The effects of cortical ischemic stroke on auditory processing in humans as indexed by transient brain responses.

Objective: To investigate the effects of cortical ischemic stroke and aphasic symptoms on auditory processing abilities in humans as indicated by the transient brain response, a recently documented cortical deflection which has been shown to accurately predict behavioral sound detection.

Methods: Using speech and sinusoidal stimuli in the active (attend) and the passive (ignore) recording condition, cortical activity of ten aphasic stroke patients and ten control subjects was recorded with whole-head MEG and behavioral measurements.

Results: Stroke patients exhibited significantly diminished neuromagnetic transient responses for both sinusoidal and speech stimulation when compared to the control subjects. The attention-related increase of response amplitude was slightly more pronounced in the control subjects than in the stroke patients but this difference did not reach statistical significance.

Conclusions: Left-hemispheric ischemic stroke impairs the processing of sinusoidal and speech sounds. This deficit seems to depend on the severity and location of stroke.

Significance: Directly observable, non-invasive brain measures can be used in assessing the effects of stroke which are related to the behavioral symptoms patients manifest.