[Knotted neurinoma or plexiform neurofibroma in the cauda equina (author's transl)].

A rare case of a plexiform neurofibroma in the cauda equina is reported. In literature single cases are described as "redundant or knotted nerve roots", but mainly without microscopic description. Our patient was complained of bilateral pain in the legs for several years. The myelogram revealed a complete block with a serpentine-shaped structure. In operation we found a elongated and redundant nerve root in the cauda equina. The biopsy showed a plexiform neurofribroma. The operative technique is described.