Chemical Agents of Opportunity for Terrorism: TICs & TIMs

Chemical Agents of Opportunity for Terrorism
Training Support Package
Participant Guide
Slide 7
Chemical Agents of Opportunity for Terrorism:
TICs & TIMs
Clinical Syndromes of the CNS
Too much stimulation = Convulsions
Excitation
Inhibition
Module Two - The Clinical Neurotoxicology of Chemical Terrorism
7
While chemicals (and drugs) may cause convulsions by enhancing excitation, a more
common mechanism for intoxicant-induced convulsions is diminished inhibition (known
as “inhibition of inhibition”).
A convulsion occurs when the patient has repetitive and uncontrolled jerking of the
extremities. This is sometimes referred to as a seizure. However, a seizure refers to
abnormal electrical activity in the brain, while convulsions refer to the abnormal muscle
activity we are able to observe. Not all convulsions are seizures – the best example
being the effects of strychnine, where the patient is awake and aware, but unable to
control his muscle movements. Convulsions are often violent and may result in injury to
the patient. In addition the intense muscle activity may result in an elevated body
temperature and muscle damage. Prolonged seizures (those lasting more than 30
minutes) or repetitive seizures without recovery of consciousness are termed status
seizures. These can cause permanent brain injury and can lead to death.
Patients having seizure are often unaware of their movements and may not even be
aware that they are having a seizure. Prior to the onset of convulsions the patient may
exhibit tremors and jitteriness. There are many different causes of seizures. Epilepsy is
one of the most common causes. Epilepsy is not caused by specific drugs or toxins and
usually develops in childhood. There are a large number of drugs and toxins that can
also cause seizures.
Note the see-saw is tilted towards excitation. The boxes depict both increased excitation
and decreased inhibition (compared to baseline).
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