The inferior dental, or third division of the fifth nerve, may be reached in several ways: Its terminal portion where it escapes at the mental foramen; its upper portion by an incision two inches along the lower border of the jaw and above the angle, the masseter muscle being separated from the jaw, and the ascending ramus opened with a ³⁄₄-inch trephine at a point 1¹⁄₄ inches above the angle, its upper edge ¹⁄₄ inch below the sigmoid notch. The nerve is here exposed before it enters the canal. The lingual nerve may also be found resting upon the internal pterygoid muscle. A ligature tied around each nerve, for traction purposes, permits easy tracing of their trunks to the foramen ovale, where, after vigorous stretching, they are divided. They should then be traced downward and at least one inch of their trunks removed.

The Gasserian Ganglion.

—When all three branches of the trifiacial nerve are involved in painful tic, or when operation has already been practised upon one or more of them and the tic has recurred, it becomes necessary to attack the Gasserian ganglion itself.[45] This may be approached by either one of two methods. Both are difficult and serious, having a mortality of from 15 to 20 per cent. As Cushing has pointed out, however, its mortality rate is scarcely as great as the death rate by suicide in neuralgic cases of this kind. The attack from below was first carefully worked out by Rose and then by Andrews, and is begun in much the same way as the operation for the removal of Meckel’s ganglion by resection of the zygoma, described above. A flap is laid up, larger and wider, including the zygoma, with the most complete possible exposure of the zygomatic fossa. The coronoid process is drilled in two places, divided between the openings, which are to be used for subsequent suture, and the temporal muscle pushed upward and forward, out of the way, with the upper fragment. The foramen ovale is then identified by following into it the inferior maxillary nerve, the base of the skull being cleaned away in that neighborhood, and a small trephine opening made between it and the foramen rotundum, connecting these two openings by a much larger one. Through this opening the ganglion is exposed and destroyed piecemeal or extracted as completely as possible. The operation is exceedingly difficult, and hemorrhage, especially from the middle meningeal artery at the foramen spinosum, maybe so troublesome as to make it impracticable unless the carotid be tied. I have preferred in doing this operation to make preliminary ligation of the common carotid, which facilitates the balance of the procedure. The exposure by this method, however, is not as satisfactory as by that next to be described.

Hartley and Krause, about the same time and independently, devised a method of attacking the ganglion, after raising an osteoplastic flap from the side of the skull, which affords a better exposure and a more satisfactory method.

Within reason the larger the osteoplastic flap the easier the balance of the operation. Whether it be square or horseshoe in shape, whether it be made by chisel, by Gigli saw, or by surgical engine, matters little. In fact experience has shown that the conservation of the bone is not a matter of serious import, and there is no good reason why there should be any hesitancy to remove the bone should the formation of such an osteal flap present too many difficulties. After the dura is completely exposed it is to be separated from the base of the skull until the foramen spinosum and middle meningeal artery are reached. It is better to do this quickly and with the finger than slowly with instruments. After this separation the brain with its dural covering is lifted by a spatula or retractor, so as to afford a good view of the region of the ganglion. It will be necessary to double ligate the middle meningeal artery unless preference has been given to make a preliminary temporary or permanent ligation of the carotid. Should this artery have been injured in raising the flap it should be secured before going any farther, either by plugging the opening or canal with gauze or with antiseptic wax (Fig. 401).

The upper surface of the ganglion is adherent to the dura, and these adhesions should be separated. The second and third branches should be identified and divided near their exit. The first branch is in too close relation with the cavernous sinus to justify much interference. The ganglion itself is then seized, after complete isolation, with forceps and evulsed, with as much of its longer and shorter roots as possible. Hemorrhage is checked by adrenalin or by pressure with gauze, as may be required. If gauze be used for the purpose it may also be utilized for drainage. The brain is restored to position and the flap sutured in its proper place.

