Facial nerve palsy is the weakness or paralysis of facial muscles due to pathology of the facial nerve.
Course of the facial nerve
| Segment | Description |
|---|---|
| Intracranial | The motor nucleus is situated in the pons and emerges through the cerebellopontine angle to be joined by the nervus intermedius (contains the sensory and autonomic components of the facial nerve). It enters the internal acoustic meatus, which is located in the petrous part of the temporal bone. No branches are given at this point. It travels with the following in the internal acoustic meatus: superior and inferior vestibular nerves, cochlear nerve, labyrinthine artery, and vestibular ganglion |
| Intratemporal | This spans its course from the internal acoustic meatus to its exit through the stylomastoid foramen. It can be further divided into: labyrinthine segment (IAM to geniculate ganglion/first Genu). This is the narrowest portion of the nerve; thus, this is where it is most sensitive to injury. It gives off the greater petrosal nerve. Segment: tympanic segment (geniculate ganglion to second genu); and mastoid segment (second genu to stylomastoid foramen). The nerve to the stapedius and chorda tympani branches leave at this point. |
| Extracranial | Spans from the stylomastoid foramen to its terminal branches in the parotid gland. |
Branches of the facial nerve
| Branch | Innervation |
|---|---|
| Greater petrosal nerve | Parasympathetic innervation to the lacrimal, palatine and nasal glands |
| Chorda tympani | Parasympathetic innervation of the submandibular and sublingual glands. Sensory innervation to the anterior two-thirds of the tongue. |
| Nerve to the stapedius | Motor to stapedius |
| Branches to occipitals, digastric, and stylohyoid muscles | Motor to occipitals, digastric, and stylohyoid muscles |
| Temporal branch | Motor to the frontalis to raise eyebrows |
| Zygomatic branch | Motor to orbicularis oculi to close eyes |
| Buccal branch | Motor to buccinator to puff cheeks |
| Mandibular branch | Motor to show the bottom teeth |
| Cervical branch | Platysma to tense neck |
Causes of facial nerve palsy by anatomic region
| Classification | Cause |
|---|---|
| Central | Brain abscess, pontine gliomas, poliomyelitis, multiple sclerosis, stroke or TIA |
| Intracranial | Acoustic neuroma, meningioma, congenital cholesteatoma, metastasis, meningitis |
| Intratemporal | Idiopathic (Bell’s palsy), Infections (acute and chronic otitis media), trauma (accidental, iatrogenic), neoplasms |
| Extracranial | Malignancy of the parotid, injury to the parotid gland |
| Systemic disease | Diabetes, hypothyroidism, uraemia, leukaemia |
- History
- Physical examination
- Full head and neck examination, including the ears
- Palpation of the parotid gland and face for masses
- Cranial nerve examination with an emphasis on the facial nerve and facial muscle function:
- Wrinkling of the forehead, keeping eyes closed against resistance to opening, smiling to show teeth, and frowning
- Blink test
- Tapping the labella should stimulate blinking
- Schirmer test
- A test for lacrimation using blotting paper
- Stapedial test
- Tests sensitivity to loud sounds. This is done via tympanometry
- Salivary test
- The salivation rate is assessed from a submandibular duct after stimulation with a 6% citric acid solution
- Taste test using salt, sweet, sour, and bitter tastes along the lateral aspects of the anterior two-thirds of the tongue
- Investigations
- Nerve conduction studies
- Complete Blood Count
- C-reactive protein
- UECs
- VZV antibody titres
- Immunoglobulin titres
- Elevated in Lyme disease
- Imaging studies (Ultrasound, CT or MRI) for trauma or malignancy
- Audiogram if there is hearing loss
- Treatment
- Eye care
- Artificial tears
- Taping the eye closed at night
- Facial muscle therapy and massage
- Bell’s palsy is treated with steroids (prednisolone) and analgesics
- Ramsay Hunt syndrome is treated with steroids (prednisolone), analgesia, and antivirals (acyclovir)
- Surgery
- Facial nerve decompression
- Facial nerve repair and grafting
- Eye care
- Poor prognostic factors
- Age >50 years
- Complete palsy
- Loss of acoustic reflex
- Ramsay Hunt Syndrome
- Poor electrophysiological test results
- No signs of recovery after three weeks of treatment
- Associated comorbidities such as hypertension, diabetes, and pregnancy
- Complications
- Exposure keratitis
- Disfigurement
- Hemifacial spasm
- Synkinesis – the involuntary contraction of facial muscles occurring simultaneously with a voluntary movement, typically after facial nerve palsy has recovered
House Brackman grading system – Normal Function to complete paralysis
| Grade | Description |
|---|---|
| I | Normal, symmetrical function |
| II | Slight weakness is obvious on close inspection, slight asymmetry of the smile |
| III | Obvious, non-disfiguring weakness, complete eye closure |
| IV | Obvious, disfiguring weakness, inability to completely close eyes, and lift eyebrows. Normal facial symmetry at rest |
| V | Barely perceptible facial motion; asymmetry at rest |
| VI | Complete paralysis |
| Grade | Function level | Symmetry at Rest | Eye(s) | Mouth | Forehead |
|---|---|---|---|---|---|
| I | Normal | Normal | Normal | Normal | Normal |
| II | Mild | Normal | Easy and complete closure | Slightly asymmetrical | Reasonable function |
| III | Moderate | Normal | With effort, complete closure | Slightly affected with effort | Slight-to moderate movement |
| IV | Moderately severe | Normal | Incomplete closure | Asymmetrical with maximum effort | None |
| V | Severe | Asymmetry | Incomplete closure | Minimal movement | None |
| VI | Total paralysis | Total paralysis | Total paralysis | Total paralysis | Total paralysis |