Pus may gather between a patient's skull and his dura as the result of: (1) The spread of infection from sepsis nearby. (2) Exposure of the bone as the result of an injury. (3) Metastatic spread from elsewhere in his body. If his abscess is large, he will be very ill with signs of raised intracranial pressure (impaired consciousness and pupillary changes) and localizing motor signs, usually on the other side of his body, but not always so. Locally, he may have a diffuse inflammatory oedematous swelling of his scalp over the lesion (Pott's puffy tumour). If his abscess is not so large, he will not be so ill, and may have no signs of raised intracranial pressure. Making burr holes should be one of your basic skills (63.5), so draining the pus should not be too difficult. With your limited imaging facilities your problem will be to diagnose that he has an extradural abscess, and to know where it is[md]Pott's puffy tumour is the most useful sign.
EXTRADURAL ABSCESS X-ray his skull.
If his abscess is secondary to osteitis, and there is a sequestrum, removing it will drain the abscess adequately.
If his extradural abscess is secondary to metastatic spread, drain it through a burr hole. Make this on the edge of the area of swelling on his skull, and nibble away his skull around it until the abscess is well drained.
Fig. 5-4 PUS IN THE ORBIT. A, some important infections around a patient's eye. B, pus spreading under his periosteum from his frontal sinus. C, pus spreading under his periosteum from his ethmoid sinus.
1, the lachrymal gland (dacryoadenitis). 2, the frontal sinus and anterior ethmoidal air cells (sinusitis). 3, the tear sac (dacryocystitis). 4, tarsal cysts. 5, styes (hordeola). 6, periostitis of the margin of the orbit. Styes and suppurating tarsal cysts can occur anywhere on the lids, and periostitis anywhere in the orbit. After Hamilton Bailey's Emergency Surgery, edited by HAF Dudley, Figs 187, 188, and 189. John Wright, with kind permission.