FA clarification

[kdirnfueu]

FA says that with median nerve lesions you get "Loss of sensation over thenar eminence and dorsal and palmar aspects of lateral 3.5 fingers with proximal lesion"

Zanki interprets this as losing sensation over thenar eminence in both distal/proximal median nerve lesions and losing sensation over the rest of the median nerve distribution in the lateral hand with a proximal lesion only.

However, I'm pretty sure FA meant that with a proximal lesion you lose sensation to all three (since in a distal lesion you can spare sensation to the palmar cutaneous branch over the thenar eminence)

Am I interpreting this correctly?


Oh and while we're at it, in the section where it talks about the hand deformities (ulnar claw/OK gesture + Pope's blessing/median claw), why do they differentiate between distal and proximal? Wouldn't all median/ulnar lesions regardless of how distal/proximal lead to lumbrical paralysis --> clawing of fingers? Am I wrong to assume that "ulnar claw" and "OK gesture" are the same things but one's at rest and one's when trying to make a fist? Are they juts trying to make the point that distal lesions have more severe clawing?

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[Greyhame]

FA says that with median nerve lesions you get "Loss of sensation over thenar eminence and dorsal and palmar aspects of lateral 3.5 fingers with proximal lesion"

Zanki interprets this as losing sensation over thenar eminence in both distal/proximal median nerve lesions and losing sensation over the rest of the median nerve distribution in the lateral hand with a proximal lesion only.

However, I'm pretty sure FA meant that with a proximal lesion you lose sensation to all three (since in a distal lesion you can spare sensation to the palmar cutaneous branch over the thenar eminence)

Am I interpreting this correctly?


Oh and while we're at it, in the section where it talks about the hand deformities (ulnar claw/OK gesture + Pope's blessing/median claw), why do they differentiate between distal and proximal? Wouldn't all median/ulnar lesions regardless of how distal/proximal lead to lumbrical paralysis --> clawing of fingers? Am I wrong to assume that "ulnar claw" and "OK gesture" are the same things but one's at rest and one's when trying to make a fist? Are they juts trying to make the point that distal lesions have more severe clawing?

With a distal lesion (eg Carpal Tunnel Syndrome) the sensation over thenar is preserved. And with a proximal lesion, as you mentioned, you lose sensation to all three.
Clawing occurs at rest. And with distal lesions due to loss of innervation to lumbricals. Lumbricals flex your metacarpophalangeal joints and extend the interphalangeal joints. Isolated loss of lumbrical function (in distal median/ulnar lesions) results in loss of these two movements and clawing.
So while 'ulnar claw' and "Pope's blessing" appear same, it is important to know if the deformity is present at rest (Ulnar Claw) or when trying to make a fist (Pope's blessing/Hand of benediction). The former is due to a DISTAL ulnar nerve injury while the later is due to a PROXIMAL median nerve injury.

'Okay gesture' refers to an inability to close the medial fingers into a fist and is due to a proximal ulnar nerve injury.

 

[OurDeadGrass]

With a distal lesion (eg Carpal Tunnel Syndrome) the sensation over thenar is preserved. And with a proximal lesion, as you mentioned, you lose sensation to all three.
Clawing occurs at rest. And with distal lesions due to loss of innervation to lumbricals. Lumbricals flex your metacarpophalangeal joints and extend the interphalangeal joints. Isolated loss of lumbrical function (in distal median/ulnar lesions) results in loss of these two movements and clawing.
So while 'ulnar claw' and "Pope's blessing" appear same, it is important to know if the deformity is present at rest (Ulnar Claw) or when trying to make a fist (Pope's blessing/Hand of benediction). The former is due to a DISTAL ulnar nerve injury while the later is due to a PROXIMAL median nerve injury.

'Okay gesture' refers to an inability to close the medial fingers into a fist and is due to a proximal ulnar nerve injury.

Is ulnar claw only seen in distal ulnar lesion or can it be seen in proximal ulnar lesion as well?

 

[kdirnfueu]

Is ulnar claw only seen in distal ulnar lesion or can it be seen in proximal ulnar lesion as well?

lol that's actulaly what I was getting at with my original post, because either distal or proximal you get lumbrical paralysis, with the only difference being the distal claw would be more pronounced (or maybe that IS the point? with proximal lesions you need to make a fist to see the problem?)

 

[Greyhame]

Clawing occurs due to isolated loss of lumbrical function. Intact extensors extend metacarpophalangeal joints and intact flexor muscles of forearm flex the interphalangeal joints==>claw.
With proximal lesions, extensor/flexor muscles of forearm go too. So instead of a claw you'll get loss of flexion of fingers (4th and 5th) in case of a proximal ulnar lesion. Which can be seen on making a fist, like kdirnfueu mentioned.

A proximal radial lesion manifests as wrist drop, among other things.