Facial Paralysis Case File

Facial Paralysis Case File

Eugene C. Toy, MD, Ericka Simpson, MD, Pedro Mancias, MD, Erin E. Furr-Stimming, MD

CASE 35

A 68-year-old woman presents with right facial droop. She reports waking up this morning and having trouble eating breakfast, as food slipped out of her mouth. Her husband complains that her speech is difficult to understand. She denies numbness or tingling of her face, change in vision, or weakness or sensory changes involving her extremities. Her medical history is unremarkable, although she does have a history of chicken pox as a child. Physical examination reveals right-sided facial paralysis involving the upper and lower face. She has clear nasolabial asymmetry as well as difficulty closing the right eye and elevating the right forehead. There are multiple vesicular, erythematous blisters over her right external ear. The examination of the ear canal is painful to her, but the tympanic membrane is intact. No pus is seen in the ear canal. Hearing is mildly diminished in the right ear relative to the left. The examination of the nose, oral cavity, throat, and neck is normal. The remainder of the cranial nerve (CN) examination as well as the general examination is unremarkable.

▶ What is the most likely diagnosis?

▶ What is the next diagnostic step?

▶ What is the next step in therapy?

ANSWERS TO CASE 35:

Facial Paralysis                                                  

Summary: A 68-year-old, otherwise healthy woman presents with sudden-onset right-sided facial paralysis and right-sided hearing loss. Facial weakness involves the upper and lower face on the right. There is a vesicular rash over the right external ear.

• Most likely diagnosis: Herpes zoster oticus (Ramsay Hunt syndrome)
• Next diagnostic test step: Tzanck smear, audiogram; consider facial nerve electrodiagnostic studies, and diagnostic imaging, if indicated
• Next therapeutic step: Corticosteroid and antiviral therapy

ANALYSIS

Objectives

1. Describe the clinical presentation and diagnostic approach to facial weakness.
2. Compare and contrast central and peripheral causes of facial paralysis.
3. Know the differential diagnosis of facial weakness.
4. Know the treatment for Ramsay Hunt syndrome.

Considerations

This patient with a history of chicken pox as a child presents with blisters on her ear, hearing abnormalities, and unilateral facial paralysis. Her upper and lower facial muscles are involved, suggestive of a peripheral facial nerve palsy, as central defects generally spare muscles of the forehead. Her right-sided hearing loss is worrisome for involvement of the right CN VIII. This constellation of findings is most consistent with Ramsay Hunt syndrome, which is reactivation of latent herpes zoster infection affecting both VII and VIII CNs. In the setting of a right-sided peripheral seventh nerve palsy alone, we might expect to find hyperacusis (increased hearing) on the right side. This is due to innervation of the stapedius muscle by branches of CN VII, which normally dampens and attenuates loud sounds.

APPROACH TO:

Facial Nerve Paralysis                                      

DEFINITIONS

AUDIOGRAM: A test that measures the level of hearing in each ear.

BELL PALSY: Idiopathic facial paralysis due to seventh peripheral CN palsy, sometimes associated with herpes simplex virus (HSV).

CHOLESTEATOMA: A benign tumor composed of epithelial debris from the tympanic membrane that becomes trapped in the middle ear.

POSTHERPETIC NEURALGIA: Neuropathic pain resulting from resolved herpes infection.

TZANCK SMEAR: Slide preparation for visualization of intracytoplasmic particles due to viral infection.

VESICLES: Small fluid-filled blisters on an erythematous base.

CLINICAL APPROACH

Facial weakness is among the most common neurologic presentations in the clinic or hospital setting. Understanding the anatomy and function of the facial nerve is important in narrowing the otherwise broad differential diagnosis for facial palsy. In the setting of unilateral facial weakness, the first clinical step is to distinguish central (upper motor neuron [UMN]) from peripheral (lower motor neuron [LMN]) causes. The facial nerve (CN VII) is a multimodal nerve involved with facial expression, taste (anterior two-thirds of tongue), auditory attenuation, lacrimation, salivation, and cutaneous sensory input from the outer ear canal and part of the outer ear. Efferent fibers of CN VII (LMN) originate from the facial motor nucleus in the lower pons. These fibers, in turn, supply the muscles of facial expression as well as the stapedius muscle, which attenuates loud sounds. The facial motor nucleus is organized topographically, such that fibers to the upper one-third of the face originate from the dorsal part of the nucleus, while those to the lower two-thirds of the face originate from the ventral part of the nucleus. Corticobulbar tract fibers (UMN) provide bilateral cortical input to the dorsal part of the nucleus, while the ventral nucleus receives contralateral input only. Subsequently, lesions to the corticobulbar tract (UMN) will cause lower facial weakness, generally sparing the forehead. In contrast, lesions of CN VII after it has exited the facial motor nucleus will produce weakness of the whole face, including the forehead. In addition to involvement of the forehead, other features suggestive of peripheral/LMN facial lesions include ipsilateral hyperacusis (branch to stapedius), ipsilateral loss of taste in the anterior two-thirds of the tongue, and ipsilateral sensory deficit over the outer ear (auricle).

