Facial palsy

Facial palsy refers to the neurological syndrome of facial paralysis. It can result from a broad range of physiological insults to the facial nerve or its central nervous system origins. The most common causes of this is Bell palsy.

Terminology

While facial palsy refers to the clinical presentation of facial paralysis and associated symptoms of facial nerve compromise it can sometimes be used interchangeably with facial nerve palsy which refers specifically to paralysis caused by a lesion in the facial nerve.

The distinction is important as facial nerve palsy implies almost an exclusively lower motor neurone cause of facial paralysis while the term facial palsy can include upper motor neurone lesions as well.

Clinical presentation

The facial nerve provides innervation to the facial muscles, middle ear, tongue, salivary and lacrimal glands. Accordingly signs and symptoms of facial nerve palsy include:

• dropping mouth

• loss of ipsilateral eye closure (lagophthalmos)

• synkinesis

• altered or reduced sense of taste

• hyperacusis

• dry mouth and/or eyes

• mild dysarthria

• synkinesis (late sign in lower motor neurone causes)

An important clinical discriminator between upper and lower motor neurone presentations of facial nerve palsy is that in the former there is sparing of the ipsilateral forehead muscles which allow patients to ipsilaterally wrinkle the forehead, raise the eyebrow, and completely close the eye. This finding is important in trying to localise the lesion and evaluating possible underlying causes, however, can be misleading if the facial palsy is bilateral.

The palsy can be complete or partial with the later carrying a better chance of full recovery. In partial paralysis the lower facial muscles are more prominently affected while loss of taste and sensation to the anterior two-thirds of the tongue occurs more frequently in complete lesions. The House-Brackmann grading system is used to score the severity of presenting facial nerve palsy to help guide treatment and follow up.

Pathology

As above, the pathophysiology of facial nerve palsy depends on the underlying disease and can include all variety of causes summarised in the surgical sieve. Traditionally the preservation of forehead muscles in upper motor neurone lesions has been thought to be due the bilateral innervation of upper facial muscles by the cerebral cortices. However, this may not be supported by the literature ⁴.

Aetiology

Upper motor neurone facial palsy

Causes of upper motor neurone facial palsy include ^5,7:

• stroke

• intracranial tumour

• multiple sclerosis

• syphilis

• HIV

• vasculitides

Lower motor neurone facial palsy

Causes of lower motor neurone facial palsy, including neuromuscular and myopathic causes, include ^6,7:

• idiopathic

  • Bell palsy

• iatrogenic

  • local anaesthetic from dental surgery

  • post-parotidectomy

  • botulinum toxin A administration (e.g. for cosmesis)

  • post-acupuncture haematoma

• infective

  • Ramsay-Hunt syndrome

  • Lyme disease

  • otitis media

  • syphilis

  • tuberculosis

  • HIV

• vascular

  • brainstem infarct

• demyelinating
  • Guillain-Barré syndrome

mononeuropathy

• mononeuropathy

  • diabetes mellitus

  • sarcoidosis

  • amyloidosis

• neoplastic

  • cerebellopontine angle masses

  • posterior fossa tumours

  • parotid gland tumours

  • lymphoma

• trauma

  • skull base fracture (e.g. temporal bone)

  • post-acupuncture haematoma

• autoimmune

  • Sjögren syndrome

  • myasthenia gravis

  • Guillain-Barré syndrome (and variants)

  • neurosarcoidosis

• myopathies

  • ​facioscapulohumeral muscular dystrophy

  • myotonic dystrophy

  • mitochondrial myopathies

• other

  • ​botulism

  • cholesteatoma

  • Melkersson-Rosenthal syndrome

  • myopathies

    Tangier disease

Practical points

• if bilateral consider Guillain-Barré syndrome or or Lyme disease

• if recurrent consider lymphoma, sarcoidosis or Lyme disease

• in children particularly consider Lyme disease and otitis media

See also

• facial nerve

• Bell palsy

• Ramsay-Hunt Syndrome