Atlanto Axial dislocation with cervical myelopathy with Ankylosing spondylitis.
Case: A 27 years female, a known case of ankylosing spondylitis with stiff(Ankylosed) neck since 6 years, presented with severe neck pain and deformity since 2 months. The pain and deformity was sudden in onset without associated history of any significant trauma or any episode of cough and cold. She was able to move her neck from the fixed position. No history of bladder bowel disturbance.
On Examination: There was fixed flexion rotation deformity of neck

(Figure 1).

Neurology:
Higher functions and cranial nerves were normal.
Power in bilateral upper and lower limbs was grade 5 except in bilateral C7 and T1 which was grade 4.All deep tendon reflexes were exaggerated. Ankle clonus was present bilaterally. Planters were extensors bilaterally. Scapulohumeral reflex present.
Roentgenographic Examination revealed atlanto axial dislocation with ankylosed subaxial spine

(Figure 2).

Computed Tomograph(Figure 3) and MRI(Figure 4) revealed atlantoaxial dislocation with compression and signal intensity changes at cervicomedullary junction.

Figure 3

PATIENT PROBLEMS:

1. C1-C2 dislocation
2. Severe pain
3. Compressive Myelopathy
4. Ankylosing Spondylitis

The patient was put on skull traction using gardenwell tongs. This corrected the rotational deformity of the head. The repeat CT showed partial reduction of the atlantaaxial joint and increase in the space available for the cord at C1 level(Figure 5). It also revealed the arthritic atlantoaxial joint and the fused zygoapophyseal joint.

Figure5

The pedicle of C2, C3 were very thin(Figure 6).

Figure 6

  TECHNICAL PROBLEMS:

1. Ankylosed spine
2. Osteoporosis
3. Thin pedicles
4. Artheritic C1-C2 joints

The patient was operated with Navigation guided C1-C2 fusion.
Procedure: Patient was positioned prone. C1, C2, C3 and C4 was exposed. Mirra attached to the C4 Spinous process and registration of the anatomy was done using 3D Iso C arm to get the saggital, coronal and axial images( Figure 7).

Figure 7

C1and C2 screws inserted under Navigation guidance(Figure 8).

Figure 8

Because of the thin pars on the right side and high arched vertebral artery, on this side a translaminar screw was inserted(Figure 9).

Rods attached on both sides and bone graft added.
Postoperatively patient was mobilized with cervical collar by 5th post op day.
Post operative Xray show the good alignment of C1 and C2 with screws in good position(Figure 10).

Figure 10

LEARNING POINTS:

• In ankylosed spine even minor trauma can cause severe injuries.
• Even in long standing cases where the deformity seems to be fixed, traction can help.
• CT scan and particularly the cuts through the pedicles help to know the morphology of the vertebrae and plan treatment.
• If some reason precludes the use of the C2 pars screw, then the translaminar screw can be used.
• Navigation increases the accuracy and safety in these complex cases.