Introduction
Bell palsy (BP) is an acquired, idiopathic facial palsy linked to lower motor neuron
malfunction of the seventh cranial nerve. It typically affects one side of the face
and is characterized by weakening or palsy of the facial muscles.[1]
When no other reason can be found, BP is diagnosed through exclusion criteria, and
inflammatory, traumatic, and viral processes are the most frequently acknowledged
causes. The condition is associated with viral infection,[2] usually by members of the Herpesviridae family.
Facial nerve palsy (FNP) is a condition that frequently manifests in emergency rooms
in pediatric patients who have suffered accidents. Because of its abrupt onset and
frequently rapid progression, it needs to be diagnosed as soon as possible to minimize
the effects on patient morbidity and quality of life.[3]
A frequent issue, FNP significantly lowers the quality of life of patients. The incidence
rates among children are of 2.7 per 100 thousand individuals per year for those under
the age of 10, and of 10.1 per 100 thousand individuals per year for those between
the ages of 10 and 20. Yet, the prevalence rate varies from 10 to 30 per 100 thousand
individuals. In the pediatric emergency room, FNP is a concerning symptom that demands
an immediate diagnosis.[4]
In children, BP has a favorable prognosis, with studies[5] indicating that 80 to 90% of children recover fully within 6 months of symptom onset.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been identified as
a highly-morbid and potentially-fatal virus that causes coronavirus disease 2019 (COVID-19),
which developed into a pandemic. It was isolated from human airway epithelial cells
and belongs to the coronavirus family. With an average incubation period of 5 to 7
days, this virus spreads by droplets and direct contact.[6]
[7]
It is known that coronaviruses have a propensity for neuroinvasiveness,[8] and COVID-19 patients may exhibit neurological symptoms. When COVID-19 initially
manifests, neurological symptoms, such as headaches, hyposmia, hypogeusia, dizziness,
disorientation, cerebrovascular disorders, Guillain-Barré syndrome (GBS), and encephalopathies
may also occur concurrently with respiratory symptoms. Up to 36% of COVID-19 patients
have exhibited neurological symptoms, particularly those with severe respiratory tract
infections.[9]
[10]
One of the several neuropathies that COVID-19 patients have experienced, in many cases
BP was the only significant neurological condition documented.[11] Several studies have identified FNP because of COVID-19, either as an isolated symptom
in otherwise asymptomatic patients or in combination with other COVID-19 symptoms.[12]
The present work aims to study if there is an association between BP and COVID-19
in pediatric patients, as well as the pattern of recovery in pediatric cases of BP
during the COVID-19 pandemic.
Methods
We performed a prospective cohort study on pediatric patients with acute onset unilateral
facial weakness of unknown etiology (BP) during the pandemic period.
The study was conducted at the Department of Otorhinolaryngology and Head and Neck
Surgery, Kafrelsheikh University Hospital, from July 2020 to June 2022 and was approved
by the hospital's Ethics Committee (under code MKSU 50–2-7). Written informed consent
was obtained from the parents of the included patients.
All patients in the study presented to our clinic with a complaint of acute facial
paralysis; as part of the routine process to investigate the etiology of the facial
paralysis, they were submitted to a detailed anamnesis, an ear, nose, and throat examination,
a complete neurological examination, complete blood count, biochemical blood tests,
and viral serologies (particularly herpes simplex virus [HSV], human immunodeficiency
virus [HIV], and varicella-zoster virus [VZV]); a history of trauma warrants investigation
for other stigmata of temporal bone fractures during the physical examination and
cranial and temporal MRI scans were also performed. We excluded adult patients (older
than 18 years) and those submitted to immunization with a live vaccine or COVID-19
vaccine within the previous month.
After ruling out the known causes, patients with idiopathic lower motor neuron facial
paralysis (BP) were included in the present study. Furthermore, for all included patients,
we performed a reverse transcription-polymerase chain reaction (RT-PCR) test through
nasopharyngeal and oropharyngeal swabs for SARS-CoV-2 at the time of the BP diagnosis.
The severity of the FNP was assessed and graded using the House-Brackmann (H-B) score.[13]
All patients underwent the same treatment protocol (except if there was a contraindication
to corticosteroids), which included prednisone 1 mg/kg/day, which was tapered and
stopped in 2 weeks, in addition to meticulous eye care. All patients were followed
up at 1 week, 2 weeks, 1 month, 3 months, and 6 months to check for resolution of
the facial weakness.
