Facial nerve palsy is a most common disease that affects the cranial nerves whose main symptoms include the muscles of the face being suddenly paralyzed and the forehead, eyes, and mouth being distorted to one side [1]. In Korean medicine, it is mostly expressed as “Guanwasa” [2].

It can be classified as central facial nerve palsy caused by diseases, such as cerebrovascular diseases and brain tumors, and peripheral facial nerve palsy. Peripheral facial nerve palsy can be further classified as Bell’s palsy, primary facial nerve palsy, and secondary facial nerve palsy caused by an etiology, such as infection or trauma. Approximately 70% of patients with facial nerve palsy are categorized as Bell’s palsy, where a specific etiology cannot be identified, followed by patients with facial nerve palsy due to Ramsay Hunt syndrome caused by Herpes zoster virus. Furthermore, approximately 70% of patients with facial nerve palsy can recover naturally within 6 months without treatment, but their prognosis may be poor if underlying diseases are present, such as hypertension and diabetes, or if accompanied by certain symptoms, such as decreased taste [3]. In addition to the symptoms of distortion of the muscles of the face to one side, symptoms, such as pain in the back of the ear, hearing problems, and tear secretion abnormalities, may be present.

Steroid and antiviral drugs [4], manual therapy of the face, and electrical stimulation therapy are initially used [5], whereas herbal medicine, acupuncture, pharmacopuncture, electric needle, thread-embedding therapy, and Chuna treatment are used in Korean medicine [6,7]. The most commonly used tools for the visual assessment of facial nerve palsy include the House–Brackmann grading systems (HBGS) and Yanagihara unweighted grading system (Y-score), which are used to perform static or kinetic assessments according to the examiner’s instructions, and the Sunnybrook facial grading system for the evaluation of aftereffects. Surface electromyography (SEMG), digital infrared thermography imaging (DITI), and electrophysiological tests, such as nerve conductive study and electromyography (EMG), are used [8]. However, such electrophysiological assessment tests are invasive and can cause pain to the patient because the electrode is inserted into the subcutaneous area and only information related to the end of the electrode is detected. In contrast, SEMG is a noninvasive method of attaching electrodes to the surface of the face, which does not cause pain to the patient and can detect all information of a single exercise unit in the muscle [9]. Moreover, it is significant that it can be used in clinical practice in conjunction with the theory of the Meridian muscle in Korean medicine [10]. Recently, studies on the assessment of facial nerve palsy using SEMG have also been reported [11].

Many studies have reported that patients treated with Korean medicine treatments for facial nerve palsy showed favorable treatment outcomes. Moreover, more studies have investigated the efficacy of SEMG, but research on its quantitative measurement and evaluation is insufficient due to the different clinical assessment scales used by Korean medicine doctors. Accordingly, the authors determined the value and usability of various assessment scales in patients with Bell’s palsy by analyzing the correlation between various assessment scales, self-assessment scales, and SEMG.

1. Participants

This study included Bell’s palsy patients who visited the Department of the Facial Nerve Palsy Center at University’s Oriental Medicine Hospital from October 12, 2022, to December 22, 2022. They were briefed on the contents of this study and included inpatients and outpatients who voluntarily agreed to participate. The study subjects could participate in this study for up to 5 Visits at intervals of 2 weeks. On the first visit, 35 people who met the inclusion criteria were assessed, and in this study, 32 cases at Visit 1, 11 cases at Visit 2, and 9 cases at Visit 3 were analyzed, except for those who wanted to stop participating in the study or who could not visit the hospital within the examination period due to personal reasons. This study was conducted in accordance with the approval of the Institutional Review Board (no. DH-2021-06) of the Korean Medical Hospital, Dong-Eui University.

1) Inclusion criteria

The inclusion criteria were as follows: patients aged 19–80 years who had suffered from peripheral facial nerve palsy in the present or past and were complaining of symptoms (above House–Brackmann Grade 2) and who fully understood and could communicate about the progress of the study and voluntarily agreed to participate in this study.

