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SYSTEMATIC REVIEW
published: 31 March 2020
doi: 10.3389/fneur.2020.00222
Frontiers in Neurology | www.frontiersin.org 1March 2020 | Volume 11 | Article 222
Edited by:
Limor Avivi-Arber,
University of Toronto, Canada
Reviewed by:
Meg E. Morris,
La Trobe University, Australia
Orlando Guntinas-Lichius,
University Hospital Jena, Germany
Adriaan Grobbelaar,
University College London,
United Kingdom
*Correspondence:
Annabelle Vaughan
annabelle.vaughan@health.qld.gov.au
Specialty section:
This article was submitted to
Neurorehabilitation,
a section of the journal
Frontiers in Neurology
Received: 27 September 2019
Accepted: 10 March 2020
Published: 31 March 2020
Citation:
Vaughan A, Gardner D, Miles A,
Copley A, Wenke R and Coulson S
(2020) A Systematic Review of
Physical Rehabilitation of Facial Palsy.
Front. Neurol. 11:222.
doi: 10.3389/fneur.2020.00222
A Systematic Review of Physical
Rehabilitation of Facial Palsy
Annabelle Vaughan 1,2,3
*, Danielle Gardner 1, Anna Miles 4, Anna Copley 2, Rachel Wenke 1,3
and Susan Coulson 5
1Speech Pathology Service, Gold Coast University Hospital, Gold Coast, QLD, Australia, 2School of Health and
Rehabilitation Sciences, University of Queensland, Brisbane, QLD, Australia, 3School of Allied Health Sciences, Griffith
University, Gold Coast, QLD, Australia, 4Speech Science, The University of Auckland, Auckland, New Zealand, 5School of
Health Sciences, Discipline of Physiotherapy, The University of Sydney, Camperdown, NSW, Australia
Background: Facial palsy is a frequent and debilitating sequela of stroke and brain injury,
causing functional and aesthetic deficits as well as significant adverse effects on quality
of life and well-being. Current literature reports many cases of acquired facial palsy that
do not recover spontaneously, and more information is needed regarding the efficacy of
physical therapies used in this population.
Methods: A systematic search of eight electronic databases was performed from
database inception to December 2018. Gray literature searches were then performed
to identify additional articles. Studies were included if they addressed physical
rehabilitation interventions for adults with acquired facial palsy. Reasons for exclusion
were documented. Independent data extraction, quality assessment, and risk of
bias assessment followed the Preferred Reporting Items for Systematic Reviews and
Meta-Analyses (PRISMA) guidelines.
Results: Following abstract screening, a total of 13 full-text articles were identified for
independent screening by two reviewers. This included four randomized control trials,
two non-randomized control trials, one cohort study, and six prospective case series
studies. Twelve out of the 13 included studies reported on facial palsy as a sequela of
stroke. A total of 539 participants received intervention for facial palsy across the 13
included studies. Therapy design, length and frequency of intervention varied across the
studies, and a wide range of outcome measures were used. Improvement on various
outcome measures was reported across all 13 studies. The quality of the evidence was
low overall, and most studies were found to have high risk of bias.
Conclusions: All the studies in this review report improvement of facial movement
or function following application of various methods of physical rehabilitation for facial
palsy. Methodological limitations and heterogeneity of design affect the strength of
the evidence and prevent reliable comparison between intervention methods. Strong
evidence supporting physical rehabilitation was not found; well-designed rigorous
research is required.
Keywords: central facial palsy, rehabilitation, exercise, systematic review, therapy
Vaughan et al. Systematic Review of Facial Palsy Rehabilitation
INTRODUCTION
The facial nerve (CNVII) plays a critical role in multiple complex
functions of human life including mastication, speech, and
successful social communication through expression of mood
and emotion (1–4). Central facial palsy (CFP) results from
damage to the central segment of this nerve (facial nucleus in
the pons, motor cortex, or connections between the two) (5)
and manifests typically as a unilateral impairment of movement
opposite to the side of the injury, with predominance in the
lower face (6). In contrast, peripheral facial palsy (PFP) results
from injury or damage to extratemporal segments of the facial
nerve (7), for example in idiopathic “Bell’s” palsy, surgery such as
mastoidectomy, or inflammation such as herpes zoster (Ramsay
Hunt syndrome) (8).
CFP is a frequent initial symptom in patients after stroke and
other neurological injury. A study conducted by Cattaneo and
Pavesi (9) found that 60% of patients with first-time ischemic
cortical stroke (MCA and ACA territories) presented with CFP.
Other studies of stroke populations have reported a prevalence
of approximately 45% (6). It is evident from multiple searches
of libraries and online evidence repositories during clinical
management of CFP that most of the available literature relates
to rehabilitation of peripheral facial palsy (PFP), and there is very
little evidence available to guide therapists working with people
suffering from CFP. Whilst systematic reviews have evaluated
physical rehabilitation and other management for PFP (10–12),
the different etiopathogenesis of CFP suggests that rehabilitation
approaches should be specifically modified for this group (13).
