Bell's Palsy

DEFINITION:
  • Bell's palsy causes sudden weakness in facial muscles that makes half of the face appear to droop. smile become one-sided, and eye on that side resists closing.
  • It is due to paralysis of LMN VII nerve 
  • Bell's palsy is temporary. Symptoms usually start to improve within a few weeks, with complete recovery in about six months. 
  • Rarely, Bell's palsy can recur(4.5-15%)
  • Besides facial muscles, the nerve affects tears, saliva, taste and a small bone in the middle of your ear.
  • Most common facial palsy
  • lower motor neuron facial palsy
  • Idiopathic ipsilateral paralysis of the facial nerve
ETIOLOGY:
  • Although the exact reason Bell's palsy occurs isn't clear, it's often linked to exposure to a viral infection.
  • Viruses that have been linked to Bell's palsy include the virus that causes:
  1. Cold sores and genital herpes (herpes simplex)
  2. Chickenpox and shingles (herpes zoster)
  3. Mononucleosis (Epstein-Barr)
  4. Cytomegalovirus infections
  5. Respiratory illnesses (adenovirus)
  6. German measles (rubella)
  7. Mumps (mumps virus)
  8. Flu (influenza B)
  9. Hand-foot-and-mouth disease (coxsackievirus)
SIGN AND SYMPTOMS:
  • Rapid onset of mild weakness to total paralysis on one side of your face( occurring within hours to days)making it difficult to smile or close your eye on the affected side Facial droop and difficulty making facial expressions
  • Pain around the jaw or in or behind your ear on the affected side
  • Increased sensitivity to sound on the affected side
  • Headache
  • A decrease in your ability to taste
  • Changes in the amount of tears and saliva you produce
  • In rare cases, Bell's palsy can affect the nerves on both sides of your face
  • The onset and evolution are rapid(
  • The incidence reaches a maximum between the ages 15 and 45 years. 
  • women>men younger than 20 years and men>women older than 40 years
  • Hyperacusis (Phonophobia) occurs due to undue sensitivity to loud sounds.
  1. Stapedius muscle dampens excessive vibrations of the stapes caused by high pitched sounds in order to protect the internal ear.
  2. If this protective reflex is not elicited it indicates stapedius paralysis and results in hyperacusis.
TEST & DIAGNOSIS:
  • There's no specific test for Bell's palsy. Doctor ask patient for closing eyes, lifting brow, showing teeth and frowning, among other movement
  • Other tests, includes:
  1. Electromyography (EMG)
  2. Imaging scans. X-ray imaging, magnetic resonance imaging (MRI) or computerized tomography (CT) occasionally
COMPLICATIONS:
  • Irreversible damage to your facial nerve
  • Misdirected regrowth of nerve fibers, resulting in involuntary contraction of certain muscles.
  • Partial or complete blindness of the eye that won't close, due to excessive dryness and scratching of the cornea, the clear protective covering of the eye
TREATMENT:
  • Medications :
  • Corticosteroids(prednisone)
  • Antiviral drugs, acyclovir (Zovirax) or valacyclovir (Valtrex)
Physical therapy:(2 weeks after chemotherapy if no improvement seen)
  • Massage and exercise of facial muscles to prevent Paralyzed muscles from shrinking and shortening.
  • Also electrical stimulation of muscles is done
  • Eye care:
Artificial tears drops at daytime
Ocular ointment at night
Use of sunglasses etc
In long standing cases: Reducing the area of exposed cornea by implanting a gold weight in the upper lid (tarsorapphy) is done.
Surgery:
  • Decompression surgery (used in past )If electroneurography of facial nerve shows >90% of degeneration. When done it should be within 2 weeks of onset of palsy
  • In rare cases, plastic surgery may be needed to correct lasting facial nerve problems.
Exam Question
  • Bells palsy is due to paralysis of LMN VII nerve 
  • Bells palsy is Most common facial palsy
  • Bells palsy is lower motor neuron facial palsy
  • Bells palsy is Idiopathic ipsilateral paralysis of the facial nerve
  • Hyperacusis seen in Bells palsy
  • Hyperacusis occurs due to paralysis of Stapedius muscle supplied by facial nerve
  • 2 weeks after chemotherapy if no improvement seen electrophysio therapy is given

Don't Forget to Solve all the previous Year Question asked on Bell's Palsy