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Year : 2021  |  Volume : 69  |  Issue : 2  |  Page : 326--327

Nerve Guidance Conduits: Journey of a Thousand Miles in Search of a Destination

Manish Sharma 
 Department of Neurosurgery, Mayo Clinic Health System, Mankato, Minnesota, USA

Correspondence Address:
Manish Sharma
1025, Marsh Street, Mankato, Minnesota - 56001

How to cite this article:
Sharma M. Nerve Guidance Conduits: Journey of a Thousand Miles in Search of a Destination.Neurol India 2021;69:326-327

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Sharma M. Nerve Guidance Conduits: Journey of a Thousand Miles in Search of a Destination. Neurol India [serial online] 2021 [cited 2021 Jun 18 ];69:326-327
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Singh et al. compare the functional results after sciatic nerve transection in 24 healthy Sprague Dawley rats.[1] In Group B, a 1 cm length of the sciatic nerve was excised and reverse anastomosed using 10-0 monofilament suture. In Group C, this gap was bridged by a silicone conduit that was made in house. Standard parameters were compared as was histopathological. Both test groups revealed poor and subnormal recovery with incomplete axonal regeneration. The authors concluded that a silicone conduit graft may be an economical and effective alternative to presently available interposition grafts to bridge short segment gaps. The authors are to be congratulated for providing us with animal model data from the Indian subcontinent, which is admittedly hard to come by. Although there were no functional differences between the two groups, histopathological data indicated that axonal regeneration was better with lesser collagen fiber deposition in the silicone conduit group.

The drawbacks of the study are a small sample size precluding statistical correlation and a short follow up. A more appropriate conclusion is that the silicone conduit was as effective and safe as an autograft. Incorporating additional test groups using commercially available conduits would be an actual test of cost-effectiveness. Regrettably, details regarding the actual preparation of the silicone conduits were not available- was the diameter specific to the target and if so, how was this engineered?

The 'critical nerve gap” that is cited by the authors is controversial. A gap of 1 cm can be typically bridged by an end to end co-aption. Gaps greater than 2-3 cm need to be bridged using either autograft which remain the gold standard, processed nerve allografts (PNAs) or natural/synthetic nerve guidance conduits (NGCs).[2],[3] NGCs also known as artificial nerve conduits or artificial nerve grafts offset the disadvantages of harvesting a nerve autograft, wherein there is donor site morbidity secondary to the need for a second incision, a painful neuroma, sensory and functional loss at the donor nerve site, prolongation of operative time, limited supply and length/diameter mismatch. NGCs theoretically avoid the use of sutures secondary to the intubation technique, with a resultant decrease in scarring and a foreign body reaction. This was borne out in this study. Research in NGCs has come a long way since they were first used in 1982.[4] Several permutations and combinations exist based upon their mechanical structure and the concurrent use of biochemical and biological clues that could accelerate the rate of nerve regeneration.[5]

NGCs can be used to effectively reconstruct a digital nerve gap <2.5 cm.[2] Larger gaps, especially for mixed/motor nerves, may need an autograft versus a nerve transfer.[3],[6]

In conclusion, the journey of a thousand miles needs a destination. The destination is painless and fully functional immortality. To decrypt the code for nerve regeneration would be akin to knocking on its door.


1Singh S, Srivastava AK, Baranwal AK, Bhatnagar A, Das KK, Jaiswal S, et al. Efficacy of Silicone Conduit in the Rat Sciatic Nerve Repair Model: Journey of a Thousand Miles. Neurol India 2021;69:318-325.
2Rbia N, Bulstra LF, Saffari TM, Hovius SER, Shin AY. Collagen Nerve Conduits and Processed Nerve Allografts for the Reconstruction of Digital Nerve Gaps: A Single-Institution Case Series and Review of the Literature. World Neurosurg 2019;127:e1176-e1184.
3Huayllani MT, Boczar D, Forte AJ, Rinker B. Evidence-Based Approach to Nerve Gap Repair in the Upper Extremity: A Review of the Literature and Current Algorithm for Surgical Management. Ann Plast Surg 2020;84 (6S Suppl 5):S369-S374.
4Lundborg G, Gelberman RH, Longo FM, Powell HC, Varon S. In vivo regeneration of cut nerves encased in silicone tubes: growth across a six-millimeter gap. J Neuropathol Exp Neurol 1982;41:412-22.
5Vijayavenkataraman S. Nerve guide conduits for peripheral nerve injury repair: A review on design, materials and fabrication methods. Acta Biomater 2020;106:54-69.
6Sharma MS, Shin AJ, Bishop AT, Spinner RJ. Nerve Transfers, in Quinones- Hinojosa A, Schmidek and Sweet's Operative Neurosurgical Techniques; Indications, Methods and Results, Philadelphia, Saunders, 2012, 6th Edition, Chapter 198, Vol. 2, pp 2261-2273.