Purpose: Mucopolysaccharidosis IVA (MPS IVA) is a multisystemic storage disorder. Patient's disability and life expectancy depends upon skeletal complications, including cervical myelopathy due to upper cervical compression or instability. Posterior decompression followed by occipitocervical fixation or C1-2 fusion are the most frequently recommended surgical interventions. The bony elements of C1 and C2 are often inadequately developed making routine screw insertion difficult. The main purpose of this work was to present novel technique of occipitocervical fixation using two C2 laminar screws.
Methods: Four children with MPS IVA underwent decompression and C0-C2 instrumented fusion using two C2 bilateral laminar screws. The dimensions of the C2 lamina were measured. Clinical and radiological results were monitored prospectively for a minimum 3 years.
Results: The mean laminar length was 24 ± 1.15 mm, width 6.15 ± 0.55 mm and height 7.4 ± 0.6 mm. Patients remained in a stable neurological condition. The mean antero-posterior diameter of the spinal canal on the pre-operative MR was 6.2 ± 0.74 mm and it was enlarged to 11.4 ± 0.8 mm after 3 years. All screws were placed adequately. In all patients, the control CT scan 2 years post-operatively revealed a stable position of the treated segments, but solid bony fusion was not registered in any patient.
Conclusions: Decompression and fusion of the upper cervical spine is a generally accepted approach to treat upper cervical spine instability and myelopathy in MPS IVA patients. The feasibility and the suitability of the technique of C0-C2 stabilization using bilateral C2 laminar screws have been presented.
Keywords: Laminar; Mucopolysaccharidosis; Screw; Stabilization.