Current Considerations in the Management of Facial Nerve Palsy
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REVIEW CURRENT OPINION Current considerations in the management of facial nerve palsy Charles Kim and Gary J. Lelli Jr Purpose of review Facial nerve palsy is a potentially devastating condition that can arise from many different causes. Appropriate management is complicated by the wide spectrum of clinical presentation and disease severity that characterizes this condition. As such, recent studies have focused on augmenting our understanding of the underlying anatomy and pathophysiology of facial nerve palsy, while also exploring different treatment options. Recent findings There have been a multitude of radiologic investigations that have delineated anatomical considerations pertinent to facial neuropathy, whereas various grading schemes and software programs have been developed to facilitate the clinical assessment of patients. Furthermore, a wide variety of medical and surgical treatment options have been proposed – whereas some are variants of previously described methods, others represent novel approaches. Summary Appropriate management of facial nerve palsy is dependent on a multitude of factors and must be tailored to patients on an individual basis. The studies summarized in this article highlight the recent advancements geared toward refining the assessment and treatment of patients with facial neuropathy. Keywords Bell’s palsy, exposure keratopathy, facial nerve palsy, facial synkinesis INTRODUCTION Ramsay Hunt syndrome, herpes simplex virus, The facial nerve (cranial nerve VII) is intimately human immunodeficiency virus, Lyme disease, and involved in the innervation of the facial muscles. meningitis, as well as conditions such as sarcoidosis As a result, any degree of dysfunction can have and Gullian–Barre syndrome. However, the vast significant functional and aesthetic ramifications. majority of cases are idiopathic in nature; in a Given the wide-reaching clinical manifestations retrospective review published in 2002, Peitersen of facial neuropathy, appropriate treatment often [1] found that 70% of facial palsy cases are ultimately involves a multidisciplinary approach. Ophthalmo- diagnosed as Bell’s palsy. logists are frequently called upon to optimize Chronic systemic conditions such as hyper- the health and function of the cornea, which can tension and diabetes mellitus have been implicated be compromised in the setting of inadequate blink- as risk factors for Bell’s palsy. Jorg et al. [2] recently ing and malpositioning of the midface and eyelid. performed a systematic review of facial neuropathy This review will focus on the current concepts in the setting of severe hypertension and found that pertinent to the ocular assessment and management this association was strongest in children – the of patients with facial nerve dysfunction. We will median age in their cases was 9.5 years. In addition, briefly review some well established treatment modalities, while highlighting medical and surgical advancements that have been published over the Department of Ophthalmology, Weill Cornell Medical College, New York, last 12 months. New York, USA Correspondence to Gary J. Lelli Jr., MD, Department of Ophthalmology, Weill Cornell Medical College, 1305 York Avenue, 12th Floor, New York, NY 10021, USA. Tel: +1 646 962 3182; fax: +1 646 962 0602; e-mail: CAUSE [email protected] Facial neuropathy can result from a wide variety Curr Opin Ophthalmol 2013, 24:478–483 of causes, including infectious processes such as DOI:10.1097/ICU.0b013e3283634869 www.co-ophthalmology.com Volume 24 Number 5 September 2013 Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Management of facial nerve palsy Kim and Lelli KEY POINTS Table 1. House–Brackmann grading system Grade Features Facial nerve palsy can arise from a multitude of causes, although most cases are idiopathic. I. Normal Normal facial function in all areas Patients with facial neuropathy can exhibit a wide II. Mild Slight weakness noticed on close inspection spectrum of clinical manifestations owing to the dysfunction complex innervation pattern of the facial nerve. No synkinesis, contracture, or hemifacial spasm Recently published radiographic studies have focused Normal symmetry and tone at rest on developing a better understanding of the underlying Moderate-to-good forehead function anatomic considerations pertinent to facial neuropathy. Complete eye closure with minimal effort A variety of nonsurgical treatment modalities, ranging Slight asymmetry of mouth from scleral contact lenses to systemic steroids, has III. Moderate Obvious but not disfiguring difference been explored and described in the literature. dysfunction between the sides Surgical