2) Exclusion criteria

The exclusion criteria were as follows: patients who currently have no symptoms of facial nerve palsy (House– Brackmann Grade 1), have a facial nerve palsy due to a central etiology, have difficulty communicating smoothly for the progress of study, or are deemed inappropriate to participate in the study by the primary investigator for other reasons.

2. Methods

For the eligible participants, the examiner performed clinical assessments using the HBGS, Y-score, and SEMG. The symptoms were evaluated subjectively using numerous rating scale (NRS) and facial disability index (FDI), and the accompanying symptoms of facial nerve palsy were assessed. The tests were performed up to 5 times from Visit 1 to Visit 5; the tests on each visit were conducted in the same way and performed at intervals of 2 weeks (15 ± 3 days).

1) Clinical assessment scale

The HBGS is a clinical assessment scale published by House and Brackmann [12] in 1985, and the degree of facial nerve palsy can be classified from normal level 1 without palsy to the most severe level 6. This is currently the most widely used evaluation method for facial nerve palsy [12].

The Y-score is a clinical assessment scale published by Yanagihara in 1976 to evaluate 10 subdivided facial parts from 0 to 4 points according to the degree of facial nerve palsy and finally evaluate the degree of facial nerve palsy. It consists of the following: “asymmetry at rest,” “wrinkle forehead,” “blink,” “closure of the eye lightly,” “closure of the eye tightly,” “wrinkle nose,” “whistle,” “grin,” and “depress lower lip.” Depending on the degree of facial nerve palsy of each category, total paralysis can be scored as zero points, severe paralysis as 1 point, moderate paralysis as 2 points, mild paralysis as 3 points, and normal paralysis as 4 points, with the highest score being 40 [13].

2) Self-assessment scale

The FDI is an evaluation scale created by Van Swearingen and Brach [14] that can evaluate both physical and psychosocial disorders associated with the function of facial nerve muscles. It is based on the SF-36, functional status questionnaire, and Beck depression inventory suitable for facial evaluation and consists of 2 parts: physical function and social/well-being function. It consists of 5 questions each part, from 1 to 5 points per question, and then the total score is calculated by adding the results of [total score − N (number of questions answered)] × 25/N in the physical function part and [total score − N (number of questions answered)] × 20/N in the social/well-being function part [14].

NRS was used as a method of evaluating the degree of discomfort perceived by the patient with a range of 0 to 10; 0 represents a state with no discomfort at all and 10 represents a state with as much discomfort as imaginable. In this study, the normal facial condition before facial nerve palsy was set to 100 points, and the condition with the most severe symptoms of facial nerve palsy was set to 0 points. The patients then scored it subjectively.

The symptoms accompanying facial nerve palsy were divided into parts of the facial region, eyes, ears, mouth, and cervical regions, whereas the other symptoms were investigated using a questionnaire. Four symptoms for the facial region and eyes, 6 symptoms for the ears, 5 symptoms for the mouth and other symptoms, and 1 symptom for the cervical regions were noted.

3) Surface electromyography

SEMG is currently being studied to evaluate the symptoms of facial nerve palsy, and a statistically significant correlation was observed [15]. In this study, SEMG was measured using a QEMG-4 XL (Laxtha), and a single electronic T246H (Bioprotech) was used as the surface electrode. The face was divided into 3 parts (i.e., forehead, cheek, and mouth), and an oriental doctor who was fully aware of the use of the device explained the movement of each part to the patient and evaluated it after practicing the movement. Electrodes were attached to Yangbaek (GB14) on the forehead, the middle point of the ground Jichang (ST4) and Gwallyeo (SI18) on the cheek, and Seungjang (CV24) around the mouth, raising both eyebrows to wrinkle the forehead, pulling the corners of the mouth upward and outward as much as possible, raising the cheeks, and making an “o” shape by rounding both lips. The movements of the frontalis, zygomaticus, and orbicularis muscles were evaluated by repetition after 3 seconds and 5 seconds of rest for each movement (Fig. 1).

