Facial Nerve Palsy

Physical Examination

• Unilateral facial weakness or asymmetry

• Inability to raise eyebrows

• Inability to close eyes completely

• Loss of nasolabial fold

• Drooping of the mouth corner

• Difficulty with whistling or blowing

• Tearing or drooling

• Hyperacusis (increased sensitivity to sound) on the affected side

• Altered taste sensation on the anterior two-thirds of the tongue

Lesion level

• Pons: linked to cranial nerve VI impairment, long tract indicators, and contralateral motor/sensory deficits

  • Possible reasons: multiple sclerosis, cerebrovascular accidents, brainstem tumours

• Cerebellopontine angle: connected to cranial nerves V, VI, VIII, cerebellar manifestations, and trigeminal nerve dysfunction

  • Possible reasons: neoplasms (vestibular schwannoma, meningioma)

• Auditory/facial canal: related to cranial nerve VIII issues and potential facial nerve compression

  • Possible reasons: cholesteatoma, abscess formation

• Neck and face: connected to scars, parotid gland mass, and possibly cervical lymphadenopathy

  • Possible reasons: neoplastic growth (parotid gland tumours, metastatic disease), physical injury, inflammatory conditions (sarcoidosis, granulomatosis with polyangiitis)

Causes of lower motor neuron lesions of facial nerve palsy

• Bell's palsy: idiopathic facial nerve palsy, most common cause

• Infections:

  • Ramsay Hunt syndrome: herpes zoster oticus, affecting the facial nerve and ear

  • Lyme disease: caused by Borrelia burgdorferi, transmitted by ticks

  • Otitis media: middle ear infection may cause facial nerve involvement

• Trauma:

  • Temporal bone fractures: may damage the facial nerve

  • Iatrogenic injury: facial nerve damage during ear or parotid gland surgery

• Neoplastic growth:

  • Parotid gland tumours: benign or malignant, compressing the facial nerve

  • Facial nerve schwannoma: benign tumour arising from Schwann cells

  • Metastatic disease: involvement of facial nerve by metastatic cancer

• Inflammatory conditions:

  • Sarcoidosis: granulomatous inflammation may affect the facial nerve

  • Granulomatosis with polyangiitis: systemic vasculitis, may involve facial nerve

• Vascular causes:

  • Diabetes mellitus: microvascular damage leading to facial nerve ischemia

  • Hypertension: contributing to microvascular changes and nerve ischemia

• Congenital:

  • Moebius syndrome: congenital facial and abducens nerve palsy

Causes of bilateral lower motor neuron (LMN) facial nerve palsy

• Bilateral Bell’s palsy

• Guillain-Barré syndrome

• Sarcoidosis

• Lyme disease

• Infectious mononucleosis (Epstein-Barr virus infection)

• Neurofibromatosis type 2

• Bilateral parotid gland tumours

Investigations

• Complete blood count: assess for signs of infection, anaemia, or other haematological abnormalities

• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP): evaluate for inflammation or autoimmune conditions

• Blood glucose and HbA1c: screen for diabetes mellitus

• Serology:

  • Lyme disease: Borrelia burgdorferi IgM and IgG antibodies

  • Varicella-zoster virus (VZV): VZV-specific IgM and IgG antibodies for Ramsay Hunt syndrome

  • Epstein-Barr virus: serological tests for infectious mononucleosis

• Autoantibodies:

  • Antinuclear antibody (ANA), anti-neutrophil cytoplasmic antibodies (ANCA), and rheumatoid factor (RF): screen for autoimmune or vasculitic conditions

• Lumbar puncture: cerebrospinal fluid (CSF) analysis for infection, inflammation, or malignancy

  • Cell count, glucose, protein, Gram stain, culture, and sensitivity

  • VZV PCR for Ramsay Hunt syndrome

  • Lyme disease PCR or antibody index

  • Malignancy: cytology and flow cytometry

• Imaging:

  • MRI of the brain and internal auditory canal: assess for cerebellopontine angle lesions, brainstem pathology, or neoplasms

  • CT of the temporal bone: evaluate for fractures, cholesteatoma, or neoplastic involvement

  • Ultrasound or CT of the parotid glands: investigate for parotid gland masses or inflammation

• Electromyography (EMG) and nerve conduction studies: assess facial nerve function and distinguish from other neuropathies

• Audiometry: evaluate hearing function, particularly in cases with suspected vestibulocochlear nerve involvement

• Biopsy:

  • Parotid gland or lymph node biopsy: investigate suspected neoplastic or granulomatous processes

  • Skin or muscle biopsy: if considering sarcoidosis or vasculitis

• Additional specialised tests:

  • Schirmer's test: assess for dry eye due to impaired lacrimal gland function

    • The test is performed by placing filter paper inside the lower eyelid. After 5 minutes, the paper is removed and tested for its moisture content. A score of greater than 10 mm in 5 minutes is accepted as normal. A score of less than 5 mm in 5 minutes indicates a tear deficiency.

  • Ophthalmological evaluation: detect corneal exposure complications

Management

General management:

• Eye care: protect the affected eye from drying and exposure

  • Lubricating eye drops or ointment

  • Eye patch or taping the eyelids shut during sleep

  • Regular follow-up with an ophthalmologist

Medical management:

• Corticosteroids: reduce inflammation and nerve swelling, e.g., prednisolone

• Antiviral therapy: for Ramsay Hunt syndrome or herpes zoster, e.g., acyclovir or valacyclovir

• Antibiotics: for bacterial infections such as Lyme disease or otitis media

• Analgesics: manage pain associated with facial nerve palsy

• Physical therapy: facial exercises and massage to maintain muscle tone and prevent contractures

Surgical management:

• Decompression surgery: in select cases of severe facial nerve compression or persistent paralysis

• Tympanomastoid surgery: for cholesteatoma or chronic otitis media

• Parotid gland surgery: for benign or malignant parotid gland tumors

• Nerve grafting or transfer: in cases of irreversible facial nerve damage

Other management:

• Psychological support: counselling or therapy to cope with the emotional impact of facial nerve palsy

• Speech therapy: improve facial muscle coordination and speech if necessary

• Alternative therapies: acupuncture or biofeedback may provide relief in some cases

• Monitoring and follow-up: regular assessment of facial function and ongoing management of the underlying cause