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FACIAL (VII) NERVE DISORDERS Anatomy Bell's palsy Congenital Differential diagnosis Facial nerve: Anatomy + 2 roots Motor Origin: From facial nucleus Muscle Projections Facial Stapedius Digastric & Stylohyoid Nervus intermedius (of Wrisberg) Sensory afferents Origin: Cell bodies in geniculate nucleus Projections Skin: To spinal nucleus of cranial nerve V Taste: To nucleus tractus solitarius Preganglionic parasympathetics Origin: Superior salivatory nucleus Ganglion innervation Submandibular Pterygopalatine Branches Greater & Lesser petrosal To: Pterygopalatine & Otic ganglia Parasympathetic Lacrimation & Salivation Nerve to stapedius muscle Origin: Tympanic canal Ends in: Inner ear Chorda tympani Joins lingual nerve Taste in anterior 2/3 of tongue Preganglionic Parasympathetic fibers To submandibular ganglion To sublingual & submaxillary salivary glands Sensory (Posterior) auricular branch Sensation Posterior external auditory canal Inferior ear pinna Some axons may arise from vagus (Arnold's nerve) Motor innervation Exits skull: Stylomastoid foramen Neck Stylohyoid muscle Digastric muscles Facial muscles (Facial expression): Branches Temporal Zygomatic Buccal Mandibular Cervical Facial nerve: Anatomy Diagram Neighboring nerves VI: VII nerve Internal genu around VI nucleus VIII: With VII nerve in internal acoustic canal EMG: Motor units vs Limbs Amplitude: Smaller Duration: Shorter Firing rate: Faster

From: Eichhorst

Bell's Palsy ⁸

Sir Charles Bell

Facial Paresis: Left

• Epidemiology
  • Lifetime prevalence: 6.4 to 20 per 1,000
  • Incidence: Increased with age
    • Overall: 0.2 to 0.5 per year per 1,000
    • Age 20: 0.1 per year per 1,000
    • Age 80: 0.6 per year per 1,000
  • Male = Female, or slight Female predominance
  • Increased incidence
    • Diabetes
    • Pregnant females: Especially in 3rd trimester ¹³
    • ? Covid-19: Before or after disease onset
  • Family history : 4%
• Pathogenesis
  • Evidence for herpes simplex type 1 infection
• Clinical Features
  • Onset
    • Paralysis: Progresses to maximal defecit over 3 to 72 hours
    • Pain (50%): Near mastoid process
    • Excess tearing (33%)
    • Other: Hyperacusis; Dysgeusia
  • Signs
    • Facial weakness
      • All branches of nerve: Upper & Lower
      • Unilateral
      • Degree: Partial (30%); Complete (70%)
      • Side: Right in 63%
    • Stapedius dysfunction (33%): Hyperacusis
    • Lacrimation: Mildly affected in some patients
    • Taste
      • No clinically significant changes in most patients
      • Gustatory testing
        • May be reduced unilaterally or bilaterally
        • Often more severely reduced on paretic side
    • Sensory loss ⁷
      • Mild or None
      • May be present on face or tongue: On side of paralysis
      • Possibly related to involvement of greater superficial petrosal nerve
  • Prognosis better
    • Disease features
      • Incomplete paralysis
      • Early improvement
      • Slow progression
      • Normal
        • Salivary flow
        • Taste
        • Hearing
    • Patient characteristics
      • Younger age
      • No history of prior Bell's palsy
    • Electrodiagnostic tests
      • Nerve excitability: Normal or CMAP decline < 90%
      • Electrogustometry: Normal
      • Blink reflex: Present
    • Early treatment (≤ 3 days)
  • Course
    