Spontaneous recovery of CFP has been reported in two-thirds
of people at 6 months post-stroke, with approximately one-
third of patients after stroke continue to present with persisting
facial palsy after 6 months (14). More recently, differing opinions
are emerging in the literature regarding rates of spontaneous
resolution of CFP (including associated functional and QOL
deficits), with some authors noting that in the absence of
rehabilitation, symptoms seem unlikely to improve (15). In their
study, Volk et al. (6) reported that a high percentage of patients
continued to present with CFP 3 weeks post-onset, and over 60%
of these patients were discharged from sub-acute rehabilitation
with deficits persisting for more than 41 days post-stroke. As the
available literature suggests that CFP can persist past the initial
acute phase of stroke and not resolve spontaneously, people
with CFP may benefit from access to a specific rehabilitation
program aimed at maximizing recovery of facial movement and
function (6,13,16).
Facial palsy can be distressing and debilitating for those
affected, causing both functional and aesthetic deficits (16).
Functional deficits may be characterized by facial asymmetry and
weakness of the lower half of the face, drooping of the corner
of the mouth, dribbling from the corner of the mouth at rest
or during oral intake, reduced masticatory force and efficiency,
asymmetrical smile and dysarthria (slurring or reduced clarity of
speech) (15). It is well-recognized in the literature that in addition
to functional deficits, facial palsy has a negative effect on quality
of life (QOL) and emotional well-being (7,17–21). In their 2016
study comparing QOL between individuals with pure CFP post
stroke vs. pure dysarthria, Chang et al. (21) found that the CFP
group had significantly worse scores on QOL and depression
scales. Interestingly, it has been found that the presence of facial
palsy alone regardless of its severity has a detrimental effect on
the psychological well-being of those who experience it (19).
Rationale
Currently, there is minimal evidence available to guide clinical
decision-making in the rehabilitation of CFP (22,23) and very
little information available regarding the effectiveness of popular
intervention techniques (21,23). As mentioned above, CFP may
not resolve spontaneously and the negative impacts of CFP
on people who experience this disorder can be wide-ranging.
Rehabilitation may maximize functional recovery and improve
the quality of life and psychological well-being of people with
CFP (6,13,16) however there is currently no comprehensive
or systematic review of the literature specific to this disorder
to inform therapy planning and provision. This has significant
implications for patient management, as it is still not clear to
health professionals whether physical rehabilitation techniques
work, or which technique is most effective.
Objective
The purpose of this review is to identify and examine the
available literature specifically relating to physical rehabilitation
of CFP. This review aims to (1) identify the types of physical
rehabilitation methods used in remediation of CFP, (2) review
the effectiveness of various methods of physical rehabilitation,
and (3) review the methodological quality of the studies retrieved.
The findings will be pertinent to clinicians working with patients
with CFP as this is the only review that the authors are aware of
that systematically evaluates the evidence base for rehabilitation
of this disorder.
Research Question
What is the effectiveness of physical rehabilitation for acquired
central facial palsy in adults?
METHODS
Study Design and Search Strategy
This review follows the Preferred Reporting Items for Systematic
Reviews and Meta-Analyses (PRISMA) statement. The review
protocol is registered on PROSPERO (CRD42018115303). A
systematic search strategy was devised in conjunction with a
senior librarian, using the core concepts of facial paralysis,
central nervous system disease, and physical rehabilitation.
The Medical Subject Headings (MeSH) database was used to
obtain terms that were related to these concepts to ensure
a comprehensive search of the literature was performed. The
search strategy was designed and performed using Medline
(Ovid) terminology (see Appendix 1). No limitations were used
for year published, language, or publication type. The search
strategy was then translated for searching the following databases:
Embase (Elsevier), CINAHL (Ebsco), Cochrane Central Register
of Controlled Trials, Proquest Dissertations and Theses Global,
PEDro, Speechbite, and Web of Science (Clarivate).
Frontiers in Neurology | www.frontiersin.org 2March 2020 | Volume 11 | Article 222
Vaughan et al. Systematic Review of Facial Palsy Rehabilitation
Gray literature searches included searches of WHO ICTRP
(3) and ANZCTR (0) using the terms central facial pa∗,with
no completed studies (3 currently registered trials) retrieved.
ClinicalTrials.gov was searched using the heading facial palsy
with 18 completed studies retrieved, however all retrieved studies
either pertained to peripheral facial palsy or did not have
results available and were therefore not included in this review.
Clinical practice guidelines and best practice statements were
searched for relevant literature/references, including Clinical
Guidelines for Stroke Management 2017 (24), United Kingdom
National Clinical Guideline for Stroke (25), and American Speech
and Hearing Association Evidence Maps (https://www.asha.org/
MapLanding.aspx?id$=$8589947062).
Further hand-searching of library and clinical databases were
conducted. Specialists from facial therapy services in Australia
and internationally were asked to provide any relevant literature
which informs their current clinical practice. The reference lists
of articles eligible for inclusion following full text screening
were searched, and any titles that appeared to fit the criteria set
were retrieved.
Participants, Interventions, Comparators
The inclusion and exclusion criteria for the review are presented
in Table 1.
Systematic Review Protocol
The systematic search strategy is presented in Figure 1. A senior
health service librarian performed database searching. Articles
retrieved in the database searches were deduplicated using the
Bond University CREB SRA deduplicating tool (http://crebp-
sra.com) and then further screened to remove other duplicates.
Abstracts of all articles remaining following deduplication were
then collated into an Endnote library, which was then uploaded
TABLE 1 | Selection criteria.
