Learning Objectives
- Bell’s palsy shows symptoms of upper and lower unilateral facial weakness
- Bell’s palsy be treated with steroid medication near the time of onset
- Most cases of Bell’s palsy resolve over time
History
ER, a 48 year old lady, reports that she awoke with weakness on the right side of the face about 14 days ago. When she looked in the mirror, she said the right corner of her mouth dropped downwards. Her husband told her she could not close her right eye. Her smile was impaired and she could not pucker her lips or make a whistling noise. There was no change with hearing or taste. There was no alteration of the vision or the facial sensation. There was no pain, headache or rash. The symptoms have continued to bother her, although she is beginning to notice some movement of her facial expression.
She has no history of medical allergies. Her home medications are glipizide, metformin and lisinopril.
She has a past medical history of obesity, hypertension, and diabetes mellitus type II.
There is a family history of diabetes mellitus and renal cell cancer.
Review of systems indicates fatigue, but otherwise, a ten system review was negative.
Examination
Blood pressure was 128/77. Pulse was 74. She is a pleasant overweight lady. Her language and attention are normal. Carotid auscultation reveals no bruits on either side. Pupillary and funduscopic exams are normal. There is obvious weakness of facial expression on the right side. She cannot move the eyebrow on the right, and when she forcibly closes her eyes, the right eyelid does not close completely, and the upward deviating eye can be seen. The right corner of the mouth moves slightly when she tries to smile or to frown. Eye movements are normal in all directions. Hearing is normal. Facial sensation to pin prick is normal. Gag response is normal on both sides, and palate and tongue movements are normal. Sternocleidomastoid and trapezius movements are normal. Strength is normal in the arms and legs. Deep tendon reflexes are depressed in the biceps, patella and absent in the Achilles on both sides. Toes are downgoing. She has normal sensation to pin prick in the feet, the lower legs and in both hands. She has normal heel knee shin movements and a normal gait.
The localization of unilateral facial weakness is the facial nerve, prior to division into upper and lower branches. A differential diagnosis of a unilateral facial weakness is trauma, Bell’s palsy and stroke. Facial weakness may also be caused by changes within the motor nerve fibers of the corticospinal tract or the motor nucleus of the facial nerve, but these tend to cause a lower facial weakness only (affecting the mouth, not the eye), because the upper face has significant redundant innervation from both sides of the brain.
When children are delivered by forceps, transient facial nerve palsy is not uncommon. Facial surgeries sometimes damage the facial nerve, although surgeons are very careful to avoid this. Traumatic injury such as an auto accident may cause facial nerve trauma. A neoplastic lesion of the facial nerve can also cause weakness, but this tends to have a progressive course.
A stroke affecting the brainstem can damage the facial nerve. This tends to be associated with other symptoms, because the brainstem is packed with so many vital structures, damage to one small internal structure is rare. For example, a stroke affecting the brain stem may damage the facial nerve root, as well as cause weakness to the contralateral side of the body or numbness to pin prick in the body or in the face, by damaging the spinothalamic tract, corticospinal tract, or the trigeminothalamic tract, which are near the facial nucleus and root of the facial nerve.
Bell’s palsy is perhaps the most common cause of unilateral facial weakness. It has been felt that this is associated with viral infections, and at times, Lyme disease. Most cases of Bell’s palsy are considered to be idiopathic in nature. They are almost always unilateral, but 1-2% of cases are bilateral.
Bell’s palsy is a clinical diagnosis, and MRI of the brain is normal in this case. At times, contrast enhancement may be found in a small segment of the proximal facial nerve. The MRI exam should show no evidence neoplastic disease, entrapment or other inflammation. In most cases, the neurological exam is sufficient to diagnose this disorder. MRI testing or laboratory testing tend to be reserved for exceptional cases.
Treatment
Patients diagnosed with Bell’s palsy may respond to antiviral medication or corticosteroids. The medical literature does not strongly support antiviral treatment, but it seems patients and clinicians are insistent on providing whatever interventions they can. If the symptoms have occurred longer than 72 hours, there is no evidence medical treatment is helpful.
Protection of the cornea is probably the most important treatment in Bell’s palsy. With peripheral causes of facial weakness, the eye cannot close entirely, resulting in injuries and drying of the surface of the eye. Eye patching, lubrication and keeping the eye closed during sleep are important remedies that prevent loss of vision on the affected side.
Recovery may occur over days or months, and is often complete. In most cases, recovery is gradual. Patients should be reassured as they see signs of recovery. These may occur even without treatment. In limited cases, such as when facial weakness is severe, incomplete recovery may result.
Review Questions
- A patient asks to see you at clinic urgently. They believe they have Bell’s palsy. You expect to find on examination:
a. unilateral facial numbness
b. unilateral ptosis
c. unilateral weakness of mastication
d. unilateral upper and lower facial weakness
e. unilateral lower facial weakness - You agree with the patient that the diagnosis is Bell’s palsy. You consider treating them with corticosteroids (prednisone). You decline to treat them however because:
a. the symptoms are older than 72 hours
b. steroids may cause many side effects, including hyperglycemia
c. steroids are not indicated for treatment of Bell’s palsy
d. steroids may exacerbate a viral infection that causes Bell’s palsy, and should be used with an antiviral agent
e. there are better treatments for Bell’s palsy - The patient agrees with your plan. They ask what the forecast for this condition is. You tell them:
a. Bell’s palsy always improves in two days
b. The facial symptoms should improve in two weeks
c. Many patients gradually improve over time
d. the symptoms will only improve if they are treated
e. The symptoms will not improve