Facial Nerve Palsy: Causes

Pathogenesis (development of disease)

Facial nerve palsy represents paralysis of the muscles innervated by the facial nerve, the facial nerve. The facial nerve is the VII cranial nerve. It is involved in the following processes, among others:

  • Innervation of the facial muscles
  • Sensation of taste [chorda tympani].
  • Salivary gland secretion: submandibular gland and sublingual gland [chorda tympani].
  • Hearing [stapedial nerve]
  • Lacrimal secretion [petrosal major nerve]

The pathogenesis varies in depending on the etiology of the disease. Possible causes of central facial paresis include intracranial hemorrhage (bleeding within the skull; parenchymal, subarachnoid, sub- and epidural, and supra- and infratentorial hemorrhage)/intracerebral hemorrhage (ICB; cerebral hemorrhage), apoplexy (stroke), or tumor. In about 60-75% percent of cases of peripheral facial palsy, the cause is unknown – this is called idiopathic facial palsy, also known as Bell’s palsy. Possible causes of peripheral nerve palsy include reactivation of a herpes simplex virus infection (HSV type 1) and cell-mediated autoimmune inflammation.

Etiology (cause) of peripheral facial nerve palsy

Biographic causes

  • Hormonal factors – pregnancy and puerperium have a predisposing effect; during pregnancy, the risk of developing idiopathic peripheral facial nerve palsy is increased threefold

Disease-related causes.

Congenital malformations, deformities, and chromosomal abnormalities (Q00-Q99).

  • Möbius nuclear aplasia – congenital disorder leading to other cranial nerve deficits in addition to facial nerve palsy (mode of inheritance: sporadic occurrence).

Certain conditions originating in the perinatal period (P00-P96).

  • Obstetric paralysis (facial nerve injury)-particularly increased risk in forceps delivery (lat. Forceps)

Blood, blood-forming organs – immune system (D50-D90).

Endocrine, nutritional and metabolic diseases (E00-E90).

Cardiovascular system (I00-I99).

  • Apoplexy – lesion of the contralateral cortex or corticobulbar tracts after ischemic infarction.
  • Aneurysm (wall bulge) of the vertebral artery (vertebral artery)
  • Ischemia-related (due toinfarction, hemorrhage, tumor) – caused by a reduction in the supply of nutrients to the nerve.

Infectious and parasitic diseases (A00-B99).

  • Infections:
    • Herpes simplex virus-1 (HSV-1).
    • Varicella-zoster virus (VZV; also varicella-zoster virus – suspected zoster oticus, with redness, edema (swelling), blistering in the ear area or on the eardrum, and otalgia (pain in the ear region) being indicative
    • Rare viral infections: EBV, CMV, HPV-B19, HIV, enteroviruses, mumps virus, measles virus, rubella virus, adenovirus and influenza virus.
    • Lyme disease (bacteria from the group of Borrelia (spirochetes)).
    • Rare bacterial infections: Diphtheria (Corynebacterium diphtheriae), ehrlichiosis (bacterium Ehrlichia canis), leptospires, M. pneumoniae, Bartonella henselae, Rickettsia (bacteria of the genus Rickettsia; e.g. Mediterranean region).

Musculoskeletal system and connective tissue (M00-M99).

  • Granulomatosis with polyangiitis (GPA), formerly Wegener’s granulomatosis – necrotizing (tissue dying) vasculitis (vascular inflammation) of the small to medium-sized vessels (small-vessel vasculitides), which is associated with granuloma formation (nodule formation) in the upper respiratory tract (nose, sinuses, middle ear, oropharynx) as well as the lower respiratory tract (lungs)
  • Sjögren’s syndrome (group of sicca syndromes) – autoimmune disease from the group of collagenoses, which leads to a chronic inflammatory disease of the exocrine glands, most often the salivary and lacrimal glands; typical sequelae or complications of sicca syndrome are:
    • Keratoconjunctivitis sicca (dry eye syndrome) due to lack of wetting of the cornea and conjunctiva with tear fluid.
    • Increased susceptibility to caries due to xerostomia (dry mouth) due to decreased salivary secretion.
    • Rhinitis sicca (dry nasal mucous membranes), hoarseness and chronic cough irritation and impaired sexual function due to disruption of mucous gland production of the respiratory tract and genital organs.

