What Causes Facial Nerve Palsy?

Patient Presentation
An 11-year-old female’s mother called clinic to ask when Bell’s palsy resolves after having pneumonia. After talking with the mother on the telephone a clinic appointment was recommended. The girl had been seen about 3 weeks previously for an upper respiratory tract infection. She was restarted on her albuterol for her intermittent asthma. Two days later she returned because of ear pain and was diagnosed with left otitis media and treated with antibiotics. She was also still wheezing so a course of oral prednisone was prescribed. She was seen 1 week later at an outside urgent care facility when she was visiting relatives because of continued cough. She was diagnosed with walking pneumonia and was started on azithromycin and given another course of oral prednisone. The mother said she had noticed left eye drooping around the time that the otitis media was diagnosed but hadn’t brought it up at the visit. She had looked up the problem on the Internet and wasn’t too concerned. The eyelid drooping became worse over the next several days and then proceeded to improve. The mother took daily pictures which showed this progression and at its worse the eyelid covered about half of the normal opening. The girl said she never had any eye or facial pain, she continued to eat and drink pretty normally and didn’t have problems with speech. As she had missed several days of school because of her illnesses, the mother said no one else really noticed. The girl interjected that one of her friends had said something briefly, but no one else. They denied any other recent viral illnesses. She was only using her albuterol before bed and for exercise at that time.

The past medical history was positive for mild intermittent asthma that was worse with viral upper respiratory tract infections that required oral steroids approximately 1-2 times/year. She had a history of herpes labialis at 6 years of age, but no outbreaks since that time. The family history was positive for migraine and heart disease. The review of systems was otherwise negative.

The pertinent physical exam showed a well-appearing female with normal vital signs, who occasionally had a very mild cough in the office. Her vision was 20/20 in both eyes. HEENT showed very mild left ptosis compared to right side that would be hard to discern without prior pictures of the patient. She could lift her eyebrows and forehead, move her cheeks, mouth and clench her teeth. Her extraocular movements were intact with normal pupillary response. She could keep her eyes tightly closed, but it was slightly easier to open them on the left than right. Her left ear showed a small amount of amber colored fluid at the base. Her lungs were clear. The rest of her examination, including a full neurological examination was negative.

The diagnosis of resolving Bell’s palsy was made. As she had what appeared to be a short duration of symptoms and significant resolution already, plus two courses of steroids and not appear to have any other deficits, the patient was sent home for continued monitoring. Her other symptoms were also markedly improved.

Facial nerve palsy has been known for centuries, but in 1821 unilateral facial nerve paralysis was described by Sir Charles Bell. Bell’s palsy (BP) is a unilateral, acute facial paralysis that is clinically diagnosed after other etiologies have been excluded by appropriate history, physical examination and/or laboratory testing or imaging. Symptoms include abnormal movement of facial nerve. It can be associated with changes in facial sensation, hearing, taste or excessive tearing. The right and left sides are equally affected but bilateral BP is rare (0.3%). Paralysis can be complete or incomplete at presentation. All ages can be affected but there are increased risks in the 15-45 year age group and those with diabetes, immunodeficiency or are pregnant.

Etiology is specifically unknown but felt to be caused by facial nerve edema and nerve entrapment. Some theorize that reactivation of herpes simplex virus is a cause. Symptoms tend to peak about 72 hours after onset, and can be graded by the House-Brackmann facial nerve grading system which is:

I. Normal
II. Mild dysfunction – “Slight weakness noticeable only on close inspection…” No functional impairment
III. Moderate dysfunction – “Obvious but not disfiguring difference between the two sides; no functional impairment…”
IV. Moderately severe dysfunction – “Obvious weakness and/or disfiguring assymetry…” Has functional impairment
V. Severe dysfunction – “Only barely perceptible motion.” Has functional impairment
VI. Total paralysis

Overall resolution in the adult age group is cited at 70% or better, and within the pediatric age group with up to 90-100% resolution. Resolution is usually within a few weeks (around 3-4 weeks) but can be months or longer. Treatment with prednisolone within 72 hours of onset is also associated with improved resolution in adults (age 16+ years) and is considered the standard in the adult population. But there is no randomized controlled trial to date in the pediatric population. A multicentered, randomized controlled trial of prenisolone treatment for children in the emergency department is currently underway with results anticipated in 2020. In adults, treatment with antiviral medication does not appear to make significant differences in outcomes. Physical therapy and/or surgical therapy is sometimes needed.

