Dose of Vestibular Rehabilitation for Vestibular Hypofunction

Disorders of vestibular function are prevalent disorders that result in dizziness, decreased balance, and a 12-fold increased risk of falls.1 It has been determined that 20% of community-dwelling adults over the age of 60 report vestibular symptoms prompting a medical evaluation or intervention over a one year period.2 This equates to approximately $50.0 billion in annual healthcare costs.3 In the US alone, there are approximately 1.6-3.8 million sport concussions each year,4,5 where 50% of concussed athletes have at least one vestibular type symptom.6 Although the impact of cost has been demonstrated in older adults, the costs of concussion-related dizziness is much more difficult to calculate due simultaneously treating symptoms from multiple systems.

A common treatment for symptoms related to disorders of vestibular function is vestibular rehabilitation, a sub-specialty of physical therapy. These exercises are performed daily by Subjects at home and consist of visually fixating on a target while moving the head and/or the object on which the subject is fixating. To alter exercise difficulty, exercise parameters are altered including: visual background complexity (plain and dark, busy but stationary, moving objects, rapidly moving objects), postural positioning (seated, standing with a wide base of support, standing with a narrow base of support, standing on one leg), and duration of exercise (from 5 seconds to approximately 2 minutes). Early evidence shows that vestibular rehabilitation exercises provided by a physical therapist is an effective method of ameliorating vestibular hypofunction. Further, effectiveness of vestibular rehabilitation does not decline with increasing age of the patient,8 indicating benefit for all ages that are affected. Unfortunately, many factors limit the ability to determine efficiency and efficacy of treatment and have been highlighted in a recent clinical practice guideline9 and systematic review5,10. Limitations include: poor measurement of prescribed exercise compliance by depending on subjective report, inability to control for environmental factors during home program execution, and the influence of noxious vestibular input associated with traveling to attend scheduled physical therapy visits. These factors hinder performing high quality efficacy studies, resulting in exercise prescription being largely based on expert opinion, the lowest level on the hierarchy of evidence-based practice.11 In fact, current opinion indicates that exercises should be performed 3 times a day for a total of 12 minutes with each bout lasting approximately 2 minutes, all with no clear indication of speed and amplitude of performance. In this study, the investigators aim to use a commercially available virtual reality device to deliver usual vestibular rehabilitation exercises, while using the device's inbuilt sensors to accurately measure head movement, speed and duration. Using this device, the investigators will assess compliance and dose of exercises required to reduce symptoms of dizziness and imbalance and to determine if performing such exercises in a virtual reality environment will provide similar results to that usual rehabilitation techniques.

When a potential subject is identified, the subject will be screened for appropriateness of inclusion for this study. After informed consent has been obtained from a recruited subject, those with Unilateral Vestibular Hypofunction (UVH) will be asked to perform a 4-week intervention, while those with Bilateral Vestibular Hypofunction (BVH) or those post-concussion will each be asked to perform a 12-week intervention. Those with UVH will undergo a shorter intervention due to strong evidence that neural adaptation occurs much more quickly (usually 4 weeks) than those with BVH and history of concussion.9,10,17-19 The intervention will consist of physical therapy visits combined with a home program of specific vestibular exercises. Each subject will be asked to attend physical therapy visits at least one time per week throughout the 4- or 12-week period.

Assessments will be performed on all groups and consist of a combination of vestibulo-ocular assessment, balance and clinical functional outcome measures, and surveys of subject satisfaction. Subjects are randomly assigned to the usual rehabilitation or intervention group based on each of the following diagnostic categories.

The compliance to exercises will be obtained from a log in the virtual reality device for the VR group, and will be paper based for the usual physical therapy group. Subjects in the three intervention groups will be asked to perform the same type of exercises as the usual rehabilitation group, but using a virtual reality device that will be issued to the patient for home use. Subjects will use a custom designed program to perform the exercises using a commercially available virtual reality device (no specialized hardware or additions to the commercially available device will be performed). Subjects will be instructed on the first day in how to operate the Virtual Reality Vestibular Rehabilitation (VRVR) program and how to properly perform the exercises. The VRVR device and software will simulate a virtual reality 'room' with an 'X' fixed in front of a wall. There are six different background complexities. Exercise sessions will start seated upright in a chair and will progress to standing per the home exercise protocol. The system will prompt the patient to begin the exercise and will automatically log the frequency and duration of exercise performed. The system will ask the patient to rate the severity of their symptoms on a 0-10 scale before and after each bout of exercise. Subjects' instruction regarding initial dose and progression will be identical to those given in the usual rehabilitation group. Subjects will be asked to bring their device with them to their 4 week, 8 week, and 12 weeks appointment to transfer their de-identified data and to insure integrity of the data and device. Subjects will be asked to return the device at the end of the intervention period.

Per patient and therapist discretion, additional physical therapy visits may be scheduled to aid in patient understanding of exercise progression protocol, assess correct performance of exercise (with or without virtual reality device). Non-study related physical therapy visits may be scheduled between sessions in order to address impairments unrelated to vestibulo-ocular deficits. These may include interventions to address musculoskeletal deficits or other balance related impairments. Any additional sessions of physical therapy will be reported in order to determine possible confounding information.

There will be an additional group of healthy control subjects that will be tested for only one day. Healthy subjects will be recruited through flyers, approved email lists, and word of mouth in the general public. This healthy control group will perform the same tests as the other groups perform on Day 1. This group will be used to compare outcomes of usual rehabilitation and intervention groups, to the function of those without disorders of vestibular function.