**1. Introduction**

Microsurgery on human vocal folds typically involves the removal of benign lesions, often results in the creation of wounds in the form of epithelial micro-flaps (Benninger, Alessi et al. 1996). Conventionally, these micro-flaps are left to epithelialize without formal closure, which can result in healing by secondary intention and increased scar tissue formation (Woo 1995; Thekdi and Rosen 2002). Scar tissue in the lamina propria of the vocal fold affects its visco-elastic and vibrational properties (Bless and Welham 2010), disrupting the mucosal wave and often manifesting as hoarseness and a reduction in the phonatory capabilities of the patient (Thibeault, Gray et al. 2002). Since the precision of epithelial approximation accomplished during the surgical procedure and retained during the healing process affects the amount of scar tissue formation (Woo 1995), wound closure is of particular interest in voice microsurgery.

Extensive work has focused on improving wound closure methods to minimize scar tissue formation, ranging from micro-suturing which allows for primary healing (Woo 1995; Tsuji, Nita et al. 2009), to the use of tissue adhesives like fibrin glue (Bleach, Milford et al. 1997; Flock 2005; Kitahara, Masuda et al. 2005; Finck, Harmegnies et al. 2010; Skodacek, Arnold et al. 2011), and the use of chemical agents (Campagnolo, Tsuji et al. 2010) like Mitomycin-C (Branski, Verdolini et al. 2006; Fonseca, Malafaia et al. 2010) or stem cells (Hong, Lee et al.) to enhance the healing process of vocal fold wounds. However, various challenges faced in the execution of voice microsurgery add to the complexity of wound closure. These include limitations in instrument movement imposed by the laryngoscope, reduced tactile feedback in surgical instruments and loss of stereopsis. These are just some of the common challenges that can add to the intricacy of the closure of a simple wound, resulting in an increase in operation duration and associated risks under general anesthesia.

With this in mind, experimental evaluations of proposed microsurgical techniques are a necessary step in their development and optimization. Due to the rarity of human specimens for experimentation, different animal and synthetic models have been utilized instead. In this chapter, we discuss various vocal fold wound closure techniques as well as the models and methods used to evaluate them experimentally.

Investigation of Experimental Wound Closure Techniques in Voice Microsurgery 117

technique. This coupled with the increased cost of equipments, maintenance, additional personnel and their training (Yan, Olszewski et al. 2010), has driven the continued use of

Access to the vocal folds for microsurgery typically utilizes suspension laryngoscopy (Zeitels, Burns et al. 2004), where a rigid laryngoscope inserted via the patient's oral cavity provides a direct view of the vocal folds. The laryngoscope is suspended over the patient's chest, freeing the surgeon's hands for operating. A binocular operating microscope is used to provide magnification. Due to the prohibitive space constraints of laryngoscopes, microlaryngeal instruments are thin and long to access the lesion while maximizing of the surgical field. A significant level of dexterity is needed to handle the microlaryngeal tools, especially considering the fragile structure of the vocal fold. However cold surgery allows for tactile feedback and is better utilized in techniques like the micro-flap excision of benign vocal fold lesions (Zeitels 1996), which we will focus on for the course of this chapter.

The microflap technique has been accepted as the standard approach for cold surgical removal of benign vocal fold lesions (Ford 1999; Hochman and Zeitels 2000; Lee and Chiang 2009), achieving the main principles of vocal fold surgery by minimal tissue excision, minimal trauma to SLLP and epithelium. This technique typically involves the initial creation of an epithelial incision beside the lesion. Blunt dissection is used to elevate the microflap while taking care to minimise trauma to the deeper layers of the lamina propria. Only pathologic tissue is excised and the microflap is then reapproximated (Sataloff, Spiegel

Fig. 1. Microflap technique in practise, (Left) after removal of benign lesion and (right)

Following excision of the lesion, the microflap is redraped to promote primary healing (Hochman and Zeitels 2000). If there is loss of epithelium or dislodgement of the microflap,

traditional "cold" voice microsurgery techniques.

**2.2.1 Microflap technique** 

et al. 1995) as seen in Figure 1.

redraping of microflap.

**2.3 Wound closure** 
