What is Charcot-Bouchard Aneurysm?
Charcot-Bouchard aneurysms are tiny blood vessel abnormalities in the brain. They’re so small that their diameter is less than 300 micrometers. They are most often found in specific small blood vessels called the lenticulostriate branches (LSAs) of the middle cerebral artery (MCA). LSAs are like small offshoots from the MCA, numbering anywhere between 2 to 12, on average around 8. They’re usually found close to the internal carotid artery and are responsible for blood supply to various parts of the brain like basal ganglia, which includes certain areas such as the putamen and the caudate, and then the thalamus, pons, and cerebellum.
The term “Charcot-Bouchard” comes from a French doctor named Jean-Martin Charcot and his student Charles Joseph Bouchard, who identified these aneurysms back in the 19th century. Then, in the 1960s, other researchers used advanced techniques to prove their existence. However, it’s still a debated topic whether the rupture of these aneurysms actually causes the bleeding in the brain.
People with long-term high blood pressure are more likely to develop these aneurysms. This is because chronic high blood pressure can weaken the blood vessel walls, causing the development of small ballooning (microaneurysms) in LSAs, which are highly prone to bursting. If these burst, they bleed into the brain tissue, causing what’s called an intraparenchymal hemorrhage or, more generally, an intracerebral hemorrhage. Symptoms generally help identify where the bleeding is located. Typically, a head CT scan without contrast is the first diagnostic test performed to see where the bleeding is. Treatment depends on how severe the hemorrhage is and where it has occurred, ranging from simple monitoring to surgical intervention.
What Causes Charcot-Bouchard Aneurysm?
Chronic high blood pressure is the most important factor that increases the risk of developing Charcot Bouchard aneurysms, tiny bulges in the blood vessels in the brain, that may burst and lead to bleeding. We can group the risk factors into two categories: those you can control and those you cannot.
Things you can control include:
* High blood pressure
* Eating a diet high in fat
* Being overweight (especially carrying excess weight around the waist)
* Smoking
* Heavy alcohol use
* Having low levels of low-density lipoprotein (the “good” cholesterol) and high levels of triglycerides (a type of fat) in your blood
* Using illegal drugs like cocaine or heroin
Things you can’t control are:
* Getting older
* Being a man
* Your race or ethnicity – Asians and African Americans are at a higher risk
Diseases like chronic kidney disease, cerebral amyloid angiopathy (a brain condition caused by abnormal deposits of protein), vascular malformations (abnormalities in blood vessels), and coagulopathies (blood clotting disorders) also increase your risk. These can be inherited, caused by other factors, or due to certain types of drugs like warfarin and antiplatelet medications that affect how your blood clots. All these factors can increase your chances of developing tiny aneurysms and brain bleeding.
Risk Factors and Frequency for Charcot-Bouchard Aneurysm
Intracerebral hemorrhage, a type of stroke, makes up 10 to 20% of all strokes globally and approximately 8 to 15% of all strokes in the United States. The risk of experiencing a stroke in a lifetime, for people aged 25 and older, was around 24.9% in 2016, slightly higher than the 22.8% risk in 1990. Men had a 24.7% risk, and women a slightly bigger risk at 25.1%.
Regions like East Asia and Europe have the highest risk, while areas with a lower sociodemographic index, like Sub-saharan Africa, have the lowest risk. Rates of stroke and stroke-related deaths are highest in Asia, notably in China and East European countries. Despite a decline in rates, the actual number of stroke cases in 2016 was double what it was in 1990. Most of these cases were in people under 70 years old.
- The estimated death rate from intracerebral hemorrhage is about 40% after a month and 54% after a year.
- Only 13 to 49% of patients achieve long-term functional independence.
Signs and Symptoms of Charcot-Bouchard Aneurysm
Doctors diagnose intracerebral hemorrhage by first asking the patient about when the symptoms started and how they have progressed. Symptoms can appear during physical activity, emotional stress, or even during rest in those with risk factors.
Common symptoms at the start can include:
- Headache caused by irritation of the meninges, the protective layers around the brain
- Vomiting, often forcefully, and nausea in about 50% of patients, due to increased pressure in the brain
- A reduced level of consciousness, with confusion or even coma depending on the size of the bleeding area. Coma is usually caused by very large bleeds squeezing the brain stem
- Seizures within the first 24 hours in around 10% of patients
Risk factors such as high blood pressure and the use of anticoagulant or antiplatelet medications are also investigated by doctors. Conditions like liver disease and cancer are important to consider as well, since they can alter how blood clots. For patients with a condition called cerebral amyloid angiopathy, cognitive problems may additionally be present.
