required are a scalpel, an Allis dissector, hæmostatic, dissecting, and toothed forceps, trephines of several sizes, a periosteum-elevator, a Hey saw, rongeur forceps, a bone-elevator, a dural separator, a tenaculum, small curved Hagedorn needles, and a needle-holder. Provide a sand pillow. The patient lies upon his back, the shoulders are a little raised, the sand pillow is placed under the neck, and his head is turned away from the side to be operated upon. The position of the surgeon is such that the patient's head is a little to his left. A large semilunar incision is made with the base down, which incision goes through the periosteum, and the flap is lifted. The bleeding vessels of the flap are caught with forceps. The pin of the trephine is projected beyond the crown and is set upon sound bone, the crown overhanging the line or edge of the fracture. A gutter is cut in the bone, the pin is withdrawn, and the trephining is completed. In going through the diploë bleeding is copious and the inner table feels very dense. Stop from time to time, clean out the gutter with the dissector, and try the bone with an elevator to see if it is loose. When the fragment is loose enough, pry it out and hand it to an assistant, who places it at once in a bowl of solution of corrosive sublimate (1 : 2000) kept warm by standing in a basin of water at 105°, or who puts it in warm carbolized towels or in warm normal saltsolution. The edges of the opening are rounded with a rongeur and the bone is elevated. Sometimes it may be necessary to remove splinters and fragments of bone. The dura is examined to see if injury exists, hemorrhage is arrested, the wound is cleansed, the button of bone is reintroduced, or some chips are cut from it and scattered upon the dura. The scalp is sutured and horse-hair drainage is employed for a day or two. Sterilized gauze dressings are put on, a rubber dam is laid over them, and a gauze bandage wet with bichloride-of-mercury solution is applied.

Technique of Brain-operations (after Horsley and Keen). -Always shave the scalp, and always antisepticize it. In localizations, mark out the fissure upon the scalp with an aniline pencil or with iodine. Have the patient semi-recumbent. Mark three points upon the bone with the centre-pin of the trephine before incising the scalp (both ends of the Rolandic fissure and the point at which the trephine will be applied). Make a semilunar flap three inches in diameter, with the base below. Control bleeding in the flap by forceps pressure. The one and a half inch trephine is used, but, if a smaller trephine is employed, the opening must be enlarged with a rongeur. Before enlarging the opening, separate the dura from the bone by a dural separator. As a rule, open the dura and examine the brain. The dura is lifted by rattoothed forceps and is opened with scissors along a line a quarter of an inch from the bone-edge. Hemorrhage is arrested by pressure and hot water or by passing a curved needle threaded with catgut around any bleeding vessel. In some cases packing must be left in or forceps must be kept on. In packing, never use more than one piece of gauze, so as to avoid leaving in a forgotten piece. Upon opening the dura, cerebro-spinal fluid flows out, the stream being increased with each expiration. Absence of pulsation of the brain points to tumor, and a livid color indicates subcortical growth. An old laceration is brownish. If the brain bulges through the opening, it means increased pressure (tumor, abscess, effusion into the ventricles, etc.). After opening the dura, employ no antiseptics except boiled water, especially when the surgeon intends using electricity to locate a centre. Remove any abnormal brain-tissue which is found. In electrifying the brain, faradism is employed of a strength about sufficient to move the thenar muscles when applied to them. After an aseptic cerebral operation, as a rule, do not drain. In many cases replace the bone, but not when the bone is

diseased, is infected, or is very compact, or if it is desired to alter pressure. The dura is sutured by a continuous catgut suture (Fig. 131); the scalp is sutured by interrupted silkworm gut (Fig. 132).

THE

FIG. 131.-Continuous Suture.

FIG. 132.-Interrupted Suture.

