Dizziness a puzzler
Dizziness associated with mal de débarquement syndrome puzzles experts
In 2007, a few days after participating in a two-day sailing race, Cathy Helowicz began feeling dizzy. It was as if the floor and walls were moving. A decade later, “it’s never gone away,” she says. “Sometimes I wake up at 4 a.m. and feel like I’m in a washing machine.”
Helowicz, 57, a former government computer scientist, suffers from mal de débarquement syndrome (MdDS), a puzzling neurological disorder that leaves patients feeling as if they are rocking, swaying or bobbing when they are actually still.
“I was very fortunate I didn’t have to go to a job, since you really cannot work with this,” she says of the little-understood disorder. (Helowicz left the government when she was 34 — before developing MdDS — and now writes children’s books and spy novels.) “I went through 11 doctors, 13 medications and seven months before I found a doctor who said I had classic MdDS symptoms.”
Onset typically follows motion exposure — after a cruise, for example, or after flying, riding a train, even a lengthy car ride. MdDS can last for months, even years. It also can occur spontaneously, without motion exposure, although that is less common.
“It’s an oscillating feeling like walking on a suspension bridge or a trampoline,” says Yoon-Hee Cha, an assistant professor at the Laureate Institute for Brain Research in Tulsa, Okla., who has been studying MdDS. “It can be an absolutely devastating disorder. What is difficult for people to understand is that patients can look normal but feel awful.”
It’s unclear how many people have it, although it seems to predominantly affect women, according to the MdDS Balance Disorder Foundation. It probably is underreported, the group says.
Its cause also is unknown. The foundation says experts believe it probably is a form of motion sickness related to a malfunction in the vestibular-ocular reflex (VOR), a mechanism in the inner ear that maintains balance and stabilizes the eyes during head movements. When at sea, for example, the VOR adapts to motion; in people with MdDS, this reflex does not readjust on dry land.
Classic motion sickness, however, occurs during the actual motion experience, usually with nausea. “MdDS happens after you get off the vehicle, typically without nausea,” Cha says.
Cha said she thinks the brain experiences a breakdown in its ability to process sensory information. When the brain processes predictable stimuli, we respond without consciously thinking about it, she said.
“When we walk, we have a pattern and we create a model for the sensations that we should expect when we walk,” she says. “We can ignore those sensations of our feet hitting the ground. In people with MdDS, that prediction machinery is off because they always feel like they are moving. They have a problem updating new sensory information.”
Mingjia Dai, an assistant professor of neurology at the Icahn School of Medicine at Mount Sinai in New York, has developed a promising treatment for MdDS that involves exposing patients to visual cues and motion patterns that are opposite those they usually experience. The idea is much like straightening the path of a veering car by turning the steering wheel back toward the centre of the road.
“The reason they have this disease is because their vestibularocular reflex is maladapted, and the treatment re-adopts them,” Dai says.
While slowly rolling their heads from side to side, patients watch a moving pattern of black-and-white stripes projected on the wall of a small circular room. The direction of the stripes’ motion and speed of the head movements are individually tailored for each patient based on what that patient experiences with MdDS.
Dai and his colleagues have treated about 380 people. In their first small study, which involved 21 women and three men, 17 recovered completely or improved substantially. Six responded well initially, but their symptoms returned. One did not improve at all. A followup study of 141 patients one year after their treatment found that roughly half of them still were doing well. These studies did not have control groups for comparison purposes; the researchers are planning future studies, including one with controls.
Cha’s research is focused on the neurological basis of MdDS. She is using several tools, among them non-invasive brain stimulation, functional MRI (which measures brain activity by detecting changes associated with blood flow), PET (positron emission tomography) and EEG (electroencephalogram).
Transcranial magnetic stimulation, one form of brain stimulation under study, sends a magnetic field through the skull to create a current on the surface of the brain.
“We have tried different brain targets and patterns of stimulation,” she says. “We’ve seen improvement rates ... (and) we’re trying to figure out what network (in the brain) got them better. We want to understand what’s going on in the brain” that isn’t picked up by standard diagnostic tests.”
In addition to feelings of uncontrollable movement, MdDS patients also often experience anxiety, fatigue, difficulty maintaining balance, unsteadiness and difficulty concentrating. Stress and other triggers, such as exposure to noise or bright lights, can worsen symptoms. Helowicz takes medication usually prescribed for seizures and panic disorders, which helps. “Before I started taking the medication, I would walk the streets at night because I couldn’t sit still,” she says.
Oddly, patients often do feel better when they are moving, a quirk that helps diagnose the disorder. “If that rocking feeling gets better when you are driving a car or back on the boat, it’s never anything else but MdDS,” Cha says.
MdDS sometimes disappears on its own, but it can come back. “However, if the symptoms last about six months, the chances of an eventual remission becomes lower and lower,” Cha says.
This is what happened to Helowicz. She had her first bout with MdDS in 1999, after a cruise. It resolved after a month but returned eight years later. “In 2007, for whatever reason, it didn’t go away,” she says. “It was like something just snapped and never reset.”