The disruption of nerve signals produces the primary symptoms of MS, which vary depending on where the damage has occurred. Over the course of the disease, some symptoms will come and go, while others may be more lasting. Some symptoms of MS are much more common than others.
Visual disturbance is the first symptom of MS for many people, most commonly impairment of vision in one eye (occasionally both), often with pain on moving the eye (optic neuritis due to inflammation in the optic nerve). Double vision may also occur.
The most common symptoms (along with visual) – typically a feeling of numbness in the limbs or face, often associated with unpleasant tingling, with impairment of sensation to touch, pinprick, and temperature. Less disabling than weakness, but often persistent and disturbing.
Pain syndromes are common in MS and may be acute and transient or persistent. Recurrent brief pains may be severe – often affecting one side of the face (trigeminal neuralgia) or the limbs respond to medication.
More common is persistent burning pain in the limbs associated with damage to sensory nerve pathways. A complicating problem is secondary pain arising from stiff joints related to limited mobility and spasticity.
Weakness affecting the legs more than the arms is the most common cause of motor disability. It is usually associated with spasticity of variable severity, which refers to a feeling of stiffness and slowness of movement in the limb and may also affect the trunk.
Spasticity is often accompanied by involuntary muscle spasms, at times painful, which may be sustained or brief and triggered by movement. Medication may help spasticity and spasms but does not affect weakness.
A constellation of symptoms which are more common later in the course of MS and may be substantially disabling. Clumsiness of limb movement with associated shaking (tremor) may be separate from weakness and is due to involvement of separate motor pathways.
It is often associated with unsteadiness on walking and dysarthria. There is no known effective treatment.
Bladder dysfunction, which occurs in up to 80% of people with MS, can usually be managed quite successfully with medication, but when more severe may require intermittent or sustained use of catheter drainage.
Constipation may be a problem, with bowel urgency and diarrhoea being much less common.
Sexual problems are often experienced by people with MS. Sexual arousal begins in the central nervous system, as the brain sends messages to the sexual organs along nerves running through the spinal cord.
If MS damages these nerve pathways, sexual response, including arousal and orgasm, can be directly affected. Sexual problems also stem from MS symptoms such as fatigue or spasticity, as well as from psychological factors relating to self-esteem and mood changes.
Problems with speech and swallowing occur most commonly in persons with more severe MS affecting mobility The main disturbance of speech is dysarthria with slurring and unclear articulation of words.
Difficulty swallowing or dysphagia, results from impairment of motor control of the muscles in the mouth and throat. When dysphagia occurs, food and liquids may pass into the airway, causing the person to cough and choke. Particles that remain in the lungs can cause aspiration pneumonia.
Evaluation and management by a speech/language therapist are very helpful.
MS can affect a person’s ability to think and remember. Common observations include: “I find it very hard to concentrate”, “I often can’t find the words I want to use”, “I have trouble remembering names of people”.
The technical term for problems with thought processes is ‘cognitive dysfunction’. Cognition refers to a range of high-level brain functions, including the ability to learn and remember information, organise, plan, and solve problems.
The ability to concentrate, the use of language and accurately perceiving the environment are also cognitive functions.
Approximately 50% of people with MS will develop problems with cognition, with severity usually being mild rather than severe.
Emotional changes are very common in MS. This may be a reaction to the stresses of living with a chronic unpredictable illness or because of neurologic and immune changes associated with the disease.
Common problems include depression, anxiety, mood swings, and irritability. Episodes of uncontrollable laughing and crying (called pseudobulbar affect) may occur in persons with established motor disability and pose significant challenges for people with MS and their family members.
General fatigue is one of the most common symptoms of MS, occurring in about 80% of people at some stage. It is a complex symptom of unclear cause in MS, which is not related to the degree of neurologic impairment, nor clearly to the occurrence of active inflammation. Fatigue can significantly interfere with a person’s ability to function at home and at work and may be the most prominent symptom in a person who otherwise has minimal activity limitations.
A person with MS will usually experience more than one symptom but NOT necessarily all of them.