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SA: Hello, and welcome to Master the MRCPCH. In this series, we tap into the expertise here at Great Ormond Street Hospital to give you an overview of a topic on the RCPCH exam curriculum. So whether you're revising for an exam or just brushing up on a need to know topic, hopefully this podcast can give you the information that you need.
I'm Dr. Sarah Ahmed, a paediatric registrar and the current digital learning education fellow here at GOSH.
Today we're going to be talking with Dr. Maria Gogou, Senior Clinical Fellow in Neurology, about intracranial hypertension, covering presentation, causes, investigation, management, and prognosis. This maps to the neurology section of the exam curriculum.
SA: Maria, thank you for coming back on the show today.
MG: Hi, Sarah. Nice to see you again.
SA: So before we delve into more detail, I wanted to start by asking what would you like people to get out of listening to this podcast?
MG: First of all, I would like to help people be aware of the mechanisms of increase in intracranial pressure. Another goal would be to help them familiarize themselves with the diagnostic approach and treatment management of cases of increased intracranial pressure in childhood. And finally I would say that it's important to be confident to put a diagnosis of idiopathic intracranial hypertension and avoid common pitfalls in everyday practice.
SA: Amazing. I'm sure we'll cover all of that in the next half an hour or so.
So let's start really basic. Do you have a definition for what intracranial hypertension is and is it different to raised intracranial pressure?
MG: Actually, raised intracranial pressure is equivalent to intracranial hypertension. First of all, it would be helpful to think what intracranial pressure means. So, it represents the pressure which is exerted on the brain tissue within the scalp by fluids like cerebral spinal fluid, for example. This pressure changes with age. In childhood the normal rate is between 11 and 28 centimetres of water. In younger ages, for example, in infants, it is usually lower, like between three to seven centimetres of water. And this is a really significant parameter uh, because let's think that our brain needs oxygen and glucose for its metabolic needs. And both of them are supplied to the brain via blood flow. The brain function depends on a good cerebral blood flow, which depends on what we call cerebral perfusion pressure. And this pressure of perfusion depends on the balance between the resistance of the various cerebrovascular structures and the difference between the mean arterial pressure and the intracranial pressure. So the higher the arterial pressure is, the better is the blood flow to the brain. On the other hand, the higher the intracranial pressure is, the lower is the cerebral blood flow. So we understand that it's important to look at this parameter and to understand that changes in that can have a significant pathophysiological impact.
So when we say intracranial hypertension in childhood, we usually mean that the level of the pressure is more than 25 centimetres of water, in a child with normal weight and unsedated, or more than 28 centimetres of water in a child who is overweight or obese, perhaps or sedated.
SA: Why does them being sedated make a difference?
MG: Because when someone is sedated they tend to hypoventilate, which leads to an increase in the level of carbon dioxide and this in turn can increase the level of the intracranial pressure. So we are a bit more uh, open to accept one, two of water higher intracranial pressure.
SA: Is intracranial hypertension a common condition? I feel like it's something that we're seeing more and more.
MG: Um, actually, the intracranial hypertension can be either to a specific cause, and this is a case of secondary intracranial hypertension, as we tend to call it. Or we cannot find any cause, any specific underlying cause, so we tend to call it idiopathic intracranial hypertension.
In the case of secondary cases, the real prevalence depends on the underlying condition, because it can be, as we will say, anything from a brain tumour, from uh, intracranial bleeding, and so many other causes.
On the other hand, the, the pure idiopathic intracranial hypertension is quite rare as a condition. So in the United Kingdom, it is estimated that less than one per 100, 000 of children is diagnosed with this condition. And it tends to be more prevalent in children after puberty. It is worth mentioning that in this age group, the rate can be up to twice the rate in younger ages, in prepubertal children. And also the, this group of children I mean, after puberty, they tend to have some similarities with the adults who also present this condition. What I mean is that it is more frequent among females. And also it is more frequent among children and adolescents who have obesity. Whereas the children before puberty, they tend to represent I would say a separate cohort with different features.
