Differential Diagnosis in Neurology

5.7. Cranial Nerve VII

Anatomy

• Medial placed motor division; lateral division nervus intermedius of Wrisberg
• Nervus intermedius of Wrisberg:
  • Efferent fibers arise from the superior salivatory nucleus
  • Preganglionic parasympathetic fibers to submandibular ganglion; post ganglion connections to the submandibular and the sublingual glands; pteropalatine ganglion with postganglionic connections to the palatal and nasal mucosa; lacrimal glands
  • Afferent fibers from: taste buds anterior 2/3 of tongue; mucous membranes of pharynx, nose and palate; external auditory meatus

Aspects of Anatomy of Peripheral Course of VII

• 23–24 mm from brainstem to internal auditory meatus
• At fundus of IAC: VII is anterior and superior to the vestibular nerve (7–8 mm)
• Labyrinthine segment: enters facial canal and passes above the labyrinth for 3–4 mm to reach the geniculate ganglion
• External genu: VII turns posteriorly and divides into three branches:
  • Petrosal nerve unites with deep petrosal nerve (origin from superior sympathetic ganglion and tympanic plexus of IX) to form the vidian nerve. The nerve ends in the pterygopalatine ganglion. At the pterygopalatine ganglion sensory branches of V join the vidian nerve, pass through the ganglion to supply the mucosa of the palate and nasal cavity
  • External petrosal nerve: joins the sympathetic plexus on the middle meningeal artery
  • Small branches join the petrosal nerve (from tympanic plexus of IX) to synapse in the otic ganglion
• Horizontal or tympanic segment:
  • Posterior and laterally for 12–13 mm adjacent to medial wall of the middle ear
• Vertical or mastoid segment:
  • Passes inferiorly for 10–14 mm at the posterior aspect of middle ear; gives off two branches:
    • Nerve to stapedius
    • Chorda tympani (travels within the facial canal to exit through aperture of the posterior wall of the middle ear; synapses with otic; and joins lingual branch of VIII
• Parotid segment: VII leaves the facial canal at the stylomastoid foramen. At exit point gives rise to: posterior auricular, digastric, and stylohyoid nerves (posterior auricular, occipital, posterior belly of the digastric and stylohyoid muscles)
• Anastomosis with:
  • IX and X
  • Auriculotemporal branch of V
  • Great auricular and lesser occipital branches of the cervical plexus
  • 15–20 mm through the parotid to terminate in muscles of facial expression: zygomatic, buccal (risorius), cervical branches, temporal, infraorbital branches

Blood Supply of VII

• Proximal: AICA branches level of the internal auditory canal
• Petrosal branch of middle meningeal artery
• Stylomastoid branch (from posterior auricular artery)

Localization of VIIth Nerve Lesions

• Ventral portion of nucleus of VII lower 2/3 of face has crossed supranuclear control; the dorsal portion of the nucleus bilateral supranuclear control
• Mimetic facial innervation: supranuclear origin in contralateral thalamus hypothalamus, basal ganglion and temporal lobe. Right sided predominance; these fiber do not descend through the internal capsule
• Nervus Intermedius of Wrisberg:
  • Sensory and parasympathetic division of the nerve:
  • Superior salivatory nucleus:
    • Preganglionic parasympathetic fibers to submaxillary ganglion (postganglionic fibers to submandibular and sublingual gland)
    • Lacrimal nucleus: controls lacrimation
    • Preganglionic parasympathetic fibers to pterygopalatine or sphenopalatine ganglion; postganglionic fibers to lacrimal, palatal and nasal glands
    • Sensory afferents in the nerve:
      • From the geniculate ganglion
      • Taste from anterior 2/3 of the tongue
      • Afferents from mucosa of the pharynx, nose, and palate
      • Skin of external auditory meatus, lateral pinna, mastoid
    • Gustatory afferents: synapse in nucleus of the tractus solitarius
    • Exteroceptive afferents: synapse in the nucleus of spinal tract of V
    • Proprioceptive afferents from the facial musculature: synapse mesencephalic trigeminal nucleus

