Facial Nerve Palsy

Authors:

Tasneem Kousar MBBS,

Abeer Sarwar MBBS,

Junaid Kalia MD

Introduction

• Facial (nerve) palsy is a neurological condition in which the function of the facial nerve (cranial nerve VII) is partially or completely lost.

• It is often idiopathic but in some cases, specific causes such as infections or trauma can be identified.

Types of Facial Nerve Palsy

• Central or Upper

• Peripheral or Lower

Etiology

• The most common cause of facial nerve palsy is Bell’s Palsy.

• Idiopathic disease is the second most common cause

• Other causes of sudden one sided facial nerve paralysis include a traumatic head injury, stroke, viral infection such as herpes simplex or herpes zoster

• Rare cause includes Lyme disease and Sarcoidosis

Pathophysiology

• The facial muscles are innervated peripherally (infra nuclear innervation) by the ipsilateral 7th cranial nerve and centrally (supra nuclear innervation) by the contralateral cerebral cortex.

• Central innervation tends to be bilateral for the upper face (e.g, forehead muscles) and unilateral for the lower face.

• Peripheral lesions (facial nerve palsy) tend to affect the upper face more than central lesions (e.g, stroke) do.

• Central and peripheral lesions tend to paralyze the lower face.

Figure 1: Showing distribution of facial muscles paralysis following upper motor and lower motor facial nerve palsy

Table 1: Differences between the lesions of the Facial Nerve

Sign and symptoms

• pain behind the ear

• paresis

• affected side becomes flat and expressionless

• ability to wrinkle the forehead, blink and grimace is limited or absent

• in severe cases, peripheral fissure widens and the eye does not close

• conjunctiva irritation

• corneal drying

Clinical Examination

• Sensory examination is normal.

• External auditory canal and a small patch behind the ear (over the mastoid) may be painful to the touch.

• If the nerve lesion is proximal to the geniculate ganglion, salivation, taste, and lacrimation may be impaired, and hyperacusis may be present.

Diagnosis

• Chest x-ray or CT .

• Serum angiotensin-converting enzyme (ACE) levels to check for sarcoidosis.

• Serum glucose is measured to check for diabetes

• MRI if onset was gradual or other neurologic deficits are present.

• Diagnosis is mainly clinical.

Prognosis

• In idiopathic facial nerve palsy, the extent of nerve damage determines outcome.

• If some function remains, full recovery typically occurs within several months.

• Nerve conduction studies and electromyography are done to help predict outcome.

• The likelihood of complete recovery after total paralysis is 90% if nerve branches in the face retain normal excitability to supramaximal electrical stimulation and is only about 20% if electrical excitability is absent.

• Chronic disuse of the facial muscles may lead to contractures and may result in permanent cosmetic damage in 10%.

Treatment

• Corneal drying must be prevented by frequent use of
• Natural tears
• isotonic saline or methylcellulose drops intermittent use of tape or a patch to help close the eye. Tarsorrhaphy is occasionally required.

• In idiopathic facial nerve palsy (Bells Palsy),
• Corticosteroids, if begun within 48 hours after onset, result in faster and more complete recovery.
• Prednisone 60 to 80 mg orally once a day is given for 1 week, then decreased gradually over the 2nd week.
• Antiviral drugs effective against herpes simplex virus
• (eg, valacyclovir 1 g orally 3 times a day for 7 to 10 days, famciclovir 500 mg orally 3 times a day for 5 to 10 days, acyclovir 400 mg orally 5 times a day for 10 days).

• F/U recommendations
• If does not show improvement in 57 days follow up with PCP right away

• Recent data suggest that antiviral drugs provide no benefit.

Continuity of Care

• Inpatient and Outpatient Neurology Follow up

• Outpatient PCP Follow up

• Eye patch for sleep

• Artificial tears as needed

• Order therapies as indicated (Physical, occupational &/or Speech)

Bibliography

• Diagnosing facial nerve paralysis. Patient Care at NYU Langone Health. (n.d.). Retrieved September 24, 2021, from https://nyulangone.org/conditions/facial-nerve-paralysis-in-adults/diagnosis.

• Facial nerve paralysis " learn ENT online " facial nerve paralysis. Learn ENT Online. (2020, October 25). Retrieved September 24, 2021, from https://www.entlecture.com/facial-nerve/.

• Facial Nerve Palsy (Bell Palsy; Bell's Palsy) By Michael Rubin, By, Rubin, M., & Last full review/revision Sep 2020| Content last modified Sep 2020. (n.d.). Facial nerve palsy - neurologic disorders. Merck Manuals Professional Edition. Retrieved September 24, 2021, from https://www.merckmanuals.com/professional/neurologic-disorders/neuro-ophthalmologic-and-cranial-nerve-disorders/facial-nerve-palsy.