Chronic pain: nonpharmacologic therapy (Proceedings)

Our patient population has changed fairly dramatically in the last 10 years as our medical skills have progressed and we have become capable of supporting patients with advanced disease and advancing age. With this new set of patients comes a new set of problems, like chronic pain. Also, our surgical skills have improved and surgery now is often complicated, long, and may involve major tissue manipulation - and more severe pain than the standard 'routine elective' procedure. Thus, our ability to deal with pain, whether acute or chronic pain, must improve along with our medical and surgical skills in order to provide quality - not just quantity - of life for our patients.

When possible, multimodal therapy that includes both pharmacologic and non-pharmacologic modalities should be used to treat pain, regardless of whether the pain is acute or chronic. Pharmacologic classes that should be considered include opioids, NSAIDs, local anesthetics, NMDA-receptor antagonists, alpha-2 agonists, etc... Non-pharmacologic modalities include thermotherapy, massage, therapeutic exercises, aquatic therapy, acupuncture, electrical stimulation, therapeutic ultrasound, extracorporeal shock wave therapy, low-level laser, etc... Many of these modalities provide direct pain relief (eg, acupuncture) where others are associated with pain relief secondary to improved function and strength (eg, many therapeutic exercises).

Examples of non-pharmacologic modalities for treatment of pain:

     • Thermotherapy includes the use of both heat and cold for treatment of pain, injuries, surgical incisions, etc... Superficial heat causes increased muscle blood flow, muscle relaxation and increased extensibility of fibrous tissues.1 Superficial heat can be provided by hot packs or infrared heat lamps.1 Hot packs should be wrapped in towels and heat from all sources should be monitored carefully to avoid skin burns.1 Heat can also be provided as part of aquatic therapy when warm water is used. If stretching and range of motion exercises are to be included in the therapy, they should be performed during or immediately after the heat application since heat dissipates rapidly after removal of the heat source.1 Cryotherapy causes vasoconstriction and counteracts inflammation, provides analgesia and reduces muscle spasms.1 Cryotherapy can be provided using ice or cold packs and is ideal for reducing inflammation following surgery or exercise.1 Thermotherapy is generally fairly easy and is clearly inexpensive. Thus, this therapy should be incorporated into protocols in our hospitals and can be taught to the patient's caregiver for at-home therapy.

     • Massage decreases pain and accelerates recovery by relieving muscle tension, increasing blood flow to the painful muscles and mobilizing adhesions.1 Massage techniques include stroking, kneading, rubbing, circular pressure, shaking and percussion.1 Effects of / indications for massage include relief of muscle tension secondary to spinal or joint disease, improvement of joint and muscle function, reduction or prevention of venous stasis and lymphostasis, mobilization of adhesions, regulation of muscle tone, preparation of muscles for physical training, and acceleration of muscle recovery after training. Although advanced massage techniques should be performed by trained personnel, some techniques can be utilized in-hospital with minimal training and some can even be taught to care-givers so that the patient's massage can continue at home. Stroking, kneading and shaking are appropriate for home therapy.1

     • Therapeutic exercises are a part of physical therapy that are designed to improve active pain-free range of motion and flexibility, improve use of limbs and reduce lameness, improve muscle mass and muscle strength, improve daily function, and help prevent further injury.1 Forms of therapeutic exercises include passive exercises, proprioceptive training exercises, active exercises to improve limb use, and speed and strengthening exercises. Although some of the exercises require advanced training and/or specialized facilities, many of these can be done in-hospital with minimal training and some can be done at home following appropriate training for the care-giver. For instance, owners can use passive range of motion for post-operative cranial cruciate ligament (CCL) repair and stretching for patients with chronic joint pathology and stiffness. Other appropriate exercises for at-home treatment include elicitation of flexor reflexes, bicycling movements in lateral recumbency or in a standing position, sit-to-stand exercises, weight-shifting and leash walks.1

     • Aquatic therapy, like underwater treadmill exercises and swimming, may be used for rehabilitation after orthopedic surgery, rehabilitation after neurological injury for muscle strengthening and for improved joint function.1 Water is an excellent media for therapy because the body bears less weight in water, which reduces the load on painful joints and allows the patient to exercise more comfortably and to do exercises that were not possible for the patient on land.1 Furthermore, water pressure can reduce swelling and edema.1 However, water also produces pressure on the thorax and requires physical exertion so patients need do be evaluated for cardiovascular and pulmonary health. Aquatic therapy is not appropriate for patients with some skin conditions, open wounds or surgical incisions. Swimming, and some underwater exercises (eg, walking, bicycling and weight shifting), can often be done at home.

     • Electrical stimulation is useful for treating various orthopedic and neurological diseases, especially those causing acute and chronic pain, or muscle atrophy.1 Indications include pain management (especially in arthritis, spondylosis, spondylarthrosis, recovery from orthopedic surgery, and nerve regeneration), facilitation of fracture healing, relief of muscle tension, prevention of muscle atrophy from disuse, and muscle strengthening.1 Treatment modalities include neuromuscular electrical stimulation (NMES), transcutaneous electrical stimulation (TENS) and electrical muscle stimulation (EMS).1 Although these modalities provide a variety of frequencies and currents, low-frequency pulsed alternating currents are most commonly used for therapy.1. All forms of electrical stimulation are appropriate for in-hospital use and some forms are appropriate for home use.

     • Acupuncture has been used for thousands of years to treat pain and yet the mechanism of action is still not completely understood. The pain-relieving effect has been attributed to the activation of A-delta and possibly C fibers and the release of endogenous opioids (naloxone can often reverse acupuncture-induced analgesia). Serotonergic and adrenergic systems may also be involved. Acupuncture is used for a variety of pain syndromes including the relief of postoperative pain (eg, following CCL repair), pain from neurologic disorders (eg, following herniated disc) and pain from musculoskeletal disorders (eg, osteoarthritis). The efficacy of acupuncture in relieving pain, especially chronic pain, is documented in the veterinary literature and many veterinarians support its use. Although acupuncture should be performed by trained personnel, acupressure points can be used by the patient's caregiver at home. For more information on acupuncture, see references 2, 3 and 4.

     • Therapeutic ultrasound has numerous applications but seems to be especially effective in treating diseased and dysfunctional joints and joint components and certain muscle diseases.1 The goals of treatment are to reduce pain, improve the elasticity of fibrous structures, increase blood flow, and improve tissue nutrition.1

     • Indications for extracorporeal shock wave therapy (ESWT) include joint disease (eg, arthritis of the hip, knee or elbow) and tendinopathies.1

     • Low-level laser therapy has many possible applications, including pain relief.5

Summary

While mild pain, like the pain associated with muscle soreness following strenuous exercise, can often be controlled with non-pharmacologic therapy alone, moderate to severe pain, like the pain that occurs following surgery (acute) or in association with advanced osteoarthritis or cancer (chronic), should be controlled using multimodal therapy that includes both pharmacologic and non-pharmacologic modalities. The use of a combination of pharmacologic and non-pharmacologic therapies in combination is well-documented in human literature and should be applied more frequently to veterinary patients. For instance, recovery from joint surgery in human medicine generally includes NSAIDs to reduce the inflammation, opioids to provide analgesia and make the patient comfortable enough to exercise, ice-packs to further reduce inflammation, and range of motion and weight bearing exercises to improve joint function. Human patients with severe osteoarthritis or cancer often receive analgesic and anti-inflammatory drugs along with acupuncture and / or massage therapy. These are all modalities that could easily be implemented both in-hospital and at home for our own patients and these are all modalities that should be considered as our patients age, fight chronic disease and/or undergo highly invasive surgical procedures. The level of pain that our patients experience is steadily increasing as our medical and surgical skills increase and we must widen our analgesic capabilities in order to provide quality - not just quantity - of life for our patients.

References and further reading:

Bockstahler B, Levine D, Millis D (2004) Essential Facts of Physiotherapy in dogs and cats: Rehabilitation and pain management. BE VetVerlag, Germany.

Schoen AM (2001) Veterinary Acupuncture, Ancient art to modern medicine, 2nd ed. Mosby, St. Louis, MO.

Schwartz C (1996) Four paws, five directions, A guide to Chinese medicine for cats and dogs. Celestial Arts, Berkeley, CA.

Gaynor JS, Muir WW (2002) Veterinary Pain Management. Mosby, St. Louis.

Shearer TS (2004) High-Tech Pain Management for Pets. Ohio Distinctive Publishing, Columbus, OH.