Transforaminal epidural steroid injections influence Mechanical Diagnosis and Therapy (MDT) pain response classification in candidates for lumbar herniated disc surgery

STUDY DESIGN: Prospective cohort study. BACKGROUND: Although lumbar radiculopathy is regarded as a specific diagnosis, the most effective treatment strategy is unclear. Commonly used treatments include transforaminal epidural steroid injections (TESIs) and Mechanical Diagnosis & Therapy (MDT), but no studies have investigated the effectiveness of this combination. MDT differentiates pain centralization (C) from non-centralization (NC), which indicates good vs. poor prognostic validity respectively. OBJECTIVE: The main aims were 1) to determine changes in Mechanical Diagnosis and Therapy (MDT) pain response classifications after transforaminal epidural steroid injections (TESIs) in candidates for lumbar herniated disc surgery and 2) to evaluate differences in short and long term outcomes for patients with different pain response classifications. METHODS: Candidates for lumbar herniated disc surgery were assessed with a MDT protocol and their pain response classified as centralizing or peripheralizing. For this study, only patients were eligible who showed a peripheralizing pain response at intake. All patients then received TESIs and were reassessed and classified using the MDT protocol, into groups according to pain response (resolved, centralizing, peripheralizing with less pain and peripheralising with severe pain). After receiving targeted treatment based on pain response after TESIs, ranging from advice, MDT or surgery, follow-up assessments were completed at discharge and at 12 months. The primary outcomes were disability (Roland-Morris Disability Questionnaire [RMDQ] for Sciatica), pain severity in leg (visual analogue scale [VAS], 0-100) and global perceived effect (GPE). Linear mixed-models were used to determine between-groups differences in outcome. RESULTS: A total of 77 patients with lumbar disc herniation and peripheralizing symptoms were included. Patients received an average of 2 (SD 0.7) TESIs. After TESIs, 17 patients (22%) were classified as peripheralizing with continuing severe pain. These patients underwent surgery and were not further evaluated. Eleven (14%) patients were classified as resolved, 37 (48%) as centralizing with significant less pain, and 12 (16%) as peripheralizing with significant less pain. None of these patients underwent surgery. Resolved and centralizer subgroups had better outcomes in terms of VAS and RMDQ than the non-operated peripheralizers at discharge and at 12 months. The succes rates (GPE) for the resolved, centralizing, and peripheralizing with less pain patients were 100%, 100% and 33% respectively at short term, and 100%, 92% and 50% respectively at long term. CONCLUSION: After TESIs, a peripheralizing pain pattern changed to resolved or centralizing in 62% of the patients. For the non-operated patients, those with a centralising pattern after TESIs reported better pain and disability outcomes than those with peripheralizing pattern at short and long term.