October 9, 2013
Trans-Cranial Magnetic Stimulation Could Help Treat Chronic Dizziness
redOrbit Staff & Wire Reports - Your Universe Online
Researchers from the Johns Hopkins University School of Medicine believe that they have located a specific site in the human brain that could be one of the sources of dizziness and spatial disorientation.While dizziness can also be linked to damage to the inner ear, or to other senses such as vision, neurology instructor Dr. Amir Kheradmand and his colleagues report that they have discovered a region of the brain that plays a vital role in our subconscious awareness of which way is up and which way is down.
Their study, which appears online in the journal Cerebral Cortex, claims that some causes of dizziness, unsteadiness and “floating” could be linked to that region in the parietal cortex.
The processes in that area, which translate input from the inner ears regarding the pull of gravity and the eyes regarding our visual sensation about upright perception, can become disrupted, the study authors explain. Even then, the brain is automatically able to recognize which way is actually “up” and which way is “down”.
“Our brain has this amazing way of knowing where we are in space, whether we are upright or tilted at an angle, even if it is completely dark and we can't see anything around us,” Dr. Kheradmand explained in a statement. “This study suggests there's a small area of neural tissue in the parietal cortex substantially involved in this ability, giving us a place to start thinking about how we may be able to treat people with disorienting dizziness.”
The study authors opted to focus their analysis on the right parietal cortex, as research on stroke victims with balance problems has suggested that damage to that region of the brain was directly involved with upright perception.
They recruited eight healthy subjects, placing each in a dark room and showing them lines that were illuminated on a screen. Dr. Kheradmand’s team then had the study participants report the orientation of each line by rotating a dial to the left, the right, or straight ahead.
The subjects then received trans-cranial magnetic stimulation (TMS) – an FDA-approved treatment for depression and which “painlessly and noninvasively delivers electromagnetic currents to precise locations in the brain that can temporarily disrupt the function of the targeted area,” according to the university.
Each individual had an electromagnetic coil placed behind the ear and against the scalp in a 2-centimeter wide location across the right parietal lobe, a location that had originally been discovered through the mapping of a small cortical region parietal lobe in one of the subjects.
The subjects received 600 electromagnetic pulses over the course of 40 seconds, and at the end of each session, they were asked a second time to show the researchers which way the illuminated line was positioned. At the end of the study, all of the subjects reported that his or her sense of being upright had been altered in the same way after TMS was administered in the same location in the parietal cortex: the supramarginal gyrus.
According to Kheradmand, his team’s findings suggest that this form of stimulation could be used to treat chronic dizziness. “If we can disrupt upright perception in healthy people using TMS, it might also be possible to use TMS to fix dysfunction in the same location in people with dizziness and spatial disorientation,” he said.
“It's fascinating that we've gotten to the point that we can show that a subconscious perception can be altered using this simple, noninvasive technique,” the professor added. “We're excited that this could someday be a key to helping people who have dizziness and spatial disorientation to feel better.”