Flat bones like those of the skull differ from long ones: (1) They have little marrow between their diploe, so that when they are infected the condition is an osteitis, rather than an osteomyelitis. (2) Unlike long bones, which make much callus when they fracture, and an obvious involucrum and sequestra when they are infected, fractured flat bones make little callus; infected ones seldom sequestrate, and don't form an involucrum. When sequestra do form in the skull, it is usually because a burn has destroyed the blood supply to the outer diploe.
A patient with osteitis of the skull has pain (''headache'), combined with tenderness and swelling over the lesion which may be particularly marked. It may be secondary to:
A burn (common, 58.32), as when an epileptic falls into a fire and burns his head.
A head injury (63.7). Minimize the risk of osteitis by toileting his wound carefully. If it does occur, you may have to remove a dead piece of bone.
Frontal sinusitis (25.8). He presents with a persistent headache. The bone above his orbit is prominent and tender, and he may have a swelling of his scalp which may extend as far as his vertex. X-rays show thickening of his skull and enlargement of his frontal sinus.
Pyaemia causing metastatic lesions in his skull. The skull is very vascular and has no end arteries, so the infection will probably settle without the need for drainage.
An extradural abscess (5.4a). The pus under his skull is more important than the pus in it.
Septic thrombophlebitis of his scalp which has caused it to necrose and expose his underlying skull. This condition is seen in malnourished children, and is related in its pathology to cancrum oris (26.6). It is not a true osteitis, but is rather a loss of the outer periosteum leading to sequestration of the diploe.
OSTEITIS OF THE CRANIUM When you plan the incision, consider the arteries of the patient's scalp, and incise between them. For example, don't make a transverse incision in his temple which will divide his temporal artery. Split skin grafts will not take on bare skull, but they will take on granulations. So, if necessary, remove dead bone, apply saline dressings for a few days, and wait for granulations to form. See Figure 63-11 and Sections 57.3 and 58.32.
CAUTION ! (1) If a sequestrum is firmly anchored, use an osteotome and light taps from a heavy hammer[md]don't open his dura or injure his brain.
FOLLOWING FRONTAL SINUSITIS. If you cannot refer him, define the extent of his frontal sinus with X-rays. Shave the anterior 3 cm of his scalp. Make a long incision above his hairline from ear to ear, and reflect the skin of his forehead downwards as a flap, based on his supraorbital vessels.
Remove the anterior wall of his frontal sinus; try to curette away all its lining, so that no more fluid will form. If possible, try to establish drainage through into his nose. Insert drains through stab incisions above the outer end of each eyebrow. Lead them horizontally from the frontal region of the sinus through these incisions. Or, insert them below his inner eyebrows. Close the flap.