Chapter XVIII: , on Blood Pressure.) (1)

CONTUSION OF THE BRAIN.

The condition of _shock (cerebral concussion)_, when of pure type, passes away with reasonable promptness, especially when aided by surgical treatment. _Anything which persists_ in the way of muscle paralysis, disturbance of function of nerves of special sense, or _other sign of importance_, indicates something more than mere vibratory disturbance: it implies mechanical lesion which could be perceived by the eye were the parts exposed, and constitutes the condition known as _contusion_. This implies the existence of trifling exudates, or hemorrhages, which lead not only to absorption but even cicatrization. _Contusion pure and simple_ differs from ordinary _laceration_ as a contusion elsewhere may differ from a wound. It cannot be separated, however, from conditions in which there are minute separations of continuity and actual lacerations. It may be divided into three postmortem forms--_general hyperemia_, with or without edema; _punctate_ or _miliary hemorrhages_; and _thrombosis of minute vessels_, which may occur separately or together. Moreover, there may exist similar lesions in the meninges, constituting _meningeal contusion_. Ordinarily minute vessels of the pia are ruptured and blood is effused in small and thin patches over various parts of the brain. The so-called _compression apoplexies_ of certain authors are inseparable from the conditions above described. Such minute blood clots are only to be distinguished upon very careful sectioning of the brain, and are found most often in the region of the medulla and along the floor of the fourth ventricle. They are probably caused by the forcing into the fourth from the lateral ventricles of the fluid contained in the latter.

=Symptoms.=--When the ordinary symptoms of shock, which follow all severe injuries to the head, especially when the deep lesions are not too severe, fail to disappear in a short time under proper treatment, and when new and irregular symptoms are superadded to those of shock alone, it is reasonable to suppose that the intracranial condition is one of contusion rather than of shock. When mental agitation changes into delirium, when the rapid, feeble pulse becomes stronger and slower, the respiration deeper, the limbs move in incoördinate ways, the speech disturbed from muscle incoördination, the patient selects wrong words, or when the mental condition becomes more serious and stupor or coma take place of the delirium, while external irritants have less and less effect, and when the pupils gradually enlarge while failing to respond to light, it may be said that the _condition of contusion is making itself apparent_. If along with muscle uncertainty there is also muscle spasm or rigidity, with fixation of the fingers in the athetoid position, the evidence to this effect is increasing. If with all this the thermometer fails to show that an active inflammatory condition--_i. e._, meningitis--is prevailing the diagnosis may be regarded as certain. Error may possibly arise when there are evidences of alcoholism. Coma following head injury ought not to be ascribed to the _alcoholic condition_ except by the strictest process of exclusion. Temperature alone will be of the greatest service in this direction, since in _alcoholism_ it is usually _subnormal_. In _apoplexy and non-traumatic hemorrhages_ it is also usually _subnormal at the commencement of the attack_, rising to normal, and remaining there if the patient recover, but _continuing to rise in cases where the prognosis is bad_.

=Treatment.=--The treatment of brain contusion should be managed largely in response to special symptoms. Physiological rest, attention to scalp wounds, fractures, etc., shaving of the scalp, application of ice to the head, with such stimulation to the heart as may be necessary in extreme cases by subcutaneous administration of adrenalin, atropine, etc., by local fomentations over the epigastrium, or by immersion in a hot bath when surroundings permit it--these in a general way constitute most of the methods of treatment in contusion. When only symptoms of diffuse and minute lacerations can be recognized the use of the trephine is impracticable except when indicated by some external marking--_i. e._, compound fracture or the like. When _localizing symptoms_ are present the trephine is, of course, indicated. When the skull injury is recognized as a basal fracture, venesection or the application of leeches behind the ears will be most serviceable. In every such case there is the greatest necessity for _regulating the excretions_ and preventing auto-intoxication. For this purpose diuretics and laxatives should be used, often in conjunction with intestinal antiseptics. The catheter should be employed whenever indicated by the condition of the bladder, which should be carefully watched. As the days go by, and patients lie more or less helpless and inert, the greatest care should be exercised for the prevention of bed-sores. When mental inertness, muscle rigidity, etc., fail to disappear, potassium iodide should be used internally.

BRAIN PRESSURE OR COMPRESSION.

That the cranial contents--brain, blood, lymph, and cerebrospinal fluid--completely fill the cranial cavity has been already amply shown, as well as that there is no room for anything in the shape of a foreign body without seriously affecting the equilibrium between the brain and the contents of the spinal canal. When, however, any foreign substance exerts pressure upon the brain the results are invariably the same, be this substance what it may, and _compression signs are always the same, no matter what the compressing cause_. Reduction in capacity of the cranial cavity (_i. e._, compression) may be produced--

FIG. 1.

FIG. 2.

FIG. 1. Compound Fracture of Cranium, with Depression; Fracture of Bones of Face; Extradural Clot from Rupture of Middle Meningeal Artery.

FIG. 2. Horizontal Section of same, showing Depressed Fracture of Bone. (Anger.)

C, extradural clot; D, laceration of brain substance, with extensive intracerebral clot; F, same condition produced by contrecoup. Punctate hemorrhages and minute lacerations at numerous points, characteristic of contusion of the brain.]

