engorged, and the superficial layers of the
cortical grey matter may share in the process (_encephalitis_).

_Clinical features._--The earliest and most prominent symptom is
violent pain in the head, often referred to the frontal region, or, in
cases starting from middle ear disease, to the temporal region. This
is accompanied by a sudden rise of temperature, usually without an
antecedent rigor; the temperature remains persistently elevated (102 deg.
to 105 deg. F.), and the pulse is small, rapid, and irregular both in rate
and force. The patient, especially if a child, is extremely irritable,
all his sensations are hyper-acute, and he periodically utters a
peculiarly sharp, piercing cry.

Vomiting of the cerebral type--that is, unattended with nausea and not
related to the taking of food or to gastric disturbance--is common,
and persists through the illness. The bowels are usually constipated.
There is an increase in the number of leucocytes in the cerebro-spinal
fluid, and organisms also are found in the fluid. As this does not
occur in cerebral abscess, examination of the cerebro-spinal fluid may
be useful in differential diagnosis. There is a higher leucocytosis in
the blood in meningitis than in cerebral abscess.

When the inflammation is most marked over the cerebral hemisphere,
there may be paralysis of the side of the body opposite to the seat of
the original lesion; sometimes there is erratic rigidity of the limbs,
sometimes clonic spasms of groups of muscles. The superficial reflexes
disappear early on both sides; the abdominal reflexes being lost
sooner than the knee-jerks. In basal meningitis, temporary squinting
due to irritation of the ocular muscles, retraction of the head, and
an excessively high temperature are usually prominent features. The
pupils at first are equally contracted; later they become dilated and
fixed. Both optic discs are oedematous and swollen.

Gradually the patient becomes unconscious, shows signs of increasing
intra-cranial tension, slowing of the pulse, and laboured respiration,
and the condition almost always proves fatal within three or four
days.

_Treatment._--The treatment consists in removing the source of
infection when this is possible, but as a rule little can be done to
arrest the spread of the meningitis or to ward off its effects. In
cases resulting from a sub-dural abscess in relation to a compound
fracture, a sinus phlebitis, or an erosion of the tegmen tympani,