Trans-synaptic transport of tetanospasmin and consequent inhibition of neurotransmitter release in spinal neurons is responsible for the major physiological manifestations of tetanus. Inhibitory neurons are more affected than excitatory neurons. Inhibitory neurons are responsible for modulation of excitatory signals from higher centers and local reflex arcs. Loss of this inhibition leads to both a higher firing rate in the lower motor neuron and a loss of reflex relaxation of antagonistic muscle groups during movement. The effects on the a motor neuron are an increased basal tone, manifesting clinically as rigidity. Clinically, spasms are the result of exaggerated uncoordinated reflex responses to minimal stimuli.
Was this article helpful?