The centralization phenomenon of spinal symptoms--a systematic review.

The centralization phenomenon was first described 20 years ago. It refers to the abolition of distal pain emanating from the spine in response to therapeutic exercises. Since then a number of papers on the subject have been published. A review of current knowledge is appropriate. Selection criteria were established prior to a computer-aided search for published papers. Two reviewers independently extracted data and checked quality; a third reviewer resolved any disagreements. A narrative review was conducted based on the findings. The review primarily considered prevalence, reliability of assessment, and prognostic significance. These have been most commonly reported, and are important to establish the clinical worth of this symptom response. Fourteen studies were identified. Quality of studies varied; prognostic studies were given a mean score of 3.3 out of 6 by using established quality criteria. The prevalence rate of pure or partial centralization was 70% in 731 sub-acute back patients, and 52% in 325 chronic back patients. It is a symptom response that can be reliably assessed during examination (kappa values 0.51-1.0). Centralization was consistently associated with a range of good outcomes, and failure to centralize with a poor outcome. Centralization appears to identify a substantial sub-group of spinal patients; it is a clinical phenomenon that can be reliably detected, and is associated with a good prognosis. Centralization should be monitored in the examination of spinal patients.