An accurate measurement of vital signs, a baseline score of consciousness and cognitive function (GCS score), and a thorough physical exam with a detailed neurological assessment are required. The severity of symptoms can escalate rapidly as brain swelling increases and the size of the bleeding area enlarges. Symptoms varying based on where the bleeding is:
- When the putamen region of the brain is affected, it results in weakness on one side of the body and a decreased level of consciousness
- Thalamic bleeds cause numbness rather than weakness, along with difficulty moving the eyes upward
- Pontine bleeds result in very small pupils, weakness in all four limbs, issues with eye movement, and coma
- Lobar bleeds result in weaknesses, sensory deficits, and issues with speech
- Cerebellar bleeds cause dizziness, lack of coordination, and trouble moving the eyes together in the same direction
Testing for Charcot-Bouchard Aneurysm
Your doctor may conduct several tests if they suspect you have an intracerebral hemorrhage, a condition where bleeding occurs within your skull. These tests are necessary to understand your condition better and to give you the best possible treatment.
In the lab, your doctor may order a complete blood count to check for signs of infection and anemia. They might also check the functionality of your blood clotting system (PT, INR, aPTT), your lipid profile, electrolytes, creatinine, and liver function. It’s critical to determine your baseline glucose and HbA1c levels since they can indicate if you are at risk for, or already have hyperglycemia as a complication of your condition. They might test your blood for signs of bacterial infection if there is a reason to suspect you might have one.
Your doctor might also measure levels of a protein called cardiac-specific troponin. A higher level of this protein might indicate worse outcomes in patients with intracerebral hemorrhages. A urine toxicology screen is also important, since drugs like cocaine could contribute to this condition. If necessary, your doctor might conduct a lumbar puncture. This procedure involves placing a needle into your spinal canal to collect fluid for testing. This test is especially useful if an infection is suspected.
For imaging, a non-contrast CT scan of the head is usually the first choice. This scan can reveal the size, location, and nature of the bleeding in your brain. The appearance of the bleeding generally change over time: initially, it appears smooth and hyperdense (lighter), and after 48 hours, the blood collects and appears denser. At 72 hours, you might see a worsening of symptoms due to the increase in brain pressure, and the CT scan would show an area of decreased density due to swelling. Finally, after 3 to 20 days, the area of the bleeding shrinks and forms a ring-like appearance. If your symptoms worsen, you may need another CT scan to diagnose any complications.
Magnetic Resonance Imaging (MRI) of the brain might be performed to detect tiny areas of bleeding that appear as high-density areas surrounded by low-density boundaries. However, a non-contrast CT is performed to know whether the bleeding is new or old. Cerebral angiography, another imaging technique, is helpful in finding secondary causes of intracerebral hemorrhages, such as tiny aneurysms and arteriovenous malformations, which are abnormal connections between arteries and veins.
An electroencephalogram (EEG) might be performed on patients experiencing unexplained neurological decline or suspected seizures. An EEG tracks and records brain wave patterns, providing valuable information about your brain’s electrical activity.
Your doctor might also perform an electrocardiogram (ECG) to check for heart problems and irregularities in heart rhythm, which could impact your condition and treatment.
Treatment Options for Charcot-Bouchard Aneurysm
The treatment of a condition called intracerebral hemorrhage, which is bleeding within the brain, begins with ensuring the patient can breathe and has stable blood pressure and good blood flow. In cases where the patient is very unconscious (usually assessed by something called the Glasgow Coma Scale and scores less than 8), they may need help to breathe which is carried out by placing a tube in their windpipe (a procedure called intubation) followed by a machine (a ventilator) to assist with breathing. If the patient was previously taking any blood-thinning medications, these effects would need to be reversed.
Patients with this condition are at high risk of sudden worsening, especially within the first 24 hours, so they require close monitoring in an intensive care unit. It is important to carefully lower their blood pressure, keeping in mind that the brain should still receive enough blood flow. Doctors use different types of blood pressure-lowering medications, like nicardipine, clevidipine, labetalol, esmolol, enalaprilat, fenoldopam, and phentolamine.
After the patient’s condition is stabilized, a consultation with a neurosurgeon (a doctor who specializes in brain and nerve surgery) is necessary to check for high pressure within the brain. Medications like mannitol, hypertonic saline, or certain methods to assist breathing can be used when there’s a worsening of brain swelling in order to maintain enough blood flow to the brain. Sometimes, a surgery called decompressive craniectomy is done to help reduce the pressure caused by the bleeding, improve blood flow to the brain and also to stop inflammation caused by blood breakdown. This surgery can be particularly beneficial if the bleed is close to the brain surface, is of a specific size and if the patient is not in a coma.
If the bleeding has spread to the brain’s ventricles (fluid-filled spaces in the brain), this could block the natural flow of fluid, leading to a condition known as obstructive hydrocephalus. Treatment may require a procedure to drain the excess fluid. Also, if the patient has seizures or if the bleed is in certain areas of the brain, seizure-preventing medications such as phenytoin may be needed.
