Step I Lesions caused by polio?

[CuriousGeorge2]

So, I just got a practice Q wrong regarding polio and what type of signs and sxs you would expect; I thought that you would see both UMN and LMN signs. The question was marked wrong and said it only affects LMNs; I just took at looks at the Gojan RR3 text and he says it affects UMNs and LMNs; who's correct here?

 

[CielloStelatto]

So, I just got a practice Q wrong regarding polio and what type of signs and sxs you would expect; I thought that you would see both UMN and LMN signs. The question was marked wrong and said it only affects LMNs; I just took at looks at the Gojan RR3 text and he says it affects UMNs and LMNs; who's correct here?

Classically polio virus infects the anterior horn cells (LMNs), and yes I've heard that it then spreads to infect the UMNs. However, the symptoms that I've seen associated with polio are the LMN symptoms - flaccid paralysis, hyporeflexia, plus atrophy in post-polio. Perhaps it has something to do with the LMNs getting hit first/stronger.

That, and according to google only about 8% of patients with post-polio syndrome get UMN symptoms.

 

[Dixe Reb]

Classically polio virus infects the anterior horn cells (LMNs), and yes I've heard that it then spreads to infect the UMNs. However, the symptoms that I've seen associated with polio are the LMN symptoms - flaccid paralysis, hyporeflexia, plus atrophy in post-polio. Perhaps it has something to do with the LMNs getting hit first/stronger.

That, and according to google only about 8% of patients with post-polio syndrome get UMN symptoms.

Do you have any idea WHY polio virus is unable (usually) to cross the synapse between LMN and UMN?