Chapter 10

Pain management

Pain is a common complication of spinal cord injury which not only limits ability to perform motor tasks, but also has important implications for quality of life, well-being and general feelings of happiness.1–6 Physiotherapy is one component of a comprehensive pain management programme which typically involves pharmacological, surgical, psychological and behavioural interventions.

There are many different types of pain which occur in association with spinal cord injury, and the characteristics, patterns of presentation, intensity and location are highly variable. Some types of pain present at the time of spinal cord injury while other types of pain have a more insidious onset and can present years later and involve many different areas of the body. In some circumstances pain resolves quickly with minimal intervention but at other times it appears unresponsive to any intervention, and evolves into a chronic problem adversely affecting all aspects of patients’ lives.

Pain associated with spinal cord injury can be categorized as either nociceptive or neuropathic (see Table 10.1).⁷^,⁸ Neuropathic pain arises from primary lesions of the nervous system and the associated neural dysfunction, while nociceptive pain originates from musculoskeletal or visceral structures. Our understanding of the under-lying causes of neuropathic and nociceptive pain in patients with spinal cord injury is limited. There is some evidence to suggest that changes within the central nervous system following spinal cord injury lead to a heightened sensitivity (or neuronal excitability) and this contributes to the development of pain. Pain may have its origins at the receptor level or may be due to abnormal firing of neurons in the central nervous system either as a result of increased excitability through receptor changes or disruption of normal local and descending pain inhibitory pathways.⁶ However, most studies looking at prevalence and causative factors use cross-sectional rather than longitudinal designs, making even the identification of key prognostic factors problematic.⁶ The few more recent longitudinal studies have primarily looked at predictors of pain during the first 1–2 years after injury.⁴

Table 10.1

Classification of pain associated with spinal cord injury proposed by the Spinal Cord Injury Pain Task Force of the International Association of the Study of Pain ⁸

Broad type	Broad system	Specific structures/pathology
Nociceptive	Musculoskeletal	Bone, joint, muscle trauma or inflammation
		Mechanical instability
		Muscle spasm
		Secondary overuse syndromes
	Visceral	Renal calculus, bowel, sphincter dysfunction, etc.
		Dysreflexic headache
Neuropathic	Above-level	Compressive mononeuropathies
		Complex regional pain syndromes
	At-level	Nerve compression (including cauda equina)
		Syringomyelia
		Spinal cord trauma/ischaemia (transitional zone, etc.)
		Dual level cord and root trauma (double lesion syndrome)
	Below-level	Spinal cord trauma/ischaemia

Reproduced from Siddall P, Yezierski RP, Loeser JD: Pain following spinal cord injury: clinical features, prevalence, and taxonomy. Technical Corner Newsletter of the International Association for the Study of Pain 2000; 3:3–7, with permission of The International Association for the Study of Pain.

Assessment

The first and most important purpose of a pain assessment is to ensure that there is no reason for serious concern (e.g. fractures, infections, tumours, syringomyelia ⁹).If in any doubt, patients should be assessed by a medical specialist. Symptoms which may indicate the need for further medical investigation include deterioration in motor, sensory, bladder or bowel function, recent loss of weight, deterioration in ‘balance’, raised temperature and night sweats. Aspects of the history which may suggest a more sinister underlying cause of pain include history of acute trauma, use of corticosteroids and history of cancer.¹⁰ It is also important to remember that patients with spinal cord injury are typically osteoporotic, and even minor physical injuries can cause fractures (see p. 21).

The assessment of pain relies on patient self-report about the characteristics of their pain, associated symptoms, activity limitations and participation restrictions (see Table 10.2).

The common measures used to quantify pain intensity are the visual analogue scale ¹¹ and the numerical rating scale.¹² Pain drawings can be used to identify the distribution of pain,¹³ and the McGill Pain Questionnaire¹⁴ can be used to assess the quality of the pain. There are also various questionnaire-based assessments for neuropathic pain.¹⁵ Other symptoms, such as reduced joint mobility, can be assessed using standard assessments of impairments (as outlined in previous chapters).

A pain assessment also needs to determine the implications of pain on activity limitations and participation restrictions. This is not only important for understanding the implications of pain on different aspects of patients’ lives, but also for establishing a baseline measure upon which change can be monitored. This is particularly important in patients with chronic pain. Often interventions do not change the characteristics of pain but rather change pain-related behaviours and coping mechanisms.¹⁶ These changes can be captured in measures of activity limitations and participation restrictions such as the Functional Independence Measure, Quadriplegic Index of Function, Spinal Cord Independence Measure or Barthell (see Chapter 2). An assessment specific to shoulder pain in patients with spinal cord injury is The Wheelchair User’s Shoulder Pain Index.¹⁷ This quantifies implications of shoulder pain on different aspects of patients’ mobility and life.

