Bell’s Palsy

Dr. Ali Tahir

Facial nerve

• Sir Charles Bell (1774-1842) first studied the facial nerve anatomy

• A mixed nerve, with motor, sensory, special sensory & secretomotor fibers

• Motor muscles of facial expression• Sensory concha and retro-auricular skin• Special Sensory taste sensation• Secretomotor lacrimal, sublingual,

submandibular glands & some in nose & palate

Branches

• Greater superficial petrosal nerve:• Nerve to stapedius:• Chorda tympani:• Communicating branch:• Posterior auricular nerve:• Muscular branches:• Peripheral branches: “Pes anserinus”

Bell’s palsy

Bells palsy is an acute lower motor neuron paralysis of the face

• Idiopathic• Diagnosis of exclusion• 10-30 per 100,000• Usually young adults• Peripheral neuropathy

Pathophysiology

• Exact cause unknown• Inflammation/oedema of facial nerve with

demyelination, usually in stylomastoid canal• May be immunologically mediated &

associated with infection, usually HSV• Other causative micro-organisms can be VZV,

EBV, CMV, HHV-6, HIV, HTLV-1 or bacterial otitis media, lyme disease

• Vascular ischemia

Predisposing factors

• Pregnancy• Hypertension• Diabetes• Lymphoma• Hereditary

Clinical Features

• Twitching, weakness, paralysis of face, dryness of eyes/mouth, disturbance of taste/hearing

• Acute onset• Generally Unilateral• Acute onset < 48 hours• Paralysis of upper and lower face• Diminished blinking• Dryness, erosion, ulceration of cornea &

potential loss of the eye

Clinical features

• occasionally:– Pain in ear or jaw may precede the palsy– Facial numbness– If lesion is proximal to stylomastoid canal, there

may be hyperacusis, loss of taste/lacrimation– Upto 10% have family history– Upto 10% have recurrent episodes

Bell’s palsy

Bell’s palsy

Diagnosis

• Exclude other causes of facial palsy such as – Stroke– Trauma to facial nerve– Tumours affecting the facial nerve– Inflammatory disorder affecting the facial n.• Multiple sclerosis• Connective tissue disease• Sarcoidosis• Melkersson Roenthal Syndrome

Examination

• A full neurological examination to exclude a stroke or lesions involving other cranial nerves

• Examination of facial nerve– Corneal reflex– Close eyes against resistance– Raise eyebrows– Raise lips to show teeth– Try to whistle

Examination

• Ear & mouth examination to rule out Ramsay-Hunt Syndrome which causes lesions in the palate & ipsilateral ear & facia palsy

• Ear examination for any discharge or middle ear infections

Investigations• Test for degree of nerve damage – Facial nerve stimulation– Needle electro-myography

• Test for loss of hearing– Pure tone audiometry

• Test for loss of taste• Test for balance• Schirmer’s test• CT/MRI to rule out any tumour• B.P• Blood complete

Investigations

• Blood sugar• Tests for HSV, HIV or other viral infections• Serum ACE to rule out sarcoidosis• Serum ANA to exclude connective tissue

disease• ELIZA to rule out lyme disease

Management

• Observation• Upto 85% improve spontaneously within a few

weeks• Medical treatment– Steroid such as prednisolone (80-90% recovery)– Anti-viral agents (aciclovir)

• Facial rehabilitaion