The general effects as produced by penetrating and perforating bullet-wounds of the skull and brain are depicted in [Fig. 88], and described in the text associated with that figure.
Injury to the brain.
Brain lesions vary ‘from a single track with small points of extravasation in neighbouring areas to a condition of hæmorrhagic pulp, which latter condition is the result of injury from the projectile associated with bleeding, often extensive, into neighbouring areas, disintegrating and pulping the brain-substance. These latter cases are generally fatal, and are accompanied not infrequently with meningeal and ventricular hæmorrhage’ (Bowlby).[59]
The worst degrees of brain-injury arise when the injury is inflicted at close range, more especially at the site of emergence of a perforating bullet, the damage to the soft parts being there magnified by the waves and vibrations set up by the bullet during its passage across the brain. In many cases also the brain is dashed as a whole against the opposing osseous barrier (laceration by contre-coup).
The general effects produced on the skull and brain by a perforating bullet of high velocity are shown in [Fig. 88].
Symptomatology.
It is unnecessary to enter into details with regard to the symptoms arising from bullet-wounds of the skull and brain, for they closely resemble those previously enumerated in the chapters dealing with fractures of the skull and injury to the brain. There are, however, a few special points to which attention should be directed.
1. External hæmorrhages are seldom profuse.
2. The escape of cerebro-spinal fluid is of infrequent occurrence, probably due to the fact that the apertures of entry and exit are blocked up with scalp, fragments of bone, and pulped and swollen brain.
3. Concussion and irritation are prominent symptoms, compression is rarely seen in its typical form. As Spencer[60] says, ‘The dominant feature is usually concussion. The extent of the paralysis depends on the region injured, and there is often at first extensive temporary paralysis from vibratory concussion of the brain substance suspending its functions over a wide area around the bullet-track.’ Cerebral irritation and Jacksonian fits are frequently observed.