62. Congenital torticollis (sternomastoid tumour)
This chapter was written with help from Rujuta Mehta and Mandar Agashe both paediatric orthopaedic surgeons from Mumbai India. Mandar was Rujuta’s understudy at one time. The anatomical dissections were performed by Chirag Bhansali a post graduate student in plastic surgery at the Lokmanya Tilak hospital in Mumbai.
1. The sternomastoid muscle arises by way of a sternal as well as a clavicular head and the latter is flatter broader and somewhat aponeurotic while the sternal head is shaped like a belly The two origins enclose a hollow space which is considered an aesthetic surface landmark. The clavicular head ascends directly to the mastoid bone to which it is attached but on its way, in its middle third, passes behind the sternal head and this arrangement together with it’s dual separate origins, enclosing a fossa, marks it as a spiral cruciate muscle. The muscle lies deep to the platysma in its entirety. This fascio-muscular structure is incised first in order to expose the muscle. The sternal head ascends beyond its main insertion into the mastoid bone onwards onto the nuchal line on the occipital bone of the skull. The mastoid attachment of the muscle lies adjacent to inferior pole of the parotid gland (see figures below paragraph 2). The contraction of this muscle tilts the head to the ipsilateral side and also rotates it to the opposite side resulting in a contralateral upward glance. The most frequently noticed motion brought on by these muscles acting together is the ‘level rotation’ from side to side.
2. In its lower third the muscle is crossed by the omohyoid muscle on its deeper surface and inferior to this the anterior jugular vein crosses its deep surface which in this area is joined by the clavicular vein but these veins lie superficial to the sterno-hyoid muscle. The external jugular vein crosses the muscle in it’s upper third superficial to it. From here up-to the posterior belly of the digastric the carotid vessels in their sheath lie immediately deep to the sternomastoid . Also at the level of the posterior belly of the diagastric, the spinal accessory nerve enters the muscle from its deep surface, supplies it and exits the muscle in its middle from its posterior border. In cases of a congenital shortening of the muscle, these important anatomical landmarks might be somewhat telescoped on each other but must be remembered to avoid injury to them. For example an injury to the anterior jugular vein can be quite troublesome. When the muscle is released at its insertion from the mastoid bone it is best to release the muscle sub-periosteally to avoid injury to the lower pole of the parotid gland or the accessory nerve which enters the muscle a little lower down. An unnamed vein crosses the insertion on its superficial surface which too may cause troublesome oozing unless the release is performed sub periosteally.
Photoshopped from Gray’s Anatomy
3. The condition is almost always unilateral and though a bilateral deformity has been mentioned that condition is probably a generalised shortening of multiple structures in the neck as well as fusion of cervical vertebrae as occurs in such conditions as the Klippel-Feil syndrome. The incidence of the unilateral condition is about. 3 for every thousand births out of which a small fraction might have other skeletal abnormalities, a dysplasia of the hip being the commonest. A mal-positioning of the head in the uterus particularly in a breech presentation or a vascular insufficiency (intra utero) have been thought to be the commonest causes for this deformity. An unexplained compartment syndrome has also been blamed for its occurrence. That a hematoma leads to this deformity is not accepted anymore because biopsies have never revealed any traces of hemosiderin. The deformity has also been attributed to birth canal injuries during parturition followed by scarring and here the deformity is strictly not congenital in nature. When the deformity is present at birth it has often been called a sterno-mastoid tumour because it presents like a swelling and in many cases with or without physical therapy the swelling seems to subside leaving behind a tight band of varying breadth in the neck.
4. The effects of the shortening of the muscle leading to torticollis vary depending on the severity of the shortage. A transient mild condition has been described. Some passive exercises is all that is required in such cases. Here on successively, more severe conditions are visible and can be graded according to an angle between a horizontal line drawn on upper surface of the last cervical vertebra and a line drawn between the two angles of the mandible. This test is rarely done to estimate the severity of the condition but is sometimes used to gauge the correction obtained by surgery. An angle less than five degrees is considered a satisfactory post-operative result and the residual deformity is assumed to be correctable by subsequent physiotherapy which may be helped on further by either a static or a dynamic one where a screw is employed, on an appliance. While the effects of the deformity on the cervical spine are often visible on an x-ray the effects almost never result in any neurological consequences and in today’s day and age when most deformities get treated prior to puberty, even in the developing countries, it has been observed that the spinal deformation returns to normal.
