How Can Animal Models Inform on the Transition to Chronic Symptoms in Whiplash?

In Brief Study Design. A nonsystematic review of the literature. Objective. The objective was to present general schema for mechanisms of whiplash pain and review the role of animal models in understanding the development of chronic pain from whiplash injury. Summary of Background Data. Extensive biomechanical and clinical studies of whiplash have been performed to understand the injury mechanisms and symptoms of whiplash injury. However, only recently have animal models of this painful disorder been developed based on other pain models in the literature. Methods. A nonsystematic review was performed and findings were integrated to formulate a generalized picture of mechanisms by which chronic whiplash pain develops from mechanical tissue injuries. Results. The development of chronic pain from tissue injuries in the neck due to whiplash involves complex interactions between the injured tissue and spinal neuroimmune circuits. A variety of animal models are beginning to define these mechanisms. Conclusion. Continued work is needed in developing appropriate animal models to investigate chronic pain from whiplash injuries and care must be taken to determine whether such models aim to model the injury event or the pain symptoms. Cellular and molecular neuroimmune mechanisms of pain are reviewed with a focus on chronic pain from whiplash. Specific animal models of painful facet capsular injury and nerve root trauma are presented. A brief discussion of confounding factors and implications for interpretations of animal models of whiplash pain is also provided.