STENOSIS OF THE LUMBAR SPINE - AN UPDATE 50 YEARS AFTER THE 1ST DESCRIPTIONS

About 50 years after the first descriptions of lumbar stenosis and its most frequent symptom, neurogenic intermittent claudication, this upd ate gives an overview of present-day concepts of the disease and of ne w experience in this area. Stenosis of the central and lateral lumbar spine is chiefly held to be one of the results of segmental degenerati ve instability throughout the several stages of spondylosis. The degen erative process of the spine has its starting point in regressive chan ges of the disc. This leads to instability of the motion segment, whic h explains the pathophysiological dynamics of the stenosis and its sym ptoms, including intermittent neurogenic claudication. Segmental insta bility is the crucial lesion causing all the changes in the degenerati ve process, which are not to be considered as separate entities but as part of the dynamics of the same disease. The spine's congenital anat omic individual patterns, which conferm the population thinking of the evolutionary biology (since they are different from one motion segmen t to the other) help to determine the outline of single cases. The dis parity between radiological and clinical patterns is pointed out: seve re stenosis may be asymptomatic or cause just modest monoradicular tro uble as well as serious multiradicular deficit. The reason for the dis crecpancy is unknown. One must be careful to avoid surgery on a silent , purely radiological stenosis. Experience of more than 15 years confi rms the uselessness of performing a complete laminectomy to achieve su fficient decompression. The author's method of selective decompression is described briefly. The English term ''undercutting decompression'' runs the risk of being misunderstood, since it is also used for rathe r destroying procedures. Finally, we point out that surgery for spinal stenosis must resolve both root compression and degenerative instabil ity in the majority of cases. In most cases of lumbar stenosis, if dec ompression alone is performed, only the consequence, and not the cause of the disease, segmental degenerative instability, is treated. Osteo phyte formation is an attempt by nature to stabilize the motion segmen ts by stiffening its components. Spinal fusion tries to achieve the sa me effect. For most cases of spinal stenosis, we suggest our own techn ique, which combines safe and preserving (''selective'') decompression according to Benini [1, 7] with the translaminar screw fixation of Ma gerl [7]. In cases of degenerative spondylolisthesis, however, transpe duncular fusion is mandatory.