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Double disconnection effects resulting from infiltrating tumors.
J J Sidtis1, A E Sadler, R D Nass
1Department of Neurology, Memorial Sloan-Kettering Cancer Center.
Neuropsychologia
|January 1, 1989
Summary
Patients with left hemisphere damage may show impaired hearing in the left ear, a phenomenon termed "paradoxical extinction." This study suggests renaming it "callosal extinction" due to corpus callosum involvement.
Area of Science:
- Neuroscience
- Neurology
- Auditory Processing
Background:
- Left hemisphere lesions near the lateral ventricles can impair left ear responses in dichotic listening tests.
- This auditory deficit, ipsilateral to the lesion, is termed 'paradoxical' due to its unexpected presentation.
Observation:
- Two patients with corpus callosum tumors exhibited this 'paradoxical' left ear deficit.
- These patients also showed right ear extinction on a complex pitch discrimination task, indicating right hemisphere involvement.
Findings:
- The manifestation of auditory extinction (left or right ear) depends on the specific cognitive task employed.
- The term 'paradoxical extinction' is imprecise given the task-dependent nature of the deficit.
Implications:
- The findings suggest that callosal pathways are critical for integrating auditory information from both hemispheres.
- Renaming the phenomenon 'callosal extinction' more accurately reflects the underlying neuroanatomical and functional mechanisms.
- This revised terminology aids in understanding interhemispheric communication and lesion effects in auditory processing.