Anatomy of Peripheral Segments

• Meatal (canal segment 7–8 mm)
  • Motor division super anterior surface of VIII (nervus intermedius between); close association with vestibular and cochlear portion of VIII
• Labyrinthine segment (3–4 mm):
  • Facial or fallopian canal (motor division and nervous intermedius)
  • Labyrinthine segment projects to the geniculate ganglion (contains sensory neurons of nervus intermedius)
  • Geniculate ganglion first branch: the greater superficial petrosal nerve (deep petrosal and sympathetics from tympanic plexus) form the vidian nerve that synapses with sphenopalatine or pterygopalatine ganglion; greater superficial petrosal nerve carries sensory fibers from the external auditory canal

Horizontal (Tympanic Segment) 12–13 mm

• Medial to horizontal semiauricular canal
• Chorda tympani: joins the lingual nerve; carries pre parasympathetic fibers that innervate submandibular and sublingual glands (submaxillary ganglion)
• Stylomastoid foramen:
  • Near the foramen:
    • Posterior auricular nerve (innervates the occipitalis, posterior auricular, transverse and oblique auricular muscles)
  • Digastric branch (posterior belly of the digastric)
  • Stylohyoid branch (stylohyoid muscles)

Parotid Gland (22–24 mm)

• Temporofacial
• Cervicofacial branches

Localization of VIIth Nerve Lesions by Location

• Supranuclear lesions
• Nuclear and fascicular (pontine)
• Cerebellar pontine angle (associated neurological deficits)
• Meatal segment:
  • Unilateral peripheral VII weakness
  • Decreased taste anterior 2/3 of the tongue (ipsilaterally)
  • Impaired lacrimation
  • Deafness
• Facial canal distal to meatal segment but proximal to stapedius branch:
  • Motor division and nerve of Wrisberg involved
  • No deafness
  • Ipsilateral VII weakness
  • If lesions are proximal to greater superficial petrosal nerve lacrimation is impaired
  • Geniculate ganglion involvement: eardrum pain
  • Decreased taste anterior 2/3 of tongue
  • Hyperacusis
• Facial canal between stapedius and chorda tympani
  • Facial paralysis (peripheral)
  • Loss of taste anterior 2/3 of tongue
  • No hyperacusis
• Distal facial canal lesions (stylomastoid foramen level):
  • Peripheral VII
  • No loss of taste
  • No hyperacusis
• Lesions distal to stylomastoid foramen:
  • Involvement of individual facial nerves:
    • Inflammation of retromandibular lymph nodes
    • Tumors (cylindroma, adenocarcinoma)
    • Obstetric forceps
    • Bell's palsy
    • Lyme's disease
    • Mycoplasma
    • Post infections (AIDP; CIDP)

Abnormalities of Eyelid Closure

• Decreased blinking:
  • Parkinson's disease (PD), basal ganglia disease, subcortical glial sclerosis (SCG), progressive supranuclear palsy, multiple symptoms atrophy (MSA), corticobasal ganglia degeneration (CBG), Balint's syndrome
• Increased blinking:
  • Any induced dyskinesia (dopamine agonists)
  • Schizophrenia
  • Gilles–de la Tourette's syndrome

Insufficiency of Eye Closure

• Supranuclear lesion
• Brainstem (nuclear lesion)
• Peripheral VII lesion
• Neuromuscular junction defects
• Precentral gyrus cortical or subcortical lesions: volitional eye closure paresis with normal mimetic eye closure
• Acquired inability to wink (Revilliod's sign); early sign of corticobulbar disease
• Compulsive eye opening (bilateral frontal or nondominant frontal lobe disease):
  • Reflex eye closure retained
  • Able to comprehend the task
  • Described with JCD (Jacob–Creutzfeldt)
• Apraxia of eyelid opening (prefrontal disease usually bilateral)
• Motor impersistence of eye closure:
  • Unable to complete the command to close the eyes
  • Eyes close; develop a fine tremor; then open
  • Seen with basal ganglia disease or bilateral hemispheric or non-dominant hemispheral disease

Excessive Eyelid Closure and Blepharospasm

• Contralateral frontal eye field seizure
• Blepharospasm:
  • Focal dystonia
  • Meige's syndrome (oromandibular dystonia)
  • May have concomitant spasmodic dysphonia or axial dystonia
  • Multiple sclerosis
  • Bilateral infarction of rostral brainstem; diencephalon and striatum
  • Irritable painful eye diseases
  • Tardive dyskinesia (drug induced)
  • Parkinson's disease
  • Wilson' disease
  • Hallervorden-Spatz disease
  • Familial apoceruloplasmin deficiency with retinal degeneration
  • Reflex blepharospasm after stroke of nondominant temporoparietal
  • Bilateral blepharospasm following bilateral parietal lobe degeneration

