he accumulation of inflammatory exudate, or the growth of tumours
within the skull. The only pathological idea the term conveys is that
there is more inside the skull than it can conveniently hold.

_Clinical Features._--The following description refers to compression
due to haemorrhage within the skull as a result of injury. In a
majority of such cases, the symptoms of compression supervene on those
of concussion; in certain conditions, notably haemorrhage from the
middle meningeal artery, there is an interval, during which the
patient regains complete consciousness, in others the symptoms of
concussion gradually and imperceptibly merge into those of
compression. The rapidity of onset of the symptoms and their course
and duration vary widely according to the nature and extent of the
brain lesion. Death may occur in a few hours, or recovery may take
place after the patient has been unconscious for several weeks.

The first symptoms are of an irritative character--dull pain in the
head, restlessness, and hyper-sensitiveness to external stimuli. The
face is suffused, and the pupils at first are usually contracted. The
temperature falls to 97 deg., or even to 95 deg. F. Vomiting is not
infrequent.

As the pressure increases, paralytic symptoms ensue. The patient
gradually loses consciousness, and passes into a condition of coma.
The face is cyanosed, and the distension of the veins of the eyelids
furnishes an index of the severity of the intra-cranial venous stasis
(Cushing). The pulse becomes slow, full, and bounding. The respiration
is slow and deep, and eventually stertorous or snoring in character
from paralysis of the soft palate, and the lips and cheeks are puffed
out from paralysis of the muscles of these parts. The temperature,
which at first falls to 97 deg. or even 95 deg. F., in the course of three or
four hours usually rises (100.5 deg. or 102.5 deg. F.). If the temperature
reaches 104 deg. F., or higher, the condition usually proves fatal.
Sometimes it rises as high as 106 deg. or 108 deg. F.--_cerebral hyperpyrexia_
(Fig. 185). Retention of urine from paralysis of the bladder, and
involuntary defecation from paralysis of the sphincter ani, are
common.

[Illustration: FIG. 185.--Two Charts of Pyrexia in Head Injuries.]

During the progress of the symptoms there is frequently evidence of
direct pressure upon definite cortical centres or cranial nerves,
giving rise to _focal symptoms_. Particular groups of