The brain is protected from injury by moderate degrees of violence applied to the head, by the dense and mobile scalp, the dome-like shape of the skull, the elasticity of its outer table and the buffer-like sutural membrane between the numerous bones of which it is composed, and the various internal osseous projections with the membranes attached to them, all of which tend to diminish vibrations and to disperse forces so that they expend themselves before they reach the brain. Further protection is provided by the water-bed of cerebro-spinal fluid, and by the external b.u.t.tresses formed by the zygomatic arch and the thick muscular pads related to it, as well as by the mobility of the skull upon the spine.
In all cases of head injury, the questions that dominate the whole clinical outlook are, whether the brain is directly damaged or not, and whether it is likely to become the seat of infection.
It is impossible to consider separately in their clinical aspects injuries of the cranium and injuries of the brain. It seldom happens that one is seriously damaged without the other suffering to a greater or less extent. Sometimes the skull suffers comparatively little, while the brain is severely damaged, but it is rare for a serious injury to the bone to be unaccompanied by definite brain lesions. In any case it is the damage to the brain, however slight, that gives to the injury its clinical importance. It is an old and a true saying that "no injury of the head is so trivial as to be despised or so serious as to be despaired of." Injuries at first sight apparently slight may prove fatal from haemorrhage or infection; on the other hand, recovery has followed injuries of great severity--for example, the famous "American crowbar case," in which a bar of iron three and a half feet long and one and a half inches thick pa.s.sed through the head, and yet the patient recovered.
It is convenient to consider the injuries of the brain before those of the skull.
TRAUMATIC LESIONS OF THE BRAIN
It is probable that in all cases of injury to the head in which a patient loses consciousness, there is some definite damage to the cerebral tissue. This takes the form of a greater or less degree of contusion or laceration, and the lesions are usually most severe and dangerous when the skull is fractured and fragments are driven in upon the brain, but they may exist--indeed they may be very extensive--in the absence of fracture.
Several degrees are recognised.
(1) Numerous minute _petechial haemorrhages_ may be found widely scattered throughout the brain substance, as a result of a diffused blow on the head, which has shaken up the brain and caused symptoms of cerebral shock or "concussion." We have found, on microscopic examination in such cases, in addition to these small extravasations, collections of colloid bodies, patches of miliary sclerosis, and chromatolysis and vacuolation of nerve-cells.[3]
[3] Miles, _Laboratory Reports, Royal College of Physicians, Edinburgh_, vol. iv.
(2) In more severe cases there are often several _visible areas of extravasation_, most commonly in the grey matter of the cortex (Fig.
184). These foci vary in size from a split-pea to a hazel-nut, and consist of a dark central zone of extravasated blood, surrounded by an area of "red softening" of the brain matter, beyond which are numerous minute capillary haemorrhages. These intra-cerebral lesions may be accompanied by an effusion of blood into the meshes of the arachno-pial membrane, and they may occur either at the part of the head struck, or at the opposite pole of the axis of percussion--the so-called point of _contre-coup_. The symptoms vary with the size and site of the extravasations. It is probable that the phenomena of "cerebral irritation" are to be explained by the occurrence of such haemorrhages widely scattered through the cerebral cortex. Effusions into the cortical motor areas give rise to irritation or paralysis of the muscles governed by the affected centres. Different forms of aphasia and interference with vision or with hearing follow implication of the centres governing these functions. In the pre-frontal and in the lower temporal convolutions no special symptoms seem to follow. When the haemorrhages are extensive and numerous, symptoms of compression may ensue, and these are aggravated when dema of the brain is superadded.
Localised haemorrhages also occur, although less frequently, in the crura cerebri, the pons, the floor of the fourth ventricle, and the cerebellum. In these situations they usually prove fatal by causing rapidly advancing coma and interference with the respiratory and cardiac centres. The temperature immediately rises to 106 or even 108 F., and a modified form of Cheyne-Stokes respiration is present.
(3) Still more gross lesions, in the form of distinct _lacerations_, are comparatively common at the tips of the frontal, temporal, and occipital lobes, on the surface of the cerebellum, and at the base of the brain. These are usually a.s.sociated with symptoms of compression in its most typical form, and as a rule prove fatal. The grey matter is torn, and extensive effusion of blood takes place into the brain substance, and on the surface, filling up the sulci, and distending the arachno-pial s.p.a.ce (Fig. 184). In a compound fracture, brain matter may be extruded through the opening in the skull.
