Centralization in patients with sciatica: are pain responses to repeated movement and positioning associated with outcome or types of disc lesions?

Abstract

To determine the frequency of different patterns of centralization and their association with outcomes and MRI findings in patients experiencing sciatica. A prospective longitudinal cohort study of 176 patients with radicular pain below the knee, who all had an MDT clinical assessment. Based on their pain response, patients were divided into five groups: abolition centralization, reduction centralization, unstable centralization, peripheralization, and "no effect". Patients had an MRI. Overall, 84.8% of patients reported experiencing centralization, 7.3% peripheralized and 7.9% reported "no effect". The median reduction in RMQ scores across all the three centralization groups was 9.5 points at 3 months, and 12.0 points at 12 months. The peripheralization group improved similarly. The 'no effect' group improved significantly lower (p < 0.001), by 3.0 at both time points. Patients who centralized, and peripheralized had a significantly reduction in leg pain, the "no effect" group demonstrated a less favorable outcome (p < 0.02). There was no association between pain responses and the type of disc lesion. In patients with sciatica, centralization was common and associated with improvement in activity limitation and leg pain. Centralization was very common in ruptured disc therefore the study does not support the theory, that centralization only occurs if the intra-discal hydrostatic mechanism is functional.