Following traumatic peripheral nerve transection, regrowth usually occurs at which of the following rates?
Transection of a peripheral nerve results in hemorrhage and in retraction of the severed nerve ends. Almost immediately, degeneration of the axon distal to the injury begins. Degeneration also occurs in the proximal fragment back to the fist node of Ranvier. Phagocytosis of the degenerated axonal fragments leaves a neurilemmal sheath with empty cylindrical spaces where the axons were. Several days following the injury, axons from the proximal fragment begin to regrow. If they make contact with the distal neurilemmal sheath, regrowth occurs at about the rate of 1 mm per day. However, if associated trauma, fracture, infection, or separation of neurilemmal sheath ends precludes contact between axons, growth is haphazard and a traumatic neuroma is formed. When neural transection is associated with widespread soft tissue damage and hemorrhage (with increased probability of infection), many surgeons choose to delay re-approximation of the severed nerve end for 3-4 week.
0.1 mm per day
1 mm per day
5 mm per day
1 cm per day
Trauma