Abnormal Facial Movements

• Dyskinesia:
  • Spontaneous in the elderly
  • Side effect of neuroleptic drugs
  • Edentulous dyskinesia
  • Extrapyramidal disease
• Dystonia:
  • Extrapyramidal disease
  • Meige's syndrome (Brueghel's syndrome):
    • Sustained abnormal mouth movement
    • Platysma contraction
    • Sustained neck flexion
    • One or both arms and trunk may be involved
• Hemifacial spasm:
  • Intermittent spasm of the orbicularis oculi and orbicularis oris muscles; may spread to all facial muscles; stapedius involvement causes clicking
  • Often exacerbated by stress and fatigue
  • If bilateral spasms; they are syndromes and asymmetrical
  • Lesions of the CPA angle (most often aberrant artery of AICA):
    • Tumor
    • Vascular malformation
    • Dolichoectasia of VA
    • MS
    • Lacunar infarction
    • Brainstem displacement
    • Lesions of the root entry zone
    • Associated with multiple cranial neuropathy
    • Follows Bell's palsy
    • Trauma
• Postparalytic spasm and synkinetic movements:
  • Post paralytic hemifacial palsy (following Bell's palsy):
    • Crocodile tears (lacrimation with eating)
    • Jaw-winkling (opening mouth causes blinking; Marin–Amat phenomena)
• Facial myokymia:
  • Multiple sclerosis
  • Pontine glioma
  • GBS
  • Myokymia with spastic paretic facial contracture (dorsal pons lesion at the facial nucleus)
• Focal cortical seizures:
  • Lower precentral gyrus
  • Post ictal paralysis (spares the forehead)
• Tics and habit spasms:
  • Gilles de La Tourette syndrome
  • Psychogenic
• Myoclonus:
  • Associated with palatal myoclonus
  • Lesions of Mollaret's triangle (dentate, inferior olive and red nucleus or their connections)

Vascular Lesions Affecting VII

• MCA – central sulcal artery (pial branch of superior division)
• Internal capsule ischemia:
  • Anterior choroidal (artery) ("Top of the carotid")
  • Lenticulostriate (MCA)
  • Thalamoperforate (posterior cerebral)
  • Recurrent artery of Heubner (A1 of ACA)
• Lacunar infarction:
  • Corona radiata
  • Pons
  • Cerebral peduncle
  • Medulla
• AVM (pons or anywhere in the course of the nerve)
• Venous telangiectasia of pons (usually asymptomatic)
• Cavernous hemangioma (rebleed; pons > thalamus/IC > corona radiata)
• AICA infarction (infarcts peripheral branches of the nerve outside of the brainstem (internal auditory and subarcuate arteries)
• Basilar artery aneurysm (fusiform with blockage of perforators and short circumferential arteries)
• AICA aneurysm (spasm)
• Aberrant artery of AICA (nerve compression in CPA)
• Dolichoectasia of vertebral and basilar artery
• Millard–Gubler syndrome (short circumferential arteries)
• Foville syndrome (short circumferential arteries)

Collagen Vascular Disease/Arteritis

• SLE
• Periarteritis nodosa
• Sarcoid (vasculitic form)
• Giant cell arteritis
• Wegener's granulomatosis
• Mixed collagen vascular disease

Immune Mediated

• MS (direct involvement; myokymia)
• ADEM
• AIDP
• CIDP
• Post immunization
• Bell's palsy
• Necrotizing leukoencephalopathy (associated with increased serum IgM)
• PML (leukoencephalopathy – rare in pons)

Systemic Disease

• Diabetes
• Hypertension
• Amyloidosis
• Whipple's disease
• Sarcoid
• Heerfordt's syndrome (bilateral VII nerve and uveitis with sarcoid)
• Idiopathic hypertrophic pachymeningitis

