Introduction
Bell’s palsy (BP) is a condition/disease in which facial muscle movement is impaired due to facial nerve palsy and is one of the most common causes of facial nerve disorders. Its incidence is reported to be 11–40 cases per 100,000 people [
1]. In general, BP is accompanied by unilateral acute facial paralysis, which gradually worsens over 24–48 hours, and facial weakness worsens up to 3–7 days [
2,
3]. It is reported that the incidence of BP is high between the ages of 15 to 50 years, and there is no difference in the incidence between the sexes [
4]. It has been reported that about 80% of patients recover within 4–8 weeks without treatment, but if recovery is delayed beyond 3 months after the onset, incomplete recovery, synkinesis due to incorrect nerve re-regulation, and crocodile tears may occur [
5]. Prognostic factors that affect patient recovery from BP include sex, age, presence of hypertension and diabetes, a history of smoking, nerve conduction test results, severity of the initial paralysis, and degree of recovery from the initial paralysis [
6–
9].
BP treatment includes drug therapy, physical therapy, and surgical therapy. The most commonly used drugs are steroids and antivirals, which reduce inflammation and swelling at the injured site [
10]. Acupuncture and herbal medicine are the most common Korean medicine treatments for BP, and other methods such as electroacupuncture, pharmacopuncture, thread-embedding therapy, and chuna therapy are also used [
11–
15]. Although there have been many case reports and studies on Korean medicine treatment for BP [
16,
17], there are no reports on the correlation between patients’ with BP and their visits to a Korean medicine institution and the factors that affect their condition.
Therefore, the effects of hospitalization, steroid use, treatment frequency, and duration of BP among patients who were treated at a Korean Medicine hospital from August 01, 2018 to July 31, 2021 were analyzed. Retrospective analysis of these factors and their correlations are reported in this study.
Discussion
BP is the most common cause of facial nerve palsy, accounting for approximately 51% of all patients with facial nerve palsy. It can occur at any age, but its incidence is relatively low in children under 10 years and in the elderly [
18]. It has been reported that the probability of developing BP is high during pregnancy [
19], and in the presence of underlying conditions/diseases such as hypertension or diabetes [
20,
21]. Reactivation of latent herpes virus is the main cause of facial nerve edema [
22]. Most facial nerve palsies caused by viral damage recover spontaneously, but only about 71% recover completely if not properly treated [
23]. One study reported that steroid administration at the early stage of onset prevents nerve edema progression and nerve damage, thereby reducing the risk of permanent facial nerve paralysis [
24].
Recently, in many Korean Medicine hospitals and clinics, many Korean-Western cooperative treatments have been implemented [
25–
27]. However, no study has analyzed the correlation between hospital visits among patients with BP and treatment tendencies.
Of the included patients, 283 patients (34.7%) visited the hospital between August 01, 2018, and July 31, 2019, 274 patients (33.6%) visited the hospital from August 01, 2019 to July 31, 2020, and 259 (31.7%) patients visited the hospital from August 01, 2020 to July 31, 2021. Notably, the number of patients who visited the hospital for BP decreased every year. This is similar to the report of the 2018–2020 Health Insurance Statistical Yearbook published by the Health Insurance Review and Assessment Service and the National Health Insurance Corporation [
28–
30].
Demographic statistics of the patients showed that 392 (48.0%) were men and 424 were women (52.0%) showing a similar incidence rate between men and women. The average age was 52.28 years, those in their 50s accounted for most of the population (
n = 209, 25.6%), with those in their 60s accounting for 181 people (22.2%), those in their 40s accounting for 147 people (18.0%), and those in their 40s and 60s accounting for 75.8% of the total. This observation was consistent with the results of previous studies that showed that the majority of patients treated for BP were in their 40s and 60s [
31].
As a result of investigating condition/disease characteristics, the most common occurrence was in March, with 89 patients (10.9%), followed by 78 patients (9.6%) in September and 76 patients (9.3%) in January. The month with the least number of patients was May, with 53 patients (6.5%) visiting the hospital. Prior studies that investigated the correlation between the incidence and season of BP cases were reviewed and it was concluded that results were inconsistent [
32]. In this current study no statistical significance between incidence and season was identified. The left side was affected in 399 patients (48.9%) with BP and the right side was affected in 416 patients (51.0%) suggesting a relatively even distribution similar to the results of a previous study [
33]. Analysis of the underlying conditions/diseases revealed that 185 (22.7%) patients had hypertension and 127 (15.6%) had diabetes. Notably, hypertension and diabetes are the most common conditions of vascular disease and are considered to be risk factors for BP [
20,
21]. Analysis of relapse revealed that 99 patients (12.1%) visited the hospital with recurrent BP, which is in agreement with the incidence of recurrent BP (range from 0.8–19.4%) in a previous study [
34].
