CHAPTER XXX. SCALP AA^OUNDS. (Part 1)

CHAPTER XXX. SCALP AA^OUNDS. AYoiinding of the scalp is sueli a frequent and important compli- cation of fracture of the skull, that the management of these wounds is best considered before entering upon the subject of injury to the skull and brain. Fracture of the vault of the skull is usually accompanied by wounding of the scalp or, in other words, the fracture is compound; and the successful treatment of the wound will often determine whether or not infection will follow the injury, and hence is of the greatest importance. Surgical Anatomy of the Scalp. — The scalp is composed of five layers : 1. The skin. 2. The subcutaneous layer of fat. 3. The occipito-frontalis muscle and its aponeurosis. 4. The subaponeurotic connective tissue. 5. The pericranium. These layers individually and collectively are of considerable surgical importance and should be understood when treating wounds of this region. The skin of the scalp, the toughest and thickest in the entire body, is supplied with numerous hair fol- licles and sebaceous glands. The subcutaneous layer of fat has bundles of fibrous tissue passing through it in all directions, and, together with the skin, is firmly adherent to the aponeurosis of the occipito-frontalis which lies directly below it. The hair fol- licles of the skin extend down into the subcutaneous tissue, and in gaping wounds the bulbous ends of the follicles may be seen by everting the edges. The aponeurotic layer or galea is composed anteriorly, of the frontalis muscle, which is inserted into the skin, posteriorly, of the occipitalis muscle, which arises from the superior curved line of the occipital bone, and the aponeurotic tissue or tendon which extends between these two muscles and divides the scalp surgically into two layers; — the superficial and deep. 379 380 FRACTURES AND DISLOCATIONS Wounds which divide the aponeurotic layer Avill gape, while wounds which penetrate only to the galea will present approxi- mated edges. Transverse wounds dividing the galea usually gape more widely than wounds of the same depth running in an antero- posterior direction. The three superficial layers just named are loosely connected with the deeper structures by means of an areo- lar tissue which allows free motion of the upper layers over the skull. The layer of subaponeurotic connectiA^e tissue is of the greatest surgical importance since infections in this loose areolar tissue, following the lines of least resistance, may spread, and if not promptly and freely drained the entire calvarium may be covered by the infection and the scalp ^'floated" with pus. The pericranium is the deepest layer, covers the calvarium and acts as a modified periosteum. It differs from periosteum in other regions in the following respects : the pericranium does not re-form bone following loss of osseus tissue to the extent observed in peri- osteum elsewhere; the circulation is less free; and it may b,e stripped from the bone without causing any serious disturbance in the nutrition of the denuded osseous tissue. Where the pericran- ium crosses the sutures it is intimately connected with the inter- sutural connective tissue, though in other portions of flie skull it may be readily stripped from the bone. The scalp as a whole, together with the hair, affords an excellent protection to the skull and is richly supplied Avith blood vessels. The main portion of the circulation of the scalp runs in the subcutaneous connectiA^e tis- sue and in the skin itself, and its richness accounts for the re- markable reparatiA^e properties of the scalp, which are not equalled elscAvhere in the skin of the body except the face. The amount of fibrous tissue present in the layer in Avhich the blood vessels run accounts for the profuse and prolonged hemorrhage so common in scalp wounds. This fibrous tissue prcA^ents the vessels from clos- ing as they do elsewhere folloAving injury, and explains the diffi- culty so frequently experienced in catching and ligating A^essels in the scalp. The mobility of the scalp Avill often save the parts from wounding by alloAving them to give before the vulnerant body. Vessels of the Scalp. — In the frontal region Ave have the frontal branch of the ophthalmic artery AA-hich emerges from the inner angle of the orbit and anastomoses with its fellow of the opposite side and Avith the supraorbital artery. The supraorbital artery is SCALP WOUNDS 381 a branch of the ophthalmic, of larger size than the frontal. It emerges from the orbit through the supraorbital notch at the junction of the inner and middle thirds of the supraorbital ridge, and divides into superficial and deep branches anastomosing with the frontal and anterior branch of the superficial temporal artery. The side of the scalp is supplied by the superficial temporal, a branch of the external carotid artery, which may be palpated as it ascends just in front of the auricle. This artery divides into an anterior and posterior branch and anastomoses with the deep temporal arteries; the anterior branch of the superficial temporal anastomoses with the supraorbital, and the posterior branch anastomoses with the posterior auricular and occipital arteries. The deep temporal arteries are two branches of the internal maxil- lary; they supply the temporal fossa, anastomose with each other and with the superficial temporal and lachrymal arteries. The occipital and posterior auricular arteries, — branches of the ex- ternal carotid, — supply the posterior portion of the scalp as far forward as the ears, and anastomose with each other and the posterior branch of the superficial temporal artery. The occipital artery passes onto the scalp at a point about midway between the inion and the external auditory meatus and in this region is more or less exposed to injury ; when opened it may give rise to profuse hemorrhage. It may be temporarily controlled by compressing it