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Haemorrhages from Head Injuries

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Haemorrhages from Head Injuries HAEMORRHAGES FROM HEAD INJURIES Hunterian Lecture delivered at the Royal College of Surgeons of England on 9th June 1955 by Milroy Paul, F.R.C.S. Professor of Surgery, University of Ceylon MY COUNTRYMEN HAVE been enrolled as members of this College for over seventy years now, and our long connection with the College greatly increases our appreciation of the privilege accorded me of delivering this Hunterian Lecture. INTRODUCTION My interest in head injuries dates from the time when, as a medical student, I read and re-read Wilfred Trotter's chapter on " The Scalp, Skull and Brain" in Choyce's System of Surgery (1923). The clarity of Trotter's descriptions and the brilliance of his conceptions of the genesis of head injuries made a deep impression on me. The haemorrhages of head injuries are easy to observe, and I became aware that there were some discrepancies between the features of these haemorrhages as I observed them, and as they are described in standard works on surgery. This stimulated me to observe these haemorrhages more closely, and to extend the observations which I could make in the wards and on the operating table, to the more complete examinations which are possible at autopsy. The many distinctive features characterising the haemorrhages from head injuries should have led to recognition of the factors controlling their onset and progress, but this expectation has not been realised, and there is still much that is not known in regard to the mechanics of these haemor- rhages. This study of the haemorrhages from head injuries is an inquiry into their origins, and of their modes of progress and of arrest. It is based on observations made of these haemorrhages in the course of a practice as a general surgeon over a period of 28 years. Questions which were deemed to be worthy of fuller inquiry, were investigated during the last four years by experimental work on the cadaver, and by detailed observa- tions of every case of head injury at the Colombo Hospitals to which I could get access during this period. THE SCALP HAEMORRHAGES The subcutaneous haematoma The subcutaneous haematoma is described in textbooks on surgery as the lesion which establishes that blood will not extravasate into the thick- ness of the scalp, but the significance of the lesion as an accurate mark of 69 MILROY PAUL the site of a violent impact on the head is not given the attention it ought to have. A violent impact on the head usually leaves no external mark, or causes a lacerated wound of the scalp at the site of the impact, but when it occasionally results in a subcutaneous haematoma, the lesion is likely to be missed if it is not looked for in a good light after the scalp has been shaved. The small circle of slightly raised, plum coloured skin is only seen in these conditions. The shape of the lesion proves that it was caused by violent compression of the scalp between the skull and the surface of impact, and the circular lesion is the result of extravasation of blood into the area of imprisoned scalp after its release from compression. Blood cannot extravasate beyond this area into the uninjured thickness of the scalp bordering the lesion. The lesion is consequently an accurate mark of the site of an impact, and its detection is particularly valuable in cases of extra dural haemorrhage where the clot is always below the site of the impact. It is also of some service for assessing the sites of contre coup injuries, and it may be important in medico-legal investigations. Sub-epicranial haemorrhage A sub-epicranial haemorrhage is described as a pool of blood on which the scalp floats. When fully developed it extends from the superior curved line on the occipital bone over the whole of the vault down into the interstitial tissues of the upper eyelids in front. This is the description given in every textbook on surgery (Rose and Carless (1952), Romanis and Mitchiner (1952)), although it relates to a lesion so rarely encountered in this form, that there would be many surgeons like myself, who have yet to see a fully developed case of this kind. The sub-epicranial haemorrhage is, however, a very common lesion in cases of head injury, but it differs markedly in characteristics from the haemorrhage as it is described in textbooks. In cases coming to autopsy I have found a sub-epicranial haemorrhage in everycase in which there were gross intracranial lesions. This sub-epicranial haemorrhage of every- day experience has not been described by writers on head injuries (Rose and Carless (1952), Romanis and Mitchiner (1952)), and the surgical and medico-legal implications of this haemorrhage have consequently not been appreciated. The lesion is to be observed in almost every severe head injury case. When the scalp is reflected off the skull at an