Cranial Nerve Palsy

BASICS


DESCRIPTION


• The facial nerve is the VII cranial nerve.


– Innervation:


– Muscles of facial expression


– Sympathetic efferents to lacrimal and salivary glands


– Sensory afferents from tongue, external ear, and palate


– Taste afferents from anterior two-thirds of tongue


– Motor dysfunction causes ipsilateral facial paralysis


• Bell’s Palsy (Idiopathic): Most common cause of unilateral facial paralysis


– Acute to subacute (hours to days) onset of unilateral upper and lower facial weakness with variable symptoms of hyperacusis, dysgeusia, and dysfunctional lacrimation and salivation.


• Initial determinations:


– Peripheral versus central


– Accompanying clinical signs and symptoms indicating a non-idiopathic etiology


Non-isolated & central VII nerve palsy requires work-up



ALERT


Bilateral facial nerve palsy and concomitant additional cranial neuropathies require special attention.


EPIDEMIOLOGY


Incidence


11–40/100,000 per year (1)[A]; more common ages 15–45 years


Prevalence


None recently reported


RISK FACTORS


Bell’s Palsy: Pregnancy, diabetes, influenza, upper respiratory infection


Genetics


• Bell’s Palsy: Sparse reports of familial cases


• Mobius syndrome: Congenital facial diplegia + variable abducens nerve palsy; sporadic


• Myotonic dystrophy: Autosomal dominant trinucleotide (CTG) repeat expansion on 19q13.3


PATHOPHYSIOLOGY


Supranuclear, nuclear, infranuclear/peripheral dysfunction of the facial nerve


ETIOLOGY


Bell’s Palsy: Idiopathic, possible viral-associated inflammation and/or demyelination


COMMONLY ASSOCIATED CONDITIONS


None known; see risk factors.


DIAGNOSIS


HISTORY


• Bell’s Palsy: Isolated, acute to subacute onset of unilateral upper and lower facial weakness with variably manifested hyperacusis, dysgeusia, and dysfunctional lacrimation and salivation


– Assess: Dysarthria, dysphagia, change of hearing and taste, ear and eye pain, diplopia, vertigo, ataxia, gait dysfunction, limb weakness, rashes, facial numbness, and pain


– Myasthenia Gravis (MG): Variable ptosis and diplopia, fatigable extremity weakness


– Demyelination/multiple sclerosis (MS): History of prior focal neurological deficits


– Guillain-Barré Syndrome (GBS): Preceding GI or upper respiratory infection


– Additional history: Trauma, neoplasia, ischemia, demyelinating disease


– Guides appropriate work-up for secondary causes


– Pain is atypical for Bell’s Palsy


– Consider Ramsay-Hunt Syndrome: HZV with vesicular eruption


– Systemic symptoms


PHYSICAL EXAM


• Determine if palsy is central or peripheral and if palsy exists in isolation


– At rest: Note asymmetry of muscle tone, blink pattern, widened palpebral fissure, flattened nasolabial fold, and lagophthalmus


• Motor activity: Smile and forced eyelid closure


– Note decreased function on affected side; Bell’s phenomenon


– Asses forehead/frontalis function


Ask patient to raise/furrow eyebrows and brow


Central palsies do not affect function of forehead/frontalis; peripheral palsies do


• Examine corneal sensation and reflex


• Examine other cranial nerves: V, VI, and VIII are of particular importance for anatomic localization.


• Examine for long tract signs, for example, extremity weakness.


DIAGNOSTIC TESTS & INTERPRETATION


Lab


Initial lab tests

Serum glucose, syphilis serology, CBC, Lyme titer, ACE, HgbA1c


Follow-up & special considerations

Consider: ESR, CRP, ANA, anti-acetylcholine receptor Abs, mono spot test, ANCA, HIV, CSF analysis, serology/stool culture for C. jejuni


Imaging


Initial approach

• MRI is modality of choice to rule out secondary causes except in trauma cases (CT)


• Presentations requiring imaging


– Slow or insidious onset of palsy


– Central and bilateral nerve palsies


– Multiple cranial neuropathies


– Associated hearing loss and vertigo


– Attention: Ischemia (diffusion weighted images), masses, CP angle, pachymeningeal enhancement (sarcoid), meningoencephalitis (Lyme), skull base, and brainstem


Follow-up & special considerations

Disease specific for secondary causes


Diagnostic Procedures/Other


• EMG: GBS & MG; include repetitive stimulation, consider single fiber EMG


• CSF: Pleocytosis (infectious/inflammatory), albuminocytologic dissociation (GBS), Lyme, Ig index and oligoclonal bands (MS), ACE (sarcoid) and infectious work-up as appropriate


• Edrophonium test and Ice test (MG)


• Chest x-ray (sarcoid related adenopathy)


Pathological Findings


Mobius syndrome: Aplasia/hypoplasia of cranial nerve nuclei


DIFFERENTIAL DIAGNOSIS


• Infectious, inflammatory/demyelinating, infiltrative, neoplastic/metastatic, compressive, traumatic, and idiopathic


– Supranuclear: Ischemia, mass lesion


– Nuclear: Pontine glioma, ischemia, hemorrhage, demyelination, vascular lesions


– Infranuclear


– Cerebellopontine (CP) angle: Acoustic schwannoma, meningioma, choleastoma, glomus jugulare tumor (can involve cranial nerves VII – XII)


