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Traumatic atlantoaxial rotatory subluxation
  1. T B Crook1,
  2. C A Eynon2
  1. 1Department of Neurosurgery, Wessex Neurological Centre, Southampton, UK
  2. 2Neurosciences Intensive Care Unit, Wessex Neurological Centre, Southampton, UK
  1. Correspondence to:
 Dr C A Eynon
 Director of Neurosciences Intensive Care, Wessex Neurological Centre, Tremona Road, Southampton SO16 6YD, UK; Andy.Eynonsuht.swest.nhs.uk

Abstract

Atlantoaxial rotatory subluxation should be considered in the presentation of traumatic torticollis. This case report discusses the characteristic radiographic findings and appropriate management.

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Torticollis is a relatively frequent presenting sign to an emergency department. It describes lateral flexion of the neck and contralateral rotation, with a variable degree of flexion. The causes may be divided into traumatic and non-traumatic. The differential diagnosis of non-traumatic torticollis should include, particularly in children, congenital cervical spine anomalies, head and neck infection (for example, otitis media, pharyngitis, or retropharyngeal abscess), and tumours in the posterior fossa or upper cervical spine.1 Other causes include drug-induced torticollis—for example, with phenothiazines—and the movement disorder spasmodic torticollis. Traumatic causes of torticollis include atlantoaxial rotatory subluxation, atlantoaxial dislocation, cervical vertebral fractures, and injury to the cervical musculature.

This article highlights a case of atlantoaxial rotatory subluxation with the aim of improving awareness of this condition to enable early recognition. Appropriate management options and outcomes are discussed.

CASE HISTORY

A 15 year old girl tackled an opponent while playing rugby. During the tackle her head was forcibly extended and rotated to the right. She attended her local emergency department complaining of neck pain with her neck in fixed rotation to the right. She had no neurological sequelae. Plain x rays showed abnormality at the atlantoaxial joint (fig 1). A computed tomography (CT) scan confirmed a 45° rotatory subluxation of C1 on C2, with forward subluxation of the lateral mass of the atlas off the axis on the left and posterior subluxation on the right (fig. 2). The atlantodental interval was not increased and no fracture was identified. The patient was transferred to the regional neurosurgical centre. Management consisted of analgesia, sedation, and application of halo skull traction. This allowed clinical reduction of the subluxation within one hour of application. Reduction was confirmed by CT scan. The patient remained in traction for six days before being mobilised in a rigid neck collar. She was discharged without further problems after 11 days. The rigid collar was removed after eight weeks. Outpatient review at three months revealed a full range of painless neck movement.

Figure 1

 Plain anteroposterior x ray of cervical spine demonstrating torticollis with chin directed to the right.

Figure 2

 Computed tomography scan of cervical spine showing approximately 45° rotation of the skull and C1 to the right in relation to C2. Approximately three quarters of the C2 facet is exposed.

DISCUSSION

The atlantoaxial joint primarily facilitates rotation and is stabilised in the anteroposterior plane by the transverse ligament and joint capsule. The alar ligaments, which pass from the lateral occipital processes to the posterolateral margin of the odontoid apex, prevent anterior shift of the atlas on the axis but mainly function in preventing excessive rotation at the atlantoaxial joint. There is evidence from magnetic resonance imaging to suggest that alar ligament disruption is the mechanism by which rotatory subluxation occurs.2,3 The lateral mass of the atlas rotating posteriorly locks behind the ipsilateral lateral mass. Conditions with associated ligamentous laxity or congenital atlantoaxial abnormalities therefore carry an increased incidence of rotatory subluxation. These include Down’s syndrome, Morquio’s syndrome, Marfan’s syndrome, and rheumatoid arthritis. Grisel’s syndrome describes non-traumatic subluxation of the atlantoaxial joint from inflammatory ligamentous laxity following an infectious process.4

Traumatic atlantoaxial rotatory subluxation is predominantly a paediatric phenomenon, with rare occurrence in adults.5,6 It should be included in the differential diagnosis of patients presenting with torticollis following even minor trauma. Two classification systems for rotatory subluxation have been described: the Fielding and Hawkins system,7 and that of White and Panjabi.8 These are based on radiological findings, describing the direction of atlantal displacement and the pivotal axis.

Radiographic features of rotatory subluxation are of persistent asymmetry of the odontoid peg in relation to the lateral masses of the atlas, uncorrected by head rotation. Plain x rays of the cervical spine will detect approximately 93% of rotatory subluxations compared with a detection rate of 54% with CT. When combined, a sensitivity of 99% has been described.9 Complex motion tomographic studies or dynamic CT have also been recommended for the diagnosis of rotatory subluxation.6,9

Acute traumatic atlantoaxial rotatory subluxation is often reduced easily.2,6,10 The length of time between injury and reduction appears to correlate with rates of recurrence and failure of reduction by non-surgical techniques.10 Evidence supports the use of early cranial traction in conjunction with benzodiazepines.6,10 This is followed by external immobilisation (Philadelphia collar or Guilford orthosis) for six weeks. The patients achieve good long term stability.6,10 In cases of recurrence, further cranial traction followed by external immobilisation (once reduced) for three months is advocated.10 For recurrent or irreducible subluxation, open reduction and posterior atlantoaxial fusion may be required.6,7,10

REFERENCES

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Footnotes

  • Competing interests: none declared

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