Facial weakness and asymmetry

Facial weakness is reduced movement of the muscles of facial expression, producing drooping, loss of expression, or asymmetry at rest or on movement. The first step is to separate an upper motor neuron pattern, which may be a stroke needing immediate treatment, from a lower motor neuron pattern, most often Bell palsy. The minority of lower motor neuron palsies with a specific cause must also be identified.

Clinical relevance. Missed stroke is the main danger. In lower motor neuron palsy the main risks are corneal injury from poor eye closure, missed Ramsay Hunt syndrome, otogenic complications, tumour, and persistent weakness with synkinesis.

Anatomy.

• The facial motor nucleus lies in the lower pons.
• The nerve exits at the pontomedullary junction, crosses the cerebellopontine angle with the vestibulocochlear nerve, and enters the internal acoustic meatus and the facial canal.
• It gives off the greater petrosal nerve (lacrimation) at the geniculate ganglion, the nerve to stapedius (hyperacusis) and the chorda tympani (taste to the anterior two thirds of the tongue).
• It leaves at the stylomastoid foramen and divides in the parotid gland.

Upper versus lower motor neuron. The upper face (frontalis and orbicularis oculi) receives bilateral cortical input, so a cortical or subcortical lesion causes lower face weakness with forehead sparing, and emotional movement may be preserved. A lesion of the nucleus or nerve causes weakness of the whole ipsilateral face including the forehead.

Grading. House Brackmann grades I (normal) to VI (no movement). Grade III is moderate with obvious but not disfiguring weakness and complete eye closure with effort. Grade IV and over indicates incomplete eye closure.

Bell palsy. An acute, idiopathic, unilateral lower motor neuron palsy that reaches maximum severity within 72 hours and is a diagnosis of exclusion. It is often associated with reactivation of herpes simplex virus. About 70 percent recover completely without treatment, and corticosteroids improve this further. Recovery begins within 3 weeks in most.

Temporal patterns. Sudden (stroke, haemorrhage, trauma), evolving over hours to 3 days (Bell palsy, Ramsay Hunt syndrome), progressive over more than 3 weeks (tumour), recurrent, or present from birth.

History.

• Onset and speed (abrupt in seconds to minutes suggests vascular)
• course
• pain behind the ear
• hyperacusis
• altered taste
• reduced tear or excess tears
• dry or watering eye
• drooling
• speech and drinking difficulty
• headache
• ear discharge or earache
• vesicles in the ear or mouth
• hearing loss
• tinnitus
• vertigo
• recent upper respiratory infection
• tick bite or erythema migrans
• travel
• HIV risk
• diabetes
• pregnancy
• recent dental or ear surgery or trauma
• previous episodes
• facial swelling or mass
• skin cancer
• limb weakness
• other cranial nerve symptoms

Examination

• Observe the face at rest and in conversation. Test forehead wrinkling, eyebrow raise, eye closure (note Bell phenomenon, upward eye rolling), blink, nasolabial fold, smile, tooth showing, cheek puffing and platysma; grade with House Brackmann.
• Ears: vesicles on the pinna, meatus or palate, otoscopy for otitis media, cholesteatoma, perforation and discharge, mastoid tenderness; Weber and Rinne tests, audiometry.
• Parotid gland palpation, neck nodes, skin of the face, and scalp.
• Other cranial nerves: corneal reflex (V), eye movements (III, IV, VI), hearing (VIII), palate and tongue (IX to XII).
• Limb power, speech, visual fields, gait and blood pressure.
• Eye: lagophthalmos, corneal staining with fluorescein, red eye and visual acuity.