Figure 1. Surface electromyography.

Facial nerve palsy was assessed and classified as normal and affected sites. Furthermore, the ratio was obtained by dividing the affected sites and normal sites and multiplying the quotient by 100. The total ratio was obtained by adding the results for the frontalis, zygomaticus, and orbicularis sites and dividing the sum by 3.

Each result of the evaluation was stated as SEMG-F (frontalis), SEMG-Z (zygomaticus), SEMG-O (orbicularis), and SEMG-T (total ratio).

3. Statistical analysis

Statistical processing was performed using SPSS 23.0.11 for Windows (IBM Co.). The Pearson correlation analysis method was used to analyze the correlation between the clinical assessment scale for facial nerve palsy, SEMG, and self-evaluation, and the significance level of all statistical analyses was set at a p-value of < 0.05.

1. Baseline study variables and demographic characteristics of the participants

In this study, 32 participants on Visit 1, 11 on Visit 2, and 9 on Visit 3 were noted. On Visit 1, the participants comprised 16 males (50.0%) and 16 females (50.0%), with an average age of 9.84 years, and the site of facial nerve palsy were 20 cases on the left (59.0%) and 13 cases on the right (41.0%). On Visit 2, the participants comprised f5 males (45.0%) and 6 females (55.0%), with an average age of 52.00 years, and the site of facial nerve palsy were 8 cases on the left (73.0%) and 3 cases on the right (27.0%). On Visit 3, the participants comprised 4 males (44.0%) and 5 females (56.0%), with an average age of 52.11 years, and the site of facial nerve palsy were 7 cases on the left (78.0%) and 2 cases on the right (22.0%). On Visit 1, 14 patients were in the acute phase (44.0%), 16 in the subacute phase (50.0%), and 2 in the chronic phase (6.0%). On Visit 2, 9 patients were in the subacute phase (82.0%) and 2 in the chronic phase (18.0%). On Visit 3, 8 patients were in the subacute phase (89.0%) and 1 patient in the chronic phase (11.0%) (Table 1).

Table 1 . Characteristics of the participants.

	Visit 1 (n = 32)	Visit 2 (n = 11)	Visit 3 (n = 9)
Age	49.84 ± 13.01	52.00 ± 12.35	52.11 ± 11.43
Sex
Male	16 (50.0)	5 (45.0)	4 (44.0)
Female	16 (50.0)	6 (55.0)	5 (56.0)
Site of FP
Left	19 (59.0)	8 (73.0)	7 (78.0)
Right	13 (41.0)	3 (27.0)	2 (22.0)
Morbidity period
Acute	14 (44.0)	0 (0)	0 (0)
Subacute	16 (50.0)	9 (82.0)	8 (89.0)
Chronic	2 (6.0)	2 (18.0)	1 (11.0)

Values are presented as mean ± standard deviation or number (%)..

FP, facial palsy..

2. Average scores of the clinical assessment scales

The average scores of the HBGS were 3.59 (Visit 1), 2.73 (Visit 2), and 2.22 (Visit 3). The average scores of the Y-score were 14.06 (Visit 1), 24.18 (Visit 2), and 30.22 (Visit 3). For the SEMG, the average scores of the frontalis site were 32.77 (Visit 1), 62.62 (Visit 2), and 71.52 (Visit 3). The average scores for the zygomaticus sites were 52.38 (Visit 1), 57.32 (Visit 2), and 70.94 (Visit 3). The average scores of the orbicularis site were 38.23 (Visit 1), 35.34 (Visit 2), and 59.44 (Visit 3). The average scores of the 3 site measurements were 41.13 (Visit 1), 51.76 (Visit 2), and 67.29 (Visit 3).

The average scores of the NRS as evaluated by the patients themselves were 43.06 (Visit 1), 67.27 (Visit 2), and 77.78 (Visit 3). The average scores of the accompanying symptoms were 6.59 (Visit 1), 4.00 (Visit 2), and 3.22 (Visit 3), respectively. Moreover, the FDI scores were 104.63 (Visit 1), 117.00 (Visit 2), and 146.67 (Visit 3) (Table 2).