    Facial Paresis: Right Widened palpebral fissure

    • Improvement onset: 10 days to 2 months
    • Plateau: 6 weeks to 9 months
    • Residual signs
      • Synkinesis
        • Frequency: ~50%; May be reduced by corticosteroid treatment
        • May be treated with botulinum
        • Probably due to misregeneration of nerve
      • Face weakness: 30%
      • Contracture: 20%
      • Crocodile tears: 6%
      • Blepharospasm: May occur years after paralysis
    • Recurrence: 7%
      • Frequency of ipsilateral & contralateral side: Similar
      • Time after initial VII paralysis: Mean 10 years
      • 2nd recurrence: 1.3%; 15% of Recurrent group
      • Associations
        • Possibly more frequent: Diabetes; Family history +
        • No relation to degree of recovery of 1st episode
        • Ipsilateral recurrence: No clear relation to mass lesion (Neuroma)
  • Evaluation: Some patients
    • Chest X-ray
    • MR imaging: Especially in atypical cases with slow progression
    • Lumbar puncture
    • Lyme titers
    • Electrodiagnositic testing: In severe paresis to determine extent of injury
  • Variant: Bilateral simultaneous facial palsy ¹²
    • Frequency: 0.4% of Bells palsy
    • Onset in 2nd nerve: 1 to 6 days after 1st nerve paresis
    • Severity: Often severe bilaterally
    • Prognosis: Similar to unilateral Bell's palsy
    • Differential diagnosis: Infectious mononucleosis; Ramsay Hunt syndrome
• Treatment of Bell's palsy
  • Statistical degrees of benefit from drug treatment
    • Prednisone > Placebo
    • More benefit when treatment started within 3 days of onset
    • No benefit from treatment starting more than 10 days after onset
  • Corticosteroids
    • Use within one week of onset
    • Adults: Prednisone 80 mg qd x 5 days
    • Children: Prednisone 1 mg/kg/day
    • After initial dose: Taper off over 7 to 10 days
  • Anti- viral medications: No clear benefit ¹¹
    • Acyclovir ⁵
      • Adults
        • 2,000 mg per day (400 mg 5x/day) for 7 days
        • With varicella zoster 4,000 mg per day
      • Children: 80 mg/kg per day for 5 days
      • ? More effective in Ramsay-Hunt syndrome
    • Alternative anti-viral: Valacyclovir
  • Protect eye from exposure
  • ? Facial exercise
• Laboratory
  • CSF: Protein high in 30%; Cells in 10%
  • Calorics: Often reduced on affected side
  • CNS imaging (MRI with gadolinium)
    • Localization of lesion ⁹
      • Proximal facial (suprageniculate) segment: Intrameatal (Distal), Labyrinthine & Geniculate ganglion
      • Peripheral segment rarely involved
    • Indications
      • No improvement in facial paresis after 1 month
      • Hearing loss
      • Multiple cranial nerve deficits
      • Signs of limb paresis or sensory loss

• Unilateral VII weakness
  • Idiopathic: Bell's palsy
  • Sarcoid & other granulomatous disorders
  • Infection
    • Leprosy: Especially with paralysis of upper face
    • Otitis media
    • Lyme disease
      • Epidemiology: European, Children, Summer & Fall
    • HIV
    • Herpes Zoster (Ramsay Hunt syndrome)
  • Neoplasm & Masses
  • Trauma
  • Cardiofacial syndrome : Lower lip or complete facial palsy
  • Familial, Recurrent
    • Facial paresis
    • Facial & Cranial nerve palsies
  • CNS lesions: Weakness patterns ¹⁴
    • Most affected (Lower face): Lip opening; Centrifugal mouth movement
    • Less affected: Lip closure; Centripetal mouth movement; Upper face
    • Isolated lower face: 25%
    • Emotional palsy (Concurrent volitional impairment): Brainstem; Internal capsule; Basal ganglia
    • Anterior cerebral artery lesions: Eyelid closure
    • Middle cerebral artery lesions: Centrifugal lip movement
  
  
• Bilateral VII weakness
  • General
    • Definition: 2nd facial nerve paresis occuring within 30 days of 1st
    • Frequency: 0.3% to 2% of patients with facial paralysis
  • VII nerve lesions
    • Hereditary
      • Amyloidosis: Gelsolin
      • Melkersson syndrome
      • Möbius syndrome & Congenital facial paresis
      • An-α-lipoproteinemia (Tangier)
    • Infection
      • Leprosy
      • HIV infection: May occur before seroconversion
      • Lyme disease
    • Guillain Barré: Variant
  • Other peripheral causes
    • Motor neuron disorders
    • Myasthenia gravis
    • Myopathies
  
