63.7 Open head wounds

The first principle in an open head wound is that what may look like a simple scalp wound may have a tear in the dura underneath it. The dura forms an excellent barrier to infection, so that wounds which go through it are much more serious than those which do not. Even the most seemingly trivial head wound is potentially dangerous. If you neglect a wound of the dura, meningitis, a brain abscess or osteomyelitis may follow. X–rays are useful-much more so than in fractures of the base. So X–ray all but the most trivial open head injuries in search of: (1) An open fracture under a penetrating wound. (2) A depressed fracture needing elevation. (3) A spicule of bone going through the dura which needs to be removed. (4) A foreign body. If you suspect that any of these four things might be present, explore the patient’s scalp right down to the bone.

Figure 63.12: THE ANATOMY OF THE SCALP AND SOME IMPORTANT LESIONS. A patient’s epidermis (1) is separated by a fibro–fatty layer of dermis (2), from his strong fibrous galea (3). These three layers are firmly united to one another to form his scalp. Under his galea there is a potential space, his subgaleal space (4), which enables his scalp to slide over his pericranium (5). Under his pericranium lies his skull (6), his dura (7), his subdural space (S), his arachnoid (9) his subarachnoid space (10), and his brain (11). When you anaesthetize a patient’s scalp, inject the solution into the fibro-fatty layer, not under his galea. Blood or pus sometimes collects in the subgaleal space and spread through it. An extradural haematoma forms between the skull and dura, and a subdural one between the dura and the arachnoid.