[Microsurgery of acquired degenerative lumbar spinal stenosis. Bilateral over-the-top decompression through unilateral approach].

Degenerative lumbar spinal stenosis is diagnosed with an increasing incidence. Clinical and radiological signs of progression often result in a significant decrease in the patient's quality of life. The indication for surgical treatment follows the spectrum of clinical symptoms. In cases with "structural" spinal stenosis and predominant "leg symptoms" such as neurogenic claudication and/or radicular symptoms, decompressive types of surgery are indicated. However, due to the multimorbidity of the mostly elderly patients, the surgical risk should be as low as possible whereas the surgical efficacy should be as high as possible. We describe a microsurgical technique, which can achieve a bilateral decompression of the central and lateral lumbar spinal canal through a unilateral surgical approach. In a consecutive series of 275 patients, a significant increase in standing time and walking distance could be attained. The surgical complication rate was low. A complete decompression of the spinal canal with preservation of the "tension band" of the posterior spinal column could be achieved. Although this type of surgery is adequate for patients with "predominantly leg symptoms" only, low back pain improved as well in nearly 50% of the patients. However, in cases with dynamic spinal stenosis and/or disturbed curvature with predominant low back pain, a combination of the described procedure with stabilizing surgery (spinal fusion, dynamic fixation etc.) is recommended.