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  • Author or Editor: Hans Feirabend x
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Martijn J. A. Malessy, Sjoerd G. van Duinen, Hans K. P. Feirabend and Ralph T. W. M. Thomeer

Object. Proximal spinal nerve stumps were used as donor sites for grafts to repair brachial plexus traction lesions. The quality of the stumps was assessed histologically, and its correlation with the strength attained in the target muscle was studied.

Methods. Four histopathological parameters in frozen tissue sections of 31 C-5 or C-6 nerve stumps were examined by a neuropathologist. The total quantity of myelin was compared with normal values. Also, thick myelinated fibers, fibrosis, and misdirected axons were assessed. Stumps embedded in plastic were used in a morphometric study of myelinated fiber profiles. The fiber density, mean size, and size distribution in five donor stumps were determined; three normal C-5 spinal nerves obtained at autopsy served as controls. Finally, the relative area occupied by fiber profiles and interspace was computed. Linear regression was used as a multivariate analysis, adjusting the outcome of surgical repair for effects of age, interval between trauma and surgery, and graft length.

Histopathological examination showed that the total quantity of myelin in donor stumps used for biceps muscle reinnervation was considerably reduced. On morphometric examination the fiber density did not differ significantly between stumps obtained in patients and control stumps obtained at autopsy. However, a significant reduction of the area occupied by myelinated fibers was measured: from 46% in controls to 13% in patients (p < 0.0001). Likewise, a significant reduction was found in the mean fiber size: from 7.4 µm in controls to 3.7 µm in patients (p < 0.0001).

The relationship between the myelin quantity in the proximal stump and the grade of biceps muscle recovery was statistically significant (p = 0.02). From the 95% confidence interval it was concluded that the estimated effect of a mean increase of myelinated fibers by 25% almost equals an increase in recovery of one point on the Medical Research Council scale (grade range 0–5).

Conclusions. Both histopathological and morphometric examination showed a reduction of the quantity of myelin in C-5 or C-6 stumps used as donor sites for grafts. The amount of myelin is significantly correlated with biceps muscle function after nerve grafting. Because it is possible to assess the quantity of myelin by intraoperative examination of frozen sections, this correlation is potentially useful in the decision-making process of whether to use stumps for grafting or to use nerve transfer procedures to restore biceps muscle function.

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M. Sarah S. Bovenberg, M. Hannah Degeling, Godard C. W. de Ruiter, Hans K. P. Feirabend, Egbert A. J. F. Lakke and Carmen L. A. M. Vleggeert-Lankamp

Object

Accuracy of reinnervation is an important factor that determines outcome after nerve injury and repair. Type grouping—the clustering of muscle fibers of the same type after reinnervation—can be used to investigate the accuracy of reinnervation. In this study, the degree of type grouping after crush injury in rats was compared with the clustering of muscle fibers after autografting or single-lumen nerve grafting.

Methods

Twelve weeks after sciatic nerve crush injury in rats, clustering of Type I muscle fibers was analyzed in the target muscle with adenosine 5′-triphosphatase staining. In addition, the number of regenerated axons was determined in the nerve distal to the crush injury. Results were compared with that of the authors' previous study.

Results

Type grouping was more abundant after crush injury than after autograft or single-lumen nerve graft repair.

Conclusions

Crush injury leads to more clustered innervation of muscle fibers, probably because the Schwann cell basal lamina tubes are not interrupted as they are in autograft or artificial nerve graft repair. This finding adds to understanding the processes playing a role in nerve regeneration.

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Carmen L. A. M. Vleggeert-Lankamp, Jasper Wolfs, Ana Paula Pêgo, Rutgeris van den Berg, Hans Feirabend and Egbert Lakke

Object

In the present study the authors consider the influence of the porosity of synthetic nerve grafts on peripheral nerve regeneration.

Methods

Microporous (1–13 μm) and nonporous nerve grafts made of a copolymer of trimethylene carbonate and ε-caprolactone were tested in an animal model. Twelve weeks after surgery, nerve and muscle morphological and electrophysiological results of regenerated nerves that had grown through the synthetic nerve grafts were compared with autografted and untreated (control) sciatic nerves. Based on the observed changes in the number and diameter of the nerve fibers, the predicted values of the electrophysiological parameters were calculated.

Results

The values of the morphometric parameters of the peroneal nerves and the gastrocnemius and anterior tibial muscles were similar if not equal in the rats receiving synthetic nerve grafts. The refractory periods, however, were shorter in porous compared with nonporous grafted nerves, and thus were closer to control values.

Conclusions

A shorter refractory period enables the axon to follow the firing frequency of the neuron more effectively and allows a more adequate target organ stimulation. Therefore, porous are preferred over nonporous nerve grafts.