Can Wearable Sensors Help Patients with Vestibular Disorders?

A vestibular disorder is any malfunction of the inner ear or central nervous system that creates a feeling of dizziness, vertigo or disequilibrium. Vestibular disorders are a much larger problem than merely “being clumsy” or “feeling off-balance”; they can have a truly devastating effect on patients and dramatically decrease their quality of life.

It’s difficult to guess how many people have a vestibular disorder, but some estimates are as high as 35 percent of Americans age 40 and older.

Despite the commonness of these disorders, the ability to test for them and rehabilitate patients is woefully inadequate. This is why researchers Sathish K. Sankarpandi, Alice J. Baldwin, Jaydip Ray and Claudia Mazzà set out to find whether wearable sensors and software programs, such as the Opal sensors and Mobility Lab software from APDM Wearable Technologies, can help clinicians assess and rehabilitate their vestibular patients.

The Current State of Diagnostic Testing

Currently, traditional posture and balance tests occur in an artificial lab environment. Most only estimate vestibular function, rather than tracking accurate, real-time movement. Because there is such a disconnect between lab conditions and real life, these tests are highly inaccurate.

There are currently four main traditional diagnostic tests. These include:

Electronystagmography (ENG) – tracks eye movement with electrodes

Videonystagmography (VNG) – tracks eye movement with video goggles

Rotation test – tracks eye movement as the head is being rotated

Computerized Dynamic Posturography (CDP) – simulates a confusing visual/tactile scenario where the floor or the patient’s standing platform is moved and pressure readings are taken to measure balance and posture

As one can imagine, many of these tests are quite dizzying, disorienting and uncomfortable for vestibular patients, especially CDP, which requires them to wear a harness to prevent falls. Using wearable sensors to monitor patients’ day-to-day activities instead of subjecting them to lab testing could potentially make the diagnosis and monitoring of vestibular disorders easier and less stressful.

Purpose of the Study

The researchers wanted to see whether using Opal sensors and Mobility Lab software to instrument two standardized tests – Timed Up and Go (TUG) and postural sway (Sway) – could benefit vestibular patients and practitioners in a clinical setting, especially compared to traditional tests.

The researchers had three main questions:

  1. Are these sensors and tests feasible to use in a clinical setting?
  2. Will the sensors and tests produce test-retest reliable outcome measures for diagnosing and monitoring vestibular disorders?
  3. Can these outcome measures accurately distinguish between fallers and non-fallers?

This was a preliminary study meant to explore the potential application of these tools and the reliability of the test parameters before conducting a full-scale study. As such, the current study had a relatively small sample size and did not include a hypothesis.

Participants

There were 27 participants, all of which had sought the help of the Neurotology Clinics and had received a diagnosis of either a unilateral labyrinthine weakness or bilateral labyrinthine loss. The group was comprised of 20 females and seven males, all ranging in age from 40 to 81.

Five people were also recruited to be the test operators for this study. They were responsible for attaching the wearable sensors, administering the test and downloading the mobility data. While they weren’t tested for posture, gait or balance, their questionnaire results helped determine the feasibility of the sensors and tests.

Measurement Tools

The researchers conducted two instrumented exams to aid in the diagnosis of a vestibular disorder. The first test was the instrumented Timed Up and Go test (iTUG), which measures postural transitions and gait as the subject moves from seated, to standing, to walking. The second test was the instrumented postural sway test (iSway), which measures the amount of side-to-side movement a person exhibits when standing still.

Additionally, both the participants and the operators were given a questionnaire meant to assess ease of use of the measurement tools. The question was a simple scale from 1 to 4, with 1 being “easy” and 4 being “not possible to use.” The operators were also asked to track how long the entire testing process took from start to finish.

Methods

All participants completed a total of 12 tests. For the first round of testing, three iTUG tests and three iSway tests were completed on the same day. A week later, this process was repeated. The repetition was meant to test the reliability of the tools.

For both tests, participants’ movements were tracked with Opal wearable sensors. The sensors were attached with Velcro straps to the participants’ wrists, chest, sternum and lower legs. They sent synchronized, real-time data to a computer for automated analysis.

During the iTUG test, participants began by sitting in a chair. They were instructed to get out of the chair without pushing off with their arms, walk seven meters to a piece of tape that had been placed on the ground, turn 180 degrees, walk back and sit back down in the chair.

During the iSway test, participants stood up straight with a wooden wedge between their feet and their arms crossed over their chest. They were instructed to fix their gaze on a steady target for 30 seconds.

In addition to the physical tests, participants provided a history of falls in the previous year. Participants and operators were also asked to rank how easy or difficult the tests were to administer and complete.

Findings

Overall, the researchers were looking for evidence of feasibility, reliability and ability to classify fallers using the parameters of the iTUG and iSway tests and the Opal wearable sensors.

First, they found that this method of testing was indeed feasible in a clinical setting. Everyone gave the tools a ranking of 1, meaning they were easy to use. Furthermore, the process was very quick, with set up taking five minutes, testing taking 10 minutes and downloading data taking just two minutes. This speediness is invaluable in a clinical setting, as it could cut healthcare costs and help medical professionals treat more patients.

Second, they found that wearable sensors have great potential for objective testing and that many of the outcome measures had good or excellent test-retest reliability. Out of 32 iTUG parameters, 9 were excellent and 16 were good. Out of 47 iSway parameters, 27 were excellent and 15 were good.

Lastly, the researchers concluded that there is potential for wearable sensors to help classify fallers and non-fallers. In this research study, only one of the “excellent” parameters from the iSway test had any correlation with falling data. However, the classifier was 66.67 percent accurate overall with this information. In a larger study, the researchers expect to see more parameters that meet the standard for reliability, and thus, a more nuanced and accurate classification system.

Help Vestibular Patients with APDM Wearable Technologies

APDM Wearable Technologies is a digital health company focused on discovering reliable and sensitive outcome measures of disease progression. Originally founded to help patients with Parkinson’s disease, the Opal wearable sensors and Mobility Lab software have become standard use in a variety of settings. APDM provides actionable outcomes measures for patients with neurological and chronic diseases causing functional mobility issues, including vestibular disorders.

If you are looking for a portable, sensitive and reliable system to test your patients’ mobility, please contact us online today. Also make sure to stop by our booth if you will be attending the upcoming APTA Combined Sections Meeting in New Orleans this February 21 – 24, 2018.

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