Innervation of the spondylolysis "ligament".

SUMMARY OF BACKGROUND DATA: Spondylolysis of the lower lumbar vertebrae is a non-united childhood fracture of the arch of the vertebra, persisting into adult life. Symptoms of disabling low back pain appear in a minority of patients, usually for the first time in adulthood. This pain is considered to arise from several separate sources, one of which may be the spondylolysis ligament.

STUDY DESIGN: The innervation of the ligament has been investigated immunohistochemically.

METHODS: Specimens from eight patients were divided longitudinally for histology including hematoxylin and eosin, toluidine blue, and elastic van Gieson. Histochemistry involved immunostaining for the neuropeptides: protein gene product, calcitonin gene related peptide, substance P, vasoactive intestinal peptide, and the c-flanking peptide of neuropeptide Y.

RESULTS: Immunoreactivity to calcitonin gene-related peptide, the c-peptide of neuropeptide Y, and vasoactive intestinal peptide was identified in the ligament or in the adjacent adipose tissue.

CONCLUSION: The movement that the ligament allows at the fracture site may result in stimulation of the nerve endings both in the ligament and in the surrounding soft tissue.