Selection
Criteria
Inclusion Criteria Exclusion Criteria
Participant Adults with acquired CFP Pediatrics (<18 yrs)
Intervention Physical rehabilitation of CFP Surgical or pharmacological
intervention with no physical
rehabilitation component
Comparator None or placebo treatment,
drug/surgical treatment, or
other physical rehabilitation
No outcomes reported
Outcomes Quantitative or qualitative
outcomes in subjective or
objective measures of motor
function or
symmetry/appearance or QOL
Other:
Methodology
Case series
Separate data for CFP
and PFP
Single case study design,
secondary research (i.e.,
reviews)
Combined data for CFP and
PFP or unclear delineation
Other:
Publication
details
Articles from research journals
Articles in English
Book chapters, thesis
publications, opinion pieces
Articles not in English
to Covidence (Veritas Health Innovation Ltd, Melbourne,
Australia) for blind review by two independent reviewers
(AV and DG). Titles and abstracts were screened against the
predetermined inclusion/exclusion criteria and subsequently
added to full text screening lists. Articles included by both
independent reviewers and articles that were marked as “maybe”
by one or both reviewers were considered eligible for further
review. Full texts of eligible studies were then retrieved and
independently assessed for inclusion/exclusion. Any conflicts
that arose during eligibility assessment were resolved by (a)
discussion between reviewers, or where agreement could not be
reached, by (b) discussion with the review team and relevant
experts in the field.
Data Extraction
For all included articles, a range of variables including study
population/participant details, selection criteria, methodology,
interventions (therapy approach, intensity, follow-up) and
outcomes were extracted and are presented in a descriptive
summary in Table 2. These variables were identified as most
relevant to our clinical question. Data extraction was performed
initially by the second author (DG), and then amended and
expanded where necessary by the first author (AV) using
Google Sheets (Google, CA, USA). Due to heterogeneity
in the included studies a meta-analysis was not able to
be performed.
Quality Assessment
Risk of bias was assessed using tools appropriate to the study
methodology determined during the data extraction process:
case series reports were assessed using the JBI Critical Appraisal
Checklist for Case Series (35), cohort studies were assessed using
the JBI Critical Appraisal Checklist for Cohort Studies (35), and
control trials were assessed using the Physiotherapy Evidence
Database—Psychbite scale (PEDro-P) (36). No mixed-method
studies were identified during the search, therefore the tools used
to assess risk of bias were altered from the original PROSPERO
protocol to be more appropriate to the various study designs
retrieved (control trials, case series, cohort study). Risk of bias
analyses were performed independently by two reviewers (AV
and RW) and discrepancies were discussed by the two authors
until consensus was achieved.
Data Analysis
Meta-analysis of the results was not indicated due to the
clinical diversity of the studies retrieved, as recommended
by the Cochrane Handbook for Systematic Reviews of
Interventions (37). Each of the studies retrieved described
differing experimental designs, treatment protocols, and
methods of outcome measurement, and there was inadequate
reporting of data and statistics necessary for appropriate and
meaningful meta-analysis. Types of physical rehabilitation used
in CFP have been broadly grouped as having used either an
active approach (recipients actively move their own muscles or
structures to perform exercises or volitional muscle movements),
passive approach (movement is facilitated by external force,
person or device e.g., massage/stretching, acupuncture, electrical
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Vaughan et al. Systematic Review of Facial Palsy Rehabilitation
FIGURE 1 | Preferred reporting items systematic reviews and meta-analyses (PRISMA) flow diagram detailing search strategy and selection criteria.
stimulation), or a combination of the two. The effectiveness of
physical rehabilitation has been determined by the examination
of the reported results in those studies that provided sufficient
data and is discussed in the context of the various grouped
approaches. Rating of the overall quality of the evidence has
been performed by applying relevant sections of the Grades of
Recommendation, Assessment, Development, and Evaluation
(GRADE) approach to individual studies (38).
RESULTS
Study Selection
The results from database searching and selection processes are
shown in Figure 1.
Study Characteristics
Six case series (total no. of subjects =108) one cohort study (total
no. of subjects =112), and six control trials (total no. of subjects
=133) were identified. Methodological details are outlined
in Table 2. Of the four RCTs, two appeared to use identical
participant populations and outcome data and are subsequently
discussed as one study in parts of this review (n=99 (13,16). All
the included studies used a pre-test post-test design.
Participant Demographics
Participant demographics for all included studies are reported in
Table 2. Twelve out of the 13 included studies reported on facial
palsy as a sequela of stroke, and one study reported facial palsy
secondary to acquired brain injury. A total of 539 participants
received intervention for facial palsy in the 13 studies included in
this review (age range 48–88 yr old). There was a large range in
time post-onset of facial palsy from acute (e.g., “days”) to chronic
(e.g., 6–10 years) stages of recovery.
Types of Physical Rehabilitation for Facial
Palsy
There was a high degree of heterogeneity in physical
rehabilitation methods described for adults with CFP. Seven
studies reported interventions aimed at remediation of facial
palsy as their primary objective (6,26–29,31,33), and six
reported targeting lip function or movement in the context
of post-stroke dysphagia therapy (13,16,23,30,32,34). Four
studies reported on active intervention methods for remediation
of oromotor function or facial palsy (23,26–28); two used
muscle strengthening exercises alone (26,27) and the other
two used biofeedback (via mirror or device) while performing
orofacial exercises (23,28). Four studies reported on passive
intervention techniques such as massage, stretching or electrical
stimulation for the remediation of facial muscle strength or facial
palsy (13,16,29,30). Acupuncture is classified in this review
as passive rehabilitation; one study (30) reported on the use of
scalp acupuncture compared to a group that received “western
medicine.” Five studies combined active and passive approaches
in the rehabilitation of CFP (6,31–34); therapy varied across
these studies but all included elements of active exercise, massage,
stretching or passive manipulation, or application of various
devices (Table 2).
