Effect of prematurity and intrauterine growth restriction on H-reflex recovery cycle in 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.
Bhatia
B D
BD
Department of Pediatrics, Unit of Neonatology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India. baldev bhatia@rediffmail.com
Kumar
Ayan
A
Deepshikha
Prakash
Udai
U
D004558:Electric Stimulation; D004594:Electrophysiology; D005317:Fetal Growth Retardation / Q000503:physiopathology*; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*