Multiple sclerosis (MS) is a potentially disabling disease of the brain and spinal cord.  It is an auto-immune disease, where the immune system turns on itself and attacks the nerve cells, damaging the protective sheath. This process is called demyelination and it disrupts  ‘messages’ transmitted from and to the brain, slowing, distorting or blocking them.  Eventually, the disease can cause permanent damage or deterioration of the nerves.

Signs and symptoms of MS vary widely and depend on the amount of nerve damage and which nerves are affected. Some people with severe MS may lose the ability to walk independently or at all, while others may experience long periods of remission without any new symptoms. There's no cure but treatments can speed recovery from attacks, modify the course of the disease and manage symptoms.

Additional symptoms can include;

• Numbness or weakness in one or more limbs that typically occurs on one side of the body at a time.
• Electric -shock sensations with certain neck movements, especially bending the neck forward. (l'hermitte sign).
• Tremor, lack of coordination or unsteady gait.
• Partial or complete loss of vision, usually in one eye at a time, often with pain during eye movement or prolonged double or blurry vision.
• Slurred speech.
• Fatigue.
• Dizziness.
• Problems with bladder or bowel function.

Most people with MS have a relapsing-remitting disease course. They experience periods of new symptoms or relapses that develop over days or weeks and usually improve partially or completely. These relapses are followed by quiet periods of disease remission that can last months or even years.

Small increases in body temperature can temporarily worsen signs and symptoms of MS, but these aren't considered true disease relapses. At least 50% of those with relapsing-remitting MS eventually develop a steady progression of symptoms, with or without periods of remission, within 10 to 20 years from disease onset. This is known as secondary-progressive MS.

The worsening of symptoms usually includes problems with mobility and gait. The rate of disease progression varies greatly among people with secondary-progressive MS.  Some people with MS experience a gradual onset and steady progression of signs and symptoms without any relapses, known as primary progressive MS.