Failed lumbar disc surgery: cause, assessment, treatment.

The challenge of failed back surgery is in the decision of when to operate and how to do it competently. Specific neuroanatomic indications as a basis for surgical treatment should reduce surgical failures. One source of failure is a "battered root" and the arachnoiditis which may follow limited or inadequate interlaminar exposure. Even with adequate interlaminar exposure, hemostasis may be difficult if preoperative positioning of the patient to diminish intra-abdominal pressure has not been performed. Bleeding can obscure the operative field and the surgeon's ability to visualize and deal with the problem at hand. A less common cause of failure is segmental instability. This may be pre-existing and related to facet tropism. It may also be a consequence of surgical removal of posterior vertebral elements, thus creating a loss of stability with or without a discernable change in vertebral alignment. The surgeon should try to: avoid becoming enmeshed in the psychodynamic problems of patients. He should use specific diagnostic tests, e.g., nerve blocks or facet injections, in an effort to localize specific sources of pain; recognize that prognosis is adversely affected by additional surgery; and avoid "exploratory" operations. Furthermore, neurolysis without spatial decompression, bony or otherwise, is eventually futile. All patients with failed back surgery have a psychodynamic component to their pain. This article will have achieved its purpose if it promotes recognition that a small percentage of patients with failed back surgery can be helped. These are individuals in whom specific diagnostic tests or clinical acumen uncover a surgically correctable lesion, be it compressive or radiculopathy or segmental instability. In such instances an adverse psychologic profile need not necessarily be a deterrent to surgical treatment.