mesh
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why there is reversal of cutaneous reflex(babinski reflex, instead of flexor respose there is extensor respose) in case of UMN lesion. while the other cutaneous reflexes are lost.
plz explain thanks.
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| Siam
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Hmmm...what I got from "First AID" is UMN=everything up (tone,DTR,toes) but for cutaneous reflex...I don't know either
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| ssrpk
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cutaneous reflexes are lost in case of UMN lesion
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| mesh
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yeah u r right but y there is an extensor response.if the reflex is lost then there should nt be ne response.( in this particular case we can say that it is altered nt lost).
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| ssrpk
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well it's just the way the builtin inherent neural circuitry is made, which is quite evident in infants in whom the myelination process of the corticospinal spinal tracts are ongoing....therefore they elicit babinski's sign uptill one yr of life ,which becomes -ve thereafter for the rest of the life untill and unless UMN lesion takes place (back to the stone age)
more importantly the details are'nt very well known! 
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| alphahmed
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Well... I will try to guess...
it is because of two elements for the Babinski's sign one is through UMN reflex which is normally dominent but when there is UMN leision it weakens leting the LMN reflex to occur...
Am I right?
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| mesh
Forum Guru
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it is nt only with babinski sign it is with all reflexes,that there r two elements one is UMN and other is LMN.
UMN has downregulatory control over the reflexes...so when there is UMN lesion down regulation is lost and it leads to hyperreflexia....
and in case of LMN lesion the reflexes are lost ....
but here in babinski there is nt hyperreflexia, reflex is present but the response is opposite....
I agree with ssrpk that details are nt very well known....
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