Step I Internal Capsule Lesion

[kwhippy]

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If there is a lesion in the internal capsule, would it cause a motor ans sensory deficit?

I was thinking that it would cause both but i am not sure.

 

[ButterButter]

I was literally just reading about this from my World notes. The anterior limb has a lot of stuff going on, which I will steer away from here, but the posterior limb has both motor and sensory components. The anterior 2/3 of the posterior limb of the internal capsule mainly consists of corticospinal tract motor fibers (descending from the cortex), while the posterior 1/3 of the posterior limb contains ascending sensory fibers from the thalamocortical tract. Although very small lesions to the posterior limb may cause contralateral pure sensory deficits, most lesions result in pure motor or combined sensorimotor deficits.

Hope this helps.

 

[Phloston]

Typically pure sensory is thalamus and pure motor is posterior limb of internal capsule.

 

[kwhippy]

I was literally just reading about this from my World notes. The anterior limb has a lot of stuff going on, which I will steer away from here, but the posterior limb has both motor and sensory components. The anterior 2/3 of the posterior limb of the internal capsule mainly consists of corticospinal tract motor fibers (descending from the cortex), while the posterior 1/3 of the posterior limb contains ascending sensory fibers from the thalamocortical tract. Although very small lesions to the posterior limb may cause contralateral pure sensory deficits, most lesions result in pure motor or combined sensorimotor deficits.

Hope this helps.

Thanks alot 🙂

So just to see if i understood it correctly, there could be a sensory deficit as well but most lesions will cause contralateral hemiplegia. Right?

 

[kwhippy]

Typically pure sensory is thalamus and pure motor is posterior limb of internal capsule.

Thanks!! That basically sums it up! 😀

 

[slz1900]

Typically pure sensory is thalamus and pure motor is posterior limb of internal capsule.

Do you know the reason for this? Seems counterintuitive since there are thalamocortical fibers in the posterior limb (right?)

 

[Phloston]

Do you know the reason for this? Seems counterintuitive since there are thalamocortical fibers in the posterior limb (right?)

Was more just something I memorized from FA way back when. Not sure where you are in terms of med, but one thing I learned going through med school was that nothing can be pigeon holed, ever. That is, I wouldn't be surprised if you could get different types of outcomes with strokes in those lesions for the reasons you've mentioned, but perhaps those are the more frequent ones and hence most often tested that way.