Alternating sciatica while jogging: an early symptom of cauda equina tumor.

Three athletic patients with cauda equina or lumbosacral cord tumor noticed, as an early symptom of the disease, alternating bilateral sciatica synchronized with each stride while jogging. Comparison with athletic patients who developed lumbar disc hernia suggested that this symptom was significant. The authors speculated that the mechanism producing this symptom is the inertial force induced while jogging, which acts on the tumor in its early stage, when it is still quite mobile in the intradural space. The diagnostic role of this symptom in cauda equina and lumbosacral cord tumor should be recognized.