Bell Palsy
To view the entire topic, please log in or purchase a subscription.
Medicine Central™ is a quick-consult mobile and web resource that includes diagnosis, treatment, medications, and follow-up information on over 700 diseases and disorders, providing fast answers—anytime, anywhere. Explore these free sample topics:
-- The first section of this topic is shown below --
Basics
Description
An acute, usually unilateral, peripheral facial nerve palsy of unknown etiology. Herpes-mediated viral inflammatory/immune mechanism is the likely cause of most cases, causing subsequent swelling and compression of cranial nerve VII (facial) and the associated vasa nervorum.
Epidemiology
- Affects 0.002% of the population annually
- No race, geographic, or gender predominance
- Median age of onset is 40 years but affects all ages.
- Accounts for about half of all cases of unilateral facial paralysis
- Occurs with equal frequency on the left and right sides of the face
- Most patients recover, but as many as 30% are left with facial disfigurement and pain.
Incidence
- 25 to 30 cases per 100,000 people in the United States per year
- Lowest in children ≤10 years of age; highest in adults ≥70 years of age
- Higher among pregnant women (3 times the risk)
Prevalence
Affects 40,000 Americans every year
Etiology and Pathophysiology
- Results from damage to the facial cranial nerve (VII)
- Exact pathogenesis is still controversial; infective, immune, and ischemic mechanisms are potential contributors.
- The most likely cause is activation of latent herpes virus (herpes simplex virus [HSV] type 1 and herpes zoster virus) in cranial nerve ganglia.
- Inflammation of cranial nerve VII causes edema of perineurium and subsequent compression and possibly degeneration of both the nerve and the associated vasa nervorum.
- Ischemia from microangiopathy associated with diabetes mellitus
Genetics
Reported case series suggest potential genetic predisposition, but it remains unclear which factors are inherited.
Risk Factors
- Pregnancy, especially in the 3rd trimester or in the 1st postpartum week
- Immunocompromised status
- Diabetes mellitus, possibly secondary to microvascular ischemia
- Age >30 years
- Exposure to cold temperatures
- Upper respiratory infection (e.g., coryza, influenza)
- Chronic hypertension (HTN)
- Obesity
- Migraine headache
Commonly Associated Conditions
- HSV
- Herpes zoster virus
- Lyme disease
- Diabetes mellitus
- HTN
- Ramsay-Hunt syndrome
- Sjögren syndrome
- Sarcoidosis
- Eclampsia
- Amyloidosis
-- To view the remaining sections of this topic, please log in or purchase a subscription --
Basics
Description
An acute, usually unilateral, peripheral facial nerve palsy of unknown etiology. Herpes-mediated viral inflammatory/immune mechanism is the likely cause of most cases, causing subsequent swelling and compression of cranial nerve VII (facial) and the associated vasa nervorum.
Epidemiology
- Affects 0.002% of the population annually
- No race, geographic, or gender predominance
- Median age of onset is 40 years but affects all ages.
- Accounts for about half of all cases of unilateral facial paralysis
- Occurs with equal frequency on the left and right sides of the face
- Most patients recover, but as many as 30% are left with facial disfigurement and pain.
Incidence
- 25 to 30 cases per 100,000 people in the United States per year
- Lowest in children ≤10 years of age; highest in adults ≥70 years of age
- Higher among pregnant women (3 times the risk)
Prevalence
Affects 40,000 Americans every year
Etiology and Pathophysiology
- Results from damage to the facial cranial nerve (VII)
- Exact pathogenesis is still controversial; infective, immune, and ischemic mechanisms are potential contributors.
- The most likely cause is activation of latent herpes virus (herpes simplex virus [HSV] type 1 and herpes zoster virus) in cranial nerve ganglia.
- Inflammation of cranial nerve VII causes edema of perineurium and subsequent compression and possibly degeneration of both the nerve and the associated vasa nervorum.
- Ischemia from microangiopathy associated with diabetes mellitus
Genetics
Reported case series suggest potential genetic predisposition, but it remains unclear which factors are inherited.
Risk Factors
- Pregnancy, especially in the 3rd trimester or in the 1st postpartum week
- Immunocompromised status
- Diabetes mellitus, possibly secondary to microvascular ischemia
- Age >30 years
- Exposure to cold temperatures
- Upper respiratory infection (e.g., coryza, influenza)
- Chronic hypertension (HTN)
- Obesity
- Migraine headache
Commonly Associated Conditions
- HSV
- Herpes zoster virus
- Lyme disease
- Diabetes mellitus
- HTN
- Ramsay-Hunt syndrome
- Sjögren syndrome
- Sarcoidosis
- Eclampsia
- Amyloidosis
There's more to see -- the rest of this entry is available only to subscribers.