Recreational Skiing Head Injury Literature Review

Purpose:

The purpose of this paper will be to review the literature on recreational skiing head injury. I would like to assess the incidence and, if possible, the severity of head injury. I also want to examine different mechanisms and other factors that may contribute to increases in head injury, and finally I want to review the use of helmets and make a case for using them or not. This study would focus mostly on recreational skiing, as the research mostly revolves around recreational versus competitive. Some research will be included regarding recreational snowboarders as well.

From the research I have examined so far, often ski injury is broken down into body parts; i.e. head, torso, extremity etc. This would make it easy to identify the prevalence of head injuries. Also, a majority of articles focus specifically on head injury rates from skiing.

Next, I would like to try to identify different factors that could lead to an increase in head   injury. Here is a list of things I could examine:

·         Previous head injury

·         Experience

·         What they were doing when it occurred

·         Riding preference (Park vs. Slopes) and Difficulty

·         Age

·         Time of day (beginning of ski session versus end of session, fatigue)

·         Percent of riders wearing helmets

·         Type of head injury

Research has looked into some of these areas but often not in extreme detail, so it may be difficult to answer these questions.

Research has been done on the efficacy of helmet use while skiing but some skiers continue to forgo wearing helmets. I would like to examine the evidence and make a case most likely in favor of using a helmet. If there is a high incidence and severity of head injury while skiers are wearing helmets, how useful are they?

I believe this paper would be beneficial to both recreational as well as healthcare providers. Skiers can read this and gather from it the potential risk of head injury they could suffer engaging in skiing and could pressure them into utilizing a helmet to protect them from these injuries. It would also further familiarize healthcare providers with these injuries. This paper could also identify factors that may increase the risk for head injury, informing both skiers and healthcare providers of these risks.

 

 

 

 

 

 

 

 

 

 

Title

 

Derek Jensen

 

Committee

 

University of Nevada, Las Vegas

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table of Contents

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Actual Thing

Introduction

Alpine skiing and snowboarding are very popular winter sports, totaling over an estimated 54 million trips by Americans during the 2016-2017 season.¹ However popular, the risk of injury in these sports can be high for participants.² In their six-year study of injury incidence rate at the largest ski resort in Finland, Strenroos and Handolin calculated an incidence rate of .96 injuries per 10,000 ski lift rides.² In these sports, no anatomical location is exempt from injury; this includes the head, spine, trunk and both upper and lower extemities.³ Of these injuries, the most traumatic and life threating are those that involve the head and brain. These injuries are often a result of collision with other participants, collision with fixed objects such as trees or poles, or contact of the head on the ground during a falling.^2-7 Costing the United States an estimated 56 billion dollars annually, the burden of head injury manifests economically as well as psychologically.⁸ Traumatic brain injury (TBI), the most severe form of head injury and defined as “bump, blow or jolt to the head that disrupts the normal function of the brain⁹,” accounted for 77.2% of head injuries suffered by subjects over a 14 year study.¹⁰ Though shown to be effective in reducing head injury, helmets are still forgone by a moderate percentage of the skiing and snowboarding population.⁵ This is perhaps due to the history of controversy surrounding helmets and the suggestion that they could potentially increase the incidence of neck injury. However, this idea has been thoroughly investigated and purported as false.^11-14 Researchers have attempted to investigate other factors that put individuals at risk for head injury, including experience level, terrain, and risk taking, in an effort to inform the public. The purpose of this paper will be to educate healthcare professionals and recreational skiers and snowboarders about the research pertaining to head injury in skiing and snowboarding, potential factors increasing the incidence of head injury, and a recommendation regarding helmets.

