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So there is a classification for nerve injuries.

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Uh, initially said, uh, classified them on, on a model

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of mild, uh, moderate or uh, severe.

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So neuropraxia is the mildest type of, uh, nerve injury.

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Axon noesis is when there is an injury to the axon

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and neuro missis is complete severance of the nerve.

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Sutherlin, uh, later on, uh,

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classified the nerve injuries in five grades.

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So grade one corresponds to the heist form neuropraxia

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and grade five to the severance of the nerve neuro messes.

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And in between we have grade two, three,

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and four, which is an injury, uh, to the axon.

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But in grade two we have an injury to the axon,

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but no injury to the endoneurium.

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Grade three, an injury to the innium

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and grade four, an injury to the perineurium.

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So the injury to the perineurium

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surrounding the fascicle will lead eventually

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to a aroma in continuity.

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So usually grade four and five are managed surgically.

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So in neuropraxia it's the mildest type of injury.

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It's a, for example, a mild case of carpal tunnel syndrome.

1:18

It's an injury to the myelin sheath around the axon.

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The axon is intact and usually the muscles are normal.

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May be slightly hyperintense on, uh,

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the T two weighted images

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and the patients usually present for sensory dysfunction.

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The prognosis is excellent with full recovery expected

1:40

in axon misses by definition, there is an injury to the axon

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and the epineurium is intact.

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So because the epineurium is intact,

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axonal regeneration is possible usually about

1:54

one millimeter per day.

1:56

But if there is an injury to the perineurium

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around the fassal, then it leads to fassal discontinuity

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and the originating axon are, um, misdirected

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and become entangled with fibrosis.

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And this is what leads to a neuroma in continuity.

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A grade four. So one MRI,

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we'll see an increase in the t single

2:20

of the nerve initially.

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And then with progression in the grading,

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we'll see enlargement and loss of the physical appearance,

2:28

and we will see denervation changes in the muscles

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innervated by that nerve.

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In neuro missis, there is complete severance of the nerve.

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So by definition, the epi is injured.

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It's a grade five, and this leads to a, a form formation

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of the bol neuroma like we see, uh, in amputations

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and eventually severe denervation changes in the muscles.

2:53

So this is an example of a patient who had a bullet injury

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to the thigh, and you can see the, uh, trajectory

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of the bullet through the sciatic nerve.

3:02

I.