What causes recurrent Bell's (Bell's) palsy?

Causes of Recurrent Bell's Palsy

Critical Diagnostic Principle

When facial paralysis recurs, it is no longer considered idiopathic Bell's palsy and requires identification of an underlying etiology. 1

The American Academy of Otolaryngology-Head and Neck Surgery explicitly states that Bell's palsy is defined as an acute condition without identifiable cause occurring for the first time, and any recurrence mandates a diagnostic workup to find the underlying cause. 1

Primary Etiologies to Exclude

Viral Reactivation Syndromes

• Herpes zoster (Ramsay Hunt syndrome) must be excluded in all recurrent cases, as it can present with recurrent episodes and requires different management than idiopathic Bell's palsy. 1
• Herpes simplex virus type 1 reactivation within the geniculate ganglion may trigger recurrent inflammation and nerve entrapment in the bony foramen. 2, 3

Systemic Inflammatory Diseases

• Sarcoidosis must be excluded through chest imaging and ACE level testing, as it causes recurrent facial nerve involvement through granulomatous inflammation. 1
• Autoimmune mechanisms, including cell-mediated immunity against peripheral nerve myelin antigens, may represent a mononeuritic variant of Guillain-Barré syndrome. 3

Infectious Causes

• Lyme disease can cause recurrent or bilateral facial palsy and requires serologic testing based on geographic risk factors and exposure history. 1
• Bacterial infections may contribute to some cases, particularly when neutrophil counts are elevated rather than lymphocytes. 4

Metabolic Disorders

• Diabetes mellitus increases susceptibility to recurrent facial palsy through ischemic and neuropathic mechanisms, and recurrent episodes should prompt evaluation of glycemic control with glucose/HbA1c testing. 1

Structural Lesions Requiring Imaging

• Brain tumors, parotid gland tumors, or cancer involving the facial nerve require MRI with and without contrast to exclude structural causes that were not present during the first episode. 1
• MRI is warranted for any recurrent case, as structural lesions may develop between episodes. 1

Rare but Critical Diagnoses

• Bilateral facial palsy is extremely rare in true Bell's palsy and should immediately trigger investigation for Guillain-Barré syndrome, Lyme disease, or sarcoidosis rather than accepting it as idiopathic. 1
• Melkersson-Rosenthal syndrome has been associated with recurrent facial paralysis. 5

Predisposing Factors

• The frequency and heterogeneity of etiology in recurrent facial palsies suggest either a predisposing anatomic factor or underlying immune mechanisms. 5
• Pregnancy, particularly the third trimester, increases risk of recurrent episodes. 6, 5
• Compromised immune systems may allow viral reactivation or autoimmune reactions against peripheral nerve myelin components. 6, 3

Prognosis Considerations

• Recurrent homolateral facial palsy shows greater reduction in compound action potential compared to single episodes, indicating greater denervation and poorer prognosis. 5
• The temporal bone canal's narrow anatomy means that any recurrent inflammation and edema causes compression with potential for permanent nerve damage, making early intervention critical. 1
• Approximately 30% of patients experience permanent facial weakness even after initial episodes, with recurrent cases carrying higher risk. 1

Mandatory Workup Algorithm

• Laboratory testing: glucose/HbA1c for diabetes screening, Lyme serology if geographically appropriate, ACE levels if sarcoidosis suspected. 1
• Imaging: MRI with and without contrast to exclude structural lesions. 1
• Additional testing: chest imaging for sarcoidosis evaluation, lumbar puncture when Guillain-Barré syndrome is suspected. 1