Differentials
Bell’s palsy
SIGNS / SYMPTOMS
Most common cause of sudden-onset unilateral facial palsy.
Absence of vesicular ear rash, vertigo, or hearing loss.
Pain in Bell’s palsy is typically less severe than that in Ramsay Hunt syndrome.
INVESTIGATIONS
Clinical diagnosis.
Malignant facial nerve tumour
SIGNS / SYMPTOMS
Gradual onset facial paralysis.
Prior history of cutaneous squamous cell carcinoma of ipsilateral face/scalp.
INVESTIGATIONS
MRI head and neck with contrast: malignancy in the facial nerve course.
CT temporal bone with or without contrast: widened canal suggests facial schwannoma.
Benign facial nerve tumour (e.g., facial nerve schwannoma)
SIGNS / SYMPTOMS
Waxing and waning or slowly progressive facial palsy.
May demonstrate uneven distribution of weakness across facial zones, with elements of synkinesis and fasciculations.
INVESTIGATIONS
Contrast-enhanced MRI of the course of the facial nerve, with fine-cut CT of the temporal bones: mass lesion.
Cerebrovascular accident
SIGNS / SYMPTOMS
Presence of central nervous system deficits, such as unilateral weakness or sensory changes, aphasia, ataxia.
INVESTIGATIONS
MRI or CT of the head shows evidence of cerebral infarct or haemorrhage.
Blunt force trauma/laceration to face or temporal bone
SIGNS / SYMPTOMS
Recent history of blunt force trauma to the cranium (i.e., temporal bone fracture) or penetrating trauma involving the course of the facial nerve.
INVESTIGATIONS
CT head (CT temporal bone preferred): transverse temporal bone fracture, often involving the otic capsule.
Idiopathic orofacial granulomatosis (Melkersson-Rosenthal syndrome)
SIGNS / SYMPTOMS
Classical presentation is a triad of recurrent unilateral facial swelling, facial palsy, and fissured tongue (lingua plicata).[16]
INVESTIGATIONS
Clinical diagnosis.
Malignant otitis externa
SIGNS / SYMPTOMS
Uncontrolled diabetes or underlying immunosuppression.
History of ear pain, chronic ear drainage, and other cranial nerve deficits.
INVESTIGATIONS
Physical examination: granulation tissue at the bony cartilaginous junction in the ear canal.
Nuclear bone scan (MRI with Technetium-99 radiotracer): enhancement along the lateral skull base.
Guillain-Barre syndrome
SIGNS / SYMPTOMS
Typically bilateral presentation.
Involvement of upper and lower extremities, usually an ascending paralysis from the toes and fingers moving towards the torso.
May have facial involvement usually as later sequela.
INVESTIGATIONS
Lumbar puncture: elevated cerebrospinal fluid protein.
Electroneurography (ENoG): delayed nerve conduction across involved structures.
Cholesteatoma
SIGNS / SYMPTOMS
History of recurrent ear infections and ear discharge. Remote history of ear trauma or prior ear surgery.
Vertigo is associated with labyrinthine fistula.
INVESTIGATIONS
CT scan of the petrous temporal bones: soft tissue density in the middle ear and possible ossicular erosion. May show dehiscent facial nerve in tympanic or mastoid segment, with or without erosion of the horizontal semicircular canal and resultant labyrinthine fistula.
Complicated otitis media
SIGNS / SYMPTOMS
On otoscopy there is perforation of the pars tensa but no evidence of cholesteatoma.
INVESTIGATIONS
Diagnosis is clinical.
Lyme disease
SIGNS / SYMPTOMS
Skin rash (erythema migrans or other), frontal headache, fever, malaise, fatigue, myalgia, arthralgia, known tick exposure, or recent travel to Lyme disease-endemic region.
INVESTIGATIONS
Elevated immunoglobulins (IgM and/or IgG) to Borrelia burgdorferi by enzyme-linked immunosorbent assay (ELISA) or indirect fluorescent antibody titres are demonstrated.
Western blot is then performed for confirmation.
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