Two new studies suggest that magnetic fields from MRI scanners could be used to diagnose, treat, and study inner-ear disorders in the future, replacing more invasive and uncomfortable examinations.
In one study, researchers at Johns Hopkins University (JHU) School of Medicine found that people with balance disorders or dizziness due to an inner-ear disturbance showed distinctive abnormal eye movements when the affected ear was exposed to the pull of a magnetic field (Frontiers in Neurology, March 13, 2014).
Dr. Bryan Ward, a resident in JHU's department of otolaryngology-head and neck surgery, and colleagues placed nine patients with balance problems in an MRI scanner and recorded their eye movements using video, without acquiring any MR images.
Earlier research from the group had shown that healthy volunteers subjected to a 7-tesla magnetic field experienced a characteristic eye movement called nystagmus, in which the eyes repeatedly drift to one side and then jerk back. The eyes of healthy volunteers moved side to side when they were in the scanner, with the direction of movement dependent on whether they entered the MRI tunnel head or feet first. However, in the current study, those with inner-ear problems displayed different movements that depended on which ear was affected.
In the second study, Ward and colleagues investigated whether the inner-ear balance systems of zebra fish are influenced by magnetic stimulation. Zebra fish are a popular model for genetics and pharmaceutical studies of hearing and balance because of the group's anatomical similarity to humans' vestibular systems (PLOS One, March 19, 2014).
The researchers placed 30 healthy zebra fish, one at a time, into an 11.7-tesla magnetic field, using a smaller MRI machine to better accommodate the aquarium used to hold each fish.
When the aquarium was in the magnetic field, the majority of fish responded in a way akin to the vertigo and imbalance that humans with inner-ear system disturbances show -- the fish flipped, rolled, and swam faster than normal. The fish reverted to normal swimming behavior only when their aquarium was taken away from the magnet.