1. By reducing the dimensions of its enclosing walls (_e. g._, depressed fractures or by direct pressure);

2. By increase in the quantity of cerebrospinal fluid or of the volume of the brain, which latter may be produced by edema, by serous exudate, or by actual hypertrophy;

3. By foreign bodies, which may enter the skull from without;

4. By pathological conditions--collections of blood or pus, tumors, etc., which may be produced either from the brain substance, its containing bone or membranes, or its vessels.

In every one of these conditions the size and tension of the brain are affected. _The cerebrospinal fluid is mainly involved in acute not in chronic conditions._ A slow reduction of the diameters of the skull produces such slow alterations of pressure as to cause a minimum of disturbance. So far as compression from traumatic influences is concerned we distinguish mainly between compression--

1. By extravasation of blood (see Plate XLIII);

2. By fractures of the skull with depression, or by foreign bodies penetrating from without;

3. By products of acute infectious inflammation due to septic infection from without.

The result common to all of these is _increase of intracranial tension_, and its consequence is a less rapid flow of blood and an altered blood supply to the brain and its membranes.

Experiment has established that in compression of the brain cerebrospinal fluid is forced by pressure into the spinal canal, whose membranes are more elastic, and which thus help to accommodate it; it has been also established that compression of the brain by one-sixth of its volume, by any material, is fatal, and that much less is at least serious. That fractures with depression produce sometimes serious, at other times trifling, symptoms is due to the varying accommodation of the spinal canal. Both experiment and observation seem to confirm the view that consciousness pertains to the cortex as a whole, and that unconsciousness is an inhibitory or paralytic condition which is produced in compression.

_Temperature_ is a matter of great importance in studying compression and foretelling its consequences. Elevation of temperature is an early, continuous, and constant symptom in these cases. If temperature be subnormal and subsequently rise, prognosis is bad. Variations of temperature are more reliable guides than conditions of consciousness. As Phelps has remarked, in no condition except sunstroke is temperature so uniformly high as in cases of serious encephalic lesions.

=Symptoms.=--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);

(_b_) Beneath the dura, between or into the membranes (subdural);

(_c_) Into the brain substance proper or the ventricles (subcortical or intraventricular).

The vessels whose injuries are most often under consideration are the _meningeal arteries_, the _sinuses_, the _small vessels of the membranes_, and the _internal carotid_. The arteries, like the sinus walls, may be ruptured either by substances forced in from without or by sheer laceration. The _longitudinal sinus_ is most liable to injury from without. When this sinus is exposed, it may be dealt with either by suture if the wound be small, or by ligation, or by tamponing with prepared gauze. Hemorrhage from this source is ordinarily not difficult to check. Fatal air embolism has resulted through an opened sinus not properly plugged. The other sinuses are more rarely injured, as by gunshot wound, fracture of the base, etc. The sinuses have also been injured by compression of the skull during parturition. Bleeding from a sinus is usually indistinguishable from that from a meningeal artery, except that the former occurs more slowly.

=Injuries to the Middle Meningeal Artery.=--Injuries to the middle meningeal artery naturally occur in the immediate neighborhood of this vessel, which is not infrequently ruptured by contre-coup. The artery runs sometimes in a groove of the bone, sometimes in the dura, and sometimes entirely in the bone. The more it lies within the bone the more likely it is to be ruptured when this part of the skull is fissured. Basal fractures often follow the groove for this artery. The anterior branch is more often injured than the posterior. Extravasations from this source are more common than from all others combined, the amount of blood varying within wide limits. 240 Gm. of blood clot have been known to collect and the dura to be separated down to the base of the skull. I have repeatedly taken away a small teacupful of blood clot in such cases (Fig. 377 and Plate XLIII).

Compression following hemorrhage from the middle meningeal artery. (Helferich.)]

=Symptoms.=--The symptoms of this hemorrhage are those of compression, while extravasation may be rapid and quickly fatal, delayed for some time, or may take place in two stages, the first but slight and producing no coma. New clots are always dark and disk-shaped, thick in the middle, with a definite margin. As the clots become older they become more adherent and difficult to remove. The symptoms of meningeal hemorrhage consist of an interval of consciousness or lucidity after injury, followed by epileptic or spastic symptoms, alterations in the pupils and pulse, unconsciousness passing into coma, and stertorous respiration. There may or may not be external evidence of head injury. The character of the _paralysis_ (hemiplegia) may indicate that the clot is really upon the side opposite to that of the skull which shows evidence of injury. In this case arterial laceration is the result of _contre-coup_. According to the rapidity of the symptoms is the extent of the primary lesion. Meningeal hemorrhages involve immediately the motor area, which makes diagnosis all the easier.

=Injuries to the Carotid.=--Injuries to the carotid within the cranium are exceedingly rare. Still, it has been injured in basal fractures and penetrating wounds.

=Arteriovenous Aneurysm.=--Development of arteriovenous aneurysms after basal injuries is occasionally noted. They will occasionally give rise to pulsating exophthalmos. Pulsating tumors within the orbit which push the eye forward not infrequently occur after serious head injury. Of 77 cases collected by Rivington, 41 had a traumatic origin.

