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. 2022 Jul;26(6):1269-1281.
doi: 10.1002/ejp.1947. Epub 2022 Apr 12.

Mechanism underlying painful radiculopathy in patients with lumbar disc herniation

Gil Samuelly-Leichtag  1 , Elon Eisenberg  1   2 , Yaniv Zohar  1   3 , Maisa Andraous  4 , Ayelet Eran  1   4 , Gill E Sviri  1   5 , Ory Keynan  6
Affiliations

Mechanism underlying painful radiculopathy in patients with lumbar disc herniation

Gil Samuelly-Leichtag et al. Eur J Pain. 2022 Jul.

Abstract

Background: Painful lumbar radiculopathy is a neuropathic pain condition, commonly attributed to nerve root inflammation/compression by disc herniation. The present exploratory study searched for associations between pain intensity and inflammatory markers, herniated disc size, infection, psychological factors and pain modulation in patients with confirmed painful lumbar radiculopathy scheduled for spine surgery.

Methods: Prior to surgery, 53 patients underwent the following evaluation: pain intensity measured on a 0-10 numeric rating scale (NRS) and the Short-Form McGill Pain Questionnaire; sensory testing (modified DFNS protocol); pain processing including temporal summation and conditioned pain modulation (CPM); neurological examination; psychological assessment including Spielberger's Anxiety Inventory, Pain Sensitivity Questionnaire and the Pain Catastrophizing Scale. Pro-inflammatory cytokine levels (IL-1b, IL-6, IL-8, IL-17, TNFα, IFNg) and microbial infection (ELISA and rt-PCR) in blood and disc samples obtained during surgery. MRI scans assessments for disc herniation size/volume (MSU classification/ three-dimensional volumetric analysis).

Results: Complete data were available from 40 (75%) patients (15 female) aged 44.8 ± 16.3 years. Pain intensity (NRS) positively correlated with pain catastrophizing and CPM (r = 0.437, p = 0.006; r = 0.421, p = 0.007; respectively), but not with disc/blood cytokine levels, bacterial infection or MRI measures. CPM (p = 0.001) and gender (p = 0.029) were associated with average pain intensity (adjusted R2 = 0.443).

Conclusions: This exploratory study suggests that pain catastrophizing, CPM and gender, seem to contribute to pain intensity in patients with painful lumbar radiculopathy. The role of mechanical compression and inflammation in determining the intensity of painful radiculopathy remains obscure.

Significance of study: Pain catastrophizing, CPM and gender rather than objective measures of inflammation and imaging seem to contribute to pain in patients with painful radiculopathy.

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Conflict of interest statement

G. Samuelly‐Leichtag (PhD) reports no disclosures. E. Eisenberg (MD) reports no disclosures. Y. Zohar (MD, PhD) reports no disclosures. M. Andraous (MD) reports no disclosures. A. Eran (MD) reports no disclosures. G. Sviri (MD) reports no disclosures. O. Keynan (MD) reports no disclosures.

Figures

FIGURE 1
FIGURE 1
Flow Chart. Complete data were available from 40 (75%). Thirteen patients were excluded from the statistical analysis due to lack of MRI scans (9 patients) or additional pathology such as spinal stenosis (4 patients)
FIGURE 2
FIGURE 2
Disc tissue cytokines ΔCt. The ΔCt of each cytokine gene is shown in relation to the housekeeping gene (GAPDH). The ΔCt is the distance between the specific cytokine target gene Ct and the housekeeping gene Ct and is calculated as follows: ΔCt = Cttarget – CtGAPDH. Note that higher negative values illustrate higher concentrations of the target cytokine gene
FIGURE 3
FIGURE 3
CPM correlation with pain variables. CPM magnitude negatively correlated with average pain ratings, maximal pain ratings and with the SF‐MPQ score
FIGURE 4
FIGURE 4
PCS correlation with pain variables. PCS moderate positively correlated with average pain ratings, maximal pain ratings and with the SF‐MPQ score
See this image and copyright information in PMC

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