Auditory discrimination after left-hemisphere stroke: a mismatch negativity follow-up study.
OBJECTIVE
We sought to determine the recovery of cortical auditory discrimination in aphasic, left-hemisphere-stroke patients by using an electrophysiological response called mismatch negativity (MMN) and speech-comprehension tests.


METHODS
MMN in 8 left-hemisphere stroke patients was recorded in response to duration and frequency changes in a repetitive, harmonically rich tone 4 and 10 days and again 3 and 6 months after their first unilateral stroke. Eight age-matched, healthy persons served as control subjects.


RESULTS
At 4 days after stroke onset, patients' sound discrimination was impaired in their left hemisphere, as suggested by attenuated MMNs, especially to right-ear stimuli. At 3 months after stroke, however, MMN to the right-ear duration change had significantly increased and was of normal size. A significant change for the frequency MMN was found for left-ear stimuli between 3 and 6 months after stroke. During the follow-up period, progressive improvement in speech-comprehension tests was also observed. Furthermore, there was a significant correlation between the change in the duration MMN amplitude and the Boston Diagnostic Aphasia Examination speech-comprehension test from 10 days to 3 months after stroke.


CONCLUSIONS
These results suggest that the MMN can be used as an index of the recovery of auditory discrimination.
Ilvonen
Titta-Maria
TM
Cognitive Brain Research Unit, Department of Psychology, University of Helsinki, Finland.
Kujala
Teija
T
Kiesiläinen
Anita
A
Salonen
Oili
O
Kozou
Hesham
H
Pekkonen
Eero
E
Roine
Risto O
RO
Kaste
Markku
M
Näätänen
Risto
R
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001037:Aphasia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D004594:Electrophysiology; D005071:Evoked Potentials; D005260:Female; D005500:Follow-Up Studies; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011930:Reaction Time; D020127:Recovery of Function; D012016:Reference Values; D013063:Speech Discrimination Tests / Q000379:methods; D020521:Stroke / Q000150:complications / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed