© Springer International Publishing Switzerland 2017
Alexios Carayannopoulos DO, MPH (ed.)Comprehensive Pain Management in the Rehabilitation Patient10.1007/978-3-319-16784-8_99. Pain in the Amputation Rehabilitation Patient
(1)
Department of Physical Medicine and Rehabilitation, Schwab Rehabilitation Hospital, 1401 S. California Blvd, Chicago, IL 60608, USA
Keywords
RehabilitationPain managementAmputationPhantom limbResidual limb painIntroduction
Pain can place a significant functional limitation on the lives of people with amputations. It can be difficult to treat, but with the use of a multimodal treatment paradigm, positive outcomes can be attained. This chapter will help to identify the differences between residual limb pain, phantom limb sensation, and phantom limb pain. There will be a discussion on the various treatment options, which include psychological management, physical and occupational therapy, medications, interventional procedures, and surgery.
Pathophysiology and Symptoms
Residual Limb Pain
A patient who requires an amputation of one of their limbs, or of another body part, is at risk of developing a variety of pain syndromes. One of the first postoperative complaints is residual limb pain. Residual limb pain is also known as stump pain, incisional pain, or surgical site pain. This type of pain is usually described as aching or throbbing and is localized to the residual limb. Pain typically subsides over a one to three-week time period.
The pathophysiology of residual limb pain occurs via nociceptive nerve fibers. It has been shown that incision of deep tissue, rather than skin alone, increases the amount of nociceptive transmission through the dorsal horn neurons. [1] These nociceptive nerve fibers are carried through the fast myelinated A-delta fibers, as well as non-myelinated C-fibers.
Other causes of pain in the residual limb include ischemia, infection, neuroma formation, and pressure points from bone spurs or pathologic bone formation. Residual limb pain in a later stage could be attributed to shear forces on adherent scars, a poorly fitting prosthesis, intermittent claudication, or other medical or neurological conditions.
Phantom Limb Sensation:
Phantom limb sensation [PLS] is very common in patients with amputation. The incidence is approximately 60–80% immediately after amputation [2]. Only about 10% of patients develop PLS after 1 month. The term PLS is reserved for individuals who have an awareness of the missing portion of their limb. PLS is not painful; therefore, it is rarely a clinical problem and usually diminishes over time. A variety of sensations may be felt, such as mild numbness and tingling, itching, or a feeling as if the amputated limb is in certain postures or is undergoing particular movements. There is also a phenomenon called “telescoping ,” in which the distal end of the missing limb feels as if it is retracted into the proximal end. Patients feel as if they can move the phantom limb [3]. This can be used as a form of therapy in an attempt to prevent phantom limb pain.
Normally, there is an extensive array of networks in the brain that are triggered by continuous incoming modulated flow from the periphery. When this flow ceases, cortical reorganization occurs, leading to non-painful phantom sensations triggered by input from body areas adjacent to the lost limb.
Phantom Limb Pain
The International Association for the Study of Pain (IASP ) defines phantom limb pain (PLP) as “pain referred to a surgically removed limb or portion thereof” [4]. Many patients will describe the pain as similar to other neuropathic pains, such as sharp, burning, stabbing, shooting, electric, squeezing, or knife-like. The pain may also feel the same as the pain that presented in the limb prior to amputation [5].
Seventy two percent of all patients with lower limb amputation report PLP [6]. Fifty percent of patients have pain within 1 week postoperatively. Pain may be delayed weeks, months, or years after the amputation [3]. Management of PLP may be challenging given that the pain is coming from a part of the body that is no longer present.
PLP is an extreme example of deafferentation. Deafferentation pain is considered to be the result of destruction of the spinothalamic tract, which transmits somatosensory information about pain, itch, and rough touch [7]. The theory behind PLP is thought to be related to neuroplasticity in the somatosensory cortex; there are plastic changes that occur just adjacent to the missing body part.
In the 1980s, Merzenich performed a series of experiments, in which he amputated the middle finger of adult monkeys and found that within 2 months, the area of cortex corresponding to this digit started to respond to touch stimuli delivered to the adjacent digits [8]. In long-term deafferentation of one upper limb, the cortical area originally corresponding to the hand is taken over by the sensory input from the face; the cells in the “hand area” now start responding to stimuli applied to the lower face region [8].
Advances in neuro-imaging and brain stimulation techniques have allowed further knowledge to be gained as to how these neuroplastic changes occur. Transcranial magnetic stimulation (TMS) is one method of noninvasive motor mapping. A coil is placed on the scalp over the primary motor cortex; a suprathreshold stimulation is applied and can then be measured by EMG. The coil can be moved up and down across the precentral gyrus (primary motor cortex) and can induce motor evoked potentials (MEP) in a somatotopic fashion.
Karl and colleagues used TMS to map motor representations in the primary motor cortex (M1) in people with amputated forearms. Their findings demonstrated that the areas on the contralateral M1 of the amputated arm had expanded representations of the body parts closest to the amputation, which included the upper arm and lip. They also discovered that the motor cortical representation of the missing limb is not completely gone. One hypothesis posits that the brain may interpret residual limb muscle contraction, and the resultant sensory information, as phantom limb movement [7].
Functional magnetic resonance imaging (fMRI) is another noninvasive brain mapping method. A study by Wrigley et al. [9] evaluated brain activity during sensory stimulation in spinal cord injury patients. The study showed that activity during sensory stimulation to the little finger was expanded into parts of the primary somatosensory cortex (S1) that would normally receive afferent information from the lower limbs.
Treatment and Potential Complications
Residual Limb Pain
Postoperative edema can contribute to residual limb pain. An immediate postoperative prosthesis (IPOP) is sometimes placed on the residual limb, in the operating room, to help prevent knee flexion contractures and to control edema. One concern with use of an IPOP is that it can lead to hygiene problems. Other more common options for edema control include elastic wrappings or stockinettes (e.g., ACE wraps or Tubigrip), residual limb shrinkers, rigid non-removable dressings, rigid removable dressings, and prosthetic silicone or gel liners [5, 10]. Problems with non-removable rigid dressings and IPOP include difficulty with inspection and desensitization. Other forms of compression, if applied incorrectly, could contribute to skin breakdown or a tourniquet effect.
As with any major surgery, postoperative pain may be significant. A stepwise approach to pain management should be utilized to treat residual limb pain in the rehabilitation setting. If the pain is mild, the patient’s pain may be controlled with acetaminophen. More likely, patients will have moderate to severe pain requiring opioids with or without acetaminophen. Opioids bind to mu, kappa, and delta in the central nervous system and peripheral tissues. They pre-synaptically lower the influx of calcium to reduce neurotransmitter release in sensory C fibers and post-synaptically increase the transport of potassium in the cell to facilitate hyper-polarization in second-order neurons.
Commonly used opioids include hydrocodone and oxycodone. Hydrocodone/acetaminophen combinations come in 5, 7.5, and 10 mg strengths of hydrocodone and patients may be prescribed one to two tablets, every 4–6 h, as needed for pain. The prescriber should be aware of the amount of daily acetaminophen consumption. Oxycodone/acetaminophen can be substituted, if hydrocodone is insufficient. The dosing is one to two tablets of oxycodone/acetaminophen, 5/325 mg, every 4–6 h, as needed for pain. Oxycodone, without acetaminophen, may also be used for breakthrough pain, if the patient is consuming higher amounts of acetaminophen or has liver dysfunction. Oxycodone immediate release may be dosed 10–20 mg, every 4–6 h, as needed for pain. [11].
Sustained-release opioid formulations are also available and may be used in combination with an immediate release opioid for optimal pain relief. In addition, it may be advantageous to schedule pain medications prior to therapy so that the patient can obtain the most benefit during their sessions [5]. The more commonly used sustained release opioids include sustained release morphine sulfate, dosed at 15 mg increments, every 12 h, and sustained release oxycodone, dosed at 10 mg increments, every 12 h. Potential side effects of opioids include nausea, vomiting, constipation, drowsiness, dizziness, and respiratory depression.