5. A condition called acute torticollis also occurs following a poorly positioned neck during near comatose sleep usually following drug abuse or after an alcoholic binge. A more frequent occurrence is on account of an inflammatory condition in the vicinity of the muscle or an irritation of a nerve root emerging from the cervical spinal cord frequently due to a prolapsed inter vertebral disc .In both cases the primary condition must be diagnosed and treated
6. In a majority of cases congenital torticollis is diagnosed by the abnormal position of the neck in early infancy or at birth. Occasionally the condition is diagnosed as a refractory error, noticed in the school which in fact is caused by the abnormal position of the neck. As mentioned above milder versions can be treated by physical therapy alone. In the more severe forms surgery will be needed bearing in mind the secondary changes that might have resulted in the adjoining or deeper tissues following the long standing contracture of the muscle. This mainly includes the deep fascia here in this case the platysma and might rarely involve the carotid sheath which is formed by the deep investing fascia as well as the scalenus anterior muscle or its overlapping fascia (please see figure in para two). Though common wisdom suggests that such secondary contractures are usually amenable to post-operative physical therapy and dynamic splints the difficulties of executing this programme in children must be borne in mind during surgery. There is absolute unanimity however about the need for the release of the deep fascia (the platysma in this instance) in all cases and this usually suffices to correct the deformity but if not, an intra-operative palpation, followed by a judgement on the part of the surgeon has to be relied upon to take a decision, as to whether a surgical release of the scelenus anterior muscle and the carotid sheath is needed. When the deformity is treated by a bipolar approach (please see paragraph 9) in which both the origin and insertion are released some undermining of skin followed by a partial fasciectomy has been advocated for very severe contractures. The literature also mentions a Z plasty on the tendon of the muscle at its origin but this perhaps is rarely practised today.
7. In many cases a moderate to severe deformity is accompanied by deformation of the face in which the orbital fissure is inclined downwards towards the affected side mainly because of malar hypoplasia and there is a tendency for the skull to be plagiocephalic (flat)in the frontal and occipital regions. Surprisingly these changes may be present at birth. Surprisingly because the growth of the membranous bone around the skull and the face occurs by genetically induced addition of bone as well as by muscular traction during early infancy and childhood. The fact that such changes occur early may mean that there is a syndromic element involved particularly because the area of the face and the neck develop from adjoining arches. On the other hand the absence of a full range of motion in the neck is bound to affect movements of the face in general which too can lead to the bony hypoplasia. Positional flattening (in the supine position) of the occipital as well as the parietal bone is well known and it is likely that in congenital torticollis such flattening is more common due to the contracture of the neck which makes it difficult for the child to sleep on the side opposite to the side of the deformity. What is remarkable is the desultory attention that has been paid to this subject in the available literature though evidence has been cited to show that the successful treatment of the condition in early childhood arrests the further development of deformation. Also there is very little material available as to if these craniofacial deformities are surgically treated to improve the appearance of the face or the skull in cases where the condition is treated in older children.
8. The general consensus appears to be inclined to operate on these children at around the age of four years before the child starts formal schooling after some form of physical therapy has been given till then. In the infant, this involves passive stretching and it has been claimed that a large number of children respond to this treatment enough to not require any surgical treatment at all. Also surgery in early infancy is comparatively difficult on account of the reduced span of the neck and the tissues may have telescoped on each other. In addition, no significant advantage seems to be gained by early surgery and any form of post operative splintage is difficult to maintain at that age. There are several reports of surgery being undertaken as late as twelve years either because the patient came late or (surprisingly) by choice and equally good results have been claimed.
9. A majority of surgeons opt to release the contracture of the sternomastoid at the lower end at its origin which is the rational thing to do as is done in ischaemic contractures around the elbow (Volkman’s) in which the common flexor origin is released and stripped down beginning with the medial epicondyle or as in an adduction contracture of the thumb in the palm in which the origin of the adductor is stripped of its origin from the metacarpal. Yet there is probably a smaller group of surgeons who continue to employ a bipolar method in which the muscle is stripped from its insertion as well, over the mastoid bone on which it is inserted. Additionally, there is a group which releases the muscle only at its insertion over the mastoid bone. At least some surgeons migrate to the bipolar method due the dissatisfaction of the results of the unipolar method (when the muscle was released at the origin at the lower end). It stands to reason that if the release of the secondarily contracted fascia is to be effective then its release in two areas in a bi-pedicle fashion at the two ends would be more singular because the area of the total contracture is large and vertically disposed. A series comparing the results of the three methods is difficult to collate because exactly similar cases with identical secondary contractures are difficult to assemble.
Contributed by Mandar Agashe.
Contributed by Mandar Agashe