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Vaughan et al. Systematic Review of Facial Palsy Rehabilitation
TABLE 2 | Extracted data.
Study ID
[References]
Participants
N Dx time
post onset
Methodology Interventions Intensity
length of Tx freq
duration
Outcome measures Results
Group A Group B
Hagg and
Anniko
(26)
30 (24 with
UFP) Stroke 2
days−10yrs
Retrospective
case series
Active
Therapy
Lip muscle training N/A >5 weeks 3 ×3/day
5–10 s
Swallowing capacity (ml/s) Lip force Stat sig improvement in both OMs
(p<0.05) FP ’improved’
Hee-Su et al.
(27)
10 Stroke <6
mths
Prospective
case series
Traditional therapy +
resistance training of OO
N/A 4 weeks 5×/wk not
stated
Orbicularis oris strength Lip closure
(VDS)
Stat sig improvement in both OMs
(p<0.05)
Huffman
(28)
4 Brain injury
>2 mths
Prospective
non-
randomized
control trial
Mirror therapy Mirror therapy +
EMG
10 days (in 2 week
period) Daily 30min
Muscle grade Improvement in both pairs although
3×greater in EMG vs. mirror
Kang et al.
(23)
21 Stroke
<12 wks
Prospective
RCT
Orofacial exercises Orofacial
exercises +
mirror therapy
14 days 2×/day
15 min
HBGS Facial movement difference
(m-dif) Facial movement ratio (m-rat)
Stat sig improvement in all OMs
(p<0.05), greater in mirror vs. control
Choi
(29)
9 Stroke <3
mths
Prospective
case series
Passive
Therapy
Neuromuscular ES +
dysphagia therapy
N/A 4 weeks 5×/wk 30
min/session
Max cheek strength (MCS) Max lip
strength (MLS) Dysphagia (VDS)
Stat sig improvement in MCS and
MLS Stat sig decrease on VDS
(p<0.05)
Konecny et al.
(16)
99 Stroke
1-2wks
Prospective
RCT
SSRI, SP/OT/PT SSRI, SP/OT/PT
+orofacial
therapy
4 weeks Daily not
stated
HBGS Distance measure BDI-II Stat sig improvement in all OMs
(p<0.05), greater in experimental vs.
control
Konecny et al.
(13)
99 Stroke
1–2wks
Prospective
RCT
SSRI, SP/OT/PT SSRI, SP/OT/PT
+orofacial
therapy
4 weeks Daily not
stated
As above +Bartel index Mod. Rankin
score
Stat sig improvement in both QOL
OMs (p<0.05), greater in
experimental vs. control
Zhou and Zhang
(30)
165 Stroke
1day−6yrs
Prospective
RCT
Scalp acupuncture Western
medicine
24 days? Daily
∼50 min
Clinical indexes / function grading
scales
Improvement in 88.57% of
acupuncture group and 76.67% of
western medicine group
Hagg and
Larsson
(31)
7 Stroke 6
mths−4 yrs
Prospective
case series
Combination
Therapy
Body regulation, manual
orofacial regulation,
palatal plate activation +
velopharyngeal closure
training
N/A 5 weeks 5×/wk 120
min/session +HEP
Swallowing capacity (ml/s) Meal
observation Oral motor performance
Orofacial sensory function
Velopharyngeal closure VFSS
Self-assessment
Improvement on raw scores in at
least one variable for all OMs
Hagg Tibbling
(32)
31 Stroke
Days−10 yrs
Prospective
non-
randomized
control trial
Palatal Plate (PP) Oral IQoroR
screen (IQS)
3 months 3×/day
PP 10–30min; IQS
30 s
Swallowing capacity (ml/s) Facial
Activity Testing (FAT)
Stat sig improvement in both OMs for
both groups (p<0.05) Improvements
maintained at 1 yr f/up
Noor et al.
(33)
50 Stroke Not
stated
Prospective
case series
Massage, ES, KOBAT N/A ?3 weeks 3×/wk
not stated
Spasticity grade Reduction in spasticity grade for all
participants
Van Gelder et al.
(34)
2 Stroke
2mths
Prospective
case series
Neuro Developmental
Treatment
N/A 9–12 weeks Weekly
not stated
Mimic expressions Orofacial function
Asymmetry and adequacy
2/2 improved mimic expressions +
symmetry 1/2 improved orofacial
function +adequacy
Volk et al.
(6)
112 Stroke 20
days (median)
Prospective
cohort study
Physical training of related
muscles, tapping, mirror
therapy
N/A 21 days (median)
not stated not stated
Bartel index HBGS Sunnybrook FGS
Stennert index Action units (AU) FaCE
questionnaire FDI
Stat sig improvement in activity, facial
nerve motor function, self-reported
non/motor abilities (p<0.05)
Dx, Diagnosis; EMG, Electromyography; ES, Electrical stimulation; HBGS, House Brackmann Grading Scale; FGS, Facial Grading System; FDI, Facial Disability Index; FP, Facial palsy; HEP, Home exercise program; OM, Outcome
measures; OO, Orbicularis oris; OT, Occupational therapist; PT, Physiotherapist; QOL, Quality of life; SP, Speech pathologist; SSRI, Selective serotonin reuptake inhibitor; Tx, Therapy; UFP, Unilateral facial palsy; VDS VFSS, Dysphagia
Scale; VFSS, Videofluroscopic Swallow Study.
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Vaughan et al. Systematic Review of Facial Palsy Rehabilitation
Dosage
Length and frequency of therapy varied across the studies, with
participants receiving multiple therapy sessions per week for
between 10 days and 9 weeks. Details relating to intensity of
therapy (length, frequency, and duration of intervention) are
presented in Table 2.
Outcome Measures
A wide range of outcome measures for muscle strength and
facial movements were used including measures of muscle
strength, facial movement, and symmetry; details are outlined
in Table 2. No validated outcome measurement tools were used.
The majority of studies did not provide detailed descriptions
of grading scales; only three studies (6,13,16,23) used well-
known outcome measures specific to facial palsy. Facial palsy
was often measured in conjunction with other deficits of speech,
swallowing, emotional and psychological well-being.
Effectiveness of Physical Rehabilitation of
Facial Palsy
Four RCTs and nine observational studies reported
improvements in various measures of facial palsy or facial
motor function, which are outlined below in the context of the
rehabilitation approach used (active, passive or combination).
Eight of the 13 studies included comments about the statistical
significance of the results (p-values), however none performed
calculations of effect size, and therefore none of the studies
provided sufficient data to assess imprecision or inconsistency as
outlined in the GRADE approach. There were also insufficient
data reported to facilitate judgement of indirectness; the nine
observational studies do not undertake comparison with an
alternative therapy or control group, and none of the RCTs
provided calculations of risk ratio or effect size that would enable
meaningful direct comparison.
Active Therapy
Four studies reported on active therapy methods; one RCT (23),
one nRCT (28), and two case series’ (26,27). All four studies
reported improvements in treatment variables measured. Kang
et al. (23) reported improvement in HBGS scores and functional
measures (facial movement ratios) in both the control group
and the experimental group (both groups performed the exercise
protocol with the experimental group receiving mirror feedback
as the experimental condition). Huffman (28) also reported
improvement in all subjects on an unvalidated ‘muscle grade’
rating scale mentioned but not detailed by the authors; as well
as improvements three times greater for the subjects receiving
EMG feedback compared to mirror feedback. Both the case series’
implemented protocols of lip strengthening using instrument-
based exercise. Hee-su et al. (27) reported improvements in
orbicularis oris muscle strength and lip closure function during
swallowing; no outcomes specific to facial palsy (e.g., measures of
movement or symmetry) were used. Hagg and Anniko (26) also
reported improvement in raw scores of lip force from baseline
measures taken using a Lip Force Meter instrument however did
not specifically report on outcomes for facial palsy.
Passive Therapy
Four studies reported on passive therapy methods, including a
case series study (29) and three RCTs (13,16,30); two RCTs
are discussed together (13,16) for reasons mentioned previously.
All four reported improvements in relevant measures. Choi (29)
reported changes in facial muscle strength compared to baseline
measures however did not explicitly report outcomes for facial
palsy. Zhou and Zhang (30) reported a larger change in all
outcome measures (including a facial movement grading scale
not described in the study) for the group receiving acupuncture
compared to those receiving “western medicine.” There was no
detail provided regarding the method for administration of this
grading scale. Konecny et al. (13,16) reported improvements in
formal facial nerve assessment measures (HBGS) as well as in a
variety of other functional and quality-of-life scales.
Combination Therapy
Five studies reported on therapy protocols that combined passive
and active methods (e.g., massage/manipulation with active
exercise regime). These included three case series’ (31,33,34),
one non-randomized control trial (32) and one cohort study
(6). One case series (33) reported improvements in spasticity of
facial muscles; this was demonstrated by reporting the number
of participants per scoring level (grade I–V) pre and post
treatment on an unnamed grading tool. There were no individual
assessment outcomes reported and there was an absence of
statistical analysis of the data. One (31) reported improvements
in raw scores of orofacial motility on an informal four-point scale
as well as improvement in mean severity score of oral motor
performance. The authors provided raw pre and post assessment
data for each participant as rated by multiple assessors; there was
an absence of further analysis of this data and overall outcomes
were focused on dysphagia rather than facial palsy. The case series
reported by Volk (6) reported improvements in three well-known
tools to assess facial palsy [HBGS (39), Sunnybrook Grading
Scale (40), and Stennert Index (41)], two validated quality of
life instruments [FaCE Questionnaire (42) and FDI (43)], and
a system of automated facial movement analysis described in
the study.
Maintenance of Therapeutic Effects
Eleven of the 13 included studies did not report any follow
up assessment, and therefore no evaluation of the maintenance
of therapeutic effects was available. One study (32) reported
maintenance of improved facial activity at follow-up assessment
at least 1 year post treatment in both groups. Van Gelder et al.
(34) reported on follow-up assessment 9 weeks post treatment in
only one of the two participants. Their results showed a decline
in function between completion of treatment and re-assessment,
which the authors interpreted as showing treatment effects were
not maintained.
Methodological Quality and Risk of Bias
A summary of the consensus ratings for methodological
assessment is shown using modified harvest plots, which have
been used previously in systematic reviews to present data that
is not able to be graphed using traditional methods (44,45).
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Vaughan et al. Systematic Review of Facial Palsy Rehabilitation
TABLE 3 | PEDro-P and JBI ratings.
