Neurologic and Neurosurgical Approaches to Pain Management

Neurologic and Neurosurgical Approaches to Pain Management

In some situations, especially with long-term and severe in-tractable pain, usual pharmacologic and nonpharmacologic methods of pain relief are ineffective. In those situations, neuro-logic and neurosurgical approaches to pain management may be considered. Intractable pain refers to pain that cannot be relieved satisfactorily by the usual approaches, including medications. Such pain usually is the result of malignancy (especially of the cervix, bladder, prostate, and lower bowel), but it may occur in other conditions, such as postherpetic neuralgia, trigeminal neu-ralgia, spinal cord arachnoiditis, and uncontrollable ischemia and other forms of tissue destruction.

Neurologic and neurosurgical methods available for pain relief include (1) stimulation procedures (intermittent electrical stimulation of a tract or center to inhibit the transmission of pain impulses), (2) administration of intraspinal opioids (see pre-vious discussion), and (3) interruption of the tracts conducting the pain impulse from the periphery to cerebral integration cen-ters. The latter are destructive or ablative procedures, and their effects are permanent. Ablative procedures are used when other methods of pain relief have failed.

STIMULATION PROCEDURES

Electrical stimulation, or neuromodulation, is a method of sup-pressing pain by applying controlled low-voltage electrical pulses to the different parts of the nervous system. Electrical stimulation is thought to relieve pain by blocking painful stimuli (the gate control theory). This pain-modulating technique is administered by many modes. TENS and dorsal spinal cord stimulation are the most common types of electrical stimulation used. (See previous discussion of TENS.) In addition, there are also brain-stimulating techniques in which electrodes are implanted in the periventric-ular area of the posterior third ventricle, allowing the patient to stimulate this area to produce analgesia.

In spinal cord stimulation, a technique used for the relief of chronic, intractable pain, ischemic pain, and pain from angina, a surgically implanted device allows the patient to apply pulsed electrical stimulation to the dorsal aspect of the spinal cord to block pain impulses (Linderoth & Meyerson, 2002). (The largest accumulation of afferent fibers is found in the dorsal column of the spinal cord.) The dorsal column stimulation unit consists of a radiofrequency stimulation transmitter, a transmitter antenna, a radiofrequency receiver, and a stimulation electrode. The battery-powered transmitter and antenna are worn externally; the re-ceiver and electrode are implanted. A laminectomy is performed above the highest level of pain input, and the electrode is placed in the epidural space over the posterior column of the spinal cord. (The placement of the stimulating systems varies.) A subcutaneous pocket is constructed over the clavicular area or some other site for placement of the receiver. The two are connected by a sub-cutaneous tunnel. Careful patient selection is necessary, and not all patients receive total pain relief.

Deep brain stimulation is performed for special pain prob-lems when the patient does not respond to the usual techniques of pain control. With the patient under local anesthesia, electrodes are introduced through a burr hole in the skull and inserted into a selected site in the brain, depending on the location or type of pain. After the effectiveness of stimulation is confirmed, the im-planted electrode is connected to a radiofrequency device or pulse-generator system operated by external telemetry. It is used in neuropathic pain that may occur with damage or injury that oc-curred following stroke, brain or spinal cord injuries, or phantom limb pain. Use of deep brain stimulation has decreased and may be related to improved pain control and intraspinal therapies (Rezai & Lozano, 2002).

Interruption of Pain Pathways

As described above, stimulation of a peripheral nerve, the spinal cord, or the deep brain using minute amounts of electricity and a stimulating device is used if all other pharmacologic and non-pharmacologic treatments fail to provide adequate relief. These treatments are reversible. If they need to be discontinued, the ner-vous system continues to function. Treatments that interrupt the pain pathways, however, are permanent.

Pain-conducting fibers can be interrupted at any point from their origin to the cerebral cortex. Some part of the nervous system is destroyed, resulting in varying amounts of neurologic deficit and incapacity. In time, pain usually returns as a result of either regeneration of axonal fibers or the development of alter-native pain pathways.

Destructive procedures used to interrupt the transmission of pain include cordotomy and rhizotomy. These procedures are of-fered if the patient is thought to be near the end of life and will have an improved quality of life as an outcome (Linderoth & Meyerson, 2002). Often these procedures can provide pain relief for the duration of a patient’s life. The use of other methods to interrupt pain transmission is waning since the use of intraspinal therapies and newer pain management treatments are available.

CORDOTOMY

A cordotomy is the division of certain tracts of the spinal cord (Fig. 13-10). It may be performed percutaneously, by the open method after laminectomy, or by other techniques. Cordotomy is performed to interrupt the transmission of pain (Hodge & Christensen, 2002). Care must be taken to destroy only the sen-sation of pain, leaving motor functions intact.

RHIZOTOMY

Sensory nerve roots are destroyed where they enter the spinal cord. A lesion is made in the dorsal root to destroy neuronal dys-function and reduce nociceptive input. With the advent of micro-surgical techniques, the complications are few, with mild sensory deficits and mild weakness (Fig. 13-11).

Nursing Interventions

With each of these procedures, patients are provided with written and verbal instructions about their expected effect on pain and on possible untoward consequences. 

The patient is monitored for specific effects of each method of pain intervention, both positive and negative. The specific nursing care of patients who undergo neurologic and neurosurgical procedures for the relief of chronic pain depends on the type of procedure performed, its effectiveness in relieving the pain, and the changes in neurologic function that accompany the procedure. After the procedure, the patient’s pain level and neurologic function are assessed. Other nursing inter-ventions that may be indicated include positioning, turning and skin care, bowel and bladder management, and interventions to promote patient safety. Pain management remains an important aspect of nursing care with each of these procedures.

ALTERNATIVE THERAPIES

People suffering chronic, debilitating pain are often desperate. Often they will try anything, recommended by anyone, at any price. Information about an array of potential therapies can be found on the Internet and in the self-help section of the book-store. Therapies specifically recommended for pain from these sources include but are not limited to chelation, therapeutic touch, music therapy, herbal therapy, reflexology, magnetic ther-apy, electrotherapy, polarity therapy, acupressure, emu oil, pectin therapy, aromatherapy, homeopathy, and macrobiotic dieting. Many of these “therapies” (with the exception of macrobiotic di-eting) are probably not harmful. However, they have yet to be proven effective by the standards used to evaluate the effective-ness of medical and nursing interventions. The National Institutes of Health has established an office to examine the effectiveness of alternative therapies.

Despite the lack of scientific evidence that these therapies are effective, a patient may find any one of them helpful via theplacebo response. It is important when caring for a patient who is using or considering using untested therapies (often referred to as alternative therapies) not to diminish the patient’s hope and potential placebo response. This must be weighed against the professional nurse’s responsibility to protect the patient from costly and potentially harmful and dangerous therapies that the patient is not in a position to evaluate scientifically.

Problems arise when patients do not find relief but are de-prived of conventional therapy because the alternative therapy “should be helping,” or when patients abandon conventional therapy for alternative therapy. In addition, few alternative ther-apies are free. Desperate patients may risk financial ruin seeking alternative therapies that do not work.

The nurse’s role is to help the patient and family understand scientific research and how that differs from anecdotal evidence. Without diminishing the placebo effects the patient may receive, the nurse encourages the patient to assess the effectiveness of the therapy continually using standard pain assessment techniques. In addition, the nurse encourages the patient using alternative therapies to combine them with conventional therapies and to discuss this use with the physician.