Is the simple versus complex classification of concussion a valid and useful differentiation?

BACKGROUND: At the Second International Conference on Concussion in Sport, concussion was classified as "simple" or "complex" based largely on duration of clinical features. The purpose of the classification system was to assist clinicians in identifying higher grades of injury severity and guide injury management. The aim of the current paper is to review the validity and clinical usefulness of the simple versus complex classification system.

STUDY DESIGN: Qualitative review of the literature on concussion in sport, with a focus on time course of clinical recovery and prognostic factors.

INTERVENTION: Pubmed, Medline and Sport Discus databases were reviewed. Fifty journal articles were included in the review.

RESULTS: Prospective studies support the recovery of symptoms, balance deficits and cognitive impairment in the majority of concussed athletes within 10 days of injury. However, clinical factors that predict higher grades of injury severity or poor outcome following concussion remain unclear. At present, concussion severity can only be accurately determined in retrospect after all clinical features have resolved.

CONCLUSION: It is recommended that concussion in sport be considered as a single entity. Clinical factors that have demonstrated to be associated with longer duration of symptoms (for example, post-traumatic amnesia) or poor outcome (for example, repetitive head injury) may serve as "modifying" factors to assist the treating practitioner in identifying potential for higher grades of injury severity or adverse outcomes.