This is a UKMLA-centred history guide on facial weakness.

Introduction

Facial paralysis is the total weakness of facial muscles due to dysfunction of the facial nerve (CNVII). The pattern of weakness depends on where the upper motor neuron (UMN) or lower motor neuron (LMN) of the facial nerve is affected. An UMN lesion spares the forehead (as it receives supply from both hemispheres), manifesting as contralateral mouth weakness. A LMN lesion causes ipsilateral weakness of both the forehead and the mouth. Aetiology of facial paralysis can be categorised into:

• LMN lesions (aka peripheral) causes:
  • Bell’s Palsy (most common cause)
  • Ramsay Hunt syndrome
  • Trauma/surgery e.g. parotid gland surgery
  • Infections e.g. otitis media, mastoiditis
  • Tumours e.g. acoustic neuroma
  • Guillain Barre syndrome (GBS)

• UMN lesions (aka central) causes:
  • Stroke (most common cause)
  • Multiple sclerosis
  • Brain tumours
  • Infections e.g. encephalitis
  • Traumatic brain injury
  • Systemic causes such as diabetes, sarcoidosis, amyloidosis, etc.

Common OSCE Scenarios

Presenting Complaint

Site

• Unilateral
  • Mouth involved and forehead spared → UMN lesion e.g. stroke
  • Mouth and forehead involved → LMN lesion e.g. Bell’s palsy
• Bilateral → systemic causes e.g. sarcoidosis

Onset

• Sudden → vascular causes e.g. stroke and TIA.
• Chronic → brain tumour, motor neurone disease, multiple sclerosis

Associated symptoms

• Changes in vision and hearing → multiple sclerosis, stroke, vestibular schwannoma, otitis media with mastoiditis
  • If the vision changes first → multiple sclerosis and stroke are more likely
  • If the hearing changes first → vestibular schwannoma and otitis media with mastoiditis
• Changes in sensation → stroke and multiple sclerosis
• Fits, faints and funny turns → stroke or seizure
• Changes in speech and swallow → helps to indicate if patient will need speech and language therapy in the future

Background

Past medical history

• Previous infection and fevers → Ramsay Hunt syndrome, meningitis, encephalitis and otitis media causing mastoiditis
• B symptoms (fatigue, lethargy, anorexia, weight loss and night sweats)→ brain malignancy
• Previous history of falls and trauma → directly damaging facial muscles and nerve
• History of neurological disease e.g. Bell’s palsy, motor neurone disease and multiple sclerosis, primary brain tumour
• Hypertension, high cholesterol, diabetes, ischaemic heart disease, and previous cerebrovascular disease → increased risk of stroke
• Immunocompromised → CNS lymphoma or severe manifestation of viral infections e.g. HIV/EBV which can cause facial paralysis.
• Neurofibromatosis type 2 → vestibular schwannoma/acoustic neuroma
• Cancer → cerebral metastases

Family History

• Stroke at a young age → arteriovenous malformation, cerebral venous sinus thrombosis, thrombophilias
• Neurological conditions → Bell’s palsy, motor neurone disease, multiple sclerosis and neurofibromatosis

Drug and Social History

• Blood thinners e.g. apixaban → increase risk of intracranial bleeding
• Recreational drug use e.g. cocaine can cause facial paralysis
• Travel history → leprosy and Lyme disease
• Lack of exercise and poor diet → increases risk of diabetes, hypertension, cardiovascular and cerebrovascular disease.

Examination

A full neurological examination is crucial in anyone presenting with weakness. Excluding stroke is the utmost priority, as missing it can be fatal. As stroke is an upper motor neuron (UMN) lesion, look for UMN signs e.g. hypertonia. Then identify the pattern of weakness:

• Unable to raise left eyebrow and cheek → Bell’s palsy of left LMN of CNVII
• Unable to raise left cheek but eyebrow spared → Right-sided stroke
• Ptosis (droopy eyelid) → 3rd nerve palsy

Sensory loss is more likely to present with stroke/multiple sclerosis/polyneuropathy. Assess cerebellar function by doing tests of coordination (e.g. nose-to-finger test) and gait. Presence of DANISH signs suggests cerebellar disease:

• D = dysmetria/dysdiadochokinesia
• A = ataxia
• N = nystagmus 
• I = intentional tremor
• S = slurred/scanning speech
• H = hypotonia

References
 
1. Facial Palsy UK: https://www.facialpalsy.org.uk/causesanddiagnoses/list/ [Accessed 12/8/24]

2. Stroke and TIA NICE CKS: https://cks.nice.org.uk/topics/stroke-tia/ [Accessed 22/08/24]

3. BMJ Best Practice: https://bestpractice.bmj.com/topics/en-gb/118?q=Bell%27s%20palsy&c=suggested [Accessed 22/08/24]

Author – Bharneedharan Surendaran  

Editor – Dr Karthikeyan Sivaganesh

Last updated 23/01/2026