Operation for Mastoid Suppuration.-The instruments required in this operation are a scalpel, a gouge, a chisel, a mallet, curettes, a probe, a dissector, dissecting and hæmostatic forceps, and needles. Provide a sand-bag to place under the neck. An incision is made one-quarter of an inch. posterior to the auricle and down to the bone. The bone is bared and examined especially at a point in the line of the incision which is on a level with the roof of the meatus. The bone will usually be found softened. Gouge it away and thus open the mastoid antrum. This bone-opening is within the limits of Macewen's suprameatal triangle, a space bounded by the posterior root of the zygoma, the posterior bony wall of the meatus, and a line joining the two. If, in the adult, pus is not found, gouge downward and backward, but with great care, so as to avoid the lateral sinus. After evacuating the pus, scrape out the cavities with the curette, enlarge the opening between the mastoid and the middle ear with the gouge, turn the head toward the side operated upon, and irrigate the mastoid with corrosive-sublimate solution (1:2000); dust in iodoform, pack with iodoform gauze for a few days, and then introduce a silver drainage-tube. Treat the causative ear disease.

If mastoid suppuration has established abscess in the

temporo-sphenoidal lobe, trephine one and a quarter inches behind and one and a quarter inches above the middle of the external meatus (Barker's point), and search for pus as directed on p. 559. If abscess of the cerebellum exists, trephine below the line of the lateral sinus-that is, below a line running from the inion to a point on a horizontal line from the roof of the meatus, one inch posterior to the middle of the meatus. If infective sinus thrombosis exists, break into the lateral sinus through the mastoid opening and proceed as directed on p. 560.

XXIII. SURGERY OF THE SPINE.

Congenital Deformities.-Spina bifida, or hydrorrhachitis, is a congenital cystic tumor due to vertebral deficiency, permitting protrusion of the contents of the spinal canal in the median line. The laminæ or spines of one vertebra or of several vertebræ may be deficient, most frequently in the lumbo-sacral region. Meningocele is a protrusion of dura mater and arachnoid, the sac containing cerebro-spinal fluid, but no nerves and no cord-substance. Meningo-myelocele (the commonest form) is a protrusion of dura mater and arachnoid, the sac containing cerebro-spinal fluid, nerves, and cord-substance. The cord may spread out upon the sacwall or it may pass through the sac and re-enter the canal. Syringo-myelocele is great distention of the central canal, the sac-wall being formed of the thinned cord. A hydrorrhachis varies in size from that of a walnut to that of a child's head; it grows rapidly during the early weeks of life; it is usually sessile, but may present where it joins the body a definite constriction, or even a pedicle; the base of the sac is covered with healthy skin, and the fundus is covered only by thin epidermis or by the spinal membranes themselves. Pressure upon the tumor is found to diminish

its size and to increase the tension of the anterior fontanelle, and possibly to cause convulsions or stupor. The cyst is translucent, and the margins of the bony aperture are distinct. Crying, coughing, or pressure upon the anterior fontanelle makes the tumor more tense. Spina bifida is apt to be associated with club-foot, with hydrocephalus, and with rectal or vesical paralysis. Spina bifida usually causes death. A few meningoceles and a very few meningo myeloceles undergo spontaneous cure by the shrinking of the sac. Syringo-myelocele is invariably fatal. The cause of death may be rupture of the sac or marasmus.

Treatment. Very small protrusions which grow slowly and are covered with sound skin may be treated by the use of a compress and bandage, by an elastic bandage, or by applications of contractile collodion. Some surgeons tap and drain the sac. Injection is used by many. The sac being cleaned, the child is placed on its side and a little chloroform is given. A fine trocar is plunged obliquely in at the side through sound skin, little or no fluid being drawn off, and 3j of Morton's fluid is injected (iodine, gr. x; iodide of potassium, gr. xxx; glycerin, 3j). The trocar is withdrawn and the puncture is sealed with a bit of gauze and iodoform collodion. The child is put to bed. If the injection proves successful, the sac shrinks; if the injection. fails, it may be repeated at intervals of from seven to ten days (Jacobson, White). Many surgeons prefer excision of the sac. Bayer treats it as he would a hernia.

Tumors of the Spine.-Among congenital tumors are lipomata and cysts (dermoid, congenital, sacral, and fœtal). Tubercle, gumma, psammoma, and fibroma may arise from. the cord or its membranes. Glioma is the most usual growth. Primary sarcoma is rare. Angeioma may occur. Carcinoma is never primary. A tumor rarely produces obvious symptoms until it is as large as a hazel-nut.