The diagnostic credibility of second impact syndrome: A systematic literature review

Objectives: The purpose of this review was to examine current literature to determine whether or not enough evidence exists to support a World Health Organization (WHO) recognized ICD-10 case definition for Second Impact Syndrome (SIS). Design: Systematic literature review. Methods: A sensitive search strategy was developed in order to include all relevant literature. Data were extracted and placed into a diagnostic framework constructed based upon previously accepted ICD-10 diagnoses. The quality of included studies was assessed using a checklist developed specifically for case reports. Results: The literature search yielded 338 articles. After duplicates were removed, the remaining 222 articles were screened. Seventy-five articles were assessed for full-text eligibility, which resulted in eight case studies appropriate for this review. Significant information regarding imaging and confirmed signs and symptoms is mixed or absent. Information exists to support possible at-risk populations, signs and symptoms. Conclusions: At present, there lacks a unique presentation scheme of SIS to support a standardized WHO case definition. Furthermore, future studies are needed to better understand and define at risk populations, diagnostic signs and symptoms, and the multisystem consequences of Second Impact Syndrome. (C) 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.