Variables:
(1) severity of injury to the nerve and to the supporting structures
(2) which nerve has been injured
(3) surgical repair following neurotmesis
(4) amount of damage caused by stretching
Sensory changes used to monitor recovery:
(1) pain
(2) touch
(3) Tinel's sign (distal tingling after percussion to the injured nerve)
Some average estimates for nerve recovery:
(1) radial nerve: 1.5 mm per day after axonotmesis +/- 0.1; 1.6 mm per day after repair +/- 0.2
(2) other nerves: 1.4 mm per day after axonotmesis +/- 0.1; 1.5 mm per day after repair +/- 0.2
(3) progression of Tinel sign after surgical repair: average 1.7 mm per day
The range for recovery is approximately 1-2 mm per day.
Steps in evaluation:
(1) Determine the level of sensory loss after injury and mark with indelible ink.
(2) Wait an interval of time. Since the detection methods are somewhat insensitive the interval should be in terms of weeks rather than days.
(3) Determine the level of sensory loss after the interval and mark with indelible ink.
(4) Measure the distance in mm between the 2 marks along the nerve path.
average regeneration in mm per day =
= (distance in mm) / (number of days)
The absence of recovery after several weeks suggests neurotmesis.
