Facial nerve disorder Flashcards
what is somatic motor?
Innervation of skeletal muscles
what is visceral motor
Innervation of smooth muscles
what is Visceral sensory
Sensation from the viscera (includes taste and smell as they are associated with the digestive tract)
what is somatic sensory
Sensation from sensory organs, skin, skeletal muscles, and connective tissue
where does somatic motor inervate?
1) Muscles of facial expression
»>Example: Furrowing of the forehead, raising the eyebrow; pursing lips; closing eyes
2)Postauricular muscle
Responsible for PAM-post auricular muscle reflex
3)Stapedius muscle (responsible for the middle ear acoustic reflex)
where does Visceral motor innervation
Lacrimal (tear ducts) and salivary glands (submandibular and sublingual)
where does visceral sensory innervate ?
Taste in anterior 2/3 of the tongue (chorda tympani nerve)
where does somatic sensory innervation
Posterior EAC, concha, ear lobe, and deep parts of the face
cn 7 is what type of nerve ?
its a mixed nerve
where does cn 7 come from
the 2nd pharyngeal arch
where does the facial nerve originate from?
From its origin in the facial motor nucleus in the anterior pons
facial nerve are inserted in what?
insertion in the muscles of facial expression and the stapedius muscle
where does the intracranial segment comes from?
from the facial motor nucleus in the anterior pons
where does the intracranial segment exit from?
Exists the brainstem at the pontomedullary junction
where does the intracranial segment run through?
Courses through the cerebellopontine angle (CPA) to enter the internal auditory canal (IAC) or meatus
where is a common site for facial nerve to getting trapped
the fallopian canal
where does the intratemporal portion run thru?
-its part of the labyrinthine
Passes through narrowest part of the fallopian canal (bony canal in the temporal bone)
what is the most common pathology associated with intratemporal portion
temporal bone fractures & Bell’s palsy
what does the tympanic segment form?
It forms the superior aspect of the oval window niche
what is the site of lesion in tympanic segment?
The facial nerve is readily injured here in pathologic processes and during ME surgery
what does mastoid segment show? in term of its branching pattern
It shows variable branching patterns in the face
-its all over the place
what about the way cn 7 travels makes it vulnerable to
The course of the facial nerve makes it vulnerable to many neoplastic, traumatic, and infectious conditions.
what is osteopetrosis?
The AD genetic condition (also called Albers-SchÖnberg Disease) is present at birth with varying severity and is a milder form than the AR condition, which is more severe
how do the bones look like in osteopetrosis?
It is a bony dysplasia; the bones harden and become denser
What does osteopetrosis do in terms bone ?
Causes multiple cranial neuropathies because of bony obliteration of neural foramina with entrapment and compression of cranial nerves
what other cn can be involved with osteopetrosis?
CN II, V, VII, VIII
-Congenital facial paralysis
-Vision (even blindness) and hearing loss (even deafness) are common
what is the treatment of osteopetrosis?
-Symptomatic
-Facial nerve decompression if nerve entrapment and associated facial dysfunction
what is mobius syndrome ?
Rare congenital disorder associated with hypoplasia of 6th (Abducens – moves the eye laterally) and 7th (Facial) cranial nerve nuclei
what can cause the mobius syndrome in the utero
Exposure in utero to teratogens such as :
1)Cocaine
2)Ergotamine
>Alkaloid used as a vasoconstrictor to treat migraine, induce childbirth, and prevent post-partum hemorrhage
3)Misoprostol (synthetic prostaglandin E1)
>Vasodilator used to prevent stomach ulcers & sometimes used as a treatment for tinnitus
what are signs/symptoms of mobius syndrome?
-Congenital facial diplegia (bilateral facial paralysis)
-Associated CN VI unilateral or bilateral paralysis
-Other cranial nerve deficits
-Deformities of extremities
-Musculoskeletal deformities
Intellectual disability
what are treatment of mobius
-Ophthalmologic consultation
-Nerve reconstructive surgery
what is the diagnosis of bells palsy ?
-Onset of partial/total unilateral facial paralysis during a 48-hour period
-Fever and neck stiffness at the onset
-No hearing loss or vertigo
-No other cranial neuropathy
-Normal head and neck examination
-Drying of eye due to decreased eye closure and lack of lacrimation
-Rare cases of recurrence
-Some spontaneous recovery should be noted within 3 to 6 months in all patients
what are the causes of bells palsy
Idiopathic (most common - diagnosis of exclusion)
Herpes simplex virus (main infectious agent)
what are the time period of diagnosis for bells palsy?
-within 3 to 6 months of onset of paralysis
-Audiometric evaluation
-Testing for HIV and Lyme disease, if appropriate
what test look normal in bells palsy
-Otoscopy – normal
-Pure-tone audiometry – hearing loss is rare
-Immittance audiometry - Normal tympanogram
how do reflexes look like in bells palsy ?
-Abnormal ARTS due to a lesion proximal to the stapedius nerve
-Presence of ARTs indicates lesion distal to the stapedius nerve
what are treatment of bells palsy ?
-Decompression of the nerve is indicated when > 90% degeneration occurs within 2 weeks of onset
»>Decompression involves relieving pressure on the nerve possibly by removing part of the surrounding bone
-Steroids indicated early in the course of the disease
-Acyclovir (antiviral) with steroids (inconsistent data re: benefits)
-Eye care to prevent permanent damage due to dryness of eye
what is the differential diagnosis for bells palsy?
