EK HEALTH

by Richard Thompson, MD
EK Health Services' Chief Medical Officer

The term neuropathic pain (NP) is often used when referring to chronic pain. It is best understood by realizing that nerves are like electric wires; they help messages travel to and from the brain. So, the injury causing NP isn’t always something that can be seen with the eyes. Examples of NP include: diabetes, multiple sclerosis, alcoholism, shingles, an amputation causing phantom limb pain, cancer, to name just a few definitive causes. Usually, however, the exact cause of NP is poorly understood and often hard to diagnose, hard to treat, and for the patient it is hard to sleep, hard to work, and hard to function. It presents in many different ways and can cause pain, numbness, tingling, burning, and “pins and needles.”

The other kind of pain, nociceptive, is much easier to recognize. It is caused by tissue injury such as lacerations, fractures, trauma, bee stings, burns, etc. This pain hurts at the site of the wound.

MEDICATION TREATMENT of NEUROPATHIC PAIN

There is a lack of expert consensus on the treatment of neuropathic pain in general due to heterogeneous etiologies, symptoms, physical signs and mechanisms. Patients with NP are challenging to treat, challenging to manage, and must be evaluated frequently for level of function and quality of life. Although there are many alternatives to the medication management of NP, per California Medical Treatment Utilization Schedule (MTUS), the following drugs may be effective in treating NP:

• Antidepressants, including Wellbutrin®, Cymbalta® and Effexor®, especially if pain is accompanied by insomnia, anxiety, or depression
• Antiepileptic drugs, including Neurontin® and Gabarone™ have been shown to be effective for treatment of diabetic painful neuropathy and postherpetic neuralgia and have been considered as a first-line treatment for neuropathic pain.
• Antiepileptic drugs, including Keppra®, Zonegran®, and Gabitril®, may be effective for neuropathic pain. These agents should be used to treat neuropathic pain only when carbamazepine (Tegretol®), gabapentin (Neurotin®), or lamotrigine (Lamictal®) cannot be used or are ineffective.
• Capsaicin, topical, is recommended only as an option in patients who have not responded or are intolerant to other treatments.
• Baclofen has been noted to have benefits for treating lancinating, paroxysmal neuropathic pain (trigeminal neuralgia, non-FDA approved).
• Topical lidocaine is recommended for localized peripheral pain after there has been evidence of a trial of first-line therapy (anti-depressants or an AED such as gabapentin or Lyrica). Analgesic treatment should begin with acetaminophen, aspirin, and NSAIDs.
• NSAIDs may be recommended with appropriate precautions for GI symptoms & cardiovascular risk.
• Opioids may be used for moderate to moderately severe pain but are considered a second-line treatment for several reasons: (1) head-to-head comparisons have found that opioids produce more side effects than tricyclic antidepressants and gabapentin; (2) long-term safety has not been systematically studied; (3) long-term use may result in immunological and endocrine problems (including hypogonadism); (4) treatment may be associated with hyperalgesia; & (5) opioid use is associated with misuse/abuse.
• Salicylate topicals are recommended. Topical salicylate (e.g., Ben-Gay, methyl salicylate) is significantly better than placebo in chronic pain.
• Topical analgesics are primarily recommended for neuropathic pain when trials of antidepressants and anticonvulsants have failed.

MEDICATION TREATMENT of NEUROPATHIC PAIN, NOT RECOMMENDED

• Benzodiazepines are not recommended due to rapid development of tolerance and dependence. Their long term use is not recommended because their efficacy for long-term use is unproven. Most guidelines limit their use to 4 weeks.
• Topical NSAIDS are not recommended for NP as there is no evidence to support use.
• Medical marijuana for neuropathic pain must be used with caution especially in instances in which learning and memory are integral to a patient's work and lifestyle.