HSC Section 3 - Trauma, Critical Care and Sleep Medicine

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infection via saliva, the virus becomes latent in the sensory ganglia. Viral insult causes inflammation of the facial nerve, thought to result in ischemia centered at the labyrin- thine segment of the facial nerve within the temporal bone. 17,18 VZV is more virulent and associated with delayed recovery compared with HSV-associated FP. Gadolinium-enhanced MRI shows unilateral enhancement of the facial nerve at the meatal region, 18,19 a physiologic bottleneck where inflammation compresses and causes ischemia to the nerve. Seventy-one percent of patients with BP recover completely without treatment. 1 An improved prognosis is seen in cases of incomplete paralysis, age younger than 14 years, intact taste, intact stapedius reflex, intact tearing, absence of postauricular pain, and signs of recovery within 3 weeks. Poor prognostic indicators include diabetes, preg- nancy, advanced age (>60), hypertension, and complete facial flaccidity at onset.

OTHER ACQUIRED CAUSES OF ACUTE FACIAL PARALYSIS

BP is the most common cause of acute FP. After this designation, the literature varies on the next common causes depending on the center and their referral patterns. 1,2 The following is a general sampling of other causes of FP.

Other Infectious Causes Varicella zoster virus

VZV–associated FP represents one form of viral FP. 1 Herpes zoster oticus or RHS has a poor prognosis with delayed recovery compared with BP. RHS is characterized by unilateral FP, pain, cochleovestibular symptoms (sensorineural hearing loss), and ves- icles in a segmental pattern ( Fig. 3 ). Patients older than 45 years are more commonly affected and will have a more complete facial palsy. Vesicles are typically located in the concha or external ear canal; however, any distribution including cranial nerves 5, 9, and 10 and cervical nerves are possible. The vesicles may not appear simulta- neously with the palsy. Zoster sine herpete occurs with an absence of vesicles and may make the diagnosis more difficult. Treatment includes high-dose corticosteroid and antiviral medication. Without treatment, only 21% will fully recover. 1

Fig. 3. RHS with left ear conchal vesicles, erythema, and edema and left tongue edema in patient with herpes zoster infection and left acute FP. She also has ipsilateral acute sensori- neural hearing loss.

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