Assessing Head/Neck Dynamic Response to Head Perturbation: A Systematic Review.

BACKGROUND: Head/neck dynamic response to perturbation has been proposed as a risk factor for sports-related concussion.

OBJECTIVES: The aim of this systematic review was to compare methodologies utilised to assess head/neck dynamic response to perturbation, report on magnitude, validity and reliability of the response, and to describe modifying factors.

METHODS: A systematic search of databases resulted in 19 articles that met the inclusion and exclusion criteria.

RESULTS: Perturbation methods for head/neck dynamic response included load dropping, quick release and direct impact. Magnitudes of perturbation energy varied from 0.1 to 11.8 J. Head/neck response was reported as neck muscle latency (18.6-88.0 ms), neck stiffness (147.2-721.9 N/rad, 14-1145.3 Nm/rad) and head acceleration (0.2-3.8g). Reliability was only reported in two studies. Modifying factors for head/neck response included younger and older participants presenting increased responses, females showing better muscular reactivity but similar or increased head kinematics compared with males, and bracing for impact limiting muscular activity and head kinematics.

DISCUSSION: Substantial differences in experimental and reporting methodologies limited comparison of results. Methodological factors such as impact magnitude should be considered in future research.

CONCLUSION: Each methodology provides valuable information but their validity for anticipated and unanticipated head impacts measured in vivo needs to be addressed. Reports on head/neck response should include measurement of transmitted force, neck muscle latency, head linear and rotational accelerations, and neck stiffness. Modifying factors of anticipation, participants' age, sex, and sport are to be considered for head/neck dynamic response.

PROSPERO REGISTRATION NUMBER: CRD42016051057 (last updated on 27 February 2017).