Facial Weakness Overview

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