The sample was divided into three groups according to the degree of recovery by comparing
the severity of BP between the time of diagnosis and the patient's follow-up visit:
complete recovery, partial recovery, and non-recovery. The complete recovery group
was defined as H-B grade 1, the partial recovery group was defined as those who had
experienced an improvement of at least 1 H-B grade, but not an improvement to grade
1, and the non-recovery group was composed of the subjects whose severity score had
not changed or was worse than when they had been diagnosed.
The participants who had fully recovered at the 1-month follow-up visit were not required
to return to the study site for the remaining time points of the study; instead, their
parents/guardians were asked by phone about the child's condition and, in case of
the appearance of new manifestations, they were asked to visit our clinic. Similarly,
participants with full recovery at the 3-month follow-up visit were not required to
return to the study site for the follow-up at 6 months.
We also calculated the incidence rate of pediatric cases of BP in the past 5 years
in the Kafr El Sheikh Governorate, where the study was conducted. The number of new
BP cases admitted to our hospital in that period was divided by the pediatric population
(individuals younger than 18 years) of the area to calculate the yearly incidence
rates, which were compared with those of other years.
Statistical Analysis
The data was analyzed using the IBM SPSS Statistics for Windows (IBM Corp., Armonk,
NY, United States) software, version 26.0. The quantitative variables were expressed
as mean and standard deviation values, and the categorical variables, as absolute
frequencies; the Chi-squared trend test was used to compare them (in the case of ordinal
data). To validate the assumptions for use in parametric tests, the Kolmogorov-Smirnov
(distribution-type) and Levene (homogeneity of variances) tests were used. The Wilcoxon
signed-rank test was used to compare one group in terms of an ordinal variable throughout
two time points. To investigate differences in variable distribution within one group,
the one-sample Chi-squared test was used. The level of statistical significance was
set at p < 0.05. A highly significant difference was present if p ≤ 0.001.
Results
The present study included 27 patients with facial palsy, 15 (55.6%) of whom were
female subjects. The age ranged from 2 to 16 (mean: 9.04 ± 3.14) years. In total,
14 patients presented a left-side lesion. There were only 2 (7.4%) cases of confirmed
COVID-19 infection, with a statistically significant difference in terms of distribution
([Table 1]).
Table 1
Distribution of patients (N = 27) according to demographic data
|
n
|
%
|
|
Gender
|
|
|
|
Female
|
15
|
55.60%
|
|
Male
|
12
|
44.40%
|
|
Age (years):
|
|
|
|
Mean ± standard deviation
|
9.04 ± 3.14
|
|
Range
|
−16
|
|
Side of the lesion
|
|
|
|
Left
|
14
|
51.90%
|
|
Right
|
13
|
48.10%
|
|
SARS-COV-2 RT PCR:
|
|
|
|
Negative
|
25
|
92.60%
|
|
Positive
|
2
|
7.40%
|
|
p
|
< 0.001**
|
|
Abbreviations: RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute
respiratory syndrome coronavirus 2.
Notes: **One-sample Chi-squared test; statistically, p ≤ 0.001 is highly significant in the assessment of the grade of facial nerve affection
in coronavirus disease 2019 (COVID-19) patients; the only 2 patients with confirmed
COVID-19 in the present study were grade IV on the House-Brackman facial nerve grading
system.
After 1 month, 15 patients (55.6%) were H-B grade I, and there were no cases of grade
V with significant improvement (p < 0.001). After 3 months, 20 patients (74.1%) were H-B grade I, with significant
improvement at 3 months when compared with the evaluation after one month. The rate
of grade-I patients rose to 81.5% after 6 months, without significant changes when
compared with the assessment after 3 months ([Table 2]).
Table 2
Change in House-Brackman grade throughout 6 months among the studied patients (N=
27)
|
House-Brackmann grade
|
Initial: n
(%)
|
After 1 month: n
(%)
|
After 3 months: n
(%)
|
After 6 months: n
(%)
|
|
I
II
III
IV
V
|
0 (0%)
3 (11.1%)
8 (29.6%)
13 (48.1%)
3 (11.1%)
|
15 (55.6%)
6 (22.2%)
2 (7.4%)
7 (14.8%)
0 (0%)
|
20 (74.1%)
2 (7.4%)
3 (11.1%)
2 (7.4%)
0 (0%)
|
22 (81.5%)
1 (3.7%)
2 (7.4%)
2 (7.4%)
0 (0%)
|
|
p
|
|
< 0.001**
|
0.011*
|
0.083
|
Notes: the p-values pertain to the Wilcoxon signed-rank test; *statistically significant; ** highly
significant.
