An iPhone and a bucket help diagnose vestibular problems in dizzy children

dizziness vestibular bucket testDizziness is fairly common in children, but it can be very hard to diagnose the cause. Any number of conditions can produce dizziness, and children are a special challenge since they often can’t describe what they’re feeling.

“One of the toughest things to figure out is, is it a problem with the vestibular system, or is it part of something else, a heart problem or an eye problem?” says Jacob Brodsky, MD, director of the Balance and Vestibular Program at Boston Children’s Hospital. “Then, the next challenging part is determining whether it is an inner ear problem or a central vestibular disorder — a problem with the brain.”

A definitive answer often requires a battery of tests that few providers outside Boston Children’s can perform in children, as they require sophisticated and expensive equipment. But with an ordinary bucket, an iPhone, an $18 app and some Velcro, Brodsky can quickly get a good indication of whether a child has a vestibular problem—and specifically an inner ear problem.

A poor man’s vestibular test

In the current state-of-the-art test, called the “subjective visual vertical,” or SVV, the patient is placed in a darkened room, shown a slightly off-kilter vertical line projected on a screen and asked to adjust the line with a remote until it appears precisely vertical.

“We can then measure how many degrees this differs from the true vertical,” explains Brodsky. This helps confirm that the dizziness is coming from a peripheral vestibular problem — vestibular loss in the inner ear rather than a brain problem.

Bucket with iPhoneAn Australian clinician, Matthew Holmes, realized you could reproduce this test much more cheaply, with an iPhone app that displays the same vertical line. The phone is adhered to the bottom of a bucket. Patients put their heads inside, to block any outside visual orientation cues, then rotate the bucket to “straighten” the line. A GPS-type system in the app calculates the deviation from true vertical.

Brodsky happened to see Holmes’ solution online and discussed it with some of his colleagues. “We decided to take it upon ourselves to validate it,” he says.

In a study recently published in the International Journal of Pediatric Otorhinolaryngology, Brodsky and colleagues had 39 children (7 to 18 years old) with varying causes of dizziness take the iPhone bucket test. They gave children three tries to straighten the line, and took the average of the results.

Staffer with bucket SVVWhen the cutoff was set at 2.1 degrees of deviation from true vertical, the test accurately identified all six children with peripheral (inner ear) vestibular loss, performing as well as conventional testing. “That degree of tilt is an indicator that the utricle in the inner ear, which senses linear movement, is not working normally,” Brodsky explains.

In contrast, children with other forms of dizziness (benign positional vertigo, central vertigo and other causes like thyroid or heart conditions) all passed the iPhone bucket test, as did children without dizziness.

An earlier bucket test, described in 2009, used a hanging pendulum and a protractor to measure the deviation. But it was cumbersome to set up and didn’t catch on. Since the iPhone app is easy to use, Brodsky hopes to see it adopted by pediatricians, neurologists and otolaryngologists.

“One of our goals is to try to give more opportunities for physicians in the community to be able to test for vestibular problems more easily in the office,” he says.

Other pediatric vestibular programs have begun evaluating different uses for the app, such as testing for peripheral vestibular loss in children with concussion.

Holmes’ company, Clear Health Media, has a video on its website that describes how to implement the app. “With its low price, we aren’t able to spend a lot on advertising it, so people mainly find it through word of mouth or on Google,” Holmes says.

Source: Brodsky J; et al. Peripheral vestibular loss detected in pediatric patients using a smartphone-based test of the subjective visual vertical. Int J Pediatr Otorhinolaryngol 2015, http://dx.doi.org/10.1016/j.ijporl.2015.09.020