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Can Botox cause Bell's palsy?

Debunking the myths associated with Botulinum Toxin Type-A


Can Botox cause Bell's Palsy?


It's amazing the amount of misinformation you can find online, which is particularly true when it comes to the medical world, but even more so when you talk about facial aesthetics and the use of Botox and facial fillers for cosmetic purposes. The amount of 'fake news' out there is alarming, particularly when it comes to cosmetic treatments and medical conditions, so when considering treatment options such as Botulinum Toxin Type A (“Botox”) injections and dermal fillers for the first time, it's important to do you research and analyse the data.




What is Botox?


As we age, dynamic wrinkles progress into static lines, and fine lines and wrinkles appear across different areas of our face. Botulinum Toxin Type A ("Botox") is a popular injectable cosmetic treatment which temporarily relaxes the muscles responsible.




When administered by a skilled professional, the prescription medicine 'Botox' is a safe aesthetic procedure. The Botox is administered by tiny needles to specific muscles of the face, with minimal discomfort and virtually zero downtime. The aim of Botox treatment is to only targets the muscles responsible for dynamic wrinkles, not to stop all facial expression, which allows facial movement in a natural way.


Botox, which is a bacterial protein produced by the bacterium Clostridium Botulinum, has been used routinely for many years for medical purposes - but when it comes to its cosmetic use, there are a lot of popular myths doing the rounds.


A lot of these myths are usually centred around adverse effects or allergic reactions


What is Bell's Palsy?


One such myth is that Botox injections can cause Bell's Palsy. Trust me, people are actually googling this! Thousands of people are asking whether Botox treatments can cause a host of medical conditions, such as paralysis of the facial muscles, including Bell's Palsy - you should see the number of hits it gets on Google!


But there is little evidence to suggest that this is the case, but first of all;


What exactly IS a palsy?



Palsy is actually an archaic word for Paralysis. These days, however, it is retained in compound medical terms such as; Bell's Palsy, Cerebral Palsy and Todd's Palsy.


Therefore, a palsy is a medical term which refers to various types of paralysis (loss of movement) or paresis (muscle weakness)






So a facial nerve palsy is the paralysis, or 'inability to move' the muscles on one side of the face that are supplied by a particular branch of the facial nerve.


The name Bell's Palsy comes from the 19th Century Scottish anatomist and surgeon Sir Charles Bell, who discovered that severing the seventh cranial nerve (CNVII or facial nerve) causes facial paralysis.



The facial nerves particular function is to supply the ‘muscles of facial expression’ which is where its name is derived




Unlike other neurological disorders, such as Cerebral Palsy (caused by a problem with the brain) and Todd's Palsy (attributable to epileptic seizures), there is NO identifiable cause for Bell's Palsy.

It is also known as 'Acute Peripheral Facial Palsy of Unknown Cause'.





Bell's Palsy, which represents a dysfunction of the cranial nerve, can occur at any age and is believed to be the result of swelling and inflammation around the facial nerve centre. It is an idiopathic condition as no specific cause has been established which can have significant impact on an individual’s social interaction






Links have been made with viruses including herpes (the herpes virus), influenza and respiratory tract infections, as well as depleted immune systems, pregnancy and stress. The type of facial paralysis caused by Bell’s palsy is not considered permanent, but in rare, severe cases, it does not disappear. Currently, there is no known cure; however, recovery usually begins two weeks to six months from the onset of the symptoms. Most people with Bell’s palsy recover full facial strength and expression.



What are the symptoms of Bell's Palsy?


Bell's Palsy patients may demonstrate symptoms that include partial or complete paralysis of one side of their face, including the inability to close the affected eyelid (eye closure). The temporary weakness can affect facial animation, and is often accompanied by a drooping of the affected side of the face, including the corner of the mouth which results in involuntary drooling. It affects facial symmetry as well as facial balance


Although Bell’s palsy symptoms might appear similar to symptoms of a stroke, the cause is very different. Bell's is a temporary weakness or paralysis and unlike a stroke, the facial weakness develops GRADUALLY.


A stroke is a medical emergency which, like a heart attack, results from a lack of blood flow to a critical body part. A stroke is caused by a blockage in blood flow to the brain, while a heart attack is caused by a blockage in blood flow to the heart. A stroke results in the sudden onset of weakness, difficulty speaking and may affect eye closure on the affected side.


So why would people think Botox causes Bell’s palsy?


Sometimes, an initial facial weakness can occur after treatment with toxin but this is short lived and entirely reversible.


However, in some cases of neuromodulator injections, if the toxin was administered in the wrong location on one side of your face – or too deeply, a side effect could be that it affects adjacent muscles inadvertently, resulting in facial asymmetry. For example, if the toxin were to affect muscles responsible for smiling, this could cause an asymmetric smile, or droop to one corner of the mouth. It is important to note however, that this complication of toxin treatment is due to the action of the toxin on the muscles, and NOT the facial nerve.


