Bell’s Palsy

Paralysis of Cranial Nerve 7 (Facial nerve)

Authors

Affiliations

Nate Yomogida, PT, DPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, PT, DPT

Doctor of Physical Therapy

B.A. in Neuroscience

• “Bell palsy is the most common peripheral paralysis of the seventh cranial nerve, with an onset that is rapid and unilateral¹.”
• “This is an idiopathic condition causing partial or complete weakness of one-half of the face along with changes in taste, sensitivity to sound, and alteration in lacrimation and salivation¹.”
• “This activity illustrates the evaluation and management of Bell palsy and explains the role of the interprofessional team in improving care for patients with this condition¹.”

²

Introduction

Bell’s Palsy is ?var:ref-bells-palsy.definition and makes up 50-60% of facial palsies².

Anatomy

• Facial nerve

• “Originates in the lower pons and exits the brainstem ventrally at the pontomedullary junction.”²

• “Facial nerve travels 20 to 30 mm in the facial canal”²

• “Longest bony course of any cranial nerve”²

• “Making it highly susceptible to trauma and compression by edema”²

Etiology

Etiology is unknown and unclear². Viral reactivity is a potential cause².

Viral infections:

• Herpes simplex virus (HSV)
• Epstein-Barr virus (EBV)
• Varicella-zoster virus (VZV)
• Mumps
• Rubella
• Cytomegalovirus (CMV)

Clinical Presentation

• Acute peripheral facial weakness²
• Symptoms typically peak within a few days
• Pain in or behind the ear²
• Numbness or tingling in the affected side of the face²
• Hyperacusis and disturbed taste on the ipsilateral anterior part of the tongue²
• Normal neurological examination²
• Bilateral idiopathic facial palsy occurs less frequently than unilateral involvement²

DDX

• Peripheral facial palsy involves all the facial muscles ipsilateral to the side of facial nerve involvement²
• Central weakness involves lower facial muscles²
• Contralateral to the lesion in the brain stem above pons and cerebral hemisphere²

Prognosis

~71% of patients with Bell’s palsy have motor function recovery completely within 6 months without treatment. By 6 months all patients should show some improvement.

Incomplete Recovery

About 1/3 of patients may have incomplete recovery and residual effects²

Residual effects:

• Sost-paralytic hemifacial spasm²
• Co-contracting muscles²
• Synkinesis:²
• Sweating while eating or during physical exertion²

Synkinesis

Synkinesis: a consequence of the facial nerve regenerating in a disorganized manner after an injury

There are 2 common patterns: Crocodile tears and Jaw-winking lacrimation of the ipsilateral eye during chewing • Jaw-winking closure of the ipsilateral eyelid when the jaw opens.

Poor prognostic factors

• Old age
• Hypertension
• Diabetes mellitus
• Impairment of taste
• Complete facial weakness

Management

• Oral corticosteroids have shown to increase rates of full recovery²
• Corticosteroids + Antiviral combination therapy has shown to decrease rates of synkinesis²

Note

Antiviral therapy alone is not effective²

Surgery interventions

According to Dr. Amaya² there is insufficient evidence on the efficacy of surgical decompression of CN7 to manage severe Bell’s palsy².

Pharmacological interventions

1.

Warner MJ, Hutchison J, Varacallo M. Bell Palsy. In: StatPearls. StatPearls Publishing; 2024. Accessed January 25, 2024. http://www.ncbi.nlm.nih.gov/books/NBK482290/

2.

Amaya R. Bell’s Palsy: Physical Therapy Management. Published online September 2025.