=Subdural Hemorrhages.=--Subdural hemorrhages are not infrequent in the skulls of the newborn, and constitute the so-called _apoplexia neonatorum_. They may occasion convulsions and paralyses of irregular type, while if the extravasations become infected multiple abscess may result.

In adults subdural hemorrhages are most commonly connected with brain lesions which have been already spoken of as contusions. They may be the starting points for pachymeningitis. Their most common results are disturbances of consciousness and mentality. Paralytic dementia follows in some of these cases. Extensive subdural hemorrhage may give a clinical picture corresponding to extradural. Disseminated minute ecchymoses constitute minute focal lesions, which are, however, usually so distributed as to confuse and prevent accurate diagnosis. Apoplexy or intraventricular hemorrhages, especially from the lenticulostriate artery (Charcot’s “artery of hemorrhage”), have until very recently never been regarded as warranting surgical interference. Of late, however, especially in the ingravescent or progressive forms, ligature of the common carotid has been of some service, though in order to render this effective ligation should be done early.

=Traumatic Intraventricular Hemorrhage.=--Traumatic intraventricular hemorrhage occurs in much the same way as meningeal, by contre-coup. Individuality of symptoms is lost in the general comatose condition of the patient, but when operation is performed, as it is usually best to perform it, if no extradural clot be found and if brain tension be evidently increased, the dura should be opened; after which, if no subdural clot be seen, the ventricles should be tapped with an exploring instrument. In this case, if blood be removed by aspiration, a knife should be passed directly into the ventricle, after which blood, if present, will promptly escape. Dennis was the first to diagnosticate the presence of intraventricular clot and to deliberately incise into it, and I have myself repeatedly imitated this procedure, both with and without success.

In every case in which superficial or cortical hemorrhage can be recognized--or even suspected--or intraventricular hemorrhage as well, one should insist upon exploration. This means trephining, with perhaps aspiration of the ventricular contents. Tapping of the ventricle is described under Treatment for Hydrocephalus, while trephining is described at the end of this chapter.

LACERATIONS AND INJURIES TO THE BRAIN SUBSTANCE.

These have been mentioned under _contusion of the brain_. They may be divided into those which occur with or without fracture of the cranial bones. The term contusion was first suggested by Dupuytren. The condition comprises all degrees of injury, from the most minute local disturbances to lesions involving the entire hemisphere. The milder forms show a sprinkling of punctate hemorrhages, numerous in the centre of the injured area, the surrounding tissue taking on a more or less diffuse tint, which fades out toward the periphery, discoloration being due to the imbibition of the coloring matter of the blood. In more extensive injuries clots as large as peas, or larger, are embedded at various points, each surrounded by its area of discoloration. When foreign bodies have been driven into the brain the tissue is also discolored, while various foreign materials may be met. In instances of great violence there may occur absolute rupture of brain tissue extending from cortex to ventricle.

=Prognosis.=--Prognosis depends in large degree upon escape from or occurrence of infection. In infected cases the principal dangers are from blood pressure and from later edema or acute softening as well as from meningitis. Brain lacerations may heal by cicatricial repair, but usually with some perversion of function.

The possibility of _cystic degeneration of large or small clots_ is one of great importance. (See Cysts of New Formation in Chapter XXVI, page 264.) A blood clot within the cranium which fails to resorb is essentially a hematoma, in whose interior softening and conversion into a cyst may easily occur. These cysts make room for themselves at the expense of surrounding brain tissue, and when located in the motor area give rise to localizing symptoms as well as to epileptic convulsions. They may be often diagnosticated with certainty after an accurate history of the case and a study of the phenomena which it presents. As they grow older their walls become firmer, and it is often possible to dissect them out.

That _foreign bodies may be encapsulated_ and remain without producing disturbance is now well known. This is particularly true of bullets. As a rule, however, though encapsulated, they produce symptoms like headache, vertigo, etc. (See Plate XLIII.)

=Symptoms.=--The general features of brain lacerations are those of _contusion_. So long as the disturbances are minute, even if multiple, or the foreign body small, compression symptoms are not produced, or at least in very incomplete degree. Minute diagnosis is not easily obtained. The most essential thing is to decide upon the question of operative interference. In the absence of distinctly localizing symptoms or other external markings it is not usually performed. Upon the other hand a lesion which can be localized is probably due to extravasation sufficiently large to be easily reached by opening the skull; and, unless there be other and sufficient reason to the contrary, this should be done (Fig. 378).

In many instances, however, contractures or paralyses of muscle groups occur later, and are followed by spastic conditions which may be permanent. More can be done in these cases by massage, by internal medication, perhaps with external counterirritation, than by distinctly surgical procedures. Tendoplastic or neuroplastic measures for their relief may also be considered. Both albuminuria and glycosuria are known to be the result of injuries herein described, as well as bulbar paralysis and disturbances of special senses. More immediate dangers after these head injuries are those of bronchopneumonia or hemorrhagic or edematous infiltration of the lower lobes of the lungs--conditions often spoken of as _hypostatic pneumonia_, much resembling those produced experimentally in bilateral division of the pneumogastrics. Some of them are produced by paralysis of the glottis, the result of which is incomplete closure, with aspiration of fluids and solids from the mouth, whose decomposition sets up an infection within the lungs, and is often referred to as _aspiration pneumonia_. Some form of pulmonary disturbance follows in perhaps one-third of the cases of the injuries above alluded to, and should be anticipated and prevented.