The muscles most at risk from this ‘less-common’ complication are;

Zygomaticus Minor - (elevates the upper lip whilst smiling) which could inadvertently be affected when treating lateral canthal lines, and Levator Labii Superioris Alqeque Nasii (also a lip elevator) which could be affected when treating ‘bunny lines’ or a ‘Gummy’ smile


If either of these muscles were affected when, for example treating the left eye crows feet or a gummy smile, it would give the impression of a left sided facial droop as the left upper lip would not elevate when you smiled


The Depressor Labii Inferioris (which allows you to pull your lower lip down, or to the side) can be affected treating the lower face (e.g. pebble chin, downwards turned mouth or Nefertiti neck lift) which would also result in an asymmetric smile.





Does Botox cause Bell's Palsy?









The quick fire answer is NO, because technically Bell's Palsy has NO known cause, so the question should really be.....





Can botox cause palsy of the facial nerve?









For a causal relationship to be established (that is to say, "Botox causes Bell’s Palsy") the onset of facial palsy would need to be within 5-10 days of treatment with Botox. Anything after this would be deemed as 'coincidental'.






There are only three studies to date (worldwide) that report an incidence of facial nerve palsy following Botulinum Toxin Type A (Botox) However, none of these studies used valid methodology and the results are of statistically poor quality.







One study used an unlicensed toxin, the others stated that the onset of neuropathy was at earliest 6 weeks, and in some cases 11 months after treatment with Botox!





"In light of the long duration of the onset of neuropathy in the studies and the incidence of facial nerve palsy, it is difficult to establish whether Botulinum Toxin played a role in the facial nerve palsy or that the palsy occurred as a coincidence"







Care should always be taken when looking at scientific papers - because their true results can be hidden amongst all of the scientific jargon and numbers.





There is NO causal relationship between Botulinum Toxin Type A (Botox) and facial nerve palsy!







How can Botox not damage nerves?


I hear some of you, "But botox is a TOXIN, it causes Botulism so how can it not damage nerves?


Botulism is a rare and potentially fatal illness caused by a neurotoxin produced by the bacterium Clostridium Botulinum (yes, the same toxin as Botox).


Clever scientists develop, dilute and sterilize botulinum toxins for cosmetic and medical procedures in laboratories - so that they won't cause botulism


However; some drugs are indeed toxic to nerves ("Neurotoxic") and various animal studies have shown that certain drugs, especially when injected intrafascicularly (directly into the nerve) can cause severe nerve damage









To answer your question

Does Botox damage nerves?

- No.


Studies conducted to evaluate the potential for neurotoxicity of Botulinum toxin in rats demonstrated that, even when injected directly INTO the nerve, the toxin does NOT damage it.







What can cause facial palsy?


Trauma is a common cause of facial paralysis, and damage to the facial nerve is the second most common cause


Facial nerve palsy or hemifacial spasm can occur after traumatic facial injuries near the facial nerve centre, and the palsy is acute, that is, within 72 hours of insult.



Blunt force trauma, surgical procedures such as reconstructive surgery, or from an injection itself can in fact injure a nerve, but this is not isolated to botox injections - Any injection can, for example dental injections and immunisations.


- But this is usually minor, temporary, and improves within a just a few days.


Nerve trauma due to Botox injections however is HIGHLY unlikely owing the the very small needle being used and the injections themselves are very superficial.


Other causes of facial palsy or facial synkinesis include conditions resulting in swelling of the facial nerve or facial nerve centre, such as Ramsay hunt syndrome (Herpes Zoster Oticus) which occurs when a shingles outbreak affectrs the faical nerve near one of your ears, or certain brain tumours such as acoustic neuroma. Severe cases of Lyme disease can also cause a form of facial paralysis





Botox can help people with Bell's Palsy



Believe it or not – not only is Botulinum Toxin one of the treatment options for Bell’s palsy patients, Botox treatment is THE most effective treatment for someone with Bell’s palsy!



Botox has been around for years to treat medical conditions such as overactive bladders, migraine, cervical dystonia (a neurological movement disorder), chronic migraines and strabismus (also known as 'cross eyed') - Did you know that the ‘anti-wrinkle’ effect was actually a side effect and was a coincidental finding?


In fact, it is one of the most effective treatments for people with Bell’s palsy, and the best approach treatment of partial facial paralysis and synkinesis (involuntary muscle spasms)



One of the desirable characteristics of Botox is a minimal effect at short distances from the injection site; so it is ideal for medical reasons and can actually be used to treat Bell’s palsy – i.e. to treat the UNAFFECTED side.


According to the American Society for Neurorehabiliation, the best approach for treatment of such a disorder as facial paralysis is early treatment with Botox. Botox is one of the most effective treatments for partial facial paralysis and has been a mainstay treatment for these patients for the past two decades.


It relaxes unwanted muscle movements on the normal side of the face and reduces tension in areas of the face that are hyperactive due to involuntary facial movements which can occur in the aftermath of Bell’s palsy.


In protracted cases of Bell’s palsy, or those unable to generate an appropriate smile due to partial facial paralysis or synkinesis of the affected side, best results can be obtained with physical therapy and occupational therapy. In rare cases of permanent facial nerve paralysis (and partial facial paralysis) surgical treatments aimed at regenerating nerve fibres are available, such as ‘selective neurolysis’ (also referred to as modified selective neurectomy) as well as a nerve graft, whereby paralyzed facial muscles are connected to healthy nerve tissue to restore movement.


So remember, always question what you hear! There are a lot of myths out there regarding Botulinum Toxin, and I aim to debunk them – one myth at a time!


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Comprehensive debunk!

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