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Operative Paralysis of the Spinal Accessory Nerve

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OPERATIVE PARALYSIS OF THE SPINAL ACCESSORY NERVE.

The chief clinical importance of paralysis of the spinal accessory nerve is surgical. The nerve has a long course in the neck and traverses a region often invaded by tumors, espe cially by those originating in the lymph nodes. Whether they be suppurative, tuberculous, or cancerous, such tumors are usually diffused and tightly bound down to surrounding struc tures. At the time of their removal there is more or less chance of the nerve being cut, either by accident or intentionally for the purpose of thorough extirpation. Within the past year two instances have come to my notice of accidental section of the nerve. In both, serious disturbances of motion in the trapezius and sternomastoid immediately followed the opera tion. Such a result contradicts the more common experience. for in most cases the paralysis which results from section of the nerve is not particularly disabling. Large pieces of the nerve are resected for spasmodic wry-neck without fear of serious loss of motor power ; and in only a few of the re ports of accidental section is any mention made of para lytic results of consequence. This is explained by the fact that the cervical nerves commonly participate in the sup ply of the trapezius, so that this muscle is usually paralyzed in part only, and then in a way to not seriously interfere with movements of the shoulder and arm. Also, when the sterno mastoid is totally paralyzed, freedom of movement of the head and neck is impaired, but it is not abolished. Even when both muscles are entirely put out of service, the erect position of the head is not seriously interfered with. In the two cases referred to as seen by me the paralysis which resulted from accidental section of the spinal accessory was much more dis abling than usually met with as a result of such an accident. With the view of determining the reason of the varying re sults from a common cause, I was tempted to turn again to the well-worn subject of the nerve supply of these two mus cles.

The old terminology and conception as to the function of the accessorius have recently been called into question. On experimental evidence, it is now regarded as a spinal nerve pure and simple, and the cells of origin in the medulla, pri marily ascribed to it, are believed to belong to the vagus. There is little reason to doubt that this allocation is correct. The purposes of the present paper can best be served, however, by retaining the old nomenclature, as is done in most anato mies. The spinal portion of the nerve which is destined for the sternomastoid and trapezius, and which is represented by the external branch, springs from the upper five cervical seg ments of the cord. The accessory portion, soon after its exit from the jugular foramen, sends its fibres, through the internal branch, to the vagus, to join in the nerve supply of the pharynx and larynx. Paralysis of the nerve, consequently, presents a varying symptomatology, according to the site of the lesion. If the spinal portion alone is affected, the trapezius and the sternomastoid show a loss of power, without symptoms refer able to the larynx and pharynx. Among the producers of such a condition are, outside the cord, fracture of the cervical ver tebrm, cervical caries, syphilitic pachymeningitis, and such diseases as syringomyelia, locomotor ataxia, progressive mus cular atrophy, and traumatic hmmatomyelia.

Within the skull, after the spinal and accessory portions have united, symptoms due to affections of both portions may result from basal lesions generally. The division of the nerve into an external and internal branch, of which the former goes to the sternomastoid and trapezius, and the latter through the vagus to the larynx and the pharynx, occurs immediately after exit from the cranial cavity; therefore, an injury outside the skull, to cause symptoms referable to both branches, must be situated directly at the skull base. The present paper con cerns itself almost entirely with extracranial affection of the nerve. With the rare exception of penetrating wounds at the base of the skull, extracranial lesions of the spinal accessory are always confined to the external branch, and are nearly always traumatic. I have found no reconl of the nerve having been compressed by new growths in a i. ty to cause paralytic symptoms. Neuritis in this nerve is rare.

In the following two cases the paralysis was the direct result of surgical operation.

I. The patient, a young girl, was seen at the New York Orthopmdic Hospital in November. There was a scar ex tending downward, two or three inches from the mastoid process, along the anterior border of the sternomastoid muscle. The patient said this was the result of an operation undergone a few weeks previously for enlarged glands. The right sternomastoid and trapezius muscles were paralyzed, and there was slight arms thesia of the back of the ear. Much to my regret, tne examina tion of this patient was cursory, as I intended to make a more thorough one before the operation of neurorrhaphy, which I ad vised. The patient did not return to the hospital, however, and we have been unable to find her. From memory, however, I can say that she had complete paralysis, with atrophy, and degenerative electrical reactions in the sternomastoid and upper part of the trapezius. The right arm hung down, the head could not be turned to the left, and there was great loss of power in elevating the shoulder. The middle portion of the trapezius was not ex amined. I cannot say whether it was paralyzed or not.

