Purpose: Course and pathophysiology of a typical syndrome after irradiation of the cauda equina were studied.
Patients and materials: 7 patients with irradiation damage of the cauda equina were examined clinically and neurophysiologically.
Results: After a mean delay of 5 years and 6 months all patients developed an ascending lower motor neuron weakness of the legs without pain, in part accompanied with mild sensory and sphincter symptoms. Electromyography, evoked potentials and neurography were important for the differential diagnosis to tumor infiltration. The course was progredient.
Discussion: For a long time, the underlaying damage was thought to be in the anterior horn cell body. The course of the studied patients with additional sensory and vegetative symptoms implies for a direct bilateral damage of the cauda equina. A better term for the syndrome is "post-irradiation cauda-equina-syndrome".