Bullet embedded in anterior fossa. (U. S. Army Med. Museum.)]

GUNSHOT WOUNDS OF THE HEAD.

These have already been extensively considered in a previous chapter, so that but little more need be said of them here. Such wounds in the scalp are likely to be followed by sloughing. So far as gunshot fractures of the skull are concerned, there is frequently a marked discrepancy between the wounds of the inner and outer tables, that last perforated by the bullet being almost splintered. Penetrating wounds of the cranium by Mauser and similar bullets are not necessarily fatal. Many men were shot through the head during the Cuban and South African wars and yet did not die as a result of the wound. (See Chapter XXII.)

=Treatment.=--So far as treatment is concerned, gunshot injuries of the skull necessitate trephining or exploration, for checking of hemorrhage, disinfection of the bullet track when possible, often for a counterdrainage opening with through drainage either by tube or gauze. The _bullet_, if it can be found, should be removed. In searching for it the old porcelain-tipped probe of Nélaton has almost completely given way to Fluhrer’s aluminum probe, which is larger and longer and when rightly directed will by slight weight usually glide gently along a bullet track, thus leading often to the missile, and at the same time indicating by its direction where the counteropening should be made. Two other methods of detecting bullets are now in vogue. Girdner, some years ago, invented a telephone probe, by which, so soon as the instrument touches the missile, a telephone circuit is completed and the operator with a telephone receiver applied over his own ear hears the tell-tale “click” indicating the fact. This has been further improved by the substitution of a bell or “buzzer,” which tells its own tale when the probe touches the bullet.

A still more ingenious application of electricity for the purpose is that afforded by Röntgen’s discovery, and during the American and English campaigns of the past few years skiagrams of skulls showing bullets in various locations have become quite common. (See Plate XIII., p. 229.)

PROLAPSUS AND HERNIA CEREBRI.

_Escape of brain matter beyond its normal level_ is not uncommon in connection with compound fractures or their sequels. It may be primary, escaping with the blood at the time of the accident, or secondary, occurring during the ensuing days. Any lesion of this kind in which the brain appears or can be handled is entitled to the term _prolapsus_, in contradistinction to _hernia_, which implies that, though escaping from the proper cavity, it is nevertheless covered by other textures--_e. g._, the dura or scalp.

The protrusion may vary in size from a small tumor to one the size of a fist. It is always the result of uncontrolled intracranial tension, and may be produced by hemorrhage, by serous imbibition, or as the result of brain abscess. When immediate it is of the first variety; when later, of the second or third. When abscess is present it usually delays protrusion, which is produced by degrees. Prolapse occurs through large openings, such as those made by gunshot wounds, the trephine, etc. Prolapse proper implies laceration of the dura. It pertains obviously to the convexity of the skull, occurring, however, in exceedingly rare cases into the orbit (Fig. 379).

Prolapsus cerebri. (Bryant.)]

=Prognosis.=--The prognosis is generally unfavorable. There is always risk of edema or infection, either of which may prove fatal.

Infiltration, gangrene, suppuration, or repair by granulation may so disfigure and disguise the real brain substance as to lead to _error of diagnosis_. It by no means follows that every tumor presenting through an opening in the skull is of this character. When gangrene and spontaneous separation occur, spontaneous recovery may follow, the stump being covered by granulations and finally roofed over by connective tissue.

=Treatment.=--Treatment in the primary cases should include the most rigid asepsis with removal of all foreign particles. Localized pressure does some good, especially in those cases where it can be tolerated. Signs of abscess should always be watched for, and deep exploration is often justified or indicated. While excision or cauterization are often heralded as successful, they are by no means without their dangers. Nevertheless in selected and suitable cases excision may be freely practised. Cases that admit of it should wear a protective shield properly molded to the part. Skin transplantation, or even osteoplastic repair of the defect, may give good results in favorable cases.

SEPTIC INFECTIONS WITHIN THE CRANIUM.

Under the general term _septic infection_ are included:

_A._ Abscess;

_B._ Thrombosis;

_C._ Sinus phlebitis;

_D._ Meningitis;

_E._ Encephalitis.

These are different manifestations of infection, the clinical picture differing according to the tissues and localities involved. For the production of these infectious conditions no special bacteria other than those already catalogued in Chapter III are comprehended. Their method of activity is there discussed at sufficient length, and we need here only consider the various _paths of infection_. These may lie along the _bloodvessels_, the _lymphvessels_, _nerve sheaths_, and prolongations of the _membranous sacs_ which extend from the cranial cavity proper.

The most common of all the paths of infection is afforded by the _middle ear_, especially when involved in a chronic suppurative lesion, which is by no means necessarily connected with a patulous tympanic membrane, and which may consequently be undiscovered, though in more or less constant activity.

