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|LETTER TO EDITOR
|Year : 2015 | Volume
| Issue : 2 | Page : 279-281
Traumatic atlantoaxial rotatory subluxation with remote cervical spinal cord contusion in a child
Prasad Krishnan, Rajaraman Kartikueyan
Department of Neurosurgery, National Neurosciences Centre, Peerless Hospital Campus, 2nd Floor, 360 Panchasayar, Kolkata, West Bengal, India
|Date of Web Publication||5-May-2015|
Department of Neurosurgery, National Neurosciences Centre, Peerless Hospital Campus, 2nd Floor, 360 Panchasayar, Kolkata, West Bengal
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Krishnan P, Kartikueyan R. Traumatic atlantoaxial rotatory subluxation with remote cervical spinal cord contusion in a child. Neurol India 2015;63:279-81
Atlanto-axial rotatory subluxation in children is an uncommon injury that can usually be treated conservatively. It commonly presents with only torticollis and neck pain without neurological deficits. We describe a patient who had, along with this rotatory subluxation, a distant cord contusion (with normal imaging of the subaxial vertebral column) resulting in left upper limb monoplegia.
A 10-year-old right-handed boy was admitted 2 days after a fall from a train following which he had loss of power in his left upper limb and was unable to move his neck. He was complaining of severe neck pain. He was found to have a fixed torticollis with his face turned to the right. The left upper limb was flaccid, areflexic and with grade 0/5 power in all muscle groups. He was able to perceive pain and touch sensation, although this was less compared with the right upper limb. A computed tomography (CT) scan of the cervical spine showed rotatory subluxation of C1 on C2 with no fracture visualized either at the cranio-vertebral junction or in the subaxial spine [Figure 1] and [Figure 2]. Magnetic resonance imaging (MRI) of the cervical spine revealed a C1-C2 rotatory subluxation with a tear of the transverse ligament of the Atlas More Details [Figure 3]. There was a cord contusion on the left side at the C3-C4 level, remote from the site of dislocation, with no evidence of ligamentous or disc disruption at that level [Figure 4]. The patient underwent a C1 and C2 fixation by the posterior cervical approach using the Goel's technique (C1 lateral mass to C2 pedicle) after achieving an intraoperative reduction of the dislocation by using polyaxial lateral mass screws and a rod construct [Figure 5]. He was immobilized on a Philadelphia collar post-operatively and placed on limb physiotherapy. Over the next few weeks, he regained almost normal power in the left upper limb except for residual weakness in the left deltoid and supraspinatus muscles.
|Figure 1: Computed tomography scan of the cervical spine with 3D reconstruction (a, b) showing rotatory subluxation of C1 on C2 with no fracture visualized either at the cranio-vertebral junction or in the subaxial spine|
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|Figure 2: Axial computed tomography scan images showing the rotatory subluxation of C1 on C2|
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|Figure 3: Axial T2 -weighted magnetic resonance images showing a tear in the transverse ligament of the atlas on the right side|
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|Figure 4: Axial, coronal and sagittal T2 - weighted magnetic resonance images showing cord contusion on the left side at the C3 - C4 level|
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|Figure 5: Post - operative computed tomography images showing (a) screws passing through the lateral mass of the atlas in axial sections, (b) screws passing through the lateral mass of the axis in axial sections, (c) lateral scanogram of the spine showing alignment of the vertebrae and the position of the screws, and (d) normal alignment of C1 on C2 as seen on the reconstructed images|
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Multilevel involvement of the spine, as in this case, has been reported to occur in 7-22% patients in various studies focusing on pediatric spinal injuries.  Our case was unique in that there was a demonstrable disruption of the osseo-ligamentous complex without neural injury in the upper cervical spine, while a spinal cord injury without any bony involvement was seen lower down.
A larger head relative to the spine in children shifts upwards "the fulcrum of movement" produced by the force causing trauma  (unlike in adults where the fulcrum is lower down). In pediatric spinal injuries, therefore, a higher incidence of upper cervical involvement is detected;  in our case, a C1-C2 rotatory subluxation occurred.
The condition of spinal cord injury without radiological abnormality (SCIWORA) was first described based on X-ray films by Pang and Wilberger in 1982.  With further advances in imaging, this definition is "antiquated" and, correspondingly, the number of cases that truly fit the criteria describing the entity without "radiological abnormality" has decreased. MRI and CT scans can now delineate ligamentous injuries and small bony injuries as well. However, a small proportion of patients with a true SCIWORA, as in our case at the C3-4 level, still remain.
In children, there is an increased elasticity of the spine due to the poorly developed uncinate processes, weak nuchal muscles, shallow facet joints and lax ligaments and capsules when compared with adults. , However, CT scans and MRI in our case showed no evidence of capsular or facetal disruption, bony wedging, ligamentous tear or muscle contusion. It has been reported in cadaveric studies that, in the pediatric age group, the spine can stretch by up to 2 inches prior to disruption as opposed to the spinal cord, which can only be stretched by 0.25 inches.  We speculate that the inertial force causing sudden rotation of the head to the opposite side may have caused stretching of the cord and a remote shearing, leading to contusion at a distant site in this patient.
While most cases of atlanto-axial rotatory subluxation can be treated by a collar or a traction for 72 h to achieve reduction, which can be followed by external immobilization,  it is recommended that MR findings of ligamentous injury or instability is an indication to proceed with surgery. , As our patient had a fixed dislocation and transverse atlantal ligament tear, and because the injury was severe enough to cause a distant contusion, we deemed it necessary to proceed with surgery for reduction and fixation.
Several options are available for C1-C2 fixation, including C1-C2 sublaminar wire fixation, interlaminar clamps and C1-C2 transarticular screw placement. However, the first two are biomechanically inferior , as they allow a certain degree of rotational mobility and the latter has a greater risk of vertebral artery injury  (particularly if a good reduction is not achieved prior to screw placement). The Goel's technique, , i.e. C1 lateral mass to C2 fixation, is also challenging in children due to the following reasons - a small size of the lateral masses of the atlas and axis and a softer pedicle of C2, due to which medial penetration of the C2 pedicle by the screw is a risk. However, our familiarity with this technique made it the procedure of choice to achieve a C1-2 reduction. A report in the literature  that deals with pediatric atlanto-axial fixation using this technique (in five cases), has reported satisfactory results with this procedure even in children.
To conclude, multiple sites of injury must always be looked for in cases of pediatric spinal trauma as spinal cord injury may not always be associated with demonstrable fractures or dislocations at the same vertebral level. Although most of these cases can be managed conservatively, careful examination of the MRI and identifying disruption of ligaments like the transverse ligament of the atlas should prompt the surgeon to proceed with an operative intervention even if the rotatory C1-C2 subluxation reduces on conservative treatment.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]