Which of the following is not seen after nerve transection?
Correct Answer: Neuroma in continuity
Description: Ans. is 'd' i.e., Neuroma in continuity Morphology after nerve transection* The morphologic hallmarks of axonal neuropathies produced by cutting a peripheral nerve, results in a prototypical pattern of injury described as Wallerian degeneration.* Portions of axons that are distal to the point of transsection are disconnected from the central neuron and degenerate.* Within a day of injury, the distal axons begin to fragment and the associated myelin sheaths unravel and disintegrate into spherical structures (myelin ovoids).* Macrophages are recruited and they participate in the removal of axonal and myelin debris.* Regeneration starts at the site of transsection with the formation of a growth cone and the outgrowth of new branches from the stump of the proximal axon.* Schwann cells and their associated basement membranes guide the sprouting axons, which grow at about 1 mm per day, toward their distal target.* Continuous pruning of the sprouting axons removes misguided branches.* The Schwann cells create new myelin sheaths around the regenerating axons, but these myelin internodes tend to be thinner and shorter than in the original ones.* The repair process is successful only if the two transected ends remain closely approximated.* A failure of the outgrowing axons to find their distal target can produce a "pseudotumor" termed traumatic neuroma-- a nonneoplastic haphazard whorled proliferation of axonal processes and associated Schwann cells that results in a painful nodule.Note* Neuroma in continuity is seen in Axonotemesis in which nerve is not transected. Complete transection (neurotmesis) produces neuroma (but not in continuity).
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