Abstract
PurposeTo study the interaction between Modic changes (MC) and inflammation by macrophages in the disc, in relation to clinical symptoms before and after discectomy for lumbar disc herniation.MethodsDisc tissue was embedded in paraffin and stained with haematoxylin and CD68. Subsequently, tissue samples were categorized for degree of inflammation. Type of MC was scored on MRI at baseline. Roland Disability Questionnaire (RDQ) score and visual analogue scale for back pain and leg pain separately were considered at baseline and 1-year follow-up post-surgery. Main and interaction effects of MC and inflammation were tested against clinical outcome questionnaires. In addition, this analysis was repeated in bulging and extruded discs separately.ResultsDisc material and MRI’s of 119 patients were retrieved and analysed. Forty-eight patients demonstrated mild inflammation, 45 showed moderate inflammation, and 26 showed considerable inflammation. In total, 49 out of 119 patients demonstrated MC. Grade of disc inflammation did not associate with the presence of MC. At baseline, no main or interaction effects of MC and inflammation were found on the clinical scores. However, during follow-up after discectomy, significant interaction effects were found for RDQ score: Only in patients with MC at baseline, patients remained significantly more disabled (3.2 points p = 0.006) if they showed considerable disc inflammation compared to patients with mild inflammation. The additional analysis showed similar results in extruded discs, but no significant effects in bulging discs.ConclusionsAn interaction effect of MC and disc inflammation by macrophages is present. Only in patients with MC, those with considerable inflammation recover less satisfactory during follow-up after surgery.Graphic abstractThese slides can be retrieved under Electronic Supplementary Material.
Highlights
Materials and methodsPatients with lumbar disc herniation often suffer from radicular pain symptoms, the origin of which is not fully understood
This so-called functional inflammation response can explain spontaneous regression in herniation size [4]. They can excrete pro-inflammatory cytokines such as IL-6, IL8 and TNF-alpha, which have been associated with exacerbation of the pain symptoms, the so-called painful inflammation response [5,6,7]. This discrepancy in inflammation response is reflected in the inconsistent findings regarding the correlation between the presence of macrophages in herniated disc material and clinical symptoms [8, 9]
CD68 staining to identify macrophages resulted in the following distribution: 48 (40%) patients were scored as mild inflammation, 45 (37.5%) patients as moderate inflammation, and 27 (22.5%) patients as considerable inflammation
Summary
Materials and methodsPatients with lumbar disc herniation often suffer from radicular pain symptoms, the origin of which is not fully understood. Macrophages may subsequently induce a resorption process by excreting matrix metalloproteases [2], inducing apoptosis and degrading collagen fibres [3] This so-called functional inflammation response can explain spontaneous regression in herniation size [4]. They can excrete pro-inflammatory cytokines such as IL-6, IL8 and TNF-alpha, which have been associated with exacerbation of the pain symptoms, the so-called painful inflammation response [5,6,7] This discrepancy in inflammation response is reflected in the inconsistent findings regarding the correlation between the presence of macrophages in herniated disc material and clinical symptoms [8, 9]. The type of disc herniation should not be neglected when the characteristics of disc inflammation are studied
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