Surgical correction of cervical hyperextension in rigid spine syndrome.

The rigid spine syndrome is a condition characterized by a mild axial and proximal myopathy in which the fibrous shortening of spinal extensor muscles causes a marked limitation in flexion of the spine. This 10-year-old boy with rigid spine syndrome showed a progressive limitation in flexion of the cervical spine with fixed hyperextension of the neck. To look forward he had to bend forward his trunk flexing hips and knees. An X-ray study demonstrated a progressive limitation in flexion but also in extension of the cervical spine. A particular radiologic aspect named "Alligator sign" was demonstrated. The hyperextension of the neck was corrected surgically by opening the interspinous spaces from C2 to C7 through a capsulotomy. The correction was stabilized with bone grafts fixed to the spinous processes. This boy with the straightened cervical spine was then able to look forward without any compensatory posture.