Owing to the recent advances in cranio-cerebral surgery, especially with reference to the frequent adoption of decompression operations, it is advisable that the cases should be classified into two groups:—
1. Cases of hernial protrusion, including cephaloceles (see [Chapter I]), protrusions intentionally produced by the surgeon in a decompression operation, and those which follow after unsuccessful operations for tumour removal. It will be observed that, in all these cases, the projecting brain, though bulging through its osseous barrier, is still protected by a more or less normal scalp-covering.
2. Cases of hernia cerebri. Here, as the result of injury to scalp, bone, dura, and brain, the cerebral substance bulges through a deficiency in the vault and presents on the surface, uncovered by integument. Hernia cerebri can develop under non-infective conditions, the congested state of the bruised or lacerated brain bringing about that degree of intracranial tension which can only be relieved by the outward projection of the brain. Still it must be accepted that Hernia cerebri almost invariably implies some bacterial infection.
Hernial protrusions are dealt with elsewhere. Hernia cerebri requires some consideration. Its development, by reason of its usual bacterial agency, must always be regarded as of serious import. The congested brain bulges through the aperture in the skull and presents on the surface as a purple—sometimes black—fungating mass, bleeding freely, and associated with a considerable discharge of cerebro-spinal fluid, serum, and pus.
The effects produced by this condition vary according to the extent of the cerebritis, and the question of associated meningeal infection.
When associated with meningitis those symptoms which might result from the hernial protrusion are more or less obscured by those dependent on the meningeal infection. Under other circumstances, the symptoms vary according to the extent and position of the area involved. Thus, when the infection is limited to the surface of the brain in the immediate vicinity of the aperture in the bone, the patient may merely complain of some headache and present some symptoms of cerebral irritation. More usually, the infection spreads rapidly to the surrounding brain substance, and the patient evidences the most acute stage of cerebral irritation, passing thence rapidly into a stuporose, typhoid-like condition.
A
Fig. 86. A Case of Hernia cerebri. A, The abscess after removal (natural size), cut so as to show the thickness of capsule.