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Electrically elicited blink reflex in normal neonates
Insights
Neonatal blink reflex studies show early component R1 is present in most infants, but late component R2 is less common. This suggests reduced reflex excitability in neonates, primarily affecting interneurons.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Clinical Neurology
Background:
- The blink reflex is a crucial neurological test.
- Understanding neonatal reflex development is vital for assessing neurological function.
Purpose of the Study:
- To investigate the characteristics of the electrically elicited blink reflex in full-term neonates.
- To compare neonatal blink reflex components (R1 and R2) with adult responses.
Main Methods:
- Electrically elicited blink reflex testing was performed on 30 full-term neonates.
- Latency and elicitation of early (R1) and late (R2) components were recorded and analyzed.
Main Results:
- Early component R1 was elicited in most neonates (27/30) with a mean latency of 12.1 ms.
- Late component R2 was elicited in fewer neonates (20/30), primarily ipsilaterally.
- Neonatal R1 latency was significantly longer than in adults, despite a shorter reflex arc.
Conclusions:
- Neonates exhibit distinct blink reflex characteristics compared to adults.
- The reduced excitability of the polysynaptic R2 component suggests immaturity at the interneuron level in neonates.
Abstract:
The electrically elicited blink reflex was tested in 30 full-term neonates. Of the two distinctly separate responses, early component R1 and late component R2, R1 was recorded in all but three infants. Its latency, 12.1+/-1.0 msec (mean+/-SD), was significantly greater than that in adults (10.6+/-0.8 msec) despite a considerably shorter length of the reflex arc in infants. Unlike the response in adults, R2 was elicited in only 20 of 30 infants, mostly on the side ipsilateral to the stimulus. The reduction of reflex excitability of R2 in neonates must occur primarily at the level of interneurons since oligosynaptic R1 was elicited with ease whereas polysynaptic R2 was not.