[Spastic paraparesis due to long term consumption of wild cassava (Manihot esculenta): a neurotoxic model of motor neuron disease].

INTRODUCTION: Cassava (Manihot esculenta) is the basic foodstuff of more than 500 million persons in developing countries. Its edible root contains a glucoside with a high cyanogenic content, linamarina, which is hydrolysed in the human intestinal tract by the resident microbial flora, with liberation of HCN. Inadequate preparation and cooking followed by consumption whilst half-raw, especially in diets based almost exclusively on cassava for a long period of time, may lead to a neurological syndrome of damage to the upper motor neuron and the appearance of spastic paraparesia.

CLINICAL CASE: We present the case of a 44 year old male agricultural worker from the Amazon region who had a predominantly crural spastic paraparesis which had been present for four years. His main food was 'mandioca brava' or wild cassava which was insufficiently cooked. Study of the CSF ruled out infection by HTLV and neurosyphilis. On magnetic resonance there was slight thoracic atrophy.

CONCLUSIONS: In patients with spastic paraparesis, normal neuroimaging and CSF findings, and a normal family history, one should specifically investigate exposure to potentially toxic plants and foods, especially in regions in which nutrition is based on potentially cyanogenic roots or plants. It is necessary to improve the methods of processing and cooking cassava, and to avoid diets based almost entirely on this root, in order to reduce the potential neurotoxic damage which may be caused by this plant.