Anatomy Pelvis Head Neck · Year 1 · from Anatomy Pelvis Head Neck
Case 1: Bell's Palsy
Patient Demographics
- Age: 38 years old
- Sex: Female
- Occupation: Marketing executive
Chief Complaint
Sudden onset of right-sided facial droop and inability to close the right eye, noticed upon waking this morning.
History of Present Illness
The patient went to bed feeling well and awoke this morning to find the right side of her face drooping. She noticed that she could not fully close her right eye, her smile was asymmetric, and she was drooling from the right corner of her mouth. She reports that food and drink spill from the right side of her mouth. She also notes that sounds seem louder in her right ear (hyperacusis) and that she has diminished taste sensation on the right side of her tongue. She denies hearing loss, vertigo, limb weakness, numbness, speech difficulty, or vision changes. She had a mild upper respiratory infection approximately 1 week ago. She has no history of diabetes, recent travel, or tick exposure.
Physical Examination
- Vitals: Within normal limits
- Neurological examination:
- Facial nerve (CN VII): Right-sided facial weakness involving BOTH the upper and lower face; unable to wrinkle forehead on right, unable to close right eye against resistance (Bell's phenomenon present - eye rolls upward on attempted closure), asymmetric smile with right-sided droop, unable to puff out right cheek
- Taste: Diminished on anterior two-thirds of tongue on right
- Other cranial nerves: Normal, including hearing
- Motor/Sensory: Normal strength and sensation in all limbs
- Ear examination: External auditory canal and tympanic membrane normal; no vesicles (rules out Ramsay Hunt syndrome)
- Eye examination: Incomplete right eyelid closure; conjunctiva mildly injected due to exposure
Clinical Image
Photograph demonstrating typical facial appearance in Bell's palsy with inability to close the eye and asymmetric facial droop.
Image Source: Wikimedia Commons - Bellspalsy.jpg, CC BY-SA 3.0
Diagnosis
Bell's Palsy (idiopathic facial nerve paralysis)
Anatomical Correlation
The facial nerve (CN VII) has a complex course with multiple segments. After exiting the brainstem at the cerebellopontine angle, it enters the internal acoustic meatus and traverses the facial canal within the petrous temporal bone. Within the canal, it gives off the greater petrosal nerve (carrying parasympathetic fibers to the lacrimal gland), the nerve to stapedius (which dampens loud sounds), and the chorda tympani (carrying taste fibers from the anterior two-thirds of the tongue). The nerve exits through the stylomastoid foramen and enters the parotid gland, where it divides into five terminal branches (temporal, zygomatic, buccal, marginal mandibular, cervical) that innervate the muscles of facial expression. Bell's palsy is thought to result from viral inflammation and edema of the facial nerve within the narrow confines of the facial canal, causing compression and ischemia. The characteristic finding is a lower motor neuron (peripheral) pattern of facial weakness affecting ALL muscles on the ipsilateral side, including the forehead (frontalis). This distinguishes it from an upper motor neuron lesion (such as stroke), where the forehead is spared because the frontalis muscle receives bilateral cortical input. The involvement of taste (chorda tympani) and hyperacusis (stapedius nerve) indicates that the lesion is within the facial canal, proximal to where these branches arise.
Treatment
- Corticosteroids: Prednisone 60-80 mg daily for 7 days, then taper (improves outcomes if started within 72 hours)
- Antivirals: Consider adding valacyclovir if severe; evidence is less robust than for steroids
- Eye protection: Critical to prevent exposure keratopathy
- Artificial tears during the day
- Lubricating ointment at night
- Tape eyelid closed during sleep
- Consider moisture chamber or eye patch
- Physical therapy: Facial exercises may help recovery
- Prognosis: 70-85% recover completely within 3-6 months; incomplete recovery more likely in older patients, those with complete paralysis, or delayed treatment