A. =Abscess of the Brain.=--This may be _traumatic_ or _non-traumatic_. The former variety is most often due to the direct result of injury, infection displaying its consequences promptly or sometimes not until long periods have elapsed. The ordinary form occurs within the first two weeks, usually as an acute cortical abscess beneath a more or less compromised membrane, surrounded by a zone of red softening, and this by another of brain edema. The _chronic_ traumatic abscesses are less often cortical, but are deeper. They are marked by prolonged suppuration of the external wound, but may occur through some mechanism not understood. Only the chronic abscesses show _encapsulation_, the capsule partaking of the character of the pyophylactic membrane, elsewhere described. (See Chapter VIII.) It may cover a long period--to my personal knowledge at least nine years, while others have mentioned twenty and more. The _non-traumatic abscesses_ are in the main due to _middle-ear disease_. When the roof of the tympanum breaks down it is the middle fossa of the skull which is infected; when the posterior wall, naturally the posterior fossa. The most common result of perforation of the tympanic roof is involvement of the mastoid antrum or the sigmoid groove and sinus. In the former case we have temporosphenoidal abscess; in the latter, cerebellar, if any. Previous to actual perforation there is thinning of bone with thrombosis along the minute veins connected with the sinuses. When the dura is exposed by the carious process, granulation tissue often protects it against further inroads, while masses of the same projecting into the tympanum have been mistaken for prolapse. If the sigmoid groove be the site of the first disturbance, extradural abscess may form between the sinus and the remaining bone, the granulating process then involving the whole bony groove. Its later consequence is _sinus phlebitis_, _sinus thrombosis_, or _intradural infection_. If there be adhesion between the dura and the cortex we have actual brain ulceration without formation of a true abscess; but if once the perivascular sheaths have carried infection to the substance of the brain there is a rapid purulent disintegration of the same, and formation of a true subpial or deep abscess, which latter is in effect a purulent encephalitis. Macewen has shown how important it is not merely to evacuate such abscesses, but to eradicate the path of infection from the point of origin, which is rarely easy.

_Extradural pus_ may escape into the mastoid cells by erosion of their inner walls. Such pus may escape suddenly, and serious symptoms thus be mitigated. Even abscess of the bone may thus empty itself by the process of adhesion and pointing toward the surface. Pus from the mastoid cells may perforate the temporomaxillary joint or escape along the digastric groove and form deep cervical abscesses.

When the arachnoidal tissue is involved, both subdural and subarachnoidal spaces participate in the infection, and the brain floats upon a pus-bed rather than a water-bed. _Leptomeningitis_ under these circumstances becomes quickly diffused and fatal. Serous fluid may accumulate so quickly as to produce death by mere obstruction to the cerebral bloodvessels, while distention of the ventricles and an acute infectious internal hydrocephalus is possible. Leptomeningitis may be propagated wherever anatomical paths may carry it, even to the cauda equina and along the spinal nerve sheaths.

The pus within cerebral abscesses is often discolored, sometimes offensive. A greenish color is usually imparted by the Bacillus pyocyaneus, while the offensive odor comes mostly from the Bacillus coli. Around such an abscess is a zone of inflamed cerebral tissue. If within this zone a pyophylactic membrane is produced by condensation the abscess may become encapsulated and life be prolonged. When a capsule fails to form, the process being too acute or rapid, death is the speedy termination of such a case. These abscesses are generally single, but may be multiple. There is also a metastatic expression of abscess formation, seen in typical cases of pyemia, where numerous miliary abscesses are found within the brain. Pressure symptoms are less likely from abscess than from a tumor of the same bulk, while there is much greater liability to edema and sudden infection. Gradually extending paralysis implies pathological activity around the abscess. Large collections of pus are often met in the least vital parts of the brain, as in the frontal or temporosphenoidal lobes.

=Symptoms.=--Aside from causal indications (_e. g._, injury to the head, middle-ear disease, recent operations upon the air-containing cavities, etc.) the first symptoms may be slight. They consist usually of headache, often ascribed to cold or trifling injury, becoming exaggerated, rarely definitely located, radiating widely. In time it is spoken of as “excruciating,” and may be continuous or intermittent. Vomiting is not infrequent, rarely accompanied by nausea. Chills come on early in the history of the case, varying in intensity, duration, and frequency. The more frequent, the more likely is it that the abscess results from some general infection. Temperature is seldom much elevated; it is often subnormal. When exalted it is in proportion to the degree of meningeal involvement. If pressure symptoms become marked we get the usual slow pulse due to increased tension. After evacuation of pus pressure symptoms may subside, but temperature rise. Such discharge from the middle ear as may have been previously noted usually diminishes. A history of cessation of discharge and of increased pain and fever occurring at irregular intervals is very characteristic.

These patients seldom come under the surgeon’s notice until the condition is serious. If they are still conscious, pain is the dominating complaint. This may be aggravated by percussion over the affected region. Rigidity of the sternomastoid on the affected side is a sign of lesion of the sigmoid sinus. Pain elicited by deep pressure in the posterior cervical triangle is also significant. There is mental hebetude, with progressive failure of mental and physical power, as the stupor increases, or coma becomes marked.

_Abscess_ may be often distinguished from _infectious thrombosis_, as in the latter respirations are quickened and vomiting occurs when the patient is in the upright position.

