Facial paralysis

Background

Bilateral course of facial nerve. Note that the forehead muscles receive innervation from both hemispheres of the brain, which is why there is forehead sparing for stroke but not Bell's palsy (or other peripheral facial nerve injury).

• Facial paralysis (CN VII palsy) is a common ED presentation requiring distinction between central and peripheral causes
• Key distinction: central (upper motor neuron) vs. peripheral (lower motor neuron) — determines urgency of workup
• Central cause = forehead sparing (bilateral cortical input to forehead muscles) → evaluate for stroke
• Peripheral cause = forehead involvement (entire ipsilateral face) → Bell's palsy most common
• Bell's palsy is a diagnosis of exclusion — consider other peripheral causes before labeling as idiopathic

Causes

• Central (upper motor neuron)
  • Stroke/TIA — most critical to identify
  • Intracranial mass/tumor
• Peripheral (lower motor neuron)
  • Idiopathic (Bell's palsy) — accounts for ~60-75% of acute unilateral facial paralysis
  • Lyme disease — most common identifiable infectious cause in endemic areas; can be bilateral
  • Varicella-zoster (Ramsay Hunt syndrome) — vesicles in ear canal, severe pain
  • HSV reactivation
  • Otitis media (with or without cholesteatoma)
  • Facial trauma / temporal bone fracture
  • Parotid gland tumor
  • Guillain-Barré syndrome (can be bilateral)
  • Sarcoidosis (Heerfordt syndrome)

Clinical Features

A person attempting to show his teeth and raise his eyebrows with Bell's palsy on his right side; notice how the forehead is NOT spared.

Patient with stroke (forehead sparing).

Central Process (Forehead Sparing)

• Normal forehead muscle tone — patient can raise eyebrow and wrinkle forehead on affected side
• Weakness of lower face (nasolabial fold flattening, asymmetric smile)
• Often accompanied by other neurologic deficits (hemiparesis, speech changes, sensory loss)

Peripheral Process (Forehead Involved)

• Weakness of entire ipsilateral face including forehead
• Unable to close eye (risk of corneal exposure and injury)
• Loss of nasolabial fold
• Asymmetric smile
• May have associated symptoms depending on etiology:
  • Ear pain/vesicles (Ramsay Hunt syndrome)
  • Hyperacusis (stapedius muscle involvement)
  • Decreased taste (chorda tympani involvement)
  • Dry eye (greater petrosal nerve involvement)

Red Flags

• Forehead sparing → consider stroke (activate stroke protocol)
• Bilateral facial weakness → consider Lyme disease, Guillain-Barré syndrome, sarcoidosis
• Slowly progressive (>3 weeks) → consider tumor
• Vesicles in ear canal → Ramsay Hunt syndrome (requires antivirals)
• Recent tick exposure or erythema migrans → Lyme disease
• Recurrent episodes → consider tumor, sarcoidosis, or Melkersson-Rosenthal syndrome

Differential Diagnosis

Facial paralysis

• Bell's palsy
• CVA
• Trigeminal neuralgia
• Tick paralysis
  • Lyme disease
• Herpes zoster oticus (Ramsay Hunt syndrome)
• CNS tumor
  • Acoustic neuroma or other cerebellopontine angle lesions
  • Meningioma
  • Cerebellar pontine angle
  • Facial nerve schwannoma
  • Parotid
  • Sarcoma
• Anesthesia nerve blocks
• Cerebral Aneurysms (vertebral, basilar, or carotid)

Evaluation

Central Process

• Activate stroke protocol if acute onset with forehead sparing
• CT head emergently; CT angiography
• Consider MRI brain
• Standard stroke workup

Peripheral Process

• No labs or imaging routinely necessary for classic Bell's palsy presentation
• Examine ear canal for vesicles (Ramsay Hunt syndrome)
• Consider Lyme serologies if endemic area, bilateral involvement, recent tick exposure, or erythema migrans
• Consider CBC, ESR, CRP, BMP if atypical features
• Consider MRI with gadolinium if: atypical course, slowly progressive, no improvement at 3 weeks, recurrent episodes
• CT temporal bone if history of trauma

Eye Examination

• Assess corneal closure — inability to fully close eye requires eye protection measures
• Fluorescein stain to evaluate for corneal abrasion/exposure keratopathy

Management

Central Process

• Treat underlying pathology (stroke protocol, neurosurgical consultation for mass)

Peripheral Process (Bell's Palsy)

• Prednisone 60-80mg daily x 7 days (started within 72 hours of onset) — strongest evidence for improved recovery
• Eye care: artificial tears during day, lubricating ointment at night, tape or patch eyelid closed during sleep
• Consider valacyclovir 1g TID x 7 days for severe facial paralysis (House-Brackmann grade IV-VI) — evidence is mixed but may provide modest benefit when combined with steroids
• Empiric doxycycline if high suspicion for Lyme disease (do NOT give steroids alone if Lyme suspected)

Ramsay Hunt Syndrome

• Valacyclovir or acyclovir + prednisone
• Has worse prognosis than Bell's palsy — ENT/neurology follow-up

Disposition

Discharge (Most Patients)

• Most patients with peripheral facial paralysis can be discharged
• Ensure adequate eye protection education (corneal desiccation is the main complication)
• Follow-up with primary care in 1-2 weeks; neurology or ENT if no improvement in 3-4 weeks
• Return precautions: worsening symptoms, new neurologic deficits, vision changes

Admit

• Central process (stroke protocol)
• Bilateral facial paralysis (evaluate for Guillain-Barré, Lyme, sarcoidosis)
• Ramsay Hunt syndrome with severe involvement (consider IV antivirals)

See Also

• Bell's palsy
• Stroke
• Ramsay Hunt syndrome
• Lyme disease
• Facial swelling