autopsy, the sub-epicranial haemorrhage is displayed as two extensive sheets of extravasated blood, one coating the inner surface of the epicranial layer of the scalp, and the other coating the outer surface of the pericranium. There is no pool of liquid blood. Replacement of the scalp on the skull will demonstrate that the two coats of extravasated blood cover identical areas, and that they have been created by bisection of a single sheet of blood extravasated 70 HAEMORRHAGES FROM HEAD INJURIES in the sub-epicranial space. In any individual case there is in essence only one sheet of blood, and in cases in which the site of impact is marked by a lacerated scalp wound or by a subcutaneous haematoma, this mark will be at the centre of the sub-epicranial sheet of blood. The sub-epicranial sheet of blood gives no external evidence of its presence, and it is not seen till the scalp has been reflected off the skull. It gives evidence not only of a violent impact, but also of the site of the impact. The epicranial aponeurosis is connected by very numerous strands of connective tissue uniting it with the pericranium over the vault of the skull and with the temporal fascia on the sides of the skull. Extravasation of blood into the sub-epicranial space would be resisted by this forest of close set, short, connective tissue bands, and the collection of a pool of blood in the sub-epicranial space would not be possible if these bands were unbroken. The only blood vessels traversing the sub-epicranial space are a few emissary veins, and the invariable centering of the sub-epicranial sheet of blood on the site of impact, and not on the sites of these emissary veins, is evidence that the blood had extravasated from other sources. The blood vessels of the scalp lie in immediate contact with the epicranial aponeurosis, and violent bruising of the scalp at the point of impact can cause oozing of blood through the epicranial aponeurosis into the sub- epicranial space, although it cannot cause extravasation of blood into the thickness of the scalp, and blood from this source can then spread widely in the looser tissue spaces of the sub-aponeurotic space. Sub-epicranial haemorrhage is as constant in the head injuries of the new born infant as it is in the older age groups. In a series of autopsies on new born infants I found this extensive sheet of blood in the sub-epicranial space in every case in which there were gross intracranial lesions (Fig. 1). In most of these cases labour had been easy and without intravaginal manipulation. There could have been no violent impact on the skull in such cases and the mechanism must have been different. The squeezing of the head through the birth canal would have congested the vessels within the circle of scalp presenting in the lumen of the birth canal, and this congestion could have determined an oozing of blood through the epicranial sheet into the sub-epicranial space. As in adults there was no extravasation of blood into the thickness of the scalp. In most of the cases it was the sole herald of gross intracranial lesions. The haemorrhage into the interstitial tissues of the upper eyelids which would be the only visible manifestation of the commonly encountered sub-epicranial sheet of blood was found to be an independent lesion in many of the cases, as the " black eye," more often than not, involved the lower eyelids as well. The sub-epicranial sheet of blood can extend down on the side of the head over the temporal fascia and over the zygomatic arch on to the face, and when this occurs there is a swelling of the face extending from the zygomatic arch right down to and even below the mandible. 71 MILROY PAUL Fig. 1. The scalp haemorrhages of the new born. A sub-pericranial haematoma on the right side, and on the left side the two slices of a sub-epicranial haemorrhage as they would be viewed at a post mortem examination. The sub-pericranial haematomas The sub-pericranial haematoma is a common birth injury. The blood lies between the pericranium and the bone and it cannot extend beyond the margins of the bone on account of the firm blending of the pericranium with the intersutural fibrous tissue. In birth injury cases the haematoma is nearly always on one of the parietal bones. The details of the disposition of the haematoma on a parietal bone have not been previously described, although they are easy to observe (Fig. 1). The haematoma overlies that part of the parietal bone forming the roof of the vault, as distinct from the part of the parietal bone forming the side of the vault, and if it does extend on to the side of the vault, it should reach downwards as far as the superior curved line of the temporal fossa only, but as the temporal muscle in infants is an inconspicuous sheet on the parietal bone, the sub-pericranial haematoma in new born infants extends right down to the inferior margin of the parietal bone.
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