Microsurgical posterolateral transmuscular approach for lumbar foraminal stenosis.

STUDY

DESIGN

Retrospective review of 39 consecutive patients who underwent surgery for lumbar foraminal stenosis from 2004 to 2009.

OBJECTIVE

To evaluate the surgical technique and results of microsurgical posterolateral transmuscular approach for lumbar foraminal stenosis. In addition, to evaluate the diagnostic ability of coronal thin-sliced magnetic resonance imaging (MRI) for this disease.

SUMMARY OF BACKGROUND DATA: Lumbar foraminal stenosis is a disease caused by compression of the nerve root or dorsal root ganglion at the intervertebral foramen often causing severe sciatic pain. Although its diagnosis and surgical treatment has been described in the literature, posterolateral transmuscular approach has not been well described. In addition, definitive radiologic diagnosis of this disease is often difficult, which can lead to failed back syndrome.

METHODS

We retrospectively reviewed 39 consecutive patients who underwent surgery for lumbar foraminal stenosis from 2004 to 2009. Special thin-sliced coronal MRI was used for preoperative evaluation. Microsurgical posterolateral transmuscular approach was used to decompress the intervertebral foramen from the lateral side preserving most of the pars interarticularis and facet joint. Contralateral medial approach was used for cases with associated central canal stenosis. Surgical results were scored using MacNab scale. We compared the sensitivity and specificity of 2 MRI signs: (1) abnormal course of the nerve root inside the foramen on coronal slices, and (2) obliteration of the foramen on sagittal slices, and statistically analyzed them with the χ method.

RESULTS

The MacNab score with the mean follow-up period of 25.5 months was excellent in 28 (72%), good in 5 (13%), fair in 3 (8%), and poor in 3 (8%) patients. There was no grave complication. Coronal MRI sign showed significantly better sensitivity and specificity.

CONCLUSIONS

Posterolateral transmuscular approach with microsurgical foraminotomy provided excellent surgical results. Coronal thin-sliced MRI can be useful for diagnosis of this disease.