(4) The extravasated blood may burst _into the lateral ventricles_, in which case the pulse becomes small and rapid--130, 160, or even 170. The respiration also is rapid--45 to 60--and greatly embarra.s.sed, and the temperature suddenly rises to 103 or 104 F., and continues to rise till death ensues.
(5) _Traumatic dema._--It is not uncommon for a diffuse dematous infiltration of the brain substance or of the arachno-pial membrane to take place in the vicinity of the injured portion of brain. This serous exude, on account of the natural adhesions of the arachno-pia, usually remains limited to the damaged area, but it may become generalised.
_Mechanism._--The explanation of these widespread haemorrhages is to be found, according to Duret, in the disturbance of the cerebro-spinal fluid which accompanies a severe blow on the head. This fluid not only surrounds the brain, but it also fills the ventricles, and permeates its substance in every direction in the peri-vascular and perilymphatic s.p.a.ces. As the brain tissue is incompressible, if an area of the skull is momentarily depressed by a localised blow, s.p.a.ce is provided for it by displacement of a quant.i.ty of cerebro-spinal fluid, which sets up a fluid wave, and this by hydrostatic pressure increases the tension of the fluid throughout the entire brain.
Vessels may be lacerated at any point, either by the flow of this wave or during the ebb which follows the recoil. Hence it is that the lesion is not always at the seat of impact, but may be at the opposite side of the skull or at other remote points.
[Ill.u.s.tration: FIG. 184.--Contusion and Laceration of Brain. Note limited lesion at point of impact on left side, and more extensive damage at point of _contre-coup_ on right.
(After Sir Jonathan Hutchinson.)]
_Repair._--As the disintegrated brain matter is replaced by cicatricial tissue, neither the nerve cells nor the fibres being regenerated, the loss of function of the parts destroyed is usually permanent. A localised extravasation of blood may become encapsulated, and const.i.tute a "haemorrhagic cyst." We have experimentally confirmed Duret"s observations and agree with his conclusions.
CLINICAL MANIFESTATIONS OF INJURIES TO THE BRAIN
For convenience, the clinical manifestations of cerebral injury are usually described under the terms "concussion," "cerebral irritation,"
and "compression," but no precise pathological significance attaches to these terms, they are essentially clinical. As the conditions so described do not occur as independent ent.i.ties and may overlap or merge into one another their differentiation is more or less arbitrary, and cases are frequently met with that do not run the course characteristic of any of these groups.
#Concussion of the Brain or Cerebral Shock.#--The symptoms a.s.sociated with concussion of the brain are to all intents and purposes those of surgical shock (Volume I., p. 250), the activity of the vital centres being disturbed by violence acting directly upon the brain tissue instead of by impulses transmitted to it by way of the afferent nerves. Various theories have been put forward to account for the depression of the vital functions in concussion. According to Duret, with whose views we agree, the wave of cerebro-spinal fluid set in motion by the impact of the blow on the skull, pa.s.ses, both in the ventricles and in the sub-arachnoid s.p.a.ce, towards the base, where it impinges upon the pons and medulla, stimulating the restiform bodies and so inducing a fall in the blood pressure and a profound anaemia of the brain. The disturbance of the cerebro-spinal fluid may at the same time produce the microscopic lesions in the brain tissues described on p. 341.
The symptoms of shock may be the only evidence of injury, or they may be superadded to those of fracture of the skull, or laceration of the brain.
The _clinical features_ vary according to the severity of the violence. In the slightest cases the patient does not lose consciousness, but merely feels giddy, faint, and dazed for a few seconds. His mind is confused, but he rapidly recovers, and, perhaps after vomiting, feels quite well again, save for a slight shakiness in his limbs.
In more severe cases, immediately on receiving the blow the patient falls to the ground unconscious. Sometimes he suffers from a general tetanic seizure a.s.sociated with arrest of respiration, which is usually of short duration and is frequently overlooked, but may prove fatal. The pulse is slow, small, and feeble, and is sometimes irregular in force and frequency. The respirations are short, shallow, slow, and frequently sighing in character. The temperature falls to 97 F., or even lower. The skin is cold and pallid and covered with clammy sweat, and the features are pinched and pale.
In uncomplicated cases the pupils are usually equal, moderately dilated, and react sluggishly to light. The patient can be partially roused by shouting or by other forms of external stimulation, but he soon subsides again into a lethargic condition. Although voluntary movement and the deep reflexes are abolished, there is no true muscular paralysis.
After a period, varying from a few minutes to several hours, he rallies, the first evidence often being vomiting, which is usually repeated. Sometimes reaction is ushered in by a mild epileptiform seizure. He then turns on his side, the face becomes flushed, and gradually the symptoms pa.s.s off and consciousness returns. The temperature rises to 99 or 100 F., and in some cases remains elevated for a few days. In most cases it falls again to 97 or 97.5, and remains persistently subnormal for one or two weeks. During reaction the pulse becomes quick and bounding, but after a few hours it again becomes slow, and usually remains abnormally slow (40 to 60) for ten or fourteen days. There is sometimes a tendency to constipation, and for the bladder to become distended, although he has no difficulty in pa.s.sing water. Very commonly the patient complains of pain in the head for some days after the return of consciousness.
Children often sleep a great deal during the first few days, but sometimes they are very fretful.
In cases complicated by gross brain lesions the symptoms of concussion may imperceptibly merge into those of compression or there may be a "lucid interval" of some hours duration.
_After-Effects of Concussion._--The majority of patients recover completely. A number complain for a time of headache, languor, muscular weakness, and incapacity for sustained effort--_traumatic neurasthenia_. Sometimes there is a condition of mental instability, the patient is easily excited, and is unduly affected by alcohol or other stimulants. Occasionally there is permanent mental impairment.
It is not uncommon to find that the patient has entirely forgotten the circ.u.mstances of the injury and of the events which immediately preceded it. In some instances the memory is permanently impaired. On the other hand, it has occurred that a patient, after concussion, has recovered his memory of a foreign language long since forgotten.
As it is never possible to determine the precise extent of the damage to the brain, the immediate prognosis, even in the mildest cases of concussion, should always be guarded. If the patient has been actually unconscious, the condition should be looked upon as a serious one, and treated accordingly.
_Treatment._--The immediate treatment is the same as that of shock.
Absolute rest and quietness are called for. When the symptoms begin to pa.s.s off, the head should be raised on pillows to prevent congestion and to diminish the risk of bleeding from damaged blood vessels in the brain. The value of applying an ice-bag or Leiter"s tubes with a view to arresting haemorrhage inside the skull, is more than doubtful.
Lumbar puncture, venesection, or the application of leeches over the temple or behind the ear may be employed with benefit. The use of small doses of atropin and ergotin was recommended by von Bergmann.
The bowels should be thoroughly opened by calomel, croton oil, or Henry"s solution, and a light milk diet given. The patient is kept in a shaded room, and should be confined to bed for from fourteen to twenty-one days. It is often difficult to convince the patient of the necessity for such prolonged confinement, but the responsibility for curtailing it must rest upon him or his friends. Reading, conversation, and argument must be avoided to ensure absolute rest to the brain.
#Cerebral Irritation.#--In some cases of injury to the head--particularly of the anterior part and the parietal region--as the symptoms of concussion are pa.s.sing off, the patient begins to exhibit a peculiar train of symptoms, which was graphically described by Erichsen under the name of cerebral irritation. "The att.i.tude of the patient is peculiar, and most characteristic: he lies on one side and is curled up in a state of general flexion. The body is bent forwards and the knees are drawn up on the abdomen, the legs bent, the arms flexed, and the hands drawn in. He does not lie motionless, but is restless, and often, when irritated, tosses himself about. But, however restless he may be, he never stretches himself out nor a.s.sumes the supine position, but invariably maintains an att.i.tude of flexion.
The eyelids are firmly closed, and he resists violently every effort made to open them; if this be effected, the pupils will be found to be contracted. The surface is pale and cool, or even cold. The pulse is small, feeble, and slow, seldom above 70. The sphincters are not usually affected, and the patient will pa.s.s urine when the bladder requires to be emptied; there may, however, though rarely, be retention.