Red flags

• Forehead sparing, or limb weakness, speech or visual disturbance (stroke)
• Sudden onset in seconds to minutes, or with severe headache, vomiting or reduced consciousness
• Vesicles in the ear, mouth or face (Ramsay Hunt syndrome)
• Ear discharge, mastoid tenderness, fever, or diabetes with severe ear pain (malignant otitis externa)
• Hearing loss, vertigo or other cranial nerve palsies (cerebellopontine angle or skull base lesion)
• Parotid mass, skin cancer, or neck mass
• Progressive weakness beyond 3 weeks, no improvement at 3 to 4 months, or recurrent ipsilateral palsy
• Bilateral facial weakness (Guillain Barré syndrome, Lyme disease, sarcoidosis, HIV, myasthenia)
• Head injury or temporal bone fracture
• Eye pain, redness, photophobia or reduced vision
• Pregnancy with hypertension and proteinuria
• Immunosuppression or HIV

Special groups. Pregnancy: Bell palsy is more frequent in the third trimester and early postpartum, so check blood pressure and urine protein for pre-eclampsia. Children: Lyme disease, acute otitis media, trauma and congenital causes; neonates with birth injury (forceps) usually recover. Older adults: stroke and herpes zoster oticus. Region specific: leprosy, HIV, tuberculous otitis media and sarcoidosis.

Upper motor neuron (central) pattern

• Ischaemic stroke (middle cerebral artery, lacunar, brainstem), transient ischaemic attack
• Intracerebral haemorrhage, subarachnoid haemorrhage
• Brain tumour, abscess, subdural haematoma
• Multiple sclerosis, post-ictal Todd paresis, hemiplegic migraine, cerebral venous thrombosis

Lower motor neuron, unilateral

• Bell palsy (idiopathic)
• Ramsay Hunt syndrome (varicella zoster)
• Lyme disease, HIV (seroconversion and advanced disease), cytomegalovirus, Epstein Barr virus, syphilis, tuberculosis, mumps
• Otitis media (acute and chronic suppurative), cholesteatoma, mastoiditis, malignant otitis externa
• Temporal bone fracture, facial nerve injury (parotid, ear and skull base surgery, dental block, birth trauma)
• Tumours: parotid, cerebellopontine angle (vestibular schwannoma, meningioma), facial nerve schwannoma, glomus tumour, cholesteatoma, skull base metastasis, nasopharyngeal carcinoma, perineural spread of skin cancer, leukaemic and lymphomatous infiltration
• Brainstem lesions: pontine infarct, glioma, multiple sclerosis (with sixth nerve palsy or long tract signs)
• Sarcoidosis (Heerfordt syndrome), Melkersson Rosenthal syndrome, diabetic mononeuropathy, vasculitis (granulomatosis with polyangiitis), Sjogren syndrome
• Leprosy

Bilateral

• Guillain Barré syndrome and Miller Fisher syndrome
• Lyme disease, sarcoidosis, HIV, Epstein Barr virus, syphilis
• Bilateral Bell palsy (sequential), carcinomatous or lymphomatous meningitis
• Myasthenia gravis, myotonic dystrophy, facioscapulohumeral muscular dystrophy, Moebius syndrome
• Basal skull fracture, brainstem lesion

Mimics

• Long standing facial asymmetry (examine old photographs), hemifacial spasm with contralateral appearance of weakness
• Ptosis (myasthenia gravis, Horner syndrome, oculomotor palsy), facial swelling, post-dental swelling
• Parkinson disease (hypomimia), botulinum toxin effect, temporomandibular joint disorder
• Functional facial weakness, congenital unilateral lower lip palsy (asymmetric crying facies)

Reasoning. Look at the forehead first. A pattern that spares the forehead, or any limb or speech sign, is a stroke until imaging says otherwise. A lower motor neuron palsy developing over up to 72 hours with no other signs and a normal ear and parotid examination is Bell palsy. Everything else needs a cause sought.

Bedside tests for all. Blood pressure, glucose, temperature, ear and oropharyngeal examination for vesicles, otoscopy, corneal examination with fluorescein, and a full cranial nerve and limb examination. Pregnancy test and urine protein in women of reproductive age with new weakness.

Upper motor neuron pattern. Emergency CT head, with CT angiography and perfusion or MRI with diffusion weighted imaging.

Typical Bell palsy. Imaging and nerve conduction are not needed. Check HbA1c if diabetes risk, and HIV and Lyme serology when risk factors, bilateral weakness or tick exposure are present.

