What is Pediatric Cerebral Aneurysm?
The earliest recorded case of an aneurysm in a child was a 15-year-old boy, reported by German pathologist Eppinger in 1871. After examining the body, Eppinger found a certain narrowness in the aortic isthmus (the part of the aorta, the largest artery in the body) and unusually, free blood at the brain’s base from a burst “saccular” aneurysm (a bulge in an artery wall) in the right anterior cerebral artery.
Years later, Edvard Bull reported the first case of an aneurysm diagnosed while a person was still alive: a 17-year-old girl with a severe headache and a problem with her third nerve, affecting her eye movements. An autopsy confirmed a ruptured aneurysm in the artery communicating towards the back of her brain.
While certain “acquired” factors like diabetes, alcohol use, high blood pressure, eating a diet high in fat and cholesterol, obesity, smoking, and oral contraceptive use are linked to subarachnoid hemorrhage (bleeding in the space between the brain and the brain’s surrounding membrane) in adults, these factors have little to no impact in children. To explain aneurysms in children, several experts suggest that congenital factors (conditions present from birth) might play a larger role.
What Causes Pediatric Cerebral Aneurysm?
Idiopathic aneurysms refer to bulging blood vessels with unknown cause. They occur in our body’s pipe system (vascular system), particularly in the brain. As more work was done to study the brain’s blood vessels after the patients have passed away, some interesting observations were made. Scientists found several structural defects in major points where arteries divide (bifurcations).
These aneurysms are like pouches where the muscle layer that normally holds the structure is missing but other layers continue to wrap around. Noticed inside these pouches is typically an internal lining, fibrous tissue, inflammation and possible bleeding of different ages. Plus, there could be early signs of hardening of the arteries. Interestingly, the point where the rupture mostly occurs usually has a small side pocket nearby.
Just as in adults, it seems that aneurysms in children look and behave similarly. It is noticed that they mostly happen where the big internal carotid artery divides into branches. These spots are more prone to injury from high-speed blood flow and present more significant structural weaknesses. Yet, we still don’t know what exactly leads to these irregularities.
In children, aneurysms are found to have connections with diseases related to collagen (a strengthening protein) and connective tissue. This could be due to the specific structure of the brain’s blood vessels which have thin walls and lack of surrounding support. If patients have an insufficient type III collagen, a protein needed to bear the pressure of blood flow, the vessel walls may become more flexible. This could result in larger aneurysms in children.
Moreover, another theory pointed out that childhood aneurysms might have roots in the vascular structure of the fetus. As the network matures into the adult arterial system, some smaller vessels disappear, leaving behind their stumps which might become aneurysms over the years.
Yet, there’s not enough proof to validate this theory fully. Some believe the lesions could be mainly inborn (congenital), while others consider that damage from high blood pressure, birth injury, trauma and insults while still in the womb play a role.
Stress from flowing blood on weakened blood vessels may also cause aneurysms to form in individuals who have a predisposition since birth. But in truth, most children with brain aneurysms rarely exhibit weakening of their blood vessels nearby. Most are not hypertensive (have high blood pressure) too. However, some children with aortic coarctation (a narrowing of the large blood vessel that leads from the heart) or a kidney condition called polycystic kidney disease do show high blood pressure together with aneurysms.
A consensus forms around the idea that inborn defects or acquired damage to the vessel wall may cause malfunctions in the vessel structure. How these defects or damage and the blood vessel’s ability to repair define whether an aneurysm forms or not.
Next we have traumatic aneurysms. These are caused after a close head injury, causing subsequent formation of an aneurysm due to the injury to the vessel walls. These often occur in specific areas of the brain where injury is most likely.
Infectious aneurysms, on the other hand, are often caused by bacteria, rather than fungi. These bacteria include Alpha Streptococcus, Staphylococcus, Pseudomonas, and Haemophilus, which are most frequently found in children with bacterial brain aneurysms.
Risk Factors and Frequency for Pediatric Cerebral Aneurysm
Cerebral aneurysms in children are quite rare, with studies suggesting an occurrence rate of about 1 to 3 cases per 1 million population. These often show up from birth to age 6 and again between ages 8 and adolescence, with a high number of cases happening within the first two years of life. These aneurysms are often found in specific areas of the brain such as the middle cerebral artery, its distal branches, and the vertebrobasilar system.
In terms of gender, aneurysms are slightly more common in males during childhood, with a male to female ratio of around 1.3 to 2.8:1. Among adults it’s more common in women, especially those above 70 years, but before age 40, the incidence is equal in both genders. When it comes to giant aneurysms, around 62% occur in boys.