Neoplasms – tumor diseases (C00-D48).

  • Acoustic neuroma (AKN) – benign tumor arising from Schwann’s cells of the vestibular portion of the VIII. Cranial Nerve, the auditory and vestibular nerves (vestibulocochlear nerve), and is located in the cerebellopontine angle or internal auditory canal. Acoustic neuroma is the most common cerebellopontine angle tumor. More than 95% of all AKNs are unilateral. In contrast, in the presence of neurofibromatosis type 2, acoustic neuroma typically occurs bilaterally.
  • Malignant parotid tumors – neoplasms of the parotid gland.
  • Meningiomas, glomus tumor – originating from the cerebellopontine angle, often further cranial nerve failures.
  • Tumors (neoplasms) at the base of the skull, brainstem or cerebellopontine angle.
  • Tympanic fascial schwannoma (affecting the tympanic cavity (tympanum) or the tympanic membrane (membrana tympani)); schwannomas (see below acoustic neuroma) of the facial nerve are rare with an incidence of 0.38%; often affect multiple segments of the facial process

Ears – mastoid process (H60-H95).

  • Cholesteatoma – ingrowth of multilayered keratinizing squamous epithelium into the middle ear with subsequent chronic purulent inflammation.
  • Mastoiditis (mastoid process inflammation).
  • Otitis media (inflammation of the middle ear)
  • Parotitis (parotid gland inflammation)

Psyche – nervous system (F00-F99; G00-G99)

  • Guillain-Barré syndrome (GBS; synonyms: Idiopathic polyradiculoneuritis, Landry-Guillain-Barré-Strohl syndrome); two courses: acute inflammatory demyelinating polyneuropathy or chronic inflammatory demyelinating polyneuropathy (peripheral nervous system disease); idiopathic polyneuritis (multiple nerve disease) of spinal nerve roots and peripheral nerves with ascending paralysis and pain; usually occurs after infection
  • Meningitis (meningitis).
  • Multiple sclerosis (MS)
  • Polyneuritis – inflammation of multiple nerves.
  • Progressive bulbar paralysis – disease in which there is a failure of motor cranial nerve nuclei and belongs to the group of spinal muscular atrophies (muscle atrophy caused by a progressive loss of motor neurons in the anterior horn of the spinal cord).
  • Syringobulbia – disease of the medulla oblongata associated with its destruction.

Pregnancy, childbirth and puerperium (O00-O99).

  • Pregnancy and puerperium have a predisposing effect; during pregnancy, the risk of disease for idiopathic peripheral facial nerve palsy is increased threefold

Injuries, poisonings, and other sequelae of external causes (S00-T98).

  • Fractures of the temporal bone
  • Basal skull fracture
  • Traumatic brain injury (TBI)
  • Trauma-related – after injuries (in infancy: birth trauma).
  • Poisoning, unspecified

Other causes

  • Idiopathic – a cause is not found (60-80% of cases: idiopathic facial paresis or Bell’s palsy).
  • After surgery on the ear or especially on the parotid gland (parotid gland); after surgical removal of benign parotid tumors (pleomorphic adenomas or Warthin tumors), 40.2% of patients had facial nerve paresis on the first day after surgery; at two weeks postoperatively, 28.3%, at six months, 3.9%, and at one year, 1.6% of patients.

Etiology of central facial nerve palsy

Disease-related causes

Cardiovascular (I00-I99).

  • Angioma – tumor-like vascular neoplasm.
  • Apoplexy (stroke)
  • Cerebral hemorrhage, unspecified

Neoplasms – tumor diseases (C00-D48).

  • Brain tumors, unspecified

Psyche – nervous system (F00-F99; G00-G99).

  • Pseudobulbar paralysis – disease caused by a lesion of the tractus corticobulbaris (corticonuclearis).