Summer 2001: Volume 10, Number 2
Pain and Spinal Cord Injury: Causes and Treatments
Chronic pain is a frequent problem in the majority of the SCI population and can occur not only above the level of injury but also at or below the level of injury and in both complete and incomplete injuries. In a recent study at the UW, 82% of patients with SCI reported persistent, bothersome pain at some time after discharge from their initial inpatient rehabilitation. Post-SCI pain can be so severe and disabling that some patients have said they would give up the possibility of neurological recovery in favor of pain relief.
An individual with SCI is likely to experience many types of painful sensations at or below the level of injury that can be troublesome to categorize, making effective treatment difficult.
Neuropathic painthe most common type of chronic pain with SCIresults from the abnormal processing of sensory input due to damage to the nervous system. It is often difficult to identify a specific stimulus or cause of neuropathic pain, and this type of pain is notoriously unresponsive to conventional methods of pain treatment.
Nociceptive pain is the result of the normal processing of stimuli that damage or disturb normal tissues. Nociceptors are nerve fibers that carry signals to the spinal cord. Unlike neuropathic pain, nociceptive pain has an identifiable cause, either from musculoskeletal problems such as bone fractures and rotator cuff tears, or from visceral (abdominal) problems.
Musculoskeletal disorders are a frequent cause of pain and disability in the SCI population. Musculo-skeletal pain can be caused by injury at the time of SCI, injury following SCI, chronic disorders related to overuse, and problems related to aging.
Musculoskeletal pain at or below the level of injury is usually described as dull or aching and well-localized (confined to one specific area). It often worsens with activity, diminishes with rest, and responds well to non-steroidal anti-inflammatory drugs (NSAIDs, e.g., ibuprofen), ice, and rest.
Visceral complaints often are caused by undiagnosed gastrointestinal complications such as ulcers, constipation, or appendicitis. Pain is usually poorly localized and can be associated with increased spasticity, overall discomfort, anorexia, nausea, fever, bloating, and changes in bowel habits. Depending on the level and completeness of the injury, however, the person with SCI may not experience acute pain or other symptoms usually associated with abdominal problems, and clinicians with limited experience caring for SCI patients may have difficulty making the correct diagnosis. On the other hand, visceral pain can also exist in the absence of pathology and may instead be a result of neuropathic pain that is felt in the abdomen.
Whereas in nociceptive pain nerve pathways are functioning normally, neuropathic pain is caused by nerve damage, and includes transitional zone pain, SCI pain, and radicular pain. There is often a great deal of confusion when attempting to sort out these pain types since many can exist simultaneously.
Transitional zone pain (also called segmental pain) is usually felt at the level of injury in a band-like pattern over the trunk or it may involve the upper extremities. Transitional zone pain is sometimes treated with a surgical procedure called DREZ (dorsal root entry zone lesion), but there is disagreement among neurosurgeons about the efficacy of this treatment.
Radicular pain can be felt at any level and is caused by nerve root damage commonly due to bony fragments, extruded disk material, or inflammation. Radicular pain tends to be one-sided and is frequently described as shooting, burning, aching, or crushing. It can worsen with rest and improve with activity. The onset of pain is often within days to weeks after injury and can be hard to distinguish from pain caused by the injury itself. Radicular pain can be responsive to treatment with NSAIDs.
SCI pain (also called central, dysesthetic, or diffuse pain) is neuropathic pain below the level of injury and is commonly described as burning, tingling, shooting, stinging, stabbing, piercing, cutting, crushing, aching, and nagging. The pain is often diffuse and poorly localized and is more common with gun shot wounds, advanced age, increased anxiety, and adverse psychosocial situations, and may be exacerbated by fatigue, tobacco use, stress, overexertion, bowel or bladder complications, pressure sores, spasticity, and weather changes.
Onset of SCI pain is usually weeks to months after injury. Late onset or worsening SCI pain should be evaluated for possible syringomyelia, Charcot spine, or other bony pathology, although a cause is rarely found.
SCI pain is one of the most common types of pain in the SCI population and is usually unresponsive to standard pain treatments. Few research studies have examined SCI pain and so far none has shown any drug to be effective for a significant number of people. Even so, individuals with SCI have found pain relief, sometimes from a combination of drugs, sometimes from drugs in combination with physical therapy or other treatment modalities. Some treatments, like implanted morphine pumps, work well but only temporarily. Until a widely effective treatment for SCI pain is found, physicians need to work with each patient to develop an individual treatment plan. Often a holistic approach, encompassing exercise, medication, stress reduction, or complementary medicine (e.g., acupuncture), can be beneficial in managing SCI pain.
Diana D. Cardenas, MD, MHA
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