It is often also helpful for physiotherapists to consider the biopsychosocial dimension of pain, including the contribution of psychological, social and behavioural factors.¹⁸^,¹⁹ Examples of measures which capture some of these dimensions of pain include the Pain Self-Efficacy Questionnaire,²⁰ the Fear-avoidance Beliefs Questionnaire,²¹ the SF-36²² and the Multidimensional Pain Inventory.¹⁵^,²³

Neuropathic pain

Neuropathic pain is a term used to encompass many different syndromes of pain, and includes pain due to compressive mononeuropathies, nerve root compression and syringomyelia, as well as spinal cord trauma. The pain can be above, at, or below the level of the lesion. Typically, neuropathic pain is described as burning, electric or stabbing pain, difficult to alleviate by activity or change of position. It is commonly associated with increased sensitivity to touch or any other type of physical contact. Sometimes this type of pain occurs in two to four dermatomes between areas of no sensation and areas of normal sensation (at-level neuropathic pain). In this case, the neuropathic pain commonly presents soon after injury, and is bilateral and circumferential. Alternatively, the pain can be felt more diffusely in areas without sensation below the level of the lesion (below-level neuropathic pain). Other terms used to describe this latter type of pain are central dysaesthesias syndrome, dysaesthetic pain, central pain or phantom pain.

Neuropathic pain is difficult to treat, and is largely managed pharmacologically, although the small number of clinical trials in this area have generated conflicting results.⁶^,²⁴ There is some limited evidence to suggest that physiotherapy-type interventions designed to desensitize the affected dermatomes may be useful. TENS is also widely advocated, but currently without good evidence. Perhaps the largest role for physiotherapy, in patients with this type of pain, is encouraging graded exercise and activity to minimize secondary impairments and activity limitations. It is particularly important to ensure patients do not develop secondary contractures from holding limbs in protected positions (see Chapter 9).

Nociceptive pain

Nociceptive pain can be due to trauma, disease or inflammation of musculoskeletal or visceral structures. Physiotherapy interventions used to manage nociceptive pain include exercise, massage, stretch, re-education and guided return to activity.²⁵ A recent Swedish study indicated that 63% of patients with spinal cord injury-related pain tried one or other of these types of pain-relieving interventions.²⁵ Below is a summary of some of the more common musculoskeletal problems seen in patients with spinal cord injury (readers interested in pain from visceral origins are directed to Ref. 26).

Back or neck pain associated with initial injury

Back and neck pain are common immediately after injury, and particularly in patients with extensive disruption to bony and ligamentous structures of the spine. This type of pain can be due to mechanical instability or the direct effects of extensive soft tissue trauma. It is typically managed with immobilization, pain-relieving medication and/or surgery. Medical staff determine when patients can mobilize after injury, but within these guidelines physiotherapists need to encourage activity to prevent secondary disablement. The use of hot packs with or without gentle superficial massage once patients have mobilized may provide some temporary pain relief and will often provide general comfort. However, therapists need to obtain medical clearance if there is any risk that their interventions will cause movement at the injury site and hot packs should not be applied to areas with impaired sensation.

Chronic back or neck pain

If back or neck pain persists for more than 3 months without any apparent underlying cause and develops into chronic pain, then it may be appropriate to use the existing clinical guidelines on the management of chronic neck and back pain advocated for the able-bodied population but modified in an appropriate way.27–31 These guidelines are based on high quality evidence and recommend minimal use of passive interventions, such as massage, electrotherapeutic agents or manual therapies, but rather appropriate, graded and supported return to active exercise and ‘normal’ activity, combined with reassurance about good prognosis. These guidelines do not recommend continued, ongoing and detailed physiotherapy-type assessments, unless there is reason to be concerned. They also highlight the futility of trying to make a precise diagnosis on the source of musculoskeletal pain and emphasize the importance of early efforts at minimizing fear, providing reassurance and encouraging graded return to activity.³² While these guidelines have not been systematically evaluated in patients with spinal cord injury, they would seem a reasonable starting point in the absence of more specific and relevant research. At least one clinical trial indicates the benefits of encouraging activity and exercise for relieving chronic pain in patients with spinal cord injury.³³

Recent attention has been directed at determining the most effective way to treat and prevent shoulder subluxation, although most of the clinical trials in this area have been with patients following stroke, not spinal cord injury.⁴²^,⁴⁴ Some studies indicate that shoulder support reduces subluxation⁴⁵ but does not decrease pain, while others show a treatment effect on pain but not subluxation.⁴² A recent Cochrane systematic review concluded that, in patients with stroke, there is insufficient evidence to indicate whether supportive devices prevent subluxation, although they may delay the onset of shoulder pain.⁴⁶ Regardless, therapists are well advised to ensure that the arm troughs of wheelchairs are appropriately adjusted to provide shoulder support. Shoulder support can also be provided with pillows, strapping, lap boards, slings or shoulder harnesses (see Figure 10.1).⁴²^,⁴⁵^,⁴⁷