Control of the facial muscles
· The muscles of the upper face are innervated
bilaterally, whereas the muscles
of the lower face are controlled by the contra-lateral hemisphere.
· Therefore an UMN lesion – paralyses the lower
muscles on the opposie side.
· LMN lesion – paralyses all facial muscles on
the same side.
UMN
|
LMN
|
· Head injury
· Brain infection
· Tumour
· Haemorrhage/thrombus affecting the arteries
supplying the internal capsule.
|
· Acoustic neuroma
· Bells palsy
· Neurofibroma type 2
· Guillian-Barre syndrome (bilateral)
|
Assessment
· CN assessment.
· Facial Grading System (FGS – Ross, Fradet &
Nedzelski 1996) – Bells palsy.
· Photos/ self-assessment
· Dysarthria/ dysphagia assessment
Synkinesis
· A problem of facial movement control in which
abnormal movements accompany intended voluntary movements.
· Can occur during recovery after facial nerve
injuries.
· If unresolved – can distort facial movements/
expressions and lead to soft tissue contractures + distorted facial resting
posture. Van Swearingen & Brach 2002.
· IN LMN lesions – can occur due to extraneous muscle
movement (over-activity) to
achieve target movements (nerves re-grow thin + with immature myelin sheaths so
new branches can cross innervate).
· Signs = deepened nasolabial fold, retracted
mouth corner, thin/ puffy lips, dipling of the chin.
Management:
|
· Relaxation of facial muscles in a mirror to
achieve symmetry.
· Stretches
· Alignment for activation
· Taping
· Facial exercises.
· Patient education – eye and mouthcare –
prognosis, plan.
|
Facial Rehabilitation:
A Neuromuscular Reeducation, Patient-Centred Approach
Van
Swearingen, J (2008) Facial Plastic Surgery 24(2) 250-258
Previous
Therapy Approaches
·
Concerns have been raised that nonspecific light
massage, electrical stimulation, and repetitions of common facial expressions
are of little benefit.
·
Evidence relating to electrical stimulation have
found that it can be disruptive to
reinnervation and can produce ‘mass action’ – generalised contraction of
many/all facial muscles when patient attempts to produce a specific expression
– it can also reinforce abnormal (synkinetic) patterns of facial activity.
Background
Info
- Functional
facial movements/expressions are usually the result of a combination of facial muscle
contractions, not from isolated movement of one muscle – facial movement
is therefore easily distorted
by changes in facial posture/voluntary movement in any facial region
- Intrinsic
muscle receptors and joint receptors are key in peripheral proprioceptive feedback, however
these are few/absent in the face.
- Facial
movements are under both cortical
and subcortical control. Voluntary movements are typically
cortical, reactional behaviours
(emotional expression) are typically subcortical, facial expression
accompanying purposeful language (e.g. turn-taking cues) are probably
mixture of cortical and subcortical.
- Specific emotions elicit
specific facial movements.
Conversely it is likely that creating a facial movement will
elicit/reinforce a specific emotion. Therapy study found using a stimulus of positive affect
increased responses to therapy for increasing lip corner movement. Other studies have suggested that
impaired smiling is associated with increased psychological dysfunction.
Therapy
Implications
- Lack of proprioceptive feedback in
the face means voluntary attempts to guide facial movement are typically
not accurate unless some form of feedback is provided – e.g. mirror/EMG
is required, if the patient can tolerate looking at self.
- Re:
emotion/facial movement connection –
- Attempts
to elicit specific facial
expressions may be more beneficial than simply aiming at general
movements, due to potential impact on psychosocial well-being
- Use
of emotional stimuli may
support rehabilitation
- Emotional
status may influence the success of facial rehabilitation
Facial
Neuromuscular Reeducation Approach
Basic Principles
- Use
specific, accurate feedback
- Facilitate
facial muscle activity in functional patterns of facial
movement/expression
- Suppress
abnormal muscle activity
- EMG
may be particularly beneficial where there is little or no facial movement
as it provides feedback from very subtle attempts to move/inhibit specific
muscles which may not be visible to the naked eye.