_Vomiting accompanied by cephalalgia is always indicative of intracranial mischief._ If it be a special feature throughout the case it may indicate cerebellar lesion. Convulsions are also frequent, but rarely distinctive. They are the result in most cases of secondary irritation of motor areas. Paralysis is the consequence of destructive rather than of irritative lesions.

The ear should be examined, and the use of a probe may give much information.

_Brain abscess connected with middle-ear disease_ will usually be found in the temporosphenoidal lobe, but occasionally occurs beneath the tentorium, in the cerebellum. Many of these cases are connected with self-evident indications of purulent otitis media and mastoid disease, and operation for the latter has often to be combined with the recognition of and suitable treatment for brain abscess. The surgical treatment of mastoid disease will be discussed in separate paragraphs and under a separate heading. Whenever there is any reason to suspect the existence of pus within the cranium the operator should expose the dura by opening above the mastoid; or his operation may already have taken him as far as the sigmoid sinus, in which case, with the dental engine or with other bone-cutting instruments, he may much enlarge the field of operation and thus make access both to the sinus and to the brain itself. An extradural collection of pus may be found within the sinus or above it. Drops of pus may escape as the operator cleans away or even presses apart the granulations. He has often to decide upon further exploration, either to open the sinus expecting to find it filled with disintegrated blood clot and products of decomposition, or to open the dura proper, expose the cortex, and perhaps explore here with the aspirating needle for pus located more deeply. In those cases where evidences of brain abscess are more pronounced, and those of mastoiditis less so, the lateral region of the skull may be exposed and the cranium opened with a trephine before working downward and exposing the mastoid region. In not a few instances both operations are combined and the area of bone to be cut away is relatively large. Thus complete _tympanic eventration_, with removal of much of the mastoid, may be combined with trephining and opening of a brain abscess, or opening of the sinus, in which latter there may be found such a condition as to make it advisable to ligate the common jugular low in the neck, and irrigate from the sinus to the location of the ligature, where the vein is laid open, or even to pass a small swab upon the end of a flexible probe. Nothing can more predispose to typical pyemia than a breaking-down clot within a sinus or vein involved in thrombophlebitis.

_Temporosphenoidal abscess_ will often be indicated by the escape of pus through the dura, above the roof of the tympanum. Although such an abscess might be evacuated by enlarging the tympanic approach to it, it would ordinarily be much better to open the skull above the ear, and thus make free access and provision for drainage. In any part of such an operation when the dura has once been exposed its appearance should be carefully noted. The coarse of the pial vessels can usually be traced through it. Therefore when it is sufficiently opaque to prevent any appreciation of conditions beneath, or sufficiently distended, it may be opened.

When cerebellar abscess is suspected the trephine should be applied about midway between the tip of the mastoid and the external occipital protuberance (inion), _i. e._, one inch beneath Reed’s base-line and one and a half inches back of the mastoid. The instrument should here be used with care, as the occipital bone is of irregular and variable thinness. In a brain abscess which can be freely opened gauze packing will be found serviceable, even though its use necessitates the employment of secondary sutures or perhaps leaving the wound open in order to permit of its removal.

Localizing symptoms are only occasional in connection with cerebral abscess, because the majority of these lesions are located without the motor area. Pupillary alterations are indefinite. As an abscess enlarges the size of the pupil may increase. Infective thrombosis rarely affects the pupils, save that when located in the cavernous sinus it may produce ptosis. In _temporosphenoidal abscess_ pain is usually localized in or near the ear upon the same side. As the motor area becomes involved there is a gradual development of localizing phenomena, referred to the opposite side. _Facial paralysis_ is common in advanced destructive lesions in the mastoid and tympanum. When produced by cortical lesion it is rarely so pronounced as when by direct paralysis of the nerve. In _frontal abscess_ there are few localizing phenomena. Abscess in the _parietal region_ is most commonly of traumatic origin, and is to be suspected in accordance with external surface markings. _Occipital abscess_ is exceedingly rare, and cerebellar abscess furnishes few localizing symptoms. Its most prominent clinical features are retraction of the head and neck; slow, feeble pulse and respiration; subnormal temperature; violent yawning; rigidity of the masseters; slow speech; optic neuritis; vertigo and vomiting. If accompanied by thrombosis there is pain upon pressure in the upper part of the neck. In all of these cases _when abscess is near the surface there is more or less leptomeningitis_, which becomes diffuse at once when the abscess bursts. If meningitis be present we have high temperature without marked remissions, rapid pulse, and general irritability, rapidity of pulse indicating predominance of leptomeningitis over encephalitis, since the more marked the latter the slower the pulse. As distinguished from sinus thrombosis we have in the latter high temperature with marked remission, rapid and weak pulse, frequent chills, profuse sweats, and often symptoms of pulmonary infarct or diarrhea, with cervical and submastoid tenderness and involvement along the jugular vein upon the affected side. _If all three conditions be associated the symptoms of thrombosis usually prevail_, although there may be retraction of the head due to basilar meningitis. As between tumor and abscess we have in the former absence of explanation of infection, slow progress of symptoms, more definite localizing phenomena, progressive involvement of nerves, pronounced optic neuritis, absence of chill, and alternating periods of mitigation of symptoms. Temperature and pulse afford little help, save that subnormal temperature points rather to abscess.