Condensed
category
PEDro-P Item Condensed
category
JBI item (Case series) Condensed
category
JBI item (Cohort)
Participant Eligibility criteria specified
Concealed allocation
Participant Eligibility criteria specified
Standard, reliable measurement of
condition
Valid identification of condition
Participant Both groups similar, recruited
from same population
Intervention Prognostic similarity at baseline
between intervention groups
Design Consecutive inclusion
Complete inclusion
Participant demographics
Participant clinical information
Outcomes or follow-up
Design Exposures measured similarly
Standard, reliable measurement
of exposure
Confounding factors identified
Groups/participants free of
outcome initially
Outcome measurement valid
and reliable
Blinding Subject blinding
Therapist blinding
Assessor blinding
Outcomes >85% of the subjects followed up for
at least 1 key outcome
Intention-to-treat analysis
Between group statistical analysis for
at least 1 key outcome
Site Site demographics Follow-up Follow up sufficient and reported
Complete follow up
Incomplete follow up managed
Variability Point estimates of variability provided
for at least 1 key outcome
Statistics Appropriate statistical analysis Statistics Appropriate statistical analysis
These modified harvest plots were created by grouping similar
criteria together for each appraisal tool, as detailed in Table 3.
As in previous studies where modified harvest plots have been
used, methodological quality is represented by bar height (45).
“Unclear” consensus ratings have been scored as zero when
calculating scores for each criterion on the JBI tools.
Control Trials
Across the control trials, scores on the PEDRO-P ranged from
3 to 9 with an average of 5.5 out of 11 (see Figure 2). Of the
RCTs, 2 of the 4 specified eligibility criteria for inclusion in the
study, and while the majority allocated subjects randomly to
interventions only one concealed this allocation. Blinding was
an area of significant risk across the RCTs, with 1 of 4 studies
blinding subjects and assessors and no blinding of therapists in
any study. The nRCTs showed similar shortcomings in allocation
and blinding items. The intervention groups were similar at
baseline regarding the most important prognostic indicators in
>90% of the studies. Outcome measurement was an area of
strength for all the control studies; 100% obtained measures of at
least one key outcome from >85% of subjects and demonstrated
that all subjects for whom outcome measures were available
received the treatment or control condition. Overall the quality of
the control trials is low due to the significant limitations present
in the majority of studies.
Case Series and Cohort Study
Scores on the JBI tool for case series evaluation ranged from 2 to
7 with an average of 3.8 out of 10 (see Figure 3). Four (27,29,33,
34) of the six case studies were judged to be at high risk of bias;
2 of the 6 of studies failed to outline clear criteria, only 30% used
valid methods for identification of the condition, >80% did not
report consecutive recruitment of subjects and failed to clearly
report clinical information of the participants. Two case studies
were judged to have an unclear risk of bias (26,31); strengths of
both these studies were found in reliable condition measurement
and clear reporting of participant demographics. Limitations of
the case series’ judged as “unclear risk of bias” were varied—
in one (31) it was not clear if the study included consecutive
and complete inclusion and methods of statistical analysis were
ambiguous; in the other (26) criteria were not clearly defined and
it was not possible to determine if valid methods for identification
of the condition were used.
DISCUSSION
This review has shown that despite trends demonstrating
improvement in CFP following various types of physical
rehabilitation, there is a lack of high-quality evidence currently
available to inform clinical practice. Many questions remain for
clinicians planning and providing therapy for this population.
Literature is emerging which recognizes CFP as an impairment
in its own right (separate to its impact on speech or swallowing
function), and therapies specifically targeting this disorder are
being investigated with increasing frequency. All the studies in
this review report improvement on various parameters of facial
movement or function and, although lacking in rigor, indicate
potential benefit from using physical rehabilitation approaches.
Effectiveness of Therapy
Improvement in facial muscle strength or movement was
reported across all 13 studies, and positive changes in other
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Vaughan et al. Systematic Review of Facial Palsy Rehabilitation
FIGURE 2 | Study identification number: 1. (32) 2. (28) 3. (23) 4. (16) 5. (13) 6. (30) Max. indicates the highest possible score that an article could receive in each
category.
FIGURE 3 | Study identification number: 7. (29) 8. (28) 9. (26) 10. (27) 11. (33) 12. (34) 13. (6) Max. indicates the highest possible score that an article could receive in
each category.
outcome measures such as swallow function and quality of
life were also shown (where measured). Only one study
provided data for maintained effects of therapy at >1 year post
intervention (32), and while this study had comparative strengths
in methodology, its lack of overall rigor reduced the strength
of the data. All 13 studies reported statistically significant
improvements from baseline measures, however none performed
calculations of optimal sample size or treatment effect measures.
It is therefore unclear if the improvements reported can be
attributed to the physical therapy provided or if other variables
influenced the outcomes. Overall, the studies included in this
review provide insufficient evidence to draw strong conclusions
regarding the effectiveness of physical rehabilitation for CFP.
Comparison of the effectiveness of differing therapy
approaches remains unclear following this review. Of the
four studies that were found to be the most methodologically
sound (as per risk of bias assessments), two provided active
therapy (one involved strengthening exercises only) (23,26), one
provided passive therapy (16), and one described a combination
of these two approaches (32). Active and passive approaches
were explored by only a small number of methodologically
weak RCTs, and there were no RCT designs that investigated
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Vaughan et al. Systematic Review of Facial Palsy Rehabilitation
a combination of approaches. As well as insufficient reporting
of treatment effect size or precision, there was a large amount
of variation in all aspects of the design of the studies—each
study described different participant variables (e.g., time post
onset), dosage and treatment duration. These factors restrict
any meaningful comparison being made between outcomes,
which leads to a lack of support for one method of rehabilitation
over another.