Before doing either of these operations I should prefer to place the patient within the Crile pneumatic suit and then tilt the body to an angle of at least 45 degrees, thus prompting emptying of the cranial and cervical veins by gravity, while at the same time blood pressure is maintained by the pneumatic pressure (see p. 180).

Abbe has endeavored to lessen the shock of the operation by not formally tearing out the ganglion, but by taking out a section of the nerve trunks between it and their foramen of exit, and then interposing a piece of thin, sterile, rubber tissue, inserting it in such a way that it shall effectually prevent regeneration of nerve trunks across the interval, this rubber being intended to remain and become encapsulated. This method of Abbe seems to have made operative attack upon the Gasserian ganglion less formidable and less dangerous. It remains to be seen whether it is permanently as effective as more complete extirpation.

The Lingual Nerve.

—In some cases of cancer of the tongue there is such intense pain that not only has the lingual artery been tied but the lingual nerve been stretched or exsected. It can ordinarily be reached where it lies on the floor of the mouth beneath the mucous membrane, at the fold between it and the tongue, where it can be felt if the tongue be forcibly stretched. Through a small incision a blunt hook may be passed and the nerve thus secured. Close to the first lower molar the nerve lies in the tongue near the surface, where it can also be found.

The Seventh or Facial Nerve.

—This nerve has sometimes to be stretched for spasmodic affections. When the desire is simply to reach its trunk it may be sought through an incision behind the ear, by which the posterior border of the parotid is exposed, the sternocleidal insertion identified, the nerve lying in the interval between these two landmarks. A more easy method of reaching it would probably be by an incision in front of the ear just before its main branch divides as it enters the parotid gland. If necessary this may be followed backward until the main trunk is reached.

Neuro-anastomosis for Facial Palsy.

—In view of the hopelessness of facial paralysis, when resulting from destructive injuries to the nerve trunk, the introduction of anastomotic methods has marked a very distinct advance. Ballance, in 1895, was the first to apply neuro-anastomotic methods to the facial nerve. He attached the facial to the spinal accessory. His own experience, as well as that of half-a-dozen later operators, proved that nerve regeneration is possible, but that in this particular instance voluntary movements of the face were often accompanied by distressing and unsightly associated movements of the shoulder, and vice versa. Hence, Taylor and others suggested the use of the hypoglossal instead of the spinal accessory, the former being a purely motor nerve running near the facial, intimately associated with it in function, and arising by nuclei, which are equally closely associated in the cranial centres. The operation is indicated in all cases of paralysis caused by lesion of the nucleus within the brain, or the nerve trunk at the base of the brain, or along its course. It is justifiable in Bell’s palsy, when there is complete reaction of degeneration in the facial nerve after several months of treatment (Fig. 402).

The steps of the operation are practically as follows: Incision is made along the anterior margin of the mastoid and the sternomastoid muscle, and the parotid gland is retracted forward and the posterior belly of the digastric is exposed. It should then be pulled downward and backward and divided if necessary. The styloid process is identified, and the facial nerve which emerges from the stylomastoid foramen near its base is then sought and isolated. It should be separated as high as possible and divided close to its exit, so that one-half inch of its free trunk may be secured before it enters the gland. Two fine silk sutures are then passed, one on either side, through the peripheral end of its sheath and tied, the ends remaining long, to be subsequently used. This nerve end should be trimmed to a wedge shape. Next the transverse process of the atlas is identified and the deep cervical fascia divided. This will expose the internal jugular, which should be separated and held out of the way. There will now be seen the spinal accessory nerve, which runs obliquely downward and outward, sometimes in front of and sometimes behind the jugular (Fig. 403). When the vein is held forward and the fascia well retracted both the hypoglossal (Fig. 404) and the pneumogastric nerves are seen, with the internal carotid to their inner sides. The former may be identified either by the electric current, which will cause contractions in the muscles supplied by it, or it may be followed down to where it turns forward around the occipital artery and gives off the descendens noni. Here it should be separated until its trunk is sufficiently free, so that the facial stump can be inserted into it without tension. The nerve being elevated by a hook a slit is made in it, about ³⁄₄ inch long. Into this the wedge-shaped end of the facial trunk is introduced, and held there by utilizing the sutures which have already been passed through its sheath. When the nerve is thus firmly held in the cleft, with its end turned toward the direction of nerve supply, a little cargile membrane may be wrapped around the junction and the wound closed.[46]

Nerve regeneration has been known to follow this procedure in a number of cases, and it has given encouraging results. Considerable time, however, is required, and the patients should be warned that results are not to be quickly expected.

