facial palsy Flashcards
cranial nerve 7
facial nerve
facial expression
the facial nerve
The larger Motor component, which supplies all the muscles of facial expression.
The smaller Nervus Intermedius (intermediate nerve)
composed of:
Sensory portion carrying afferent taste fibres from the anterior 2/3 of the tongue Parasympathetic portion carrying visceral efferent fibres to the lacrimal, submaxillary and sublingual glands
facial nerve anatomy
Pons: motor nucleus of CN VII.
Lower pons: nucleus salivatorius (nervus intermedius)
The facial nerve, nervus intermedius and vestibulocochlear (CN VIII) nerves exit the brainstem at the
cerebellopontine angle.
They enter the petrous temporal bone via the facial canal in the Internal Auditory Meatus
Cell bodies of the nervus intermedius lie in the geniculate ganglion in the facial canal
As it runs through the IAM, the following branches are given off:
Nerve supply to lacrimal glands (NI)
Nerve to the stapedius muscle (FN)
The Chorda tympani branch (NI) - joins the lingual nerve carrying taste fibres to the anterior 2/3 of the tongue, and parasympathetic fibres to the submandibular and sublingual salivary glands.
Then, on exiting IAM:
Branches to posterior auricular muscle, posterior belly of digastric muscle, and stylohyoid muscle
(FN)
Sensory branch: posterior auricular nerve (FN)
upon exiting the IAM, nerve passes through the parotid gland
branches of facial nerve
Temporal branch to the forehead supplies the muscles of surprise, frown and gentle closure of the eyelid.
Zygomatic branch supplies the muscles of eye closure.
Buccal branch raises the corner of the mouth
and upper lip for a smile.
Mandibular branch produces a simple smile and supplies all the muscles of the chin helping to turn the corner of the mouth down.
Cervical branch supplies the superficial
muscles of the neck as far as the collar bone.
causes of facial palsy
viral infection herpes simples herpes zoster mealses mumps
physical direct trauma skull trauma cerebellopontine angle tumour parotid gland tumour injury at birth
other causes UMN lesions MS stroke Guillain barre syndrome HIV dental abscess otitis media pregnancy
degree of injury PNS
injury neuropraxia compression causing conduction loss no structual change <6 weeks no degeneration regen - not required recovery - complete
axonnotmesis axons degenerate leaving only shcwann cell layer intact duration depends on length of nerve degen - yes - axons regen - begins in 3-8 weeks of injury rate = 1mm / day
recovery - potentially complete by nerve is thin and frail, prone to synkinesis
neurotmesis - complete destruction or severing of axons - schwann cells and nerve sheath duration depends on success of surgery degen - yes, entire nerve
regen - not possible
recovery - surgery repair
Causes of facial palsy
1. bells palsy
Most common cause of facial weakness
Acute unilateral inflammation of the facial nerve within the facial canal
Incidence: 20-25/100,000
M:F 1:1
Signs and Symptoms Sudden (<72h) painless unilateral facial muscle dysfunction ± some or all of the following: Fever Tinnitus Mild hearing deficit or hyperacusis Altered or absent taste of the anterior 2/3 of the tongue 20% report numbness of ear or face
bell’s palsy management
Consensus statement of De Almeida et al (2014)
Detailed assessment, including subjective history
Exclude other causes
No role for electrophysiology, diagnostic imaging or other investigations
Oral steroids within 72h of onset
Eye protection
Physiotherapy: can prescribe exercise, no role for electrical stimulation
Patient Follow-up: Clinicians should reassess or refer to a facial nerve specialist those Bell ‘s palsy patients with (1) new or worsening neurologic findings at any point, (2) ocular symptoms developing at any point, or (3) incomplete facial recovery 3 months after initial symptom onset (Recommendation)
bell’s palsy prognosis
Full recovery within 6 weeks: 86% (complete paralysis) 90% (incomplete paralysis) If paralysis persists >6 weeks, this suggests axonal degeneration Poorer prognosis if: Diabetes Mellitus > 60 years Pain Disturbance of taste, hyperacusis, dry eyes
cause facial palsy
2. vestibular scwannoma
Benign tumour (Grade 1), of the vestibulocochlear nerve, usually at the cerebellopontine angle
Symptoms: deafness in one ear, pain behind the ear, tinnitus, dizziness,
vertigo-like symptoms
Usually managed conservatively (“watch and wait”). Surgical intervention only if:
Balance disturbance – ataxia
Trigeminal symptoms
Progressive facial weakness
Scans show increase in size >2.5 or 3cm
Surgery = retrosigmoid craniotomy and excision
Risk of intra-operative damage to the facial nerve
Damage usually due to swelling rather than physical injury
Facial nerve electrically stimulated intra-operatively: should conduct with 0.1mV (check op notes)
About half of patients will have persistent weakness at one month post op
physio Rx for facial palsy
Ax care of the eye functional advice exercise therapy facial massage taping trophic stimulation
subjective Ax
Database: As well as usual headings, determine: Diagnosis (if known) Management to date (if any) MDT (neurologist, otolaryngologist / ENT, neurosurgeon) Medications: steroids
Sudden onset, painless? → Bell’s
Pain prior to sudden onset? → Stronger viral infection
Preceded by inner ear symptoms? → Ramsay Hunt syndrome
Trauma? Blunt or sharp (knife) injury → plastic surgery involvement
Slow onset with no obvious cause → needs investigation (neurologist / ENT)
Central (upper face preserved) → needs investigation (neurologist) (unless cause known)
Ask about these functional problems:
