Linguistic perseveration in dominant-side intracarotid amobarbital tests.

148 patients with medically intractable complex-partial seizures received bilateral intracarotid amobarbital tests. In 21 patients (14.2%), there were inappropriate responses (intrusions: N = 10; perseverations: N = 11) to a series repetition task (counting backwards) given immediately before amobarbital injection. Five cases from the perseveration subgroup are discussed in detail. In these patients, linguistic perseveration occurred with left-sided amobarbital injection, although they were all found to have left hemispheric speech dominance according to language testing during the amobarbital procedure. It is argued that these perseverations are best explained as a right hemispheric continuation of a speech motor program previously initiated by the left hemisphere.