II. The second case is one of more than ordinary interest. The patient, a robust workman, was operated upon in March, 19oo, for a deep suppurating gland of the right side of the neck. The incision was along the anterior border of the sternomastoid process, not over one and one-half inches in length. Soon after the operation, impairment of motion about the right shoulder was observed, and on April 9 I made an examination at the Vanderbilt Clinic. The patient presented a classical picture of unilateral paralysis of the sternomastoid and trapezius mus cles. The head was inclined slightly forward, the shoulder was depressed, the arm hung heavily with slight forward rotation, the scapula was drawn away from the spine and rotated on its horizontal axis, and there was a slight scoliosis, with convexity towards the left. The part of the neck and shoulder normally formed by the trapezius was greatly lessened in volume. This caused a sinking of the line extending from the occiput to the acromion process, and a loss in the fulness of the base of the neck on the affected side. (Fig. I.) Voluntary movement and elec trical reactions were normal in all muscles except the right sternomastoid and trapezius. These two muscles were totally paralyzed and presented degenerative electrical reactions. The patient was unable to turn the head to the left and had difficulty in bending the head forward. The affection of the trapezius was shown by great disability in raising the shoulder and in adducting the shoulder-blade. The arm could not be elevated much above an angle of ninety degrees. The resulting incapacity was ex treme. The patient was practically deprived of the use of his right arm for all heavy work. I wish to particularly emphasize this in showing how serious a calamity to any one, but especially to a laboring man, complete paralysis of the trapezius is. Form ing, as it does, the most important support of the shoulder, the loss of the trapezius practically does away with the power of lifting weights which are at all heavy. The deltoid, in losing its support, loses much of its usefulness, and lifting must be done by the flexion of the forearm and by a bending of the whole body. The patient in the present case has been, ever since the onset of his palsy, completely incapacitated for his work. As far as sen sory symptoms are concerned, there was no pain. But the patient complained of a feeling of numbness about and behind the left ear. Examination showed that there was a diminution in tactile sensibility in this region. There was no doubt as to the diagnosis. The right spinal accessory nerve had been accidentally cut during the operation, and with it the great auricular nerve.

Neurorrhaphy was performed about six weeks after the origi nal operation. The cut ends of the nerve were found to be considerably separated, an inch or more. Within a few weeks from the suturing, the electrical reaction improved. At present (December, 19oo) there is still a great diminution in faradic excitability, but there is no longer any reversal in the reactions to the galvanic current. The improvement in motor power has been slow. This patient suffered a peculiar complication in the shape of partial palsy of the circumflex and musculospiral nerves. This came on months after the original operation. It was due to press ure during sleep. The man admitted sleeping on his arm, and as soon as his attention was called to the danger of the proceeding, these palsies began to improve, and are now well on the way to recovery.

The chief interest of this case to me has been the proba bility of its casting some light upon the vexed question of the nerve supply of the sternomastoid and trapezius muscles.

While some authorities state that the spinal accessory supply to both muscles is reinforced by the cervical nerves, the more recent views seem to agree that the sternomastoid, at least, gets its sole innervation from the accessorius, but that the trapezius is supplied by some of the cervical nerves which pierce it. There does not seem to be an agreement of opinion as to which these cervical nerves are, nor as to which of the three parts of the muscles they are distributed. For example, Oppenheim states that the clavicular portion of the trapezius is the one most frequently supplied by means of cervical branches, while Remak believes that it is the middle portion. Indeed, Remak has gone so far as to maintain that total palsy of the trapezius does not occur as a result of section of the spinal accessory, either within the skull or directly after its exit from the jugular foramen. He believes that the charac teristic falling away from the spine of the upper internal angle of the scapula (Schaukelstellung-mouvement de bascule), which results from paralysis of the middle portion of the mus cle, is invariably dependent upon lesion of the cervical nerves; and that when the spinal accessory is the only nerve affected, this portion of the trapezius is spared. In support of this opin ion he adduces a case in which, after section of the nerve soon after its exit from the skull, the middle portion of the trapezius was not paralyzed.

It is, however, rather dangerous to make too absolute claims in regard to nerves whose function is still uncertain, and especially in regard to nerves which enter into plexus formation.

Remak's position is rendered untenable by the second case of my series. Also Freund quotes a case reported by Mann, in which bilateral and total palsy of both trapezius and sterno mastoid resulted from operation for bilateral cervical glands. The details of this case as to the site of the operation, etc., are not given, but Mann says, "in view of the situation of the lesion, a lesion of the accessorius is the only one which can be held responsible for the condition." Still more convincing is a case of Traumann's, in which the nerve was divided by a stab wound so close to the base of the skull that the internal branch of the accessorius was also cut—i.e., well out of the region of the cervical nerves. There resulted palsy of the sternomastoid and of all portions of the trapezius. The com plete palsy of the trapezius proved that it had received its whole supply from the spinal accessory.

These conflicting reports can only be harmonized by as suming that occasionally there is a variation from the custom ary route by which the motor impulses pass from the spinal cord to the trapezius. Such an assumption receives some sup port from the fact that the trapezius is not, in its anatomical relations, a fixed muscle. In man it may be congenitally ab sent in whole or in part ; in the lower apes it is supplemented by another similar muscle called the spinocervicalis.

It has been shown by embryological researches that the relationship between the neural segments and their correspond ing muscle segments is constant and not subject to change ; that whatever other variations occur there are none between individual neurotomes and the myotomes they are destined to supply. But anatomy abundantly teaches that the route by which these segmental elements are associated is more or less elective and subject to variation. In the case of the trapezius, I take the variation to be as follows (Fig. 2) : The spinal centre situated between the first and fifth cervi cal segments of the cord is fixed and constant. As a general rule, the cells of this centre send their axones to the trapezius through both the spinal accessory and the cervical nerves. But sometimes there is a variation from this arrangement in that all the axones pass to the muscle in the spinal accessory, leaving the cervical nerves without function, as far as the trapezius is concerned. Under these circumstances, the motor impulses reach the trapezius exclusively through the spinal accessory, and section of it consequently means total palsy.

trapezius, cervical, sternomastoid, patient, nerves, operation and portion