CN VII - Facial Nerve Flashcards
A patient is being managed for Bell’s Palsy. What advice would you give the patient as part of your conservative management?
!!!Eye care. Protect eye with lubricant as well as eye protection at night as they have trouble closing eyes
Advice:
Oral hygeine: Ensure that all food is cleared after meals with regular oral care and rinsing
Speech: Support weak cheek with hand to aid in speech and swallowing.
Massage BOTH sides of face to aid in recovery
Taste changes may be expected.
You walk in to clock in for work and you see two patients sitting in the waiting room. These are their images. Diagnose each of them.
Explain, as best you can
Upper motor neuron lesions spare the forehead due to the bilateral innervation of the upper facial muscles from both hemispheres of the brain. This results in the preservation of some voluntary movement in the forehead muscles despite the contralateral facial weakness. Lower motor neuron lesions affect the facial nerve or its nucleus directly, leading to ipsilateral facial weakness including the forehead, as all facial muscles on that side are innervated by the damaged nerve, resulting in more profound paralysis.
Explain the trajectory of the facial nerve with respect to the ear.
LIST the main functions of the facial nerve?
When assessing for symmetry, you typically ask the patient to smile. If you have a patient with a degree of facial nerve paralysis, how does the onset of its paralysis affect treatment options.
Initially runs in the Internal Acoustic/Auditory Meatus (IAM), close to the inner ear. It then runs along the medial wall of the middle ear, just above the stapes footplate/oval window, and just posterior to the EAM before emerging from the stylomastoid foramen where it splits into its branches and bisects the parotid gland into the lymph-node-rich superficial and deep lobe
Hyperacusis, Tasting Ant 2/3 (corda tympani), Motor - Muscles of the face except muscles of mastication -CNV), Sensory - Ramsay Hunt Area (Cavum Concha of pinna), Lacrimal glands, submandibular, and sublingual salivary (only bisects the parotid gland (CNIX), Stapes
If the paralysis occurred at the time of insult, it means the fracture, for example, is causing the damage => Surgical indication
If the paralysis occurred days after => Oedema/swelling/inflammation/mass effect => role of steroids (unless blead or tumour of course although they may present that way)
A patient presents to OPD with obvious full right-sided unilateral facial weakness without sparing the forehead when smiling. What tool would you use to assess the patient?
This only applies to LMN lesions and not UMN hence why forehead isnt spared
We use the House-Brackmann Scale:
I - Normal!
II - Slight Weakness
III - Obvious Weakness but can close eyes with effort!
IV - Cannot close eye!
V - Slight movement only
VI - No movement!
What is the most common cause of facial nerve paresis?
Idiopathic/Bell’s Palsy
List the causes of Facial Nerve Palsy
Idiopathic: Bell’s Palsy
Infectious: Viral (Herpes Zoster Otica/Ramsay Hunt), Bacterial (Necrotizing AOE, AOM, Cholesteatoma, Lyme’s Disease)
Trauma: Temporal Bone fracture, !Iatrogenic during ear/parotid surgery
Neoplastic: Parotid!, Vestibular Schwannoma/Acoustic Neuroma, facial neuroma
Congenital: Mobius Syndrome
Other: Melkersson Rosenthal Syndrome (rare)
Why would you assess hearing in a patient presenting with facial nerve palsy?
1) CN VII innervates stapes => conductive hearing loss
2) CN VII runs close to CN VIII => something like a tumour or bacterial infection affecting one may affect the other
What is your general workup for a patient presenting with facial palsy?
What is your general approach to management in any case?
Full detailed hx and examination (neurological, CN, ENT incl. otoscopy)
Pure Tone Audiometry
If no obvious cause 100% (e.g. tumour)
Conservative: !!!!Eye Protection,dentition, !!!Speech and language therapy, Dietitian referral
Steroids
Antiviral - Acyclovir
Define Bell’s Palsy
How would you diagnose Bell’s Palsy?
How will you manage this patient?
Bell’s Palsy is the idiopathic!! acute unilateral facial nerve paresis or paralysis with onset of <72 hours! but gradual
It is a diagnosis of exclusion but is the most common (70%)
Complete spontaneous recovery in over 90% of cases. Tx is general Eye protection + steroids + Acyclovir (why? incase ramsay hunt)
What is the most common infectious cause of facial nerve paresis?
Give other organisms that may cause this.
What is the common presentation of a patient presenting with the most common cause?
How would you manage this patient?
Herpes Zoster Otica reactivation/Ramsay Hunt Syndrome
P.Aeuroginosa (Necrotizing AOE or CSOM), Staph, strep (Necrotizing AOE), S.Pneumoniae, H. Influenzae, M.Catarrhalis (AOM,cholesteatoma) (Honour’s Question for sure)
Presentation: LMN facial nerve paresis, Severe Neuralgia!!, Vesicles in Ramsay hunt area!!, SNHL!!
Tx: Eye protection + steroids + Acyclovir + !Analgesia
Herpes Zoster Otica causes Ramsay Hunt Syndrome in facial nerve paresis due to its reactivation. Where is this virus typically latent in?
Geniculate Ganglion
How would trauma lead to facial nerve paresis?
Either direct trauma to the temporal bone and hence affecting area where it passes or Iatrogenic during surgery in area.
In both cases, it would be bending or stretching more often than cutting or oedema from swelling or mass effect from damage to surrounding tissue
What procedures commonly pose a risk to the facial nerve iatrogenically?
Parotidectomy!!, Mastoidectomy!!, Vestibular schwannoma surgery
What possible exam findings are you likely to find in a patient presenting to the ED after suffering a blow to the head.
Temporal bone fracture => effect to
Area: Battle’s Sign (impressive!)
Ear: Otalgia, discharge, infection, fracture, Conductive/sensorineural HL, tinnitus, vertigo, nausea, vomiting
Facial nerve: Taste, lacrimal, conductive hearing loss (stapes), Facial paresis!
Brain: Tegmen break or temporal bone fracture leading to hematoma => altered GCS, hemorrhage, death….
you get the idea