An area where childhood aneurysms differ greatly from adult ones is their location; while carotid bifurcation aneurysms represent 29 to 54% of all cases in children, they account for just 4.4 to 4.5% in adults. Also, the presence of multiple aneurysms is much less common in children (around 4 to 5% of cases) than in adults (10 to 20%), due to the relationship between hypertension and the formation of multiple intracranial aneurysms.
When multiple aneurysms are found in children, they are usually linked with factors such as previous cranial irradiation, moyamoya disease, fibromuscular dysplasia, sickle cell disease, cardiac myxoma or arteriovenous malformations.
Signs and Symptoms of Pediatric Cerebral Aneurysm
Cerebral aneurysms can occur in both adults and children. For those who don’t know, aneurysms are balloon-like bulges in the blood vessels in the brain. While there are specific nuances in the cases of pediatric aneurysms, many of the symptoms and presentations of aneurysms are similar across all age groups. The most common initial sign of a cerebral aneurysm is a type of stroke known as subarachnoid hemorrhage (SAH). This appears in both adults and children.
SAH symptoms typically emerge rapidly and can include things like a severe headache, vomiting, and changes in consciousness including seizures and even coma. On occasion, some patients might experience minor warning symptoms like an unusually severe headache. When left undiagnosed, aneurysms can cause a number of neurological issues, or symptoms related to pressure buildup in the brain, due to their size or location.
- Severe and sudden headache
- Vomiting
- Changes in consciousness
- Seizures or coma
- Unusual severe headache as a warning symptom
- Neurological issues due to size or location of the aneurysm
If a cerebral aneurysm ruptures in children, there’s an estimated mortality rate of about 11 to 20% after the initial bleeding episode. This rate goes higher for adults. In the case of repeated bleeding, the mortality rate spikes to 25%. There’s also a possibility of mass symptoms manifesting in children signaling increased pressure in the brain. Such symptoms and the accompanying complications, like blockage of cerebrospinal fluid, are more common in children below 5 years and in cases where the aneurysm is unusually large.
If an aneurysm ruptures, the event can also, unfortunately, lead to strokes that are caused when blood escapes into the surrounding brain tissue (intracerebral hemorrhage). This has a higher risk of mortality and worse overall prognosis. Neurological complications may also appear due to compression from an enlarging aneurysm, hematoma formation, or buildup of fluid.
While seizures are common for kids with arteriovenous malformations (abnormal connections between arteries and veins), they’re less common for an unruptured aneurysm. Anywhere from 15 to 25% of children with a specific type of stroke – subarachnoid hemorrhage – may experience seizures. These seizures usually happen within 24 hours of the initial bleeding but can sometimes lead to a long-term seizure disorder.
Testing for Pediatric Cerebral Aneurysm
If a child doesn’t show symptoms but has a higher risk of developing a brain aneurysm, due to either a strong family history of aneurysms or certain conditions like Ehlers-Danlos syndrome, FMD or polycystic kidney disease, a CT-angiogram or an MR-angiogram can be used as an initial screening tool. MR imaging and angiography are capable of showing larger abnormalities in the blood vessels of the brain, but cerebral angiography is still considered the best method for pinpointing the exact location of brain aneurysms.
If a brain aneurysm has ruptured, different tests like a lumbar puncture or CT/MR imaging are important in evaluating the presence of blood in the brain. In most cases, blood can be detected with a non-contrast CT scan when performed within the first 2 days after the bleeding has occurred. This method, however, becomes less reliable after about 5 days. CT or MR angiography are especially helpful for identifying larger cerebral aneurysms, while ultrasound can effectively be used in very young infants. Ultrasound can also help reveal additional conditions such as hydrocephalus (accumulation of fluid in the brain), hematoma (a collection of blood outside of blood vessels), shift, and brain swelling.
Doctors usually delay performing a lumbar puncture until imaging studies have ruled out the presence of a hematoma or brain swelling, or unless there’s clear evidence of increased pressure in the brain. If a CT scan shows bleeding in the brain, a lumbar puncture isn’t needed. If the imaging results don’t show any bleeding and there’s no sign of increased pressure in the brain, a sample of cerebrospinal fluid can be taken to confirm cases that are still in doubt.
When subarachnoid hemorrhage (bleeding in the space between the brain and the surrounding membrane) has been confirmed in a child, a thorough cerebral angiogram should be performed. This process often requires general anesthesia for children below 6 years of age. Although there’s a debate about the timing of the angiogram, studies show that there’s no increase in complications whether it’s done immediately after the bleeding or later. In fact, some large studies have shown lower complications with immediate studies.
