SYNDROMES & DIAGNOSTIC TEST ASSOCIATED WITH FACIAL NERVE

SYNDROME ASSOCIATED WITH FACIAL PALSY:
  • Ramsay Hunt syndrome is also known as herpes zoster oticus or herpes zoster cephalicus. 
  1. This syndrome is associated with facial palsy, sensorineural hearing loss, dizziness and herpetic eruptions and is caused by reactivation of a neurotrophic virus, the herpes zoster virus in the geniculate ganglion.
  2. Lower facial nerve palsy and rash on the outer ear and inner ear canal.
  3. The prognosis of facial involvement in this condition is worse than in Bell’s Palsy.
  4. Inability to close left eyelid, drooping of ipsilateral angle of mouth and inability to taste food. history of discharge from his left ear. 
  • Melkerson Rosenthal syndrome consists of unilateral or bilateral facial paralysis, chronic swelling of the face (especially the lips), and lingua plicata (scrotal tongue) recurrent and eventually permanent facial (particularly labial) edema; and, less constantly, plication of the tongue. Its cause is unknown.
  • Marcus Gunn jaw-winking syndrome is usually an acquired condition following abnormal regeneration of the facial nerve. There is associated movement between the orbicularis oculi and the muscles around the mouth, often resulting in elevation of the upper eyelid when the mouth is open and ptosis when the mouth is closed.
  • Frey’s syndrome or gustatory sweating characterized by sweating, flushing, a sense of warmth, and occasional mild pain over an area of skin of the face while eating foods that produce a strong salivary stimulus. The disorder usually involves the area of skin innervated by auriculotemporal nerve.Frey's syndrome is caused by Post traumatic nerve fibres of facial nerve with parasympathetic of auriculotemporal nerve.
PREOPERATIVE EVALUATION:
  • History : Focusing on the onset and duration of weakness.
  • Complete physical exam of the head and neck:
  1. The muscles of facial expression(specially Orbicularis oris) are evaluated for symmetry and function—both statically and dynamically.
  2. Deviation of angle of mouth towards opposite side shows facial nerve palsy occurring due to lesion at the outlet of stylomastoid.
  • Schirmer's Test :Determines whether the eye produces enough tears to keep it moist.
A negative (more than 10 mm of moisture on the filter paper in 5 minutes) test result is normal. Both eyes normally secrete the same amount of tears.
It is performed with the help of a 5 x 35 mm strip of Whatman-41 filter paper which is foldei 5 mm from one end and kept in the lower fornix at the junction of lateral one-third and medial two-thirds. The patient is asked to look up and not to blink or close the eyes.
How to read results of the Schirmer's test:
Normal which is >15 mm wetting of the paper after 5 minutes.
Mild which is 14-9 mm wetting of the paper after 5 minutes.
Moderate which is 8-4 mm wetting of the paper after 5 minutes
Severe which is
  • Electrical testing is performed to determine the physiological status of the facial nerve branches and the muscles of the face(EMG & ENG)
  • ELECTRONEUROGRAPHY (ENG)
  • Measure of the amount of intact axons relative to the healthy side .
  • Used to determine prognosis pre-operatively
  • Degeneration greater than 90% is correlated with a poor prognosis .
  • ELECTROMYOGRAPHY (EMG)
  • Electromyography is often used as an adjunct to ENOG
  • EMG can be used to identify false positive ENOG results
  • NERVE EXCITABILITY TEST (NET)
  • Determine prognosis for facial nerve recovery
  • A threshold difference of greater than 3.5 mAmps correlates with a poor prognosis. 
Exam Question
  • Facial Nerve stimulation during testing of nerve indicated by contraction of orbicularis oris muscle
  • Facial nerve involvement in herpes zoster is known as Ramsay hunt syndrome
  • Melkersson-Rosenthal syndrome consists of recurrent facial paralysis
  • Schirmer's test is done to assess the function of Facial nerve
  • Inability to close left eyelid, drooping of ipsilateral angle of mouth and inability to taste food. History of discharge from his left ear are the symptoms of facial nerve palsy after herpes zoster infection
  • Prognosis of Ramsay hunt syndrome is poor than Bell's palsy 
  • Deviation of angle of mouth towards opposite side shows facial nerve palsy occurring due to lesion at the outlet of stylomastoid.
  • Frey's syndrome is caused by Post traumatic nerve fibres of facial nerve with parasympathetic of auriculotemporal nerve

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