** Studies are restricted to descriptive case reports and small randomised
controlled trials, but these have methodological deficiencies, e.g. lack of
patient-centred outcome measures**
Facial Reeducation: Therapy Guide
Important
Considerations:
- Overcompensation by
the good side can eliminate the need for involvement of the involved side,
resulting in a redefinition of the muscle pattern for a task. This can make the involved muscles
less effective or ineffective because of timing delays, altered position,
and altered length prior to or during the desired action. This can persist because of the
number of times such movements are repeated during the day. Lack of proprioceptive feedback
contributes to this, as the brain does not recognise that an abnormal
pattern of movement is being used.
- In
particular, repeated attempts to get patient to smile can therefore be
counterproductive as the involved side may not be recruited and its
muscles may then become lengthened by constant pulling from the good side
– use centring exercises instead.
Centring
Exercises
These avoid abnormal muscle lengthening whilst enabling involved-side
motor practice.
- Suck
cheeks between your teeth.
- Wrap
your lips over your teeth.
- Sustain
/f/
- Blow
air, as if blowing through straw (better than pucker as its functional
aspect recruits cortical and subcortical control)
- Lip
purse
To elicit a smile/mid-cheek lift.
- Blow
air as if blowing bubbles. At
the same time, try to knit eyebrows together, as if deep in thought.
- Blow
air. Transition to a
sustained /f/. Alternate
between these two.
- Sustain
/f/. At the same try to
‘smile from the corners of your eyes’ (imitates true smile motion
involving eye and facial muscles).
- Blow
air. At the same try to
‘smile from the corners of your eyes’
- Instead of
‘smile from the corners of your eyes’, ask patient to think of a happy
event which can elicit the positive affect marker.
Independent Practice
Only give exercises that the patient can perform accurately, or, where
the patient demonstrates awareness of accurate/inaccurate performance and can
self-correct performance. Advise 5-10
repetitions of 3-5 exercises to be completed twice daily.
Synkinesis
- The
involuntary movement of a facial area associated with an intended facial
movement.
- Examples:
- Eye
closure with smile
- Retraction
of mouth corner and deepening of cheek fold when raising the brow
Treatment-based Classification/Diagnosis
- Four
categories: initiation, facilitation, movement control, relaxation
Initiation
Identifying Features:
- Moderate
to marked asymmetry of face at rest (drooped face, including lower eyelid,
depressed cheek, drooped lower mouth corner)
- Marked
asymmetry with voluntary movement/expressions (i.e. little or no ability
to initiate movement on involved side) with no synkinesis.
Treatments:
- Educate
patient about usual process of recovery/rehabilitation & expected
signs of recovery.
- Active,
assisted range of motion exercises and small
range movement practice – avoid overpowering by the good side. Aim for symmetry where good side
matches weaker side.
Facilitation
Identifying Features:
- Mild
to moderate facial asymmetry at rest (slight lower eyelid droop, slight
flattening of cheek fold, minimal droop of corner of mouth)
- Ability
to initiate facial muscle activity
- Mild
to moderate asymmetry during movement with no/little synkinesis.
Treatments:
- Active
and resistive exercises to increase facial movement.
- Emphasise
importance of accurate movements over quantity.
- Monitor
for development of synkinesis as movements increase – educate pts about
this.
Movement
Control
Identifying Features:
- Asymmetry
typically noticeable during movement, but some residual asymmetry may be
noted at rest.
- Asymmetry
at rest is not ‘droop’ but tightening & retraction of face.
- Synkinesis
is present.
Treatments:
- Teach
pts to isolate muscle contractions and reduce abnormal patterns of
movement – mirror or EMG feedback is essential.
- Consider
reducing movement exercises to small range – where synkinesis is not yet
activated and gradually increase amplitude of movements.
- It
may be effective to allow minimal synkinesis when increasing movement
size.
- As
pts improve they may move into facilitation category.
- Stretching
of muscles may be appropriate where muscle have been shortened due to
abnormal movement patterns or facial guarding (not moving face in order to
avoid showing asymmetry).
Relaxation
Identifying Features:
- Marked
asymmetry of facial posture at rest (tightening or retraction not ‘droop’)
- Spontaneous
twitching and facial muscle spasms.
These often increase with increased effort/movement.
Treatments:
- Progressive
relaxation
- Use
of small, rhythmic, alternating facial movements to relax muscles.
- Sustained
stretching & cross-friction massage to reduce passive tissue
restrictions.
Outcomes
- The sunnybrook facial grading system can be used as an outcome measure