Chemical Agents of Opportunity for Terrorism: TICs & TIMs

Chemical Agents of Opportunity for Terrorism
Training Support Package
Participant Guide
Slide 25
Chemical Agents of Opportunity for Terrorism:
TICs & TIMs
Clinical Syndrome: Convulsions
Excitation Inhibition
Module Two - The Clinical Neurotoxicology of Chemical Terrorism
25
The second clinical syndrome to discuss is convulsions/seizures. A seizure really refers
to brain activity whereas convulsion is what you see when you look at the patient - that is
the movement itself. Some convulsant toxins are not seizure inducing. An example is
strychnine.
These words – seizure and convulsion – are sometimes used interchangeably – but as
noted before – a seizure refers to the abnormal electrical activity that occurs in the brain
and is usually manifested by violent rhythmic movements of the extremities while
convulsions only refer to these abnormal movements. Strychnine does not cause
abnormal electrical activity in the brain. Strychnine only effects neural impulse
transmission in the spinal cord which also happens to cause convulsive movements of
the extremities. Hence strychnine poisoning causes convulsions without seizures.
Robin Cook’s medical novel, Seizure, is used here just as a graphic depiction of a nerve
synapse (nerve-to-nerve communication).
The see-saw depicts a tilt towards the excitatory side. Note that the major reason for this
imbalance is a decrease in inhibitory input.
December 2008 Version 2.0 Page 93