Pure word deafness due to left subcortical lesion: Neurophysiological studies of two patients

Objective This study investigated the auditory processing in two patients with pure word deafness (PWD) using neurophysiological experimental methods. Methods We recorded the auditory brainstem response (ABR), the middle latency auditory-evoked response (MLR) and the auditory-evoked event-related potentials (ERPs) in two patients with PWD after subcortical hemorrhage in the left temporal lobe. Results Both patients showed normal response in ABR and abnormality in MLR. The latency of P300 evoked by right-ear stimulation was 51 ms longer in one patient and 26 ms longer in the other patient than that evoked by left-ear stimulation. Conclusions Our results suggested that the prolongation of P300 latency could be caused by the deterioration of auditory stimulus processing and supported the hypothesis that the defect in auditory temporal resolution was an important factor in the development of PWD. Significance This study demonstrated that recordings of ERP with auditory-evoked response such as ABR and MLR are useful to elucidate the deterioration of auditory stimulus processing in patients with PWD.