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Biomedical subjects

M L Pinheiro

Publications and source records attributed to M L Pinheiro.

14 recordsLinked to original sources

P300 results in patients with lesions of the auditory areas of the cerebrum.

Auditory P300 event-related potentials were obtained at C3 and C4 recording sites from 20 patients with cerebral lesions that affected auditory areas of the brain. The patient group was matched for age and hearing sensitivity to a control group of 20 subjects. There were significant differences between the two groups for both latency and amplitude of the P300. Eight patients demonstrated an absent P300 for at least one recording condition while all subjects in the control group had readable P300s in all recording conditions. A subset of patients with lesions limited to one hemisphere showed no laterality effects for amplitude or latency of the P300 for the ear or electrode that was either ipsilateral or contralateral to the lesion. In comparison to the P2 evoked potential, the P3 was more sensitive to neurologic lesions.

Adolescent

Duration pattern recognition in normal subjects and patients with cerebral and cochlear lesions.

Three groups of subjects were tested on a duration pattern recognition task. The groups included normal subjects, subjects with cochlear hearing loss, and subjects with lesions involving but not limited to the auditory areas of the cerebrum. Results indicated no significant difference in pattern recognition between the normal subjects and subjects with cochlear hearing loss. However, the subjects with cerebral lesions performed significantly more poorly than either the normal subjects or those with cochlear hearing loss. In comparing pattern recognition performance for the ears ipsilateral and contralateral to the lesioned hemispheres no differences were noted. Rather, when a central lesion was present, both ears generally yielded abnormal scores.

Adult

Frequency patterns in cochlear, brainstem, and cerebral lesions.

Three groups of patients with different pathologies (cerebral, brainstem, and cochlear lesions) were tested and compared for performance on frequency patterns. Results indicated that the frequency pattern test was highly sensitive to cerebral lesions (83%), but not as sensitive to brainstem lesions (45%). There was very little overlap between results of subjects with cochlear hearing loss and those with cerebral lesions. The specificity of frequency patterns for detecting cerebral lesions (the number of true negative results divided by the number of cochlear subjects) was 88.2%.

Adolescent

Auditory dysfunction following a gunshot wound of the pons.

A patient with a gunshot wound penetrating the right side of the brainstem at the level of the pons was given a test battery to evaluate peripheral hearing function and central auditory processing abilities. A month later, the left ear had a loss of sensitivity for high frequency tones, decreased speech discrimination, and excess tone decay. Two years later these deficits had resolved. However, a central auditory impairment remained, affecting the right ear score on Binaural Fusion and left ear scores on dichotic tasks and tonal pattern sequences.

Adolescent

Audiological manifestations in "split brain" patients.

Traditional peripheral hearing tests (pure-tone thresholds, speech reception thresholds, and speech discrimination) and selected "central" hearing tests were administered to three commissurotomized patients. One patient was tested both pre-and postoperatively, whereas the remaining two were tested only postsurgery. Results indicated that commissurotomy had no apparent effects on performance on the peripheral tests. However, various tests in the central battery showed definite abnormal results. Most significant were the results from dichotically presented speech stimuli which repeatedly showed total absence of responses for stimuli presented to the left ear. Additional experimentation indicated this monaural deficit could be overcome by reducing the intensity level of right ear stimuli. Results for low-redundancy, monotically presented speech stimuli also indicated a left ear deficit; however, these results were not as consistent as the dichotic data.

Adolescent