The Rabbit Brachial Plexus as a Model for Nerve Repair Surgery—Histomorphometric Analysis

Abstract

One of the most devastating injuries to the upper limb is trauma caused by the avulsion. The anatomical structure of the rabbit's brachial plexus is similar to the human brachial plexus. The aim of our study was to analyze the microanatomy and provide a detailed investigation of the rabbit's brachial plexus. The purpose of our research project was to evaluate the possibility of utilizing rabbit's plexus as a research model in studying brachial plexus injury. Studies included histomorphometric analysis of sampled ventral branches of spinal nerves C5, C6, C7, C8, and Th1, the cranial trunk, the medial part of the caudal trunk, the lateral part of the caudal trunk and peripheral nerve. Horizontal and vertical analysis was done considering following features: the axon diameter, fiber diameter and myelin sheath. The number of axons, nerve area, myelin fiber density and minimal diameter of myelin fiber, minimal axon diameter and myelin area was marked for each element. The changes between ventral branches of spinal nerves C5-Th1, trunks and peripheral nerve in which the myelin sheath, axon diameter and fiber diameter was assessed were statistically significant. It was found that the g-ratio has close value in the brachial plexus as in the peripheral nerve. The peak of these parameters was found in nerve trunks, and then decreased coherently with the nerves travelling peripherally. Anat Rec, 298:444-454, 2015. V C 2014 Wiley Periodicals, Inc.Key words: brachial plexus; spinal nerve; peripheral nerve; rabbit anatomyAvulsion of ventral branches of spinal nerves C5-Th1 belongs to the most challenging and difficult reconstructive surgery procedures. Trauma caused by the avulsion is one of the most devastating injuries to the upper limb (De S a et al., 2004). To improve the results of surgical treatment the animal model can be a very useful investigative tool. Previous studies focused mainly on rats and were performed on the long branches brachial plexus.

Ultrasound and gross anatomy of the brachial plexus and major nerves of the forelimb. An anesthetic approach using the domestic rabbit (Oyctolagus cuniculus) as an experimental model1

“…In all rabbits, the ulnaris nerve was consistently the largest nerve structure in this area. The same finding has been reported in dogs and cats 2,6 . In this approach, recently some researchers have been studying the ultrasound guided mid-humeral block of the radial, ulnar, median and musculocutaneous nerves (RUMM block) in dogs with success in orthopedic surgery 15 .…”

“…comparing our anatomic results with those of other studies performed with different species 2,6 . In our study, we observed that the roots of the brachial plexus (C5, C6, C7, C8 and T1)…”

“…We believe that the rabbit can be an experimental model for studies related to the BP, since the anatomical structure of rabbits' brachial plexus is similar to that in other domesticated animals 5 as well as humans 6 . Furthermore, they have adequate size, are docile and easy to handle.…”

“…However, Visualization of the BP using ultrasonography has been previously described in humans 4 , dogs 5 , and cats 2 . To improve the results of locorregional anesthesia, animal models can be very useful investigative tools 6 . In the choice of the experimental model, besides the possibility of carrying out anesthetic procedures on the nerve branches, the basic criterion is the ability to objectively evaluate the results.…”

Collateral sprouting axons of end-to-side nerve coaptation in the avulsion of ventral branches of the C5-C6 spinal nerves in the brachial plexus

“…For rabbits, this ratio is 0.59-0.63 at the root level, 0.62-0.65 at the trunk level, and 0.63 in the suprascapular nerve [44]. Comparison of these results with those obtained using healthy limbs appears to be sufficient to assess conduction ability.…”