Table 2 . Average scores of the clinical assessment scales.

	Visit 1 (n = 32)	Visit 2 (n = 11)	Visit 3 (n = 9)
HBGS	3.59 ± 0.62	2.73 ± 0.47	2.22 ± 0.44
Y-score	14.06 ± 7.28	24.18 ± 6.90	30.22 ± 7.05
SEMG-F	32.77 ± 27.02	62.62 ± 35.38	71.52 ± 21.59
SEMG-Z	52.38 ± 41.23	57.32 ± 30.19	70.94 ± 34.20
SEMG-O	38.23 ± 31.98	35.34 ± 28.02	59.44 ± 21.13
SEMG-T	41.13 ± 22.50	51.76 ± 19.19	67.29 ± 11.64
NRS	43.06 ± 25.88	67.27 ± 19.02	77.78 ± 16.98
Accompanying symptoms	6.59 ± 4.00	4.00 ± 3.85	3.22 ± 3.90
FDI	104.63 ± 25.19	117.00 ± 23.57	146.67 ± 34.02

Values are presented as mean ± standard deviation..

HBGS, House–Brackmann grading system; Y-score, Yanagihara unweighted grading system; SEMG_F, surface electromyography frontalis; Z, zygomaticus; O, orbicularis; T, total ratio; NRS, numerous rating scale; FDI, facial disability index..

3. Correlation between the SEMG and assessment scales

On Visit 1, HBGS had a significant negative correlation with all the clinical assessment scales except for the accompanying symptoms. The Y-score had a significant positive correlation with the FDI, while the NRS had a significant positive correlation with the FDI. The FDI has a significant negative correlation with the accompanying symptoms. Among them, the negative correlation between the HBGS and Y-score showed the highest value.

The SEMG-F had a significant negative correlation with the HBGS and a significant positive correlation with the FDI, NRS, Y-score, and SEMT-T. The SEMT-Z had a significant positive correlation with SEMG-T. Moreover, the SEMG-O had a significant positive correlation with the FDI and SEMG-T. The SEMG-T had a significant positive correlation with the NRS and all parts of the SEMG. Among them, the correlation between the SEMG-Z and SEMG-T showed the highest value (Table 3).

Table 3 . Correlation between assessment scales on Visit 1.

Visit 1	HBGS	Y-score	NRS	FDI	Accompanying symptoms	SEMG-F	SEMG-Z	SEMG-O	SEMG-T
HBGS	1
Y-score	−0.787***	1
NRS	−0.499**	0.640***	1
FDI	−0.541**	0.561**	0.530**	1
Accompanying symptoms	0.259	−0.213	−0.296	−0.366*	1
SEMG-F	−0.626***	0.637***	0.603***	0.293	−0.054	1
SEMG-Z	0.049	−0.050	0.121	0.044	0.033	0.197	1
SEMG-O	−0.178	0.115	0.209	0.369*	−0.015	0.187	0.130	1
SEMG-T	−0.305	0.280	0.415*	0.319	−0.009	0.610***	0.752***	0.627***	1

HBGS, House–Brackmann grading system; Y-score, Yanagihara unweighted grading system; NRS, numerous rating scale; FDI, facial disability index; SEMG_F, surface electromyography frontalis; Z, zygomaticus; O, orbicularis; T, total ratio..

*p < 0.05, **p < 0.01, ***p < 0.001..

When the correlation between the SEMG results and detailed parts of the Y-score was analyzed, the SEMG-F had a significant positive correlation with all parts of the Y-score except the Y-4 item (closure of the eye lightly), whereas the SEMG-T had a significant positive correlation with the Y-2 (wrinkle forehead) and Y-9 (grin) items. Among them, the positive correlation between the SEMG-F and Y-2 (wrinkle forehead) showed the highest value (Table 4).

