Positional Torticollis

This is related to positional alteration in the craniovertebral junction over a prolonged period of time as well as indentation of the odontoid process into the cervicomedullary cord. Such an indentation is seen in patients with group I basilar invagination. The physical neck alterations simulate the changes in spinal posturing secondary to disk herniation. The torticollis seen in patients with group I basilar invagination is present in most cases. The long-standing torticollis seen in such cases appears to be part of a protective alteration that occurs as an attempt to prevent the spinal cord from relentlessly and progressively reducing the spinal canal. Our recent observations suggest that such a torticollis (and even short neck) is reversible following decompression and stabilization of the craniovertebral junction.4

Treatment

Direct manipulation of the atlantoaxial joint and distraction of facets with bone graft, with or without titanium metal spacers, have been shown to result in reduction of basilar invagination and fixed atlantoaxial dislocation ( Figs. 31.1 and 31.2 ). We have observed remarkable reduction of torticollis by this method of treatment ( Fig. 31.2 ). Differential distraction of the facets can also result in direct reduction of torticollis ( Fig. 31.1 ). Torticollis reduces even after transoral decompression of the odontoid process.

Spasmodic Torticollis

The torticollis in this group is related to sternocleidomastoid muscle spasm ( Fig. 31.3 ). The pathology in these cases and the treatment remain controversial. Botulinum toxin injections in the spasmodic muscles have been found to be a satisfactory treatment modality in resistant cases.

Facetal Rotatory Torticollis

Torticollis in this group is related to rotatory atlanto-axial dislocation secondary to rotatory dislocation of the facet of the atlas over the facet of the axis ( Figs. 31.4 and Fig. 31.5 ). This group forms a discrete entity and is the subject of discussion in this chapter. Locking of the atlantoaxial facets results in rotatory atlantoaxial dislocation. Such a dislocation has been identified more commonly in young children. Although several pathogenetic factors have been considered, the exact cause of the phenomenon is unclear. The dislocation is an acute event that usually follows an episode of relatively minor trauma. Some patients had throat and paranasal sinus infections or tonsillitis at the time of the event. However, an exact correlation between possible infection, trauma, and atlantoaxial dislocation is only speculative.

Historical Background and Nomenclature

Rotatory dislocation of the atlantoaxial joint was first described by Sir Charles Bell in 18305 and Corner in 1907.6 Wortzman and Dewar introduced the term atlantoaxial rotatory fixation-subluxation in 1968.7

Rotatory atlantoaxial dislocation can be subdivided into reducible or irreducible types. Reducible rotatory atlantoaxial dislocation is classified as one in which the dislocation reduces on dynamic images or after institution of cervical traction. It is usually incomplete, when some part of the facet of the atlas is in contact with the facet of the axis. Complete rotatory dislocation can also reduce on traction, but the possibilities of its reduction are relatively less. Mobile and reducible rotatory dislocation can be treated by conservative observation for ∼3 months using halo traction or a cervical collar. If during that period the rotatory dislocation reduces and remains reduced on dynamic imaging, there is no need for surgery. Otherwise, surgical fixation of the rotatory dislocation in a reduced position should be performed. In cases with irreducible rotatory dislocation, an attempt can be made to reduce the dislocation by local distraction and reduction by manual realignment.

The main presenting symptom of rotatory atlanto-axial dislocation is torticollis of the neck; neurological symptoms may be marginal. The torticollis may be painless. Surgical treatment for rotatory dislocation is to fix the dislocation in the reduced or maximally reduced position. Some surgeons feel that segmental fixation of the dislocation, even if it is in a dislocated position, allows the subaxial spine to move better, and torticollis can be expected to recover.

Biomechanics

The occipitoatlantoaxial joints are the most complex joints of the axial skeleton. This joint complex forms part of the primary pillar of the spine that provides stability and mobility to the head. The primary movement of the atlanto-occipital articulation is flexion-extension; of the atlantoaxial joints, rotation ( Table 31.1 ). The geometry of the lateral atlantoaxial articular surfaces is such that they are convex with horizontal orientation, thus able to permit rotation. The maximum rotation between the atlas and the axis is ∼45°.8 When rotation exceeds 45°, the inferior facet of the atlas interlocks over the superior facet of the axis. If the transverse ligament is deficient, this facet interlock may occur even with rotation < 45°. It has also been seen that if the transverse ligament remains intact, the anterior arch of the atlas will not subluxate over the axis unless there is > 65° of rotation.

The alar ligaments limit axial rotation and side bending of the C0–C1–C2 complex. The left alar ligament limits rotation of C1 and the head to the right, and the right alar ligament limits rotation to the left. The vertebral arteries located in the foramen transversarium are not affected by the extremes of normal rotation, but they can be severely compromised by excessive rotation, especially if combined with anterior displacement.9 The fact that the vertebral artery has a dynamic relationship with the bones during rotational movements was first discussed by us.10 The laxity of the vertebral artery in the region assists in facilitating a range of neck movements.