Subarachnoid hemorrhage (SAH) is a life-threatening type of stroke caused by bleeding into the space surrounding the brain. This space, called the subarachnoid space, lies between the brain and the thin tissues that cover it. When bleeding occurs in this area, it can lead to serious complications including permanent brain damage or death if not treated immediately.
Recognizing the symptoms of subarachnoid hemorrhage quickly is crucial for survival and recovery. The condition often strikes without warning, typically affecting people between ages 40 and 65, though it can occur at any age. Understanding these warning signs can help you or a loved one seek emergency medical care promptly, which significantly improves outcomes.
This article explores the ten most critical symptoms of subarachnoid hemorrhage, their underlying causes, prevention strategies, and answers to frequently asked questions about this serious medical emergency.
1. Sudden, Severe Headache (Thunderclap Headache)
The hallmark symptom of subarachnoid hemorrhage is an extremely sudden and severe headache, often described as a “thunderclap headache.” This is not an ordinary headache—patients frequently describe it as the worst headache of their life, reaching maximum intensity within seconds to minutes.
This distinctive headache occurs when blood irritates the membranes covering the brain and increases pressure inside the skull. The pain is typically different from any headache the person has experienced before, both in intensity and in how quickly it develops. Unlike migraines or tension headaches that build gradually, a thunderclap headache strikes like a bolt of lightning.
The severity is often so intense that it may cause the person to cry out, clutch their head, or even collapse. Some patients describe it as feeling like they’ve been hit in the head with a hammer or like their head is exploding. This symptom requires immediate emergency medical attention, as every minute counts in preventing permanent brain damage.
2. Neck Stiffness and Pain
Neck stiffness, also known as nuchal rigidity, is another common and important symptom of subarachnoid hemorrhage. This occurs when blood in the subarachnoid space irritates the meninges—the protective membranes covering the brain and spinal cord—causing inflammation and muscle tension in the neck.
Patients typically find it difficult or impossible to bend their neck forward, bringing their chin toward their chest. The stiffness may develop within hours of the initial headache and is often accompanied by pain that radiates down the neck and into the shoulders. This is not the typical neck soreness from poor posture or sleeping wrong; it’s a profound rigidity that feels different and more severe.
The neck stiffness associated with SAH may be accompanied by a general feeling of discomfort throughout the spine. Healthcare providers often test for this symptom during physical examination as it’s a key indicator of meningeal irritation, which can signal bleeding in the brain.
3. Nausea and Vomiting
Nausea and vomiting frequently accompany subarachnoid hemorrhage, occurring in a significant majority of cases. These symptoms result from increased intracranial pressure caused by the accumulation of blood in the subarachnoid space and the brain’s reaction to this abnormal condition.
The vomiting associated with SAH is typically sudden, forceful, and may occur without much warning. Unlike gastrointestinal-related nausea that might be linked to something you ate, this nausea stems from the brain’s response to the hemorrhage and elevated pressure within the skull. It often occurs shortly after the onset of the severe headache.
These symptoms may be persistent and severe, not responding to typical anti-nausea remedies. When nausea and vomiting occur together with a sudden severe headache and neck stiffness, it forms a classic triad of symptoms that strongly suggests subarachnoid hemorrhage and warrants immediate emergency evaluation.
4. Loss of Consciousness or Altered Mental State
Many people experiencing a subarachnoid hemorrhage suffer from altered consciousness, ranging from mild confusion to complete loss of consciousness. Approximately 50% of SAH patients lose consciousness at some point, either briefly or for extended periods.
This symptom occurs when the bleeding affects brain function, either through direct damage, increased pressure on brain structures, or reduced blood flow to critical areas. The loss of consciousness may happen immediately when the hemorrhage occurs, or it may develop gradually as the condition progresses.
Altered mental state can manifest in various ways: confusion, disorientation, difficulty concentrating, memory problems, drowsiness, or difficulty staying awake. Some patients may become unresponsive or slip into a coma. Family members or bystanders might notice that the person seems “not themselves,” has trouble answering simple questions, or appears excessively sleepy. Any alteration in consciousness accompanying severe headache is a medical emergency.
5. Vision Problems and Disturbances
Vision problems are common in subarachnoid hemorrhage and can take several forms. Patients may experience blurred vision, double vision (diplopia), sudden vision loss in one or both eyes, or sensitivity to light (photophobia). These visual disturbances occur when bleeding affects the parts of the brain responsible for vision or when pressure on the optic nerves interferes with normal visual function.
Double vision specifically may result from pressure on the cranial nerves that control eye movement, causing the eyes to not align properly. Some patients report seeing floaters, having blind spots in their visual field, or experiencing a general dimming of vision. Photophobia, an abnormal sensitivity to light, is particularly common and causes significant discomfort when exposed to bright environments.
