Current topics in sports-related head injuries: a review

Abstract

We review the current topic in sports-related head injuries including acute subdural hematoma (ASDH), concussion, and chronic traumatic encephalopathy (CTE). Sports-related ASDH is a leading cause of death and severe morbidity in popular contact sports like American football in the USA and judo in Japan. It is thought that rotational acceleration is most likely to produce not only cerebral concussion but also ASDH due to the rupture of a parasagittal bridging vein, depending on the severity of the rotational acceleration injury. Repeated sports head injuries increase the risk for future concussion, cerebral swelling, ASDH or CTE. To avoid fatal consequences or CTE resulting from repeated concussions, an understanding of the criteria for a safe post-concussion return to play (RTP) is essential. Once diagnosed with a concussion, the athlete must not be allowed to RTP the same day and should not resume play before the concussion symptoms have completely resolved. If brain damage has been confirmed or a subdural hematoma is present, the athlete should not be allowed to participate in any contact sports. As much remains unknown regarding the pathogenesis and pathophysiology of sports-related concussion, ASDH, and CTE, basic and clinical studies are necessary to elucidate the crucial issues in sports-related head injuries.

Fig. 1.

Catastrophic head injuries in American football. The graph shows the annual data on catastrophic head injuries in American football players.^, The incidence of catastrophic head injuries continues to rise particularly in players 18 years old or younger. The average yearly incidence from 2008 to 2012 was 2.38 times higher than in 1998 to 2002.

Fig. 2.

Catastrophic head injuries in Japanese students reported by the Japan Sports Council. The graph shows the number of elementary-, junior high-, and senior high school students aged 7–18 years who suffered catastrophic sports-related head injuries during the period from 1998 to 2011. Judo was a leading cause of death or severe morbidity; among 88 athletes with catastrophic sports head injuries, 40 participated in judo.

Fig. 3.

Judo-related catastrophic head injuries (2003–2011). The graph shows the number of students who suffered catastrophic judo-related head injuries in different school years. There were two peaks in the incidence of head injuries; one peak is seen in the first year of junior high school and the other in the first year of senior high school. Each column represents the number of injured judo participants. ES: elementary school, grade 1 to 6, JH: junior high school, JH1 (first year) to JH3 (third year), SH: senior high school, SH1 (first year) to SH3 (third year), US: university students.