Pain 2003

PAIN IS a disabling symptom. Research into its causes as well as therapies for its control remain imperfect. Chronic pain affects more than 86 million Americans and is estimated to cost $90 billion annually in reduced employment, medication expenses, and medical care.¹ Clearly, progress is being made regarding the basic, fundamental physiological mechanisms responsible for pain production and the introduction in recent years of new therapeutic approaches for the treatment of neuropathic pain. In this issue of the ARCHIVES, Dworkin et al² review new knowledge in pain diagnosis, mechanism of pain production, and treatment recommendations for neuropathic pain. Giller³ brings us up to date on the neurosurgical treatment of pain. As they point out, significant relief from chronic neuropathic pain is now both feasible and achievable, as shown by evidence-based treatment approaches with randomized controlled clinical trials.

First-line medications for chronic neuropathic pain include gabapentin, the 5% lidocaine patch, opioid analgesics, tramadol hydrochloride, and tricyclic antidepressants. Dworkin et al² review the clinical circumstances in which each of these therapeutic approaches is recommended as an initial treatment for neuropathic pain. The message is positive and optimistic.

The US Food and Drug Administration has approved both gabapentin and the 5% lidocaine patch for the treatment of postherpetic neuralgia. Opioid analgesics are also effective for treating postherpetic neuralgia as well as painful diabetic neuropathy. Tramadol, a norepinephrine and serotonin reuptake inhibitor with a major metabolite that is a µ opioid agonist, was effective in reducing neuropathic pain in patients with diabetic neuropathy and other forms of polyneuropathy. Similarly, tricyclic antidepressants are effective in treating neuropathic pain.²

When first- and second-line medications prove ineffective, the neurosurgical treatment of pain is the next option. As Giller points out in his review, "The referral of a patient to a neurosurgeon for pain relief was once considered bad news, because the choice of procedures was limited to the creation of lesions offering significant risk and only modest success."³ The neurosurgical treatment of pain has changed dramatically in recent years as a result of advances in technology; a recent definitive textbook discusses more than 30 types of procedures used in more than 18 major categories of pain.³ Giller's review is well focused and cogent. The most successful ablative neurosurgical treatments for pain include cordotomy, dorsal root entry zone lesions, sympathectomy, myelotomy, mesencephalotomy, and cingulotomy. Stimulation procedures for pain include spinal cord, motor cortex, and deep brain stimulation. Delivery of intraspinal medication, particularly for pain related to cancer, has also been effective. Other serious pain syndromes respond to intraspinal morphine delivery or morphine combined with bupivacaine hydrochloride or lidocaine.

No patient should have to bear unremitting, serious chronic neuropathic pain. According to Dworkin et al² and Giller,³ pharmacologic and neurosurgical therapies for pain are effective and safe. Understanding the basic neurophysiologic systems responsible for pain generation is now the central issue. From this enhanced understanding will come truly effective analgesic therapies that produce minimal adverse effects, have no addictive qualities, and are cost-effective.