This review highlights the need for further well-designed
and rigorous research to examine the efficacy of physical
rehabilitation of CFP. The trend of improvement across various
outcome measures reported in all studies provides some
indication that physical therapy may be of benefit, however
overall there were significant limitations that impact on confident
application of these findings to current clinical practice. These
include a lack of comprehensive reporting and analysis of data
in all studies, and methodological limitations (e.g., lack of RCT
designs, lack of concealed allocation, minimal use of blinding,
and lack of follow-up assessment). The majority of studies also
failed to use standardized, reliable outcome measurements, which
creates questions about the validity of findings and makes any
comparison of outcomes difficult. Future studies should aim
for more rigor in their design, for example by using RCTs to
minimize risk of bias and strengthen the validity of findings
and including follow-up assessment to measure maintenance of
therapeutic effect.
Assessment
A major challenge for evaluation of methods of physical
rehabilitation of CFP is the heterogeneity of assessment tools
(and subsequently outcome measures) described. Only four of
the 13 included studies utilized any standardized method of
assessing facial palsy (6,13,16,23,32) and only three of these
used widely-accepted quantitative outcome measures (6,13,16,
23). The remainder of the studies described a variety of informal
clinical measures of muscle strength or facial movement and
function. As such, comparison of findings between the studies in
an effort to establish which methods were more effective is not
able to be reliably performed.
Clinical Implications
Positive trends in favor of physical rehabilitation were found. All
the studies retrieved by this review process do appear to show
improvements in facial palsy with rehabilitation, which lends
support to the rationale for continuation of therapy provision
as well as ongoing research. The strength of the evidence is low
overall, which should be considered when planning intervention
for this population.
Future Directions
Future studies should aim to use objective and standardized
assessment tools. Objective assessment of facial palsy is
notoriously difficult (42,46). Due to the lack of published,
validated assessment tools available specific to CFP, further
validation of tools designed for broader use (including peripheral
types of facial palsy) may be indicated. Literature specific to
PFP recommends use of the Sunnybrook Facial Grading System
(40), and the House-Brackmann Grading Scale (39), and these
tools have been used with some effectiveness to measure CFP
in studies by Volk et al. (6), Kang et al. (23), and Konecny
et al. (13,16). There are limitations in both tools including
subjective ordinal grading systems with limited items (47,
48). The Electronic Facial Paralysis Assessment (eFACE) was
developed to provide clinicians with a tool that “has greater
sensitivity and objectivity when assessing incomplete paralysis
and post-interventional improvement. . . in cases of both acute
peripheral nerve palsy and recovery” (49). This tool has been
found to have high test-retest reliability (50), have high validity
and reliability (49), and had positive feedback from a panel of
international facial nerve experts (51). The tool needs further
validation in a CFP population. In addition to measuring facial
function, the inclusion of reliable outcome measures that evaluate
the emotional and psychological impact of CFP would enable a
broader assessment of the holistic impacts of rehabilitation. Two
examples of validated patient-graded tools that are referenced
in current CFP literature are the Facial Clinometric Evaluation
(FaCE Scale) (42) and the Facial Disability Index (FDI) (43).
Studies of CFP should include use of one of these tools, as non-
motor impacts of facial palsy have been shown to be as important
as motor function to people with this impairment (52).
It would be beneficial to have a comprehensive picture
of current clinical practice to incorporate into future studies.
Clinical physiotherapists and speech pathologists provide
rehabilitation for CFP for using principles derived from
peripheral nerve damage literature due to the lack of studies
specific to CFP, despite these therapies also having low quality
supporting evidence (12) and varying significantly in mechanism
of impairment. A comprehensive survey of current practice
would enable “expert opinion” to be integrated into the
development of a gold standard of evidence-based physical
rehabilitation, along with stronger evidence from well-designed
clinical trials.
Exercise-based physical rehabilitation for facial palsy must
be performed in a controlled and precise manner, and repeated
sufficient times to induce long-term synaptic change (53). These
exercises are often performed using some method of biofeedback
(e.g., mirror); primarily relying on the visual system to obtain
accurate proprioceptive information about position of facial
muscles during slow, controlled movements that focus on
symmetry (54). Without some form of external proprioceptive
feedback, it is extremely difficult for patients to precisely
and effectively judge and monitor the movements of facial
structures (54). Exercise protocols can therefore be difficult for
people to perform accurately if they have concomitant visual-
perceptual, cognitive or behavioral changes secondary to stroke.
Well-designed research which evaluates the effectiveness of
interventions which are accessible to a wider clinical population
would be of great benefit to people suffering from central facial
palsy whose other impairments prevent them from engaging in
strict exercise-based protocols. Regardless of the intervention
strategy employed, clear and detailed reporting should be
ensured to enable replicable therapeutic protocols.
Further investigation of physical rehabilitation methods for
CFP is required to determine effective types and approaches for
therapy and to guide clinical decision-making. There is a gap in
services currently available for people wishing to access therapy
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Vaughan et al. Systematic Review of Facial Palsy Rehabilitation
for CFP and is not possible to base a strong case for clinical input
on the current literature, even though trends have been identified
that indicate potential benefit of physical rehabilitation.