Atypical features. MRI brain with contrast and thin slices through the internal acoustic meatus and facial canal for:

• progression beyond 3 weeks
• no improvement at 3 to 4 months
• recurrent ipsilateral palsy
• other cranial nerve involvement
• hearing loss or vertigo
• pain out of proportion
• a parotid or neck mass

CT temporal bone for trauma, suspected cholesteatoma, mastoiditis or malignant otitis externa.

Other tests

• Varicella zoster PCR from vesicle fluid; audiometry for hearing loss in Ramsay Hunt syndrome.
• Nerve conduction studies and electromyography for severe palsy (grade V to VI) from day 3 to 14: reduction of the compound muscle action potential to under 10 percent of the normal side (over 90 percent degeneration) predicts poor recovery.
• Blink reflex and needle examination show denervation and reinnervation.
• Lyme serology by a two tier method (screening immunoassay followed by confirmation), and lumbar puncture for suspected meningitis, Lyme neuroborreliosis or Guillain Barré syndrome (after imaging when indicated).
• Full blood count, ESR, C reactive protein, glucose and HbA1c, HIV and syphilis serology, angiotensin converting enzyme, ANCA, antinuclear antibody, chest X-ray or CT for sarcoidosis, acetylcholine receptor antibodies for suspected myasthenia gravis.
• Biopsy for suspected parotid or skin malignancy.

Limitations. Imaging in the first hours can miss small brainstem infarcts. Facial nerve enhancement on MRI is common in Bell palsy and does not suggest tumour. Early electrodiagnostic tests can be normal in the first 3 days because Wallerian degeneration is not yet complete.

Protect the eye (all patients with incomplete eye closure).

• Lubricating drops (hypromellose 0.3 percent or carbomer gel) every 1 to 2 hours while awake, and eye ointment (liquid paraffin or white soft paraffin) at bedtime.
• Tape the eyelid closed at night (soft hypoallergenic tape, not over the lashes), use wrap around glasses or a moisture chamber outdoors.
• Same day ophthalmology for eye pain, redness, photophobia, reduced vision or corneal staining.
• Persistent lagophthalmos: specialist referral for tarsorrhaphy or upper eyelid weight.

Bell palsy

• Prednisolone 50 mg orally once daily for 10 days (or 60 mg daily for 5 days, then reduced by 10 mg each day for 5 days), started within 72 hours of onset. Benefit is greatest when started early; evidence for later starts is weaker.
• Check glucose in diabetes, add gastric protection in peptic ulcer disease, caution in hypertension, psychiatric illness and immunosuppression.
• Children: prednisolone 1 mg/kg daily (maximum 50 mg) for 7 to 10 days (evidence is limited). In pregnancy, prednisolone is acceptable after the first trimester when the benefit justifies it.
• Antiviral drugs alone do not help. For severe palsy (House Brackmann V to VI) valaciclovir 1 g orally three times daily for 7 days may be added to prednisolone, although added benefit is small and uncertain.
• Adjust valaciclovir: creatinine clearance 30 to 49 mL/min, 1 g every 12 hours; 15 to 29 mL/min, 1 g daily; under 15 mL/min, 500 mg daily.
• Facial exercises and physiotherapy; avoid electrical stimulation. Botulinum toxin and specialist therapy for synkinesis and hemifacial contracture later.

Ramsay Hunt syndrome

• Prednisolone 1 mg/kg orally daily (maximum 60 mg) for 7 days, then reduced over 7 days, with valaciclovir 1 g orally three times daily for 7 days, started within 72 hours of onset where possible.
• Aciclovir 800 mg orally five times daily for 7 days is an alternative to valaciclovir (adjusted: creatinine clearance 10 to 25 mL/min, 800 mg every 8 hours; under 10 mL/min, 800 mg every 12 hours).
• Immunocompromised, severe or disseminated disease: aciclovir 10 mg/kg IV every 8 hours for 7 to 10 days, adjusted for kidney function with hydration.
• Analgesia, eye care, audiology and ENT review. Warn of post-herpetic neuralgia, treated with amitriptyline 10 mg at night increased by 10 mg weekly to 25 to 75 mg, gabapentin 300 mg at night increased every 3 to 7 days, or pregabalin 75 mg twice daily increased as tolerated.