Because the facial nerve passes through the middle ear and temporal bone, examination of the ear canal and tympanic membrane is important. Otitis media and cholesteatoma can be associated with facial paralysis. Acute otitis media is a common cause of isolated facial paralysis in children.

Cholesteatoma is a benign tumor of epithelial debris that is produced when the squamous layer of the eardrum is trapped and cannot exfoliate properly. Cholesteatoma usually occurs in patients who have preexisting ear problems, and physical examination may reveal either cheesy epithelial debris in the ear canal or a pearly white tumor behind the ear drum. Generally, patients with cholesteatoma will have a preexisting history of hearing loss and often a long history of intermittent foul-smelling, purulent otorrhea. Cholesteatomas grow slowly and sometimes can be present for years without producing symptoms.

Facial neuromas (schwannomas of the facial nerve) are relatively rare benign tumors of the facial nerve that grow slowly and produce a slowly progressive (over several months, not days) form of facial paralysis.

Tumors of the parotid gland and skull base can produce facial paralysis. Paralysis of an isolated branch of the facial nerve should raise suspicion for malignancy. Malignant tumors of the skin or parotid gland can produce facial paralysis either by compression or perineural invasion. Bilateral facial paralysis has a limited number of causes, including Lyme disease and sarcoidosis, which may affect multiple cranial nerves. Also, patients with Guillain-Barre’ syndrome may present with unilateral or bilateral facial paralysis.

Ramsay Hunt syndrome is caused by reactivation of varicella zoster virus (VZV) in the geniculate ganglion, the main sensory ganglion of CN VII. Reactivation of the virus produces vesicles in its area of sensory innervation. For the facial nerve, this can include the posterior ear canal or postauricular skin. Reactivation can occur in the setting of immunocompromise or due to nonspecific physiology.

Ramsay Hunt syndrome may also involve other CNs, including VIII, IX, V, and VI, in order of frequency. The pain from herpes zoster is often described as burning and can be intensely painful.

Treatment of Ramsay Hunt syndrome involves oral acyclovir and corticosteroids, with faster resolution of symptoms if initiated within 48 hours of onset. Carbamazepine, pregabalin, or gabapentin may also be useful in treating associated neuropathic pain. Of note, patients with active vesicles are contagious and can spread the virus to susceptible individuals.

Hearing loss and/or vestibular symptoms can occur in patients with Ramsay Hunt syndrome. This will produce ipsilateral sensorineural hearing loss. Proposed mechanisms for involvement of CN VIII include periganglionic spread and compression due to secondary inflammatory changes and edema.

Bell palsy refers to idiopathic facial nerve palsy, often associated with viral infection with HSV. In contrast to Ramsay Hunt syndrome, which may cause ipsilateral hearing loss due to involvement of CN VIII, Bell palsy is associated with ipsilateral hyperacusis secondary to attenuation deficits from stapedius muscle involvement. With regard to treatment, corticosteroids have been shown to increase the likelihood of recovery in Bell palsy. In contrast, antiviral therapy has not been shown to improve outcomes and is not evidence-based medicine for treatment in Bell palsy. Current recommendations are for steroids alone; treatment should be initiated within the first 72 hours of symptoms.

Regardless of the cause, patients with facial paralysis (particularly LMN lesions) need special care of the eye on the affected side. Because of the loss of the blink reflex and decreased lacrimation, the affected eye can dry out and produce exposure keratoconjunctivitis, which may lead to loss of vision in the affected eye. Simple eye care consisting of artificial tears every hour while awake and lubricant ointment at night with eye taping can prevent permanent loss of vision.

CASE CORRELATION

• See also Case 32 (Posterior Communicating Artery Aneurysm), Case 34 (Sixth Nerve Palsy [Ischemic Mononeuropathy]), and Case 36 (Ptosis [Myasthenia Gravis])

COMPREHENSION QUESTIONS

35.1 A 49-year-old woman is noted to have right-sided facial weakness of acute onset. What is the most common cause of this patient’s condition?

