Non-pharmacological interventions for persistent postural-perceptual dizziness (PPPD)

BACKGROUND: Persistent postural-perceptual dizziness (PPPD) is a chronic balance disorder, which is characterised by subjective unsteadiness or dizziness that is worse on standing and with visual stimulation. The condition was only recently defined and therefore the prevalence is currently unknown. However, it is likely to include a considerable number of people with chronic balance problems. The symptoms can be debilitating and have a profound impact on quality of life. At present, little is known about the optimal way to treat this condition. A variety of medications may be used, as well as other treatments, such as vestibular rehabilitation.  OBJECTIVES: To assess the benefits and harms of non-pharmacological interventions for persistent postural-perceptual dizziness (PPPD).  SEARCH METHODS: The Cochrane ENT Information Specialist searched the Cochrane ENT Register; Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE; Ovid Embase; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 21 November 2022. SELECTION CRITERIA: We included randomised controlled trials (RCTs) and quasi-RCTs in adults with PPPD, which compared any non-pharmacological intervention with either placebo or no treatment. We excluded studies that did not use the Bárány Society criteria to diagnose PPPD, and studies that followed up participants for less than three months.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were: 1) improvement in vestibular symptoms (assessed as a dichotomous outcome - improved or not improved), 2) change in vestibular symptoms (assessed as a continuous outcome, with a score on a numerical scale) and 3) serious adverse events. Our secondary outcomes were: 4) disease-specific health-related quality of life, 5) generic health-related quality of life and 6) other adverse effects. We considered outcomes reported at three time points: 3 to < 6 months, 6 to ≤ 12 months and > 12 months. We planned to use GRADE to assess the certainty of evidence for each outcome.  MAIN RESULTS: Few randomised controlled trials have been conducted to assess the efficacy of different treatments for PPPD compared to no treatment (or placebo). Of the few studies we identified, only one followed up participants for at least three months, therefore most were not eligible for inclusion in this review.  We identified one study from South Korea that compared the use of transcranial direct current stimulation to a sham procedure in 24 people with PPPD. This is a technique that involves electrical stimulation of the brain with a weak current, through electrodes that are placed onto the scalp. This study provided some information on the occurrence of adverse effects, and also on disease-specific quality of life at three months of follow-up. The other outcomes of interest in this review were not assessed. As this is a single, small study we cannot draw any meaningful conclusions from the numeric results.  AUTHORS' CONCLUSIONS: Further work is necessary to determine whether any non-pharmacological interventions may be effective for the treatment of PPPD and to assess whether they are associated with any potential harms. As this is a chronic disease, future trials should follow up participants for a sufficient period of time to assess whether there is a persisting impact on the severity of the disease, rather than only observing short-term effects.