Evidence for central sensitization in chronic whiplash: a systematic literature review.

BACKGROUND AND OBJECTIVES: It has been suggested that sensitization of the central nervous system plays an important role in the development and maintenance of chronic (pain) complaints experienced by whiplash patients. According to the PRISMA guidelines, a systematic review was performed to screen and evaluate the existing clinical evidence for the presence of central sensitization in chronic whiplash. DATABASES AND DATA TREATMENT: Predefined keywords regarding central sensitization and chronic whiplash were combined in electronic search engines PubMed and Web of Science. Full text clinical reports addressing studies of central sensitization in human adults with chronic complaints due to a whiplash trauma were included and reviewed on methodological quality by two independent reviewers.

RESULTS: From the 99 articles that were identified, 24 met the inclusion criteria, and 22 articles achieved sufficient scores on methodological quality and were discussed. These studies evaluated the sensitivity to different types of stimuli (mechanical, thermal, electrical). Findings suggest that although different central mechanisms seem to be involved in sustaining the pain complaints in whiplash patients, hypersensitivity of the central nervous system plays a significant role. Persistent pain complaints, local and widespread hyperalgesia, referred pain and (thoracic) allodynia, decreased spinal reflex thresholds, inefficient diffuse noxious inhibitory controls activation and enhanced temporal summation of pain were established in chronic whiplash patients.

CONCLUSIONS: Although the majority of the literature provides evidence for the presence of central sensitization in chronic whiplash, underlying mechanisms are still unclear and future studies with good methodological quality are necessary. In addition, international guidelines for the definition, clinical recognition, assessment and treatment of central sensitization are warranted.