Featured Research

from universities, journals, and other organizations

Researchers pinpoint the cause of MRI vertigo: Machine's magnetic field pushes fluid in the inner ear's balance organ

Date:
September 23, 2011
Source:
Johns Hopkins Medical Institutions
Summary:
A team of researchers says it has discovered why so many people undergoing magnetic resonance imaging (MRI), especially in newer high-strength machines, get vertigo, or the dizzy sensation of free-falling, while inside or when coming out of the tunnel-like machine.

A team of researchers says it has discovered why so many people undergoing magnetic resonance imaging (MRI), especially in newer high-strength machines, get vertigo, or the dizzy sensation of free-falling, while inside or when coming out of the tunnel-like machine.

In a new study published in Current Biology online on Sept. 22, a team led by Johns Hopkins scientists suggests that MRI's strong magnet pushes on fluid that circulates in the inner ear's balance center, leading to a feeling of unexpected or unsteady movement. The finding could also call into question results of so-called functional MRI studies designed to detect what the brain and mind are doing under various circumstances.

To determine the mechanism behind MRI-induced vertigo, Dale C. Roberts, M.S., senior research systems engineer in the laboratory of David Zee, M.D., within the Department of Neurology at the Johns Hopkins University School of Medicine, and his colleagues placed 10 volunteers with healthy labyrinths (inner tube-like structures in the ears that control balance) and two volunteers who lacked labyrinthine function into MRI scanners. They tracked vertigo not only by the volunteers' reports, but also by looking for nystagmus, a type of involuntary eye movement that reflects the brain's detection of motion -- the kind of jerky eye tracking that a person on a merry-go-round might experience. Because visual clues can help suppress nystagmus, the researchers conducted their experiments in the dark.

Footage from night vision cameras showed that all the healthy volunteers had nystagmus in the MRI, but those without labyrinthine function didn't -- a sure sign that the labyrinth plays a key role in MRI-related vertigo.

To figure out how MRI's magnetic field acts on the labyrinth, the researchers tested the healthy volunteers in MRIs of different strengths for various periods of time. They also tracked the volunteers' nystagmus as they were moved in and out of the machines' tunnels, called bores, both from the usual entryway and from behind -- experiments designed to test the impact of motion or direction of magnetic field on the volunteers' balance centers.

Roberts' team found that higher magnetic field strengths caused significantly faster nystagmus. These eye movements persisted throughout the time volunteers spent in the machine, no matter how long the experiments lasted. In addition, the direction of the eye movements changed depending on which way the volunteers entered the bores, suggesting that the effect on the labyrinth was directionally sensitive.

Combining their results with what's known about the inner ear, the researchers surmised that MRI-related vertigo most likely relates to interplay between electrical currents flowing through the salty fluid in the canals of the labyrinth and MRI's magnetic field.

Through an effect well known to physicists called the Lorentz force, the magnetic field apparently pushes on the current of charged particles in the inner ear's fluid. This exerts a force on cells that use the fluid's flow as a way to sense motion.

Roberts notes the finding not only solves a decades-long scientific question, but also has implications for research that uses MRI. In one technique, known as functional MRI, researchers measure brain activity by tracking blood flow in the brain as subjects perform tasks. The new findings suggest that the scanner itself could be causing previously unnoticed brain activity related to movement and balance, potentially affecting results.

"We've shown that even when you think there's nothing happening in the brain while volunteers are in the scanner, there's actually a lot happening because MRI itself is causing some effect," Roberts says. "These effects must be taken into account in the way we interpret functional imaging."

The researchers add that doctors already use methods that stimulate the labyrinth to diagnose and treat inner ear and balance disorders, but these methods can be uncomfortable. They note that MRI's strong magnetic field could eventually be used for the same purpose, providing a novel method that's more comfortable and noninvasive.

Other researchers who participated in this study include Joseph S. Gillen, B.S., John P. Carey, M.D., Charles C. Della Santina, Ph.D., M.D., and David Zee, M.D., all of Johns Hopkins; and Vincenzo Marcelli, M.D., of Federico II University of Naples.

The study was supported by a grant from the Johns Hopkins Brain Science Institute and gifts from grateful patients.


Story Source:

The above story is based on materials provided by Johns Hopkins Medical Institutions. Note: Materials may be edited for content and length.


Journal Reference:

  1. Dale C. Roberts, Vincenzo Marcelli, Joseph S. Gillen, John P. Carey, Charles C. Della Santina, and David S. Zee. MRI Magnetic Field Stimulates Rotational Sensors of the Brain. Current Biology, 2011; DOI: 10.1016/j.cub.2011.08.029

Cite This Page:

Johns Hopkins Medical Institutions. "Researchers pinpoint the cause of MRI vertigo: Machine's magnetic field pushes fluid in the inner ear's balance organ." ScienceDaily. ScienceDaily, 23 September 2011. <www.sciencedaily.com/releases/2011/09/110922134529.htm>.
Johns Hopkins Medical Institutions. (2011, September 23). Researchers pinpoint the cause of MRI vertigo: Machine's magnetic field pushes fluid in the inner ear's balance organ. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2011/09/110922134529.htm
Johns Hopkins Medical Institutions. "Researchers pinpoint the cause of MRI vertigo: Machine's magnetic field pushes fluid in the inner ear's balance organ." ScienceDaily. www.sciencedaily.com/releases/2011/09/110922134529.htm (accessed April 18, 2014).

Share This



More Health & Medicine News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Obama: 8 Million Healthcare Signups

Obama: 8 Million Healthcare Signups

AP (Apr. 17, 2014) President Barack Obama gave a briefing Thursday announcing 8 million people have signed up under the Affordable Care Act. He blasted continued Republican efforts to repeal the law. (April 17) Video provided by AP
Powered by NewsLook.com
Is Apathy A Sign Of A Shrinking Brain?

Is Apathy A Sign Of A Shrinking Brain?

Newsy (Apr. 17, 2014) A recent study links apathetic feelings to a smaller brain. Researchers say the results indicate a need for apathy screening for at-risk seniors. Video provided by Newsy
Powered by NewsLook.com
Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
Powered by NewsLook.com
Thousands Of Vials Of SARS Virus Go Missing

Thousands Of Vials Of SARS Virus Go Missing

Newsy (Apr. 16, 2014) A research institute in Paris somehow misplaced more than 2,000 vials of the deadly SARS virus. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins