The Use of a Hypoallergenic Dermal Matrix for Wrapping in Peripheral Nerve Lesions Regeneration: Functional and Quantitative Morphological Analysis in an Experimental Animal Model.

INTRODUCTION: The aim of this research was to test, in an animal model, the nerve regeneration technique with a hypoallergenic acellular dermal matrix used to wrap the microsurgical neural suture. MATERIALS AND METHODS: Two groups of rats received the cut of limb right median nerves. The regeneration technique considers for both groups an end-to-end nerve suture. In the experimental group (A) was used also a wrapping protocol by a conduit of collagen matrix currently used in oral surgery. The animals underwent functional grasping tests (at 1, 3, 5, and 7 months) and a histological and quantitative analysis of distal nerve was performed at the end of experimental time. RESULT: After seven months, the grasping test reveals functional recovery in each tested animal; this improvement is more evident in Group A. The fibers appear well organized with restored myelin sheaths in both groups. Group A showed a great quantity of connective tissue surrounding the nerve. The quantitative morphology analysis in both groups shows a similar fibers density, fiber diameter, and myelin thickness. The differences between the groups in axon mean diameter are significant. In Group A M/d, D/d, and g-ratio is significantly higher compared to control group. CONCLUSIONS: Histological and functional assessments show a functional recovery of the injured nerve in the test groups, stressed by the results of the grasping tests and the meaningful increasing in fiber diameter and higher g-ratio. Moreover, a connective tissue cuff distinguishes the distal portion of the injured nerve. Considering the easy availability and handling of the material used in this study we can conclude that this experimental technique can be considered as a valid alternative to protect nerves in nerve wrap surgery.

Retalho tenar adipofascial reverso para cobertura do nervo mediano hipertrofiado em macrodactilia / The reverse adipofascial thenar flap for coverage of the hypertrophied median nerve in macrodactyly

A macrodactilia é uma anomalia congênita infrequente, caracterizada pelo crescimento desproporcional dos tecidos ósseo, gorduroso, nervoso, vascular e dérmico nos dedos das mãos ou dos pés. Existem muitas teorias sobre a sua etiopatogenia, sendo a mais aceita a hiperestimulação por fatores de crescimento enviados através dos nervos. Foram descritos alguns casos associados com a síndrome do túnel do carpo. Apresenta-se um caso clínico de síndrome do túnel do carpo por hipertrofia do nervo mediano, evidenciando um aumento de conteúdo dentro do retináculo flexor, o qual foi tratado cirurgicamente com sucesso pela realização de uma retinaculotomia do ligamento anular do carpo junto a um retalho de transposição tenar adipofascial reverso da região tenariana hipertrofiada visando à cobertura do nervo mediano na região do punho.

Macrodactyly is a rare congenital anomaly characterized by the disproportionate growth of bone, fat, nervous, vascular, and dermal tissue in the digits . There are many different theories about its etiopathogenesis, the most accepted being a hyperstimulation by growth factors conducted through nerves. A few cases have been described in conjunction with carpal tunnel syndrome. Here, a clinical case of carpal tunnel syndrome due to hypertrophy of the median nerve is presented, showing an increase of content within the flexor retinaculum. Successful surgical treatment was accomplished by conducting a retinaculotomy of the anterior annular ligament along with a reverse transposition adipofascial flap of the hypertrophied thenar region for coverage of the median nerve at the wrist.