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 cerebral artery (PCA) territory infarcts. Typically, however, reading is not assessed in epilepsy surgery candidates who undergo left posterior cerebral artery sodium amytal (PSA) testing. We present clinical observations of three right-handed subjects who demonstrated transient alexia (letter-by-letter reading) when presented a compound word in the intact visual half-held during left PSA [with posterior left hemisphere amytal distribution verified by single photon emission computed tomography (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 subjects also demonstrated object naming failures to visual and tactile confrontation. Color naming, sentence repetition, serial speech, and auditory comprehension were preserved in all three cases; i.e., patients developed only one (anemia) or no other neighborhood signs. Although limited by the number of data points, this case series suggests that reading items might be beneficially incorporated into the PSA test. Whether the occurrence of dyslexia during dominant hemisphere PSA testing has predictive validity in identifying patients at risk for postoperative reading impairment remains to be investigated.