  
• Upper face VII weakness
  • Leprosy
  • Amyloidosis: Gelsolin
  • Möbius syndrome
  
  
• Central VII lesions
  • Pyramidal: Lower face paralysis with voluntary motion
  • Emotional ²: Face paralysis with emotion
    • Anatomy: Dorsolateral pons lesion
    • Disorders
      • Superior cerebellar artery infarction
        • Unilateral
        • With Deafness, Horner's, or Reduced Sweating
      • Extrapyramidal disorders
        • Bilateral
        • Parkinsonism
  
  
• Hemifacial spasm

Melkersson-Rosenthal syndrome

• Clinical
  • Onset
    • 5 to 70 years
    • Incomplete penetrance
  • Recurrent facial palsy
    • Unilateral or Bilateral
    • May include loss of taste
  • Edema: Facial, Lip & Eyelid; Non-pitting
    • External link: Image
  • Onset: < 16 years
  • Lingua plicata (Scrotal tongue)
• Laboratory
  • Eyelid pathology: Granulomatous lymphangitis

Möbius & Congenital facial syndromes

• General
  • Nosology: Moebius syndrome; Brainstem dysgenesis syndromes
  • Anatomy: Rhombencephalic maldevelopment
  • Definition: Congenital, nonprogressive facial weakness with limited abduction of one or both eyes
• Clinical
  • Onset: Congenital
  • Facial paresis
    • Unilateral or Bilateral
    • Upper > Lower
    • Congenital facial paresis: Types
      • Möbius syndrome 1 (MBS1): 13q12
      • Möbius syndrome : REV3L ; 6q21; Dominant, de novo
        • Mutations: Missense, Splice site, Stop; Heterozygous
      • Möbius syndrome : PLXND1 ; 3q22.1; Dominant, de novo
        • Mutations: Missense (N1895K; R1485P); Heterozygous
      • Hereditary congenital facial paresis (HCFP)
        • HCFP1: 3q21
        • HCFP2: 10q21
        • HCFP3: HOXB1; 17q21
        • Facial palsy, congenital, with Ptosis & Velopharyngeal dysfunction (FPVEPD): TUBB6; 18p11
      • Chromosome translocation: 1q22
      • Carey-Fineman-Ziter syndrome
  • Ophthalmoplegia
    • Common
    • Especially VI nerve: Inability to abduct past midline
    • Patterns
      • Bilateral: 90%
      • Abducens nerve palsy, isolated: 9%
      • Conjugate horizontal gaze paresis: 48%
      • Duane retraction syndrome: 34%
      • Congenital fibrosis of extraocular muscles: 9%
  • Bulbar
    • Palate and pharynx dysfunction: 56%
      • Dysarthria, nasal
      • Poor feeding
      • Chewing defects: Associated with malocclusion
      • Normal masticatory muscle function
    • Tongue weakness: Hypoglossal nerve involvement
      • Hypoplasia
      • Asymmetry
      • Limited range of motion
  • Brainstem: Other
    • Respiratory abnormalities: 19%; Early death
    • Sleep disorders: Rapid eye movement sleep behavior disorder ¹⁰
  • Motor disability, general: 88%
    • Poor coordination (83%)
    • Hypotonia: Congenital
  • Poland syndrome: Some patients
  • Malformations
    • Hands: Deformities
    • Legs: Hypoplasia
• Laboratory
  • EMG
    • Neurogenic: Normal or low amplitude motor unit potentials
    • No spontaneous activity
    • Recruitment: Reduced
  • Facial NCV: Slow; Long latency in 40%
  • Blink response: Absent bilaterally in 60%

