Prevalence of Traumatic Findings on Routine MRI in a Large Cohort of Professional Fighters

BACKGROUND AND PURPOSE:Previous studies investigating MR imaging abnormalities among fighters have had small sample sizes. This investigation assessed a large number of fighters using the same conventional sequences on the same scanner.MATERIALS AND METHODS:Conventional 3T MR imaging was used to assess 499 fighters (boxers, mixed martial artists, and martial artists) and 62 controls for nonspecific WM changes, cerebral microhemorrhage, cavum septum pellucidum, and cavum vergae. The lengths of the cavum septum pellucidum and cavum vergae and the ratio of cavum septum pellucidum to the septum pellucidum lengths were assessed.RESULTS:The prevalence of nonspecific WM changes was similar between groups. Fighters had a prevalence of cerebral microhemorrhage (4.2% versus 0% for controls, P = .152). Fighters had a higher prevalence of cavum septum pellucidum versus controls (53.1% versus 17.7%, P < .001) and cavum vergae versus controls (14.4% versus 0%, P < .001). The lengths of the cavum septum pellucidum plus the cavum vergae (P < .001), cavum septum pellucidum (P = .025), and cavum septum pellucidum to the septum pellucidum length ratio (P = .009) were higher in fighters than in controls. The number of fights slightly correlated with cavum septum pellucidum plus cavum vergae length (R = 0.306, P < .001) and cavum septum pellucidum length (R = 0.278, P < .001). When fighters were subdivided into boxers, mixed martial artists, and martial artists, results were similar to those in the whole-group analysis.CONCLUSIONS:This study assessed MR imaging findings in a large cohort demonstrating a significantly increased prevalence of cavum septum pellucidum among fighters. Although cerebral microhemorrhages were higher in fighters than in controls, this finding was not statistically significant, possibly partially due to underpowering of the study.

Multiple sports such as boxing, mixed martial arts, football, and soccer involve repetitive head trauma in young people, and this trauma is accumulated over many years. Many studies have attempted to describe conventional MR imaging findings associated with repetitive head trauma in the hope that an early in vivo diagnosis may preclude further trauma and help guide possible treatment.^1–9 However, these studies have often involved a small number of athletes, leading to variable findings and a low significance of results.^10,11 In some studies, MR imaging results were normal for athletes with head trauma,^7,9 whereas other studies demonstrated a variably increased prevalence of cerebral microhemorrhage (CMH),^4,5 nonspecific WM changes (NSWMCs),¹¹ or cavum septum pellucidum (CSP)/cavum septum pellucidum and vergae (CSPV).^1,2,10Regarding professional fighting, previous studies have similarly demonstrated the occurrence of imaging abnormalities, with imaging findings ranging from smaller volumes in structures such as the thalamus, vermis, and hippocampus and microhemorrhages in the parenchyma to macrohemorrhages such as subdural hematomas and parenchymal contusions.^{4–6,8,12,13} However, these studies were also limited by small sample sizes and a relatively low prevalence of microhemorrhages, so the calculated increased prevalence was not found to be statistically significant.^4,5Other studies have demonstrated a higher incidence of CSP among fighters, with some research finding a trend toward significance in fighters versus controls.¹⁰ However, an early large study of fighters demonstrated increased CSP prevalence in controls rather than in fighters.³ More recent studies in retired professional American football players found that the prevalence and size of the CSP were increased in the athletes versus controls.^2,14 Comparing these studies is complicated by differences in patient populations (eg, different sports, various age groups, current athletes versus retired athletes).^2,4,5,14 Additionally, even though an increased prevalence of CSP has been demonstrated among fighters in previous research, neuroradiologists disagree over whether this is a manifestation of trauma or simply a normal variant.Other conventional MR imaging findings in patients with repetitive head trauma include the presence of NSWMCs.⁷ However, some research into repetitive head trauma has demonstrated normal imaging findings in these patients.¹¹ This finding is consistent with our anecdotal experience.In this study, we chose to focus on a sport with a known high incidence of repetitive head trauma (professional fighters), using a large sample size and ensuring that all fighters were scanned with the same protocol on the same 3T MR imaging scanner. We sought to assess the prevalence of NSWMCs, CMH, and CSP/CSPV among these fighters versus the prevalence of these imaging abnormalities among healthy controls.