Anatomy Pelvis Head Neck · Year 1 · from Anatomy Pelvis Head Neck
Case 1: Bell's Palsy (Peripheral Facial Nerve Palsy)
Patient Demographics
- Age: 35 years old
- Sex: Female
- Occupation: Elementary school teacher
Chief Complaint
Sudden onset of facial drooping on the right side since this morning.
History of Present Illness
The patient woke up this morning and noticed that the right side of her face felt "heavy" and was not moving properly. She had difficulty closing her right eye and noticed drooling from the right corner of her mouth while brushing her teeth. She reports that food feels different in her mouth, and sounds seem louder in her right ear. Two days ago, she experienced mild pain behind her right ear. She has no history of recent viral illness, though there has been increased stress at work. She denies headache, limb weakness, speech difficulty, or vision changes.
Physical Examination
- Vitals: Within normal limits
- Face at rest: Flattening of the right nasolabial fold, drooping of the right corner of the mouth
- Forehead: Unable to wrinkle forehead or raise eyebrow on the right (entire right side affected)
- Eyes: Unable to close right eye completely; Bell's phenomenon present (eye rolls upward on attempted closure)
- Mouth: Unable to smile symmetrically; drooling from right side; unable to puff cheeks
- Taste: Decreased taste on anterior two-thirds of tongue on the right
- Hearing: Hyperacusis (sounds louder) in right ear
- Other cranial nerves: Normal
- Limbs: Normal strength and coordination
Clinical Image
Clinical photograph demonstrating complete right-sided facial paralysis in Bell's palsy, with inability to close the right eye, flatten the forehead, or raise the eyebrow on the affected side.
Image Source: Wikimedia Commons - File:Bellspalsy.JPG, licensed under CC BY-SA 3.0
Diagnosis
Bell's palsy (idiopathic peripheral facial nerve palsy) affecting the entire right facial nerve.
Anatomical Correlation
Bell's palsy is a lower motor neuron lesion of the facial nerve (CN VII), and the critical distinguishing feature is involvement of the forehead. The facial nerve nucleus receives bilateral input from the cortex for the upper face but only contralateral input for the lower face. Therefore, a stroke (upper motor neuron lesion) spares the forehead because the ipsilateral corticobulbar fibers remain intact. In Bell's palsy, the nerve is affected at or distal to the nucleus, paralyzing all ipsilateral facial muscles including the frontalis. The facial nerve has several branches in its course: the greater petrosal nerve (parasympathetic to lacrimal gland), nerve to stapedius (dampens loud sounds), and chorda tympani (taste to anterior two-thirds of tongue, parasympathetic to submandibular and sublingual glands). The presence of hyperacusis (due to stapedius paralysis) and taste loss indicates the lesion is proximal to the branch points, likely within the facial canal. The facial nerve exits the skull through the stylomastoid foramen and then divides within the parotid gland into five terminal branches (temporal, zygomatic, buccal, marginal mandibular, cervical) remembered by "To Zanzibar By Motor Car."
Treatment
- Corticosteroids: Prednisone 60-80 mg daily for 7 days with taper; improves recovery rate
- Antiviral therapy: Valacyclovir may be added, especially if herpes simplex reactivation suspected
- Eye protection: Artificial tears, lubricating ointment at night, tape eyelid closed during sleep to prevent exposure keratitis
- Physical therapy: Facial exercises to maintain muscle tone
- Prognosis: 80-90% recover completely within 3-6 months