SA: Can we talk a little bit more about those causes of secondary intracranial hypertension?
MG: Actually, the list is quite, it's quite big and a number of conditions can lead to increase intracranial pressure. And this is usually done either via an increase in the cerebrospinal fluid, so an increase in production, or a problem with the flow and obstruction, for example. Another big cause is the increase in the brain volume. For instance, after a cytotoxic insult or in the context of brain swelling. So if we think about causes leading to those conditions, we will think about brain tumours. We will think about a cerebrovascular accident, for instance, a rupture of an aneurysm, or intraventricular haemorrhage, for example. We will think of central sinsus venous thrombosis, a traumatic brain injury, we need to think of central nervous system infections like meningitis. We must not forget craniosynostosis as a cause of increased intracranial pressure, as well. We need to have in our mind that the number of immune mediated conditions can lead to increase the intracranial pressure. For example a child with the Mog antibodies positive can have intracranial hypertension as one of the manifestations of the underlying disease. We have many systemic causes for example, systemic lupus erythematosus can be associated with this condition as well. Or uh, Graves has also been described to be a cause of increased intracranial pressure. We need to think of, as I said, other immune mediated conditions like ADEM, for example. Sometimes metabolic dysregulation can be a cause of increased intracranial pressure. For example, cases of severe renal or liver failure or diabetic acidosis or significant hyponatremia. We encounter this condition in children with obstructive sleep apnoea syndrome. Sometimes, occasionally, with developmental structural lesions, for instance, arachnoid cyst. And of course, let’s not forget hydrocephalus as a cause of increased intracranial pressure which can result from trauma, haemorrhage, cancer, and infection. So the list, of course, is quite broad.
SA: It's such a broad list. I don't think I appreciated how broad a list it was.
MG: And I have to add the cases of iatrogenic intracranial pressure. For example, there are medications which can cause this condition. Some antibiotics, like the tetracyclines, which can be used for acne treatment, or vitamin A supplements when they lead to quite high vitamin A levels. Other medications include growth hormone or uh, thyroxine in some cases, and sometimes we can also see increase intracranial pressure after withdrawal of steroids in people who used to be on a long term treatment.
SA: So what are the symptoms that you would expect children to present with if they have intracranial hypertension?
MG: Yes the most frequent clinical presentation is that with headaches. So headaches is the most prominent symptom. The clinical traits of those headaches can vary a lot, to be honest. Very frequently they have what we call a red flag. For example, they can awaken a child from sleep, or a child can wake up with a headache. It is tricky in clinical practice because sometimes they may have features which look like another headache syndrome, for example, migraine. And if we think that migraines are quite frequent in the population, it is not unlikely to be confused, or it's not unlikely a child to have both conditions. I mean, a background of migraines, and then for another reason, develop intracranial hypertension as well. A clinical sign which is quite specific is that those headaches tend to be worse in supine position. So when someone is lying, and they tend to get better when one sits up or, or stands up, actually. Sometimes the headaches can be quite explosive and have a very dramatic onset. Some other times they can be more subtle and more chronic. So we really need to have an open, an open mind. And regarding the pain yes, the expression of the pain is very subjective and depends on the age of the child, both the biological age and the developmental age.
Another common clinical feature is tinnitus, which can accompany the headaches. Very frequently, we can also have visual disturbance. And when I say visual disturbance, I mean, obscuration of the vision, especially in the central, in the central visual fields or sometimes restriction of the whole visual fields.
