Engineered Nerve-Regeneration in Disruptive Brachial Plexus Lesions: A Novel Surgical Approach
Antonio Merolli, MD, FBSE1; Maria Lucia Manunta, VMD2; Claudio Proietti, MSc3; Eraldo Sanna Passino, VMD2
1Rutgers University Piscataway, NJ, 2Universita' di Sassari, Sassari, Italy, 3Universita' Cattolica, Rome, Italy
Introduction: The partial or total disruption of brachial plexus (BP) due to an external mechanical agent (fractured bone ends; penetrating wounds; schnaprels and gun-shot wounds: etc) is a severe occurrence. In less disruptive injuries, when a single or a limited number of nerve bundles are involved, standard techniques of peripheral nerve surgery can be applied, like: direct repair; nerve autograft; nerve allograft; artificial nerve-guides (conduits). The latter have been introduced in BP surgery in children and in adults as an adjunct to neurorrhaphy. However, when a large or complete disruption of the BP structure occurs, the surgeon may abstene from an immediate treatment, waiting to assess the final deficit and, then, proposing reconstructive surgery (nerve and/or tendon transfers, for example).
Materials and Methods: We designed and implanted a device (called NeuroBox) aimed at protecting the whole brachial plexus (as it was a single peripheral nerve). We tested three different animal models, namely the Wistar Rat, the New Zealand White Rabbit and the Sardinian Sheep; the latter was selected as a translational model. Twelve sardinian adult female ewes were used (2.5-5 years old, body weight 39.5 ± 7.7 Kg). The device was designed and refined by accessing the BP in the first four animals. Then, eight sheep were implanted after a lesion was produced, which consisted of the transection of the left BP fibres at the level of the cords, leaving only those directed to the ulnar nerve.
Results: Successive refinements in the design resulted in a double-halved device with a trapezoidal shape. After surgery, all the animals were unable to move their left anterior limb. Then a gradual clinical recovery occurred and, at two months post-op, an initial functional recovery was observed. Five animals still have the device in place to assess long-term (12 months) efficacy of the treatment. Retrievals performed at 15, 30 and 60 days (one animal each) showed the phases of nerve regeneration (15 days, blood clot; 30 days, initial fibrin phase; 60 days, late fibrin phase).
Conclusions: This proposed new engineered surgical approach is aimed at the early treatment of large disruptive lesions of the BP. Its experimental testing in the sheep gives important clues for human translation thanks to the dimensions of the plexus which is similar in both species. The engineered device offers a way to standardize, simplify and abbreviate surgery in this demanding district.
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