• Sporadic
  • Associated with toxic exposure
    • Attempted abortion using misoprostol: Odds ratio = 38
    • Cocaine
• MBS1
    ● Chromosome 13q12.2-q13; Dominant
  • Clinical: See general features
    • Congenital facial diplegia; ± Asymmetric
    • Ophthalmoplegia, esp VI nerve
    • Mental retardation
    • ± Peripheral neuropathy
    • Skeletal: Arthrogryposis; Orofacial malformations; Rib defects
    • Muscle aplasia
    • Respiratory failure: Central; Associated with tegmental brainstem calcification
    • Hypogonadotropic hypogonadism
  • Pathology: Aplasia or hypoplasia of cranial nerves & nuclei
  
  
• Hereditary congenital facial paresis 1 (HCPF1; MBS2) ¹⁶
    ● GATA-binding protein 2 (GATA2) ; Chromosome 3q21.3; Dominant or de novo
  • Nosology: MBS2; Isolated congenital facial paresis
  • Epidemiology
    • > 37 patients
    • > 90% of Dominant Congenital facial palsy
  • Genetics
    • Mutations
      • Location: Neuron specific regulatory region
        • Region includes 2 enhancers & 1 silencer
      • Types: Heterozygous duplications; Noncoding single-nucleotide variants (SNV)
      • SNV mutations: May cause milder phenotype
    • Allelic disorders
      • Emberger syndrome
      • Immunodeficiency 21
      • Leukemia, acute myeloid, susceptibility to
      • Myelodysplastic syndrome, susceptibility to
      • Hemophagocytic Lymphohistiocytosis
  • GATA2 protein
    • Transcription factor
    • Necessary to differentiate rhombomere 4 motor neurons to inner-ear efferent neurons
    • Downstream effector: GATA3
  • Clinical
    • Onset: Congenital
    • Facial weakness
      • Asymmetric
      • Unequal involvement of the 3 branches of the facial nerve
      • Bilateral (80%)
      • Upper ≥ Lower (90%)
    • No ophthalmoplegia
  • Pathology
    • Facial nucleus: Reduced numbers of neurons
    • Facial nerve: Small
    • Rhombencephalon & corticospinal tracts: Normal
  • Laboratory
    • MRI: Facial nerves thin or not visible
    • NCV: Facial amplitudes low or normal
    • Acoustic stapedial reflex thresholds: Elevated or Absent
    • Auditory testing: Normal
  
  
• Hereditary congenital facial paresis 2 (HCPF2; MBS3) ¹
    ● Chromosome 10q21.3-q22.1; Dominant
  • Nosology: MBS3; Congenital facial paresis with variable hearing loss
  • Genetics: Variable penetrance
  • Clinical
    • Facial weakness: Unilateral or Bilateral
    • Hearing loss: Congenital deafness, or Progressive hearing loss with age
    • Ophthalmoplegia
  
  
• Congenital facial palsy with Sensorineural hearing loss, Dysmorphic features & Strabismus (HCFP3) ¹⁵
    ● Homeobox B1 (HOXB1) ; Chromosome 17q21.32; Recessive
  • Epidemiology: 6 families
  • Mutations: Homozygous; Missense & Stop; Arg207Cys, Arg230Trp, c.296_302del (p.Y99Wfs*20), pTyr22*
  • HOXB1 protein
    • Homeodomain-containing transcription factors: Confer specificity of spatial-temporal patterning
    • Expressed in early development in spinal cord & brain
    • Role in the formation of rhombomere 4
    • Controls anteroposterior identity of vestibular projection neurons
  • Clinical
    • Onset: Congenital
    • Facial nerve
      • Palsy: Bilateral weakness
      • Sparing of stapedial muscle
      • Sensory component: Normal
      • Feeding difficulty
    • Hearing loss
      • Sensorineural
      • Contralateral vestibuloacoustic (CVA) neurons: Abnormal in Hoxb1^-/- mice
    • Strabismus: Esotropia; Full ocular motility
    • Dysmorphic features
      • Midface retrusion
      • Nasal tip: Upturned
      • Ears: Low-set & posteriorly rotated
      • Micrognathia
  • Laboratory
    • MRI
      • Facial nerves absent
      • Cochlea: Bilateral abnormal tapering of basal turn
    • Cochlear function: Abnormal
  
