Effect of prematurity and intrauterine growth restriction on H-reflex recovery cycle in neonates
Related Experiment Video
Updated: Jun 9, 2026
Neurodevelopmental Reflex Testing in Neonatal Rat Pups
Published on: April 24, 2017
B D Bhatia1, Ayan Kumar, Deepshikha
1Department of Pediatrics, Unit of Neonatology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India. baldev bhatia@rediffmail.com
Insights
Preterm infants show delayed spinal cord synapse function compared to full-term babies, impacting H-reflex recovery. This suggests potential neurotransmitter depletion in preterm neonates, affecting neural development.
Area of Science:
- Neuroscience
- Developmental Biology
- Pediatrics
Background:
- Spinal cord synapse development is crucial for motor function.
- Prematurity and intrauterine growth restriction can impact neurological development.
- The H-reflex is a valuable tool for assessing spinal cord reflex pathways.
Purpose of the Study:
- To evaluate the impact of prematurity and intrauterine growth restriction on spinal cord synapses.
- To compare H-reflex parameters in full-term appropriate for gestational age (FT AGA), full-term intrauterine growth restricted (FT IUGR), and preterm appropriate for gestational age (PT AGA) neonates.
Main Methods:
- Investigated 33 neonates: 14 FT AGA, 10 FT IUGR, and 9 PT AGA.
- Recorded H-reflex parameters including Hmax, HRL, H/M ratio, HRCV, and HRRC.
- Utilized double stimuli technique to assess H-reflex recovery cycle in the soleus muscle.
Main Results:
- H-reflex recovery was significantly lower in PT AGA neonates compared to FT AGA and FT IUGR groups.
- No significant differences in H-reflex parameters were found between FT AGA and FT IUGR groups.
- H-reflex latency (HRL) and H-reflex conduction velocity (HRCV) were significantly affected in the PT AGA group.
Conclusions:
- Delayed H-reflex recovery in preterm infants may indicate prolonged neurotransmitter delay at Ia terminals.
- This delay could stem from reduced neurotransmitter stores in synaptic vesicles within the preterm spinal cord.
- Findings highlight potential synaptic functional deficits in preterm neonates.
Objective:
The purpose of this work was to assess the effects of prematurity and intrauterine growth restriction on spinal cord synapses using H-reflex.
Methods:
33 babies were investigated at birth. 14 were full term appropriate for gestational age (FT AGA), 10 were full term intrauterine growth restricted (FT IUGR) and 9 were preterm appropriate for gestational age (PT AGA). The maximum amplitude of H-reflex (Hmax), H-reflex latency (HRL), H/M ratio, H-reflex conduction velocity (HRCV), and H-reflex response to double stimuli (conditioning and test) for H-reflex recovery cycle (HRRC) were recorded in right lower limb (soleus muscle) in all the three groups.
Results:
Percentage recovery values of H-reflex were significantly higher in FT AGA and FT IUGR babies compared to PT AGA neonates for most of inter-stimulus intervals. No significant differences were observed in H-reflex parameters between FT AGA and FT IUGR groups, but HRL and HRCV were significantly affected in PT AGA group.
Conclusions:
Delayed H-reflex recovery in preterms may be due to a prolonged state of neurotransmitter delay in Ia terminals following initial activation by the conditioning stimuli. The cause of such prolonged depletion of neurotransmitters could be attributed to a poor neurotransmitter store in synaptic vesicles of spinal cord in preterm neonates.
