Subarticular entrapment of the dorsal root ganglion as a cause of sciatic pain.

Eleven patients who presented with sciatica that was aggravated by standing and walking had definite neurologic signs in only half the cases and normal myelograms in seven. Differential blocks of the L4, L5, and S1 nerve roots identified the symptomatic levels by temporarily relieving the pain in all patients done. CT scans showed minimal enlargement of the articular facets, but an absence of periradicular fat and an increased volume of neural tissue due to the presence of proximally placed dorsal root ganglia in the nerve root canal. Decompression of the symptomatic ganglia by surgical removal of the medial third of the overlying apophyseal joint resulted in satisfactory pain relief in 70% of these patients.