Drop attacks and instability of the degenerate cervical spine.

©1996 British Editorial Society of Bone and Joint Surgery 0301-620X/96/3R65 $2.00 J Bone Joint Surg [Br] 1996;78-B:495-6. Received 31 July 1995; Accepted 1 September 1995 For many years, drop attacks in elderly patients have been associated with compression of the vertebral artery with brain-stem and cerebellar dysfunction (Schneider and Crosby 1959). It has been suggested that the pathological mechanisms involved are traumatic dissection and compression caused by subluxation, fractures and cervical spondylosis (Sheehan, Bauer and Meyer 1960; Mas et al 1987Jabre 1991. We report two elderly subjects with drop attacks which were probably due to instability of a degenerate cervical spine. Case 1. An 85-year-old man had been suffering for ten years from drop attacks which occurred without warning and without loss of consciousness. After each fall, he had confusion, dysarthria and transient tetraparesis lasting for only a few minutes. A cardiovascular cause was suspected because of a heart attack in the past, but several investigations including 24-hour ambulant monitoring failed to show any cardiac aryhythmia even during an attack. At a routine examination, extensor plantar reflexes were found. After one drop attack in which his neck was struck, cervical flexion at examination provoked another fall from which he recovered completely in about a minute. It was uncertain whether earlier drop attacks had been provoked by cervical flexion, but radiographs showed extreme instability at the C5 to C6 level (Fig. 1), especially during flexion. Anterior cervical interbody fusion was performed one week later. At operation it was obvious that the instability had existed for much longer than a few weeks. The vertebral bone was smooth, very hard and contained a cyst. Since his fusion, 3.5 years ago, he has had no drop attacks.