After 1 month, 15 patients (55.6%) presented complete improvement, while 3 patients
(11.1%) presented no improvement. In the third month, 20 patients (74.1%) were grade
I, with significant improvement when compared with the evaluation after 1 month. After
6 months, no significant changes were observed compared with assessment after 3 months,
in which 22 patients (81.5%) showed complete improvement ([Table 3]).
Table 3
Recovery of the facial nerve throughout 6 months among the studied patients (N = 27)
|
Recovery
|
After 1 month: n
(%)
|
After 3 months: n (%)
|
After 6 months: n (%)
|
|
Complete
Partial
None
|
15 (55.6%)
9 (33.3%)
3 (11.1%)
|
20 (74.1%)
5 (18.5%)
2 (7.4%)
|
22 (81.5%)
3 (11.1%)
2 (7.4%)
|
|
p
|
|
0.014*
|
0.157
|
Notes: the p-values pertain to the Wilcoxon signed-rank test; *statistically significant.
No significant differences were found regarding gender and recovery in the first,
third, or sixth months. By the end, 2 female patients (7.4%) presented no improvement,
and all male patients presented some degree of improvement. Complete improvement was
observed in 11 (73.3%) of the female patients and in 11 (91.7%) of the male patients
([Table 4]).
Table 4
Relationship between gender and recovery from facial nerve affection
|
Recovery
|
Female patients (N = 15)
|
Male patients (N = 12)
|
χ2
|
p
|
|
n (%)
|
n (%)
|
|
After 1 month
|
|
|
0.855
|
0.355
|
|
Complete
|
8 (53.3%)
|
7 (58.3%)
|
|
Partial
|
4 (26.7%)
|
5 (41.7%)
|
|
None
|
3 (20%)
|
0 (0%)
|
|
After 3 months
|
|
|
3.51
|
0.061
|
|
Complete
|
9 (60%)
|
11 (91.7%)
|
|
Partial
|
4 (26.7%)
|
1 (8.3%)
|
|
None
|
2 (13.3%)
|
0 (0%)
|
|
After 6 months:
|
|
|
1.892
|
0.169
|
|
Complete
|
11 (73.3%)
|
11 (91.7%)
|
|
Partial
|
2 (13.3%)
|
1 (8.3%)
|
|
None
|
2 (13.3%)
|
0 (0%)
|
Abbreviation: χ2, Chi-squared trend test.
There was a statistically insignificant relationship between age and recovery in the
first, third, or sixth months. By the end of 6 months, all patients aged < 9 years
presented complete resolution, as well as 12 (70.6%) of those aged ≥ 9 years ([Table 5]).
Table 5
Relationship between age and recovery from facial nerve affection
|
Recovery
|
< 9 years (N = 10)
|
≥ 9 years (N = 17)
|
χ2
|
p
|
|
n (%)
|
n (%)
|
|
After 1 month:
|
|
|
0.064
|
0.8
|
|
Complete
|
5 (50%)
|
10 (58.8%)
|
|
Partial
|
4 (40%)
|
5 (29.4%)
|
|
None
|
1 (10%)
|
2 (11.8%)
|
|
After 3 months
|
|
|
2.248
|
0.134
|
|
Complete
|
9 (90%)
|
11 (64.7%)
|
|
Partial
|
1 (10%)
|
4 (23.5%)
|
|
None
|
0 (0%)
|
2 (11.8%)
|
|
After 6 months:
|
|
|
3.022
|
0.082
|
|
Complete
|
10 (100%)
|
12 (70.6%)
|
|
Partial
|
0 (0%)
|
3 (17.6%)
|
|
None
|
0 (0%)
|
2 (11.8%)
|
Abbreviation: χ2, Chi-squared trend test.
No significant differences were found involving COVID-19 infection and recovery in
the first, third, or sixth months. A total of 2 patients (7.4%) had COVID-19 infection
and experienced complete improvement in the first month, as did 13 (52%) of non-COVID
patients. According to the results, it seems that there is no association between
COVID-19 infection and facial palsy; however, the patients infected with COVID-19
in the sample experienced a rapid, early recovery from BP ([Table 6]).
