Botox: a treatment for facial palsy

Botulinum Toxin, or “Botox”,  is a muscle-relaxing medication that is made from a bacteria called Clostridium Botulinum.  In large quantities, it can be poisonous but when used in tiny dilute doses it has many useful functions.  Botox® and Dysport® are the trade names for Botulinum toxin, produced by Clostridium botulinum.

Several types of toxins have been identified, but Botulinum Toxin type A (BTX-A), is the most potent. BTX-A acts by blocking acetylcholine, a chemical that is responsible for transmitting electrical signals that cause muscle contraction.

The aim is to temporarily weaken or paralyse the injected muscles. Most people are aware of its use as a cosmetic treatment to help reduce facial wrinkles and give muscles a smoother, younger appearance.  However, Botulinum Toxin has been used by the medical profession since 1978, not as a cosmetic product, but for the treatment of many disorders, for example:

  • Migraine headaches
  • Muscle disorders of the neck when they over contract or shorten (Cervical dystonia)
  • Blinking you can’t control (Blepharospasm)
  • Multiple Sclerosis
  • Bruxism (Teeth grinding)
  • Spasticity of the limbs in children with Cerebral palsy

How it helps

Research shows that careful use BTX-A is a successful treatment for the management of facial synkinesis.  BTX-A injections are helpful in restoring facial symmetry at rest and during movement in people who develop synkinesis. It may also be given to people on the unaffected side of their face to inhibit dominance of the unaffected side and improve symmetry of movement.  Research shows Botulinum toxin injections, when given in combination with physical therapy, can be particularly helpful.

What to expect 

In the treatment of facial palsy, BTX-A injections are given through a tiny syringe with a very delicate needle. The amount is very small and often is not as much as a teardrop of fluid. Injections can be painless or may have a slight sting.  Creams that anaesthetise the skin can be used prior to treatment.  It takes up to two weeks for the full effect of the treatment to peak.  It remains active in the muscle for approximately 3 – 5 months depending on each individual person’s response and gradually fades in its effectiveness.

BTX-A should only be administered by clinicians who are experienced in the management of facial palsy, as careful observation of synkinetic movement and assessment of muscle tone is crucial to estimating the appropriate dosage, ensuring a successful outcome and avoiding the side effects of overdosing.

Treating synkinesis and facial asymmetry at rest

Synkinesis is the development of unwanted movement patterns when recovery from facial palsy is delayed or prolonged.  It can occur during facial expressions or when eating, drinking or even blinking.  Synkinetic muscles are constantly working when they should be relaxed and therefore become thickened and contracted leading to poor mobility.  Injecting synkinetic muscles with BTX-A can soften and loosen the muscles which can create better facial symmetry especially at rest.  The cheek muscles commonly become thick and bulky, as well as painful and tender to touch.  Instead of the affected side drooping, as in the flaccid stage of recovery, during the synkinetic stage it lifts up even when the person is relaxed.  Injections of BTX-A into the fold of the cheek can soften the muscles and create better resting symmetry and a more relaxed appearance.  Facial pain may also disappear or lessen after treatment.

Typical synkinetic movement patterns on the affected side are:

  • Narrowing or closing of the eye when the person tries to smile, whistle, pucker, blow, eat, drink or yawn.
  • Raising of the forehead (synkinesis) and/or lifting of the cheek (synkinesis) when the person tries to close their eyes.
  • Tightening (synkinesis) of the platysma (neck) muscle and depressor muscles of the lower face when the person tries to smile, whistle, pucker and/or when eating, drinking and talking.
  • Synkinesis of the frown muscle when the person tries to smile, whistle and/or pucker.

BTX-A can also be a useful way of inhibiting the second problem associated with synkinesis called anchoring.  Facial muscles are attached to each other so synkinetic muscles can inhibit movement of other muscles by anchoring or tethering them.  For example, when a person with synkinesis tries to smile, the recovering but weak smile muscles that lift the corner of the mouth upwards (levator muscles), can become anchored or tethered by the stronger synkinetic muscle that pulls the corner of the mouth downwards (depressor muscles).

