The Surgery of the Skull and Brain

by Louis Bathe Rawling

In shape the clot is elliptical; in consistency it is either fluid or jelly-like. During the early stages of its formation it can be readily removed. Later on, it adheres to the dura mater, and, when removed, leaves that membrane rough and discoloured.

Some uncertainty exists as to the relative frequency with which the trunk and the two terminal branches are exposed to injury. There can be no doubt that the majority of cases in which typical clinical symptoms are present are such as evidence injury to the anterior terminal division; this is due to the anatomical relation of the clot to the motor cortex. Injury to the main trunk is of the rarest occurrence, for the foramen spinosum lies immediately anterior to the petro-sphenoidal suture, the course pursued by typical middle fossa fractures. I have seen one case only, and have read the accounts of two others, in which the foramen spinosum was directly implicated.

The attachment of the dura mater to the sides and base of the skull exercises a most important influence on the direction in which the blood spreads. Firmly adherent to the lesser wing of the sphenoid in front and to the summit of the petrous bone behind, the membrane intervening between these two regions is but loosely attached to, and readily stripped away from, the floor of the middle fossa. As the clot increases in size it exerts considerable mechanical pressure and tends to separate still further the dura from the bone. The anterior and posterior limitations compel the blood to extend first in the outward direction and then upwards towards the vertex of the skull.

Krönlein divides middle meningeal extravasations, according to their regional distribution, into three main groups:—

Temporo-parietal (the most common variety).

Parieto-occipital (rare).

Parieto-frontal (very rare).

Middle meningeal hæmorrhages yielding typical clinical symptoms are of infrequent occurrence, yet such extravasations are very commonly present in severe lesions of the skull. This is evidenced by the fact that middle meningeal hæmorrhage—of a greater or lesser degree—was found in 20 per cent. of all cases of fractured skull, and in 45 per cent. of those in which the middle fossa was involved. My experience is confirmed by Dwight and Nichols. For example, Dwight, in 149 autopsies, notes that middle meningeal hæmorrhage was existent in 49 cases (29 per cent.). He maintains further that the artery is injured in nearly every case in which the fracture, extending from vault to base or vice versa, involves the middle fossa of the skull. Nichols reports 11 cases in 32 autopsies (34 per cent.).

Symptomatology.

As the direct result of the blow the patient is ‘concussed’, remaining in that condition for a variable period of time, a matter of seconds, minutes, or hours, according to the nature of the associated damage to the bone and brain. In the most typical cases, the patient, on regaining consciousness, should recover—again for a variable period of time—complete control over mind and body, returning to work, walking home or visiting hospital or doctor. More usually, however, he remains slightly dazed, though recognizing his surroundings and capable of answering questions. In any case—unless the hæmorrhage is accompanied by grave cerebral lesion—there should be some attempt at recovery, some return to consciousness. The importance of this ‘lucid interval’ cannot be over-estimated. It should be noted, however, that this interval of consciousness is not of itself absolutely diagnostic of middle meningeal hæmorrhage—it ought to be associated with definite localizing symptoms of brain compression (see below). I have encountered several cases in which this lucid interval was present, and in which operative procedures were carried out in the anticipation of finding an extra-dural extravasation, only to find a subdural hæmorrhage. Such subdural hæmorrhages are not infrequently associated with a similar return to the conscious state, but are rarely—if ever—accompanied by the early development of symptoms of localized brain compression. In the event of doubt as to whether the surgeon has to deal with an extra or subdural extravasation lumbar puncture will probably clear up the diagnosis.