Rigid spine syndrome. A type I fiber myopathy.

The rigid spine syndrome is an unusual disorder characterized by nonprogressive mild axial and proximal muscle weakness, flexion contractures of the neck and spine, scoliosis, and joint contractures. The biopsy specimen from the patient described in this report shows type I fiber hypotrophy and predominance. This contrasts with previous reports that describe connective tissue proliferation as the major histologic abnormality.