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Auditory brain stem responses in infantile spasms
Insights
Infants with infantile spasms often have auditory brain stem evoked responses (ABRs) abnormalities, indicating brain stem involvement. This, along with psychomotor retardation, explains their poor response to sound.
Area of Science:
- Neuroscience
- Audiology
- Pediatrics
Background:
- Infantile spasms are associated with neurological dysfunction.
- Infants with infantile spasms often exhibit inattention to auditory stimuli.
- The precise level of auditory pathway lesion in these infants is not well understood.
Purpose of the Study:
- To investigate auditory brain stem evoked responses (ABRs) and behavioral thresholds in infants with infantile spasms.
- To determine the site of auditory pathway dysfunction in infants experiencing infantile spasms.
- To correlate auditory findings with psychomotor status.
Main Methods:
- Auditory brain stem evoked responses (ABRs) were measured, including thresholds, wave latencies, and interval latencies.
- Behavioral audiometric thresholds were assessed using conditioned-orientation-reflex (COR) audiometry.
- ABR data were compared to age-matched controls.
Main Results:
- Thirty percent of infants with infantile spasms displayed abnormal ABRs compared to controls.
- ABR abnormalities included wave disappearance, prolonged V-I interval, and absent responses, indicating brain stem dysfunction.
- Eighty-six percent of patients had elevated behavioral thresholds, suggesting cortical dysfunction due to psychomotor retardation, not peripheral hearing loss.
Conclusions:
- Brain stem involvement is a significant finding in infants with infantile spasms.
- Auditory inattention in these infants is primarily linked to psychomotor retardation and associated cortical dysfunction.
- ABR testing is crucial for identifying central auditory pathway lesions in infantile spasms.
Abstract:
Auditory brain stem evoked responses (ABRs) and behavioral thresholds were studied in 30 infants with infantile spasms to determine the level of the lesion causing their inattention to sound stimuli. ABR thresholds, peak latencies of waves I and V and the peak interval latency of wave V-I were measured; behavioral audiometric thresholds were determined through conditioned-orientation-reflex (COR) audiometry. Thirty per cent of the infants (9 cases) with infantile spasms showed ABR abnormalities with respect to age-matched controls. The ABR abnormalities were classified into partial disappearance of latter waves (5 cases), prolongation of the wave V-I peak interval (3 cases) and no response (1 case). These findings are clear evidence that brain stem involvement may occur in infantile spasms. Eighty-six per cent of the patients showed threshold elevation by behavioral audiometry which may reflect by cortical dysfunction inherent in psychomotor retardation, as there was no peripheral hearing loss. Our results reveal that brain stem involvement can occur in patients with infantile spasms and their poor responses to sound are due to psychomotor retardation.