LIMITATIONS
Although every effort was made to ensure database and other
searches were comprehensive it is possible that some records
were not retrieved via the search methods. Due to the difficulties
and cost associated with obtaining verified and reliable document
translation, this review was unable to include articles where the
full text was not available in English. This may have resulted
in some studies being missed; the authors are aware of at least
one non-English study (14) which may have contributed toward
this review. Our systematic review also had limitations relating
to methodological quality and available data in the existing
literature; only four RCTs were retrieved, which were of low
quality, and the observational studies all lacked sufficient data
to draw strong conclusions or perform calculation of treatment
effect size. It is recognized that in many areas of health care, some
interventions are supported by evidence from RCTs and others
are not (55). It is also acknowledged in medical research literature
that decision-making is often necessary even when there is
imperfect evidence (56). As clinicians who provide assessment
and therapy to patients with central facial palsy, we included the
smaller observational studies due to a lack of larger or more well-
designed trials—as per Balshem et al. “in the absence of high-
quality evidence, clinicians must look to lower quality evidence
to guide their decisions” (57). While we are aware that the
limitations in methodology affect the reliability of these studies,
and thus also affect the strength of recommendations that can be
drawn from their findings, the reality is that there are not enough
large well-designed RCTs available to rely solely on this level of
evidence for clinical decision-making and intervention.
CONCLUSIONS
The studies in this review report improvement of facial
movement or function following application of various methods
of physical rehabilitation for CFP. Methodological limitations
and heterogeneity of design affect the strength of the evidence
and prevent reliable comparison between intervention methods.
Strong conclusions regarding the effectiveness of intervention
cannot be drawn using the studies identified by this review as
good quality, robust evidence supporting physical rehabilitation
of central facial palsy was not found.
DATA AVAILABILITY STATEMENT
The datasets generated for this study are available on request to
the corresponding author.
AUTHOR CONTRIBUTIONS
AV and DG conceived the idea for this review. AV, DG, RW,
AM, and SC formulated the question for review and designed the
search strategy. AV and DG performed the abstract screening,
full text review, and extracted data from included studies. AV
and RW performed the risk of bias assessments. AV analyzed
and interpreted the data and drafted the manuscript. AC and AM
provided overall supervision of the project and final approval of
the version to be published. All authors provided critical feedback
and helped shape the research, analysis, and manuscript.
FUNDING
This study was undertaken with support from a Gold Coast
Health Allied Health Clinical Backfill for Research grant, which
provided AV and DG with four weeks of funded offline time.
Assistance with funding open-access publication was granted via
the Gold Coast Health Study, Education and Research Trust.
ACKNOWLEDGMENTS
The review team thanks Sarah Thorning for her valuable
assistance with database searching and deduplication of search
results. We also thank the Speech Pathology and Audiology
Service (Allied Health Services|Gold Coast Health).
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Conflict of Interest: The authors declare that the research was conducted in the
absence of any commercial or financial relationships that could be construed as a
potential conflict of interest.
Copyright © 2020 Vaughan, Gardner, Miles, Copley, Wenke and Coulson. This is an
open-access article distributed under the terms of the Creative Commons Attribution
License (CC BY). The use, distribution or reproduction in other forums is permitted,
provided the original author(s) and the copyright owner(s) are credited and that the
original publication in this journal is cited, in accordance with accepted academic
practice. No use, distribution or reproduction is permitted which does not comply
with these terms.
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Vaughan et al. Systematic Review of Facial Palsy Rehabilitation
APPENDIX
Search Strategy (Example)
Database: Ovid MEDLINE(R) ALL <1946 to December 31, 2018>
——————————————————————————–
1. exp Facial Paralysis/ (11721)
2. ((facial or orofacial or oro-facial) adj3 (paralys∗or paresis or
droop∗or palsy or asymmetr∗or impair∗)).tw. (14536)
3. ((facial or orofacial or oro-facial) adj3 (express∗or nerve∗or
muscle∗or move∗or reanimat∗)).tw. (26746)
4. or/1-3 (38981)
5. exp Physical Therapy Modalities/ (140199)
6. (exercis∗or therap∗or physiotherap∗or rehabilit∗
or retrain∗or train∗or treat∗or manag∗or
intervention∗).tw. (7745138)
7. (mime∗or miming or mirror∗or tap∗or massag∗or
stretch∗or acupunctur∗or needling∗or biofeedback or
neuromuscular∗or kinesio∗or cryo∗).tw. (382977)
8. (electric∗adj2 stimul∗).tw. (62989)
9. (e-stim∗or electromyograph∗or semg).tw. (39537)
10. or/5-9 (8084566)
11. 4 and 10 (15595)
12. exp Central Nervous System Diseases/ (1342443)
13. (central nervous system adj2 (diseas∗or injur∗or
infect∗)).tw. (9406)
14. upper motor neuron.tw. (1424)
15. stroke∗.tw. (218936)
16. brain injur∗.tw. (57635)
17. tbi.tw. (21035)
18. (central adj3 (facial.tw. adj2 (paralys∗or paresis or palsy or
palsies))).tw. (144)
19. or/12-18 (1463675)
20. 11 and 19 (1970).
Frontiers in Neurology | www.frontiersin.org 13 March 2020 | Volume 11 | Article 222