Lyme disease. Doxycycline 100 mg orally twice daily for 14 to 21 days in adults (amoxicillin 500 mg orally three times daily for 14 to 21 days in pregnancy, breastfeeding and children under 8 years). Meningitis or central involvement: ceftriaxone 2 g IV daily for 14 to 21 days. Corticosteroids are not routinely added.

Otogenic causes.

• Acute otitis media with facial palsy: ceftriaxone 2 g IV daily, or amoxicillin clavulanate, with urgent ENT review for myringotomy.
• Mastoiditis or cholesteatoma: ENT surgery.
• Malignant otitis externa (diabetes, immunosuppression, severe ear pain): admit, ceftazidime 2 g IV every 8 hours or ciprofloxacin 400 mg IV every 8 to 12 hours initially.
• Then oral ciprofloxacin 750 mg twice daily (adjust for creatinine clearance; QT and tendon warnings), for a minimum of 6 weeks, with glycaemic control and ENT surgical review.

Acute ischaemic stroke. Immediate stroke team.

• Alteplase 0.9 mg/kg IV (maximum 90 mg), 10 percent as a bolus over 1 minute and the remainder over 60 minutes, within 4.5 hours of onset when haemorrhage is excluded.
• Or tenecteplase 0.25 mg/kg IV as a single bolus (maximum 25 mg).
• Blood pressure under 185/110 mmHg before thrombolysis and under 180/105 mmHg for 24 hours after.
• Aspirin 300 mg orally daily for 14 days when thrombolysis is not given, then long term single antiplatelet therapy.
• Thrombectomy referral for large vessel occlusion.

Other causes

• Guillain Barré syndrome: intravenous immunoglobulin 0.4 g/kg daily for 5 days, with forced vital capacity monitoring twice daily.
• Sarcoidosis: prednisolone 40 mg orally daily with specialist review.
• Tumour, parotid mass, cerebellopontine angle lesion: ENT, neurosurgery and oncology referral.
• Trauma and nerve transection: surgical exploration by a facial nerve surgeon; immediate complete palsy after temporal bone fracture needs specialist assessment.
• Myasthenia gravis: neurology referral, with pyridostigmine started by specialists and avoidance of aggravating drugs (fluoroquinolones, aminoglycosides, macrolides, magnesium, beta blockers).
• Melkersson Rosenthal syndrome and recurrent palsy: specialist review.
• Leprosy:
  • rifampicin 600 mg once monthly (supervised)
  • clofazimine 300 mg once monthly (supervised) and 50 mg daily
  • dapsone 100 mg daily for 12 months in multibacillary disease or 6 months in paucibacillary disease
  • prednisolone 40 mg orally daily reduced gradually over several months for nerve function impairment
  • specialist care

Prognosis and persistent palsy. Most Bell palsy recovers within 3 weeks to 3 months. A minority have residual weakness, contracture or synkinesis. Persistent palsy after 6 to 12 months: facial reanimation (static slings, nerve cross over, free muscle transfer) through a facial plastic surgical service.

Monitoring. House Brackmann grade at 1 week, 3 weeks and 3 months. Eye symptoms and corneal staining at each review. Glucose and blood pressure on prednisolone. Hearing and vertigo in Ramsay Hunt syndrome.

Referral and escalation. Immediate: stroke pattern, suspected intracranial lesion, head or temporal bone trauma, malignant otitis externa with systemic features, corneal injury. Urgent ENT or neurology review if no improvement by 3 weeks, any progression beyond 3 weeks, or atypical features. Ophthalmology for persistent lagophthalmos. Facial plastic or reconstructive surgery for persistent palsy.

Admission criteria. Suspected stroke, intracranial or skull base lesion, serious ear infection with complications, immunocompromised Ramsay Hunt syndrome, Guillain Barré syndrome, or inability to protect the eye.

Discharge and safety netting. Review at 1 week and 3 weeks. Return urgently for eye pain, redness or visual change, new limb weakness, speech disturbance, severe headache, drowsiness, new ear discharge, hearing loss, vertigo, spreading rash, or worsening weakness after 3 days.