=Prognosis.=--From every direction come statements that the tendency of cerebral abscess is invariably toward fatality. No matter what the cause, unless relief be promptly afforded, death is the sure result. Of the acute cases those not promptly operated usually die within a few weeks. The more chronic or prolonged cases rarely come under surgical treatment; most of those which do are the result of disease in or about the middle ear. Were it possible to early diagnosticate formation of these abscesses prognosis would be much more favorable. When seen before necessarily fatal complications have arisen, in instances where the position can be reasonably well determined, surgical attack is likely to give good results. After proper evacuation even complete mental and bodily recovery is possible. Anchoring of the brain by adhesions may leave a train of disquieting symptoms, which, however, are not so bad as fatality. Abscesses may remain for a long time encysted, and yet be a fruitful source of danger. Multiple abscesses may complicate both the diagnosis and the treatment and produce a condition beyond help.

The operative treatment of these cases will be discussed by itself.

B. =Sinus Thrombosis.=--The sinuses are predisposed to thrombosis by virtue of their size, inflexibility, shape, and the fact that they are not emptied during respiration, all of which tend to retard blood flow. If to these be added defect in the blood supply, then everything predisposes toward _marasmic thrombosis_. This occurs much less frequently than the infective form, is mostly confined to the longitudinal sinus, is noted mainly at the two extremes of life, and is often seen in cases of death following exhausting diarrhea in children. In the _marasmic form_ the clots are dense, firm, stratified, and non-adherent; they rarely occupy the whole caliber. In old cases the clots may be tunnelled sufficiently to permit reëstablishment of circulation. Their principal evil consequences are edema of the frontal lobes and serosanguineous effusion into the ventricles or orbits--in the latter case producing exophthalmos. Sometimes epistaxis is produced. Strabismus, tremor, muscle rigidity, or contractures are more often seen conjoined, especially in children, with convulsions, sometimes unilateral, and choked disk.

=Diagnosis.=--The diagnosis in adults is difficult, but in children, when convulsions occur after exhausting illness, with the signs just noted, marasmic thrombosis may ordinarily be diagnosticated.

_Infective thrombosis_, the other variety, is due exclusively to the invasion of pyogenic organisms. It is observed mostly in the basal sinuses; its origin is local, and it is always secondary to some external infection. Its most frequent cause is middle-ear disease; consequently the sigmoid sinus is the one most often involved. It may follow carbuncle, erysipelas, or cellulitis of the external parts, or nasal ulceration, as well as dental caries, suppuration of the tonsils, etc. Infection may be propagated by tissue continuity, or through the circulation.

=Symptoms.=--Infective thrombosis presents few distinctive symptoms. Local ischemia, perversion of function, extracranial edema are too vague. Headache is nearly always constant and vomiting is frequent; temperature runs high, with marked remissions; the pulse is small and rapid, and remains so even under an anesthetic. _Chills_ are frequent, of the pyemic type, and are followed by copious sweats. Should pulmonary infarct occur there will be typical thoracic signs, although at first physical examination may give negative results. Later, however, we get prune-juice expectoration, putrid sputum, etc. Cerebral function is disturbed late rather than early. The duration of the disease ordinarily is from two to four weeks. Should _meningitis_ complicate the case there is more violent headache, persistent high temperature, great excitement, muscle spasm, strabismus, delirium, and coma; if the sigmoid sinus be involved there is usually retraction of the head. Should leptomeningitis extend down the spine, complaint of girdle pains will be made.

=Differential Diagnosis.=--The two conditions which are most likely to be confused with sinus thrombosis are meningitis and brain abscess. In _thrombosis_ there are pain and tenderness over the mastoid, extending down the neck. Fever is high, pulse rapid, respiration not affected, rigidity not usually present. Chills are frequently followed by profuse perspiration. The general picture is one of sepsis and the typhoid state. There are no special eye symptoms. Death is finally due to pyemic processes. In _meningitis_ pain is an early, constant, and severe symptom. Headache is frontal or general, fever is not characteristic, pulse is rapid until the accumulation of pus causes slowness by pressure, breathing is short and rapid, and finally of the Cheyne-Stokes variety. Rigidity of the neck and back, with retraction of the head, is nearly always present, with spasmodic contractions or convulsions about the neck. Chills are not so pronounced, vomiting is almost invariably of the projectile type, optic neuritis is frequent, and the intellect is early impaired. In _brain abscess_ pain is at first localized and severe, extending and becoming excruciating. This increases on pressure, and does not disappear until relief is obtained or the patient becomes unconscious. Temperature is normal or subnormal until the abscess ruptures. The pulse is slow, as in compression from other causes; breathing is slow and stertorous. Rigidity and vomiting are like those of meningitis. Eye symptoms are almost always present, photophobia at first, later inequality of pupils, with dilatation on the affected side, optic neuritis and irregular movements of the eye and lids. Drowsiness, dizziness, and impaired intellect are features when the abscess is in the cerebellum. Death occurs in coma unless the case be complicated by meningitis.

