Closure of the dura and reposition of the flap.
Whether the tumour has been exposed and removed, is deemed irremovable, or has not been found, the dural flap should be approximated and carefully sutured in position. In many cases, however, this dural approximation is exceedingly difficult to accomplish, by reason of the outward bulging of the diseased or œdematous brain. This difficulty may be overcome by adopting one or more of the following methods:—
Elevation of the head, thus reducing the amount of blood in the brain.
Lumbar puncture, a method that presents some danger when the surgeon has to deal with a subtentorial tumour, but which bears in its train excellent results from the point of view of reduction of intracranial pressure. The danger arises from the fact that the sudden escape of cerebro-spinal fluid may cause the brain-stem to be engaged in the foramen magnum, with disastrous results on the medullary centres.
Ventricular puncture, when the ventricles are dilated. A blunt-pointed aspirating needle is introduced into the lateral ventricle through the most prominent portion of the exposed brain, and a sufficient quantity of cerebro-spinal fluid evacuated.
‘Milking’ the pia-arachnoid, the pia-arachnoid being pricked with a needle in several places and the contained fluid squeezed out.
Subtemporal decompression—the final resource. When all other measures fail, a subtemporal decompression may be conducted on the opposite side of the brain.
The dura should be accurately sutured with numerous interrupted silk sutures. It is very important that every precaution should be taken to prevent the continued escape of cerebro-spinal fluid, and, for this and other obvious reasons, it is necessary to avoid drainage whenever possible. If such a course should be necessary—by reason of hæmorrhage—a cigarette drain may be brought out at the most dependent and convenient angle of the dural flap, and through one of the trephine holes or gap purposely cut in the bone-flap.
In any case, the bone-flap is replaced, resting on its shelf and anchored by means of numerous deep sutures, each of which picks up the aponeurosis or muscle both along the upper border of the flap and the two downward vertical prolongations. These sutures will also control bleeding from the divided scalp-vessels. The tourniquet is removed, dressings applied, and the whole maintained firmly in position by a gauze bandage applied circumferentially. These dressings are supported by bandages and the patient sent back to bed.
If the tumour has been exposed by craniectomy, the gap in the skull will probably require protection. This procedure (see [Chapter VI]) can be carried out at the termination of the main operation or at a later date. This latter course is to be preferred.