Despite its effectiveness, cerebral angiography only shows the cause of the bleeding in 50-70% of cases. If an aneurysm isn’t detected in the initial study, a repeat study after 2 weeks will show it in 10-20% of cases. There are times when a brain aneurysm can’t be detected in a person who has confirmed bleeding in the brain. In such cases, other possible causes need to be considered. Some of these may include leukemia, idiopathic thrombocytopenic purpura, a blood disease in newborns, various hemophilia disorders, and other bleeding disorders.
Treatment Options for Pediatric Cerebral Aneurysm
If a child has a suspected brain aneurysm, it’s crucial to begin medical treatment straight away to prevent complications. One of the biggest concerns is potential rebleeding, which can have severe consequences. Sometimes, it’s necessary to carry out a procedure to divert the flow of cerebrospinal fluid — the fluid that surrounds the brain and spinal cord — especially if it’s accumulating and causing a condition named hydrocephalus. However, this needs to be done with care, as the shift in pressure can risk the aneurysm rupturing.
During their hospital stay, the child’s fluid levels will be monitored closely through a urinary catheter, and they will typically have an arterial line. There’s a delicate balance to strike between providing enough pain relief and sedation to manage the child’s distress, while also ensuring frequent neurological check-ups can be performed. Allowing the parents to stay with the child can also help lessen any fear or anxiety.
To control the child’s blood pressure, they might need antihypertensive medications like calcium channel blocker, beta-blockers, and vasodilators. Anti-seizure medication is often given to prevent seizures that could cause additional problems. Stool softeners, breathing treatments, and anti-nausea medication can also help manage intracranial pressure, reducing the likelihood of worsening symptoms due to straining, coughing, or vomiting.
In some cases, calcium channel blockers may help prevent severe neurological deficits linked with vasospasms (a sudden constriction of blood vessels). If the vasospasm is severe enough, additional measures like volume expansion, hyperdynamic therapy, and hemodilution may be required.
It’s also important to watch out for and prevent other potential complications such as gastrointestinal bleeding, pulmonary edema (fluid buildup in the lungs), and high blood sugar levels. If there’s a suspected infection, antibiotics are required. An unnoticed drop in sodium levels in the blood, which can worsen consciousness level, increase seizure activity, and exacerbate cerebral edema (brain swelling), should also be avoided. This can usually be managed by oral sodium supplements and hypertonic intravenous saline, along with volume expansion.
While medical management is important, surgery or endovascular intervention (procedures involving the blood vessels) is usually the definitive treatment for a brain aneurysm. That said, some aneurysms may naturally clot over time, so a more conservative, watchful approach may be appropriate in some cases.
In certain cases involving ‘mycotic’ aneurysms, which are caused by infection, antibiotic treatment can sometimes be used instead of surgery. This may particularly be the case if the child has multiple aneurysms or a preexisting heart condition. If antibiotics are used, the aneurysm(s) need to be closely watched on scans every 2 to 3 weeks. If the aneurysm does not shrink or gets larger, surgical intervention might be needed.
If the child is critically unwell, it might be safer to delay surgery for a week or two to allow them to stabilize. However, the timing for surgery can vary based on each individual case. Typically, if the child is in a stable condition, the surgery should be performed as soon as possible to eliminate the aneurysm and prevent further complications.
From a technical perspective, the surgery to remove the aneurysm is somewhat like the one performed in adults, however, the smaller size of structures in children and their lower tolerance for changes in body temperature, blood loss, or fluid shifts due to their smaller size makes the procedure more challenging. The large size, and often unusual locations, of pediatric aneurysms, mean that direct elimination of the aneurysm isn’t always straightforward and might require innovative procedures.
What else can Pediatric Cerebral Aneurysm be?
When dealing with the treatment of acute conditions related to the circulatory system in the brain, several factors or conditions may be considered:
- Management of sudden stroke
- Anisocoria (unequal size of the eyes’ pupils)
- Stroke affecting the front part of the brain
- Aphasia (difficulty with language)
- Apraxia (difficulty with motor activities, despite having the ability)
- Blockage in the main artery at the back of the brain
- Stroke caused by a clot from the heart
- Use of ultrasound to check the carotid arteries in the neck
- Conditions affecting the large veins in the brain (Cavernous sinus syndrome)
- Bleeding in the part of the brain responsible for balance and coordination (cerebellar hemorrhage)
