Chronic Pain Patients, CRPS 1 & 2

A debate is currently raging as to whether diagnoses, such as fibromyalgia and complex regional pain syndrome 1, can be classified as neuropathic. Our NPS cut-off score results suggest that these diagnoses may have a neuropathic pain component. The reliability and validity of our NPS method will need to be tested further in other neuropathic pain models, such as diabetic peripheral neuropathic pain.

Study Suggests Fibromyalgia Pain is Neuropathic

In the March issue of the journal Pain Medicine, researchers at three institutions in Florida conducted a study to determine whether the neuropathic pain scale (NPS) can be used to classify chronic pain patients (CPPs) as having primarily neuropathic vs non-neuropathic pain, as well as to determine whether there is a cut-off score that can be used reliably to make this distinction between types of pain. This study evaluated 305 chronic pain patients (CPPs) admitted to The Rosomoff Pain Center (Miami, FL). All were administered the NPS, a diagnostic tool designed to assess the distinct pain qualities associated with neuropathic pain, and were given a diagnosis on the basis of a physical examination and all available test results.

Using patients known to have neuropathic or non-neuropathic pain conditions as a reference, esearchers were able to derive "an NPS cut-off score above which CPPs would be classified as having neuropathic pain." Patients who had diagnoses of myofascial pain syndromes, spinal stenosis, epidural fibrosis, fibromyalgia, complex regional pain syndromes, and failed back surgery syndrome, a predicted NPS score was calculated and compared with the cut-off score.

The NPS appeared to be able to separate CPPs into neuropathic pain vs non-neuropathic pain subtypes. The cut-off score the researchers derived was 5.53 on the NPS. Myofascial pain syndrome and spinal stenosis had scores lower than this cut-off score at 3.81 and 4.26, respectively - Therefore they did not meet the criteria for neuropathic pain. Epidural fibrosis, fibromyalgia, complex regional pain syndromes, and failed back surgery syndrome had predictive scores higher than the cut-off score at 6.15, 6.35, 6.87, 9.34, and 7.19, respectively. Thus, these syndromes did meet the qualifications for neuropathic pain according to this study's criteria. The researchers conclude that the NPS does appear to be able to discriminate between patients experiencing neuropathic and non-neuropathic pain.

Pain Medicine, Vol. 9, No. 2. (March 2008), pp. 149-160.

David A. Fishbain MDFAPA, John E. Lewis PhD, Robert Cutler PhD, Brandly Cole PsyD, Hubert L. Rosomoff MDDMedScFAAPM, Rennée S. Rosomoff BSNMBA (2008)
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1526-4637.2007.00302.x