Researchers have devised a simple “bedside” test to distinguish between pain from nerve damage and other causes of pain. The test could lead to more accurate diagnosis and treatment for a musculoskeletal disorder (MSD) that plagues many workplaces – back pain. It is the most commonly cited reason for being absent from work.
 
The ability to determine the underlying nature of the pain more accurately is essential to choosing the best treatment, according to the researchers. It also points the way to more targeted management of the condition: just as workspaces and tasks can be modified ergonomically to help prevent certain MSDs, they can be modified to help prevent the aggravation of existing conditions.
  
The method, developed by Massachusetts General Hospital (MGH) researchers and announced in an MGH news release on April 6, is reported to be more accurate than techniques in current use for distinguishing neuropathic pain – caused by damage to the nervous system – from other types of chronic back pain.
 
The report appears in the April 7 issue of the open-access journal PLoS Medicinej, making the assessment broadly available to clinicians.

"Currently clinicians measure pain only by asking how bad it is, using scales from mild to moderate to severe, or asking patients to rate their pain from 1 to 10," said the lead author of the study, Joachim Scholz, MD, of the Neural Plasticity Research Group in the MGH Department of Anesthesia and Critical Care. "This approach misses key characteristics that reflect the mechanisms causing the pain."
 
One-hundred-and-eighty-seven patients with chronic pain caused by a known condition were enrolled in the study. Some had neuropathy associated with diabetes or shingles, and others had low back pain, with or without evidence of spinal nerve root damage. 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 classification of six subgroups of patients with neuropathic pain and two subgroups with non-neuropathic pain.
 
Based on a detailed analysis of these results, the team developed the Standardized Evaluation of Pain (StEP) - a set of six questions and 10 physical tests that best discriminated between neuropathic and nonneuropathic pain. To test the validity of StEP, they collaborated with researchers from Addenbrooke's Hospital, a teaching hospital of the University of Cambridge in England, who studied 137 patients with chronic low back pain.
 
The researchers reported that the 10- to 15-minute StEP assessment accurately determined whether a participant's back pain was neuropathic. It was also shown to be 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 disks with little or no pain.
 
Scholz explains, "The treatment of neuropathic and nonneuropathic pain is quite different, and if a diagnosis is wrong, patients may receive treatment, including surgery, that does not improve their pain.”
 
Source: Massachusetts General Hospital