<p>Female Overrepresentation in Low Back-Related Leg Pain: A Retrospective Study of the Autonomic Response to a Minimally Invasive Procedure</p>

Abstract

Background The newly proposed low back pain treatment requires case classification according to the pain mechanism (nociceptive, neuropathic or nociplastic) to determine the most effective therapeutic approach. However, there is a lack of objective tools for distinguishing these pain mechanisms. The aim of the study was to identify which symptoms, signs, and standard diagnostic parameters would allow predicting the nociplastic pain (NP) subtype among low back leg pain (LBLP) patients. Methods A retrospective analysis of an LBLP case–control study database was carried out. The presence of NP was assumed if the patient presented with myofascial pain syndrome (MPS) and developed a short-term intensive vasodilatation reaction in the perceived lower leg pain area after provocation by a minimally invasive procedure. Clinical data and standard LBLP diagnostic parameters were analyzed to classify patients as NP (+) vs NP (-). Next, to predict NP probability, logistic regression analysis and a diagnostic classification tree were constructed. Results NP was confirmed in 43.75% of LBLP patients. Women represented 95.24% of all NP (+) patients. The diagnostic classification tree indicated that NP was highly probable if the LBLP subject was female and the result of a positive straight leg raise (SLR) test was lower than 45 degrees. If the SLR test result was greater than or equal to 45 degrees, a negative result on the Bragard test would have diagnostic value. This classification tree was approved to a certain extent in the logistic regression model (deviance residuals, min: −1.8519; 1Q: −0.5551; median: −0.1907; 3Q: 0.6565 and max: 2.1058) but should be verified in a larger group of subjects. Conclusion Female sex, but not clinical data or standard diagnostic parameters, is indicative of nociplastic pain in LBLP patients. More sophisticated statistical methods, based on directly measurable parameters, should be proposed to distinguish NP involvement in LBLP.

The Rationale for the Automation of a New Diagnostic Thermography Protocol to Confirm a Chronic-Low-Back-Pain Subtype Related to Nociplastic Pain

“…A similar observation has been provided by studies of a minimally invasive procedure (MIP) applied in conditions related to central sensitization [25][26][27]. The MIP provoked transient amplified vasomotor phenomenon defined as autonomic referred pain (AURP), which is a newly discovered biological reaction due to the ANS imbalance caused by the noxious stimulus applied to active trigger points [25,26]. Importantly, the AURP develops exactly in the patients' pain zone coincident with the muscle referred pain pattern proposed by Travell and Simons in their published theory of myofascial pain [13].…”

“…It has been proved that the sympathetic function is more related to stimulus intensity than perceived pain intensity. A similar observation has been provided by studies of a minimally invasive procedure (MIP) applied in conditions related to central sensitization [25][26][27]. The MIP provoked transient amplified vasomotor phenomenon defined as autonomic referred pain (AURP), which is a newly discovered biological reaction due to the ANS imbalance caused by the noxious stimulus applied to active trigger points [25,26].…”

“…Currently, there are only a few experimental studies suggesting the ANS involvement in muscle referred pain [26,27]. Those studies have documented intensive vasodilatation in the area of perceived sciatic pain provoked by a minimally invasive method applied to trigger points within gluteus minimus.…”

“…The MIP protocol is a proposal of a completely new approach in medical thermography. It is similar to ADT protocols, but it has some basic differences [25,26,29]. Generally, the MIP allows one to register pathological ANS activity, which can help characterize a certain subpopulation of pain patients.…”

The Automatization of a New Thermography Method Using Invasive Nociceptive Stimulation to Confirm an Autonomic Phenomenon within a Trigger Point Referred Pain Zone

“…The Minimally Invasive Procedure (MIP) is a new type of ADT proposed to confirm autonomic phenomenon observed within the referred pain zone due to the noxious stimulus of a trigger point. Very likely, this new proposal may be a valuable tool for an objective TrP confirmation [14].…”