Ischemia causes transient focal neurologic symptoms [i.e., transient ischemic attacks (TIAs)] due to diminished blood flow to a focal brain region (see Chapter 52, Examination of the Patient with a Probable Stroke). By definition, a TIA is transient ischemia; a TIA that doesn’t resolve is called a stroke.

Partial (also called focal) seizure disorders cause transient focal neurologic symptoms due to focal cortical epileptic activity. Partial seizures that do not impair consciousness are called simple partial seizures. Partial seizures that impair consciousness (such as many temporal lobe seizures) are called complex partial seizures. Partial seizures may spread to involve the whole brain, causing a secondarily generalized seizure (in contrast to a primary generalized seizure, which begins simultaneously on both sides of the brain and does not have a focal onset or focal symptomatology).

Migraine can cause transient focal neurologic symptoms; the pathogenesis of migrainous neurologic symptoms is uncertain but may be due to a slowly spreading wave of depolarization called spreading cortical depression.