Developmental asymmetry of roots of the cauda equina at metrizamide myelography: report of seven cases with a review of the literature.

The myelographic findings of developmental asymmetry of the lumbo-sacral nerve root sheaths are described in seven patients and details of the clinical presentation and management are presented. Six of the seven patients had referred pain to the leg on the side of the anomaly. There were no significant associated plain film findings. Adherence to recommended techniques of metrizamide myelography is stressed, with particular reference to horizontal beam decubitus oblique projections, which profile the root sheaths to best effect. Minimal signs in the frontal projection are also described, which may be the initial clue to diagnosis. The possibility of erroneous diagnosis of lateral disc protrusion is emphasised if this anatomical variant is not recognised.