Selective head-and-neck cooling as a treatment method for concussions in elite male rugby union players: the Clinical Observed Outcomes with Local HEad-and-neck cooling After Diagnosed concussions (COOLHEAD) study protocol.

Sports-related concussions (SRCs) typically occur when the brain is hyperthermic. Acute head-and-neck cooling should, therefore, reduce the brain's metabolic demands, with the potential to improve recovery following an SRC. Elite ice hockey players who underwent head-and-neck cooling after sustaining a concussion (SRC) showed reduced return-to-play times, although further investigation is warranted. This paper aims to describe the methods proposed for investigating the clinical effects and feasibility of acute head-and-neck cooling in elite male rugby union players. A quasi-experimental study will be conducted in two professional male rugby competitions (clusters): the United Rugby Championship 'intervention group' and the PREM Rugby 'standard care group'. Both groups will follow World Rugby's standardised, graduated return-to-play concussion management protocols. In addition to this, within 30 min of the SRC, the intervention group will be offered head-and-neck cooling for 45 min. The quantitative phase of the study will collect return-to-play times and clinical outcomes in both groups (sample size calculated: 100 concussions per cohort). The qualitative phase will explore the experiences of players and medical teams with the intervention. Intention-to-treat and per-protocol analyses, using appropriate regression modelling techniques, will adjust for possible confounders between the two groups, and thematic content analysis will be employed in the analysis of the respective phases. The Clinical Observed Outcomes with Local HEad-neck cooling After Diagnosed concussions study will provide evidence regarding acute head-and-neck cooling as a potential adjunct treatment to current concussion management in elite male rugby union.