Facial Nerve
Paralysis
What is a facial nerve?
Facial nerve is
the 7th of 12 cranial nerves. It emerges from the brain stem and goes through a
complex route to reach the muscles of facial expression including keeping the
eyebrows high and closure of the eyelids.
What are the causes of facial nerve
paralysis?
Facial nerve
paralysis may be congenital or acquired. Acquired causes include infection
(Bell's Palsy), vascular lesions, tumours (acoustic neuroma, parotid gland or
temporal bone tumour) or trauma (birth, temporal bone fracture).
What are the symptoms?
The paralysis
usually affects one half of the face. Patients with facial nerve paralysis
develop flattening of the affected half of the face with loss of forehead
wrinkles, inability to whistle and dragged appearance of the opposite corner of
the mouth. Eye symptoms include eyebrow drooping, elevation or retraction of the
upper eyelid, sagging and ectropion (outward turning of the lid margin) of the
lower eyelid, watering, lagophthalmos (inability to close the eye), and exposure
keratopathy (drying of the cornea ).
How is this condition managed?
Many patients can
be managed medically with lubricating eye drops and ointment using artificial
tear preparations and taping the eyelids closed at bedtime.
When is a surgical procedure
required?
Surgical
procedures may be advised for facial nerve paralysis based on each individual
case. The primary aim of treatment is to protect the cornea (coloured part of
the eye) since
it may undergo
drying due to poor lid closure and thus affect the eye sight. The other reasons
for a surgical procedure is to reduce the eye watering.
Various surgical procedures:
Lateral
Tarsorraphy
– Surgical closure of the outer portion of the eyelids will frequently suffice
to narrow the eyelid opening and decrease evaporation. Due to its poor cosmetic
result, it is often reserved for extreme situations only.
Lateral Tarsal
Strip Procedure
-This procedure involves tightening of the lower eyelid and is performed when
the eyelid is lax and sagging. The eyelid is shortened and reattached to the
bony outer orbital rim.
Medial
Canthoplasty
– This procedure may be required to pull up the sagging lower lid especially in
the inner corner.
Gold Weights
-Better closure of the eyelids can be obtained with placement of a gold weight
in the upper lid. This may be done externally or fixed inside the upper lid by a
surgical procedure. The weight acts by gravity to help close the eyelids in the
relaxed state. This procedure is only useful in certain cases.
Brow ptosis
correction
-There are several different procedures to correct the position of the drooping
eyebrow. Some are done directly over the eyebrow while others may be carried out
via the forehead or the scalp. This is often necessary for cosmetic reasons
while in some situations it is necessary to improve the field of vision.
Are there any risks or side effects?
·
There may be bruising around the eye
·
There is a small risk of infection of the lid or eye
·
There is a possibility of recurrence or under correction of the eyelid, which
may require further surgery
·
You
may end up with a scar
Special Problems
Neurotrophic
Keratitis
can accompany facial paralysis when surgery is performed for head and neck
lesions. Patients have diminished sensation of the cornea (coloured part of the
eye) and cannot feel dryness or foreign bodies which can rub on the corneal
surface. In this situation there is a greater incidence of corneal ulceration.
Crocodile Tears
– This is a rare symptom of facial nerve paralysis. This happens due to abnormal
connections between the tear production mechanism and chewing muscles, during
the recovery phase of the facial nerve paralysis. As a result, one may
experience copious and embarrassing watering of the eye while eating. This can
be successfully managed using repeated injections of the botulinum toxin.
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