-CPA or skull-based tumors
-Vestibular schwannoma
-Otitis media
-Parotid gland tumors
in bells palsy Good prognosis for recovery of function includes?
1)Younger patients
2)Partial paralysis and recovery of function within 2 months
3)Intact ARTs (lesion distal to stapedius nerve)
»>Lesion in the mastoid or extratemporal segment of the facial nerve
4)Electromyographic (EMG) evidence of voluntary activity
5)Electroneurography (ENoG) shows < 90% degeneration of electrically evoked muscle action potential after ~ two weeks of onset
what is the prognosis of bells palsy?
Majority of patients recover function within 3 to 6 months with no medical or surgical intervention except eye care
what are poor prognosis bells palsy
-Patients older than 65 years
-Greater than 90% nerve degeneration within the first two weeks as diagnosed with ENoG
-Diabetic patients
»»Who also show increased incidence/greater risk for Bell’s palsy because of a peripheral circulatory disorder that develops in the feeding vessels to the facial nerves
what is the most common injury in temporal fractures ?
Most common site of injury is adjacent to the geniculate ganglion
Hearing loss (conductive, mixed or SNHL) is common
what is the most common iatrogenic injury
-injury during surgical procedures
-The most common site of injury is the tympanic segment over the oval window; e.g., injury during otosclerosis and cholesteatoma surgery
what are lacerations
Facial nerve grafting after penetrating trauma to the nerve
what are treatments for malignant otitis externa
-Debridement of infected tissue
-Decompression of facial nerve when needed
-Antibiotics
facial paralysis is secondary to what ?
inflammatory ME disease
what causes acute suppurative otitis media
Caused by gram-positive bacteria and Haemophilus influenzae
what is the invasion of Acute suppurative otitis media
-Invasion into the facial canal through a dehiscence may evoke an inflammatory response with edema, compression, and ischemia resulting in facial weakness
»>Dehiscence is the erosion of or discontinuity in the bony structure of the facial canal, allowing for communication between the facial nerve and the middle ear cavity
what is the treatment for acute suppurative otitis media
-Myringotomy
-Appropriate antibiotics
-Trans-mastoid decompression if nerve degeneration is progressive
is facial paralysis a secondary symptom for chronic otitis media
yes!
-Paralysis can occur with or without cholesteatoma
what is the treatment of chronic otitis media
-This condition is an urgent indication for surgical intervention
-Tympano-mastoidectomy is appropriate for the chronic ear infection followed by decompression of involved facial nerve
-Removal of cholesteatoma, if present, adherent to the nerve
what are signs and symptoms of Herpes zoster oticus (Ramsay-Hunt Syndrome)
-Otalgia and severe pain
-Vesicular eruption on the concha and/or external canal and along the sensory distribution of 7th cranial nerve
-Facial paralysis that tends to be more severe
-Hearing loss
-Vertigo
-Higher frequency of complete degeneration of the facial nerve
what are the site of lesions in herpes?
-Labyrinthine segment of the facial nerve
-Can involve CNs V, IX, X, XI
-Herpes zoster cephalicus, which is rare and involves cervical dermatomes (skin areas)
what is the medication used for herpes
Acyclovir
what are symptoms seen in facial neuromas
1)facial weakness
2)HL
3)Tinnitus
4)Otorrhea
5)Ear canal mass
6)Otalgia
7)Vestibular symptoms
what are facial neuromas/schwannomas?
rare benign neoplasms of schwann cells
where are the majority of facial neuromas located ?
the tympanic area
if the tumor isn’t trapped in the IAC or CPA then what symptoms may we not see
, no facial symptoms maybe present
why might vestibular schwannomas be misdiagnosed
Misdiagnosis is then common especially with vestibular schwannoma because of the SNHL, which is often present in such cases – ARTs can be helpful for differential diagnosis
how might pure tones look like in facial neuroma ?
SNHL due to cochlear nerve compression by the tumor
how might tymps look like in facial neuromas
normal
how might reflexes look like in facial neuroma ?
-Abnormal ARTS due to a lesion proximal to the stapedius nerve
-Presence of ARTs indicates lesion distal to the stapedius nerve
how might Electroneurography (ENoG) look like in facial neuromas
ENoG can be normal in cases of VII N tumors located primarily in the CPA that may cause a hearing loss but do not affect facial function
what will determine if the tumor is acoustic or facial?
ABR
what is something important to remember with stapedius branch of facial nerve
-Abnormal ARTS if a lesion is proximal to the stapedius nerve
-ARTs present if a lesion is distal to the stapedius nerve
look at slide 39, it’s super important
look at slide 40
what are differential diagnosis for facial neuroma
1)Otitis media with conductive hearing loss
>With or without cholsteatoma
2)Cholesteatoma
>Requires prompt decompression of the VII N and resection of the cholestatoma
3)Glomus tumor (Paragangliommas – ME & jugular vein bulb)
4)Meningiomas
>Tumor of the meninges
5)Acoustic neuroma (vestibular schwannoma)
>Both VII and VIII nerve schwannomas have been reported in some cases of NF2