against the skull on the proximal side of the wound. All of the arteries of the scalp may be temporarily controlled by the application of an elastic tourniquet about the head, which is kept in place until the main branches are secured with ligature. The arteries most likely to cause free hemorrhage are the occipital and superficial temporal, either of which may be controlled by digital pressure against the skull below the wound. The anastomosis be- tween the above named arteries is very free, and the size of the vessels is large for the region supplied; the result is that the blood supply to the scalp is great, and the vitality of the tissues correspondingly high. The veins of the scalp correspond to the arteries just named, though there are some differences which are worthy of surgical note. The supraorbital vein anastomoses with the cavernous sinus by means of the angular vein near the inner angle of the eye, and thus infection in the region of the forehead may be drained into the cavernous sinus as well as into the facial vein, which is the 382 FRACTURES AND DISLOCATIONS continuation of the supraorbital, corresponding: to the arterial arrangement in this region. The superior longitudinal sinus re- ceives blood from outside the skull by means of the vein which passes through the parietal foramen, and in like manner connection is established between the scalp and lateral sinuses through the mastoid and posterior condyloid veins. These anastomoses are of importance in showing the Avay in which infection may pass from the outer surface of the skull to the intracranial sinuses. The lymphatic vessels form a free anastomosis in the scalp from which are derived the main trunks which follow the course of the arteries. The anterior portion of the scalp is drained into the submaxillary glands; the temporal region and that portion of the scalp above it is drained into the superficial and deep parotid lym- phatic glands. That portion of the scalp lying behind a vertical line connecting the two external auditory meati is drained into the occipital and posterior auricular glands. The nerves of the scalp may be divided into sensory and motor. The sensors^ nerves are of cranial and cervical origin. The an- terior portion of the scalp is supplied by branches of the fifth cranial nerve and extends upward to about the middle of the vertex. The posterior portion of the scalp is supplied hy branches of the upper cervical nerves. The sensory nerves may cause con- siderable pain lasting over a long period of time if the}^ become caught in scar tissue and may necessitate operation to afford the patient relief. All the muscles of the scalp are supplied by the facial nerve ; the occipitalis muscle sometimes receives additional filaments from the occipitalis minor nerve. The upper branch of the "pes an- serinis, " supplying the frontalis, is the most frequently injured motor nerve in the scalp. Inability of the patient to wrinkle the corresponding half of the forehead should lead to a search for the divided ends of this nerve before a scalp wound of this region is closed. Pathology and Symptoms. — "Wounds of the scalp may be classi- fied as incised, punctured; lacerated and contused; the nature of the wound depending on the character of the vulnerant body and the degree of trauma causing the injury. In addition we may have a simple contusion without an opening or wound in the scalp, and although it cannot properly be considered as a scalp wound yet its importance requires consideration under this heading. Simple SCALP WOUNDS 383 contusion of the scalp is common and may lead to collections of blood or serum in any of the various layers of the scalp. When the collection of blood is in the movable layer of the scalp (i. e., above the galea) it will be found to be freely movable with the skin and quite circumscribed. When the fluid is below the galea it is not movable, is much more diffused and may present a cir- cumference of induration which, when palpated in connection with the softened centre of the effusion, gives one the sensation of a depressed fracture. Continued digital pressure on this margin of induration will usually cause the fluids to be displaced suffi- ciently to differentiate, but if this is not satisfactory a needle may be used or the parts incised. Effusions below the epicranium are rare except in infancy ; when they do occur they will be found limited to one cranial bone of the vault, since the fusion of the epicranium with the intersutural fibrous tissue stays the further spread of the blood. Birtli trauma and the free vascular connection between the epicranium and the skull in infancy accounts for the comparative frequency of such effusions (cephalhematomata) during that period. The incised' wound, strictly speaking, is caused by some object with a sharp or cutting edge, yet there is a distinction which must be made between a truly incised wound and an apparently incised wound which has been produced by some blunt instrument, such as a club. A scalp wound produced by a club may, to the inex- perienced, have all the characteristic appearances of an incision, though on closer inspection it will be found to have a slightly ragged and contused edge and the underlying structures will not be found divided as by a knife. The cause of wounds has an im- portant medico-legal significance, and when the attending surgeon is called upon to give testimony he should be aware of the close similarity existing between true incised wounds and those made by a dull instrument. The mechanism of the pseudo-incised wound has been likened to the splitting of a kid glove, struck with a cane while the leather is stretched across the knuckle. The punctured variety of wound in the scalp is produced by pointed instruments, and the fact that the depths of the wound are not easily inspected without exploratory incision accounts for the overlooking of injury to the underlying