Analysis of the therapeutic characteristics revealed that 417 patients (51.0%) received outpatient treatment only, and the remaining 399 patients (49.0%) received inpatient treatment. About half of the patients who came to the hospital with BP chose to be admitted. The number of outpatient treatments was 165 (39.6%) with 1–5 treatments, 68 (16.3%) with 6–10 treatments, and 52 (12.5%) with 11–15 treatments. As the rounds progressed, the number of patients who continued treatment decreased. As a result of analyzing the length of hospitalization, 159 patients (39.8%) were hospitalized for 1–2 weeks, 99 patients (24.8%) for 2–3 weeks, and 82 patients (20.6%) for less than 1 week. When the total treatment period was investigated for all patients, the mean and standard deviation were 63.21 ± 114.40 days. Notably, 455 patients (55.8%) were treated for less than 1 month, and 151 patients (18.5%) received treatment from 1 month to less than 2 months. Therefore, patients who were treated for less than 2 months accounted for 74.3% of the total study population. This finding was consistent with the results of a previous study which reported that 70–80% of patients with BP fully recovered within 2 months [
18]. However, a follow-up study is needed to determine the number of treatments that ended due to recovery from the condition/disease.
As a result of analyzing the correlation between sex and the use of steroids, it was determined that among men, 355 patients (90.6%) received steroid treatment, which was relatively higher than in women, 359 (84.7%). It has previously been reported that female patients are more satisfied with Korean medicine treatment than male patients [
35]. However, it remains unclear whether sex preferences for Korean medicine treatment affected this result. Furthermore, restrictions on steroid combination treatment due to age or underlying conditions/diseases, such as diabetes, may impact these findings.
The use of steroids in each time period of a year was examined, and compared against 2018.08–2019.07, when the Korean medicine alone treatment group accounted for 18.7% of the total, in 2019.08–2020.07 and 2020.08–2021.07, this patient cohort decreased by approximately half, to 8.4% and 10.0%, respectively. In other words, more recently, patients with BP tended to choose steroid combination therapy rather than Korean medicine alone. It is possible that the use of steroid combination therapy has increased for reasons such as active recommendations from medical staff on steroid combination therapy or increased awareness of patient conditions/diseases.
Analysis of the use of steroids for inpatients revealed that 377 patients (94.3%) were in the steroid combination group, which was higher than the 338 patients (81.1%) in the outpatient steroid combination group. The reason for this may be that it is easy for inpatients to receive steroid combination treatment at Korean-Western cooperative hospitals through Korean-Western collaborations.
Analyzing whether steroid combination therapy was used according to recurrence, it was determined that 635 patients (88.6%) among the initial onset cohort received steroid combination therapy, while 79 patients (79.8%) received steroid combination therapy among the relapse cohort. In the case of an initial occurrence, unless the patient was old or had underlying conditions/diseases, there was a high possibility of receiving the steroid combination treatment according to the recommendation of medical staff. However, in case of relapse, it seems that Korean medicine treatment was preferred rather than conventional Western treatment.
As a result of analyzing the inpatient treatment rate according to sex, 224 (52.8%) women received inpatient treatment, which was higher than men (n = 176, 44.9%). This is thought to be the result of conditions such as social factors including social activity and occupation.
Analysis of the inpatient treatment rate according to age showed that among teenage patients, 14 (77.8%) were hospitalized, which was the highest recorded rate. Furthermore, 14 patients (56.0%) in their 80s or older, 114 patients in their 50s (54.5%), 92 patients in their 60s (50.8%), and 37 patients (46.8%) in their 70s required hospitalization. People in their 20s–40s are relatively socially active, so this is thought to result in the lower hospitalization rate than teenagers, and those in their 80s.
Among the patients with hypertension, 124 (67.0%) were hospitalized, and among patients with diabetes, 82 (64.6%) were hospitalized. The hospitalization rate of these patients was comparatively high. Although previous studies have reported that hypertension and diabetes do not correlate with the degree of recovery from BP [
36], it was hypothesized that the presence of an underlying condition/disease may factor into the patients’ preferences for inpatient treatment. Furthermore, as the hospitalization rate increased in patients over 50, the association between age and underlying condition/disease may also have been a factor.
As a result of analyzing the differences in the total treatment period by 1 year time periods using 1-way ANOVA, the total treatment period decreased from 2018 to 2021. This is because the individuals in this study were patients at a Korean Medicine hospital. Furthermore, the patients likely chose outpatient treatment at a nearby Korean clinic after treatment at a hospital-level medical institution and the steroid combination treatment likely affected the treatment period. For a more accurate prediction, a follow-up study on the recovery rate from the condition/disease and the duration of treatment is needed.