Problems encountered with BP can include difficulty with speech, drooling, eating, self-image and interpersonal communication issues, and opthalmological problems (e.g. excessive tearing and/or eye dryness). Synkinesia or the abnormal movement of facial muscles during voluntary muscle movement of a different group of muscles, can occur. For example, a person smiles, but their eyelid droops at the same time. It is thought that synkinesia is due to abnormal regeneration and sprouting of facial nerve axons into facial muscle groups during healing. Synkinesis can cause self-esteem issues and social problems but also can be associated with muscle spasms and/or pain.

Learning Point
The differential diagnosis of facial paralysis includes:

  • Idiopathic
    • Bell’s palsy
  • Autoimmune
    • Guillian-Barre syndrome
    • Melkersson-Rosenthal
    • Multiple sclerosis
    • Sarcoidosis
  • Congenital
    • CHARGE syndrome
    • Myotonic dystrophy
    • Poland syndrome
    • Trisomy 13 and 18
    • VACTERL syndrome
    • Nerve or muscle hypoplasia or agenesis
  • Infectious
    • Bartonella henselae
    • Clostridium botulinum
    • Coxsackie
    • Diptheria
    • Fungal infection
    • Enterovirus 70
    • Epstein Barr virus
    • Herpes simplex virus
    • HIV
    • Influenza
    • Larval migrans profundus
    • Leprosy
    • Lyme disease
    • Malaria
    • Meningitis or encephalitis
    • Mumps
    • Otitis media or mastoiditis
    • Polio
    • Rubella
    • Syphilis
    • Tetanus
    • Tuberculosis
    • Varicella (Ramsay Hunt)
  • Metabolic
    • Diabetes
    • Hyperthryoidism
    • Vitamin A deficiency
  • Neoplasm
    • Acoustic neuroma
    • Neurofibroma
    • Hemangioma
    • Rhabdomyosarcoma
    • Muscle or nerve neoplasms
    • Other head and neck benign or malignant neoplasms
    • Metastatic cancers
  • Neurologic
    • Stroke
  • Otologic
    • Cholesteatoma
  • Trauma
    • Barotrauma
    • Birth trauma
    • Basilar or temporal skull fracture
    • Middle ear trauma
    • Head and neck treatment or surgery
  • Other
    • Alcoholism
    • Carbon monoxide
    • Ethylene glycol
    • Hypertension
    • Pregnancy
    • Thalidomide
    • Vascular malformation

Questions for Further Discussion
1. What type of laboratory or imaging evaluation can be considered with a patient who has facial nerve palsy?
2. What causes muscle weakness? A review can be found here
3. What causes pediatric stroke? A review can be found here

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.
Information prescriptions for patients can be found at MedlinePlus for these topics: Bell’s Palsy and Paralysis.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Youshani AS, Mehta B, Davies K, Beer H, De S. Management of Bell’s palsy in children: an audit of current practice, review of the literature and a proposed management algorithm. Emerg Med J. 2015 Apr;32(4):274-80.

Vakharia K, Vakharia K. Bell’s Palsy. Facial Plast Surg Clin North Am. 2016 Feb;24(1):1-10.

Babl FE, Mackay MT, Borland ML, Herd DW, Kochar A, Hort J, et.al. ; PREDICT (Paediatric Research In Emergency Departments International Collaborative) research network. Bell’s Palsy in Children (BellPIC): protocol for a multicentre, placebo-controlled randomized trial. BMC Pediatr. 2017 Feb 13;17(1):53.

Babl FE, Gardiner KK, Kochar A, Wilson CL, George SA, Zhang M, et.al. PREDICT (Paediatric Research In Emergency Departments International Collaborative). Bell’s palsy in children: Current treatment patterns in Australia and New Zealand. A PREDICT study. J Paediatr Child Health. 2017 Apr;53(4):339-342.

Geller TJ. Facial Nerve Palsy in Children. UpToDate. Available from the Internet at https://www.uptodate.com/contents/facial-nerve-palsy-in-children
(rev. 3/7/18, cited 2/25/19).

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa