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Facial nerve damage: Causes and symptoms

 Facial nerve damage: Causes and symptoms

You have nerves in every part of your body that send signals to and from your brain via your nervous system, helping you to move your muscles and allowing you to feel sensations – to name just two of their functions. The main nerve in your face is called the facial nerve – or, in medical terms, cranial nerve VII (the seventh cranial nerve).


What is the facial nerve?

Your facial nerve helps you to move your facial muscles, allowing you to produce facial expressions, as well as other things like helping you to taste your food by sending information about taste from your tongue to your brain and stimulating your lacrimal gland to produce tears. Your facial nerve has an impact on your hearing too as it controls muscles in your inner ear (the stapedius muscles), which moderate your sensitivity to the loudness of sounds. It also helps you to swallow by stimulating the stylohyoid muscle, plus  it’s involved when you move your jaw.
 

Where does the facial nerve enter and exit the skull?


The seventh and one of the longest of 12 cranial nerves, your facial nerve is actually two nerves, with one found on each side of your head. It starts in your brainstem (the part at the bottom of your brain that looks like a stalk) and travels up through the base of your skull, where it passes close by the eighth cranial nerve (vesibulocochlear nerve), the nerve that’s involved in hearing and balance.
 
Each of the two facial nerves leave the skull and enter your face on either side through an opening in the bone near the base of each ear called the stylomastoid foramen. At this point it enters the parotid gland, where it divides into five main branches, each of which connects with different muscle groups that control facial expression.
 

What are the five branches of the facial nerve?


The five branches of the facial nerve and the muscles controlled by them are:
 

  1. Frontal or temporal branch: this controls the frontalis and obicularis occuli muscles, which are muscles found in the upper portion of the face (the muscles in your forehead, for example).

  2. Zygomatic branch: this controls the muscles that allow you to close your eyes.

  3. Buccal branch: the muscles controlled by the buccal branch include those involved in moving your cheeks (including the buccinator muscle). They also include muscles that control your nose and nostrils, the corners of your mouth (helping you to smile) and your upper lip.

  4. Marginal mandibular branch: the muscles in your lower lips and face, including those that are involved in making you frown, are controlled by this branch.

  5. Cervical branch: this branch of the facial nerve controls the muscles in your chin as well as the platysma muscle, which is in your neck.

 

What are the 12 cranial nerves?


While the facial nerve is the main nerve in your face, other nerves affect your face too, including one you may have heard of called cranial nerve V – more commonly known as the trigeminal nerve. The largest of the cranial nerves, this extends from your brain into branches that travel throughout your face, its main purpose being to help you to feel sensations in your face and scalp as well as control the muscles that help you bite, chew and swallow.
 
As well as those already mentioned, the other cranial nerves have an impact on your face, neck, head and/or scalp too, and include:
 
Olfactory nerve (cranial nerve I) – this is involved in how you smell things.
 
Optic nerve (II) – this is the nerve that involves vision, sending information about the light entering your eye to the brain.
 
Oculomotor nerve (III) – this controls the muscles around your eyes and the expansion and contraction of the pupil.
 
Trochlear nerve (IV) – this controls your superior oblique muscle, which controls your eye movements.
 
Abducens nerve (VI) – this is another nerve that controls a muscle associated with eye movement, namely the lateral rectus muscle.
 
Glossopharygeal nerve (IX) - this nerve extends into the neck and throat area, helping the back part of your tongue to have a sense of taste and stimulating a muscle in the back of the throat called the stylopharyngeus muscle.
 
Vagus nerve (X) – this is the longest of the cranial nerves, extending from your head right down to your abdomen. It controls muscles in your throat and allows the root of your tongue to taste.
 
Accessory nerve (XI) – this nerve controls the muscles in your neck.
 
Hypoglossal nerve (XII) – moving your tongue involves this nerve, which travels from the brain stem to the jaw.
 

Types of facial nerve damage 


There are several conditions that can injure, damage or weaken the facial nerve, causing facial nerve paralysis. This can cause symptoms such as facial twitching, a lopsided appearance, problems with eating and drinking, a drooping eyebrow, loss of smell or taste, problems with blinking or closing your eyes and an inability to move some of the muscles in your face.
 
The main conditions that affect the facial nerves include:
 

Bell’s palsy


Thought to be sometimes triggered by a viral infection – the herpes simplex virus that causes cold sores and the varicella-zoster virus that causes chickenpox are the two main contenders – Bell’s palsy affects around one in 60 people at some time or other, usually between the ages of 15 and 60 years (i). It happens when inflammation surrounds the facial nerve as it passes through the skull, which stops the facial nerve working properly.
 
Symptoms of Bell’s palsy include facial drooping to one side, including a lopsided smile, chewing problems, not being able to move your forehead, cheek, eyelid or lip muscles on one side, and certain speech difficulties. Pain isn’t usually a symptom, though some people may experience a mild ache or pain near the ear. Loss of taste on the side of the tongue that’s affected may also happen, and you may also hear things more loudly than usual, with loud sounds causing discomfort. Bell’s palsy doesn’t affect any other part of the body.
 
The good news is that most people who develop Bell’s palsy recover in full, especially those who are treated for it, with the majority regaining function of the facial nerve within a couple of weeks (though it may take up to nine months to recover fully).

 

Ramsay Hunt syndrome


Facial weakness or drooping, loss of taste and pain are also among the symptoms of Ramsay Hunt syndrome, a condition caused when the varicella-zoster virus is reactivated and affects the facial nerve. 
 
The varicella-zoster virus causes chickenpox, most often in children. But after the initial symptoms subside the virus travels up a nerve root and stays dormant. However, it can be reactivated later in life, causing shingles. If the virus becomes reactivated in part of the facial nerve, it can also cause the symptoms of Ramsay Hunt syndrome.
 
The risk of developing shingles increases with age, with experts calculating that half of cases are found in those who are aged 60 or older. Facial nerve problems, however, are thought to only happen in around one percent of those who have shingles, mostly women aged between 50 - 60 years old (ii). 
 

Lyme disease


An infection triggered by a bite from an infected tick, Lyme disease causes a range of symptoms, one of which can be facial muscle weakness and paralysis caused by inflammation of the facial nerve. Typically this can cause one side of your face to droop. We don’t know how many people are affected exactly, but Public Health England estimates there are up to 3,000 confirmed cases of Lyme disease every year in England and Wales (iii).
 

Stroke


Muscle weakness, often on one side of the body, is one of the best-known symptoms of a stroke. The muscles affected often include the facial muscles – though according to the charity Facial Palsy, facial paralysis in stroke cases happens because of damage to the facial nerve inside the brain rather than damage to a part of the nerve in the face itself (iv). This damage often causes weakness of the muscles in the lower part of one side of the face, causing drooping and, if the corner of the mouth is affected, drooling.
 

Guillain-Barré syndrome


A rare condition that affects the nerves, Guillain-Barré syndrome mainly affects the feet, hands and limbs and causes numbness, weakness and pain. It can, however, also affect the facial nerve, causing facial weakness on one or both sides of the face and leading to problems with eye movements, swallowing, chewing and speaking.
 

Sarcoidosis


Numbness or weakness of the face, including that also of the arms and legs, can be a symptom of a condition called sarcoidosis. Around one in every 10,000 people in the UK is thought to be affected by sarcoidosis (v), a condition where lumps called granulomas develop in parts of the body including the nervous system, heart, lungs, lymph glands, skin, joints and eyes. Around one in 20 people with sarcoidosis develop problems with their nerves and nervous system (v).
 
Meanwhile, facial nerve problems can be caused by head or facial injuries – considered one of the most common causes of severe permanent facial paralysis (vi) – as well as peripheral neuropathy (damage to nerves in your hands, arms, feet and legs), ear infections and tumours. One of the most widely known problems caused by one of the other cranial nerves is trigeminal neuralgia, which is a disorder of the trigeminal nerve that causes sudden, severe facial pain (for more information read our guide to trigeminal neuralgia).
 

What are the symptoms of facial nerve damage?


See your GP if you develop any of the following symptoms on a temporary or permanent basis, as you may have developed a facial nerve problem:
 

  • Speech problems (such as uncleared or slurred speech)

  • Problems with eating or drinking (for instance food falling out of your mouth or drooling)

  • Drooping or lopsided face, twitching facial muscles

  • Problems with blinking or closing an eye

  • Hearing sounds more loudly on one side 

  • Loss of taste and/or sell

 

Can facial nerve damage be treated?


If your doctor suspects you have a problem with your facial nerve they may refer you to a hospital specialist, often a neurologist, for a diagnosis. Some of the tests you may need include nerve conduction tests, scans, x-rays and electromyography (nerve conduction tests record the electrical conduction of impulses travelling along your nerves, while electromyography involves testing the electrical activity of your muscles).
 
Once your specialist has confirmed you have a facial nerve disorder, you may need one or more treatments, depending on your diagnosis. If you’re diagnosed with Bell’s palsy, for instance, treatment with medication is usually recommended, including a course of steroid tablets to help reduce the inflammation that’s causing the problem with the nerve. Some people with Bell’s palsy cannot close one of their eyelids completely, and will also need eye drops and ointment to keep their eye lubricated.
 
Further treatments, depending on your diagnosis, may also include:

  • Facial and facial nerve surgery

  • Botox injections 

  • Facial exercises/retraining

 

Can you prevent facial nerve problems?


There may not be much you can do to prevent most of the conditions caused by problems with your facial nerve. However, since trauma and injury are among the most common causes of long-term facial nerve problems, protecting your face and head from injury as much as possible is an obvious step you can take to avoid it, especially if you have a job or take part in activities where a head or facial injury is a particular risk.
 
Some cosmetic surgery procedures may also cause damage to the facial nerve, as avoiding the nerve during surgery can sometimes be a challenge. If you’re considering having facial cosmetic surgery, your surgeon should explain the risk to you so that you can make an informed decision on whether or not to go ahead.
 

How to keep your nerves healthy


There’s nothing special you can do to make sure your nerves stay healthy. However, as with other areas of your health, having a healthy lifestyle is the best way of preventing illness, and as such may help keep your nervous system healthy too.
 
Some of the best ways to keep your lifestyle healthy include:

  • Eating a healthy, balanced, nutritious diet that includes at least five portions of fruit and vegetables every day

  • Drinking plenty of fluids – around six to eight glasses or cups a day is usually recommended

  • Taking regular exercise – try to aim for the recommended amount of physical activity, which is 150 minutes of moderate activity each week, and avoiding sitting for long periods

  • Getting plenty of sleep and establishing a regular bedtime routine (for more details read our sleep and insomnia guide)

  • Avoiding smoking and using recreational drugs

  • Drinking alcohol in moderation (aim for a maximum of 14 units a week, spread evenly over at least three to four days)

  • Making time for relaxation

  • Looking after your cognitive health – try brain training games, for instance


Certain nutrients and nutritional supplements may also be helpful, including:
 
B complex   B vitamins help support a healthy nervous system and are available in a wide range of foods including peanuts, oats, bananas, fish, meat, poultry, soya beans, dairy foods, leafy green vegetables, broccoli, kidney beans, chickpeas, peas and fortified breakfast cereals. You can also top up your levels by taking a good-quality B complex supplement.
 
Magnesium   This is important for a range of body functions, including nerve health. For instance magnesium is essential for healthy nerve transmission and neuromuscular conduction, and has been implicated in several neurological disorders (vii). You can find magnesium in foods including spinach, nuts, wholemeal bread, pumpkin seeds, cocoa powder and soya milk, as well as nutritional supplements.
 
Zinc   This mineral is considered essential for the normal development of the nervous system (viii), as well as for communications between nerve cells in your brain. You can find it in foods such as dairy foods, meat, poultry, shellfish, bread, wheatgerm and pumpkin seeds. It’s also available as a nutritional supplement.
 
High-strength fish oils   The omega-3 fatty acids found in oily fish are widely thought to help reduce inflammation, which can be a factor in some types of facial nerve disorders (Bell’s palsy, for instance). Oily fish include salmon, sardines, mackerel and herring, but you can also get a supply of omega-3s by taking a high-strength fish oil supplement. If you’re vegetarian or vegan, you can get the same beneficial omega-3s in a supplement sourced from marine algae instead of fish.
 
