Dominant-side intracarotid amobarbital spares comprehension of word meaning
J. Hart Jr, R. P. Lesser, R. S. Fisher, P. Schwerdt, R. N. Bryan and B. Gordon
Department of Neurology, Johns Hopkins University, Baltimore, Md.
Abolition of speech production after intracarotid amobarbital injection is
generally considered evidence for language laterality. However, complex
auditory comprehension may be preserved after injection of the dominant
(left) side. The possibility that this sparing may be due to the
intracarotid amobarbital injection not adequately deactivating some of the
areas responsible for speech comprehension in the posterior part of the
hemisphere was tested with a task known to be critically dependent on the
left posterotemporal-inferoparietal region, one assessing visuo-verbal
semantic relatedness. Even when the intracarotid injection of the left side
produced marked deficits of speech production, comprehension of semantic
relations was still intact in eight of 15 patients. Ten of these 15
patients also received right carotid injections, none of which affected
comprehension of semantic relatedness. These data indicate that the
intracarotid amobarbital injection cannot always specify the laterality of
all language functions, an important concern when considering surgical
procedures in the dominant posterotemporal-inferoparietal region.
