Cervical myelopathy in patients with congenital cervical block vertebrae.

Thirty-two patients with congenital cervical block vertebrae are reviewed. Twenty-nine patients had single level fusion, one had two-level fusion, and the remaining two had multilevel fusion. Eighteen patients had cervical myelopathy; five of these had related trauma and 13 had no history of trauma. The five patients who had cervical myelopathy following trauma underwent magnetic resonance imaging (MRI); three of them had abnormalities in the spinal cord at the segment adjacent to fusion. In all five patients the symptoms and signs were attributed to the segment adjacent to fusion. Myelography, computed tomographic myelography and MRI were performed in 11 of the 13 patients with cervical myelopathy without trauma. In 9 of them maximum compression of the spinal cord was not seen at the segment adjacent to fusion. The major factor contributing to cervical myelopathy was associated spinal canal stenosis. Seven patients with cervical myelopathy without history of trauma were treated surgically, six of whom had spinal canal stenosis treated by enlargement of the spinal canal: subtotal corpectomy and arthrodesis was performed in three, and open-door expansive laminoplasty in three. Anterior interbody arthrodesis was performed in one patient without spinal canal stenosis. All recovered from the myelopathy postopera-tively. When a trauma occurs, it concentrates stress at the segment adjacent to fusion, resulting in possible spinal cord injury. On the other hand, when there is no trauma, spinal canal stenosis is the principal factor contributing to cervical myelopathy.