Fatal Facts About Helmets
   A Neurosurgeon Speaks the Truth

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 rare 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 fatal 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 Kill:

1.  Impact  to the  lower  face  bar is  transmitted  via the jaw to   the skull.

2.  The  chin  strap  forces  the  jawbone  upward.  The  brain  stem is severed.

3. The Helmet  Rotates.  This 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 ma8y 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.  )