Clinical records of children under 19 years of age diagnosed with Bell’s palsy at Pusan National University Hospital between January 2009 and June 2017 were retrospectively reviewed. The criteria for inclusion were a diagnosis of acute peripheral facial nerve palsy, and a follow-up period lasting for at least 1 month. Patients meeting the following criteria were included this study: (1) diagnosed with idiopathic peripheral facial palsy, (2) followed up for at least 1 month, (3) no evidence of systemic diseases, (4) no previous history of facial palsy, and (5) no previous treatment with corticosteroid for facial palsy. Exclusion criteria were (1) facial palsy resulting from other causative conditions, such as congenital diseases, trauma, acute otitis media, and vascular lesions, (2) facial palsy accompanied by palsy of other cranial nerves, (3) previous treatment history, and (4) recurrent facial palsy. Patients with Bell’s palsy were divided into 2 groups: one group received oral steroid treatment (group 1) and the other group did not receive this treatment (group 2). Patients and their parents were fully informed about the course and prognosis of the Bell’s palsy, and steroid treatment was initiated if there was anxiety about prognosis or rejection of conservative treatment.

We conducted a retrospective review of electronic medical records. The following variables were reviewed: onset age, sex, infection and vaccination history, laterality, severity of facial palsy, laboratory findings, magnetic resonance imaging (MRI) findings, treatments, and outcomes. All patients were also examined by an otolaryngologist and an ophthalmologist during the initial work up. The differences in age, sex, laterality, infection or vaccination history, degree of facial nerve palsy, and prognosis after treatment between the groups were analyzed. The House-Brackmann score was used to classify the severity of facial palsy (Table 1). Severity improvement was defined as a decrease in the grade by 2 or more points, or the achievement of grade I. The Institutional Review Board (IRB) of Pusan National University Hospital approved this study (1810-002-071). The requirement for informed patient consent was waived by the IRB.

Statistical analysis was conducted using IBM SPSS Statistics ver. 23.0 (IBM Co., Armonk, NY, USA) and was used to analyze the differences between the groups. Data are presented as means and standard deviations. The Fisher exact test was applied for analyzing categorical data, and the Mann-Whitney test was used for continuous variables. For all analyses, P values <0.05 were considered statistically significant.

A total of 139 patients were diagnosed with facial palsy; however, 23 patients were excluded due to symptoms caused by congenital diseases, trauma, or acute otitis media, or because they had a previous treatment history. Of the remaining 116 patients, 16 patients were excluded due to follow-up loss. Finally, 100 patients were included in our study (Fig. 1). There was no sexual predilection. The mean age at onset was 7.4±5.62 years (±standard deviation), ranging from 2 months to 19 years. Demographic characteristics of the children with Bell’s palsy, and their clinical findings, are shown in Table 2. Right peripheral facial palsies were found in 49 patients (49%).

Thirty-nine patients (39%) had a previous history of infections, such as upper respiratory tract infection, herpangina, and hand-foot-and-mouth disease, within 4 weeks before palsy onset. A respiratory virus polymerase chain reaction (PCR) test were performed in 22 patients (22%) and confirmed that 6 patients were infected with rhinovirus, 1 patient with adenovirus, and 1 patient with coronavirus. The remaining patients did not show a positive result in the respiratory PCR test. Five of the patients under 1 year of age had received vaccinations, such as influenza or DTaP-IPV vaccine within 4 weeks before palsy onset. No fever or other symptoms were observed after vaccination in these patients. Of the patients who underwent blood examinations, 7 patients (22%) tested positive for Epstein-Barr virus immunoglobulin (Ig) M, 3 patients (5%) for Herpes simplex virus IgM, and 4 patients (7%) for varicella zoster virus IgM. In the other patients, no known cause of the facial palsy was found.

Twenty-eight patients (28%) presented with palsy in spring, 21 in summer, 26 in late fall, and 25 in winter. A seasonal variation in the frequency was not observed in our study (Fig. 2).

Blood serologic examinations were conducted in all patients within 7 days of palsy onset. Only 12 patients (12%) showed mild leukocytosis (maximum 14,010 cells/μL). Abnormal findings, such as elevated levels of C-reactive protein or erythrocyte sedimentation rate, were not observed. Of the 60 patients (60%) that underwent cerebrospinal fluid examination, only 2 patients (3.3%) showed pleocytosis. Only one of them showed clinical sign of meningitis, such as headache, and received mannitol treatment (1 g/kg/day) under the diagnosis of viral meningitis.

The severity of facial palsy was classified using the House-Brackmann grade. The numbers of patients with each grade are as follows: grade II, 19 patients (19%); grade III, 45 patients (45%); grade IV, 33 patients (33%); grade V, only 3 patients (3%). There was no significant difference in the severity at onset between the groups (Table 3).

Sixty-three patients (63%) were treated with corticosteroid alone. Ten patients (10%) received an acyclovir (10 mg/kg, every 8 hours) treatment along with steroid. Twenty-seven patients (27%) received only supportive treatments with artificial tears. Oral prednisolone (1 mg/kg/day up to 60 mg/day) was administered to the treated group (group 1) for 7 days, and was gradually tapered for the following 7 days. No adverse effects due to steroid treatment were reported.

There was no significant difference in the mean onset age, the duration from symptom onset to diagnosis, severity, and the duration of follow-up between groups 1 and 2. The outcomes in groups 1 and 2 patients are presented in Table 3. The improvement in the severity grade and the rate of good outcomes did not significantly differ between groups 1 and 2.

In Korea, many people perceive facial palsy as a type of stroke, as a “Wasapung” or “Guanwasa (口眼喎斜) traditionally and are very nervous about it. The caregivers wanted to confirm the absence of any abnormalities. Therefore, we have given enough explanation and then proceeded with the MRI after obtaining consent. Brain MRI was performed in 91 patients (91%) with Bell’s palsy. Twenty-nine patients (31%) with Bell’s palsy showed abnormal MRI findings, that is, thickening and/or enhancement of the facial nerve (Table 2). Eleven patients (12%) were found to have MRI abnormalities that were not associated with Bell’s palsy, such as maxillary or ethmoid sinusitis.

The number of patients between the ages of 1 and 3 years was 39, accounting for 39% of the total cohort (Fig. 3). We classified the patients into 2 groups based on their average age: patients under 8 years of age (55 patients) and patients older than 8 years of age (46 patients). There was no significant difference in sex, site of palsy, severity, and duration of follow-up between these 2 groups. However, the duration from the onset of symptoms to diagnosis was 2.9 days in patients under 8 years and 2 days in patients older than 8 years (P=0.03) (Table 4). This suggests that children who were 8 years of age or older complained of symptoms themselves; therefore, the duration between symptom onset and hospital visit was shorter. Severity improvement was 2.1 in the patients under 8 years and 2.0 in those who were 8 years of age or older. Good outcomes were observed in 52 of 54 patients (96.3%) under 8 years. There was no significant difference between the 2 groups (P=0.27).

The average interval from the first symptom to the hospital visit was 2.5 days in group 1 and 2.6 days in group 2 (P=0.69). There was no significant difference in age and severity between the groups at the time of diagnosis. In group 1, 78 patients (93.2%) had a good outcome, 4 patients (5.5%) remained with grade II or III, and 1 patient (1%) maintained the grade V status. In group 2, 26 patients (96.3%) had normal facial nerve function, and only 1 patient remained with grade III. Thus, a total of 94 patients (94%) showed complete recovery with or without steroid treatment.