Microsurgical extraforaminal decompression of lumbar root canal stenosis
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Mayer, München Zeichner
R. Himmelhan, Heidelberg
Introductory remarks Disc degeneration and facet joint arthritis result in degenerative changes, all at the costs of the space in the spinal canal and foramina, thus contributing to spinal ste nosis, be it lateral, central, or both. The lumbar root canal looks like an alphorn which becomes longer and more oblique in the craniocaudal direction (. Fig. 1) A bit arbitrary the canal can be divided in a subarticular, foraminal, and extraforami nal part. We assume that the narrowing of the root canal can be caused by altera tions of the anatomical structures border ing the canal itself or by a spatial disloca tion of these structures [1, 3, 4]. Nerve entrapment in the canal may be caused by non-disc material, such as the following: F capsular “hypertrophy” or buckling (. Fig. 2), F superior facet subluxation (. Fig. 3), F pedicular kinking (. Fig. 4), F spondylolisthesis, and F narrowing of the gap between the transverse process L5 and ala (. Fig. 5). The narrowing of the subarticular part of the canal is addressed in a separate manuscript [9], while this manuscript focuses on extraforaminal non-disc im pingement of the lumbar nerve. Typical of this syndrome is claudicant unilateral radicular leg pain (chronic radicular syn drome) and the frequent absence of hard neurologic findings. Back pain may be a part of the complaints, but it is the chronic leg pain which is disabling.
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L. Papavero · R. Kothe Clinic for Spine Surgery, Schoen Clinic Hamburg Eilbek
Microsurgical extraforaminal decompression of lumbar root canal stenosis The leg pain follows more a definite radicular distribution than the diffuse leg discomfort seen in spinal canal steno sis. It is aggravated by standing and walk ing and decreases slowly by sitting or after cessation of the aggravating activity. Per formance of straight leg raising (SLR) test is not reduced to any great extent.
Surgical principle In the same manner that the interlaminar window allows access to be gained to the subarticular or lateral recess stenosis, the intertransverse interval approached by a paraspinal muscle-splitting route allows access to the extraforaminal part of the nerve canal. In the intertransverse interval, the lateral border of the pars interarticularis is on the same sagittal plane as the medial border of the pedicle (except for L5). Find the pedicle and medial to it will be the nerve.
Advantages F Facet joint and yellow ligament are mostly preserved F Pedicle screw fixation and fusion of the target segment are avoided, pro vided that the indication is appropri ate F Avoiding scar tissue when dealing with persistent leg pain in patients previously decompressed via an inter laminar route
Operative Orthopädie und Traumatologie 1 · 2013
Prerequisites F Very lateral sagittal T2-weighted MRI slices necessary for surgical planning F Substantial surgical experience should already have been acquired treating extraforaminal disc hernia tions F Bayoneted micro-instruments, thin
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