ood which has passed
into the ear from a scalp wound, or which has its origin in a
fracture of the wall of the external auditory meatus or a laceration
of the tympanic membrane, for blood escaping from a fracture of the
base. Under these conditions the blood is usually bright red, is not
accompanied by cerebro-spinal fluid, and the flow soon stops. It is on
record[4] that blood and cerebro-spinal fluid may escape along the
sheath of the acoustic nerve without the bone being broken.

[4] Miles, _Edinburgh Medical Journal_, 1895.

#Fracture of the posterior fossa# is produced by the same forms of
violence as cause fracture of the middle fossa; it is specially liable
to result if the patient falls on the feet or buttocks.

_Clinical Features._--Sometimes a comparatively limited fracture of
the occipital bone results, and in the course of a few days blood
infiltrates the scalp in the region of the occiput and mastoid, or may
pass down in the deeper planes of the neck. As a rule, however, there
is no immediate external evidence of fracture. The patient is
generally unconscious, and shows signs of injury to the pons and
medulla, causing interference with respiration, which soon proves
fatal. The rapidly fatal issue of these cases usually prevents the
manifestation of any injury to the posterior cranial nerves.

_Diagnosis of Basal Fractures._--In the diagnosis of fractures of the
base, reliance is to be placed chiefly upon: (1) the nature of the
injury; (2) the diffuse character of the cerebral symptoms; (3) the
evidence of injury to individual cranial nerves; (4) the occurrence of
persistent bleeding from the nose, mouth, or ear; (5) the
extravasation of blood under the conjunctiva or behind the mastoid
process; and (6) the presence of blood in the cerebro-spinal fluid
withdrawn by lumbar puncture. In rare cases the diagnosis is made
certain by the escape of cerebro-fluid or of brain matter from the
nose, mouth, or ear.

It must be admitted, however, that in a large proportion of cases
which end in recovery, the diagnosis of fracture of the base is little
more than a conjecture. The external evidence of damage to the bone is
so slight and so liable to be misleading, that little reliance can be
placed upon it. The associated cerebral and nervous symptoms also are
only presumptive evidence of fracture of the bone. In all cases,
however, in which there is reason to suspect that the base is
fractured, the patient should be