Journal of Neuroscience, Vol 15, 4109-4123, Copyright © 1995 by Society for Neuroscience
Monkey median nerve repaired by nerve graft or collagen nerve guide tube
SJ Archibald, J Shefner, C Krarup and RD Madison
Division of Neurosurgery, Duke University Medical Center, Durham, NC 27710, USA.
Nerve regeneration was followed in 15 median and 1 ulnar nerve of eight
Macaca fascicularis monkeys by serial electrophysiological assessments over
a period of three and a half years. Nerve gaps of 5 mm at the wrist were
bridged by collagen-based nerve guides, nerve autografts, or direct suture
repairs. Thenar muscle reinnervation occurred between 50 and 70 d for all
groups, indicating axonal elongation rates of approximately 1 mm/d. The
recovery rates of the compound muscle action potential (CMAP) and the
compound sensory action potential (CSAP) amplitudes were significantly
slower after direct suture repair compared to the other two procedures,
although the final levels of recovery were all comparable. Similar results
were achieved in one median and one ulnar nerve following nerve guide
repair of a 15 mm nerve gap. The functional reinnervation of Pacinian
corpuscles was detected in all cases following either nerve graft or nerve
guide repair, with similar amplitudes and latencies of the tactile evoked
CSAP for both types of repair. Histological analysis demonstrated a
significant increase in the number of myelinated axons in the median nerve
distal to the nerve lesions following both nerve graft and nerve guide
repairs compared to proximal and normal controls, with significant
reductions of fiber diameter and corresponding increases in g-ratio. The
return of a bimodal frequency distribution of myelinated axon fiber
diameter was confirmed by three-dimensional surface plots which illustrate
the frequency distribution of the relationship between fiber diameter and
g-ratio. These combined results demonstrate that nerve regeneration after
repair of a 5 mm nerve gap with a collagen nerve guide in the nonhuman
primate is similar to that after graft repair, and the final level of
physiological recovery for both repair procedures is comparable to direct
suture repair of the median nerve.
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