Chapter 18 Toxic disorders of the upper motor neuron system

Area of Science:

• Neuroscience
• Toxicology
• Neurology

Background:

• Lathyrism and konzo are debilitating neurological disorders.
• Both conditions result from prolonged dietary reliance on specific neurotoxic foods: grass pea for lathyrism and improperly processed bitter cassava for konzo.
• Poor nutrition and excessive exercise are identified as significant risk factors.

Purpose of the Study:

• To elucidate the neurobiological mechanisms underlying lathyrism and konzo.
• To understand the differential vulnerability of motor neurons in these toxic neuronopathies.
• To identify the etiological factors and potential therapeutic targets.

Main Methods:

• Review of experimental studies on lathyrism and konzo.
• Analysis of neurotoxicological data from grass pea (BOAA) and cassava (SCN, OCN).
• Examination of primate models of lathyrism.

Main Results:

• Lathyrism and konzo are characterized by spastic paralysis of the lower extremities, potentially affecting upper limbs and causing pseudobulbar dysfunction in severe konzo cases.
• Experimental evidence suggests these are primary neuronopathies affecting upper motor neurons bilaterally.
• Cortical motor neurons with the longest axons appear most vulnerable, likely due to glutamate receptor interactions with neurotoxins.

Conclusions:

• Lathyrism and konzo represent toxic neuronopathies affecting the corticospinal tract.
• The severity and specific presentation depend on the causative agent and duration of exposure.
• Further research into neurotoxin mechanisms and nutritional support is warranted.