Analysis of the difference in the number of outpatient treatments for hypertension using the independent sample
t test showed that the average number of treatments for patients with hypertension was 22.59 days, which was higher than the 14.82 days for patients without hypertension. In a previous study on the prognostic factors of BP and Ramsay Hunt syndrome, patients without hypertension showed a higher degree of improvement in Ramsay Hunt syndrome than patients with hypertension (
p = 0.025). However, the relationship between the degree of severity and recovery has not yet been elucidated [
37]. Therefore, a follow-up study is needed to determine whether hypertension affects the degree of improvement in BP and increases the number of treatments required.
Multiple linear regression analysis was performed to analyze the variables that influenced the total treatment period. Notably, the total treatment period in the steroid combination group was less than the non-steroid group for all patients. Analysis of each group of outpatients and inpatients also confirmed that the number of outpatient treatments and the length of hospitalization was less in the steroid combination treatment group. This is in agreement with the results of previous studies, in which the patient group that received Korean-Western combination treatment showed a significantly higher degree of improvement than the patient group that received Korean medicine treatment alone [
25–
26]. In addition, the total treatment period shortened over each onset time period. This finding was also consistent with the observation that the mean total treatment period gradually decreased each year in the previous 1-way ANOVA evaluation. The fact that the number of outpatient treatments decreased in the group without hypertension compared with the hypertension group is also consistent with the previous analysis in this study where the independent sample
t test was used. In addition, the length of hospitalization was greater for women compared with men, consistent with the above-described difference in hospitalization rates by sex.
Binary logistic regression analysis of the variables that affected hospitalization showed that when the patient was female, the onset time period was earlier, steroid treatment was used, and there were underlying conditions/diseases such as hypertension and diabetes, and the odds ratio for inpatient treatment was higher than for those who only received outpatient treatment. Sex, steroid use, and underlying conditions/diseases had the same results as determined in the previous crossover analysis. Although the cross-analysis revealed that the differences in hospitalization rate by 1 year period was not statistically significant, the number and proportion of patients tended to decrease with each passing year: 174 patients (51.9%) in 2018.08–2019.07, 132 (48.2%) in 2019.08–2019.07, and 121 (46.7%) in 2020.08–2021.07. The 2018–2020 Health Insurance Statistical Yearbook, reported the number of patients hospitalized for facial neuropathy at Korean Medicine institutions gradually decreased from 2018 to 2020, in agreement with the results of this study. However, the number of hospitalized patients with facial neuropathy has been reported to have gradually increased in all medical institutions from 2018 to 2020, which conflicts with our results [
28–
30]. It is possible that increased awareness of conditions/diseases may lead patients to choose steroid therapy in Western medicine institutions rather than Korean Medicine institutions. Publicity is needed to raise awareness of Korean medicine treatment.
Analysis of the variables that influence the use of steroids revealed that the odds ratio of not receiving steroid combination treatment was higher in women than in men, in older age cohorts, in earlier onset, during relapse rather than initial onset, and in outpatient treatment rather than hospitalization. The factors related to sex, onset time period, recurrence, and hospitalization that were identified in this study agreed with previous cross-analysis results. In relation to the decrease in the rate of receiving steroid combination therapy with age, steroid combination treatments were examined according to age. Even though the results of the cross-analysis were not statistically significant (
p = 0.083), from the teen to the 60s cohorts, the rate of the steroid combination treatment ranged from a high of 80% to a low of 90%, and after the 70s, the rate of steroid combination treatment decreased sharply. This is presumably because elderly patients are burdened with active steroid combination treatment due to underlying conditions/diseases, such as diabetes. In addition, steroid preparations have the potential to induce hypertension due to sodium retention, vasoconstriction, and norepinephrine action-enhancing effects [
38], which leads to a lower rate of steroid administration in the elderly than in other age groups.
This study is significant in that it evaluated patients who received Korean medicine treatment, unlike previous studies that investigated the clinical features of patients with BP who visited Korean Medicine institutions [
31,
39]. Furthermore, this study included a large number of patients compared with previous studies and evaluated treatment periods, frequency, and total treatment period according to the classifications of inpatients and outpatients, which were not performed in previous studies.
However, this study has a limitation in that it is difficult to obtain accurate information by estimating the degree of improvement throughout the treatment period. Due to the large number, the evaluation of each patient's condition/disease state was not made, such as the use of the House-Brackmann grade or Yanagihara score. This was also a retrospective study based on data collected through medical records, which may be subject to bias. We hope that further studies will address these limitations in the future.