The Use of End-to-Side Nerve Grafts to Reinnervate the Paralyzed Orbicularis Oculi Muscle

Abstract

Facial paralysis is a serious neurologic disorder, particularly when it affects the eye. Loss of the protective blink reflex may lead to corneal ulceration and, possibly, visual loss. The purpose of this study was to compare different nerve-grafting techniques to reanimate the paralyzed eyelid. Sixteen adult dogs (25 kg each) were allocated into four groups. Denervation of the left hemi-face was performed in all cases. One dog served as a control animal (group I). Group II dogs (n = 5) underwent end-to-side coaptation of the nerve graft to the intact palpebral branch and end-to-end coaptation to the denervated palpebral branch. Group III dogs (n = 5) underwent end-to-end coaptation of the nerve graft to the intact palpebral branch and end-to-end coaptation to the denervated palpebral branch. Group IV dogs (n = 5) underwent end-to-side coaptation of the nerve graft to the intact and denervated palpebral branches. The animals were monitored for 9 months after the surgical procedures, to allow adequate time for reinnervation. The dogs were postoperatively monitored with clinical observation, electrophysiologic testing, video motion analysis, and histologic assessments. Clinical observation and electrophysiologic testing demonstrated the production of an eye blink in the denervated hemi-face in all experimental groups. There was a trend toward increased speed of reinnervation for group III animals (end-to-end coaptations). It was concluded that end-to-side coaptation can produce a contralateral synchronous eye blink in a clinically relevant, large-animal model.

Experimental Video Analysis of Eye Blink Reflex in a Primate Model

“…The tissue was stained with osmium to analyze myelinated fibers by optical microscopy, following the protocol of the Center for Electron Microscopy of UNIFESP/EPM (5). Based on work by Sundine et al (10) the findings were characterized using the following 5-level qualitative scale: L1, total absence of viable axons; L2, small axons covering less than 10% of the diameter of the nerve; L3, groups of small axons covering more than 50% of the diameter of the nerve; L4, groups of slightly larger axons covering 80% to 90% of the diameter of the nerve; and L5, normal appearance. The results of the histologic analysis are presented in the last column of Table 1.…”

“…Briefly, after receiving general anesthesia, the right FN was exposed by retroauricular incision and compressed with a standard locking clamp for 10 minutes. On Days 1,3,6,8,10,13,15,17,20,22,24, and 27 (D1, D3...D24, D27) after the injury, we collected digital image recordings (Samsung HD video camcorder SCHM20C, Samsung, Seoul, South Korea) of the facial movements of each manually restrained animal from the frontal view (with both eyes captured simultaneously). These images were transferred to a computer (Dell Inspiron 1545, Dell Inc., Round Rock, TX), and the appropriate software (Microsoft Windows Movie Maker, Microsoft Corp., Redmond, WA) was used to prepare video files for dynamic (DA) and static assessment (SA).…”

“…However, the results of these methods do not always correlate with each other, making interpretation challenging (1,2,4,9,10). Although functional methods directly evaluate the success of neural regeneration, other types of assessments can provide only indirect evidence of regeneration (8,9,11).…”

Neurorrafia término-lateral com neurotização muscular direta associada à neurorrafia término-terminal, visando à recuperação funcional do músculo alvo

“…A utilização de diversas espécies de animais para a pesquisa de regeneração de nervos é relatada na literatura, como por exemplo, o uso de coelhos (Cramer & Essen, 1995), gatos (Moldovan et al, 2006), cães (Sundine et al, 2003), camundongos (Myckatyn et al, 2004), ratos (Viterbo, 1992;Bertelli et al, 2006) e primatas (Mackinnon & Dellon, 1990;Mennen, 1998).…”

Estudo comparativo com diferentes números de pontes na neurorrafia término-lateral em ratos

“…Várias espécies animais são utilizadas no estudo de regeneração do nervo, entre eles primatas (Mennen, 1998b;Auba et al, 2006), cães (Sundine et al, 2003), gatos (Moldovan et al, 2006), coelhos (Askar et al, 2001;Jabery et al, 2003), ratos (Akeda et al, 2006;Bertelli et al, 2006) e camundongos (Myckatyn et al, 2004).…”