Subarachnoid Hemorrhage

What is Subarachnoid Hemorrhage?

Approximately 20% of strokes are a result of bleeding, split between two types: Subarachnoid Hemorrhage (SAH) and Intracerebral Hemorrhage (ICH), each accounting for 10% of cases. The subarachnoid space is an area between two protective layers of the brain: the arachnoid membrane and the pia mater. This area contains cerebrospinal fluid and blood vessels that nourish different parts of the brain.

A Subarachnoid Hemorrhage (SAH) occurs when blood accumulates in this area. There are two main causes of SAH. It can be nontraumatic, meaning it occurs on its own due to conditions like the rupturing of an aneurysm (which is the cause in approximately 85% of cases), or traumatic, meaning it’s the result of an injury. Here, we’ll focus on nontraumatic SAH. Aside from aneurysm rupture, there are other nontraumatic causes of SAH, but about 15-20% of patients who present with SAH do not have visible blood vessel lesions.

An SAH can be life-changing, often resulting in significant mortality and high rates of long-term effects in survivors. Ensuring the patient can breathe and circulate blood is the focus of initial care given before reaching a hospital with neurosurgery specialists. Patients commonly describe the sudden onset of an extremely severe headache, often referred to as the “worst headache of my life”.

Subsequent treatment options draw from controlled studies and are based on the specific individual’s symptoms and condition. An SAH often presents a long-term, complex health scenario with potential complications such as seizures, unusual constriction of blood vessels (vasospasm), excess cerebrospinal fluid in the brain (hydrocephalus) and delayed lack of enough blood supply to the brain (delayed cerebral ischemia).

What Causes Subarachnoid Hemorrhage?

As mentioned before, about 85% of nontraumatic SAH cases, or sudden brain bleeding not caused by trauma, happen due to an aneurysm rupture. The remaining 15 to 20% have different causes and often the reason for the bleeding is not found. Finding out the exact cause of the bleeding is very important because it helps doctors treat the problem accordingly. The most common reasons for nontraumatic SAH are:

1) Aneurysmal Subarachnoid Hemorrhage (aSAH): This type of bleeding is caused by an aneurysm, a bulging, weak spot in an artery wall. Risk factors include high blood pressure, smoking, and a family history of the condition. Drinking heavily, using drugs that stimulate the nervous system, and a lack of estrogen can also contribute. Factors that increase the risk of an aneurysm rupturing include old age (more than 60 years), location in the back of the brain, hardening of the arteries, high blood pressure, and a large aneurysm size (more than 5mm). Having a family history of aneurysms or SAH, a personal history of SAH, or a condition called autosomal dominant polycystic kidney disease also increase the risk.

2) Nonaneurysmal Subarachnoid Hemorrhage (NASAH): This type of bleeding isn’t caused by an aneurysm and includes:

i) Perimesencephalic nonaneurysmal subarachnoid hemorrhage: This type is identified by a specific pattern of localized blood visible on a CT scan, normal brain angiography (a type of X-ray), and a mild form of illness. Most NASAH cases fall under this subtype.

ii) Occult Aneurysm: Sometimes, a small aneurysm is missed during the early angiographic exams but is found during a repeat exam. This could be because of technical mistakes , small aneurysm size, or the aneurysm was hidden because of a spasm, blood clot, or bleeding in the aneurysm.

iii) Vascular Malformations: These are abnormal connections between blood vessels in the brain or spinal cord. They’re often seen during brain angiography. They are commonly managed with surgery or with techniques that involve inserting small devices into the blood vessels.

iv) Intracranial Arterial Dissection: This condition involves a tear in the wall of an artery within the brain. It can lead to a brain bleed, which is usually serious and damaging. It is typically diagnosed with conventional angiography and treated with surgery or non-surgical, endovascular techniques.

v) Other Causes: Other conditions that can cause SAH include cocaine abuse, cerebral amyloid angiopathy (an age-related brain disease), cerebral venous thrombosis (a blood clot in a vein in the brain), sickle cell disorders, moyamoya disease (a rare disorder of the blood vessels in the brain), inflammation of the brain’s blood vessels (vasculitis), and bleeding disorders.

Risk Factors and Frequency for Subarachnoid Hemorrhage

An aneurysmal subarachnoid hemorrhage (aSAH) is a condition that has a global occurrence rate of 7.9 people for every 100,000 people each year. The number of these cases has been decreasing over time. For instance, in 2010 the incidence of aSAH was 6.1 per 100,000 people, which was lower than the rate of 10.2 in 1980. For unexplained reasons, Japan and Finland have a higher number of these cases compared to other parts of the world.

aSAH commonly occurs in people between 40 and 60 years old, but it can also affect very young children and older adults.
The average age of people when their aneurysm ruptures is between 50 and 55 years old.
Black and Hispanic people are more likely to have this condition compared to white Americans.
The condition is slightly more common in females, which may be due to hormonal differences.
People who smoke or have had an aneurysm rupture in their brain before are at a higher risk of having an aSAH.