Table 4 . Correlation between Y-Score and SEMG on Visit 1.

Visit 1	Y_1	Y_2	Y_3	Y_4	Y_5	Y_6	Y_7	Y_8	Y_9	Y_10
SEMG-F	0.396*	0.641***	0.513**	0.342	0.494**	0.512**	0.532**	0.451**	0.509**	0.601***
SEMG-Z	−0.044	0.240	−0.029	−0.317	−0.104	−0.143	−0.231	0.022	0.137	0.023
SEMG-O	−0.073	0.143	0.033	−0.109	0.092	0.137	0.168	0.258	0.155	0.169
SEMG-T	0.097	0.472**	0.204	−0.108	0.179	0.183	0.152	0.317	0.361*	0.335

Y-score, Yanagihara unweighted grading system; SEMG_F, surface electromyography frontalis; Z, zygomaticus; O, orbicularis; T, total ratio..

*p < 0.05, **p < 0.01, ***p < 0.001..

On Visit 2, the HBGS had a significant negative correlation with the Y-score, Y-score had a significant positive correlation with the NRS, and FDI had a significant negative correlation with the accompanying symptoms. Among them, the negative correlation between the HBGS and the Y-score showed the highest value.

The SEMG-F had a significant negative correlation with HBGS and a significant positive correlation with SEMG-T. The SEMG-Z showed no significant correlation with the other clinical assessment scales. The SEMG-O had a significant negative correlation with the HBGS and a significant positive correlation with the SEMG-T. Moreover, the SEMG-T had a significant negative correlation with the HBGS and a significant positive correlation with NRS, SEMG-F, and SEMG-O. Among them, the negative correlation between SEMG-O and HBGS showed the highest value (Table 5).

Table 5 . Correlation between assessment scales on Visit 2.

Visit 2	HBGS	Y-score	NRS	FDI	Accompanying symptoms	SEMG-F	SEMG-Z	SEMG-O	SEMG-T
HBGS	1
Y-score	−0.759**	1
NRS	−0.599	0.713*	1
FDI	−0.018	0.231	0.253	1
Accompanying symptoms	0.056	−0.260	−0.383	−0.752**	1
SEMG-F	−0.627*	0.584	0.367	0.003	−0.153	1
SEMG-Z	−0.002	−0.279	−0.442	−0.014	−0.006	−0.326	1
SEMG-O	−0.832**	0.393	−0.442	−0.134	0.109	0.400	0.161	1
SEMG-T	−0.791**	0.114	0.415*	−0.071	−0.044	0.638*	0.402	0.816**	1

HBGS, House–Brackmann grading system; Y-score, Yanagihara unweighted grading system; NRS, numerous rating scale; FDI, facial disability index; SEMG_F, surface electromyography frontalis; Z, zygomaticus; O, orbicularis; T, total ratio..

*p < 0.05, **p < 0.01..

The SEMG-F had a significant positive correlation with the Y-6 (closure the of eye on the involved side only) and Y-7 (wrinkle nose) values, and the SEMG-Z had a significant negative correlation with the Y-1 item (at rest). Among them, the negative correlation between the SEMG-Z and Y-1 (at rest) showed the highest value (Table 6).

Table 6 . Correlation between Y-Score and SEMG on Visit 2.

Visit 2	Y_1	Y_2	Y_3	Y_4	Y_5	Y_6	Y_7	Y_8	Y_9	Y_10
SEMG-F	0.392	0.053	0.264	0.483	0.468	0.723*	0.659*	0.569	0.223	0.417
SEMG-Z	−0.778**	−0.218	−0.096	−0.162	−0.221	−0.209	−0.191	−0.089	−0.236	−0.147
SEMG-O	0.205	0.264	0.289	0.526	0.379	0.527	0.456	0.326	−0.029	0.020
SEMG-T	−0.066	0.047	0.252	0.468	0.356	0.591	0.526	0.461	0.000	0.189

Y-score, Yanagihara unweighted grading system; SEMG_F, surface electromyography frontalis; Z, zygomaticus; O, orbicularis; T, total ratio..

