Smith-Petersen vitallium mould arthroplasty: a 45-year follow-up.

THE JOURNAL OF BONE AND JOINT SURGERY tions, including 24-hour ambulant monitoring, revealed only atrial fibrillation. Radiographs of the cervical spine showed spondylolisthesis at the C5 to C6 level. Anterior cervical interbody fusion was performed at this level; the bony changes seen at operation were similar to those described in case 1. He had no more drop attacks during the last year of his life. Discussion. We describe two elderly men who had drop attacks and cervical spine instability. In both cases the attacks ceased after limited fusion of the cervical spine. We cannot prove that compression of the vertebral artery was the cause, but this seems likely because of the good results of fusion. Any fracture or dislocation of the cervical spine above the sixth cervical intervertebral foramen may compromise the vertebral arteries, and relative vascular insufficiency may occur in the basilar artery and its branches as well as in the anterior cervical artery. Both our patients were elderly which may explain why the collateral circulation, from the circle of Willis, was not sufficient to compensate for the diminished flow in the vertebral arteries when flexion of the cervical spine led to subluxation. In elderly subjects with unexplained drop attacks instability of a degenerate cervical spine should be considered since surgery may prevent these symptoms.