Head Injury

Head injury encompasses many pathologies including fracture, dislocation and intracranial pathology. In a study by Hentschel et al¹⁵ that identified the specific head injuries suffered by a population of skiers and snowboarders, they found concussion and skull fractures as the most common pathologies present, accounting for 24% and 21% respectively. In addition, cerebral contusion, epidural hematoma, subdural hematoma and subarachnoid hemorrhage were observed, to a lesser degree, accounting for 11%, 8%, 3.6% and 3.6% of head injuries respectively. Also, interventricular hemorrhage, contusion and laceration constitute a small percentage of observed head injuries in skiers and snowboarders.^16,17 TBI, which falls under the branch of head injury but encompasses its most severe pathologies, includes concussion, cerebral contusion and cerebral hemorrhage. These specific injuries can be quite debilitating and potentially life threatening if not treated properly and within appropriate time. Fortunately, multiple studies examining head injuries have found their occurrence in the snow sport population to be quite low.^{2,3,5-8,10,11,14-24}

The most recent comprehensive review of skiing and snowboarding injuries compiled by Owens et al³ reports a head injury rate of around 15%. Though low, the exact rate of head injuries suffered by snow sport participants varies study to study. A recent study by Dickson et al¹⁶ observed head injury, as compared to all injuries, varied between 8.3% and 9.6%. This contrasts with Wasden et al² who calculated a head injury rate of 20% for skiers and 27% for snowboarders they measured. Polites et al²⁴ observed an incidence rate of nearly 25% in the child aged skiers and snowboarders treated at trauma centers in the United States over four years. One possible explanation for the inconsistency in injury rates may be because not all injured persons are accounted for. Some injuries may not be severe enough to require medical care and therefore are not recorded. As result, missing data creates the case where overall injury incidence may be higher and head injury incidence is perhaps lower, but because it more often requires attention from ski patrol, head injury is more often accounted for.

TBI

It appears from recent studies that overall head injury incidence is on the decline.²⁰ However, an increase in the occurrence of TBI has been witnessed in recent year in tandem with this overall decrease of head injuries.²⁰ This change has been observed in adults as well as children and adolescents.¹⁰ Ackery et al²⁰ found that this increase in TBI coincides with a slight, but steady, increase in the number of fatalities observed over the 21 ski seasons included in their data. The National Ski Areas Association (NSAA) publishes a yearly report of fatality incidents that occurred at U.S. ski resorts during the previous ski season. The NSAA report of the 2016-2017 season notes a total of 44 fatalities, a 12% increase from 39 fatalities observed the previous year.²⁵ Though fatality is most often attributed to “massive head, neck or thoracoabdominal injury,”²⁰ TBI accounts for roughly 50-88% of skiers or snowboarders who perish as result of their injuries.

As previously discussed, TBI constitutes head injuries resulting in concussion, cerebral contusion or cerebral hemorrhage. It should be no surprise that TBI is an issue researchers are beginning to observe more often in the snow sport population. Falls, the primary culprit in TBI, speeds, objects and other persons, and potential resultant head acceleration forces are more than capable of inflicting significant injury to skiers and snowboarders.²⁶ Bailey et al²⁶ modeled impact forces in dummies similar to those suffered in snowboarders catching their backside edge, known as the opposite-edge phenomenon. By catching their backside edge, a snowboarder will fall backwards, unable to catch themselves, resulting in their shoulders and head striking the ground. Researchers found that rotational forces at the head during this fall exceeded those necessary to induce mild TBI at slow (19.6 km/h), medium (22.5 km/h), and fast (27.6 km/h) speeds on hard snow, such as that found on groomed slopes. On soft snow, such as powder, forces were lesser but still within the threshold to induce injury. More generally, collisions and falls by both skiers and snowboarders on gentle slopes, intermediate slopes, and during jumping, account for the majority of TBI cases.^5,26-33 A unique case where TBI can also be found is in victims of avalanches.²¹ Of those victims, 61% had some level of head injury either resulting directly in death or in combination with death by asphyxiation. Another interesting note with TBI is the percentage of those injured who have alcohol in their systems at the time of injury. In one study only 3.1% of skiers and snowboarders with TBI were found to have consumed alcohol prior to their injuries.¹⁸

There is no denying that the recent evidence of an increase in recorded TBI is disturbing. However, Graves et al¹⁰ offer a potential alternate explanation for this phenomenon. Following their acknowledgement that both sports inherently come with the risk of head injury, they offer the alternative explanation that perhaps there is an increase in the accuracy of diagnosing TBI without an actual increase in the incidence of the injury itself. Concussion, one most common forms of TBI, is a hot topic in current sports culture. Movies like Concussion, news of the controversy surrounding the NFL and their concussion policy, and emerging research on the topic all have the potential to inform the public on the matters of concussion, TBI and head injuries. Regardless of whether this explanation is partially responsible for the increase in recorded TBI, it is important for participants in these sports to understand different factors that could potentially increase or decrease their risk of suffering a head injury. First to be examined is the role of helmets.

