Structural or functional damage to the facial nerve can give rise to a weakness of the facial muscles known as facial nerve palsy. Infection of the facial nerve within the bony facial canal of the petrous bone causes the facial nerve to swell, giving rise to a set of clinical manifestations that are identified as the Bell’s palsy. This is the main difference between Bell’s palsy and facial palsy.
Facial palsy or facial nerve palsy is the weakness of the facial muscles following structural or functional damage to the facial nerve. When this weakness occurs following an infection of the nerve that is known as the Bell’s palsy. Therefore, Bell’s palsy is one cause of facial nerve palsy among many other causes.
CONTENTS
1. Overview and Key Difference
2. What is Bell’s Palsy
3. What is Facial Palsy
4. Similarity Between Bell’s Palsy and Facial Palsy
5. Side by Side Comparison – Bell’s Palsy vs Facial Palsy in Tabular Form
6. Summary
What is Bell’s Palsy?
Infection of the facial nerve within the bony facial canal of the petrous bone causes the facial nerve to swell. This gives rise to a set of clinical manifestations that are identified as the Bell’s palsy. In most of the cases, Herpes Simplex virus is the infective agent. Within 24-48 hours from the onset of the infection, the patient develops a lower motor type facial nerve palsy.
Clinical Features
- Weakness of one half of the face
- Pain behind the ear
- Hyperacusis
- Altered sensation of taste
Bell’s palsy is usually diagnosed clinically, and no tests are required.
Figure 01: Bell’s Palsy
Management
Patients recover completely within 3-8 weeks even without specific treatments most of the time. Treatment with corticosteroids in the early stages can be helpful in improving the outcome. Recurrence of Bell’s palsy should be investigated to identifying any underlying condition such as HIV.
What is Facial Palsy?
The facial nerve is the seventh pair of cranial nerves, and it supplies the muscles of facial expressions. It also innervates the stapedius muscle of the ear. Structural or functional damage to the facial nerve can give rise to a weakness of the facial muscles. This is known as facial nerve palsy.
Figure 02: Facial Nerves
Unilateral Facial Nerve Palsy
Unilateral facial nerve palsy can occur in two forms:
- Upper motor lesions
The upper half of the face receive sensory supply from both the facial nerves. But the lower half of the face is innervated only by the contralateral facial nerve. Therefore a unilateral upper motor nerve lesion will cause only a paralysis of the lower half of contralateral facial muscles.
- Lower motor lesions
A unilateral lower motor lesion will cause ipsilateral hemifacial paralysis.
Causes
- Tumors in the cerebellopontine angle
- Bell’s palsy
- Trauma
- Middle ear infection
- Ramsay Hunt syndrome
- Parotid gland tumors
- Stroke
Bilateral Facial Nerve Palsy
In contrast to the unilateral facial nerve palsy, there is no asymmetry in the bilateral facial nerve palsy and this makes the clinical identification of the disease bit difficult.
Causes
- Infections such as Lyme disease and HIV seroconversion
- Sarcoidosis
- Skull base trauma
- Pontine lesions
- Neuromuscular disorders such as Guillan barre and myasthenia
- Rare genetic and congenital diseases
Investigations performed for the identification of the disease and mode of management vary according to the underlying disease.
What is the Similarity Between Bell’s Palsy and Facial Palsy?
- Structural or functional damage to the facial nerve is the underlying pathology in both conditions
What is the Difference Between Bell’s Palsy and Facial Palsy?
Ptosis and Blepharoplasty |
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| Infection of the facial nerve within the bony facial canal of the petrous bone causes the facial nerve to swell. This gives rise to a set of clinical manifestations that are identified as the Bell’s palsy. | Structural or functional damage to the facial nerve can give rise to a weakness of the facial muscles. This is known as facial nerve palsy. |
| Cause | |
| Bell’s palsy is one cause of facial nerve palsy. | Causes of unilateral facial nerve palsy
Causes of bilateral facial nerve palsy
|
| Diagnosis | |
| Bell’s palsy is usually diagnosed clinically, and no tests are required. | The choice of investigations depends on the clinical suspicion of the underlying cause. |
| Treatment and Management | |
| Patients recover completely within 3-8 weeks even without specific treatments most of the time.
Treatment with corticosteroids in the early stages can be helpful in improving the outcome. Recurrence of the Bell’s palsy should be investigated to identifying any underlying condition such as HIV. |
The mode of management varies according to the underlying disease. |
Summary – Bell’s Palsy vs Facial Palsy
Structural or functional damage to the facial nerve can give rise to a weakness of the facial muscles. This is known as facial nerve palsy. On the other hand, infection of the facial nerve within the bony facial canal of the petrous bone causes the facial nerve to swell. This gives rise to a set of clinical manifestations that are identified as the Bell’s palsy. Bell’s palsy is one cause of facial nerve palsy among hundreds of other causes.
Reference:
1. Kumar, Parveen J., and Michael L. Clark. Kumar & Clark clinical medicine. Edinburgh: W.B. Saunders, 2009.
Image Courtesy:
1. “Bells palsy diagram” By Patrick J. Lynch, medical illustrator – Patrick J. Lynch, medical illustrator (CC BY 2.5) via Commons Wikimedia
2. “Head facial nerve branches” By Patrick J. Lynch, medical illustrator – Patrick J. Lynch, medical illustrator (CC BY 2.5) via Commons Wikimedia