Fatal Facts About Helmets

A Neurosurgeon Speaks the Truth

Editors Note: The following article demonstrates one of several deadly side effects of helmet use. Although Dr. Cooter recommends limited use, his arguments directly relate to our freedom F.I.G.H.T. program attack.

During World War II, an English neurosurgeon named Cairns compared the head injuries of crashed motorcyclists wearing helmets. Cairns, a Professor of Neurosurgery at Oxford University, noted that helmeted motorcyclists who had broken their facial bones had less serious brain injuries. Clearly, some impact energy had been absorbed by the face or the helmet. From those early studies, the suggestion came that all motorcyclists should wear a helmet.

The only types available then were “inverted pudding bowl” styles that barely covered the short hair style of the day. These had an inner lining of cork or pulp that was used to absorb energy. During the 1960s, the fighter pilot style became popular because it covered the whole scalp, came in colorful fiberglass shells, and had better energy absorption material inside. Gradually helmet standards arose to ensure that helmets were constructed to a standard level that assured adequate impact performance in controlled helmet impact tests.

During the 1970s, full-face helmets (fighter pilot style plus facial protection) gained popularity. Manufacturers argued that if that fighter pilot style helmet had a chin bar, then the whole head and face could be protected. But this presented the helmet standards committees with a dilemma: How to test the performance of the chin bar component when no one was sure about how far it should deflect upon impact? Some said the chin bar should be soft and pliable. Others said it should be hard and inflexible. The rigid school won, and efforts were made to stiffen the chin bar by incorporating strong materials to increase its rigidity.

Early medical reports of facial injury patterns in motorcyclists supported the use of full-face helmets because hospital accident and emergency departments were treating far fewer facial cuts and abrasions among bikers wearing full facial protection. Indeed, it became rate to see an injured motorcyclist with a facial bone fracture if he wore a full-face helmet. All was well for motorcyclists who came to hospitals for treatment after a crash that involved a head impact.

But what about that ever-growing band of motorcyclists who didn’t make it to the hospital? Many died in helmets that fitted well, were well adjusted, and were firmly in place at the time of the crash. Of course, some of these had fatal chest and abdominal injuries, but too many seemed to be dying from impacts they should have survived.

During the 1980s, reports from road accident research units worldwide showed an increasing incidence of a particular fatal skull injury among motorcyclists wearing full-face helmets. This common fatal injury was a skull base fracture — a severe crack across the bones on which the brain sits. To try to explain how these devastating injuries were happening, some associates and I looked in depth at a small number of motorcyclists who had been fatally injured while wearing full-face helmets. At this time, the latest X-ray equipment available for patients with head injuries was computerized CT scanning (CAT scanning). CAT scans could be converted into three-dimensional images to help plan the surgery that crash victims often required. Using CAT scanning techniques, we compared the patterns of injury among 50 motorcyclists admitted to hospitals with 24 motorcyclists killed from similar impacts during the same period. We retrieved the helmets worn and also studied them with the CAT scanner.

Each motorcyclist’s head was considered as a four-layered unit: 1) the helmet, 2) the scalp and facial skin, 3) the skull and facial bones, and 4) the brain. Detailed scientific information was gleaned from each of these layers. That information was then fed into a computer-based coding system for analysis. In addition to the CAT scan information, a detailed autopsy was performed on the fatally injured group. An independent neuropathology review was also performed on the brain of each motorcyclist killed.

When analyzed, our results showed that motorcyclists with broken facial bones usually had been wearing helmets that gave little or no facial protection. Furthermore, they had little on the way of brain injury. In contrast, those motorcyclists killed outright often had no facial injury, even if they suffered an impact to the front of the helmet. They did, however, have skull base fractures and unsurvivable brain injuries. Apparently, the blow to the chin bar had been transmitted to the chin strap, increasing its tightness sufficiently to drive the lower jaw upward into the base of the skull. The upward force into the skull base, then, may have caused the fracturing and subsequent brain damage.

The brain damage was concentrated at the critical brain stem region where the spinal cord effectively “plugs into” the base of the brain. Damage in that region is usually instantly fatal.

 

How Helmets Can Kill1. Impact to the lower face bar is transmitted via the jaw to the skull.

2. The chin strap forces the jawbone upward.

3. The brain stem is severed.

The Helmet RotatesThis pattern of death emerged after four years of research.

 

Were our findings only present by chance in the sample of motorcyclists we studied? To find out, we performed a second study of 988 brains from autopsies performed on road accident victims. These 988 included 36 cases of unequivocal brain stem injury. The proportion of motorcyclists in that series was double the expected figure, and of the 15 motorcyclists, 13 were known to have been wearing helmets at impact and 11 had been wearing full-face helmets. Furthermore, the principal impact point was the chin bar in one of the bikers.

These findings strengthened the possibility that a blow to a rigid chin bar could be transferred via the chin strap to the lower jaw and then to the skull base, with fatal consequences to the fragile brain stem. If this were so, then how could it be prevented? In collaboration with engineering scientists and computer-aided-design (CAD) experts, we devised a series of solutions. Essentially, they involved the incorporation of an energy absorber into the chin bar of a full-face helmet. This would reduce the impact energy transmitted to the brain stem and, hopefully, transfer a potentially fatal impact victim into the survivable range. The wheels of change in altering safety designs move excruciatingly slow, the the full-face helmet with a soft, pliable chin bar extension may be a suitable alternative.

Let’s face it: A motorcyclist’s helmet should be worthy of the head upon which it rests.

Rodney D. Cooter, M.D.

Dr. Rodney Cooter is currently the Staff Grader in Plastic Surgery at St. James University Hospital, Leeds, United Kingdom. He trained for five years at the Weapon’s Research Establishment in South Australia before completing a four-year training in engineering draftsmanship with Telecom Australia. He studied medicine at the University of Adelaide for six years before commencing surgical training. During his surgical training with the Australian Craniofacial Unit, developed an interest in the engineering aspects of injury to the head and face. In his doctoral thesis-Craniofacial Fracture Patterns-he examined the effects of helmets on injury patterns. This article follows that intensive study.

 

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