Helmets

With the increase in the incidence of TBI recorded by some researchers,²⁰ and the threat of many different types of head injury, action must be taken by the individual to decrease their risk of suffering one of these injuries. The most straightforward means of decreasing the risk of head injury is by wearing a helmet.^{3,4,10-12,14,19-21,34-37} This claim isn’t only evidenced by the multiple studies showing a clear reduction in head injuries in helmet wearing populations, but also by studies whose samples of head injured patients are made up almost entirely of persons not wearing helmets.^17,18 When comparing skiers with head injuries to their uninjured, helmet wearing, counterparts, a 35%-60% reduction in risk of head injury was observed.^12,14 Both a systematic review²⁰ and meta-analysis¹² observed the effectiveness of helmets and came to the same conclusion; helmets reduce the incidence of head injury amongst skiers and snowboarders and enhanced promotion of injury prevention including helmet use should be emphasized for all snow sport participants. Also, no differences were observed in effectiveness between men and women or youth and adults. In addition to reducing risk of head injury, it has also been reported that helmets lessen the severity of head injuries their wearers suffer.³⁶ Greve et al³⁶ found that helmet wearers had a significantly lower incidence of loss of consciousness compared to non-helmeted head injured subjects. The reduction in the risk of head injury also translates to a reduction in fatality risk for helmet users.³⁷ Non-helmeted skiers and snowboarders were reported to be 2.3 times more likely to die from head injury than helmeted participants. Furthermore, helmets have also demonstrated the ability to provide some protection from injuries to the neck.³⁷

Evidence of helmets providing a protective effect for the neck contrasts the long-standing controversy that helmet users are at an increased risk for neck injury. This idea is perpetuated by critics who cite the additional size and weight added by the helmet as the problem.¹² The added weight and dimensions is thought to increase the risk of harmful neck movements during falls and collisions. Overwhelmingly, researchers have found little to no evidence of this occuring.^{3,11,12,19,20,36} This was true for both adults as well as children, who critics say are more at risk because of their greater head to body ratio.¹² Another criticism regarding helmets is their potential lack of protection from forms of TBI, specifically concussion. Sulheim et al¹¹ observed a reduction in the protective effect of skiing and snowboarding helmets over a ten-year period. They attributed some of this change to possible new skiing trends by participants including riding off trail or in the terrain park. Dickson et al¹⁶ compared the increase in helmet use, from 69% to 80% of skiers and snowboarders, over a five-year period at Canadian skiing resorts with the amount of reported head injuries from these resorts. They found a non-significant increase in reported head injuries over this five-year period with the most common injury these subjects experienced being concussion. Though helmets have been proven effective in preventing contact of the skull with objects like trees or surfaces like snow, greatly reducing the occurrence of injuries such as bruises, lacerations, and fractures, they cannot prevent the brain from contacting the interior of the skull. This must be a focus of helmet manufactures going forward; development of helmets need to include protection for the mechanisms most often attributed to concussion.

One point of contention that researchers haven’t quite come to an agreement on, regarding helmets, is idea of risk compensation brought about by participants wearing helmets. It is thought that with the extra protection offered by helmets, users overestimate these effects and attempt bigger and more dangerous maneuvers they’d otherwise not when not wearing a helmet. One study³⁸ examines this question specifically while others^12,14,16,36 pose this question briefly when postulating why serious injuries are still seen in those wearing helmets. Scott et al³⁸ conducted a survey whereby skiers and snowboarders were interviewed while riding the chair lift. Interviewers asked helmeted subjects whether they skied/snowboarded faster, slower, or about the same as they did when they didn’t wear a helmet. Interviewers then asked if subjects challenged themselves more, less, or about the same as when they were not wearing a helmet. Finally, riders were asked if they wore helmets while participating in other sports. As for those interviewed without a helmet, they were asked if they now skied/snowboarded faster, slower or about the same speed and if they challenged themselves more, less, or about the same as they had in previous seasons. Researchers found no evidence to support the risk compensation hypothesis. They also found that helmet use was associated with less risky behavior rather than increase risky behavior. Researchers did however observe a few differences in demographics of helmet users, namely older, more experienced skiers were more likely to wear helmets compared to younger, less experienced snowboarders. Regardless of these differences and controversies surrounding helmets, there has been a major increase in their use by skier and snowboarders. The NSAA claims nearly 83% of participants they interviewed during the 2016-17 season wore helmets.³⁹ That is an increase of over 58% since the 2002-02 season and marks the 15^th consecutive year utilization has reportedly increased. Unfortunately, even though usage has increased, overall usage is still not 100% and snowboarders make up the larger percentage of those who still forgo helmet use.

