—As indicated above, the symptoms and signs of compression are practically identical, no matter what the compressing cause. When this cause acts instantly there is no time afforded for differentiation, but when it occurs slowly we note the following symptoms, and about in the order here presented: Irritability or restlessness; visceral disturbances; pain; intense cephalalgia; congestion of the face; narrow pupils; augmented pulse, often seen in the carotids. If compression occur more rapidly, torpor quickly succeeds erethism, after which patients vomit, have convulsions or at least convulsive motions, speech is disturbed, and stupor comes on, from which they neither awake nor can be awakened until the compression is relieved. All of these indications refer to involvement of the cortex, which is generally regarded as the seat of consciousness as well as of projection and imagination. During the night, of the senses produced by pressure upon the cortex only the automatic basal apparatus and that of the spinal cord continue in more or less disturbed operation. Of all the general functions consciousness vanishes first and returns among the last. When intracranial pressure has reached a certain point, epileptiform convulsions result, varying in intensity, affecting all the limbs, and terminating perhaps with rigidity. These form an expression of high pressure. Similar convulsions occur in various head wounds, explanation for which is the result of pressure, which, though not extensive, may produce alteration in the circulation, with its disastrous consequences. The later and constant evidences of compression, and those which in aggravated cases supervene at once, are reduction of pulse rate, due to the action of the pneumogastric, which suffers first an irritation and later a paralysis. The pulse becomes not only slackened but full; the respiration rate is correspondingly reduced, so that breathing during coma is deep, slow, and often stertorous. This feature of stertor is an expression of paralysis of the palatal and pharyngeal muscles, which flap, as it were, in the air current. Vomiting, which may occur before brain tension has risen high, does not occur in the most serious cases. Coma is absolute.

Along with these signs the most important other indications are the paralyses, which may consist of monoplegia, hemiplegia, or paralysis of individual muscle groups, according as pressure is made upon a limited area or upon an entire hemisphere. By the division of the cranial cavity by the falx and the tentorium it is divided into chambers, in any one of which pressure may be more manifest than in the others. Nevertheless a serious compressing cause will affect the tension of the cerebrospinal fluid and produce general expression of pressure. The pupils often vary, and responsiveness to light is occasionally noted. Nystagmus and ocular rotation may be occasionally seen. Choking of the optic disk is also a frequent phenomenon, to be recognized only by ophthalmoscopic examination. This is due to pressure in the subdural and subarachnoid prolongations along the optic nerve. In milder cases of chronic compression disturbances of vision are of very great clinical importance. These pertain especially to diagnosis of hydrocephalus and of brain tumors. When they occur immediately after injury and remain, they depend upon laceration or other severe injury of the optic nerve. Those which quickly disappear depend mainly upon pressure of blood, which is reabsorbed, while those which are later in their appearance depend upon later intracranial complications. A unilateral lesion of the optic nerve depends most often upon injuries to it within the optic canal. When the lesion is bilateral the cause lies deep. General paralysis may be of the type of hemiplegia, single or double—i. e., by “double” I mean paralysis of the entire voluntary musculature of the body, which necessarily implies serious and often fatal hemorrhage.

Prognosis.

—This depends in large degree upon the nature of the compressing cause and of the possibility of its removal. While the nature of the same may ordinarily be determined, how much can be accomplished by way of removal may often not be foretold before the operation at which this should be attempted. In every acute case it is desirable to make this attempt early, for high pressure, which may be borne for a short time, is fatal if continued. Compression to any serious degree is usually fatal. So soon as paralysis of circulatory and respiratory centres is apparent the beginning of the end is at hand. Another reason for hastening operation is that acute softening of brain tissue comes on promptly, as well as general cerebral edema, which has destroyed many a patient during the second to the fourth day after injury.

Treatment.

—The treatment of compression is summed up in one phrase—i. e., to remove the cause when possible. The only cases in which this rule may be safely disregarded are those where the attempt to remove the cause means more danger than to leave it unremoved. This is not true, however, in the ordinary cases of bone depression, meningeal hemorrhage, etc. Before operation, however, or as a substitute for it in cases of minor severity, it may be well to assist venous outflow by venesection, by which blood pressure is reduced. In these cases this may be done from the temporal veins or external jugulars, with the patient in the semi-upright position. Drastic purgatives may also be employed in order to utilize intestinal outpour as a stimulation to resorption of cerebrospinal fluid. The physiological action of cold (ice-bags) may also be secured for the purpose of contracting the cerebral arteries. But all these measures are only to be resorted to when there is uncertainty as to the wisdom of operating, since when operation is indicated it should be done at once, and should take precedence of everything else. This operation means ordinarily the procedure to which the now general term trephining has been, by common consent applied, and comprises any measure by which the skull is opened at a suitable place and the dura or the underlying cortex exposed to such extent as to permit removal of the compressing cause. Whether the opening be made with trephine (annular saw) or with the straight or revolving saw, with bone chisel, with bone forceps, or with anything else, is a matter of choice on the part of the operator. So, too, removal of the compressing cause should include the elevation of depressed bone, the removal of dislodged particles as well as of all foreign bodies, the cleaning out of blood clot, the checking of hemorrhage, and the closure of the wound, with or without drainage or counteropening at some other part of the skull, as may seem desirable in special cases. This entire procedure comes now under the name of trephining, and should in most instances be painstakingly followed.

The operative maneuvers will be discussed in another portion of this chapter.

INJURIES OF INTRACRANIAL VESSELS AND SINUSES.

Intracranial hemorrhages may occur—

(a) From internal sources through the broken bone or between it and the dura (extradural);