to the extradural abscess. More rarely the abscess is due to septic infection
of one of the pial veins of the temporal lobe or cerebellum. Infection by
this route, which is common in cases of acute middle ear suppuration, may
result hi multiple abscesses and meningitis.
Once it has formed, a brain abscess tends to expand at the expense of the
white matter, which has less vascularity than the grey. In the temporal lobe
an abscess spreads along the vessels towards the lateral ventricle.
Fig. 186. Abscess of left temporal lobe. Note that the abscess has ruptured into the left lateral ventricle.
A, Lateral ventricles.
Fig. 187. Cerebellar abscess. 1-1, indicates what would be the normal middle line of cerebellum and
pons—note the swelling of the cerebellar hemisphere containing abscess; 2, Opening made for drainage*
SYMPTOMS. A brain abscess may be divided clinically into four stages:
1. Initial. There may be an initial rigor, with headache, vomiting and
rise of temperature during the period of red softening. This stage lasts for
a few days and is usually preceded by stoppage of the aural discharge.
2. Latent. During the latent stage, of variable duration, there are no
marked symptoms, although the patient's mentality may change. He may