Ski vs Snowboard

This difference in the percentage of helmet users between skiers and snowboarders foreshadows other differences existing between the two sports. Two studies^13,24 observed skiers wearing helmets more often, 42% vs 32%¹³ and 46% vs 34%,²⁴ than snowboarders. Neither study attempted to elaborate on why this difference was observed. Perhaps differences in the demographics of the two populations plays a role. Male uptake of skiing and snowboarding, when combined, is slightly higher than that of females.^18,40 However, a significant difference is observed when looking at snowboarding specifically. Roughly 60-75% of the population is male and tends to be younger, with roughly 50% of participants falling into the age bracket of 12-24 years old. This leaves open the possibility that because young males are more likely to ride in terrain parks⁵ and thus more likely to take risks, they may see helmets as less vital to their arsenal of protective equipment. This difference in the percentage of those who wear helmets also appears to influence differences in head injury.

The lack of helmet use amongst snowboarders doesn’t bode well for their relative risk of head injury compared to skiers.  Multiple studies find snowboarders having a higher rate of head injury.^{3,18-20,26,28} Wasden et al²⁸ found a head injury rate of 27.3% for snowboarders and 20.4% for skiers. This was slightly lower than Owen et al,³ listing rates of 33% and 28% for snowboarding and skiing respectively. Chaze et al¹⁹ reported snowboarders were 1.5-3 times more likely to suffer a head injury than their counterparts whileanother study observed head injury in snowboarders occurring at a rate of 6.33 head injuries per 100,000 snowboarder days.²⁰ The head injury rate calculated for skiers was 1.03 head injuries per 100,000 ski days. Rust, Gilmore and Treme (2013) conducted an interesting study investigating the influence snowboarding, as a sport, has on injury.⁴¹ Snowboarding was relatively new and unpopular until the 1990s, and as a result many ski resorts did not allow snowboarding. Rust et al⁴¹ seized the opportunity to examine injury rates and patterns at the Taos Ski Valley resort two years prior and two years following the approval of snowboarding. They found the overall rate of injury increased from 206.7 injuries to 233.8 injures per 100,000 visits. An influx of upper extremity and head injuries was also noted. Researchers proposed more beginners, a younger risk-taking population, and extra traffic on the mountain as some of the reasons this increase was seen. Not only does the rate of head injury differ between the two sports, but also does the characteristics of these head injuries.

When speaking of areas of the skull that are most often injured, snowboarders have a significantly higher incidence of injury to the occipital region.^17,19,42 Skiers on the other hand tend to suffer more trauma to the frontal portion of their skulls and overall have a greater risk of fracture.^15,18,19,28 Research by Levy et al¹⁸ demonstrates this may be due to the mechanisms which skiers and snowboarders suffer their injuries. They found skiers were more likely to be injured by collisions compared to snowboarders who more often suffered injuries from falling. Nakaguchi and Tsurumi (2002) attribute this greater chance of falling for snowboarders to the nature of how they ride, both feet fixed to the board increasing the difficulty of catching ones-self during a fall, and to the previously discussed opposite-edge phenomenon.⁴¹ Regarding TBI, snowboarders suffer these injuries more often likely due to their greater propensity to fall.^17-19,42 In one study, 71% of head injured snowboarders suffered cerebral hemorrhage, compared to only 28% of skiers.¹⁵ Higher incidences of TBI translates to lower average Glasgow Coma scores, more trips to the intensive care unit (ICU), longer stays at hospitals, and greater neurological impairment upon discharge for snowboarders.^15,19  In addition to which sport participants take-up, terrain and riding style contribute to skiers and snowboarders risk of head injury.

