Electrophysiological studies in children with paralytic poliomyelitis.

Ten healthy children (Group I), twenty children with acute spinal poliomyelitis (Group II and III) and twenty children of post-polio residual paralysis (Group IV) between the age group of 9 months to 4 years were the study subjects. The motor nerve conduction velocity (MNCV), standardized distal motor latency (SDML) and motor latency (M-RL) were similar in all the groups studied No H-reflex could be elicited in children with acute spinal poliomyelitis seen within one week of onset of paralysis (Group II). The H-max from 4-6 week group (III) improved with time in 9-12 month (Group IV) but did not attain the control (Group I) value. The H-reflex latency (H-RL) which was prolonged in Group III children returned back to normal value in children with residual paralysis (Group IV). The M-max which was significantly reduced in Group II children further decreased in Group III children before showing a significant rise in children with residual paralysis (Group IV). The M-max showed a significant correlation to duration of paralysis during the first week of onset of the disease process and with the muscle power assessed clinically in children with residual paralysis (Group IV). The H/M ratio of children with acute paralysis (Group III) was similar to control while that of residual paralysis was significantly lower in comparison to controls. However, the corrected H/M ratio of children with acute paralysis (Group III) and residual paralysis (Group IV) was significantly lower than the controls. There was significant increase in corrected H/M ratio in group IV children compared to group III.