Morphological changes of the multifidus muscle in patients with symptomatic lumbar disc herniation.

OBJECT

Lumbar disc herniations are associated with segmental muscle alterations of the ipsilateral segmental multifidus muscle. The aim of the present study was a histopathological analysis of the myopathological changes of the multifidus muscle and correlation with the duration of radicular symptoms.

METHODS

Multifidus muscle biopsies were performed in 20 patients during discectomy. Specimens were obtained from the area of the multifidus muscle innervated by the nerve from the level of the affected disc. Histopathological findings were classified according as neurogenic tissue syndrome and nonspecific myopathological syndrome, and these results were correlated with the duration of radicular symptoms.

RESULTS

Results of multifidus muscle biopsies were classified as neurogenic tissue syndrome in 12 patients and as nonspecific myopathological syndrome in 8. The mean (+/- SD) duration of radicular symptoms was 10.75 +/- 7.9 months in patients with neurogenic tissue syndrome and 4.37 +/- 3.9 months in patients with a nonspecific myopathological syndrome. There was a positive correlation between group assignment and symptom duration (correlation coefficient 0.457, p = 0.043).

CONCLUSIONS

A long duration of radicular symptoms is associated with a neurogenic tissue syndrome, whereas a nonspecific myopathological tissue syndrome is seen in patients with shorter duration of symptoms. This suggests that patients with long duration of radicular symptoms originating from a lumbar disc herniation have an increased risk for neurogenic muscular changes, and that consideration should be given to an earlier surgical intervention.