Anatomic and radiographic study of dorsal root ganglia.

Anatomic and radiographic studies were made to investigate normal variation of dorsal root ganglia in lumbosacral roots. The spinal nerves could be divided into two groups, with and without bifurcation of ventral nerve root and dorsal root ganglion. The bifurcated group was further classified into three types. L4 and L5 nerve roots were all bifurcated, and S1 were all nonbifurcated. The positions of dorsal root ganglia were classified into three types: intraspinal, intraforaminal, and extraforaminal. At L4 and L5 nerve roots, they were mostly intraforaminal, whereas at S1, they were mostly intraspinal. Proximally placed ganglia had a high frequency of ganglionic indentation. The incidence of intraspinal dorsal root ganglia was much higher clinically than in anatomic studies. Variations in connecting patterns or positions of dorsal root ganglia may be related to the occurrence and variety of radicular symptoms. The dorsal root ganglia is clinically important, and its location may correspond to clinical symptoms.