الفهرس 
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Abstract
Floppy infant is a broad symptomatic label given to a hypotonic child irrespective of etiology. The condition refers to an infant with generalized hypotonia presenting at birth or in early life. Floppiness is the most common reason of pediatric electrodiagnostic referral.
Floppiness is a chronic neurological problem demanding multidisciplinary approach for both diagnosis and management. History taking, clinical examination and investigations are mandatory to diagnose the cause of floppiness.
This study aimed at studying the clinical and electrophysiological findings in floppy infants and investigating the validity of quantitative EMG in the diagnosis of floppy infants.
The subjects enrolled in this study were 30 floppy infants presenting in their first two years of life, and 20 age-matched infants without any evidence of neuromuscular disorder (control group).
The etiological diagnosis of each floppy infant was based on history taking, clinical examination, serum CK level, nerve conduction studies and qualitative assessment of EMG pattern. Quantitative EMG was done for each infant but was not used in establishing the diagnosis.
Floppy infants were divided to three groups: CP (8 infants), neurogenic (19 infants) and myogenic (3 infants).
Generalized muscle atrophy was found in 12.5% of the CP group, 89.5% of the neurogenic group while none of the myogenic group showed muscle atrophy.
All infants in the CP and myogenic groups had grade 4 muscle power. In the neurogenic group, 15.8% had grade 1 muscle power, 42.1% had grade 2 and 42.1% had grade 3 muscle power.
In the CP group, one infant had unelicited deep tendon reflexes and the other 7 infants had exaggerated reflexes. All infants in the neurogenic group had unelicited reflexes while infants in the myogenic group had normally elicited reflexes.
Two infants in the myogenic group showed elevated serum level of CK and the other infants had normal level of CK.
As regard the sensory conduction studies, latency, amplitude and conduction velocity of the median and sural nerves did not vary significantly among the studied groups.
The latency and amplitude of mixed SEP elicited by stimulation of posterior tibial nerve, varied significantly among the studied groups. Latency in the CP group was prolonged and the amplitude was reduced compared to other groups.
The motor latency of femoral, posterior tibial and median nerves did not vary significantly among the studied groups. On the other hand the amplitude of the CMAP and the conduction velocity of those nerves were reduced in the neurogenic group compared to the CP and control groups.
In the CP group, the latency of the H-reflex was increased in comparison to the control group and the H/M ratio in the same group was higher than in other groups.
Abnormal rest potentials were found in 100% of the muscle in the neurogenic group and 66.7% in the myogenic group. There was no abnormal rest potentials recorded in the CP group.
All muscle in the CP group showed normal MUAPs on qualitative assessment. In the neurogenic group 26.3% of the studied muscles showed neuropathic MUAPs and 73.3% showed normal MUAPs. All muscle in the myogenic group showed myopathic MUAPs.
ANOVA revealed that all parameters of Multi-MUAP analysis varied significantly among the studied groups. The smallest amplitude, shortest duration and highest number of phases and turns were recorded in the myogenic group. The highest amplitude was recorded in the control group. The largest area, thickness and size index of the MUAP was found in the CP and control groups.
As regards the interference pattern, the highest number of turns and NSS were found in the myogenic group. The highest amplitude was found in the control group. The highest TAA, envelope and lowest activity were found in the neurogenic group.
The highest sensitivity of qualitative EMG was found in the CP and myogenic groups and the highest specificity in the neurogenic and myogenic groups.
The parameters of multi-MUAP analysis were more sensitive for myogenic group than the neurogenic group. The most sensitive IPA parameter for both myogenic and neurogenic groups were TAA, NSS and number of turns while the most specific parameters were number of turns and amplitude.
Discriminant analysis revealed that IPA parameters (namely the number of turns, TAA and amplitude) were more potent than multi-MUAP analysis parameters and qualitative EMG in classifying floppy infants.
It was concluded that quantitative EMG is more useful than qualitative EMG in the diagnosis of floppy infants. IPA has more diagnostic yield than multi-MUAP analysis in classifying floppy infants. Considering multi-MUAP analysis, size index and duration of MUAP were more informative than other MUAP parameters.