Researchers at Johns Hopkins University School of Medicine in Baltimore have proposed that the strong pull of an MRI’s magnetic field could potentially be used to diagnose, treat and study inner ear disorders that lead to balance disorders or dizziness.
Videos of patient eye movements while in an MRI machine, observed without taking any MRI images, revealed characteristic eye movements in patients with such inner ear problems, according to the results of a study published online March 13 in Frontiers in Neurology.
For the study, Bryan Ward, MD, and colleagues at Johns Hopkins placed nine patients with balance problems in a 7T MRI machine. Previous research had already shown that an MRI’s magnetic field push on the inner ear fluid in the semicircular canals, which are responsible for maintaining balance. When in such a strong field, an individual’s eyes to repeatedly drift to one side and then jerk back, distinctive movements called nystagmus. The researchers wanted to see if these eye movements looked different in patients with balance disorders.
Ward and colleagues found that people with inner ear problems on one side displayed eye movements dependent on which ear was affected. The eyes of patients with left ear disorder had eyes that drifted down before jerking up, while those patients whose right ear was affected had the reverse eye movements. Healthy patients did not show the same patterns of nystagmus as those with inner ear disorders.
If confirmed, this method could replace uncomfortable exams currently used to determine whether a patient’s dizziness or imbalance is originating in the inner ear, which could involve uncomfortable ear canal irrigation.
"Our results further suggest a use for [magnetic vestibular stimulation] in evaluating the function of individual labyrinthine structures as well as a novel and comfortable way to induce a sustained nystagmus in normal subjects and study the response of adaptive mechanisms to a pathological vestibular imbalance,” wrote the authors.