I regard venesection as a valuable means of reducing the intracranial pressure. It is mainly of use in those cases that hover between slight compression and the fully-developed condition. Venesection may therefore be regarded as of special advantage in those cases that show elevation of temperature to about 101° and there ‘mark time’. The ‘bleeding’ should be carried out after exposure of the median basilic, external jugular, or internal saphenous veins, preferably from the first-named site. The amount of blood to be withdrawn varies according to the individual circumstances of the case, but, in general, the escape of blood should be encouraged till the pulse becomes soft, frequent and compressible. On an average, the quantity of blood withdrawn varies from 10-20 ounces. The operation not infrequently turns the scale in favour of the patient. Venesection may also be carried out in combination with ‘decompression’ operations.
When applied to suitable cases and carried out with discrimination, venesection often tides the patient over the stage of ‘crisis’. The most careful observation is needed in estimating the quantity of blood to be withdrawn, the pulse, blood-pressure, respiration, and temperature affording an adequate guide.
Lumbar puncture.
In spite of the apparent advantages of this method, it must, I think, be acknowledged that lumbar puncture is of but little use in reducing the general intracranial pressure. Consequently, in spite of the fact that this procedure has been strongly recommended, experience shows that it is of little practical use. This statement, based on personal experience, is at variance with the opinion of some other surgeons. For instance, de Quènu reports 7 cases of fractured skull which were ‘cured’ by this treatment, one of them requiring to be punctured eight times. Lumbar puncture assists the diagnosis, but I am doubtful whether it improves the prognosis.
‘Decompression’ operations.
‘Decompression’ operations may be carried out over the cerebellar fossa or over the temporal region of the skull. In cerebellar decompression a suitable scalp-flap is turned down and the trephine applied over the centre of the exposed occipital bone. After the removal of the disk the wall of the cerebellar fossa is cut away with the craniectomy forceps, up to the line of the lateral sinus above, to the mastoid process in front, to the vicinity of the foramen magnum below, and almost up to the middle line on the inner side. The bulging dura mater is incised in a crucial manner, right up to the margins of the osseous gap, all meningeal vessels that cross the line proposed for dural section being under-run with a fully-curved needle threaded with catgut. A small drainage-tube is inserted between the dura and the cerebellum and brought out through the most dependent part of the scalp-flap. The flap is then sutured in position. The drainage-tube should be stitched to the skin and withdrawn twenty-four to forty-eight hours later, according to the progress of the case.
I have carried out this operation on several occasions, but in spite of some immediate improvement in the condition of the patient, the remote results have been so unsatisfactory that I have abandoned the operation entirely. The effect of this cerebellar decompression is too radical, the medullary centres strongly object to such heroic attempts at pressure relief.
Temporal decompression, more correctly known as the intermusculo-temporal decompression operation of Harvey Cushing, leads to very different results. Previous to dealing with the technique of the operation, it will be convenient to enumerate the advantages claimed for this method in general.
(1) The frequency with which the bony lesion occurs in the middle fossa of the skull.
(2) The fact that cerebral contusions are especially liable to involve the tip of the temporo-sphenoidal lobe.