TRANSIENT ALEXIA (LETTER-BY-LETTER READING) AFTER SINGLE-PHOTON EMISSION COMPUTED TOMOGRAPHY-VERIFIED SELECTIVE LEFT POSTERIOR CEREBRAL-ARTERY SODIUM AMYTAL INJECTION

Alexia characterized by letter-by-letter reading is an acquired visual word-form dyslexia which has been observed after left posterior cereb ral artery (PCA) territory infarcts. Typically, however, reading is no t assessed in epilepsy surgery candidates who undergo left posterior c erebral artery sodium amytal (PSA) testing. We present clinical observ ations of three right-handed subjects who demonstrated transient alexi a (letter-by-letter reading) when presented a compound word in the int act visual half-field during left PSA [with posterior left hemisphere amytal distribution verified by single photon emission computed tomogr aphy (SPECT)]. In all three cases, the sodium amytal effect persisted throughout language testing, as evidenced by hemianopia contralateral to the side of injection. In addition to alexia, two of the three subj ects also demonstrated object naming failures to visual and tactile co nfrontation. Color naming, sentence repetition, serial speech, and aud itory comprehension were preserved in all three cases; i.e,, patients developed only one (anomia) or no other neighborhood signs. Although l imited by the number of data points, this case series suggests that re ading items might be beneficially incorporated into the PSA test. Whet her the occurrence of dyslexia during dominant hemisphere PSA testing has predictive validity in identifying patients at risk for postoperat ive reading impairment remains to be investigated.