– Temporal bone/Skull base: Osteopetrosis, trauma, masses, Ramsay-Hunt syndrome, hemangioma, naso-pharyngeal carcinoma


– Subarachnoid space: Carcinomatous meningitis, GBS, TB, sarcoid, Lyme


– Other: MG, syphilis, parotid tumors, amyloid, sarcoma, diabetic mononeuropathy, HIV, lymphoma/leukemia, demyelination/MS, Paget’s disease, arteriovenous malformation


• Bilateral VII Nerve palsy: Lyme disease, sarcoidosis, carcinomatous or infectious meningitis, GBS/Miller Fisher Syndrome, myasthenia gravis, leprosy, leukemia/lymphoma


Pediatric Considerations


• Acute otitis media


TREATMENT


MEDICATION


• Bell’s Palsy: Antiviral agents (most commonly acyclovir or valacyclovir)


– Incomplete facial motor function recovery at 1 year:


Antivirals versus (vs.) placebo: No significant difference: Relative Rate (RR): 0.88 (1)[A]


Antivirals and corticosteroids versus placebo: Significantly better outcomes: RR: 0.56 (1)[A]


Adverse events (antivirals vs placebo): No significant differences: RR: 1.06


Conclusions: Antivirals versus placebo: Do not enhance complete functional recovery (high quality); antivirals versus corticosteroids: Significantly less likely to produce complete recovery (moderate quality) (1)[A]


• Bell’s Palsy: Corticosteroids


– Incomplete facial motor function recovery ≥6 months:


Corticosteroids 23%, Placebo 33%; RR 0.71 (2)[A]


Motor synkinesis was significantly reduced with corticosteroids versus placebo: RR 0.6 (2)[A]


Conclusion: Evidence reveals significant benefit from corticosteroids (2)[A]


• Recommendations


– Early initiation of corticosteroids is of benefit:


Sullivan et al. (3)[A]: Prednisolone 25 mg b.i.d for 10 days


Engstrom et al. (4)[A]: Prednisolone 60 mg daily × 5 days followed by 10 mg/day taper over 5 days


Antiviral therapy has no proven benefit; some practitioners recommend use in severe or complete palsies.


ADDITIONAL TREATMENT


General Measures


• Ophthalmic concerns: Prevention of exposure keratitis and corneal injury


– Lubrication: Artificial tears, methylcellulose-based ointment, eye patching, and/or moisture chamber qhs.


– Surgical management required with potential or ongoing corneal injury.


Issues for Referral


• Corneal exposure


• Acute nerve trauma or transection: Consider primary neurorrhaphy


COMPLEMENTARY & ALTERNATIVE THERAPIES


Acupuncture and physical therapy lack adequate evidence.


SURGERY/OTHER PROCEDURES


• Facial nerve decompression lacks sufficient evidence (5)


• Surgical management: Corneal sequela


– Gold weight implant (upper lid) or tarsorrhaphy


For incomplete eyelid closure


Prevents and treats corneal injury


ONGOING CARE


FOLLOW-UP RECOMMENDATIONS


• Idiopathic/uncomplicated cases: 1–2 weeks, thereafter as appropriate.


• Corneal exposure requires ophthalmic monitoring.


Corneal status dictates frequency: Initial daily follow-up required for corneal breakdown or ulceration.


Patient Monitoring


Diabetics: Serum glucose monitoring during steroid therapy.


PATIENT EDUCATION


Prevention and symptoms of corneal injury


PROGNOSIS


• Bell’s Palsy: Functional recovery excellent in >80%


– Improved functional outcomes with incomplete palsies and early onset recovery (<3 weeks)


– More complete palsies: Higher likelihood of incomplete recovery and aberrant regeneration


– Poorer prognosis: Hyperacusis, decreased tearing, hypertension, age >60 years, diabetes, psychiatric disease, pregnancy


• Recovery dependent on site and extent of nerve injury


• EMG and nerve conduction studies: Preservation of motor amplitudes indicates axonal continuity and suggests good prognosis for recovery.


Pediatric Considerations


• Neoplastic and congenital etiologies associated with incomplete recovery


COMPLICATIONS


• Aberrant regeneration resulting in: Motor Synkinesis or Crocodile Tears


• Hemifacial Spasm


• Treatment: Chemodenervation with botulinum toxin



REFERENCES


1. Lockhart P, Daly F, Pitkethly M, et al. Antiviral treatment for Bell’s palsy (idiopathic facial paralysis). Cochrane Database Syst Rev 2009; (4): CD001869. [A]


2. Salinas RA, Alvarez G, Daly F, et al. Corticosteroids for Bell’s palsy (idiopathic facial paralysis). Cochrane Database Syst Rev 2010;(3):CD001942. [A]


3. Sullivan FM, Swan IRC, Donnan PT, et al. Early treatment with prednisolone or acyclovir in Bell’s Palsy. N Engl J Med 2007;357:1598–1607. [A]


4. Engstrom M, Berg T, Stjernquist-Desatnik A, et al. Prednisolone and valaciclovir in Bell’s palsy: A randomised, double-blind, placebo-controlled, multicentre trial. Lancet Neurol 2008;7:993–1000. [A]


5. Grogan P, Gronseth GS. Practice parameter: Steroids, acyclovir, and surgery for Bell’s Palsy (an evidence-based review): Report of the Quality Standards Subcommittee of the AAN. Neurology 2001;56: 830–836.

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Nov 9, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on Cranial Nerve Palsy

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