Food or drink falling from the mouth
Drooling while eating or drinking
Biting the inside of the cheek
Dryness of the affected eye
Difficulty keeping eye closed for protection
Excessive tears
Slurred speech
Difficulty keeping eye open during speaking / drinking
Spasms around the eye
Screen for neurological flags:
Vestibular: hearing loss, dizziness / vertigo, falls, nausea and vomiting
Cerebellar: dexterity changes, poor coordination
UMNL: Motor or sensory symptoms, abnormal tone / spasms
objective nerve
Facial symmetry at rest
Active range of movement: test five branches of the facial nerve
Temporal: Raise eyebrows Zygomatic: Gentle eye closure Buccal: Snarl (“show top teeth”) Mandibular: Smile
Cervical: Depress mouth (“show bottom teeth”), pucker lips
Observe excursion compared to unaffected side
Observe for synkinesis
Outcome measures: Sunnybrook Facial Grading Scale, House-Brackmann score
objective assessment
Optional components:
Upper motor neuron / central problem → Full neurological exam of all four limbs
(T/P/C/S/R)
Potential vestibular involvement (dizziness) → Vestibular assessment, balance assessment
Potential cerebellar involvement (vestibular schwannoma, or other CP angle tumour)
→ cerebellar signs, balance assessment
eye care and management
Paralysis of orbicularis oculi → no blink reflex, no active eye closure Crocodile tears
Dry eye
Ophthalmology
Conservative management:
Consider lubricating drops and ointments
Give advice re glasses or sunglasses
Consider taping (night), patches, moisture eye chambers
Surgical intervention: eyelid weights, tarrsorophy
maintain nasal ventilation
Loss of the nasalis and dilator naris muscles, combined with low-toned mid-face tissues, can result in nasal valve collapse and nasal obstruction
Re-educate nasal breathing
Use nasal strips
stretch/ massage
Superficial soft tissue massage and stretch begins with focus on musculature involved in movement of the mid-face and progresses to include other facial musculature
exercise therapy
Aims
To prevent adaptive muscle length changes
To re-educate muscle activity beginning with active assisted movements
To prevent onset of abnormal movements or synkinesis
To improve sensory input to the face
Remember the characteristics of facial muscles:
Small cross sectional area
Slow oxidative fibres
Not very fatigable
Attach to dermis of skin and fascia, not to bone
Small motor units
Educate to avoid mass movements and avoid overuse of the uninvolved side, such as by forming a wide smile or chewing gum
Educate to avoid overuse of the affected side
Treatment position determined by muscle activity: supine or sitting
Active-assisted if patient can initiate slight movement in any or all regions of the face (scores of >2 on the voluntary movement section of the FGS)
Passive excursion using fingertips if there is no movement initiation
Mime therapy may be beneficial (Beurskens et al, 2006)
The goal is to perform small, slow and controlled facial movements with emphasis on symmetry between the two sides of the face Systematic review (Pereira 2011): facial exercises improve outcomes relating to function
mirror feedback
Due to the lack of muscle spindles in the facial musculature, there is minimal proprioceptive input, therefore visual feedback is imperative for increasing awareness and performance of graded movements within the muscles
examples of exercises
Eyebrow raise Gentle eye closure Closed-mouth smile Open-mouth smile Frown / eyebrow furrow Snarl (show top teeth) Pucker / kiss / Blow Cheek puff Whistle Low load = normal movement, 10-20 reps, 2-3 times daily
synkinesis
Synkinesis is an abnormal movement of muscles of facial expression occurring simultaneously with the voluntary movement of other muscles of facial expression
Synkinesis is caused by the misdirection of young thin fibres in a regenerating facial nerve
Mechanisms:
Imperfect regeneration – multiple axonal sprouting
One axon innervating multiple endoneurial tubes
Learned movement patterns – poor patterns during exercise, lack of selective movement
Management:
Motor learning approach – correct patterns, deliberate focused practice, at least twice a day, multiple repetitions
Very challenging for patients – slow progress, intense concentration
relaxation
Meditation using guided visual imagery, focuses on teaching patients how to
release the tension in the synkinetic musculature
Verbal cues to help minimize synkinesis – ‘drain the tension around your eye’, for ocular synkinesis and ‘deflate the fully inflated balloon in your cheek’, for mid-facial synkinesis felt during closing of the eyes.
Frequency for relaxation techniques is 1 or 2 times per day
trophic electrical stimulation
“Trophic” refers to nutritional status of a muscle. Trophism = feeding, developing,
growth, metabolism, ability to self repair
Injury to peripheral nerve manifests in two ways: Loss of muscle contraction
Loss of nutrition via blood flow
Trophic stimulation aims to stimulate blood flow
Uses low frequency, unevenly spaced, low intensity electrical impulses – insufficient for contraction
What’s the evidence for electrical stimulation?
Original study (Farragher 1987) – crossover design – improvements with stimulation
Cochrane review 2011 (Teixeira et al): no benefit compared to placebo (one low- quality study showed worse outcomes in stimulation group)
No difference in incidence of synkinesis
RCT (Tuncay, 2015): “The addition of 3 wks of daily electrical stimulation shortly after facial palsy onset (4 wks), improved functional facial movements and electrophysiologic outcome measures at the 3-mo follow-up in patients with Bell palsy.”
