RECOGNITION OF PAIN WITH MS
Yes, pain does occur in multiple sclerosis. However, recognition of pain as a genuine symptom of the disease has only come about in the past 10 or 20 years. The prevalance for MS pain syndromes is quite variable with estimates ranging from 10 to 80%.
Recent studies estimate that about half of people with MS will experience some type of pain during the course of their illness.There is no relationship between pain and the type of MS. Pain occurs equally in relapsing/remitting and progressive disease.
The cause of MS pain is dependent upon the type of pain syndrome. There are three categories or types of pain syndromes in MS: acute, subacute, and chronic.
Acute pain syndromes are often described as paroxysmal attacks, that is, sudden attacks of pain. They are time-limited, usually repetitive pain attacks lasting minutes or hours. The symptom is a result of abnormal conduction or "short circuit" along demylinated nerve fibres.
The nerve impulse may jump to adjacent demylinated sensory fibres causing a painful sensation. The most recognized acute pain syndrome is trigeminal neuralgia. It is a stabbing, shock-like pain usually extending from the ear to the mouth.
Pain can be provoked by facial movement such as speaking or chewing, but can also be caused by exposure to wind, temperature or touch.
Other acute pain syndromes include Lhermitte's symptom (electrical sensation passing down the back when you flex your head forward) and paroxysmal (brief) pain in the arms and legs. These symptoms are usually triggered by touch, movement or even hyperventilation (rapid breathing).
When treating acute pain syndromes with drugs, doctors turn first to anticonvulsant medication. Carbamazepine (Tegretol) is the first drug of choice. Other drug therapies include Gabapentin and Dilantin. These medications block abnormal conduction at the demylinated site in the central nervous system.
Unfortunately, because they block conduction they may cause worsening of other symptoms such as weakness or tremor. Medication side effects can be reduced if the drug is introduced gradually to achieve pain control or tolerance.
Generally, these acute pain syndromes are time-limited, but may last days to weeks. Many people will tolerate annoying medication side effects to manage their pain during this period.
Subacute pain syndromes are caused either directly from demylination or from a secondary source. They are also time-limited, lasting days to weeks. The most common direct subacute syndrome is the pain associated with optic neuritis. This is an aching, throbbing pain around or behind the eye provoked by eye movements.
This eye pain is probably the result of pressure on the meninges (pain sensitive tissue covering the brain) surrounding the optic nerve.
Treatment is often corticosteroids (Solumedrol or prednizone) to reduce optic nerve swelling.
Indirect MS pain would be painful bladder spasms associated with a neurogenic bladder or bladder infection. Pain can also result from frequent or prolonged treatment with corticosteroids and/or prolonged immobility. They can cause painful compression fractures of the vertabrae (backbone) or in pressure ulcers (sores).
Treatment focuses on specific symptoms - medications to relax the bladder or to treat infection - and education to prevent or reduce complications.
Chronic pain syndromes make up about 50 - 80% of all pain experienced in MS. Chronic pain can be both directly and indirectly caused by MS. There are two forms of chronic pain: neuropathic and musculoskeletal.
Central neuropathic pain is well recognized in MS and occurs in about 30% of people with MS. It is believed to be the direct result of demylination of the sensory pathways of pain and temperature. However, it is unlikely that a single sensory pathway is totally responsible. It is suspected there are multiple sensory pain pathways involved, but the exact mechanism is poorly understood.
The description of neuropathic pain varies and is often hard for people to describe. The most common description is a freezing or cold/burning sensation usually of the limbs and most often of the lower extremities.
Others describe the pain as deep, aching, throbbing or sqeezing sensations. Most agree this syndrome is very painful. Pain occurs spontaneously or can be provoked by touch, temperature or movement. Water from a bath or clothing touching the skin can provoke pain (this is called allodynia). For many people their pain is continuous with varying degrees of intensity and is usually worse at night.
When looking at drugs available to treat neuropathic pain, tricyclic antidepressants are the first choice of treatment. Of these, amitriptyline is most frequently used for its pain reducing and sedating properties. Similar drugs such as nortriptyline or desipramine are used when the side effects of sedation or dryness that can occur with amitriptyline are poorly tolerated.
Tricyclic antidepressants work because they block the normal function of serotonin. It is one of the chemical substances of the nervous system involved in nerve impulse transmission.
If these medications fail, then other therapies with anticonvulsants, narcotics or the antispacticity drug baclofen can be tried. Combined drug therapies may provide better relief, however, there is a greater risk for increased medication side effects.
Appropriate dosing is key in controlling neuropathic pain. Generally, people require high doses to achieve some benefit, and unfortunately, higher doses can result in more side effects.
Pain reduction can also be achieved with therapies that don't involve medication. These include stimulation techniques (either on the skin or surgically implanted devices), physiotherapy, relaxation and behavioral modification. Counselling can have additional benefits in providing coping strategies.
Most health care practitioners and people with MS would agree that neuropathic pain is the most difficult of pain syndromes to treat. The goal of therapy is to provide some control over the pain so the pain does not control one's life. Finding the therapy or therapies that work best can be a slow and difficult process. It is a matter of trial and error which is helped by an understanding that complete pain relief is unlikely.
Indirect Chronic Pain
Other chronic pain syndromes such as backache and painful leg spasms are an indirect result of MS. It is estimated that chronic back pain occurs in about 20% of people with MS. It generally affects the lower back and may radiate to hips and thighs. Factors such as poor posture in walking or sitting can put added strain on already wekened muscles of the lower back. Reduced mobility can accelerate degenerative disc disease. These factors may also contribute to localized joint pain.
Non-steroidal anti-inflammatory medication (NSAIDS) and physiotherapy are the two most effective treatments for chronic back pain. Therapy is important to provide stretching and strengthening exercises as well as correct posture.
An occupational therapist can assess proper seating for the work environment and wheelchair. Correct posture is very important in relieving mechanical stresses in the spine and surrounding muscles. Remember, your mother always told you to "Sit up straight"!
Spasms are associated with spasticity(muscle stiffness), but they are not the same thing. Spasms that cause drawing or pulling up of limbs are more likely to cause discomfort. These spasms often produce sensations of intense cramping or pulling.
Spasms are generally associated with increased disability and immobility, which also may lead to problems with constipation, bladder infections and pressure sores. These problems may aggravate leg spasms.
Painful spasms are best managed with anti-spasticity medication and physiotherapy. Anti-spasticity drug therapies help to relax muscle contractions by suppressing excitable neurons in the spinal cord.
In proposing possible medication for painful spasms, doctors often suggest baclofen, which remains the first choice of drug therapies. However, it may cause weakness and drowsiness. Dosing requirements are variable between people and should be introduced gradually to reduce side effects. Baclofen is taken orally, but in severe cases can be administered via a surgically implanted pump. Other drug therapies used to treat spasms are Zanaflex (tizanidine), diazepam and dantrolene.
Again, the important role of physiotherapy in managing limb spasms must be stressed. Therapists can educate people with MS, family members and caregivers on strengthening and stretching exercises. These exercises should be done daily for maximum benefit.
Pain is a common and at times very debilitating symptom of MS. It is a subjective symptom, which makes it difficult to assess and treat. The pain experience can be quite different between people, and what works for one may not work for another.
Given the complex nature of MS pain syndromes, the approach to effective management can involve many therapies and approaches with the hope to maintain function and quality of life.