Consultant physician and neurologist, Shamsideen Ogun, discusses the causes, symptoms, and treatment of Bell’s palsy with EMMANUEL OJO.
What is Bell’s palsy?
Bell’s palsy (paralysis) is also called idiopathic seventh cranial nerve palsy. When we say idiopathic, it means that the cause may not be well known. When we say cranial nerves, they are nerves that supply the part of the cranium. There are 12 of them (cranial nerves) but this one is the seventh (cranial) nerve and it’s the one that supplies the muscles of facial expression. So, when we say Bell’s palsy, it is the seventh cranial nerve palsy, and strongly, the seventh cranial nerve has some peculiarities. However, you need to now classify if it’s an upper motor neuron lesion (damage caused by injury or disease) or a lower motor neuron lesion and that’s complicated anyway, but the typical bell’s palsy is the lower motor neuron palsy and it will affect both upper part of the face and lower part of the face, so, there will be some facial asymmetry.
When people have a stroke, they also have facial asymmetry. You have seen some people with stroke as well and you’ve seen that the angle of the mouth deviates to one side but that one is not Bell’s palsy, which seems to cause more of an upper motor neuron type of seventh cranial nerve palsy. In a typical Bell’s palsy which is lower motor neuron, both the upper and lower half of the face will be affected, not only that, the angle of the mouth will deviate completely to one side and they won’t be able to close the eyes, so, the eyes will be open as well. Basically, they have facial asymmetry. I’m giving this explanation because people mistake Bell’s palsy for a stroke and when I tell my students, I let them know that it is very wrong. Bell’s palsy is by no means a stroke at all and I think this is one of the basic education that the masses need to know. Bell’s palsy is not a partial stroke, it is not a mild stroke, it is not a stroke by any means or for any reason.
How can one then differentiate between the two?
Bell’s palsy is a motor neuron lesion, so, both the upper part of the face and lower part of the face will be affected. So, there will be drooping of the mouth and deviation of the angle of the mouth, people with Bell’s palsy won’t be able to close their eyes, most strokes will cause upper motor neuron lesions and that will only affect the lower half of the face. The upper part of the face will be spared, so, that’s number one. One other thing we need to say is that, when we talk about a stroke, it must be vascular. It must be because of blood flow, either because the pipe is blocked or something, but Bell’s palsy has nothing to do with blood flow.
What causes Bell’s palsy?
It is common due to a virus affecting the seventh nerve that passes through a canal. It’s a bony canal and when you have such a virus causing inflammation of the nerve, the nerve will swell and because it’s in a bony structure, it will get compressed and that is why in some very minor cases, we need to do decompression, which is a very minor surgery and that’s very uncommon. So, Bell’s palsy is always a viral infection, whereas a stroke is vascular, resulting from issues of blood flow. Also, this might also sound technical, but a stroke affects some structures we call neural tube structures and there are some structures we call neural crest structures. It’s like having a structure and the inner of it is a neural tube and the outer of it is the neural crest. Neural tube structures are all part of the nervous system.
Neural tube structures comprise three components: the brain, the spinal cord, and the retina of the eyes. So, when we talk about a stroke affecting only neural tube structures, we are talking about the brain, the spinal cord, and the retina (the back of the eyes). Bell’s palsy does not come into any of those three; it is from the neural crest. So, anatomically or structurally, they are not the same in any way. Then more importantly, when we carry out public health education on a stroke, that comes from the symptoms. We use the acronym, BEFAST, which means balance loss, eye vision loss, facial asymmetry (which is the only one that relates to a stroke), arm weakness, speech difficulty, and time. Time is the brain. I will say in the brain, there are 200 billion neurons. Every minute you waste, you are losing 200 million neurons, which is about 12 kilometres of fibre length.
Do some predisposing factors overlap?
Some of them may have sugar issues, that is diabetes, and some have blood pressure issues. In pregnancy as well, you can see some and some with obesity – very obese people and some people with an infection like upper respiratory tract infection. We have a common cold, for instance, that could extend to the seventh cranial nerve and could make it swell, and then in that canal, what we call the facial canal, which is a bony canal.
So, those are the keys to it. Talking from experience now, another thing we can notice about Bell’s palsy is the fact that when people sit in the car or sit close to a fan or a window and the wind blows to them directly, some of them could come down with the disorder as well. That is one of the things which we have observed from clinical and tactical experience.
What are the symptoms of Bell’s palsy?
As I mentioned, the eyes do not close, so, even when there is dust, people with the disorder can’t close their eyes. So, they have some kind of eye irritation as well as some eye discharges and other things that could come up, and as the angle of the mouth deviates to one side, they cannot whistle. If you ask them to, air would escape at the angle of the mouth. So, they puff out their cheeks even though that (whistling) is something they used to do. Also, because this seventh cranial nerve is also close to the eighth cranial nerve which we use for hearing, some people may have an accompaniment of what we call eighth nerve palsy or tinnitus. There will be some ringing sensation in the ears, and some of them may have discharge from the ears, like having pus coming from the ears, what we call otitis media, which means, some inflammation of the middle part of the ear and you have pus coming out.
