Why are deficits of anterior cord syndrome more severe in lower limb?

[loveoforganic]

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Is this a function of the anterior spinal artery being obstructed, and there being less radicular supply to lower cord? Or is this a function of most radicular supply being at T-spine segments and below, leaving the upper limbs mostly unaffected in a major radicular artery (e.g. adamkiewicz) obstruction? Or both?

Thanks in advance!

 

[OveractiveBrain]

Is this a function of the anterior spinal artery being obstructed, and there being less radicular supply to lower cord? Or is this a function of most radicular supply being at T-spine segments and below, leaving the upper limbs mostly unaffected in a major radicular artery (e.g. adamkiewicz) obstruction? Or both?

Thanks in advance!

I think you are taking a --usual-- and trying to justify it as an --absolute--. Let me explain:

Anterior cord syndrome doesn't have to be more prominent in the lower extremities. IF it is a product of obstruction of the artery of Adamkeiwickzs (whatever its name is), say, from a AAA, then the arterial supply to the T-spine and below is compromised, so the legs WILL be coomprimised. Its a product of arterial flow (anterior spinal arteries are not irrigated by the artery of adam). On the other hand, you can get anterior cord syndrome from hyperextension of the neck, especially in old people, that leads to symptoms worse in the ARMS. This ins't suprising, because you can shear the anterior spinal arteries supplying that area, or just the force trauma and edema can disrupt the cord at the site of the lesion.

Even still, you have to remember that all motor and sensory fibers run through the cord. So if you have a lesion at the neck, the legs can be affected. If you have a lesion at the lumbar region, the legs can be affected. So, if you can be affected in the legs regardless of where the injury, -- lower extremities are more common --Its been a while since neuroanatomy, so, someone closer to the content might be able to answer better.

 

[gravitywave]

you're overthinking it

best place for an anterior infarct is in the watershed area between adamkiewicz and anterior artery, around T4-8 or so. upper limb roots are already long gone by then (C5-T1). but you still have glia looking after the UMN axons running down to lumbar/sacral plexus: if they die in the watershed area, you lose those axons and have UMN syndrome/spinothalamic problems from that point down.

 

[loveoforganic]

Thank y'all, makes sense!