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Topic: Peripheral Nerve Repair and Regeneration

Sensory protection to enhance functional

recovery following proximal nerve injuries:

current trends

Boa Tram Nghiem, Ian C. Sando, Yaxi Hu, Melanie G. Urbanchek, Paul S. Cederna
Department of Surgery, Section of Plastic and Reconstructive Surgery, University of Michigan Health System, Ann Arbor,
MI 48109, USA.
Address for correspondence: Dr. Paul S. Cederna, Department of Surgery, Section of Plastic and Reconstructive Surgery , University of
Michigan Health System, Ann Arbor, MI 48109, USA. E-mail: cederna@med.umich.edu

ABSTRACT
Proximal nerve injury can lead to devastating functional impairment. Because axonal regeneration is
slow, timely reinnervation of denervated muscle does not occur. These denervated muscles atrophy
and lose function. Sensory protection is a surgical technique thought to prevent denervated muscle
impairment using local sensory nerves to provide trophic support to the muscle until motor nerves can
regenerate, and neuromuscular junctions are reestablished. We performed a comprehensive literature
search using multiple databases to find primary articles reporting on the outcomes and treatment of
sensory protection. This paper reviews the three main approaches to sensory protection: (1) end-to-end
neurorrhaphy, (2) end-to-side neurorrhaphy, and (3) direct muscle neurotization. It discusses the
evidence supporting each technique and outlines goals for future investigations.
Key words:
Denervation, muscle, nerve, neurorrhaphy, protection, regeneration, sensory

INTRODUCTION window, one should consider alternative approaches
to protect the muscle before irreversible structural or
Approximately, 65% of peripheral nerve injuries occur in functional impairments occur.
the upper extremity. Healthy males between the ages of 18 When nerve transection is not amenable to primary
and 35 are most commonly affected and the majority of tensionless neurorrhaphy, the gold standard for repair
peripheral nerve injuries are caused by trauma or malignant is early nerve reconstruction using autologous nerve
disease. Axonal regeneration is slow, and there is a critical grafting. This method is not always feasible, however,
[1]
[6]
window for muscle reinnervation before the denervated due to delays in operative management, limitations of the
muscle becomes permanently impaired. Two months after donor nerve, including insufficient graft length or diameter,
[2]
injury, the denervated muscle exhibits reduced motor units or morbidity to the donor site. Alternative approaches to
but does not demonstrate changes in muscle fiber. [3,4] After early autologous nerve repair include use of decellular
6 months, however, the muscle experiences irreversible xenografts, synthetic grafts, or sensory protection.
muscle atrophy and weakness. [4,5] If primary repair cannot
reestablish motor endplate connections within this critical Sensory protection is used to prevent denervated muscle
from atrophy and subsequent functional loss. Temporarily
Access this article online protecting denervated muscle or “babysitting” it with a
Quick Response Code: nearby branch of a motor nerve successfully maintains the
Website: muscle viability. At a second surgery, the babysitter nerve
[7]
www.parjournal.net
is replaced with a nerve with the needed control once
that residual end has elongated, and neurorrhaphy can be
DOI: performed. [2,8] Similar babysitting with a sensory nerve is
10.4103/2347-9264.156982 also a way to maintain muscle viability. A sensory nerve
[9]
is coapted to the motor nerve stump in close proximity

202 Plast Aesthet Res || Vol 2 || Issue 4 || Jul 15, 2015