Other symptoms can include the pains in the back, pains in the neck. Diplopia is another ocular manifestation, which can be seen in clinical practice. We can have dizziness sometimes, or radicular pains in nerves. And I have to say that in, in the younger ages, the symptoms might be more uh, vague, like we can have sleepiness, or irritability, or tension in the baseline function of the child. This is quite significant because theoretically, we would expect intracranial hypertension to be a problem in an older child with closed cranial sutures. So the question which arises sometimes is whether an infant or a young toddler with open sutures can have intracranial hypertension. So in a healthy otherwise child, the answer would be technically no. Nevertheless, in practice, we have encountered a couple of cases which show the opposite. For example, I can recall the case of a baby with hydrocephalus, in the context of congenital hydrocephalus, in the context of a metabolic disease who, who struggled with symptoms of irritability and, and somnolence. And when a lumbar puncture was performed for diagnostic purposes, the symptoms were alleviated. So, this raises some questions whether in fact some degree of increased intracranial pressure was present. So, yeah, it needs some caution in everyday practice.
And sometimes of course it can be another finding. A child visits the eye doctor for a regular check up and they're found to have papilledema. And then this leads to the diagnosis of increase in the cranial pressure.
I also need to add that sometimes we can have a palsy of the sixth cranial nerve in those children or other cranial nerves as well. The sixth cranial nerve is the most common one because if we remember, it has a quite long intracranial course so it's more vulnerable to increases of the intracranial pressure.
SA: You mentioned red flags and headaches, which I suppose can be quite nonspecific, but is there anything else that you'd be looking for when you're taking the history or examining the child?
MG: We need a quite detailed history, a quite detailed physical examination. For example, even examination of the skin for rashes, examination of the joints because it can manifestation of a rheumatological disorder sometimes. So the the examination needs to be really, really full. We need to be careful and look for any neurological deficits, because this can make sometimes a difference between a secondary and the idiopathic case of intracranial hypertension. And this is what happens with the level of consciousness. Any change in the level of consciousness is suggestive of a secondary cause of intracranial hypertension, not idiopathic. I want to highlight that.
And we need a detailed history of the medications or treatments that the child has taken, a detailed history of recent infections that the child might have had. From a clinical examination point of view, it is also significant to measure head circumference in a younger age, and not to forget to measure weight and BMI in older children as this can be a risk factor for an intracranial hypertension. And also not to forget to measure blood pressure as well, because increased intracranial pressure can subsequently lead to systemic hypertension sometimes.
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SA: And you mentioned lumbar puncture and thinking a little bit about that long list of potential secondary causes. What are the investigations that you would do if you suspect someone might have intracranial hypertension?
MG: Neuroimaging is needed first of all. Ideally an MRI of the head. It is also important to exclude central sinus venous thrombosis, this can be done via an MRI, though MRV or CTV may be needed as second line investigations to confirm. If the waiting times are long, then the MRV can be replaced by a CTV which can be done much more easily.
In the MRI, we can find some findings which are very typical for increased intracranial pressure. For example we can have some flattening of the posterior aspect of the globus bilaterally. We can have some enlargement of the optic sheath. We can see a finding of an empty sellar. And those findings are quite strongly point over the direction of increased intracranial pressure.
We need a very good ophthalmological investigation, which, of course, will include examination of the fundi to check for papilledema. It will include the visual acuity, colour vision, eye motility to check for diplopia, which can be a very frequent clinical sign, as I said, and check of visual fields. And whenever this is possible, we can also do what we call OCT, so optical coherence tomography, which can give a better idea of the retina and the visual fields.
And of course, diagnosis is made by lumbar puncture. So I said briefly before that there are aspects which can affect the level of intracranial pressure. Sedation can increase the level. Other situations which can increase the level is a sitting position or a child who is crying or uh, is very irritable. On the other hand, a child who is very stressed and hyperventilates, this can have the opposite effect and reduce the intracranial pressure. To be honest, in cases of severe intracranial hypertension I don't think that those aspects will make a very big difference, but they might be more important in marginal, marginal cases.
