Winnie Chu, MB ChB, FRCR, FHKCR, FHKAM (Radiology), a professor in the Department of Imaging & Interventional Radiology at The Chinese University of Hong Kong (CUHK), China, has uncovered a previously unknown relationship between the inner ear, the brain, and the spinal column that causes previously healthy girls to suddenly begin to develop an abnormality in the shape of the spine.
Previous medical theory suggested that scoliosis only affected the spine and the vertebrae that make it up. But Chu has found that the condition also involves anomalies in the brain and the semicircular canals of the ear, as well as the spinal cord inside the spine, according to a CUHK press release.
Chu was initially studying the lung function of patients with scoliosis and how the spine affects lung performance, but became interested in the theory surrounding the cause of scoliosis, and began examining the spinal cord itself, as well as the brain, and then the systems of the ear. By studying the parts of the brain that determine how the body balances itself, she said she realized patients with scoliosis had an asymmetry in those systems that potentially throws them off balance.
Such a relationship had been posited in academic papers and conferences, although it had yet to be confirmed clinically. “I listened to the discussion, and I thought it sounds reasonable,” Chu said. X-ray technology has yielded images of the spinal structure for more than a century, but it examined just the bones and the shape of the spine. It’s only through advances in magnetic resonance imaging (MRI) that it has become possible to scan the activity of the nervous system and spinal column in any great detail. Chu has now developed a large database of MRI information from her clinical practice treating patients with scoliosis at Prince of Wales Hospital, Hong Kong.
It was also previously difficult to study the vestibular system, the inner ear, in any great detail. Whereas the spinal column and brain develop extensively after we are born, the vestibular system changes very little after birth.
Chu said she now believes that it is likely scoliosis begins with an imbalance in the inner ear, which governs how we keep our balance. In scoliosis patients, the inner ear rotates on slightly different axes from normal, and the shape of the inner ear is different. That results in the system not being as effective as normal, resulting in a slight loss of balance, Chu’s work shows. With the body not in its correct posture, the imbalance may eventually lead to curvature of the spine.
The cause of scoliosis remains largely unknown, although it has been suggested that there’s a genetic component. It’s also possible that, since girls are more slender and often taller than boys in adolescence, it is a byproduct of growth spurts that leave the body unable to handle the rapid growth of the spine, the CUHK press release said.
If Chu’s theory about the effect of the inner ear proves correct, it’s possible that training the patient to strengthen his or her balance could prevent scoliosis, or curb its severity. An improved understanding of the origin of the disease could also lead to better screening to identify at-risk children, and the chances of how severe the condition will be.
“There are still a lot of things to explore,” Chu said.