Infections

• Herpes zoster (Ramsey-Hunt syndrome):
  • Acute facial paralysis; grouped vesicles in and behind the ear
  • Less than 1% of acute Bell's palsy
• Herpes simplex (HS)
• Few patients with new infection or reactivation of CMV, adenovirus, EBV; more common in association with HIV
• Otitis media:
  • 0.5 to 1% complicated by facial paralysis
• Leprosy
• Syphilis
• Osteomyelitis
• Bacterial meningitis
• Tuberculous meningitis
• Fungal meningitis
• Lyme disease (Bannwarth syndrome)
• Polio
• Trichinosis
• Cysticercosis
• Abscess of pons

Congenital Disease

• Trauma at time of birth 1/2000 deliveries
• Congenitally narrow facial canal
• Alexander's disease (AD/AR)
• Hemifacial spasm (narrow posterior fossa)
• New born neuropathic facial paralysis:
  • Intrapartum compression
  • Intrauterine posture
  • Forceps trauma
  • Nuclear aplasia
• Möbius syndrome (facial diplegia with VI nerve palsy):
  • Cardiofacial syndrome (lower lip weakness with cardiac anomalies)
  • Valetta–Van Lowe syndrome (associated)
  • Facial paralysis incomplete in 2/3 of patients; frontalis and orbicularis oculi > perioral muscles
  • Associated anomalies; ptosis; anterior lingual atrophy, pectoral muscle defects, clubfoot, mental retardation, arm malformations

Melkersson–Rosenthal Syndrome

• Recurrent facial palsy with facial edema
• Lingua plicata (scrotal tongue)
• Facial weakness begins prior to age 16
• Edema effects upper lip most frequently; persistence of swelling with time; permanent state of lip and facial enlargement
• Cheilitis granulomatosa (small granulomas found in diffusely edematous interstitial tissue)

Hereditary Facial Paralysis

• Some families have a juvenile onset
• Recurrent facial palsy
• May be in association with other cranial nerve palsies

Tumors Affecting the VII Nerve

• Pontine glioma
• Pilocystic astrocytoma
• Metastatic disease (solid tumors)
• Carcinomatosis of the meninges
• Intracranial metastases from pinealoma
• Melanoma metastasizes to the nerve
• Lymphoma
• Leukemia
• Parotid tumor (mixed parotid gland tumor)
• Adenocarcinoma of the salivary gland

Toxin/Physical Agents

• Ethylene glycol (in moon shine aka "smoke")
• X-RT; frequent myokymia; direct nerve damage

Traumatic Facial Paralysis

• Closed head injury:
  • Acute facial paralysis:
    • Longitudinal (parallel to the long axis of the petrous pyramid)
    • Transverse fracture of petrous pyramid
    • Temporal bone fracture demonstrated in almost all cases of traumatic fracture
  • Delayed onset facial paralysis:
    • Bleeding from the ear and evidence of temporal bone fracture prognostic for a delayed VII nerve paralysis
  • Surgical trauma (ear surgery primarily)
    • VII nerve paralysis may be immediate or delayed

Differential Diagnosis of Bilateral VII Nerve Palsy

• Syndromic:
  • Wernicke–Korsakoff (concomitant IIIrd and VIth)
  • Melkersson-Rosenthal (scrotal tongue)
  • Möbius (concomitant VIth nerve)
  • Steven–Johnson's syndrome (severe mucous membrane involvement)
  • Familial Finnish amyloidoses (abnormal sagging facies)
  • Kennedy's syndrome (with fasciculation)

Infections

• Lyme's
• HIV
• Ebstein–Barr
• Herpes Simplex
• Poliomyelitis
• HZ
• Mycoplasma pneumonia
• Leprosy
• Trichinosis
• Tuberculosis
• Cryptococcus
• Syphilis
• Rhombencephalitis (HS; rare other viruses)

Immune Mediated

• MS
• CIDP
• AIDP (classic)
• ADEM
• CM Fisher (variant)
• Bilateral Bell's palsy
• Graft versus host disease

Tumor

• Carcinomatosis of the meninges
• Leukemia (CLL)
• Nasopharyngeal cancer
• Pontine glioma
• Fibrillary astrocytoma
• Prepontine meningioma (meningioma en-plaque)

Systemic Disease

• Sarcoid (Heerfordt's syndrome)
• Diabetes (bilateral Bell's)
• Collagen vascular disease
• Pontine hemorrhage
• Head trauma