Transient Increases in Intracranial Pressure After Soccer Heading

Abstract

Objective To evaluate whether intracranial pressure (ICP) continued to stay elevated in trained athletes 24 hours after soccer heading. Methods Eight male subjects (21.7±1.7 years) were recruited from the UCSD soccer team to participate in the study. Baseline ICP and cardiovascular variables were recorded, and measurements were repeated after subjects underwent the heading trial. Acoustical evoked tympanic membrane displacement was used to estimate ICP, where decreasing volume displacement (-Vm) is associated with an increase in ICP. Mean arterial pressure (MAP) and heart rate (HR) were measured through the volume-clamp method. The heading trial consisted of 6 repeated headers of a soccer ball kicked from 32 meters away into a regulation goal. Follow up measurements of ICP, MAP, and HR were recorded 24 hours after heading trial. Measurements were taken in three randomized positions: 15° head-up tilt (HUT), 0° supine, -15° head-down tilt (HDT). Results At 15° HUT, baseline mean Vm was 37.81±133.21 nL, -20.82±158.27 nL immediately after heading trial (P=0.0482, paired t test), and 27.20±140.61 nL at 24 hours post soccer heading (P=0.1738, paired t test), corresponding to a significant increase in ICP immediately after the heading trial that then returns to baseline levels after 24 hours. At 0° supine, baseline mean Vm was -46.19±178.50 nL, -84.27±183.55 nL after heading trial (P=0.0321, paired t test) and -62.90±135.44 nL at 24 hours post soccer heading (P=0.5048, paired t test), corresponding to the same trend observed in the 15° HUT position. At -15° HDT, mean Vm was -148.48±196.07 nL at baseline, -187.02±186.19 nL after heading trial (P=0.1176, paired t test), and -151.10±174.86 nL at 24 hours post soccer heading (P=0.9329), corresponding to no significant increase in ICP at either time point. MAP and HR did not significantly change at any point after soccer heading. Discussions ICP significantly increased after soccer heading at 15° HUT and 0° supine but returned to baseline levels after 24 hours. ICP at -15° HDT, MAP, and HR did not significantly change immediately after soccer heading or 24 hours after soccer heading. While these results demonstrate a mild increase in ICP that subsides after 24 hours, athletes may experience these transient increases in ICP continuously for extended periods of time during their entire athletic careers. These cycles of increased ICP may result in a state of intermittent but persistently altered cerebral blood flow, which may suggest a health risk of participating in head contact sports such as soccer.