Pain

What is pain? The International Association for the Study of Pain defines it as: An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage. This description is a bit less personal and doesn't seem to hurt as bad.

A more personal description of pain is an unpleasant feeling that is conveyed to the brain by sensory neurons. The discomfort signals actual or potential injury to the body. However, pain is more than a sensation, or the physical awareness of pain; it also includes perception, the subjective interpretation of the discomfort. Perception gives information on the pain's location, intensity, and something about its nature. The various conscious and unconscious responses to both sensation and perception, including the emotional response, add further definition to the overall concept of pain.

To take this a step further, a neurological description of pain is when the sensory system is impacted by injury or disease, the nerves within that system can't work to transmit sensation to the brain. This often leads to a sense of numbness, or lack of sensation. However, in some cases when this system is injured, individuals experience pain in the affected region. This type of pain doesn't start abruptly or resolve quickly but is rather a chronic condition which leads to persistent pain symptoms.

Depending on what is the cause of an individuals pain will typically determine how severe it is. For many with multiple sclerosis (MS), they will suffer from a clinically significant amount of pain at some time. For many, the pain that they deal with becomes more chronic.

Causes of MS Pain

Pain in MS is directly related to either an MS lesion or plaque in the nervous system (nerve pain), or the effects of disability. When MS makes moving about difficult, stress on muscles, bones and joints can cause pain (musculoskeletal pain). Pain in MS can be caused or worsened by infection, or pressure ulcers.

Nerve pain can be continuous and steady or sudden and irregular. Nerve pain is reported in varying degrees of severity. 50% of those who report MS pain say their pain is constant and severe. Intermittent, sudden pain is described as shooting, stabbing, electric shock-like, or searing and is often caused by sensations that normally do not cause pain like the weight of bed covers, chewing, or a cold breeze. Other examples of intermittent pain include the feelings of tightness, cramping, clawing, and sudden spasms of a limb.

Tightness or band-like feelings, nagging, numbness, tingling in legs or arms, burning, aching, and throbbing pain is termed constant or steady nerve pain. Steady nerve pain is often worse at night or during changes in temperature, and can be worsened with exercise. The most common pain syndromes experienced by people with MS include: headache (seen more in MS than the general population), continuous burning pain in the legs and/or arms, back pain, and painful spasms.

Types of Pain

It's useful to distinguish between two basic types of pain, acute and chronic, and they differ greatly.

•	Acute pain typically results from disease, inflammation, or injury to tissues. This type of pain generally comes on suddenly, like after trauma or surgery, and may be accompanied by anxiety or emotional distress. The cause of acute pain can usually be diagnosed and treated, and the pain is self-limiting, in that it's confined to a given period of time and severity. In some rare instances, it can become chronic.

•	Chronic pain is widely believed to represent disease itself and can be made much worse by environmental and psychological factors. Chronic pain persists over a longer period of time than acute pain and is resistant to most medical treatments. It can, and often does, cause severe problems for patients. A person may have two or more co-existing chronic pain conditions. Such conditions can include chronic fatigue syndrome, endometriosis, fibromyalgia, interstitial cystitis, and MS just to name a few.

When most people think of MS, they think of a disease that causes symptoms of weakness and motor problems and not pain. Pain is both a biochemical and neurological transmission of an unpleasant sensation and an emotional experience.

It's estimated that at least 70% and possible as many as 90% of those with MS experience pain at some point during the course of the disease and around 50% are never pain free with clinically significant pain. MS causes many pain syndromes with some being acute while others are chronic. Some types of pain worsen with age and with disease progression. Pain syndromes associated with MS are typically trigeminal (facial) pain, powerful spasms and cramps, optic neuritis (pain in the eye), pressure pain, stiffened joints, and a variety of sensations including feelings of itching, burning, and shooting pain.

MS is a type of neuropathic pain being that it's a chronic pain that usually is accompanied by tissue injury. With neuropathic pain, the nerve fibers themselves may be damaged, dysfunctional or injured. These damaged nerve fibers send incorrect signals to other pain centers. The impact of nerve fiber injury includes a change in nerve function both at the site of injury and areas around the injury.

Like fatigue, pain is often described as one of the worst symptoms of MS. The presence of pain tends to be independent of gender, age at onset and examination, disability, disease course and duration. About 40% of those with pain symptoms say that it had important influence on their daily activities.

Steady and achy type pain often results because muscles become fatigued and stretched when they are used to compensate for muscles that have been weakened by MS. People with MS may also experience more stabbing type pain which results from faulty nerve signals emanating from the nerves in MS lesions in the brain and spinal cord.

Pain from awkward positions is called "musculoskeletal dysfunction". It results from unusual positioning of the body caused by MS symptoms like hip, knee, or low back pain can stem from an odd standing position that a person has developed in an attempt to maintain balance. Fatigue can make this kind of pain even worse. Overuse of certain muscles to compensate for other muscles can also lead to pain.

Chronic Pain from MS

Chronic pain usually is typically caused by an initial trauma/injury or infection, or there may be an ongoing cause of pain. With MS, the signals of pain remain active in the nervous system for weeks, months, or even years.

Types of chronic pain caused by MS:

Neuropathic

Nerve pain caused by an injury or dysfunction in the central nervous system (CNS). MS attacks the CNS and damages nerve fibers. This damage can decrease the body's ability to correctly process pain signals and may lead to chronic pain. Symptoms of neuropathic pain are often described as paresthesias.

Non-neuropathic

This pain includes joint and muscle pain and stiffness. This type of pain is a result of muscle weakness, poor posture, or abnormal use of muscles or joints due to muscle spasms or continuous muscle contractions caused by MS.

The emotional toll of chronic pain also can make pain worse. Anxiety, stress, depression, anger, and fatigue interact in complex ways with chronic pain and may decrease the body's production of natural painkillers; moreover, such negative feelings may increase the level of substances that amplify sensations of pain, causing a vicious cycle of pain for the person. Even the body's basic defenses may be compromised in the form of a suppressed immune system.

The symptoms of chronic pain include:

•	Mild to severe pain that does not go away
•	Pain described as shooting, burning, aching, or electrical
•	Feeling of discomfort, soreness, tightness, or stiffness

Pain is not a symptom that exists alone. Other problems associated with pain include:

•	Fatigue
•	Sleeplessness
•	Withdrawal from activity
•	Increased need to rest
•	Weakened immune system
•	Changes in mood
•	Anxiety and stress
•	Depression and irritability
•	Disability

Central Pain Syndrome

Central pain syndrome (CPS), also called neuropathic pain, is a neurological condition caused by damage to or a dysfunction of the CNS. The pain is typically constant, may be moderate to severe in intensity, and is often made worse by touch, movement, emotions. It's often aggravated by temperature changes, particularly cold. CPS may affect a large portion of the body or may be more restricted to specific areas, such as hands or feet. The extent of pain differs widely among individuals partly because of the cause of the CNS injury or damage.

Individuals with CPS may experience one or more types of pain sensations, with the most prominent being burning due to paresthesis. Mingled with the burning may be sensations of "pins and needles" like a pressing, lacerating, or aching pain; and brief, intolerable bursts of sharp pain similar to the pain caused by a dental probe on an exposed nerve.

CPS may also have intense skin reactions that can accompany these symptoms, such as a burning, stretching, tightness, itching, or a crawling feeling that can be sensitive to or irritated by any light touch, such as the feel of cloth on skin, which can make getting dressed an ordeal. Sometimes the simple act of a touch by someone may often be a way to overwhelm the brain with pain.

In CPS, sometimes the hands and feet are affected with a numbness that is painful, and doesn't offer any relief, but rather only adding to the pain. Individuals may also have numbness in other areas affected by pain. The burning and loss of touch sensations are usually most severe on the distant parts of the body, again usually in the feet or hands.

CPS often begins shortly after the causative injury or damage, but may be delayed by months or even years. In many cases, when a person rates the pain as high as a 9 or 10 on a pain scale, there seems to be no relief even with medications.

Transverse Myelitis

Transverse myelitis occurs when the immune system attacks a section of the spinal cord. Damage to the spinal cord is known as a myelopathy. The hallmark of a myelopathy is a sensory level. This means that there is a location on the patient below which the patient feels numb and above which sensation is normal. Sometimes this is only on one side of the body. It's also common to have weakness in the parts of the body below the level and normal strength above. In some cases of myelopathy, there are problems with controlling ones bowels and bladder.

In some people, transverse myeltis represents the first symptom of an underlying demyelinating disease of the CNS such as MS or neuromyelitis optica (NMO). A form of transverse myelitis known as "partial" myelitis, because it affects only a portion of the cross-sectional area of the spinal cord, is more characteristic of MS.