The levator muscles in the cheek (Zygomaticus muscles)

The depressor muscles in the lower face and neck

The result is a tug of war between the levator and depressor muscles when the person tries to smile.  The corner of the mouth cannot lift upwards because it is being tethered by the stronger, synkinetic depressor muscles which pull the corner of the mouth downwards.  It may therefore be appropriate to inject the synkinetic depressor muscles with BTX-A.  The depressor muscles will relax, as the nerve signals will be blocked.  This will release the downward pull at the corner of the mouth and allow the levator muscles to lift the corner of the mouth up when smiling.

Careful injections of BTX-A around the eye can inhibit synkinetic movement associated with smiling etc.  It allows the eye to open, relieving feelings of muscle tightness and pain, and improve symmetry of the eyes at rest.

Is it suitable for everybody?

No.  There are certain circumstances in which BTX-A is contraindicated (not allowed).  For example, injections with BTX-A should be avoided:

  • During pregnancy and whilst breastfeeding
  • In people with bleeding disorders
  • In people with infection or inflammation around the proposed injection site
  • People with a certain muscular disorder, for example, Myasthenia Gravis
  • BTX-A injections around the eye should be considered with great caution or avoided if eye closure is incomplete or if there are problems with blinking.  BTX-A will open up the eye and make eye closure and blinking harder to achieve.
  • BTX-A injections around the eye should be avoided in people who have underlying problems with eye health.  If you are under the care of an ophthalmologist, it is important to seek advice before proceeding with BTX-A treatment.

Are there any side effects?

There are very few side effects and injection of BTX-A is a minimally invasive treatment.  BTX-A is a tried and tested medication used safely by the medical profession for over forty years.  However, minor side effects can be experienced:

  • Minor bleeding or bruising around the injection site
  • Treatment around the eye may cause dryness of the eye due to incomplete blink.  This can be easily managed by using eye lubrication.  Symptoms commonly reduce as the potency of the BTX-A diminishes.
  • If the injected dose is too high, then the muscle may become temporarily paralysed or over weakened.  This reduces as the potency of the BTX-A diminishes.
  • Rarely reported symptoms are flu-like illnesses which may develop a day or two after treatment.  This should be reported to the injecting clinician as soon as possible.
  • Very occasionally allergic responses are reported, for example, swelling of the injection site or a rash over the body.  These should be reported to the injecting clinician as soon as possible.  It may mean that you need a different preparation.

Calculating the dose is not a precise science, as people respond differently to different doses.  Erring on the side of caution and gradually increasing the dose to achieve the desired results is the optimum approach.

Treatment and facial rehabilitation

  • The effects of BTX-A wear off after several months and treatment needs to be repeated two or three times/year.
  • Gaining a more lasting effect from this treatment is possible if used in combination with a rehabilitation programme.
  • Whilst the injections are working you have a window of opportunity to make more permanent changes to muscle health.
  • It is difficult to lengthen shortened muscles, but a daily programme of muscle releases and relaxation will help you achieve your goals.
  • However, gaining permanent length and suppleness to the affected muscles will be more achievable whilst the BTX-A is working.
  • Lengthening a relaxed muscle is easier and less painful than trying to lengthen a shortened, stiff muscle.
  • Importantly when the treatment wears off, if you have been diligent with your muscle releases, you will find that you have made a lasting improvement to your facial symmetry, at rest and during movement.
  • Working on inhibiting synkinesis whilst the BTX-A is working will lay down a new blueprint for muscle movement.  Short, regular practice of movement exercises which aim to inhibit synkinesis may have a lasting effect long after the BTX-A has worn off.

There is a tendency for people to stop following their rehabilitation programme after BTX-A treatment because their face looks more symmetrical and feels so much better.  Unfortunately, this just builds a dependency on BTX-A when the aim is to wean yourself from treatment as you achieve your potential for recovery.

Please note: Optimum results from BTX-A injections can only be achieved by adhering to your rehabilitation programme.

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