  
• Facial palsy, congenital, with Ptosis & Velopharyngeal dysfunction (FPVEPD)
    ● Tubulin, Beta-6; (TUBB6) ; Chromosome 18p11.21; Dominant
  • Epidemiology: 5 generation family
  • Genetics
    • Mutation: Heterozygous; Phe394Ser
  • TUBB6 protein
    • β-Tubulin
  • Clinical
    • Onset age: Congenital
    • Eyes
      • Ptosis: Bilateral
      • Eye movements
        • Horizontal: Normal
        • Upgaze: Mildly reduced in some patients
    • Face: Weakness, bilateral
    • Pharynx
      • Uvula: Wide
      • Gag reflex: Reduced
      • Rhinophonia aperta: With speech articulation defects
    • Course: Non-progressive
    • Intrafamilial variability
  • Laboratory
    • Brain MRI: Normal
  
  
• Facial diplegia, Chromosome translocation
    ● Chromosome 1q22
  
  • Genetics
    • Mutation
      • Reciprocal translocation between chromosomes 1 & 11: t(1;11)(p22;p13)
      • Reciprocal translocation between chromosomes 1 & 2: t(1;2)(p22.3;q21.1)
    • Mutation often on paternally derived chromosome
  • Clinical
    • Facial diplegia
    • Ptosis
    • Other cranial nerves involved in some patients: III, VI, VIII
    • Facial deformities: Anteverted nostrils, Malformed and low-set ears
    • Developmental delay: Mild
    • Poland syndrome: 1 patient
    • Congenital heart disease
      • Atrial septal defects +
      • Similar genetic changes in cardiofacial syndrome
  
  
• Carey-Fineman-Ziter syndrome
    ● Recessive

Facial Nerve Trauma & Tumors

• Trauma
  • Petrous bone fracture
  • Surgery: Middle ear; Mastoidectomy; Parotid gland
  
  
• Tumors & Masses ⁶
  • Tumor types
    • Neuroma/Neurinoma/Schwannoma: Most common
    • Meningioma
    • Hemangioma: Produce defects even with small size
    • Cholesteatoma
    • Parotid gland
    • Metastasis
    • Carcinomatous meningitis
    • Paget: Osteopetrosis
  • Tumor location
    • Most common: Geniculate ganglion & Tympanic region
    • Tumors along multiple segments of VII nerve common
    • Rare: Middle cranial fossa
  • Signs
    • Facial weakness: 82%
    • Course: Weakness progressive
      • Usually > 1 year
      • Range: Over 2 to 120 months
    • Hearing loss: Some patients; Conductive, sensorineural or mixed
    • Tumor visible by otoscopy
    • Other: Some tumors found incidentally
  • Diagnosis: MRI from brainstem to parotid
  • Treatment
    • Surgery
    • Residual or increased facial paresis common: More deficit after 1 year of symptoms
    • Best prognosis after removal of hemangioma

Hemifacial Spasm Onset Adults Typically 5th or 6th decade Younger patients: Rule out brainstem disease, MS Location: Orbicularis oculi muscle More common in women Contraction pattern Synchronous contraction of facial nerve innervated muscles Paroxysmal Involuntary Duration: Up to 1 minute May persist during sleep Usually unilateral Weakness: Unusual Triggers: Aggravating factors Emotion Fatigue Causes Recovery from Bell's palsy Associated with synkinesis & contracture Dolichoectatic brainstem artery Frequency: 30% Mechanism: Pressure on VII root entry zone Vessels: PICA; AICA; Vertebral Brainstem disease Idiopathic Course: Usually permanent without treatment Electrophysiology Brief bursts of action potentials High frequency (150-400 Hz) Normal motor units Variable rhythm & amplitude Lateral spread response 3 Stimulation: Facial nerve branch Response: In muscles not normally innervated by branch   Related to cross transmission of facial nerve fibers Location: Probably at site of compression Treatment Botulinum toxin Microvascular decompression of VII nerve Morbidity & Mortality 5% Anticonvulsants Bright 1831

Barker T2 image: Brainstem & Cerebellum MRA: AP view Dolichoectasia of vertebral arteries Deviation to right (Arrows) Patient syndrome: R hemifacial spasm