We may also have _exophthalmos_ on one side or both, with conjunctival injection, edema of the lids, and disturbances of vision, due to thrombosis of the cavernous sinus and stasis in the ophthalmic vein. In thrombosis of one transverse sinus only the internal jugular on that side will carry less blood. So long as that on the other side is free it will take that which cannot pass through the obstructed one. Consequently the jugular on the other side will carry more. But if the contained clot extend so far that direct communication with the internal jugular is interfered with then the internal jugular of the affected side will be almost empty, while the external of the same side will be the more distended. When the eye is protruded and the frontal vein distended it is evident that the cavernous sinus on that side is involved. If the superficial veins of the scalp be distended it is the superior longitudinal sinus which is at fault. When the veins of the mastoid region are involved, we may locate the thrombus in the transverse sinus; when there are no localizing symptoms, it can only be said in a general way that thrombosis has occurred.

=Prognosis.=--Prognosis is always unfavorable, though recovery is not impossible. The therapeutics are in the main prophylactic. By actual physiological rest the possibility of pulmonary complications can be diminished. The treatment, aside from this, is purely operative, and will be discussed elsewhere.

C. =Sinus Phlebitis.=--This may be the result--

(_a_) Of thrombosis; or,

(_b_) The continuation of suppurative processes from neighboring
tissues.

=Symptoms.=--The symptoms are seldom diagnostic. Sinus phlebitis is often accompanied by meningitis, even encephalitis. The first symptom is usually severe headache, often localized, made worse by pressure. Anorexia with early mental disturbance and often delirium follows, with vomiting, restlessness, and mania, changing to stupor and coma. _Rigidity_ or spasm of _cervical muscles_, or of those of the extremities, followed by paralyses, is often seen. Evidences of _irritation of special nerves_, particularly the oculomotor or the vagus, are not rare. When pyemic symptoms occur they are vague and are most conspicuous in the lungs and liver. Taken in conjunction with aggravating brain symptoms they make prognosis unfavorable.

Symptoms will in large measure depend upon the sinus most involved. They are characteristic if this be the _cavernous_ sinus. There are disturbances in the eye on the same side, congestion of orbital veins, pain and photophobia, and, later, cloudiness of the cornea and edema with exophthalmos. Finally the pupil becomes paralyzed and dilated, the cornea loses its polish, the upper lid cannot be raised, and, if the case persists, the cornea ulcerates. Along with these local evidences there will be complaint of frontal pain, usually with paralysis of the hypoglossal nerve and consequent thickness of speech. When the _transverse_ sinus is involved there are, first, vagus irritation, then paralysis with paralytic sequences in the muscles of the jaw, the tongue, palate, pharynx, etc. Diaphragmatic motions are interfered with and the character of the respiration altered. As the trouble extends to the internal jugular we have further paralysis of accompanying nerves, especially of the hypoglossal. As the irritation extends down the vein there will be tenderness, rigidity, and often swelling. The local signs and symptoms vary obviously as the lesion extends from one sinus to the other, for when one cavernous sinus is involved the trouble nearly always extends to the other, and local symptoms are repeated upon the opposite side.

D. =Meningitis.=--The dura has a duplicate anatomical character. Its outer surface, having the structure of periosteum, functionates as such; its inner surface, being lined with endothelium, partakes of the nature of a true serous membrane. When the former texture is mainly at fault we have pachymeningitis externa, or endocranitis, which is rarely a primary, but usually a propagated lesion met with after injury or external infection. It may lead to infiltration with purulent products, and, if speedy exit for pus be not provided, to involvement of the pia within. _Extradural suppuration_ without external injury is very rare, but should there have been a subdural hemorrhage with external lesion the blood clot may become infected and break down. _Pachymeningitis externa_ is most common after chronic lesions of the cranial bones--_i. e._, caries and necrosis. _Symptoms_ are not characteristic and often not distinguishable. When chronic there will be local tenderness, evidence of the presence of pus, with focal symptoms.

=Treatment.=--The treatment is always surgical, save possibly in certain cases due to syphilis, where delay may be justifiable for the purpose of testing the action of antispecific drugs.

=Pachymeningitis Interna.=--Pachymeningitis interna is often confounded with chronic hydrocephalus. It is frequently the occasion of a firm, membranous exudate upon the internal surface of the dura, which forms in time a new membrane rich in small and extremely friable vessels, from which hemorrhages easily occur, thus giving rise to the condition of pachymeningitis hæmorrhagica. Trifling hemorrhages will produce little or no disturbance; when of greater extent they may give rise to localizing brain symptoms. These extravasations may absorb or undergo fluidification--_i. e._, produce localized or cystic collections of fluid. The condition sometimes occurs after other acute infections, especially pneumonia, pleurisy, typhoid, whooping-cough, etc. Recovery is possible, but usually at the expense of adhesions, which lead to subsequent complications.

The _symptoms of pachymeningitis hæmorrhagica_ are headache, which will increase in intensity with every new escape of blood, usually localized in the vertex, with more or less paralysis following each new extravasation. The final result may be atrophy. Absence of disturbance in the cranial nerves points to lesions in the convexity rather than basal or ventricular. In chronic cases there is optic neuritis, and toward the end coma, usually coming on slowly. Dennis has recommended trephining under these circumstances, and has practised it with great benefit.

=Treatment.=--The treatment should be in a large degree surgical, for little short of eradication will bring about the desired result.