Facial nerve regeneration using silicone conduits filled with ammonia-functionalized graphene oxide and frankincense-embedded hydrogel

Background Silicone tube (ST) conduits have been accepted as a therapeutic alternative to direct nerve suturing in the treatment of nerve injuries; however, the search for optimal adjuncts to maximize the outcomes is still ongoing. Frankincense (Fr) and graphene oxide (GO) have both been cited as neuroregenerative compounds in the literature. This study assesses the efficacy of these materials using a ST conduit in a rat facial nerve motor neuron axotomy model, distal to the stylomastoid foramen. Methods Ammonia-functionalized graphene oxide (NH2-GO) and/or Fr extract were embedded in a collagen-chitosan hydrogel and were injected inside a ST. The ST was inserted in the gap between the axotomized nerve stumps. Return of function in eye closure, blinking reflex, and vibrissae movements were assessed and compared to control groups through 30 days following axotomy. To assess the histological properties of regenerated nerves, biopsies were harvested distal to the axotomy site and were visualized through light and fluorescence microscopy using LFB and anti-MBP marker, respectively. Results There was no significant difference in behavioral test results between groups. Histological analysis of the nerve sections revealed increased number of regenerating axons and mean axon diameter in NH2-GO group and decreased myelin surface area in Fr group. Using both NH2-GO and Fr resulted in increased number of regenerated axons and myelin thickness compared to the hydrogel group. Conclusions The findings suggest a synergistic effect of the substances above in axon regrowth, notably in myelin regeneration, where Fr supposedly decreases myelin synthesis.

Effects of humeral shortening on the three-dimensional configuration of the brachial plexus: a cadaveric study

This study reports the gains in length of nerves after three different humeral shortenings. Ten brachial plexuses were dissected. The lengths of the different parts of the brachial plexus were measured using a three-dimensional digitizing system after humeral shaft shortenings of 2, 4 and 6 cm and after a standardized force of 0.588 N was used to apply tension to the plexus. The feasibility of nerve suturing was studied. Humeral shortening allowed for significant gains in lengths of the musculocutaneous (42 mm), median (41 mm), ulnar (29 mm) and radial nerves (15 mm). A 2 cm humeral shortening allowed a 2 cm nerve gap to be directly sutured in 70% to 90% of cases. This study suggests that humeral shortening could allow direct suture of nerve defects, or shorten the length of nerve grafts required to bridge a gap.

Functional Results of Facial Nerve Suture after Removal of Acoustic Neurinoma: Analysis of 25 Cases

The facial nerve is sometimes severed during the removal of acoustic neurinomas, either intentionally to ensure complete removal, or unintentionally because of difficulties in identification. In such cases we have, if possible, sutured the nerve stumps microsurgically, either end to end or by use of an intervening nerve graft. We analyzed the outcome of 25 instances of facial nerve suturing in a series of 219 patients operated on for acoustic neurinoma from 1979 to 1987. The first signs of recovery appeared at an average of 12 months, and there was continued improvement for several years. Recovery was graded from 1 to 6. The anastomosis was successful in 24 of the 25 sutured nerves, in that at least some facial movement and tone were restored (Grade 5 or higher). In 11 of the 25 cases, facial appearance at rest and with movement was moderately good (Grade 2 or 3). A Grade 1 result, with no perceivable facial dysfunction, was never achieved. Typically, oral muscles showed the most improvement and frontal muscles the least. Facial appearance was better at rest than with movement, which was always complicated by some degree of synkinesis. Closure of the eye was so good in 13 of the 25 cases that neither tarsorrhaphy nor an eyelid spring was necessary. When the facial nerve is severed, intraoperative suture is recommended, because it provides a chance for moderately good restoration of facial appearance.