*p < 0.05, **p < 0.01..

On Visit 3, the HBGS had a significant negative correlation with the Y-score and NRS, while the Y-score had a significant negative correlation with the NRS. The FDI had a significant negative correlation only with the accompanying symptoms. Among them, the positive correlation between the Y-score and NRS showed the highest value.

No significant correlation was observed between the clinical assessment scales, except for the positive correlation between the SEMG-Z and SEMG-T (Table 7).

Table 7 . Correlation between assessment scales on Visit 3.

Visit 3	HBGS	Y-score	NRS	FDI	Accompanying symptoms	SEMG-F	SEMG-Z	SEMG-O	SEMG-T
HBGS	1
Y-score	−0.862***	1
NRS	−0.761**	0.903**	1
FDI	−0.503	0.426	0.542	1
Accompanying symptoms	0.259	−0.284	−0.379	−0.743**	1
SEMG-F	−0.423	0.669	0.451	−0.226	0.318	1
SEMG-Z	0.284	0.131	0.153	0.115	−0.500	0.010	1
SEMG-O	0.077	−0.230	−0.105	0.320	0.284	−0.211	−0.476	1
SEMG-T	0.061	0.404	0.365	0.167	−0.122	0.502	0.699*	0.007	1

HBGS, House–Brackmann grading system; Y-score, Yanagihara unweighted grading system; NRS, numerous rating scale; FDI, facial disability index; SEMG_F, surface electromyography frontalis; Z, zygomaticus; O, orbicularis; T, total ratio..

*p < 0.05, **p < 0.01, ***p < 0.001..

The SEMG-F had a significant positive correlation with the Y-6 (closure of the eye on the involved side only) and Y-10 (depress lower lip) items, and the SEMG-F and Y-6 item (closure of the eye on the involved side only) had the highest positive correlation. The SEMG-Z had a significant negative correlation with the accompanying symptoms, except for facial nerve palsy (dizziness, general fatigue and weakness, half-body and general paralysis, including the limbs, memory loss and cognitive impairment, and swallowing disorders) (Table 8).

Table 8 . Correlation between Y-Score and SEMG on Visit 3.

Visit 3	Y_1	Y_2	Y_3	Y_4	Y_5	Y_6	Y_7	Y_8	Y_9	Y_10
SEMG-F	0.304	0.216	0.568	0.638	0.627	0.776*	0.513	0.499	0.557	0.727*
SEMG-Z	−0.081	−0.326	0.146	0.136	0.402	0.152	0.364	−0.255	0.357	0.156
SEMG-O	0.364	−0.194	−0.444	−0.134	−0.500	−0.265	−0.447	0.233	−0.301	−0.174
SEMG-T	0.329	−0.303	0.227	0.448	0.481	0.470	0.404	0.200	0.513	0.498

Y-score, Yanagihara unweighted grading system; SEMG_F, surface electromyography frontalis; Z, zygomaticus; O, orbicularis; T, total ratio..

*p < 0.05..

4. Correlation between the changes in the results of the assessment scales

When analyzing the 9 participants who visited continuously until Visit 3, significant changes were observed in the HBGS, Y-score, NRS, FDI, and accompanying symptoms, while the results of the SEMG, excluding SEMG-Z, also showed significant changes. Accordingly, Pearson correlation analysis was performed to determine the correlation between the changes in Visit 1 and Visit 3 of each clinical assessment scale, and the statistical significance level was set at a p-value of < 0.05.

As a result, the changes in the HBGS had a significant negative correlation with the changes in the results of the NRS, Y-score, and FDI, while the changes in the results of the Y-score had a significant positive correlation with the changes in the results of the NRS and FDI. The changes in the results of the FDI had a significant positive correlation with those of the NRS.