A few other important steps in care include raising the head of the bed to 30 degrees, managing body temperature to prevent fever, managing sugar levels in the blood, constant heart monitoring, managing problems with urine, ensuring the patient does not eat or drink through their mouth and providing nutrition through a tube, prevention of blood clot formation in the legs, preventing bedsores and minor sedation if needed to keep the patient comfortable.
So the main approach to managing this condition is to stabilize the patient, carefully lower blood pressure, ensure enough blood flow to the brain, and deal with any complications as they come up.
What else can Charcot-Bouchard Aneurysm be?
It’s very important to distinguish between two types of brain bleeds: intracerebral hemorrhages and lacunar hemorrhages. Intracerebral hemorrhages are caused by tiny bulges in your small brain arteries, also known as microaneurysms. On the other hand, lacunar hemorrhages happen due to a decrease in blood supply followed by a reflow of blood to the tissue, a condition known as ischemia and reperfusion injuries.
While both types are often linked to high blood pressure, certain other conditions are more common in people with lacunar hemorrhages. For instance, patients with this type of bleed are more likely to have type 2 diabetes and a higher body mass index.
What to expect with Charcot-Bouchard Aneurysm
It’s crucial to accurately predict the outcome for patients suffering from intracerebral hemorrhage (a sudden bleeding inside the brain). Estimating the prognosis wrongly could either result in unneeded surgical procedures and an extended hospital stay, or mistakenly limit the care a patient needs. Three key factors that can independently predict the worsening of neurological symptoms and likelihood of death are:
1. Hematoma expansion with perihematomal edema – This is when the pool of blood (hematoma) due to the bleeding inside the brain grows and causes swelling (edema) in the surrounding brain tissue.
2. Intraventricular hemorrhage – This is a condition where the bleeding occurs into the brain’s ventricles (fluid-filled spaces).
3. Hyperglycemia – This means high blood sugar levels.
Possible Complications When Diagnosed with Charcot-Bouchard Aneurysm
The complications of intracerebral bleeding, caused by the bursting of Charcot-Bouchard aneurysms, include a number of serious issues such as:
Hematoma Expansion
This is enlargement or rebleeding of the initial clot, and can significantly affect the sudden worsening of neurological function and likelihood of death. This expansion happens most within the first three hours but can continue up to a full day after the onset of symptoms. On CT scans, something called the “spot sign” indicates the bleeding is expanding. The varying look of the sign depends on the timing of the scan with relation to the first occurrence of symptoms. Treatment options for this condition could include clotting therapy with recombininant factor VIIa, careful lowering of blood pressure and surgical removal of the clot.
Perihematomal Edema
This is swelling around the affected area, which is caused by the process of the clot formation, and puts pressure on nearby structures. The swelling reaches its worst two weeks after symptoms first appear. Doctors aim to keep the pressure inside the skull from increasing too much by raising the head by 20-30 degrees, managing pain, controlling infection, giving sedatives and diuretics such as mannitol, and inducing hyperventilation as necessary.
Seizures
Seizures can both trigger and be a complication of intracerebral bleeding. They are managed with antiepileptic medication, chosen based on the individual patient’s needs and other medications.
Intraventricular Hemorrhage (IVH) With Hydrocephalus
If the bleeding expands to fill the ventricles in the brain, it could cause inflammation and damage to the area around the ventricles, the brain stem, and lead to fluid accumulation in the brain (hydrocephalus), which can cause the brain to squeeze (herniate). Draining the bleeding using an external ventricle drainage can be lifesaving. Stable clots can be broken up with clot-busting medication (low-dose alteplase). Lumbar drainage is a less invasive procedure with fewer complications for fluid accumulation caused by blockage between the ventricles.
Other problems which may occur include:
- Blood clots in the veins that could break off and block blood vessels in the lungs
- High blood sugar levels from stress
- Very high fevers from brain damage or infections
- High blood pressure from activation of the neuroendocrine systems
Preventing Charcot-Bouchard Aneurysm
It’s extremely important to set suitable blood pressure goals for patients depending on their age and to encourage them to consistently take their medication. Patients should also receive advice about changing certain habits that can contribute to high blood pressure. These may include smoking, consuming too much alcohol, or eating a diet high in fat.
Stroke symptoms can be hard to identify and because of this, patients (and their caretakers) might put off seeking medical help. This delay can limit the treatment options available. If blood flow to the brain is blocked for more than 4 to 6 hours, it can result in permanent damage. Surprisingly, studies show that only half of stroke patients seek medical help within the first 24 hours of noticing symptoms. This highlights the importance of educating patients (especially those with uncontrolled high blood pressure and multiple risk factors) about stroke symptoms. Recognizing symptoms like a headache accompanied with nausea and vomiting will encourage patients to get to the hospital quicker.