Riding Preference and Terrain

Predominately, skiers and snowboarders navigate the different groomed slopes and defined trailer resort have to offer. However, a subset of the population partakes in the more extreme aspects of the sports. Events like the Olympics and X Games showcase elite level riders doing tricks involving jumps, boxes and rails. Recently, terrain parks, where these features are found, have been become more common at ski resorts allowing for recreational riders to attempt tricks.⁷ Unfortunately, researchers have found riding in the terrain park or off-piste, as in off the groomed trails, increases the incidence of injury as well as the risk of severe injury.^5,7,14,33,36 Fukuda et al¹⁷ identified early on that attempting jumps put riders at increased risk of head injury. Goulet et al⁷ later looked specifically at-risk factors associated with riding in terrain parks and slopes accommodating for tricks and found an increased risk for head and body injury, injuries requiring evacuation by ambulance, and increased risk of severe injury. It was also noted that a jump over two meters increased the risk, by 20% and 77%, for spinal injury in skier and snowboarders respectively. Brooks, Evan and Rivara (2010) took a detailed look at injuries suffered in terrain parks and compared them to those suffered by riders on traditional slopes. Injuries found more commonly in the park were concussions and fractures involving the head, face, and back. These injuries also more often required hospital transport. Loss of consciousness was more prevalent among park riders and even those riders wearing helmets.³⁶

While riding in terrain parks is popular among riders, riding off the groomed slopes into the trees is also enjoyed but a percentage of the population, but presents an increased risk of injury.^7,14,36 As previously stated, skiers tend to obtain many of their head injuries by striking objects, like trees.¹⁸ Snow that isn’t groomed can hide potential hazards such as rocks, stumps, and fallen trees that can be struck or interfere with riding. Riding off trail also means riding on snow that hasn’t been conditioned and is at the mercy of the elements. Greve et al³⁶ compared the typical conditions of snow found in Colorado to that found in Vermont. Injury risk was also examined, and they found riders were more likely to strike stationary object and lose consciousness in the Northeast. Researchers postulated that because the Northeast sees warmer winter temperatures, this allows for snow to melt and freeze into ice. Ice creates a more solid surface, increasing the difficulty of riding, potential for loss of control, and provides a more potent point of contact. In addition to variation is winter temperature throughout the country, weather can vary day to day at resorts. Inclement weather is harmful and increases the risk of injury substantially.³⁰ Weather that is potentially dangerous includes wind, clouds, and precipitation, all of which can impair vision. Impaired vision increases the chance of colliding with objects or other riders. One way ski resorts can help riders in the case of inclement weather is providing signage throughout the resort. In the case of impaired vision, lessening the ability to identify trails, signs could help direct skiers and snowboarders down the mountain and to safety.

An emerging setting where skiers and snowboarders are being found is in urban environments.³³Features similar to boxes and rails found in terrain parks, in addition to building to jump off of, and stairs, make urban areas inviting to some riders. Stenroos and Handolin (2017) obtained records of skiers and snowboarders admitted to the Helsinki University Hospital suffering from injuries obtained while riding in the Greater Helsinki area. Grouping injuries into either ski slope, terrain park, or urban, researchers found as a percentage, urban riders were more often admitted to the ICU. These patients also suffered from traumatic subdural hemorrhage 26% of the time compared to 3% for slope riders and 14% for terrain park riders. Interestingly, similar to previous studies, this study found those who suffered severe injuries more often consider themselves experts.

Experience

While self-reported skill level leaves an area of subjective debate, researchers aren’t debating the fact that experienced riders sustain more severe injuries compared to their less experienced conterparts.^{5,11,27,30,37} Koyama et al³⁰ conducted the most thorough study of this phenomenon. They found both groups had a high incidence of trauma to the occiput, 56.2% for beginners and 43.9% for experts, but the percentage of injury to the frontal portion of the skull was higher in experts, 21.9% versus 14.8%. These differences likely stem from the mechanisms of injury. Both groups were most likely to suffer injuries by falling but falls accounted for the majority in beginners while experts also suffered injury more often by collision. Furthermore, amnesia and loss of consciousness were present more often in experts. Resultant injuries differed as well, with beginners being diagnosed with subdural hematoma at a higher rate. Fractures of the skull and face were consistently higher for experts.  Examining multiple factors contributing to injury, Hume et al³⁷ also observed differences between beginners and experts. While beginners were far more likely to sustain an injury, mostly from falls, experts sustained more severe injuries, often as result of jumping. While experience level appears to offer interesting comparisons, age groups were also shown to present differently in the research.

