AlS

[Florence007]

why do spastic paralysis in lower limbs and flaccid paralysis in upper limbs occur simultaneously in amyotrophic lateral sclerosis?

[Ikjot]

ALS is a combined UMN (upper motor neuron) and LMN (lower motor neuron) degenerative disease. With UMN lesions you have spastic paralysis due to loss of regulation and control over motor neurons, and with LMN lesions there is direct damage to motoneurons in the spinal cord leading to loss of function of the muscles innervated by those LMNs. Hope this helps. Cheers.

[Florence007]

Thanx, but why are UMN and LMN lesions combined together?

[imnalini]

usually affects cervical region so ant horn cell there are affected i.e lmn
below the lesion thye ant horn cell inervating lowerlimbs r intact but yhe umn supply is cutt off so umn lesion.