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Open Access Highly Accessed Research article

Correlates of degree of nerve involvement in early Bell's palsy

Ru-Lan Hsieh12, Chia-Wei Wu1, Ling-Yi Wang3 and Wen-Chung Lee3*

Author Affiliations

1 Department of Physical Medicine and Rehabilitation, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan

2 Taipei Medical University, Taipei, Taiwan

3 Graduate Institute of Epidemiology, College of Public Health, National Taiwan University, Taipei, Taiwan

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BMC Neurology 2009, 9:22  doi:10.1186/1471-2377-9-22

Published: 7 June 2009



This study aimed to evaluate the still unknown factors correlating with the degree of nerve involvement in early Bell's palsy.


This retrospective chart review study of newly diagnosed cases of Bell's palsy was conducted over a three-year period. Information on age, sex, day of onset, comorbidities, corticosteroid use, and electroneurographic test results were collected. The electroneurographic quotient (amplitude of compound muscle action potential on the affected side divided by that on the healthy side and expressed in percent) was used as an index of nerve involvement, with lower quotient indicating more severe disease.


Data were collected on 563 patients. The mean electroneurographic quotient varied inversely with age (p < 0.001) and was higher in patients who used corticosteroids than those who did not (47.1% vs. 40.3%; p = 0.002). There was no correlation between the degree of nerve involvement and sex, season of onset, hypertension, or diabetes.


The degree of nerve involvement in early Bell's palsy correlates positively with age and negatively with corticosteroid use.