Peripheral Neuropathy e-Support

Here is a synopsis of Dr. Wolfe's article, composed by Jo Nell Wilder. If you would like to see a PDF format version of the whole article click here.

Painful Peripheral Neuropathy

Gil I.Wolfe, MD*
Richard J. Barohn, MD
Address
*Department of Neurology
University of Texas Southwestern Medical Center
5323 Harry Hines Boulevard
Dallas, TX 75390-8897, USA.
E-mail: gil.wolfe@utsouthwestern.edu
Current Treatment Options in Neurology 2002, 4:177­188
Current Science Inc. ISSN 1092-8480
Copyright © 2002 by Current Science Inc.

Primary care physicians, neurologists, and other specialists commonly encounter peripheral neuropathies associated with neuropathic pain. It has been estimated that neuropathic pain affects at least 2% of the US population. Painful peripheral neuropathies can be challenging to evaluate and treat. The cause of the peripheral neuropathy may remain unknown in a majority of patients, the so called idiopathic or cryptogenic sensory polyneuropathies. The inability to identify a specific etiology for the neuropathy can be frustrating for both patients and their clinicians. Of identifiable etiologies, diabetes and alcohol abuse are the most common, but there are a large number of other causes (Table 1).

Opinion statement

• Treatment of neuropathic pain is the primary focus of management for many patients with painful peripheral neuropathies. Neuropathic pain is a common feature of many peripheral neuropathies including those associated with diabetes, uremia, HIV infection, and alcohol abuse. Pain is also present in the majority of patients with idiopathic sensory and sensorimotor polyneuropathies.
• A growing number of pharmacologic agents are available for the treatment of neuropathic pain. The medications that have undergone the most rigorous study are the tricyclic antidepressants and anticonvulsants. These two families of medications are widely used and represent first-line agents in the management of neuropathic pain.
• Pain management should begin with a concerted effort to identify the etiology of the neuropathy, as directed therapy may help alleviate the symptoms. When initiating pharmacotherapy for neuropathic pain, one must individualize treatment and choose an agent that is likely to be tolerated, as adverse events are not uncommon for some of the medications. Treatment of neuropathic pain remains challenging, with considerable variability in an individual's response to the various agents and even to different drugs in the same class. However, monotherapy with a well-chosen agent or rational polypharmacy that combines medications with different mechanisms of action will benefit a majority of patients with neuropathic pain.

Treatment

• Avoid excessive alcohol intake. In general, patients with neuropathy should limit consumption to one serving of alcohol daily. If the neuropathy is related to alcohol abuse, abstinence should be stressed.
• Maintain a balanced diet. Patients with diabetes should follow appropriate American Diabetes Association guidelines.
• Encourage the development of coping skills, stress management, relaxation techniques, and biofeedback.
• Multivitamin supplementation can be considered, especially in patients with neuropathy related to alcohol abuse. However, overuse of pyridoxine (more than 200 mg per day) should be avoided.

Topical agents

Capsaicin Capsaicin, an alkaloid extracted from chili peppers that depletes substance P from sensory nerves, has had a significant effect on neuropathic pain in a majority of studies of diabetic neuropathy. a positive effect for capsaicin.

Standard dosage 0.075% capsaicin cream is applied to the painful area three to four times daily. Contraindications Prior hypersensitivity to topical application or to hot peppers. Main drug interactions No significant interactions for topical use. Main side effects Transient burning, sneezing, coughing, and skin irritation and rash. Special points Capsaicin cream is available over-the-counter. The cream should be used in well ventilated areas, and patients should avoid rubbing their eyes after use. Nonsteroidal anti-inflammatory agents may be added if the initial burning from capsaicin is intense. This side effect usually improves over several weeks.

• There are a wide variety of interventional therapies for painful peripheral neuropathy. In general, these approaches are reserved for patients who have failed a number of aggressive trials using oral or topical agents. Interventional techniques include local anesthetic blocks, acupuncture, percutaneous as well as implanted spinal cord stimulators, and implanted intrathecal catheters for delivery of opiates, local anesthetics, and antispasticity agents.
• Interventional therapies are best performed by physicians with specialized skill who are familiar with and are able to manage potentially serious adverse events, which can include respiratory depression and apnea from intrathecal drug delivery. These techniques are mainly available through anesthesiologist-staffed pain clinics.

Special points Percutaneous electrical nerve stimulation has decreased the daily oral analgesic requirements in a number of chronic pain states. Based on current studies, it should be viewed as an adjunctive, and not primary, therapy.

Transcutaneous stimulation
Transcutaneous electrical stimulation (TENS) is widely used in neuromuscular and pain syndromes, although its efficacy is actively debated. Response to this noninvasive technique varies significantly between studies and patients.

Standard procedure Treatment with TENS units generally begins daily, with stimulation sessions lasting 30 minutes or longer. Over time, one can reduce the frequency of treatment sessions, although the analgesic effect is transient, and the procedure needs to be repeated at least every few weeks. Contraindications None. Complications Essentially none. Some patients find it difficult to tolerate the surface stimulation due to allodynia. Special points Individual adjustments of the pulse waveform, duration, frequency, and voltage are required to maximize the clinical response.

Magnetic therapy
Annual worldwide spending for magnetic devices to treat pain is estimated to be in the billions of dollars. Public acceptance of subthreshold magnetic devices is largely based on anecdotal statements, although rigorous trials are now being performed to test this alternative approach. A preliminary randomized, sham-controlled crossover study of magnetic insoles in peripheral neuropathic pain provides some basis for efficacy. However, the study was small, diabetic patients responded far better than non-diabetics, and no group was ever assigned to sham magnets for both feet at the same time, complicating the analysis. Results from a larger, double blinded, placebo-controlled study of magnetic insoles in diabetic neuropathy are pending.

Complications Essentially none. The uneven surface of some magnetic insoles may place neuropathy patients with foot ulceration or sores at risk

• · Physical therapy and exercise may indirectly benefit patients with neuropathic pain. Muscle function and cardiovascular fitness can improve. Improving a patient's overall condition and well-being may enhance pain management efforts.
• · Exercise is a key component of most weight-loss programs, an important factor for diabetics in controlling hyperglycemia.

Neuromuscular Disorders

• Physical therapy programs may include relaxation and stretching techniques that are beneficial.

Contacts

E-Mail Support, Jo Nell Wilder at tcjennin@earthlink.net

WebMaster, Dwain Wilder dwain@bearmeadow.com

We extend our appreciation to the Neuropathy Association in New York City (1-800-247-6968) for their help in getting our Support Group organized, and to all the volunteers who helped with their expertise.

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