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Evoked potentials in infant brainstem syndrome associated with Arnold-Chiari malformation
A B Barnet1, I P Weiss, C Shaer
1George Washington University School of Medicine and Health Sciences, Washington, DC.
Insights
Median nerve somatosensory evoked potentials (SEPs) show promise for assessing brainstem dysfunction in infants with Arnold-Chiari malformation and myelomeningocele, even when other tests are inconclusive.
Area of Science:
- Neuroscience
- Pediatric Neurology
- Clinical Electrophysiology
Background:
- Infants with myelomeningocele and Arnold-Chiari malformation often exhibit brainstem dysfunction.
- Assessing brainstem function in this population is crucial for diagnosis and management.
- Existing electrophysiological methods may have limitations in sensitivity.
Purpose of the Study:
- To evaluate the utility of brainstem auditory evoked potentials (BAEPs) and median nerve somatosensory evoked potentials (SEPs) in detecting brainstem dysfunction.
- To determine if these evoked potentials can differentiate infants with and without infant brainstem syndrome (IBS).
Main Methods:
- Studied 16 infants under one year of age with myelomeningocele and Arnold-Chiari malformation.
- Recorded BAEPs and median nerve SEPs.
- Analyzed I-V interwave latency (brainstem transmission time, BSTT) and SEP components (e.g., N20).
Main Results:
- Abnormally prolonged BSTT was observed in 11 infants but did not distinguish between those with and without IBS.
- The N20 component of median nerve SEPs was abnormal (absent, low amplitude, or prolonged latency) in all six infants with clinical signs of brainstem dysfunction and four without.
- Median nerve SEPs showed a significant difference between infants with and without IBS.
Conclusions:
- Median nerve SEPs appear to be a valuable tool for assessing brainstem function in infants with Arnold-Chiari malformation.
- BAEPs, specifically BSTT, were less effective in differentiating subgroups within this cohort.
- Further research may confirm the role of median nerve SEPs in managing pediatric neurological conditions.
Abstract:
This study evaluated the contribution of brainstem auditory evoked potentials (BAEPs) and median nerve somatosensory evoked potentials (SEPs) to the assessment of brainstem dysfunction in infants with myelomeningocele and Arnold-Chiari malformation. 16 infants under one year of age were studied. Six had infant brainstem syndrome (IBS). 11 had abnormally prolonged I-V interwave latency (brainstem transmission time, BSTT); BSTT did not differentiate those patients with and without IBS. The cortical 'N20' component of the median-nerve SEPs was absent or had low amplitude and prolonged latency in all six patients with clinical signs of brainstem dysfunction and in four without. Median-nerve SEPs were normal in the patients without IBS. There was a significant difference between patients with and without IBS. Median-nerve SEPs may be a helpful measure of brainstem function in infants with Arnold-Chiari malformation.