Neuromyelitis optica typically causes both transverse myelitis and optic neuritis (inflammation of the optic nerve that results in visual loss), but not necessarily at the same time. All those with transverse myelitis should be evaluated for MS or NMO because those with these diagnoses may require different treatments, especially therapies to prevent future attacks.

There's a large differential for myelopathy and typically having a MRI will sort out most of the causes. Once it's identified to be a transverse myelitis, then one has to determine if it's part of MS, neuromyelitis optica, idiopathic (meaning all by itself) or as a consequence of a systemic disease such as lupus. If there is sufficient symptoms to warrant therapy, then a high dose of IV steroids is typically given. If the transverse myelitis appears to be the first attack of MS, then standard MS disease modifying medications are started. If it's over multiple spinal cord segments, then neuromyelitis optica needs to be considered.

No effective cure currently exists for those with transverse myelitis. Corticosteroid therapy is usually begun during the first few weeks of illness to decrease inflammation. Following initial therapy, the most critical part of the treatment for this disorder consists of keeping the patient's body functioning while hoping for either complete or partial spontaneous recovery of the nervous system. If an individual begins to recover limb control, physical therapy begins to help improve muscle strength, coordination, and range of motion.

Trigeminal Neuralgia

Trigeminal neuralgia, also called tic douloureux, is a chronic stabbing pain condition that affects the trigeminal or 5th cranial nerve, which carries sensation from your face to your brain. If you have trigeminal neuralgia, even mild stimulation of your face may trigger a jolt of excruciating pain. While it can be confused with dental pain, this pain is neuropathic in origin, meaning it's pain associated with nerve injury or nerve lesion.

You may initially experience short, mild attacks, but trigeminal neuralgia can progress and cause longer, more-frequent bouts of searing pain. Trigeminal neuralgia affects women more often than men, and it's more likely to occur in people who are older than 50.

In trigeminal neuralgia the trigeminal nerve's function is disrupted. Some people may experience trigeminal neuralgia due to a brain lesion or other abnormalities. Trigeminal neuralgia can occur as a result of aging, or it can be related to MS or a similar disorder that damages the myelin sheath protecting certain nerves. It may also occur as an initial symptom of MS. Usually, the problem is contact between a normal blood vessel — in this case, an artery or a vein — and the trigeminal nerve at the base of your brain. This contact puts pressure on the nerve and causes it to malfunction.

The typical or "classic" form of the disorder (called "Type 1") causes extreme, sporadic, sudden burning or shock-like facial pain that lasts anywhere from a few seconds to as long as two minutes per episode. These attacks can occur in quick succession, in volleys lasting as long as two hours. The "atypical" form of the disorder (called "Type 2"), is characterized by constant aching, burning, stabbing pain of somewhat lower intensity than Type 1. Both forms of pain may occur in the same person, sometimes at the same time. The intensity of pain can be physically and mentally incapacitating.

The trigeminal nerve is one of 12 pairs of cranial nerves. The nerve has three branches that conduct sensations from the upper, middle, and lower portions of the face, as well as the oral cavity, to the brain.

•	The ophthalmic, or upper, branch supplies sensation to most of the scalp, forehead, and front of the head.
•	The maxillary, or middle, branch stimulates the cheek, upper jaw, top lip, teeth and gums, and to the side of the nose.
•	The mandibular, or lower, branch supplies nerves to the lower jaw, teeth and gums, and bottom lip.

More than one nerve branch can be affected by the disorder. Rarely, both sides of the face may be affected at different times in an individual, or even more rarely at the same time (called bilateral).

Because of the variety of treatment options available, having trigeminal neuralgia doesn't necessarily mean you're doomed to a life of pain. Doctors usually can effectively manage trigeminal neuralgia with medications, injections or surgery.

Lhermitte's

Lhermitte's Sign, sometimes called the Barber Chair phenomenon, is an electrical sensation or shock that runs down your back and into the limbs. It's produced by bending the neck forward and/or backward. These electrical sensations are known as paresthesia and include tingling, buzzing, electrical shocks, partial numbness and sharp pains.

The problem can be painful, but it's not life-threatening and for some people it may go away over time and/or with treatment. Lhermitte's sign is caused by nerves that are no longer coated with myelin. These damaged nerves respond to the movement of the neck, which causes sensations from the neck to the spine. As with many MS symptoms, you're more likely to trigger it if you're tired or overheated. It can also happen if you move your head the wrong way, often when your chin hits your chest.

