FoundationalConceptsNeuroscience

or the smell of an unusual odor. There may be rapid and inexplicable
emotional or cognitive changes. There are often involuntary muscle
movements, and sometimes even complete loss of control over the
movement of one’s body. Obviously, this could lead to serious con-
sequences if someone has a seizure while, for example, driving a car.
Amnesia, or memory loss, frequently accompanies the experience of a
seizure. Severe seizures can produce a loss of consciousness and even
death. Too much excitation is not a good thing.
Sometimes seizures are associated with particular identifiable
causes. A tumor—an abnormal growth of cells in the brain—may
disrupt neural circuitry, producing unbalanced excitation. New onset
of seizures in an adult is always reason to check for the existence of
a brain tumor. Brain infections and high fevers may trigger seizures.
Traumatic physical injury to the head, such as from a car or bicycle
accident, may disrupt the neural connectivity in such a way that
seizures are a result. Drugs that increase brain neuronal excitability
(stimulant drugs are discussed in Chapter 9) have the potential to
produce seizures. Some drugs that produce the opposite effect of stim-
ulants, inhibiting neural activity in the brain, can also increase the
risk for seizures if these drugs are used regularly and then abruptly
stopped. Examples of such drugs are alcohol and other sedative-hyp-
notics, also discussed in Chapter 9.
Most seizures, however, have not been associated with any identi-
fied causes. These are called idiopathic seizures. Idiopathic is a word
widely used in medicine. It means that the condition arises from an
obscure or unknown cause. The roots are from the Greek idios, mean-
ing personal, private, separate, and pathos, meaning suffering.
Idiopathic seizures may appear spontaneously at any point in life,
although they most often first appear in childhood. There are genetic
and developmental components to idiopathic seizures, although these