Furthermore, the changes in the results of the SEMG-F had a significant positive correlation with the changes in the results of the NRS and FDI. Changes in the results of the other parts of the SEMG were not significantly correlated with those of the clinical assessment scale, whereas changes in the results of the SEMG-T had a significant positive correlation with the SEMG-Z and SEMG-O (Table 9).

Table 9 . Correlation between the changes in the results of the assessment scales.

	ΔAccompanying symptoms	ΔNRS	ΔHBGS	ΔYT	ΔFDI	ΔSEMG_F	ΔSEMG_Z	ΔSEMG_O	ΔSEMG_T
ΔAccompanying symptoms	1.000
ΔNRS	−0.573	1.000
ΔHBGS	0.587	−0.820**	1.000
ΔYT	−0.391	0.802**	−0.829**	1.000
ΔFDI	−0.587	0.929**	−0.913**	0.731*	1.000
ΔSEMG_F	−0.383	0.795*	−0.557	0.613	0.667*	1.000
ΔSEMG_Z	−0.009	0.611	−0.356	0.185	0.650	0.483	1.000
ΔSEMG_O	0.545	−0.075	0.237	−0.252	−0.067	−0.067	0.367	1.000
ΔSEMG_T	0.187	0.418	−0.119	0.042	0.383	0.467	0.800**	0.667*	1.000

NRS, numerous rating scale; HBGS, House–Brackmann grading system; YT, Yanagihara-total; FDI, facial disability index; SEMG_F, surface electromyography frontalis; Z, zygomaticus; O, orbicularis; T, total ratio..

*p < 0.05, **p < 0.01..

Facial nerve palsy is a disease in which the forehead, eyes, and mouth are distorted to one side due to a sudden paralysis of the facial muscles, which commonly affects the cranial nerves.

It can be divided into central facial nerve palsy caused by brain diseases and peripheral facial nerve palsy, which can be further classified as primary and secondary [16]. Primary facial nerve palsy is often called Bell’s palsy, and approximately 70% of the patients with facial nerve palsy fall into this category. Most patients with facial nerve palsy recover naturally without treatment, but they commonly experience physical discomfort that is caused by the twisting of the muscles of the face, as well as discomfort in social life. Electrophysiological tests and visual assessment systems, such as the HBGS, Y-score, DITI, and SEMG, are used for facial nerve palsy assessment [17].

Currently, various studies are being conducted to determine the effectiveness of SEMG, and the present study was conducted to confirm the effectiveness and objectivity of using the SEMG as a diagnostic tool in patients with facial nerve palsy [18]. The HBGS, Y-score, NRS, FDI, comorbid symptoms, and SEMG were used to evaluate patients who voluntarily decided to participate in this study at the Department of Acupuncture & Moxibustion Medicine, Facial Nerve Palsy Center, Korean Medicine Hospital in University from October 1, 2022, to December 22, 2022. Regardless of the onset date, the participants were selected as patients with symptoms of facial nerve palsy of Grade HBGS 2 or higher, and assessments were conducted for approximately 2 weeks between each visit.

In the correlation analysis between the clinical assessment scales, HBGS had significant negative correlations with other assessment scales, except for the accompanying symptoms on Visit 1, significant negative correlation with the Y-score on Visit 2, and significant negative correlation with the Y-score and NRS on Visit 3. The Y-score had significant positive correlations with the other clinical assessment scales except for the accompanying symptoms on Visit 1, significant positive correlation with the HBGS and NRS on Visit 2, and significant positive correlation with the HBGS and NRS on Visit 3.

In the correlation analysis between the SEMG and clinical assessment scales on Visit 1, SEMG-F had significant correlations with all clinical assessment scales except the FDI and accompanying symptoms, while SEMG-Z showed no significant correlation with other clinical assessment scales. SEMG-O had a significant correlation with the FDI, and SEMG-T had a significant correlation with only the NRS. In the correlation analysis with each detailed part of the Y-score, the SEMG-F had significant correlations with all parts except for “closure of the eye lightly,” and the SEMG-T had significant correlations with the forehead and mouth movements.

