In message <
b9d00307-9bf8-447a...@googlegroups.com>
nh...@hotmail.com wrote:
[snip]
>
> What you describe is a standard test of the material and structural
> strength of a helmet, not a restriction of the circumstances in which
> it will operate. In circumstances other than where the limited weight
> and strength cannot protect against fatality, a helmet will provide
> some degree of protection. That will be in most head impacts and
> frequently to a significant extent, making the difference between
> fatal and severe, severe and moderate, etc.
What I would question in that paragraph of yours is what you mean by
"frequently to a significant extent"
Yes there is going to be a difference between head injuries sustained
with and without wearing a helmet, but the important question I would
wish to know the answer to is 'exactly what proportion of accidents
involving head injuries would benefit from the proposed protection?'
Many road accidents involve other major injuries as well, and in those
cases death might result from several different causes. I've previously
pointed out to research on the increased wearing of ski-helmets where
the frequency of fatal ski-accidents hasn't changed significantly, but
the attribution of cause of death attributed to a head injury has
reduced. Those skiers still died as a result of their injuries, but the
doctors chose to put the emphasis on other injuries as the cause of
death.
> That is important in brain injury since, depending on location, even
> limited or moderate damage can have a serious or devastating effect on
> physical/cognitive/sensory/motor functioning. Unlike flesh, bone and
> muscle damage, which can self-repair, and can be aided by medical and
> surgical intervention neocortical neurons don't have these
> repair/replacement mechanisms, and they don't replicate. The brain
> recovers from significant injury to only a limited extent mainly by
> locational rewiring.
OK I accept the biology of all of that, but it still becomes relevant at
to what frequency of cycle accidents involve such damage, where the
wearing of a helmet would offer a significant advantage to the wearer?
Clearly there are going to be some accidents where the impact is low
enough that head protection isn't necessary and other impacts that are
so high that no degree of added protection will be of value. So the
critical question is to understand how big is the window of opportunity
between those two extremes? If only a small proportion of accidents fall
into that window, then only a small proportion of cyclists involved
in accidents would be expected to benefit from wearing a helmet.
> That is why protection of the head is particularly important
The logical alternative to considering protection of the head would be
to accept the vulnerability of the brain and instead to consider if it
is possible to reduce the frequency of road accidents? After all given
the huge variation in the rates of cycling injuries experienced in
different locations within the UK, and in different countries within
Europe, isn't there much more value for individuals to be gained from
lowering the overall accident rate in the first place, than by
concentrating on trying to make accidents survivable?
>
> > Population studies seem to agree with that analysis, as they make no
> >
> > discernable difference in the real world, except to depress cycling
> >
> > rates.
> >
>
> There are no credible population studies to show that analysis. The
> size, time period and control and assessment parameters for such a
> study would make it exceedingly large, difficult and expensive and no
> study of the necessary scale has been done
On that I think we can agree, The available research data has many
flaws, both for case-controlled as well as for population studies making
it difficult to draw fine conclusions.