Table 6
Relationship between COVID-19 infection and recovery from facial nerve affection
|
Recovery
|
Negative patients (N = 25)
|
Positive patients (N = 2)
|
χ2
|
p
|
|
n (%)
|
n (%)
|
|
After 1 month
|
|
|
1.368
|
0.242
|
|
Complete
|
13 (52%)
|
2 (100%)
|
|
Partial
|
9 (36%)
|
0 (0%)
|
|
None
|
3 (12%)
|
0 (0%)
|
|
After 3 months
|
|
|
0.624
|
0.43
|
|
Complete
|
18 (72%)
|
2 (100%)
|
|
Partial
|
5 (20%)
|
0 (0%)
|
|
None
|
2 (8%)
|
0 (0%)
|
|
After 6 months:
|
|
|
0.411
|
0.521
|
|
Complete
|
20 (80%)
|
2 (100%)
|
|
Partial
|
3 (12%)
|
0 (0%)
|
|
None
|
2 (8%)
|
0 (0%)
|
Abbreviation: χ2, Chi-squared trend test; COVID-19, coronavirus disease 2019.
The mean incidence of BP in 5 years (2017–2021) was of 1.73/100 thousand individuals,
with a statistically insignificant change throughout the years ([Table 7]).
Table 7
Incidence rate of facial palsy from 2017 to 2021
|
Year
|
Cases
|
Pediatric population
|
Incidence rate
|
Mean incidence
|
|
2017
|
13
|
866,138
|
1.5 /100,000
|
1.73/100,000;
p = 0.2
|
|
2018
|
16
|
883,929
|
1.81 /100,000
|
|
2019
|
15
|
901,572
|
1.66 /100,000
|
|
2020
|
16
|
919,052
|
1.74 /100,000
|
|
2021
|
18
|
936,330
|
1.92 /100,000
|
Discussion
Although the precise pathophysiology of acute-onset facial nerve paralysis is unknown,
it is believed to be connected to axonal spread and viral replication in conjunction
with neurotropic herpes viruses (HSV and VZV), which cause inflammation and demyelination
in the nerve.[14] In the population of children, BP accounts for 60 to 80% of cases of FNP.[15]
The olfactory nerve and bulb, which are directly connected to the central nervous
system, are two pathways by which SARS-CoV-2 might enter the central nervous system.
The other is through viremia. To date, there are few reports in the literature of
investigations on the neurological side effects of COVID-19, such as the study by
Mao et al.[9]
It is still unclear how SARS-CoV2 manifests in young patients. Pediatric patients
have been observed to have respiratory conditions, leukopenia, thrombocytopenia, myocarditis,
interstitial pneumonia, Kawasaki-like sickness, and vasculitis.[16]
Incidence Rate of Facial Nerve Palsy in Children
In the present study, the mean incidence of BP in children from 2017 to 2021 was of
1.73/100 thousand individuals, with a statistically insignificant change throughout
the years.
The incidence of BP is debatable; however, Yılmaz et al.,[17] in a retrospective investigation of 81 children (aged 1 to 16 years) in Turkey between
2011 and 2013, found that 80.2% of peripheral FNP cases had idiopathic causes. According
to Rowhani-Rahbar et al.,[18] for every 100 thousand children under the age of 18, there are 19 to 21 cases of
BP. Rowlands et al.[19] have stated that FNP is expected to affect 2.7 per 100 thousand children under the
age of 10, and 10.1 per 100 thousand children aged 10 to 20.
According to Mutlu et al.,[20] 98% of patients referred to their clinic with idiopathic lower motor neuron FNP
received negative results from SARS-CoV-2 RT-PCR tests, and there was no rise in the
number of patients with this condition during the COVID-19 outbreak.
The incidence of pediatric FNP in 2020 was not noticeably different from the rate
in the preceding 5 years, according to Barron et al.[21] On the other hand, Zammit et al.[22] found a statistically significant increase in the number of cases of BP in 2020
(3.5%) compared with 2019 (1.3%), and they determined that SARS-CoV-2 may be blamed
for BP in COVID-19 patients. In their 2021 retrospective analysis, Codeluppi et al.[23] noticed a higher prevalence of BP during the COVID-19 pandemic compared with the
same period the previous year; according to them, 21% of BP patients presented active
or recent SARS-CoV-2 infection symptoms, indicating a higher risk of developing BP
during or after COVID-19.