So, perform a lumbar puncture in the left lateral decubitus position in a way that it's the most comfortable to the child. We tend to perform it under sedation if the child does not collaborate very well. It is helpful if we avoid to have uh, high levels of carbon dioxide, so more than 45 millimeters, but this might be, not be easy in, in everyday practice. We just need to have it in mind and note the level of the carbon dioxide when the pressure was measured.
We need to be particularly careful when performing LP in a case of secondary intracranial hypertension as there is always the risk of herniation.
And of course, because we need to exclude the number of secondary cases we must perform some other investigations as well in blood. We need to exclude anaemia because anaemia can be a cause of this condition, I didn't mention before. Thyroid function tests, electrolyte profile, calcium levels, PTH levels because hyperparathyroidism can be a cause sometimes as well. Levels of vitamin D and vitamin A. As well as blood tests to, to diagnose or exclude a viral infection because sometimes this can accompany a viral illness like COVID infection, Lyme disease or Epstein Barr viral infection.
SA: And if you've confirmed that diagnosis with your investigations, how do you go about treating these children?
MG: This depends on the cause, of course and the clinical situation of the child. For example, a patient who is acutely unwell in an ICU or being transferred to the hospital via ambulance ICP can be reduced via elevating the head of the bed to thirty degrees, keeping the neck in a neutral position, maintaining a normal body temperature, and preventing volume overload.
For patients with uncontrolled elevation of ICP, there are surgical interventions that neurosurgeons can offer: EVD placement, evacuation of mass lesion and decompressive craniectomy. If we find a brain tumour, this needs to be addressed by neurosurgeons and consider the option of surgery.
In general, we need to treat all underlying conditions. Treat anaemia, for example, if this is supposed to be the cause. Or to consider withdrawing some medication if this is suspected to be the reason for increasing the cranial pressure. And the most important thing in management is to try and protect vision, because this is the most serious complication of intracranial hypertension – the impact on the visual function. So for this reason, first of all, once we have performed a lumbar puncture, this is also a therapeutic measure, because we remove cerebral spinal fluid, and we drop the pressure. And what we usually do in clinical practice is to drop the pressure, either to normal values, like, between 20 and 25 centimetres of water, if the pressure was no higher than 40 centimetres. Or if it was higher than 40, we tend to drop it to the half of that. For example, if it was found to be 58, we tend to drop it to 29/30centimetres in order to avoid, you know, sometimes if there is a significant loss of um, CSF, we can have the opposite, we can have headache from low intracranial pressure. Once again, we need to be careful when reducing pressure in a patient with secondary intracranial pressure, always considering the risk of herniation.
And after that it is important to make sure we protect the vision. So, if that child was found to have papilledema or any other problem, with the vision, we start on some treatment to try to keep the pressure at normal levels.
The most common treatment we start is acetazolamide, which is a carbonic anhydrase inhibitor, and this is quite effective for this condition. Of course, we need to be aware of some side effects of this medication, so it can cause some metabolic acidosis sometimes. Or it can have side effects like sensation disorders or some tingling sensation. Those are the most common ones. If we are concerned about any potential side effects, it is helpful to monitor pH of blood and bicarbonate levels via frequent blood gas tests. And if we have a child with the symptoms from acetazolamide or levels of bicarbonate less than 18, we have the option of starting the bicarbonate supplements as well to, to help them.
Other medications are topiramate, which is also an inhibitor of carbonic anhydrase. Furosemide can be used, but quite less frequently.
When we have a child with a very severe visual problem, because of increased intracranial pressure, and we are concerned about that, and we want to protect the vision, we can start on high doses of steroids, IV methylprednisolone, for a few days to help drop the pressure quickly and protect visual function. And in those cases, there are also neurosurgical approaches like fenestration of the optic nerve but in most cases the baseline management strongly depends on a treatment with acetazolamide.
We need to have in our mind that we need to liaise closely with eye doctors and those children need to be under regular ophthalmology follow up because the course of papilledema and the visual function will depend, will determine how long the treatment will be. And of course, to make sure that we have addressed a number of underlying risk factors, for instance help with weight management in an overweight or obese child, and to make sure that the family is well supported in everyday life.