In Visit 2, the SEMG-F, SEMG-O, and SEMG-T were significantly correlated with the HBGS, while the SEMG-T was also significantly correlated with the NRS. In the correlation analysis with the Y-score detailed parts, the SEMG-F had a significant correlation with “closure of the eye on the involved side only” and “wrinkle nose,” while SEMG-Z had a significant correlation with the degree of facial asymmetry at rest.

On Visit 3, the SEMG did not have a significant correlation with the clinical assessment scales, but in the correlation analysis with the Y-score detailed parts, the SEMG-F had significant correlations with “closure of the eye on the involved side only” and “depress lower lip.”

When analyzing the patients who were evaluated in the study from Visit 1 to Visit 3, it was found that significant changes were also observed in the SEMG results except for the SEMG-Z along with the HBGS, Y-score, NRS, FDI, and accompanying symptoms. Moreover, a significant correlation was observed between the changes in the SEMG-F and those in the patient self-assessment scales.

In the present study, we confirmed significant correlations between the clinical assessment scales of facial nerve palsy and the results of the SEMG and between the results of the SEMG and the detailed parts of the visual assessment scale. However, as the visit rounds progressed, the number of participants decreased, which is a considered a limitation; therefore, it is necessary to increase the objectivity and effectiveness by securing an adequate number of test participants.

When performing the SEMG test, the participants were guided on the movement of the face, but the patients’ understanding of the movement of the zygomaticus and orbicularis areas was lower than that of the frontalis muscle, and it is thought that the maximum movement was not achieved or a difference was observed between the directions of movement. In the test results, the correlations between the clinical evaluation scales and the SEMG-Z and SEMG-O were not high, which seems to have been influenced by the above variables. Therefore, it is considered necessary to reduce individual differences by having the test operators and study participants familiarize with the SEMG testing methods.

Moreover, unlike previous studies, this study evaluated the study participants using the NRS in which the patients evaluated their condition. It was predicted that the NRS would show a lower score than the actual symptoms because facial nerve palsy causes social discomfort as well as physical discomfort. However, the NRS can also be used as a clinical assessment scale because it shows a significant correlation with the other clinical assessment scales. Moreover, further research is needed on the treatment methods that increase patient satisfaction by analyzing the association with the detailed parts of the Y-score and accompanying symptoms.

From October 12, 2022, to December 22, 2022, clinical evaluation, self-assessment, and SEMG were conducted on the patients with peripheral facial nerve paralysis who visited the Bedding 1st Division of Oriental Medicine Hospital affiliated with Dong-Eui University. The following results were obtained:

1) Significant correlations were observed between the clinical assessment scales at each visit. 2) On Visit 1, significant correlations were observed between the SEMG and clinical assessment scales and between the SEMG-F and some detailed parts of the Y-score. 3) On Visit 2, a significant correlation was observed between the SEMG tests, HBGS, and some detailed items of the Y-score. 4) On Visit 3, some detailed parts of the Y-score were not significantly correlated with the SEMG but significantly correlated with the SEMG-F. 5) A significant correlation was observed between the changes in the results of the clinical assessment scales on Visits 1 and 3 and between the changes in the results of the SEMG-F and those of the patient self-assessment scales.

Conceptualization: HMY, CHK. Data curation: TKK, EJL, CMS. Formal analysis: TKK. Funding acquisition: HMY, YMC. Methodology: HMY, CHK. Project administration: HMY, CHK. Resources: TKK, EJL. Software: JCS, CMS. Supervision: HMY, YMC. Validation: HMY, CHK, TKK. Visualization: TKK, CMS. Writing – original draft: TKK. Writing – review & editing: TKK, EJL, JCS.

The authors have no conflicts of interest to declare.

This study was supported by Grant number KSN 1824130 and KSN1923110 from the Korean Institue of Oriental Medicine.

This study was conducted in accordance with the approval of the Institutional Review Board (no. DH-2021-06) of the Korean Medical Hospital, Dong-Eui University.