Hogg et al.[24] found a substantial rise in the incidence of pediatric cases of BP during the COVID-19
epidemic compared with the previous year. Moreover, Brisca et al.[25] discovered an extraordinary rise in children with COVID-19-related FNP between March
and April 2020.
According to Srinivas et al.,[26] there were more cases of BP in 2020 (0.8%) than during the prepandemic period (0.05%).
Moreover, Tamaki et al.[27] revealed a higher prevalence of BP in patients with COVID-19 in August 2021.
Distribution of Patients according to Demographic Data
The present study included 27 patients with facial palsy with ages ranging from 2
to 16 (mean: 9.04 ± 3.14) years; only 2 (7.4%) had confirmed COVID-19 infection.
Theophanous et al.[2] reported the first pediatric case of BP associated with COVID-19 infection. They
described a medically difficult case of a 6-year-old male patient with unilateral
FNP and a positive SARS-CoV-2 RT-PCR. There was no history of trauma, illness, or
recent travel.
On the other hand, a retrospective analysis of the prevalence of FNP between 2015
and 2020 was performed by Barron et al.,[21] who found that the incidence of BP in 2020 did not differ from that of the previous
5 years. They could not find a connection between COVID-19 and FNP in children, as
no evidence of COVID-19 infection was detected upon admission.
In a case series conducted in Brazil from May to July 2020, Lima et al.[12] identified 8 patients who had FNP during the pandemic and had positive SARS-CoV-2
RNA after reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in
nasal and nasopharyngeal swabs.
Likewise, Zammit et al.[22] reported a much higher incidence of FNP in 2020 than in 2019 and suggested the COVID-19
pandemic as the cause of the surge. Only 17 (57%) out of their 30 patients underwent
COVID-19 testing, and among those, only 2 had a positive result.
Change in House-Brackman Grade among the Studied Patients
One of the most frequently employed clinical evaluation methods is the H-B facial
nerve grading system. The grades ranges from I (normal) to VI (severe), depending
on the functional impairment (forehead movement, mouth asymmetry, movement, or eye
closure) (no movement). We evaluated the H-B scale, which has been used consistently
in the clinical practice to assess the severity of BP.
In the present study, in the assessments after one and three months, there was a significant
improvement when compared with the assessment performed upon admission. After 6 months,
the rate of grade-I patients was of 81.5%, with an insignificant change when compared
with assessment after 3 months.
Yoo et al.[28] reported that presenting a lower initial H-B grade (II-IV) was strongly related
to complete recovery, which they believed to be the most important factor associated
with a favorable prognosis. This finding was similar to that of previous research
in adults with BP,[38] which found that an initial lower degree of FNP, as measured by the H-B scale, was
related to a better outcome. Yoo et al.[29] reported that BP patients had favorable outcomes at six months when the initial
H-B grade was IV or lower. The facial nerve injury caused mild (grade II) impairment
in 5 individuals and substantial (grade III) dysfunction in 3 patients, per the Lima
et al.[12] study.
Recovery from Facial Nerve Palsy
In pediatric patients, BP appears to recover earlier, and the overall recovery rate
has been reported to be of up to 100%, which is higher than in adults.[17]
In the present study, after 1 month, 15 patients (55.6%) presented complete improvement,
while 3 patients (11.1%), no improvement, while in the third month, 20 patients (74.1%)
were grade I, with significant improvement compared to the assessment after 1 month.
After 6 months with insignificant change when compared with the assessment after 3
months, in which 22 patients (81.5%) showed complete improvement.
In their study, Lima et al.[12] found that, while 3 patients continued to present some degree of FNP at the last
follow-up 30 days following the onset of neurological symptoms, 5 patients recovered
completely. In the study by Gupta et al.,[30] all seven children showed complete recovery.
Twelve case reports and one case series were included in the systematic review by
Gupta et al.,[31] and 16 out of the 20 individuals included had fully recovered from BP symptoms,
whereas 4 had only partially recovered.
Egilmez et al.[32] reported that 31 cases had a history of contact with a COVID-19 patient, and 3 of
those patients had positive COVID-19 RT-PCR results; they found a lower rate of full
recovery: 37.5%.
