A Case of Generalized Auditory Agnosia with Unilateral Subcortical Brain Lesion
A 73-year-old right handed male presented to emergency room with the sudden onset of right hemiplegia and dysarthria. He was diagnosed as having intracranial hemorrhage of the left basal ganglia and temporal lobe. After 3 weeks, he was offered rehabilitation services for the auditory problem of being unable to differentiate voices, music, and environmental sounds. His past medical history included hypertension and right basal ganglia intracranial hemorrhage 13 years previous. There has been no definite sequelae of previous stroke. In the neuroimaging studies 2 weeks after the onset of the stroke, a non-contrast computed tomography (CT) scan and magnetic resonance imaging (MRI) showed intracranial hemorrhage of the left basal ganglia and temporal lobe area and a single photon emission computed tomography (SPECT) showed a moderate to severe perfusion decrease and impaired vascular reserve in left temporal lobe ().\nHe was an alert patient but, he did not follow oral commands or respond to environmental sounds. His verbal repetition and writing to dictation were severely defective with phonemic substitutions. Neuropsychological evaluations were performed 3 weeks after the onset of stroke. He obtained a score of 4/30 on the Mini Mental State Exam of Korea (MMSE-K) with verbal communication. He was diagnosed as having cognitive dysfunction. But he could comprehend written and gestural communication. A language assessment using the Korean Version of the Western Aphasia Battery (K-WAB) revealed that he had significant deficits in auditory comprehension, repetition, and writing to dictation, despite the presence of good reading, fluent speech, and spontaneous writing, without evidence of aphasia. He could speak complete sentences without paraphasia. The Token test was 0% for verbal communication but 20.9% (13 items out of 62) for written communication. He came close to be misdiagnosed as Wernicke's aphasia but, his language disorder was different from Wernicke's aphasia for naming, reading and spontaneous writing. He obtained a score of 21/30 on MMSE-K with written communication. Therefore, he was regarded as not having severe cognitive dysfunction for his age and educational status. He could not differentiate people's voices, music, and environmental sounds. Everything sounded like a disagreeable noise, a "buzzing", including pure tone signals. Standard pure tone threshold audiometry was conducted. The standard pure tone threshold audiometry showed normal findings (). Also brainstem auditory-evoked potentials (BAEP) exhibited normal bilateral latencies (). The visuo-cognitive and visuo-spatial functions were preserved. The results of evaluation studies are summarized in .\nHe could hear sounds but had difficulty in identifying words and environmental sounds such as: male and female voices, music, a baby crying, laughing sounds, an animal crying (cat, dog, cow, horse, pig, bird), instrumental sounds (piano, clocks, telephone ring), wind, a wave, and honk. Therefore, he was diagnosed as having generalized auditory agnosia with intracranial hemorrhage in the left basal ganglia and temporal lobe. He had speech therapy for variable sound differentiation and lip-reading with a listening program to foster communication skills. Six months after the recent stroke, a follow-up K-WAB and audiometry were performed and there was no significant interval improvement with the previous exam. Gradually he regained the ability to communicate and understand almost all the words used in daily life by trained lip-reading.