—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]
[47] Stewart, Some Affections of the Cervical Sympathetic, The Practitioner, February, 1905.
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].)
Fig. 407
Diagram to illustrate the relations of the cervical sympathetic and the mechanism of the various disturbances following lesions of its trunk. (Stewart.)
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]).