Multiple sclerosis (MS) is a lifelong condition affecting the brain and nerves, and there are a number of warning signs to look out for.
Inflammation can occur in parts of the brain or spinal cord which causes symptoms and it is estimated around 130,000 people in the UK live with the condition.
Affected nerve fibres can become vulnerable to damage, and over time may be lost entirely. When this happens, messages can no longer get through and symptoms become permanent.
This gradual, steady accumulation of disability is called MS progression
The NHS says MS can cause a wide range of potential symptoms, including problems with vision, arm or leg movement, sensation or balance.
Below are some of those to look out for in yourself or loved ones.
Vision Problems
One of the more obvious first signs of MS is a problem with vision , known as optic neuritis which is where swelling damages the optic nerve.
Common signs of optic neuritis include pain with eye movement and temporary loss of vision in one eye.
Optic neuritis is considered a more 'concrete symptom', as others - such as numbness and tingling - are often vague and can be attributed to a number of other causes.
Fatigue
Every one of us gets tired but MS fatigue is very different as people describe it as an overwhelming sense of tiredness with no obvious cause.
The MS Society says warning signs to watch for include feeling extremely tired after very little activity, waking up feeling as tired as you did when you went to sleep andlimbs feeling heavy.
Numbness and tingling
The NHS says abnormal sensations can be a common initial symptom of MS. And this can often take the form of numbness or tingling in different parts of your body, such as the arms, legs or trunk, which typically spreads out over a few days.
The MS Society says a common type of discomfort in MS is unpleasant, unusual sensations that appear to be in your skin, such as numbness and tingling, which is caused by damage to nerves.
Loss of balance and dizziness
Feeling dizzy is a common symptom of MS, as is feeling 'off balance' or lightheaded. Far less often experienced is vertigo, which is the sensation that a person - or their surroundings - are spinning.
Stiffness or spasms
Muscle stiffness and spasms are common MS symptoms, and are often described as 'spasticity'.
These symptoms can affect between 40 per cent and 80 per cent of people with MS at some time.
For most people, the stiffness and spasms come and go.
Tremors
A tremor is a neurological disorder that causes shaking movements in one or more parts of your body, most often in your hands, says the National Institutes of Health. This can be mild or more pronounced, for example enough to spill a cup of drink if it's full or affecting handwriting.
Pain
Pain in MS can take on many different guises and be caused by direct nerve damage.
Alternatively it can come from the symptoms and strains they place on your body. Such pain can feel like burning, stabbing, sharp and squeezing sensations, says the MS Society.
MS sufferers can experience both acute (a rapid onset and of short duration) neuropathic pain and chronic neuropathic pain.
Acute neuropathic pain is occasionally an initial symptom of MS, or could be part of an MS relapse.
Bladder problems
There are two main types of bladder problems in MS: problems with storage and issues with emptying.
The MS Society says that when the nerve pathways in the spine are interrupted, even a small amount of pee in the bladder can cause it to contract.
This causes a need to pee frequently.
Bowel trouble
Some people with MS will never experience such a problem, but around 7 in 10 people with the condition will get a bowel issue at some stage - either constipation or incontinence.
Memory and thinking
Problems with memory and thinking - also called 'cognitive problems' - can affect people with MS, but most people will be affected mildly. Some people find it harder to find the right words, to concentrate or to recall things quickly.
