Distinguishing Neuropathic, Non-Neuropathic, and Mixed Pain
In the pain management community, we are all too familiar with the statistic estimating that there are 100 million adults suffering from chronic pain in the United States.1 However, with all of the recent negative attention on pain management, insufficient energy and attention have been focused on perhaps one of the more daunting aspects of chronic pain—the actual assessment and treatment of the person in pain. Therefore, it is reasonable to acknowledge that managing chronic pain in today’s healthcare system, as we come to understand more and more the complexity of pain, is challenging, but also quite rewarding.
It has become increasingly clear that chronic pain does not refer to one disorder or underlying mechanism and cannot be assessed or treated with a one-size-fits-all approach. Advances in our understanding have led to new, more effective patient assessment and treatment strategies.2,3 We expect that practitioner adoption of these types of tools may better guide and inform optimal chronic pain management, leading to better quality of life for patients. However, considerably more work needs to be done to implement truly individualized approaches to patient care with regard to pain management.
Among the most difficult aspects of treating a person in pain is identifying the type(s) and mechanism(s) of pain. Our patients often present to us experiencing more than 1 type of chronic pain, with more than 1 mechanism underlying their complaints. Assessing which mechanisms of pain a person is experiencing—in other words, assessing a patient’s pain profile—is not simple, but it is vital.
There are at least 2 important components of assessing the pain complaint(s):
- Intensity, quality, and change over time
- Differentiation among the mechanisms of ongoing pain, including those resulting in neuropathic and/or non-neuropathic pain.
To most accurately and effectively identify and understand the type of pain a person is experiencing, a multidimensional assessment covering both these components is imperative.
However, differentiation among pain types, as well as the root causes of the pain, can be difficult to ascertain using in-office tests. It is unlikely that functional magnetic resonance imaging (fMRI), or other similar tests, in the absence of detailed history-taking, would be sufficient to fully assess pain appropriately. Although there are many tests available, they seldom result in a specific diagnosis of a patient’s pain and may provide confounding results.
New resources are being developed to assist in the assessment of pain, including screening tools, such as the painDETECT questionnaire,4 which has been validated to detect neuropathic components of lower back pain. In the absence of specific tests, however, practitioners can still assess a patient by asking how he/she would describe the way the pain feels. For example, asking if there is any of the following symptoms: numbness, burning, tingling, or feelings of electric shock, which can provide useful insights. Notably, distinguishing between neuropathic and nonneuropathic pain types, and understanding if a person has features of both, can better allow for a more tailored treatment.
The Best Pain Management Comes From a Thorough Pain Assessment
When conducting a pain assessment, the evaluation should be as in-depth as possible to plan the most appropriate management course. When a patient with an established pain diagnosis(es) presents for chronic pain treatment, it is important to begin by assessing the patient’s functional impairment, expectations, and psychosocial needs, as well as to evaluate for any medical red flags, such as the risk of medication misuse or abuse.
Questions to consider asking include:
- Has the patient been treated for cancer, or is he/she being treated for some potentially unrelated condition that may contribute to the pain?
- What other medical/interventional/non-medical treatment is the patient receiving?
- What treatments have been unsuccessful in the past?
- What is the intensity and duration of the pain?
- Is the patient experiencing distress or impairments associated with chronic pain?
When considering the responses to determine a course of treatment, be mindful that multimodal therapy may be required for optimal care. Since there are various potential origins for the pain that present with similar symptom profiles and distinct mechanisms that drive pain, devising a personalized treatment may be hard to come by, but still must be our ultimate goal.
Ideally, the selection of appropriate medication to address chronic pain complaints should follow the same principle as choosing an antibiotic treatment regimen, although the complexity of chronic pain and our current knowledge do not allow for this approach in all instances. For example, there are dozens of antibiotics that can be prescribed to treat a bacterial infection. Rather than a trial-and-error approach, treatment for a bacterial infection is specifically tailored to the illness based on the culture of the bacteria and the specific manifestation of the disease. Selecting the appropriate pain medication should be treated in the same manner, whenever possible.
Consider Pain Mechanisms in Prescribing Medications
Besides analgesia and depending on severity, chronic pain can be managed in many ways, including appropriate physical therapy, cognitive-behavioral approaches, neurostimulation, acupuncture, functional medicine, and other noninvasive approaches, nonanalgesic medications, and other modalities.
Medications may include commonly used analgesics, such as aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs); for more severe pain, opioids may be more effective. So-called adjuvant analgesics (eg, anticonvulsants or antidepressants) may also be considered.
However, there may be individual differences in response to these drugs, depending on the patient’s neuropathic and non-neuropathic pain profile. Nociceptive pain, a type of non-neuropathic pain, is generally more responsive to anti-inflammatory agents and classical opioids, while neuropathic pain may be less responsive to traditional pain management. In some cases, pharmacologic agents that address more than 1 type of pain may be more effective for some patients, and many newer medicines are designed to target both types of pain in a single pill.
As we continue to gain insight into pain mechanisms and subtypes and begin to develop increasingly sophisticated evaluation tools, the need for both a thorough assessment and individualized treatment has become more evident. Preferably, pain management will begin with a rigorous evaluation, using the latest available tools, followed by evidence-based, individualized treatment with multimodal therapy where appropriate. Bringing these crucial pieces together to improve management of chronic pain will ultimately help improve patients’ lives, which is, of course, our end goal.