Relationship between Gender and Recovery from Facial Nerve Affection
In the present study, there was statistically insignificant relationship between age
and recovery at the first, third, or sixth months. The mean age at the onset of BP
was of 6.6 years in a study with 29 children conducted by Chen et al.,[33] and of 9.2 years in a study with 106 children under the age of 15 performed by Jenke
et al.,[34] with no statistically significant difference between genders.
According to Lee et al.,[35] age appears to be a good predictive factor for a quicker recovery from BP in children;
they found no statistically significant correlation regarding prognosis and gender,
the severity of the diagnosis, the affected side, and early or late treatment.
Hogg et al.,[24] reported that the COVID-19 epidemic significantly increased the incidence of pediatric
BP; their sample was composed of more female patients (12) than male patients (5).
Yoo et al.[28] concluded that a lower H-B grade at the initial presentation was the main factor
impacting the full recovery from BP in children. Other factors, such as gender and
age, failed to show any relevance in the prediction of the possibility of complete
recovery.
Aslan et al.[36] found no evident change in terms of gender among their BP patients between the periods
of January 2019 to January 2020 and April 2020 to April 2021.
Relationship between COVID-19 Infection and Recovery from Facial Nerve Affection
The prognosis for BP in children is excellent; most children recover completely within
6 weeks, while some children may need up to 1 year. In general, the incidence of spontaneous
recovery from BP in pediatric populations can reach 97%.[37]
In a 2005 retrospective study, Chen et al.[33] reported a recovery rate of 68.8% after 3 weeks, and of 96.9% after 7 months, in
a population of 29 children in Hong Kong. Moreover, in 2011, Jenke et al.[34] reported that, among 106 children in Germany, 97.6% recovered after 12 weeks, although
only 3.7% of them had taken corticosteroids.
In the present study, there was a statistically insignificant relationship between
COVID-19 infection and recovery in the first, third, or sixth months. According to
the results, it seems that there is no association between COVID-19 infection and
facial palsy; however, the patients infected with COVID-19 in the sample experienced
a rapid, early recovery from BP. However, the present study is limited by the small
sample size.
According to Mutlu et al.,[20] 98% of the patients who were referred to their clinic with idiopathic peripheral
FNP received negative results from a SARS-CoV-2 RT-PCR test, and there was no rise
in the number of patients with this condition during the first year of the COVID-19
pandemic. Moreover, Aslan et al.[36] concluded that they did not observe a relationship between COVID-19 and cases of
BP.
Barron et al.[21] they examined many pediatric cases of FNP in a region of South Wales but were unable
to establish a causal relationship between COVID-19 and pediatric FNP.
Evidence of BP in COVID-19 patients was found in the systematic review by Gupta et
al.,[31] suggesting a potential association with SARS-CoV-2;. 12 case reports and 1 case
series serve as the foundation for this evidence. One of the shortcomings of their
study[31] it is that they did not review a study with large sample size, a prospective study,
or a randomized controlled study.
Moreover, Codeluppi et al.[23] reported that there were more cases of facial palsy during the first year of the
COVID-19 pandemic than there had been during the same time the year before, suggesting
an elevated risk of FNP during or following COVID-19 infection. The fundamental weakness
in their study[23] is that, despite the fact that 21% of the sample from the 2020 cohort displayed
COVID-19 clinical symptoms, 37 out of the 38 included patients were not tested for
SARS-CoV-2. This is why it is incomprehensible that the review and conclusion used
just clinical data and excluded the findings of PCR tests.
Codeluppi et al.[23] should have assessed if there was a link between COVID-19 and FNP in the 1 COVID-positive
patient with facial palsy in their study. The results of nerve conduction studies
(NCSs), brain imaging findings, and cerebrospinal fluid (CSF) findings would be of
particular interest. Before attributing an increased frequency of facial palsy to
the infection, it is critical to establish a causal relationship between COVID-19
and BP. Furthermore, according to Codeluppi et al.,[23] in 2019 there were 2 patients with COVID-19-associated FNP. However, the outbreak
had not yet reached Europe at that point. How do the authors address this contradiction?
The main limitation of the present study was the small sample size; larger cohort
studies and multicenter studies are required to support our findings. Another limitation
to the study is the period of follow-up of facial nerve recovery. We followed up our
patients for up to 6 months. A longer period of follow-up may be required for patients
without recovery of facial nerve function in up to one year.