Signs and Symptoms of Subarachnoid Hemorrhage

A common symptom of subarachnoid hemorrhage is a severe headache. People usually describe this headache as the worst one they’ve ever experienced. This should signal the need for more detailed scans. The headache is frequently accompanied by nausea, often severe enough to cause projectile vomiting, neck stiffness, and sensitivity to light. Blood extending down into the fourth ventricle can lead to meningismus, which is characterized by these symptoms. As the blood continues to flow down the spinal cord, it may irritate the surrounding nerves causing neck pain and stiffness. A detailed examination is essential. If the person is showing any specific physical or mental deficits, it means the subarachnoid hemorrhage is more severe and it may affect the chances of their recovery. Those with a severe subarachnoid hemorrhage may become comatose, necessitating immediate evaluation and treatment since in some cases the coma can be reversible. Unruptured intracranial aneurysms or increased pressure in the skull after a rupture can cause cranial nerve palsies, particularly impacting the third and sixth cranial nerves. Some people may also experience seizures when an intracranial aneurysm ruptures.

Severe headache (often described as the worst one’s ever had)
Nausea
Projectile vomiting
Neck stiffness
Sensitivity to light
Pain and stiffness in the neck due to additional blood flow down the spinal cord
Need for a detailed examination
Possibility of a coma in severe subarachnoid hemorrhages
Effects on third and sixth cranial nerves caused by unruptured intracranial aneurysms or increased pressure in the skull post-rupture
Potential seizures upon rupture of an intracranial aneurysm

Testing for Subarachnoid Hemorrhage

If a doctor thinks a patient might have a subarachnoid hemorrhage, which is bleeding in the space surrounding the brain, they will first use a special X-ray test called a computed tomogram (CT) on the patient’s head. If this test shows that the patient does have a subarachnoid hemorrhage, the next step is to perform another type of CT test, called a CT angiography. This will help the doctor determine where the bleeding is coming from and how big the aneurysm (a weakened and bulging area in an artery) is.

If the initial Head CT doesn’t show any signs of bleeding, but the doctor still strongly suspects a subarachnoid hemorrhage, they might perform a lumbar puncture. This test, which is often called a spinal tap, involves taking a small sample of the fluid that surrounds the brain and spinal cord to look for signs of bleeding. Ideally, this test should be done about 6 hours after the initial Head CT. One of the things the doctor will be looking for is xanthochromia, which is a yellowish or pinkish color in the fluid due to the breakdown of red blood cells.

If the CT angiogram doesn’t show an aneurysm, the doctor may recommend another imaging test, such as a cerebral angiography or a digital subtraction angiography. If the patient is allergic to the contrast dye used in these tests or has kidney problems, the doctor will take steps to reduce the risk of a reaction. An alternative test that doesn’t require contrast dye is time-of-flight magnetic resonance angiography (TOF-MRA).

The ability of a CT scan to detect a subarachnoid hemorrhage, and the amount of red blood cells in the fluid sample, can change over time. This is because the cerebrospinal fluid (the fluid around the brain and spinal cord) moves around quite quickly, and over time, any red blood cells in this fluid will burst open, releasing substances like bilirubin and oxyhemoglobin. This process is what causes the color change seen in xanthochromia. So, the longer it has been since the suspected hemorrhage, the more likely it is for the test to pick up on xanthochromia.

Treatment Options for Subarachnoid Hemorrhage

Patients with aSAH, a type of stroke, should be cared for based on how severe their condition is. This often involves both medical treatments and procedures that can help prevent or manage complications. There are different approaches, some less invasive, for patients with less severe conditions. The main aim of treatment is to prevent further bleeding, manage pain, provide support, and deliver accurate diagnosis and treatment.

Soon after aSAH, common problems such as hydrocephalus, which is the buildup of fluid in the brain, and vasospasm, which is the narrowing of blood vessels, may occur. Hydrocephalus is found in up to 30% of patients who also have bleeding within the ventricles of the brain, the cavities containing the brain’s fluid. This happens because the fluid flow is blocked and there’s an inflammatory reaction caused by blood in the brain fluid. This reaction can eventually lead to a fibrous tissue growth.

Patients with a significant aSAH and a severe condition are more at risk of rebleeding. Hydrocephalus often happens within the first three days after a hemorrhage. As a response, an external device is placed inside the ventricles to relieve the pressure.

Another major complication in aSAH is the development of delayed cerebral ischemia (DCI), which is brain damage caused by insufficient blood flow to the brain. This happens when a patient has constriction and narrowing of blood vessels in the brain. Around 60% of aSAH patients have vasospasm that can be seen on medical imaging even without showing any signs or experiencing any symptoms. About 39% of patients experience symptoms of vasospasm.

Patients are kept stable through the use of osmotic diuretics, like Mannitol, and blood pressure controlling drugs until procedures can be performed to secure the IA, the bulging blood vessel causing the condition. More critically ill patients may need to be intubated and ventilated, ensuring their airways are clear and that they’re breathing. Other procedures to closely monitor the patient’s vital signs, urine, and to prevent seizures could also be needed.

Monitoring methods include Transcranial Doppler (TCD) sonography, which detects and monitors vasospasm. It can detect changes in velocity before the patients have symptoms of vasospasm. However, its effectiveness varies from operator to operator and it may not always be accurate. Typically, digital subtraction angiography is necessary to diagnose vasospasm and to start treatment.

Imaging studies such as CT angiography and CT perfusion can be useful in the initial stages of SAH, as they can detect narrowing of arteries or uneven blood flow. Their clinical utility is still being established.

Electroencephalography (EEG) can be used to detect unnoticed seizures, especially in patients with severe SAH who unexpectedly worsen or fail to improve. Patients should be checked once every one to two hours, as they are at high risk of delayed cerebral ischemia.

The significant concerns after an aSAH are rebleeding, hydrocephalus, and vasospasm. The risk of these conditions can be reduced by controlling the patient’s blood pressure. Further treatment may involve opioids to reduce the blood pressure and promote patient comfort. Non-opioid medications such as acetaminophen are first-line medications, while others like fentanyl, Dilaudid, and morphine sulfate may provide pain relief, sedation, and help decrease anxiety.

For aSAH, surgical clipping or endovascular coiling, procedures used to prevent or manage complications from a bulging or ruptured blood vessel, are the only effective treatments and should ideally be done as soon as possible, preferably within 24 hours.

When it comes to brain-related conditions, there are a various possibilities that doctors need to consider. These include:

Bacterial and tuberculous meningitis
Granulomatous meningitis
Neurosarcoidosis
Pseudo-subarachnoid hemorrhage

What to expect with Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH), a type of stroke, is linked to a high early death rate. A study conducted in 2017 established that about 18 percent of patients with SAH suddenly died before they could receive medical attention in a hospital. Among those who manage to get to the hospital alive, a substantial number of early deaths result from complications related to SAH such as initial bleeding, rebleeding, narrowing of blood vessels causing brain damage (vasospasm and delayed cerebral ischemia), water on the brain (hydrocephalus), increased pressure inside the skull, seizures, and heart complications.

Long-term complications of SAH can include problems with mental functions (neurocognitive dysfunction), epilepsy, and other specific neurological deficits, which means certain parts of the brain aren’t working properly. According to one patient registry, over 10 percent of patients with SAH remain either moderately or severely disabled.

Possible Complications When Diagnosed with Subarachnoid Hemorrhage

Convulsions or seizures
Narrowing of blood vessels (vasospasm)
Bleeding again (rebleed)
Build-up of fluid in the brain (hydrocephalus)
Increased pressure inside the skull (intracranial pressure)
Movement of the brain caused by pressure (brain herniation)
Death of brain cells due to lack of oxygen (cerebral infarction)
General medical complications
Fluid in the lungs caused by nerve damage (neurogenic pulmonary edema)
Potential death

Preventing Subarachnoid Hemorrhage

If a patient is diagnosed with an aneurysm, but the doctor has decided on a conservative or less invasive management, the patient should understand the potential complications if the aneurysm were to rupture or burst. This can be serious and life-threatening.

When a patient, or their relatives are admitted to the hospital due to a subarachnoid hemorrhage – which is bleeding in the space between the brain and the tissues that cover the brain, caused by the rupture of an aneurysm, they should be aware of the risk of the rupture happening again. It’s also important that they understand the potential health complications and risks (morbidity) and the risk of death (mortality) that can emerge from any further medical procedure or treatment.

