From the Guidelines
Bell's palsy is a diagnosis of exclusion, characterized by acute unilateral facial nerve paresis or paralysis with onset in less than 72 hours and without an identifiable cause.
Definition and Diagnosis
- It is defined as acute unilateral facial nerve paresis or paralysis with onset in less than 72 hours and without an identifiable cause 1.
- The diagnosis of Bell's palsy is made by excluding other causes of facial paresis or paralysis, such as neoplasms, trauma, congenital or syndromic problems, specific infectious agents, or postsurgical facial paresis or paralysis 1.
- A comprehensive history and physical examination are essential to detect neurologic, otologic, oncologic, inflammatory, or infectious causes, as well as cerebello-pontine angle pathology or vascular insufficiencies 1.
Clinical Features
- Patients with Bell's palsy may experience dryness of the eye or mouth, taste disturbance or loss, hyperacusis, and sagging of the eyelid or corner of the mouth 1.
- Ipsilateral pain around the ear or face is not an infrequent presenting symptom 1.
- The condition can cause significant temporary oral incompetence and an inability to close the eyelid, leading to potential eye injury 1.
Treatment and Prognosis
- Oral corticosteroids are recommended for patients 16 years and older with new-onset Bell's palsy to decrease recovery time and improve facial nerve functional recovery 1.
- Most patients with Bell's palsy show some recovery without intervention within 2 to 3 weeks after onset of symptoms and completely recover within 3 to 4 months 1.
- Even without treatment, facial function is completely restored in approximately 70% of Bell's palsy patients with complete paralysis within 6 months and as high as 94% of patients with incomplete paralysis 1.
From the Research
Definition and Characteristics
- Bell's palsy, also known as idiopathic facial palsy, is a common cranial neuropathy that leads to facial muscle paresis or complete paralysis on one side of the face 2, 3, 4, 5, 6.
- It is characterized by sudden onset and may progress over 48 hours, resulting from facial nerve dysfunction due to trauma or inflammation of the 7th cranial nerve or its branches 2.
- Both sexes are equally affected, and although no age is immune, its incidence rises with increasing age, with a higher risk in diabetics, hypertensives, pregnant women, obese individuals, and people with upper respiratory tract infections 2.
Etiology and Pathogenesis
- The exact etiology of Bell's palsy is unknown, but it is considered chiefly idiopathic and is diagnosed by the exclusion of other causes 2, 6.
- Immune, infective, and ischemic mechanisms are potential contributors to the development of Bell's palsy, with some studies suggesting a possible role of herpes simplex virus type 1 3, 5.
- Inflammation of the facial nerve at the geniculate ganglion is also believed to be a possible cause of Bell's palsy 4.
Clinical Features and Diagnosis
- The most alarming symptom of Bell's palsy is unilateral facial weakness, which can result in the inability to close the eyelids, smile, or whistle 4.
- Symptoms typically peak in the first week and then gradually resolve over three weeks to three months 5.
- Laboratory evaluation may include testing for diabetes mellitus and Lyme disease, and electromyography can be used as a prognostic marker for defective healing 5, 6.
Treatment and Prognosis
- Approximately 70-80% of patients will recover spontaneously, but treatment with steroids, such as prednisone, can reduce the time to full recovery and increase the likelihood of complete recuperation 2, 5, 6.
- Antiviral drugs may be beneficial in select cases of severe Bell's palsy, and physiotherapy, targeted botulinum toxin injection, and selective surgical intervention can be used to address aesthetic, functional, and psychological considerations 3, 6.
- Early diagnosis and treatment are crucial to improve the patient's function and esthetics, and to reduce the risk of residual paresis and long-term disability 2, 4.