management of patients with facial neuropathy Noticeable but not severe synkinesis, encompasses both static and dynamic techniques, contracture, or hemifacial spasm which are directed at addressing the periocular Normal symmetry and tone at rest changes seen in these patients. Slight-to-moderate movement of forehead Complete but asymmetric eye closure with effort Slightly weak mouth movements with Riga et al. [3] examined a group of 56 patients with maximum effort Bell’s palsy and found that patients with abnormal IV. Moderately Obvious weakness and disfiguring hemoglobin A1c values had more severe presenta- severe asymmetry tions [House–Brackmann grade V/VI (Table 1)] than dysfunction nondiabetics, although this did not appear to have Normal symmetry and tone at rest prognostic ramifications. No forehead movement Incomplete eye closure ANATOMY Asymmetry of mouth with maximum effort V. Severe Only barely perceptible motion Cranial nerve VII has a multitude of sensory dysfunction and motor functions (Table 2). The motor fibers Asymmetry at rest originate in the tegmentum of the caudal pons No forehead movement and exit at the pontomedullary junction, at which Incomplete eye closure with only slight point they run separately from the sensory fibers movement of lid with maximal effort prior to their joint entry into the internal acoustic Slight movement of corner of mouth canal as the facial nerve. & VI. Total No movement Kondo et al. [5 ] performed morphometric paralysis analyses of the facial nerve and found a significant decrease in the number of myelinated axons with Adapted with permission [4]. age (r ¼0.77; P < 0.01), perhaps explaining the increased susceptibility of elderly patients to Bell’s the canal were significantly smaller on the affected palsy, as well as their delayed recovery course. There side of patients with Bell’s palsy compared with the was no change in the transverse area of individual contralateral side. Furthermore, they also confirmed myelinated axons over time (r ¼0.01; P ¼ 0.96). that the labyrinthine segment is the most narrow In addition, there was no difference in the number portion of the facial canal. or transverse area of axons between affected and Vaid et al. [7] used HRCT and MRI to demon- unaffected sides or based on sex. strate the clinical significance of the geniculate The facial nerve runs 20–30 mm within the fossa, which they found to be involved in a multi- facial canal, representing the longest bony course tude of pathologic processes – including infections, of any cranial nerve. As a result, it is particularly trauma, schwannoma, hemangioma, meningioma, susceptible to injury from trauma and edema. and malignancy – responsible for causing facial Murai et al. [6] utilized high-resolution computed nerve palsy. Furthermore, enlargement of the geni- tomography (HRCT) with multiplanar reconstruc- culate fossa may indicate an underlying fracture tion to demonstrate that the mean cross-sectional in the setting of traumatic facial paralysis, as area of the labyrinthine and horizontal segments of demonstrated by Mu et al. [8]. 1040-8738 ß 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins www.co-ophthalmology.com 479 Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Oculoplastic and orbital surgery Table 2. Sensory and motor functions of cranial nerve VII Sensory Motor External ear (via nervus intermedius) Muscles of facial expression (including orbicularis and frontalis) Taste fibers on anterior two-thirds of tongue Posterior belly of digastric muscle (via chorda tympani) Oropharynx (below palatine tonsil) Stylohyoid muscle Stapedius muscle (middle ear) Lacrimal secretion (via pterygopalatine ganglion) Salivary secretion (via chorda tympani) Upon its exit from the stylomastoid foramen, Computer Evaluation software is an accurate and the facial nerve becomes extracranial. It passes sensitive tool for obtaining objective measures of between the superficial and deep lobes of the parotid facial position. gland, where it divides into the temporofacial The primary ocular manifestations of facial and cervicofacial trunks, prior to further division nerve palsy are related to exposure keratopathy that into the temporal, zygomatic, buccal, mandibular, can develop in response to the lagophthalmos and cervical branches. The temporal and zygomatic and paralytic ectropion often seen in these patients. branches then innervate the orbicularis oculi, As a result, careful attention must be paid to the whereas the buccal and cervical branches contribute positioning of the upper and lower eyelids, as well to supplying the inferior orbicularis. as the force, frequency, and velocity of the blink Recent studies have described different response, and the severity of lagophthalmos. approaches to accessing