skull and brain in many instances. It should be remembered that the punctured wound has the traumatic energy distributed over a very small area and 384 FRACTURES AND DISLOCATIONS is therefore more likely to do damage to the underljdng structures. Laceration of the scalp may exist in all degrees, from a slight tear to a complete avulsion. The average scalp wound shows some degree of laceration and more or less contusion, so that for prac- tical purposes wounds presenting these features are best considered under one heading. The tissues of the scalp may be torn and bruised in various ways, and the degree of injury ranges from the most serious to the most trivial; the important question in each case — so far as the scalp itself is concerned — is, what portion of the tissues injured has been damaged beyond recovery? This question can only be answered by a careful examination of the wound and an estimation of the circulation remaining in the ragged, mashed and torn edges. Dirt, cinders, gravel, broken glass and various other materials may be ground into the wound and the surrounding scalp, and if allowed to remain will act as foreign infectious bodies within the tissues. Loose hair is a very common material found within the wound and when not removed is almost sure to be followed by suppuration. A common form of lacerated, contused scalp wound is one in which the blow causing the wound has resulted in the traumatic death of more or less tissue, which will ultimately slough out if not removed at the time of operation. When the edge of the wound shows slight laceration union can often be expected even if the lacerated edges are not trimmed away, but when the laceration is severe and the edges mashed, we may look for more or less sloughing if this tissue is not removed, regardless of the presence or absence of infection. "When the devitalized tissue is extensive it may become impossible to remove it and approximate the edges. Inflammatory reaction is much more pronounced in contused wounds than in simple incision or puncture. A type of injury frequently seen is one in which one side of the wound has been slid and separated from the underlying structures as the result of a glancing blow, and the pocket thus formed under the scalp often contains infectious "m^aterials which have been forced into the wound at the time of injury. Complications and Sequelae. — The complications may be grouped under three headings: hemorrhage, infections and conditions ac- companying fracture of the skull and brain injury. Late compli- cations or sequelae are painful scar, aneurism of the scalp; deform- SCALP WOUNDS 385 iug contractures of scar tissue, tumor formation in the scar (kel- oids and rarely malignancjO together with the late complications following brain injury. Treatment. — The treatment of these wounds will depend on the conditions present in each individual case and it will be impos- sible to formulate the routine to be followed in all instances. A scalp wound may be present without any evidence of injury to either skull or brain, the patient not having suffered the slightest concussion, while on the other hand the scalp wound may be a part of a serious condition in which the skull is fractured, the brain injured and the patient in extremis. These extremes to- gether with the intermediate conditions require the greatest acu- men and surgical judgment so that we may not subject the patient to unnecessary operation on the one hand, and also avoid the over- looking of serious complications on the other. There are, how- ever, some general principles which should be followed in the treatment of these wounds, though the relative importance of each will vary in different cases. They are as follows : 1. Control hemorrhage. 2. Prevent infection as far as possible. 3. Avoid the overlooking of complications especially of skull and brain. 4. Close the wound as far as may seem advisable, providing drainage when necessary. 1. Control of hemorrhage. — The nature and amount of hemor- rhage will depend upon the character of the wound and the vascular structures divided ; it may be arterial or venous, and may consist of a simple oozing or an active spurting. The hemorrhage may be surprisingly profuse, when some of the main arteries of the scalp are divided, and when such is the case the first step in treatment must be the control of this bleeding. "When the artery is accessible it should be secured with hemostats for the time being, until the scalp has been appropriately cleaned; if the hemorrhage consists of moderate or slight oozing it may be neglected during the process of cleansing. In some cases it may become necessary to further open the scalp to expose the bleeding artery. In the most profuse hemorrhages we may secure temporary hemostasis by pack- ing a gauze sponge into the wound and making firm pressure on it with the hand. In the case of hemorrhaore from a sino'le laro-e 386 FRACTURES AND DISLOCATIONS artery, such as the occipital or superficial temporal, we may com- press the vessel against the skull a short distance to the proximal side of the wound pending the proper securing and ligation of the bleeding end. In extreme cases an elastic bandage may be used to encircle the head so that it passes just above the brows and ears and in this manner all the large vessels of the scalp will be compressed against the skull. One of the most annoying forms of hemorrhage is that of a persistent oozing which continues even after the wound has been thoroughly prepared and is ready for the sutures. This oozing may come from the edge of the wound proper or it may come be- tween the layers of the scalp in cases where the injury has been produced by a glancing blow and one side of the wound has been separated from the underlying tissues by "sliding." Such oozing is not, as a rule, dangerous in itself but if allowed to continue after the wound has been closed, will result