Frequently asked questions

The prognosis for Subarachnoid Hemorrhage (SAH) can vary depending on the individual, but it is generally associated with a high early death rate. Approximately 18% of SAH patients die suddenly before receiving medical attention. Among those who make it to the hospital alive, there is a risk of complications such as initial bleeding, rebleeding, brain damage, hydrocephalus, seizures, and heart complications. Long-term complications can include neurocognitive dysfunction, epilepsy, and other neurological deficits, with over 10% of SAH patients remaining moderately or severely disabled.

The most common cause of Subarachnoid Hemorrhage (SAH) is an aneurysm rupture, which accounts for about 85% of nontraumatic SAH cases. Other causes include nonaneurysmal SAH, vascular malformations, intracranial arterial dissection, and other conditions such as cocaine abuse, cerebral amyloid angiopathy, cerebral venous thrombosis, sickle cell disorders, moyamoya disease, vasculitis, and bleeding disorders.

Signs and symptoms of Subarachnoid Hemorrhage include: - Severe headache, often described as the worst one's ever had. - Nausea. - Projectile vomiting. - Neck stiffness. - Sensitivity to light. - Pain and stiffness in the neck due to additional blood flow down the spinal cord. - Need for a detailed examination. - Possibility of a coma in severe subarachnoid hemorrhages. - Effects on third and sixth cranial nerves caused by unruptured intracranial aneurysms or increased pressure in the skull post-rupture. - Potential seizures upon rupture of an intracranial aneurysm.

The types of tests that are needed for Subarachnoid Hemorrhage include: 1. Computed Tomogram (CT) of the head: This special X-ray test is used to initially diagnose a subarachnoid hemorrhage. 2. CT angiography: If the initial CT scan shows a subarachnoid hemorrhage, a CT angiography is performed to determine the source of bleeding and the size of the aneurysm. 3. Lumbar puncture (spinal tap): If the initial CT scan does not show signs of bleeding but the doctor still suspects a subarachnoid hemorrhage, a lumbar puncture may be performed to analyze the fluid surrounding the brain and spinal cord for signs of bleeding. 4. Cerebral angiography or digital subtraction angiography: If the CT angiogram does not show an aneurysm, these imaging tests may be recommended to further evaluate the blood vessels. An alternative test is time-of-flight magnetic resonance angiography (TOF-MRA) which does not require contrast dye. 5. Electroencephalography (EEG): This test may be used to detect seizures in patients with severe subarachnoid hemorrhage. 6. Transcranial Doppler (TCD) sonography: This monitoring method can detect and monitor vasospasm, a common complication of subarachnoid hemorrhage. 7. CT angiography and CT perfusion: These imaging studies can be useful in the initial stages of subarachnoid hemorrhage to detect narrowing of arteries or uneven blood flow, although their clinical utility is still being established.

The conditions that a doctor needs to rule out when diagnosing Subarachnoid Hemorrhage are: - Bacterial and tuberculous meningitis - Granulomatous meningitis - Neurosarcoidosis - Pseudo-subarachnoid hemorrhage

The side effects when treating Subarachnoid Hemorrhage (SAH) can include: - Convulsions or seizures - Narrowing of blood vessels (vasospasm) - Bleeding again (rebleed) - Build-up of fluid in the brain (hydrocephalus) - Increased pressure inside the skull (intracranial pressure) - Movement of the brain caused by pressure (brain herniation) - Death of brain cells due to lack of oxygen (cerebral infarction) - General medical complications - Fluid in the lungs caused by nerve damage (neurogenic pulmonary edema) - Potential death

A neurosurgeon.

The global occurrence rate of Subarachnoid Hemorrhage is 7.9 people for every 100,000 people each year.

Subarachnoid Hemorrhage (SAH) is treated based on the severity of the condition. Treatment involves medical interventions and procedures to prevent or manage complications. Less invasive approaches are used for patients with less severe conditions. The main goals of treatment are to prevent further bleeding, manage pain, provide support, and deliver accurate diagnosis and treatment. Common complications of SAH include hydrocephalus and vasospasm. Hydrocephalus, the buildup of fluid in the brain, can be managed by placing an external device inside the ventricles to relieve pressure. Vasospasm, the narrowing of blood vessels, can be monitored using Transcranial Doppler sonography and diagnosed using digital subtraction angiography. Surgical clipping or endovascular coiling are the effective treatments for SAH and should ideally be done within 24 hours.

Subarachnoid Hemorrhage (SAH) is a type of stroke that occurs when blood accumulates in the subarachnoid space, which is the area between two protective layers of the brain. It can be nontraumatic, often caused by the rupturing of an aneurysm, or traumatic, resulting from an injury. SAH can have significant mortality and long-term effects, and initial care focuses on ensuring the patient's ability to breathe and circulate blood.