magnetic resonance-guided focused ultrasound may reveal new intracerebral targets for improving balance in neurological conditions. ANN NEUROL 2024.

We should be screening for benign paroxysmal positional vertigo (BPPV) in all older adults at risk of falling: a commentary on the World Falls Guidelines

Benign paroxysmal positional vertigo (BPPV) is amongst the commonest causes of dizziness and falls in older adults. Diagnosing and treating BPPV can reduce falls, and thereby reduce fall-related morbidity and mortality. Recent World Falls Guidelines recommend formal assessment for BPPV in older adults at risk of falling, but only if they report vertigo. However, this recommendation ignores the data that (i) many older adults with BPPV experience dizziness as vague unsteadiness (rather than vertigo), and (ii) others may experience no symptoms of dizziness at all. BPPV without vertigo is due to an impaired vestibular perception of self-motion, termed 'vestibular agnosia'. Vestibular agnosia is found in ageing, neurodegeneration and traumatic brain injury, and results in dramatically increased missed BPPV diagnoses. Patients with BPPV without vertigo are typically the most vulnerable for negative outcomes associated with this disorder. We thus recommend simplifying the World Falls Guidelines: all older adults (>60 years) with objective or subjective balance problems, irrespective of symptomatic complaint, should have positional testing to examine for BPPV.

The Bárány Society position on 'Cervical Dizziness'

This paper describes the Bárány Society Classification OverSight Committee (COSC) position on Cervical Dizziness, sometimes referred to as Cervical Vertigo. This involved an initial review by a group of experts across a broad range of fields, and then subsequent review by the Bárány Society COSC. Based upon the so far published literature, the Bárány Society COSC takes the view that the evidence supporting a mechanistic link between an illusory sensation of self-motion (i.e. vertigo - spinning or otherwise) and neck pathology and/or symptoms of neck pain - either by affecting the cervical vertebrae, soft tissue structures or cervical nerve roots - is lacking. When a combined head and neck movement triggers an illusory sensation of spinning, there is either an underlying common vestibular condition such as migraine or BPPV or less commonly a central vestibular condition including, when acute in onset, dangerous conditions (e.g. a dissection of the vertebral artery with posterior circulation stroke and, exceedingly rarely, a vertebral artery compression syndrome). The Committee notes, that migraine, including vestibular migraine, is by far, the commonest cause for the combination of neck pain and vestibular symptoms. The committee also notes that since head movement aggravates symptoms in almost any vestibular condition, the common finding of increased neck muscle tension in vestibular patients, may be linked as both cause and effect, to reduced head movements. Additionally, there are theoretical mechanisms, which have not been explored, whereby cervical pain may promote vaso-vagal, cardio-inhibitory reflexes and hence by presyncopal mechanisms, elicit   transient   disorientation and/or imbalance. The committee accepts that further research is required to answer the question as to whether those rare cases in which neck muscle spasm is associated with a vague sense of spatial disorientation and/or imbalance, is indeed linked to impaired neck proprioception. Future studies should ideally be placebo controlled and double-blinded where possible, with strict inclusion and exclusion criteria that aim for high specificity at the cost of sensitivity. To facilitate further studies in "cervical dizziness/vertigo", we provide a narrative view of the important confounds investigators should consider when designing controlled mechanistic and therapeutic studies. Hence, currently, the Bárány COSC refrains from proposing any preliminary diagnostic criteria for clinical use outside a research study. This position may change as new research evidence is provided.