No abstract

In 17 patients (eleven males, six females) with Morquio-Brailsford syndrome (mucopolysaccharidosis IV) we have used onlay femoral and tibial autografts placed posteriorly and secured to the laminae of C1 and C2 to obtain satisfactory occipito-C1/C2 posterior fusion. They were immobilised postoperatively in a halo-plaster body jacket for four months. The age at operation varied between three and 28 years. Those with myelopathic symptoms of recent onset made some recovery, but severely myelopathic patients showed little or no recovery.We advise prophylactic occipitocervical fusion in these patients since the cartilaginous dens is not strong enough to ensure atlanto-axial mechanical stability.

High definition computed cervical myelograms have been made in flexion and extension in 13 patients with Morquio-Brailsford's disease. We observed that: 1) odontoid dysplasia was present in every case, with a hypoplastic dens and a detached distal portion which was not always ossified; 2) atlanto-axial instability was mild, and anterior atlanto-axial subluxation was absent in most cases; 3) severe spinal cord compression, when present, was due to anterior extradural soft-tissue thickening; 4) this compression was not relieved by flexing or extending the neck and was manifested early in life; 5) posterior occipitocervical fusion resulted in disappearance of the soft-tissue thickening and normalisation of subsequent development of the dens. We conclude that the severity of neurological involvement at the craniovertebral junction was determined by soft-tissue changes, not by the type of odontoid dysplasia nor by subluxation. Posterior occipitocervical fusion proved to be an effective treatment.

Cervical myelopathy is an uncommon but potentially fatal complication of rheumatoid atlanto-axial subluxation. Computerised myelotomography with three-dimensional reconstruction shows that rheumatoid pannus, together with the odontoid peg, contributes significantly to anterior cervico-medullary compression. These findings were the basis for treatment by transoral anterior decompression and posterior occipitocervical fusion, which removes both bony and soft-tissue causes of compression and allows early mobilisation without major external fixation. We report encouraging results from this combined approach in 14 patients who had progressive neurological deterioration.