The Spinal Accessory Nerve.

—The principal reason for attack upon this nerve is spasmodic torticollis, or wryneck. It is exposed through an incision along the anterior border of the sternocleidomastoid muscle, extending two inches downward from the ear. The nerve is found a little above the level of the hyoid bone; or, again, it may be found by an incision along the outer border of the muscle, opposite its centre, just above which it will be detected (Fig. 405).

The Deep Posterior Cervical Plexus.

—When operation upon the spinal accessory has failed to relieve long-standing and serious spasmodic torticollis, Keen has suggested to divide the first, second, and third cervical nerves. The operation is difficult and not always successful; still it is worth trying. A transverse incision is made below the level of the lobe of the ear, the trapezius being divided and dissected up until the great occipital nerve is found. It is followed after the necessary division of the complexus until its origin from the posterior division is reached. The suboccipital or first cervical nerve, which lies in the triangle close to the occiput that is formed by the two oblique muscles and the posterior rectus, is excised. The exterior branch of the posterior division is found lower down, and should be divided close to the bifurcation of the main nerve (Fig. 406).

The Cervical Sympathetic.

—The cervical sympathetic is a most complicated nerve trunk, furnishing fibers of various functions to the skin, and to the deeper parts fibers which are vasomotor, vaso-inhibitory, pilomotor, and secretory in function. It supplies the various glands, the upper viscera, the heart and bloodvessels, and connects with nerves below, which supply even the genital organs and the non-striped muscles of the body. The upper part has a very important oculopupillary function, as it supplies the dilator pupillæ, the non-striped part of the elevator of the upper lid, and the orbital muscle of Müller, i. e., a small bundle of non-striped muscle which lies behind the globe and projects across the sphenomaxillary fissure at the back of the orbit. (By contraction of this muscle the eye may be pushed forward.) It also supplies the submaxillary gland, the cutaneous bloodvessels, and the sweat glands of the head and neck. The pupil dilating fibers arise in the medulla, run backward in the lateral columns of the cord to the ciliospinal centre, emerge through the anterior roots of the first and second dorsal segments, and enter the inferior cervical ganglion, thence passing upward through the sympathetic trunk to the orbit. Therefore ocular and other symptoms are produced not only by lesions of the external trunk, but also by lesions within the cord at the level of the upper dorsal segments. These nerves may be injured anywhere in the neck, or compressed by inflammatory deposits or new-growths, or even by cicatricial tissue at the apex of a tuberculous lung. Many cases of phthisis show inequality of the pupils. One nerve may be injured in operations on the neck, the result being slight drooping of the lid and flushing of the face, as well as excessive perspiration on the injured side; the corresponding pupil being smaller than the other because of paralysis of the dilators, but contracting to light, as the third cranial nerve which supplies its sphincter is unaffected. The eye will then sink back somewhat, owing to paralysis of Müller’s muscle, and thus permit a nearer closure of the lids. These oculopupillary symptoms are pathognomonic of paralysis of the cervical sympathetic. Cocaine will not dilate a pupil whose dilator has thus been paralyzed. The area of skin supplied with sweat fibers by the cervical sympathetic includes the corresponding side of the head, neck, shoulder, and upper part of the trunk (Fig. 407).