Vitamin C   Vitamin C is important for proper nervous system function (ix), and according to experts at St George’s University Hospitals, when it’s taken in doses higher than the usual recommended daily amount (40 - 80mg) it may also help prevent nerve related pain (x). Again, this is found in a variety of foods including citrus fruit, berries, broccoli, red and green peppers and potatoes. But if you think you may be running low and need a vitamin C boost, there are many supplements available in different strengths.
 
Vitamin D   If you want to protect your nerves it may also be a good idea to increase your intake of vitamin D, since vitamin D may help protect the nervous system, reduce inflammation and protect nerve cells from damage. There’s some evidence for instance, that suggest low levels of vitamin D may be linked with inflammation (though it’s not known why) (xi). Yet having a low level of vitamin D is common, particularly in northern hemisphere countries like the UK.
 
Indeed, Public Health England advises adults and children over the age of one year old to consider taking a daily supplement containing 10mcg of vitamin D, particularly during autumn and winter (xii), since that’s when we’re short on sunlight (exposing your skin to sunlight is considered the best way to get vitamin D).
 
However if your skin is rarely exposed to the sun during the spring and summer months – if you spend most of your time indoors, for instance, or if your skin is always covered when you’re out and about – you may need to take vitamin D throughout the year. People with dark skin from African, Afro-Caribbean and South Asian backgrounds should consider taking vitamin D all year round too, PHE advises.

The recommended form of vitamin D is vitamin D3 or cholecalciferol, as it’s the natural form of vitamin D that your skin makes when it’s exposed to sunlight. Vitamin D3 supplements are available in tablet form, and now you can get them in veggie-friendly drops too. However most vitamin D3 supplements are made from the fat of lamb’s wool, which means they’re unsuitable for vegans. The good news is that vegan vitamin D3 supplements sourced from algal are now more widely available.
 
Multivitamin and mineral   Most of the above nutrients are available in multivitamin and mineral supplements, which may be a more convenient way of taking more than one of them singly. Taking a multivitamin and mineral supplement is also handy for making sure you’re getting the essential nutrients your body needs, especially if you don’t always eat as healthily as you should. Look for a supplement with decent amounts of each of the above nutrients to help optimise your nerve health.
 
Want to know more about multivitamins and the amounts of individual nutrients you need each day? Take a look at our guide to multivitamins and mineral requirements.
 

Find out more


If you need information on a wide variety of health conditions, including advice on how your diet and lifestyle can help keep you healthy, visit our pharmacy health library.



References:

  1. Available online: https://patient.info/brain-nerves/bells-palsy

  2. Available online: https://patient.info/doctor/herpes-zoster-oticus-ramsay-hunt-syndrome

  3. Available online: https://cks.nice.org.uk/topics/lyme-disease/background-information/prevalence/

  4. Available online: https://www.facialpalsy.org.uk/inform/about-us/

  5. Available online: https://www.sarcoidosisuk.org/information-hub/about-sarcoidosis/

  6. Available online: https://www.uhs.nhs.uk/departments/brain-spine-and-neuromuscular/the-wessex-facial-nerve-centre/types-of-facial-nerve-disorder

  7. The Role of Magnesium in Neurological Disorders. Nutrients. 2018 Jun;10(6):730. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6024559/

  8. . Zinc in the central nervous system: From molecules to behaviour. Biofactors. 2012 May-Jun; 38(3): 186-193. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3757551/

  9. Does Vitamin C Influence Neurodegenerative Diseases and Psychiatric Disorders? Nutrients. 2017 Jul;9(7):659. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5537779/

  10. Available online: https://www.stgeorges.nhs.uk/wp-content/uploads/2019/01/TRA_VITC_02.pdf

  11. Vitamin D and inflammation in major depressive disorder. J Affect Disord. 2020 Apr 15;267:33-41. Available online: https://www.sciencedirect.com/science/article/abs/pii/S0165032719325595?via%3Dihub

  12. Available online: https://www.gov.uk/government/news/phe-publishes-new-advice-on-vitamin-d

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Our Author - Christine Morgan

Christine

Christine Morgan has been a freelance health and wellbeing journalist for almost 20 years, having written for numerous publications including the Daily Mirror, S Magazine, Top Sante, Healthy, Woman & Home, Zest, Allergy, Healthy Times and Pregnancy & Birth; she has also edited several titles such as Women’ Health, Shine’s Real Health & Beauty and All About Health.

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