WHEN PAIN is neuropathic in origin, patients may struggle to describe it accurately. Most patients describe surgical pain or acute pain from injury as aching or sharp, but patients with neuropathic pain use descriptors such as burning, painful tingling, or shooting.
Because assessing pain having a neuropathic source is difficult, these conditions can end up being treated like nonneuropathic pain, providing less-than-optimal outcomes. Consider the following case studies.
Case study 1. Ms. S, 46, had a radical mastectomy for breast cancer 6 months ago. She's a legal secretary who works on a computer. When she returns to work after her surgery, the limited mobility of her surgical shoulder begins to give her difficulty. She reports continued pain in her shoulder and great difficulty raising her arm. When asked about her pain, she replies, "My surgical pain is gone, but I'm having odd prickling and shooting sensations through my armpit. The pain is about a 7 out of 10. The pain just comes and goes without any warning and makes doing my mobility exercises much more difficult. When I take pain medication to help me move my arm, it not only doesn't help, but it makes me sleepy. These feelings also wake me up at night. I've stopped telling my healthcare providers about the sensations because the medications they've given me don't help."
Ms. S is motivated to recover so she can function better at her job. Although her surgical pain is gone, she's significantly limited by prickling and shooting pain in the surgical area. What type of pain is she experiencing and why don't her pain medications work?
Case study 2. Mr. B, 54, who had an above-the-knee amputation, has returned to your clinic after his rehab. When you ask him about pain, he tells you, "I don't like to talk about it much because I don't want people to think I'm crazy. The foot that was amputated feels as if it's located just at my knee. Isn't that strange? I have some burning pain like the neuropathy that I had before my surgery. What do you think is making my leg feel like that? It makes putting on my prosthesis difficult because I feel like I'm squeezing the foot that's not really there. Not being able to tolerate my new leg is holding me back. I really don't know how to manage the discomfort and these strange sensations."
Both of these patients have neuropathic pain. Ms. S's pain results from her surgery; Mr. B's pain results from his diabetes and surgery. Because this type of pain is difficult to assess and manage, many patients stop talking about the pain. They feel it won't get any better and don't want to be seen as complainers.
For nurses caring for patients with diseases such as diabetes and peripheral arterial disease, traumatic or postsurgical neuropathies, or chemotherapy-induced neuropathies, listening to them describe their pain is key to differentiating it from a nociceptive pain. If the patient uses descriptors such as burning, tingling, pinpricking sensations, painful tingling, or shooting, the pain most likely has a neuropathic origin. Standard pain medications such as opioids aren't fully effective for this pain. Neuropathic pain requires a comprehensive and multimodal approach to get the best patient outcome.
Some patients with chemotherapy-induced peripheral neuropathy or diabetic peripheral neuropathy describe their feet as numb. This numbness can lead to undetected injuries, fractures, or pressure ulcers. Teach these patients to regularly inspect their feet for injuries or skin breakdown.
Tackling neuropathic pain
Recently, the International Association for the Study of Pain developed new guidelines for assessing neuropathic pain. These guidelines highlight the best definition of this type of pain and some practice recommendations for screening and diagnosis.
Nociceptive pain, such as pain from an injury or surgery, is a direct result of tissue injury. In the past, neuropathic pain was defined as "pain initiated from a lesion or dysfunction in either the central or peripheral nervous system that disrupts impulse transmission and modulation of sensory input."1 The current definition, which replaces dysfunction with disease, states, "neuropathic pain is pain arising as a direct consequence of a lesion or disease affecting the somatosensory system."2 This new definition includes the idea of a neural lesion but also better defines the neuropathic origin of the pain as arising from a disease rather than a neuroplasticity of nerves, which occurs when continuous pain impulses cause nerves to change and respond faster to pain impulses. It also allows for a tighter definition of what types of pain are considered to be neuropathic, disallowing spasticity caused by lesions in the central nervous system.2
These changes may not be as important for a clinician as they are for a researcher or pain specialist, but the guidelines do clarify the source of the neuropathic pain and what aspects of the pain activation process are involved in production of neuropathic pain.
The patients presented in the case studies are experiencing pain from very different sources. Ms. S is experiencing postmastectomy pain syndrome from nerve damage that occurred during mastectomy; Mr. B is experiencing phantom limb pain from nerve damage that occurred during amputation. He also has a history of diabetic peripheral neuropathy, which may contribute to his neuropathic pain.
Management options
Ms. S and Mr. B indicate that the opioid medications they're taking are causing adverse reactions they don't like, such as sleepiness, and provide less-than-optimal pain relief. Opioids aren't indicated as first-line options for neuropathic pain relief. A stepwise approach to neuropathic pain management has been developed that helps healthcare providers determine what medication to try first and then how to add medications for added relief.3 It has four levels or steps.
1. Assessment of the patient's pain and establishment of a diagnosis of neuropathic pain. Using an assessment tool such as the recently revised McGill Pain Questionnaire can help differentiate nociceptive pain from pain with a neuropathic source.4 Comorbidities such as diabetes are identified that can complicate drug selection. The condition is discussed with the patient and realistic expectations are established.
2. Initiation of treatment. One or more of the following first-line medications is used: a secondary amine tricyclic antidepressant (such as nortriptyline or desipramine) or a selective serotonin-norepinephrine reuptake inhibitor (such as duloxetine or venlafaxine), a calcium channel alpha-2 sigma ligand (either gabapentin or pregabalin), topical lidocaine if the neuropathy and allodynia are localized, and nonpharmacologic options as appropriate.
3. Frequent reassessment of pain, adverse reactions, and function. Treatment is continued with satisfactory response, that is, pain reduced to 3 or less on a scale of 1-to-10. If the patient experiences only partial pain relief (4 or greater on a scale of 1-to-10) and tolerable adverse reactions, add another first-line medication. If no pain relief occurs or if adverse reactions are intolerable, the patient should be switched to another first-line medication.
4. If first-line medications fail when used alone or in combination, second-line medications (such as opioid analgesics or tramadol) and third-line medications (such as antiepileptics, antidepressants, or mexiletine, N-methyl-D-aspartate receptor antagonists, and topical capsaicin) as well as a referral to a pain specialist should be considered.5
Medication choices for neuropathic pain are based on trial and error. Some believe that if the patient is depressed, trying an antidepressant can help with depression as well as the pain. No matter what medication is used, if pain control is improved, the patient's mood may improve as well.
Some patients like Ms. S and Mr. B stop talking about their pain because they don't want to complain, the treatments haven't been effective, or they're more focused on recovering from the original disease. No matter what the reason, you can help patients with neuropathic pain feel that you're interested in their pain and are willing to listen. Helping patients with neuropathic pain learn to describe their pain and treating the pain using the stepwise approach can help these patients have the best outcomes and improve their quality of life.
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