Puncture._--In certain cases of cerebral tumour, and of
tuberculous meningitis associated with an excessive quantity of fluid
in the arachno-pial space, temporary relief of such symptoms of
increased intra-cranial tension as headache, vertigo, blindness, or
coma, has followed the withdrawal of from 30 to 40 c.cm. of the fluid.
Terrier and others have found this measure useful in relieving pain in
the head, delirium, and even coma, in cases of basal fracture.
Carriere has found it beneficial in some cases of uraemia. The quantity
withdrawn must not exceed 40 c.cm., lest the ventricles be emptied and
pressure be exerted directly on the basal ganglia (Tuffier). In a
number of cases sudden death has followed the withdrawal of
cerebro-spinal fluid.

This route is sometimes selected for the induction of spinal
anaesthesia, and for the injection of antitoxin in cases of tetanus.

HEAD INJURIES

The brain is protected from injury by moderate degrees of violence
applied to the head, by the dense and mobile scalp, the dome-like
shape of the skull, the elasticity of its outer table and the
buffer-like sutural membrane between the numerous bones of which it is
composed, and the various internal osseous projections with the
membranes attached to them, all of which tend to diminish vibrations
and to disperse forces so that they expend themselves before they
reach the brain. Further protection is provided by the water-bed of
cerebro-spinal fluid, and by the external buttresses formed by the
zygomatic arch and the thick muscular pads related to it, as well as
by the mobility of the skull upon the spine.

In all cases of head injury, the questions that dominate the whole
clinical outlook are, whether the brain is directly damaged or not,
and whether it is likely to become the seat of infection.

It is impossible to consider separately in their clinical aspects
injuries of the cranium and injuries of the brain. It seldom happens
that one is seriously damaged without the other suffering to a greater
or less extent. Sometimes the skull suffers comparatively little,
while the brain is severely damaged, but it is rare for a serious
injury to the bone to be unaccompanied by definite brain lesions. In
any case it is the damage to the brain, however slight, that gives to
the injury its clinical importance. It is an old and a true saying
that "no injury of the head is so trivial as to be despised or so
serious as to be despaired of." In