Pain in the Nerves: Do you check?

Most, if not all, patients I see present with pain – pain here, pain there, pain everywhere. I guess it’s one of those realizations that hit you after being in practice for some time. However, having pain as the most common chief complaint doesn’t make work any easier. A misconception I encountered during a recent out of town trip was when a doctor approached me asking what was the best drug to use when a patient complains of musculoskeletal pain. This was not the first time I encountered this. In fact, several colleagues and some past junior residents believed that rheumatology practice hinged on knowing the best combination of analgesics to deal with pain. It’s like they believe that “if a patient complains of pain then we should automatically give….”

However, far from being that simple, the most important step  is to actually identify the source of the pain. The group is quite homogenous — pain can be further classified as nociceptive (arising from tissue damage), inflammatory (resulting from a process driven by inflammation), neuropathic (from lesions involving the nervous system) or dysfunctional (no tissue damage, no inflammation or lesions involving the nervous system but still causing significant pain – e.q. fibromyalgia). What’s more interesting is that different types of pain may co-exist in a single patient. In a patient with RA, for example, pain may arise from the inflammatory process and from the resulting joint damage. In osteoarthritis, the nociceptive pain from joint damage may at times have superimposed synovitis/ bursitis (inflammatory) or be complicated by fibromyalgia (dysfunctional). Only after identifying the pain mechanisms involved can the proper treatment then be started.

Neuropathic pain may co-exist in a lot of patients with joint pains. When a patient with spinal pain, for example, fails to respond to an analgesic, the next action to be taken by physicians is either to increase the dose further or to shift to another analgesic class. But as pointed out by one study (Poitras et al, BMC Musculoskeletal Disorders 2008), one of the clinical barriers to successful treatment of spinal pain is failure to identify the neuropathic component. For chronic spinal pain (involving either the neck, upper back and lower back), as high as 35% of patients may have neuropathic symptoms. How then do we identify patients with neuropathic pain when there are several patients waiting in your clinic? We use screening tools.

Several tools are available to screen patients for neuropathic pain. The following are just some of them.

Presentation1

Probably one of the easiest to employ is ID Pain Questionnaire which consists of 6 questions that can be self-administered by the patient.

These questions are

  1. Does the pain feel like pins and needles? (Yes = +1; No = 0)

  2. Does the pain feel hot/ burning? (Yes = +1; No = 0)

  3. Does the pain feel numb? (Yes = +1; No = 0)

  4. Does the pain feel like electric-shocks? (Yes = +1; No = 0)

  5. Is the pain made worse with the touch of clothing or bed sheets? (Yes = +1; No = 0)

  6. Is the pain limited to your joints? (Yes = –1; No = 0)

A score of at least 2 means the patient may have neuropathic pain.

The SigN-PQ is another tool worth considering since is has been validated in the local dialect by its authors.

Slide1

Slide2

If the patient answers yes to any one of the N1 pain descriptors and yes to both the N2 and N3 Questions, then the patient most likely has neuropathic pain.

 So the next time you are faced with a patient in pain not responding to initial analgesics you had prescribed, check if there is neuropathic pain involved.

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