Difficulties and dangers attendant on the process of trephining for brain abscess.
Failure to find the abscess is usually dependent on one of the following causes:—
(a) The abscess may be missed if the localizing features are misleading, if the abscess be small, and if the exploring instrument be passed in a faulty direction or to an insufficient depth.
(b) The abscess may be traversed but not tapped if unsuitable exploring instruments be used—an aspirating syringe, for instance, through which the thick pus will not pass. Even when suitable instruments are used, the attempt to evacuate the abscess may fail if the operator does not carry out what may be called a system of progressive exploration, that is to say, if he does not periodically open the blades of the evacuator (see [p. 266]).
(c) The abscess may be encountered but not penetrated if the surgeon has to deal with a chronic abscess, the wall of which is merely pushed aside by the advancing instrument (see chronic abscess of the brain, [p. 268]).
Complications arising during and after the evacuation of the abscess are as follows:—
1. Leaking into the pia-arachnoid and the development of general meningeal infection.
2. Perforation of the ventricular spaces.
3. Hæmorrhage.
4. Respiratory failure.