If patients cannot tolerate opioids, tramadol may be tried. Tramadol is a non-opioid derived synthetic opioid. It acts by binding to opioid mu receptors, in addition to inhibiting norepinephrine and serotonin reuptake. This medication carries some similar side effects to opioids, except that tramadol can lower the seizure threshold and potentiate the serotonin syndrome in combination with certain other medications, such as SNRIs and SSRIs. Tramadol carries a risk of abuse potential, but much lower than opioid analgesics. For tramadol dosing, start with 50 mg once daily or twice daily. Increase by 50–100 mg daily in divided doses, every 3–7 days, as tolerated until pain relief. Total daily dose should not exceed 400 mg daily, and in patients over 75 years old, 300 mg daily.
Tapentadol is a newer opioid analgesic which has two mechanisms of action: a mu-opioid receptor agonist as well as a norepinephrine reuptake inhibitor, similar to tramadol, but more potent. It is available in immediate and extended release formulations. The immediate release formula comes in 50, 75, and 100 mg strengths taken every 4–6 h, while the extended release is available in 50, 100, 150, 200, and 250 mg strengths, taken every 12 h. Use of tapentadol is not recommended for patients with severe renal or hepatic impairment and is contraindicated in patients with risk of seizures.
Phantom Limb Sensation
Patients should be educated and reassured that phantom limb sensation is normal. Recognizing PLS early on can help to prevent progression to phantom limb pain. Simple techniques such as light massage or tapping of the residual limb, vibration, and transcutaneous electrical nerve stimulation (TENS) can help to avoid this progression. For phantom itch, patients may try scratching the contralateral intact limb in the same location of the itching [5].
Phantom Limb Pain
Psychological Management
Working with a rehabilitation psychologist in the acute inpatient rehabilitation setting can be beneficial. The psychologist can help the patient to cope with their new self-image. Biofeedback and cognitive behavioral therapy can also be used to reduce pain. Biofeedback therapy can incorporate techniques such as progressive muscle relaxation or guided imagery, together with electromyographic (EMG) biofeedback or skin temperature feedback. Muscle relaxation techniques help to reduce muscle tension and to increase blood flow and may be efficacious in treating PLP [12]. Thermal biofeedback training is thought to help in PLP by mediating net regional sympathetic arousal. It allows an individual to monitor peripheral temperature and to thereby indirectly monitor and modify sympathetic activity. In a small study, Harden and associates demonstrated that by using thermal biofeedback, a patient can have reduction in PLP over a 4–6 -week course [12].
Rehabilitation Management: Physical and Occupational Therapies
Desensitization of the residual limb is important in the postoperative phase of rehabilitation. Limitations to desensitization might include non-removable postoperative casts or IPOP. Rubbing or massaging the residual limb is recommended for desensitization. Therapists may also apply different textures to the residual limb. Soft tissue and scar mobilization can also be performed. These techniques are initially performed by the therapist and then taught to the patient.
Physical modalities such as acupuncture, TENS, vibration, and ultrasound are thought to relieve pain through the gate control mechanism. If the non-nociceptive A-beta fibers are activated through these modalities, transmission of the nociceptive A-delta and C-fibers will be inhibited [13].
Mirror therapy has been shown to be very beneficial in helping to treat PLP. In mirror therapy, the patient looks at the reflection of their intact limb in a mirror box. This can induce sensations of movement in the phantom limb. Physiological studies have shown that both the mirror-box therapy and the motor imagery resulted in increased excitability of the corticospinal spinal pathways [14]. This partially depends on the so-called mirror neuron system, which includes neurons that are active not only during the execution of the task itself, but also during the observation of the task [15]. A controlled neuroimaging study of motor imagery in PLP resulted in a significant decrease of intensity and unpleasantness of pain, which correlated with reduction (improvement) of cortical reorganization [16].
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