Psychologically informed vestibular rehabilitation for persistent dizziness

Student thesis: Doctoral ThesisDoctor of Philosophy

Abstract

Vertigo or dizziness is not a disease, but rather a leading symptom of various underlying conditions. These include disorders of the vestibular system, which is responsible for our sense of balance and motion. Many people with vestibular system disorders experience persistent dizziness that can be particularly hard to treat. Vestibular rehabilitation therapy (VRT) is an established physiotherapy-based treatment for people with vestibular dysfunction, which tries to reduce dizziness and improve postural and gaze stability. However, the benefits are not universal and do not always correlate with physiological findings. Poor response to VRT may be because there are concomitant psychosocial factors contributing to the chronicity of the symptoms which are not addressed during VRT.

Previous studies have shown a correlation between dizziness and anxiety and depression. Studies of cognitive-behavioural therapy (CBT) for persistent dizziness have to date focused on reducing generalised anxiety to determine if this in turn relieves the dizziness symptoms. This appears to have limited or only short-term success. This may be because although anxiety and depression likely play a role in exacerbating symptoms, mood is only one factor in this multifactorial condition. Understanding a broader range of psychosocial factors specific to vestibular disorders may be needed to provide more tailored and targeted CBT. Combining this with VRT would provide an integrated approach to treating both physiological and psychological features of the disorder.
The central question of this thesis was to see whether we could design and evaluate the feasibility of an empirically derived theory-based ‘CBT informed’ vestibular rehabilitation intervention for people with persistent dizziness.

The project followed the Medical Research Council framework for developing and evaluating complex interventions. A systematic review of 89 studies using meta-analysis and narrative synthesis identified potentially modifiable psychosocial factors from existing research related to dizziness handicap and symptom severity. A longitudinal survey (n =185 pre diagnosis) was conducted to test the relationship between relevant psychological variables, clinical tests of vestibular deficits and dizziness handicap and subjective symptoms. The cross-sectional results showed that the psychological factors which included distress, negative illness perceptions, and unhelpful cognitive-behavioural responses to symptoms explained >50% of the variance in self-reported handicap and around 30% of the variance in symptom severity. Following diagnosis (n=135) an all-or-nothing erratic pattern of behaviour and experiencing symptoms for a longer time predicted higher dizziness handicap, although baseline ‘handicap’ was the strongest predictor. The results of the review and the survey, together with patient-public representation, informed the development of an integrated manual-based programme of ‘CBT informed’ vestibular rehabilitation, called INVEST, combining cognitive behavioural therapy and physical rehabilitation.
A parallel group randomised controlled pilot-feasibility trial was then conducted, with 40 participants with persistent dizziness who were randomly assigned to receive 6 sessions of INVEST (n=20) or current ‘gold standard’ VRT (n=20). Participants were individually randomised using a minimisation procedure with allocation concealment. Both interventions were delivered by specialist physiotherapists. Primary feasibility and self-report outcomes were collected at baseline and 4 months post randomisation.

A nested qualitative study was also conducted post-intervention to explore the acceptability of the intervention and identify any areas in need of improvement. This study demonstrated excellent acceptability and feasibility. The study met all the a-priori criteria to progress to a full-scale efficacy trial, including 80% of eligible patients participating (pre-defined criteria >70%), 15% therapy and 2.5% trial drop-out rates (criteria <20%), comparable acceptability ratings to current gold standard VRT, and 80% adherence to sessions (criteria >60%). Fifty-nine percent of patients screened met the selection criteria and the enrolment rate was 80%. According to the qualitative data and exploratory treatment effect sizes, the intervention appeared to be both acceptable and potentially beneficial.

This thesis improves our understanding of chronic vestibular symptoms. It provides invaluable information to inform a larger scale trial of an intervention that could potentially improve the quality of life of sufferers, above and beyond standard physiotherapy care. By delivering the intervention as part of physiotherapy, this in turn will improve the access to psychological therapies and use of available resources; reduce the need for patients to see more than one healthcare professional and allow clinicians to respond to patient preference. Improving the outcome of rehabilitation may have additional beneficial social and economic implications as the patient is able to better manage their condition. Given the high prevalence of persistent dizziness in audio-vestibular, neuro-otology, and VRT clinics there is a sufficient need, and number of patients, to run a fully powered RCT.
Date of Award1 Aug 2022
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorRona Moss-Morris (Supervisor), Marousa Pavlou (Supervisor) & Sam Norton (Supervisor)

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