Multiple Sclerosis

Multiple sclerosis is a condition in which the immune system attacks myelin, the insulating coating around nerve fibres in the brain, the spinal cord and the optic nerves. Myelin is what lets a signal travel fast and cleanly; where it is stripped away the signal slows, distorts or fails, and what you notice depends entirely on which pathway was affected.

Most people start with a relapsing course. An episode develops over days, lasts weeks, then settles partly or completely, with stable periods in between that can run for years. After a decade or two some people move into a phase of slow progression without distinct episodes, and a smaller group is progressive from the outset.

The cause is not fully known and is best understood as a genetic susceptibility that something in the environment acts upon. Low vitamin D, previous infection with the Epstein-Barr virus and smoking are the associations that keep appearing. It is not inherited in any simple way, a child of a parent with MS is very unlikely to develop it, and it cannot be caught from anyone. It is diagnosed most often between twenty and forty and more often in women.

The diagnosis rests on showing damage separated in space and in time: more than one area of the nervous system involved, on more than one occasion. Your neurologist starts with the history, and that includes episodes you may have dismissed years ago, such as a few weeks of blurred or washed-out vision in one eye, numbness in a band around the trunk, or a limb that went clumsy for a month and then recovered.

The examination sweeps the whole nervous system. Eye movements, colour vision and the optic discs, power, tone, reflexes, coordination, sensation in the limbs and trunk, and the way you walk. It frequently finds signs of old damage you never knew about, and those signs are part of the evidence.

An MRI of the brain and spinal cord is central, and it is read for the number, position and age of the areas involved. A sample of the fluid around the spinal cord is taken in some cases, and blood tests exclude the conditions that imitate MS, which is an important step because several are treated in ways that would be wrong here. A single episode with a characteristic scan is now sometimes enough to make the diagnosis, and that matters, since treatment started early does more good than the same treatment started late.

A relapse builds over days, plateaus, then improves over weeks to months. A short course of steroids speeds up the recovery of a disabling relapse by days to weeks and does not change where you eventually end up, so they are used for relapses that affect function and left alone for mild ones. Recovery continues quietly for six to twelve months after an episode, so judgements about permanent loss are best not made at three months.

Long-term treatment aims at preventing the next relapse and at slowing the accumulation of damage, and it is judged over years, using relapses and repeat scans together. It is taken continuously, including through the stable stretches when nothing seems to be happening, because the stable stretches are the point of it.

Fatigue is what most people find hardest and it responds to pacing, to treating disturbed sleep, to graded exercise, which improves it in the long run, and to managing heat, since a rise in body temperature temporarily worsens symptoms and everything returns once you cool down. Physiotherapy works best as a continuing habit and not as a course of six sessions.