In MS, Lhermitte's is an indicator of lesions in the cervical spine. Movement of the neck causes the damaged nerves to be stretched and send erroneous signals. The symptoms can occur anywhere below the neck and many people with MS find that it can move around their body from one day to the next.

Lhermitte's sign is common in MS, but it's not exclusive to the disease. People with spinal cord injuries or inflammation, such as cervical spondylitis or disc impingement, might also feel symptoms of the condition. Severe vitamin B-12 deficiency can also cause symptoms of Lhermitte’s sign.

Medications can treat the symptoms of Lhermitte’s sign such as anti-seizure drugs and steroids. Anti-seizure drugs help manage the pain by controlling your body's electrical impulses. Your doctor might prescribe steroids if Lhermitte's sign is part of a general MS relapse. You might also take medication to lessen the nerve pain that is commonly associated with MS.

Paresthesia

Paresthesia includes "pins and needles," tingling, shivering, burning pains, a feeling of pressure, and areas of skin with heightened sensitivity to touch. The pains associated with this can be aching, throbbing, stabbing, shooting, gnawing, tingling, tightness and numbness. The cause of paresthesia is the direct damage to the nerves themselves (neuropathy) which itself can stem from injury, infection, or which may be indicative of a current neurological disorder.

Chronic paresthesia is often a symptom of an underlying neurological disease or traumatic nerve damage. Paresthesia can be caused by disorders affecting the CNS, such as stroke and transient ischemic attacks (mini-strokes), MS, transverse myelitis, and encephalitis. A tumor or vascular lesion pressed up against the brain or spinal cord can also cause paresthesia.

It can occur everywhere in the body, presenting the following problems:

•	Feet - causing problems walking because of pain, sensory ataxia and interference with proprioception
•	Hands - causing problems with writing, fine motor movements, holding things
•	Genitalia - causing sexual dysfunction
•	Tongue - causing problems speaking, such as dysarthria, or detecting temperature of food

Paresthesia in an arm has been described as having a blood pressure cuff inflated on your arm and not releasing the pressure. The pain, discomfort, burning and tingling sensations that most people experience for just a moment are what many with MS experience on a constant basis. For many this paresthesia is cronic and never goes away. In addition, it may be in just a single arm, both arms, both legs, the side of a face, or even an entire side of a persons body.

Many people (with or without MS) have experienced a mild and temporary paresthesia at some time when they have sat with legs crossed for too long, or fallen asleep with an arm crooked under their head. It can happen when sustained pressure is placed on a nerve and quickly goes away once the pressure is relieved. For many, they are lucky because it's only a temorary discomfort or pain, but this is an example of what those with MS experience on a constant basis.

This can also cause something as simple as writing a note or holding a beverage to become difficult if not impossible if it's located in an arm or hand. If it happens to be in a leg or foot, the challenge of walking can be a task without falling down. Then if it's affecting the face or mouth, a bowl of hot soup may become a "burning" experience, just like when getting a cavity filled at the dentist and you can't feel your face for an hour or so. For many it's a combination of these on top of a number of other issues.

Dysesthesia

Dysesthesia is the technical name for the burning, aching or "girdling" around the body that's sometimes referred to as the "MS Hug". It's a symptom of pain or abnormal sensations that typically cause hyperesthesia, paresthesia, or peripheral sensory neuropathy. Dysesthesia can be due to lesions in sensory nerves and sensory pathways in the CNS.

These painful sensations typically affect the legs and feet, but may also affect the arms and trunk, such as the feeling of constriction around the abdomen or chest area, which is where the term "MS Hug" comes from. They are neurologic in origin and are sometimes treated with antidepressants.

Three types of pain which occur secondary to MS

Musculoskeletal

Musculoskeletal pain can be due to muscular weakness, spasticity and imbalance. It's most often seen in the hips, legs and arms and particularly when muscles, tendons and ligaments remain immobile for some time. Back pain may occur due to improper seating or incorrect posture while walking. Contractures associated with weakness and spasticity can be painful. Muscular spasms or cramps called flexor spasms can be severe and discomfiting.

Paroxysmal

Paroxysmal pains are seen in about 5 to 10% of those with MS. The most characteristic is the facial pain of trigeminal neuralgia, which usually responds to carbamazepine. L'Hermitte's sign is a stabbing, electric shock-like sensation running from the back of the head down the spin brought on by bending the neck forward.

Chronic Neurogenic

Chronic neurogenic pain is the most common, distressing and intractable of the pain syndromes in MS. This pain is described as constant, boring, burning or tingling intensely. It usually occurs in the legs.