Postradiation lower motor neuron syndrome: case series and literature review

Abstract

A variety of neurological syndromes has been described after irradiation of the distal spinal cord and cauda equina, mainly as treatment for testicular cancer and lymphoma. One of these syndromes is a rare lower motor neuron syndrome, manifested by flaccid paraparesis. Medical files of patients with postradiation lower motor neuron syndrome treated in our neuromuscular clinic from 2005 to 2012 were reviewed. The diagnosis was based on past irradiation of the distal spinal cord and cauda equina, slowly progressive lower limb weakness, characteristic electrophysiological studies, and no alternative diagnosis. In addition, a systematic review of the literature on similar cases was performed using PUBMED. We identified five patients with postradiation lower motor neuron syndrome in our clinic charts. Three of them were irradiated due to seminoma, and the other two due to lymphoma. 45 additional similar cases were found in a literature search, mainly male (89 %), with testicular cancer (67 %), irradiated at mean age of 33 years, with an average irradiation dose of 5,225 cGy (range 3,000-14,600), and a latency period between irradiation and symptoms onset ranging from 3 months to 27 years (average 9 years). Magnetic resonance imaging was done only in few, showing gadolinium enhancement of the cauda equina in close to half of them (7/16). Our patients and those previously described in the literature form a distinct clinical and electrophysiological syndrome that might be more frequent then previously expected, and should be not overlooked.