When the cervical sympathetic is unduly stimulated we have dilatation of the pupil, exophthalmos, widening of the palpebral aperture, delayed descent of the upper lid when the patient looks downward, all of which can be imitated or produced by dropping into the eye a solution of cocaine, which stimulates the nerve.[47]

The surgical sympathetic is attacked surgically for three widely variant conditions: epilepsy, glaucoma, and exophthalmic goitre—the first, because of its vasomotor control of the vascular supply of the brain; the second, because of the relation of the nerve to the orbital circulation and nutrition; and third, because of its relations to the thyroid and the heart. In the latter case it is especially desirable to remove the lower cervical ganglion and the first dorsal, if it can be reached, although the procedure here is exceedingly difficult.

The tachycardia of Graves’ disease is due apparently to irritation of the accelerator nerves of the heart, which come from the sympathetic, or else to paralysis of the regulator (pneumogastric) supply. The former spring from the lower part of the cervical cord and the upper dorsal segments, and pass to the third cervical ganglia and to the first dorsal, terminating in the cardiac plexus.

The operation described below is practically that advised by Jonnesco, more or less modified by other operators, and may be varied to some extent to meet the exigencies of particular cases. Thus whether it shall be done through one or two incisions will depend on the will of the operator. It is made about as follows: A long incision is made along the posterior border of the sternomastoid. The latter may be either retracted forward or its fibers separated, in order that the fascia on its inner side may be reached and separated from the deeper muscles. This fascia should be divided as high as the base of the skull. The upper ganglion of the cervical sympathetic lies on the inner side of the anterior tubercle of the transverse process of the second and third vertebral processes, resting upon the muscles covered by this fascia. The ganglion, being recognized by its shape, and the sympathetic trunk being thus identified, the nerve should be divided and made free, as high as possible and just beneath the base of the skull. (See Fig. 408.)

The lower end is to be exposed by continuation of the first incision, or by another beginning 1 Cm. above the clavicle and extending along the posterior border of the sternomastoid for 4 or 5 Cm. The platysma should be entered and the tissues separated upward until the fingers can meet in a channel thus made by connection with the upper incision. The tissues should also be loosened downward until a point has been reached behind the clavicle. They then should be widely retracted and the inferior thyroid artery sought. The middle cervical ganglion is found inside of its curve. Occasionally this ganglion is replaced by a plexus, or the main trunk may pass behind the artery. At this level it is to be seized and its upper divided end pulled down and out through this opening. The nerve trunk should then be followed downward. The artery should be freed from any plexus of sympathetic fibers around it, all of which should be destroyed, and especially those fibers which constitute the middle cardiac nerve, which pass to the inner side. The main trunk is to be drawn down beneath the artery and then followed downward and outward to the lower ganglion, where it lies behind the clavicle, on the neck of the first rib, between the scalenus anticus and the longus colli. The ganglion and the trunk should be separated from the efferent and afferent branches which connect with it, as well as from the vertebral artery; being thus made free it is again drawn outward. Here one should divide especially the cardiac branches which form the lower cardiac nerve, as well as the vertebral branches which have so much to do with controlling the supply through the vertebral artery. The ganglion, after being identified, should be finally removed. The nerve should be traced still farther down to the first thoracic ganglion, which has much to do with supplying the heart, and this also should be separated and destroyed (Fig. 409).

It is rarely necessary to provide for drainage after the operation, unless the retraction and laceration of tissues have been very great. My own preference is to make one long incision along the posterior border of the sternomastoid, by which the dissection is facilitated and the operation made less complicated and difficult. When done for glaucoma on one side it will be sufficient to attack one nerve, but when for epilepsy or for exophthalmic goitre the operation should be bilateral. When for epilepsy or glaucoma it is not so necessary to remove the lower cervical ganglion; this is indicated rather in those cases where it is desirable to control the accelerator nerves to the heart. The operation has given good results in all three affections named, yet it is one of considerable difficulty. It would be made extremely difficult by the presence of a large goitre, and in such case it would probably be better to extirpate the thyroid rather than to attack the nerve. (See Glaucoma, Epilepsy, and Exophthalmic Goitre.)