Dr. Jiwon Oh – a rising star in the field of multiple sclerosis – appears relaxed as she stands in front of a group of fellow neurologists, MS patients and interested donors. They are here to learn about her latest research.
And yet she is about to tell them about a troubling contradiction. It’s about a group of unusual patients whose MRIs show the telltale signs of multiple sclerosis – lesions on the brain and spine – but who have no symptoms suggestive of the disease.
On the one hand, these patients may hold the key to understanding a disease that has stymied researchers for decades. On the other hand, Dr. Oh must advise them about how to treat something that might or might not develop into MS.
It’s only in the past few decades that this unexpected group of people has come to light. As MRIs have become more common, doctors have been ordering scans for patients who have family histories of aneurysms, or suffer from headaches, or have been in car accidents.
A small number of these patients have shown lesions, but strangely, they have healthy motor, sensory and general neurological function.
For the past two years, Dr. Oh and her colleagues have been recruiting these patients for studies. They have signed up 50 so far – one of the largest groups in a single centre anywhere in the world.
Researchers call this condition radiologically isolated syndrome (RIS) and are just beginning to study it. Their goal is to get to the bottom of the medical anomaly with the help of more advanced imaging technology.
“A bright spot on the MRI indicates a lesion, but we don’t actually know what the specific damage is to neural tissue,” says Dr. Oh.
Which leads to Dr. Oh’s dilemma as a doctor. Only a portion of these patients will go on to develop MS. Still, the earlier people with MS receive treatment, the better their prognosis will be.
As she puts it, “it’s really difficult to convince someone who is feeling well to start on a treatment that may involve injecting themselves every day or taking a pill, with lots of side effects. It’s an uncomfortable position to be in.”
One recent study that collected data from over 20 centers around the world found that one-third of those with RIS went on to develop MS within five years. While all had lesions on the brain, not all had them on the spinal cord. But those who did were most at risk of developing the disease.
That’s where Dr. Oh enters the picture. She is one of a handful of researchers in the world who uses advanced imaging technology – including diffusion tensor imaging, magnetization transfer imaging and functional MRI – to explore the impact of MS on spinal cord tissue. These technologies give better insight into the type of tissue damage involved.
When Dr. Oh and her team compared spinal cord scans of 24 RIS patients and 14 healthy people, they unexpectedly discovered that a much larger proportion of RIS subjects had spinal cord lesions than previously reported: 70 per cent of those with RIS had spinal cord lesions.
When they probed further, they discovered something surprising: while the spinal tissue was inflamed and there was damage to the protective covering of the nerve fibers, the spinal tissue was still relatively intact at the microstructural level.
That there was no substantial microstructural damage may be key. That’s because typical MS patients do show this kind of damage.
Dr. Oh and her team are now trying to determine if this anomaly is significant and why some RIS patients eventually go on to develop MS – while others don’t. It may be that the timing and extent of damage to the spinal cord is the key to unlocking the mystery behind what “triggers” some RIS patients to develop MS.
“RIS patients may represent the very earliest detectible stage of MS so they’re very, very important to study,” says Dr. Oh. “We need to keep following them to find out what triggers the actual symptoms.”