While skiing and snowboarding are sports individuals can pick up at almost any time in their life, the predominant age of beginning individuals is under fifteen.^10,24,30 Regarding injury rate and severity, age and experience share some parallels. In three studies,^11,18,24 riders aged 30+ were classified as “older” and were compared to younger, <30 years old, patients. Though they suffered less total head injuries and similar mechanisms, head injuries in the older population were more often severe, required rehabilitation, and resulted in mortality. Recalling the discussion on TBI, Graves et al¹⁰ examined the incidence rate of TBI in younger riders. Split into two age groups, pediatric aged 4-12 and adolescent aged 13-17, they found a higher rate of TBI in adolescents compared to pediatric, 82% versus 69% respectively. TBI was associated with skiing most often for pediatrics and snowboarding for adolescents. Shockingly, researchers showed, compared to the 1996 season, the 2009 season had a 111% higher TBI risk ratio for pediatrics and was 250% higher for adolescents. Graves¹⁰ cites changes in riding behavior, increased popularity of snowboarding, the proliferation of terrain parks, and better recognition of TBI as possible explanations for the surge in reported cases.

In addition to age and experience, equipment has also been shown to influence injury risk. While helmets have demonstrated to be beneficial in decreasing head injury, rental equipment has been shown to increase risk of injury.³⁷ Typically, rentals include boots, bindings, and skis/snowboard. It is uncertain from this study if it specifically the equipment or its maintenance to blame for this higher risk of injury. In concert with previous discussion, those who utilized rental equipment were usually younger and less experience individuals. It wouldn’t be a stretch to conclude that all those factors come together and result in a higher incidence of injury.

Take home points

Now that the evidence has been presented, what things can be taken and put into practice by skiers, snowboarders, healthcare professionals, and ski resorts to try to reduce the incidence of head injury?

• Helmets should be worn by all individuals who ski and snowboard.
• Skiers and snowboarders need to educate themselves on what head injuries are and how to recognize when they, or someone they know, have sustained one.
• Beginners should understand they are at greater risk of injury and should seek out instruction from experienced riders or coaches and avoid progressing to more difficult tasks until they are ready.
• If rental gear must be used, ensure it is properly fitted and minimize risky behavior.
• Skier and snowboarders need to be honest with themselves regarding self-assessment of their skills before attempting complex tricks or jumps.
• Weather reports should be checked before setting out to avoid potentially hazardous conditions.
• Healthcare professionals should familiarize themselves with the different pathologies injured skiers and snowboarders could present with, how to recognize them, and develop a plan to of action in the case of severe injury.
• Ski resorts and helmet manufacturers must devise different ways to advocate for helmet use such as information campaigns and role models.
• Helmet manufacturers need to continue research and development into helmets that better protect users from concussion.
• Ski resorts must ensure proper signage is on display throughout the resort notifying riders of the increased dangers of the terrain their riding on, i.e. terrain park or off-piste.
• Terrain parks could be designed with more difficult features at the beginning to discourage lesser skilled riders from entering the park.

Conclusion

Skiing and snowboarding have found their way into the hearts of millions of people around the world. However, like every rose, skiing and snowboarding have their thorn. Head injury, though uncommon, is an ever-present danger to riders of all ages and experience levels. Having read this paper, skiers, snowboarders, and healthcare professionals should have a better understanding of the head injury risk associate with these sports. Also provided, is evidence of different factors contributing to increasing the risk of head injury and ways to help decrease that risk. Wearing helmets and forgoing risky behavior are a few of the ways riders can effectively, and cheaply, decrease their risk of suffering a head injury. Further research should examine what exactly beginners do that put themselves at increased risk of injury. Also, further research into helmet design should focus specifically on the development of helmets that can better dissipate forces and decrease the incidence of concussion.

Word Count: 4412

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