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Simple bedside test improves diagnosis of chronic back pain, could guide treatment
A simple and inexpensive method of assessing pain developed by researchers at Massachusetts General Hospital in Boston may be better than currently used techniques for distinguishing neuropathic pain from other types of chronic back pain, according to a report in the April 7 issue of the open-access journal PLoS Medicine.
Being able to more precisely determine the underlying nature of the pain is essential to choosing the best treatment, researchers said in a press release.
“Currently, clinicians measure pain only by asking how bad it is, using scales from mild to moderate to severe, or by asking patients to rate their pain from 1 to 10,” lead investigator Joachim Scholz, MD, said in a press release. “This approach misses key characteristics that reflect the mechanisms causing the pain.”
Clifford Woolf, MD, PhD, senior investigator and director of the Neural Plasticity Research Group at Massachusetts General Hospital, added, “By evaluating individual components of pain, our method allows the creation of a ‘pain fingerprint’ for each patient.”
Neuropathy or low back pain
In order to identify specific symptoms and signs that could signify underlying pain mechanisms, the investigators enrolled a group of 187 patients with chronic pain. Some patients had neuropathy associated with diabetes or shingles, while others had low back pain with or without evidence of spinal nerve root damage, according to the press release.
These participants received an extensive medical history and physical examination, including 23 simple tests that could be conducted at the bedside or in an office visit. Distinct association patterns of pain-related symptoms and signs allowed the researchers to classify six subgroups of patients with neuropathic pain and two subgroups with non-neuropathic pain, according to the press release.
Based on a detailed analysis of these results, the research team — which also included investigators from England and Switzerland — developed the Standardized Evaluation of Pain (StEP), a set of 6 questions and 10 physical tests that best discriminated between neuropathic and non-neuropathic pain.
To determine whether or not their pain was neuropathic, patients were evaluated by an interdisciplinary team of two physicians (a neurosurgeon and a rheumatologist) and a physical therapist. Participants then received the StEP assessment from a specially trained investigator not informed of the results of the clinical evaluation.
Better than existing tests
Not only was the 10- to 15-minute StEP assessment able to accurately determine whether or not a participant's back pain was neuropathic; it was also superior to an existing screening test for neuropathic pain and even to MR imaging of the spine, which can be misleading since many people have visible degeneration of spinal discs with little or no pain, Scholz said in the press release.
“The treatment of neuropathic and non-neuropathic pain is quite different, and if a diagnosis is wrong, patients may receive treatment, including surgery, that does not improve their pain,” he said in the press release. “We showed that StEP is a valuable diagnostic tool for low back pain, and we will conduct further studies to determine the usefulness of our clinical approach in other types of pain.”
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