Scott L. Zuckerman, Andrew Kuhn, Michael C. Dewan, Peter J. Morone, Jonathan A. Forbes, Gary S. Solomon and Allen K. Sills
Sports-related concussions (SRCs) represent a significant and growing public health concern. The vast majority of SRCs produce mild symptoms that resolve within 1–2 weeks and are not associated with imaging-documented changes. On occasion, however, structural brain injury occurs, and neurosurgical management and intervention is appropriate.
A literature review was performed to address the epidemiology of SRC with a targeted focus on structural brain injury in the last half decade. MEDLINE and PubMed databases were searched to identify all studies pertaining to structural head injury in sports-related head injuries.
The literature review yielded a variety of case reports, several small series, and no prospective cohort studies.
The authors conclude that reliable incidence and prevalence data related to structural brain injuries in SRC cannot be offered at present. A prospective registry collecting incidence, management, and follow-up data after structural brain injuries in the setting of SRC would be of great benefit to the neurosurgical community.
Scott L. Zuckerman, Brian Holt Zalneraitis, Douglas J. Totten, Kolin E. Rubel, Andrew W. Kuhn, Aaron M. Yengo-Kahn, Christopher M. Bonfield, Allen K. Sills and Gary S. Solomon
A significant proportion of patients experience long-term symptoms after sport-related concussion (SRC), and several factors have been associated with this protracted recovery. Limited data exist on the role of socioeconomic status (SES) on SRC outcomes. The objective in this study was to conduct a preliminary investigation to determine the effect of SES on outcomes after SRC in student-athletes treated at a regional sports concussion center.
A retrospective cohort study of 282 middle school, high school, and collegiate student-athletes was conducted. An attempt was made to contact all patients seen at a comprehensive SRC center between January 2012 and May 2015 for in-depth interviews. Subsequent demographic data were collected. The SES was defined as follows: cost of living percentile, median income percentile, percentage of college graduates, percentage of homeowners, county type, and insurance status. Outcomes after SRC were defined as follows: days of symptom duration, days of missed school, and days of missed practice. Statistically controlled covariates included sex, race, age, body mass index, concussion history, neuropsychiatric history, and type of sport.
A total of 282 student-athletes consented and were studied. The median age was 15.8 years (range 11.6–22.2 years) and 61.4% of student-athletes were male. A previous concussion was incurred by 34.0% of student-athletes. Football was the most common sport (32.3%), followed by soccer (16.3%), and basketball (15.6%). The median symptom duration was 21 days (range 1–365 days); the median missed school days was 2 (range 0–90 days); and median for days of missed practice was 10 (range 0–150 days). After multivariate Cox regression analysis, no relationship between any of the 6 SES variables and symptom duration or missed practice was seen. However, individuals with private insurance had more missed days of school than those with public insurance (hazard ratio 0.46, 95% CI 0.26–0.83, p = 0.009).
In a preliminary study of middle school, high school, and collegiate student-athletes, SES had no impact on the outcomes of symptom duration and missed practice. However, for individuals with private insurance, the return to school was slower than for those with public insurance. This pilot study reveals the complex relationship between SES and SRC recovery, which demands further study with more accurate and validated assessments of SES.
Scott L. Zuckerman, Bryson B. Reynolds, Aaron M. Yengo-Kahn, Andrew W. Kuhn, Jacob T. Chadwell, Sarah E. Goodale, Claire E. Lafferty, Kyle T. Langford, Lydia J. McKeithan, Paul Kirby and Gary S. Solomon
Amid the public health controversy surrounding American football, a helmet that can reduce linear and rotational acceleration has the potential to decrease forces transmitted to the brain. The authors hypothesized that a football helmet with an outer shell would reduce both linear and rotational acceleration. The authors’ objectives were to 1) determine an optimal material for a shock-absorbing outer shell and 2) examine the ability of an outer shell to reduce linear and/or rotational acceleration.
A laboratory-based investigation was undertaken using an extra-large Riddell Revolution football helmet. Two materials (Dow Corning Dilatant Compound and Sorbothane) were selected for their non-Newtonian properties (changes in viscosity with shear stress) to develop an outer shell. External pads were attached securely to the helmet at 3 locations: the front boss, the side, and the back. The helmet was impacted 5 times per location at 6 m/sec with pneumatic ram testing. Two-sample t-tests were used to evaluate linear/rotational acceleration differences between a helmet with and a helmet without the outer shell.
Sorbothane was superior to the Dow Corning compound in force reduction and recovered from impact without permanent deformation. Of 5 different grades, 70-duro (a unit of hardness measured with a durometer) Sorbothane was found to have the greatest energy dissipation and stiffness, and it was chosen as the optimal outer-shell material. The helmet prototype with the outer shell reduced linear acceleration by 5.8% (from 75.4g to 71.1g; p < 0.001) and 10.8% (from 89.5g to 79.8g; p = 0.033) at the side and front boss locations, respectively, and reduced rotational acceleration by 49.8% (from 9312.8 rad/sec2 to 4671.7 rad/sed2; p < 0.001) at the front boss location.
Sorbothane (70 duro) was chosen as the optimal outer-shell material. In the outer-shell prototype helmet, the results demonstrated a 5%–10% reduction in linear acceleration at the side and front boss locations, and a 50% reduction in rotational acceleration at the front boss location. Given the paucity of publicly reported helmet-design literature and the importance of rotational acceleration in head injuries, the substantial reduction seen in rotational acceleration with this outer-shell prototype holds the potential for future helmet-design improvements.