Does it cause the growth of tumours?
There is also a kind of a brain tumour. It affects what we call the cerebellopontine angle, that’s in between the cerebellum and then the pons, and at that angle, there is what we call an acoustic neuroma. As I said, the seventh, eighth, and sixth cranial nerves are close to each other. If you have such a tumour at that site, like what you call acoustic neuroma, it’s an eighth nerve tumour and we have the pressing on the seventh. One can have some arteries close to the seventh cranial nerve, and those arteries, because they are pipe balloons like the ropes which you have in the tyres of vehicles. When you have such ballooning, they can press on the seventh cranial nerve.
There is a particular artery that is very close to it. It is called the anterior inferior cerebellar artery. So, that artery, when it balloons out, can press on the seventh cranial nerve. In some cases, the patient will, therefore, seminate surgery. It’s very uncommon though. Secondly, if you have a case of an artery that is ballooning out and pressing on the seventh cranial nerve, you may need to do a micro surgery on that vessel that is pressing on it. We do that sometimes as well but most times, we manage them medically and it tends to resolve almost spontaneously in a significant percentage of it, almost up to 90 per cent of them will have a full recovery and of course, anything involving the nerve is not like malaria that will go in three days. It may take up to six weeks to six months for optimal recovery, so, while taking medications, they also need to undergo physiotherapy, to try to take care of the facial asymmetry.
How common is Bell’s palsy?
It’s about one to two per cent common. It’s not that high, though, when HIV came, we were seeing quite a number. We could see some patients with HIV that would have that kind of patient-nerve palsy in the background as well but the frequency is not that high.
What are the complications that come with this condition?
Well, for the complications, most of them will recover but for some that will not recover, they will lose their beauty because the face will shape to one side, looking at the angle of the mouth, when they talk. The lips would be twisted and they cannot whistle. Some of them get infected as well. They get this ringing sensation called tinnitus in the ear. Some will also have headaches, especially if it’s because of a tumour in the brain.
How do you diagnose the condition in the clinic?
It’s usually a clinical diagnosis. When you tell them to show the teeth, you will see the angle of the mouth moving to one side. If you ask them to close their eyes, they cannot, then when you tell them to look up, you will see furrows, we call it furrowing, like when you wrinkle your face. If you look up, you will see the wrinkle on one side of the face. You won’t see it on the side which is affected. They cannot close their eyes, then, the angle of the mouth is deviated to one side. If you tell them to show the teeth, it will be very obvious. You tell them to blow the cheeks, that part of the cheeks cannot blow out because air will escape at the corner of the mouth, then they cannot whistle as well. Then, of course, if you think that there are other areas affected, they may have some problems with hearing, ringing sensation, and then the eyes may look in one direction or the other side.
The other thing that can be done apart from this clinical diagnosis is what we call electromyography and nerve conduction studies. I do EMG and nerve conduction studies and we are very few in the country doing it. So, you can assess those muscles that are mentioned and then do the nerve conduction studies, to test the nerves as well as the muscles they supply and then you do the viral screening for other viruses – HIV, CMV, herpes simplex, herpes zoster. In fact, with herpes zoster, there is what we call Ramsay Hunt Syndrome. In such a case, if you look at the ear lobes, you will see some rashes there, as well in the face of all these we have mentioned.
How is it treated?
Some of the things we do is to give them steroids, about two to four weeks. Steroids reduce the pressure on them, and then give them some neuro-vitamins as well to assist the nerve to regrow or what we call myelination, which is the recovery of the nerve.
It is a treatable condition but I always draw this line. There is a difference between curable and treatable. For curable, if you take your medications you are cured, say malaria for instance, and tuberculosis; when you take your medication, you are cured. The same applies to typhoid too but when you say treatable, some conditions are treatable, not curable. Hypertension, for instance, is treatable and not curable in most cases. So, you have to take your medication.
When I mentioned that you need to give them steroids, different types of steroids assist the covering of the nerves to grow. But we can liken the nerve to electrical cables that you can see. You know, on the inside of electrical cables is brownish copper. So, they have something like an insulator, which is like leather that covers it, the same way the nerves are. The copper there is called the axon, and the covering which is the insulator is the myelin sheath. So, in some cases, it’s just the covering that is affected. Just like electric cables, if the leather has worn out or worn off and you touch the copper inside, it will cause electric shock, so, in that kind of situation, what you do is to find another leather or an insulator around that place. In the same way, some medications can assist work on the insulator. We call them remyelination. Then, of course, they administer things like neuro vitamins too, and then, physiotherapy as well.
What’s the worst-case scenario with Bell’s palsy?
The worst that could happen is certainly not death. I mean, you can’t die from Bell’s palsy. The worst is to have the recovery but there will be an issue of not being able to close their eyes, not being able to wrinkle their face, whistle, blow their cheeks and their mouth deviating to one side. So they could feel embarrassed to talk in public and when they look at the person’s face, it will be observed that there is a facial asymmetry. For most of them, when they try to address the public, they will think the audience stares at their mouths.