"The mental state is equally peculiar. Irritability of mind is the prevailing characteristic. The patient is unconscious, takes no heed of what pa.s.ses, unless called to in a loud tone of voice, when he shows signs of irritability of temper or frowns, turns away hastily, mutters indistinctly, and grinds his teeth. It appears as if the temper, as much as or more than the intellect, were affected in this condition. He sleeps without stertor.
"After a period varying from one to three weeks, the pulse improves in tone, the temperature of the body increases, the tendency to flexion subsides, and the patient lies stretched out. Irritability gives place to fatuity; there is less manifestation of temper, but more weakness of mind. Recovery is slow, but though delayed, may at length be perfect...."
The _treatment_ consists in keeping the patient quiet, in a darkened room, on much the same lines as for concussion.
#Compression of the Brain.#--This term is used clinically to denote the train of symptoms which follows a marked increase of the intra-cranial tension produced by such causes as haemorrhage, dema, the acc.u.mulation of inflammatory exudate, or the growth of tumours within the skull. The only pathological idea the term conveys is that there is more inside the skull than it can conveniently hold.
_Clinical Features._--The following description refers to compression due to haemorrhage within the skull as a result of injury. In a majority of such cases, the symptoms of compression supervene on those of concussion; in certain conditions, notably haemorrhage from the middle meningeal artery, there is an interval, during which the patient regains complete consciousness, in others the symptoms of concussion gradually and imperceptibly merge into those of compression. The rapidity of onset of the symptoms and their course and duration vary widely according to the nature and extent of the brain lesion. Death may occur in a few hours, or recovery may take place after the patient has been unconscious for several weeks.
The first symptoms are of an irritative character--dull pain in the head, restlessness, and hyper-sensitiveness to external stimuli. The face is suffused, and the pupils at first are usually contracted. The temperature falls to 97, or even to 95 F. Vomiting is not infrequent.
As the pressure increases, paralytic symptoms ensue. The patient gradually loses consciousness, and pa.s.ses into a condition of coma.
The face is cyanosed, and the distension of the veins of the eyelids furnishes an index of the severity of the intra-cranial venous stasis (Cushing). The pulse becomes slow, full, and bounding. The respiration is slow and deep, and eventually stertorous or snoring in character from paralysis of the soft palate, and the lips and cheeks are puffed out from paralysis of the muscles of these parts. The temperature, which at first falls to 97 or even 95 F., in the course of three or four hours usually rises (100.5 or 102.5 F.). If the temperature reaches 104 F., or higher, the condition usually proves fatal.
Sometimes it rises as high as 106 or 108 F.--_cerebral hyperpyrexia_ (Fig. 185). Retention of urine from paralysis of the bladder, and involuntary defecation from paralysis of the sphincter ani, are common.
[Ill.u.s.tration: FIG. 185.--Two Charts of Pyrexia in Head Injuries.]
During the progress of the symptoms there is frequently evidence of direct pressure upon definite cortical centres or cranial nerves, giving rise to _focal symptoms_. Particular groups of muscles on the side opposite to the lesion may first show spasmodic jerkings or spasms (unilateral monospasm), and later the same groups become paralysed (monoplegia). The paralysis frequently affects the whole of one side of the body (hemiplegia) and the oculo-motor nerve is often paralysed at the same time.
The pupils vary so widely in different cases that their condition does not form a reliable diagnostic sign. Perhaps it is most common for the pupil on the same side as the lesion to be contracted at first and later to become fully dilated, while that on the opposite side remains moderately dilated. As a rule, they are irresponsive to light.
Ophthalmoscopic examination shows swelling of the disc, and the vessels of the papilla are distended and tortuous.
In cases which go on to a fatal termination, the coma deepens and the muscular and sensory paralyses become general and complete. The vital centres in the medulla oblongata gradually become involved, and death results from paralysis of the respiratory centre. The fatal issue is often hastened by the onset of hypostatic pneumonia. Not infrequently a modified type of Cheyne-Stokes respiration is observed for some time before death ensues.
A similar train of symptoms may ensue in cases of head injury as a result of _pyogenic infection_ having given rise to meningitis or abscess with acc.u.mulation of inflammatory exudate.