Institute for Neuromusculoskeletal Research, OU-HCOM awarded grant for research on rare balance disorder

Mal de Debarquement (French for “disembarkation sickness”) is a false but persistent sensation of motion, such as rocking, swaying, tumbling or bobbing that usually develops after a cruise, aircraft flight, train or car travel. The most common symptoms of MdDS include dizziness, unsteadiness, fatigue, confusion, visual disturbances, difficulty concentrating and anxiety. Being in an enclosed space or attempting to be motionless, such as sitting, lying down or standing in a stationary position, often increases symptoms. Symptoms tend to decrease when the person is in a moving car, airplane or train.

According to Dr. Clark, there is no definitive diagnostic test for MdDS. “It’s a diagnosis of exclusion, meaning it’s only diagnosed after all the basic tests, such as blood work, MRI and inner ear exams are conducted and nothing is found,” he explained.

As such, he noted, MdDS may be under-diagnosed. “There are currently no treatment options for MdDS, and the condition can range from mild to totally disabling,”

Dr. Clark and his collaborator Adam Quick, M.D. (Department of Neurology at The Ohio State University) recently published their case study findings on a patient with MdDS in the Journal of Neurology, and the upcoming study, titled “Role of Intracortical Excitability in Mal de Debarquement Syndrome,” will expand on these preliminary findings by measuring brain excitability in MdDS patients using sophisticated neurophysiologic techniques, including transcranial magnetic stimulation (TMS).

According to Dr. Clark, TMS is a safe and non-invasive technique. “It’s a simple, painless procedure, and the person is totally alert the entire time,” he explained. “First, we place electrodes on the muscles of the person’s forearm. We then introduce a very brief, rapidly changing magnetic field over their head. This causes brain neurons to fire and transmit signals to motor neurons. The result is a slight contraction in the person’s forearm muscles.”

A combination of single and double pulses is administered to the subject’s brain at different intervals and under different conditions, such as having the individual open or close their eyes and having them rest or contract their forearm muscles. 

Based on the magnitude of the electrical signals, researchers can assess the excitability of a subject’s motor cortex. The brain’s motor cortex deals with the planning, controlling, and execution of voluntary motor functions, such as lifting an object or climbing a flight of stairs.  “This will help us understand the neuronal connections in the brain as well as its plasticity, which refers to the brain’s ability to change as a result of one's experience,” Dr. Clark explained. “The information is important because it will help us identify what’s different about the nervous system of people with MdDS.”

Dr. Clark will also work closely with Thad Wilson, Ph.D. in the Department of Biomedical Sciences at Ohio University to also look at the ability of the autonomic nervous system – which controls and modulates many involuntary reflexes, such as heart rate and blood pressure – to adjust to certain environmental conditions.

“We’ll measure the beat–to-beat variability in heart rate and blood pressure and examine how this changes in response to certain tasks, such as moving someone’s head in a certain direction or having them go from lying down to an upright posture very rapidly,” he explained. 

The study will enlist 24 participants who’ll receive $150 each. Half of the participants must have been diagnosed with MdDS and the other 12 must be free of the disease but be the same gender and age as those with the disorder. It is expected that the majority of patients with MdDS will be travelling to Ohio University from all over the United States to participate in the study.  Research is expected to begin in early January, with all data collected within six months, and the study completed within a year.

According to Dr. Clark, the research is clinically significant because it will be one of the first experiments to explore the pathophysiology, or changes in normal brain function, associated with MdDS. “Our findings will provide a better understanding of this devastating and poorly understood balance disorder,” he notes. “Hopefully, it can lead to developing techniques and criteria for diagnosis as well as treatment strategies.”

If you are interested in participating in this study, either as a patient with MdDS or as a control subject, contact Clark at clarkb2@ohio.edu for more information.