SA: And thinking more specifically about idiopathic intracranial hypertension, what's the prognosis for these children?
MG: First of all, I need to highlight that it's quite rare as a condition. We tend to over diagnose this condition, to put a label very, very quickly without having done all exhaustive investigations which are needed.
In order to diagnose idiopathic intercranial hypertension, we need to have a normal neurological examination apart from the palsy of the sixth cranial nerve, as I said, and to have completely normal neuroimaging, you know, apart from those findings which can be secondary to the increased pressure itself. And also normal CSF, and I need to highlight that because sometimes, need to underestimate it. For example, I can think that the case of a child who was referred for idiopathic intercranial hypertension, but having a look at his CSF profile, there was an increased number of white blood cells and a marginally elevated protein level. And this child finally was found to have a Mog antibodies positive. And when we repeated his neuroimaging we also found some characteristic signal changes of this condition. So what I want to highlight is that idiopathic intercranial hypertension is the diagnosis of exclusion. And the management is is similar. So we don't have a secondary cause to treat, but we go on and treat with the acetazolamide. And frequent ophthalmology checkups.
Prognosis now. Prognosis is good in general, in this condition. However, sometimes symptoms tend to persist. So it's not unlikely, one or two years after the initial presentation, to have children who still have headaches. They, they will be better and less frequent than in the beginning, but they might still be present. And a small number of children can still struggle with vision problems, mild in the vast majority of cases. But in some rare cases, we can have a severe impairment. And sometimes we can also have recurrence of this condition. So we can treat this, but this can reappear. And usually happens within the first one, two years after the initial phase. And we haven't found actually any significant risk factors apart from the, from the opening pressure. I mean, if the opening pressure in the very beginning was higher, this is a risk factor for recurrence of symptoms. But yes, this can happen sometimes. It can be up to 20% in, in some studies, so we need to have it in mind and make families aware of this likelihood and also have it in mind and have a more long term follow up of those children.
SA: Let's round up with some quick fire questions. So firstly, are there any exam questions that you suspect might pop up around this subject?
MG: I think that questions would include symptoms of increased intercranial pressure. Differential diagnosis of headaches. So this can be in combination with diagnosing another headache disorder. We can have questions about clinical history. So it would be helpful to remember all those potential causes and the investigations which need to be, to be done. And questions which can also emerge will be about management, how we treat this condition either from a medication point of view or what other options are available.
SA: And you might also get questions about explaining to parents why you would do a lumbar puncture, for example.
MG: Yes. Yes. Of course.
SA: So secondly, are there any useful resources that you might recommend?
MG: There is a website idiopathic intercranial hypertension, which is iih.org.uk. Then they can find the useful resources for families as well. And uh, the British Paediatric Neurology Association has launched a very good webinar about increased intracranial hypertension. So this can be accessed via a BPNA website from those who are registered with the, with the association.
SA: Fantastic. And finally, what are your three takeaway learning points?
MG: First uh, learning point would be to make sure that we protect the vision of the child. Visual impairment is the most severe complication, so we need to have examination by an ophthalmologist as well, and a long term follow up by ophthalmologists.
Second, we need to totally differentiate idiopathic from secondary intracranial hypertension and it is necessary to have in mind that idiopathic intracranial hypertension is a very rare condition, as I said actually. So let's not rush to put the label before we are sure we have exhausted all other causes.
And the last one we need to have normal CSF to diagnose idiopathic intercranial hypertension, so let's pay details to results, even if they are marginally beyond the normal ranges.
SA: Amazing. Thank you so much, Maria.
MG: You're welcome, Sarah. It was a pleasure.
SA: Thank you for listening to this episode of Master the MRCPCH. We would love to get your feedback on the podcast and any ideas you may have for future episodes. You can find link to the feedback page in the episode description, or email us at digital
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