Electromyography and Facial Paralysis

The facial motor system is responsible for functions critical to physical, social and psychological well-being (VanSwearingen & Brach, 1996). Facial nerve paralysis is a lifealtering clinical condition, with functional, aesthetic and communication implications for the individuals who are afflicted (Hadlock, 2008). It differs from most other clinical conditions in that it is the end result of a very wide variety of underlying conditions; ranging from skull base trauma, congenital syndromes, skull base tumors, infectious diseases, among others, leading to a single disability (Diels, 2000; Hadlock, 2008). Several studies have presented conflicting results regarding its epidemiology. The precise annual incidence of Bell’s palsy, the most common cause of unilateral facial weakness, in the Western world is probably around 20 to 25 per 100,000 people (Peitersen, 1982; Morgan & Nathwani, 1982). Bell’s palsy is defined as isolated, sudden, peripheral facial paralysis of unknown etiology. However, it is generally accepted that it is a nonsuppurative, inflammatory, generative disease of the facial nerve within the stylomastoid foramen (Proctor, Corgill & Proud, 1976). The vast majority (around 80-84%) of patients will recover completely, but a few (16-20%) will remain with chronic facial paralysis or paresis (Peitersen, 1982; Morgan & Nathwani, 1982). Although Bell’s palsy may develop at any age, literature often points that it is more common among young or middle-aged adults (onset between 31-60 years) (Kukimoto et al., 1988; Gonçalves-Coelho et al., 1997; Bradbury, Simons & Sanders, 2006). The longer the recovery is delayed, the higher is the incidence of sequelae such as synkinesis and contracture (Ghali, MacQuillan & Gorbbellaar, 2001). Completeness of recovery also decreases with age with 90% complete remission up to the age of 14 compared below 40% for the over 60 age group (Peitersen, 1982). Results about distribution between genders are also conflicting. While a few authors point that the disease is equally distributed between genders (Morgan & Nathwani, 1982), others point that it is more common among females (Bradbury, Simons & Sanders, 2006; Garcia et al., 2010). Literature indicates that head trauma is the second most frequent cause of facial paralysis (Atolini Junior et al., 2009; Pinna, Testa & Fukuda, 2004). Causes of head trauma are usually related to traffic injuries (82.5%), fall from height (7.5%), assault (5%), and gunshot (2.5%), although numbers can vary significantly from one country to the next (Pinna, Testa & Fukuda, 2004; Odebode & Ologe, 2006). Until the end of the 19th century, the treatment of facial paralysis involved non-surgical means such as ointments, medicines and