A. Lyme disease

B. VZV reactivation

C. Acoustic neuroma

D. HSV reactivation

E. Noncaseating granulomas

35.2 What is the key indicator of Ramsay Hunt syndrome?

A. Vesicles on an erythematous base found in the external ear

B. Noncaseating granulomas on lower lip biopsy

C. Circulating antibodies to Borrelia burgdorferi

D. Uveitis and parotid gland swelling

E. Loss of taste on the ipsilateral tongue

35.3 A 69-year-old man complains of acute-onset right facial droop. A close examination of his facial movements indicates loss of the nasolabial fold and inability to raise the upper lip on that side. His blink, forehead, and lower lip movement are normal. What is the most likely cause of his facial paralysis?

A. Bell palsy

B. Stroke

C. Malignant parotid gland tumor

D. Acoustic neuroma

E. Lyme disease

ANSWERS

35.1 D. By far the most common cause of acute facial weakness in an adult is Bell palsy. This disorder is considered to be associated with reactivation of HSV. However, this is a diagnosis of exclusion, as no accurate serologic tests have been discovered that confirm the diagnosis.

35.2 A. The pathognomonic feature of herpes zoster oticus (Ramsay Hunt syndrome) is a vesicular eruption on an erythematous base in an area of facial nerve sensory distribution (external ear). This disorder is caused by reactivation of VZV and is treated with antiviral medications and steroids. Inadequately treated zoster infections can lead to poor recovery of facial function and postherpetic neuralgia.

35.3 B. Strokes affecting corticobulbar pathways may present as a partial facial paralysis. Because strokes are central, there is sparing of the forehead. Incomplete facial nerve palsy or involvement of an isolated facial nerve branch(s) is also worrisome for malignancy but would likely be subacute in presentation. Bell palsy, herpes zoster oticus, and Lyme disease generally affect the entire nerve. Acoustic neuromas can cause facial paralysis when they are large, but this is very rarely seen in the modern area. Their location in the cerebellopontine angle would produce whole face weakness, not an isolated branch weakness as described.

    CLINICAL PEARLS    

▶ Bell palsy is the most common cause of acute, unilateral facial weakness in adults. ▶ Facial paralysis with vesicles on an area of facial nerve sensation is pathognomonic for herpes zoster oticus (Ramsay Hunt syndrome). ▶ An isolated facial nerve branch weakness should prompt evaluation for malignant tumor compressing the nerve if stroke workup is negative. ▶ Patients with facial paralysis or paresis should be given instructions regarding eye care and moisturization to avoid exposure keratopathy. ▶ Steroid and antiviral medications should be given to patients with Ramsay Hunt syndrome. Treatment for Bell palsy is steroids alone and should be initiated within 72 hours of symptom onset.

REFERENCES

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Austin JR, Peskind SP, Austin SG, et al. Idiopathic facial nerve paralysis: a randomized double-blind controlled study of placebo versus prednisone. Laryngoscope. 1993;103(12):1326-1333. 

Gilden DH, Cohrs RJ, Hayward AR, et al. Chronic varicella-zoster virus ganglionitis—a possible cause of postherpetic neuralgia. J Neurovirol. 2003;9(3):404-407. 

House JW, Brackmann DE. Facial nerve grading system. Otolaryngol Head Neck Surg. 1985;93(2): 146-147. 

Kuhweide R, Van de Steene V, Vlaminck S, et al. Ramsay Hunt syndrome: pathophysiology of cochleovestibular symptoms. J Laryngol Otol. 2002;116(10):844-848. 

Ohtani F, Furuta Y, Aizawa H, et al. Varicella-zoster virus load and cochleovestibular symptoms in Ramsay Hunt syndrome. Ann Otol Rhinol Laryngol. 2006;115(3):233-238. 

Overell JR, Willison HJ. Recent developments in Miller Fisher syndrome and related disorders. Curr Opin Neurol. 2005;18(5):562-566. 

Redaelli de Zinis LO, Gamba P, Balzanelli C. Acute otitis media and facial nerve paralysis in adults. Otol Neurotol. 2003;24(1):113-117. 

Ronthal M. Bell’s palsy: prognosis and treatment in adults. UpToDate. http://www.uptodate.com/contents/bells-palsy-prognosis-and-treatment-in-adults#references. Accessed December 1, 2016. 

Sweeney CJ, Gilden DH. Ramsay Hunt syndrome. J Neurol Neurosurg Psychiatry. 2001;71(2):149-154.

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