Sudden onset of any significant visual changes, especially when combined with severe headache, should never be ignored. The visual symptoms may be temporary or permanent depending on the extent of the hemorrhage and how quickly treatment is received. Even if vision problems seem to improve, medical evaluation is essential as the underlying hemorrhage still requires urgent attention.
6. Seizures or Convulsions
Seizures occur in approximately 10-25% of subarachnoid hemorrhage cases, typically within the first 24 hours after the bleeding begins. These seizures happen when blood irritates the brain tissue and disrupts normal electrical activity in the neurons, causing abnormal, excessive electrical discharges.
The seizures may present as generalized tonic-clonic seizures (formerly called grand mal seizures) with full-body convulsions, loss of consciousness, and muscle rigidity followed by rhythmic jerking movements. Alternatively, they might be focal seizures affecting only one part of the body or causing unusual sensations, movements, or behaviors without loss of consciousness.
Witnessing a seizure can be frightening, but it’s important to keep the person safe by protecting them from injury, turning them on their side if possible to prevent choking, and timing the seizure. Any seizure lasting more than five minutes, or multiple seizures occurring without the person regaining consciousness between them, is a medical emergency requiring immediate intervention. First-time seizures, especially in adults with no history of epilepsy, should always prompt emergency evaluation as they may indicate a serious underlying condition like SAH.
7. Weakness or Numbness in the Body
Sudden weakness or numbness, particularly affecting one side of the body, is a significant symptom of subarachnoid hemorrhage. This occurs when the bleeding affects areas of the brain responsible for motor control and sensation, or when blood vessels go into spasm (vasospasm), reducing blood flow to specific brain regions.
Patients may notice their arm or leg feeling heavy, weak, or completely unable to move. The face may droop on one side, similar to other types of stroke. Numbness or tingling sensations may affect the face, arm, leg, or entire side of the body. These symptoms may develop suddenly at the time of the hemorrhage or appear later as complications develop.
The weakness or numbness might be subtle at first—perhaps difficulty gripping objects, trouble lifting an arm, or a slight limp when walking. However, it can also be dramatic and complete, rendering a limb entirely useless. Any sudden onset of weakness or numbness, especially when accompanied by other SAH symptoms like severe headache, requires immediate emergency medical attention as it indicates that the brain is being affected by the bleeding.
8. Difficulty Speaking or Understanding Speech
Communication difficulties are another important symptom of subarachnoid hemorrhage, occurring when bleeding affects the language centers of the brain, typically located in the left hemisphere. These problems can manifest as difficulty producing speech, understanding what others are saying, or both.
Patients might struggle to find the right words (aphasia), speak in garbled or nonsensical sentences, or be completely unable to speak despite trying. They may understand what they want to say but cannot get the words out, which can be extremely frustrating and frightening. Alternatively, their speech might be fluent but make no sense, with made-up words or jumbled sentence structure.
Comprehension problems mean the person has difficulty understanding spoken language, following simple commands, or reading. They might respond inappropriately to questions or seem confused by simple requests. Slurred speech, as if intoxicated, can also occur due to weakness in the muscles controlling speech or due to brain dysfunction. Any sudden change in a person’s ability to communicate effectively is concerning and warrants urgent medical evaluation, particularly when combined with other symptoms of subarachnoid hemorrhage.
9. Sensitivity to Light (Photophobia)
Photophobia, or extreme sensitivity to light, is a frequent symptom of subarachnoid hemorrhage that causes significant discomfort. This occurs due to meningeal irritation from blood in the subarachnoid space, which triggers pain pathways in response to light stimulation.
Patients with photophobia find that exposure to light—whether natural sunlight or artificial indoor lighting—causes or worsens their headache and general discomfort. They typically prefer to remain in darkened rooms and may squint excessively, close their eyes, or cover their eyes when exposed to light. Even normal levels of brightness that wouldn’t bother them usually become intolerable.
This symptom often accompanies the severe headache and neck stiffness characteristic of SAH. The combination of these three symptoms—severe headache, neck stiffness, and photophobia—strongly suggests meningeal irritation, which can occur with bleeding in the subarachnoid space. While photophobia alone might occur with migraines or other conditions, its presence along with sudden severe headache and other neurological symptoms should raise immediate concern for subarachnoid hemorrhage.
10. Sudden Behavioral Changes and Confusion
Behavioral changes and confusion are important but sometimes overlooked symptoms of subarachnoid hemorrhage. These changes occur when the bleeding affects brain regions responsible for cognition, emotion, and behavior, or when increased intracranial pressure disrupts normal brain function.
Family members might notice that their loved one is acting strangely, showing uncharacteristic irritability, agitation, restlessness, or anxiety. The person might appear confused, disoriented to time or place, or have difficulty recognizing familiar people. They may exhibit poor judgment, make inappropriate comments, or engage in unusual behaviors completely out of character for them.
Some patients become excessively drowsy or lethargic, showing little interest in their surroundings or activities they normally enjoy. Others might become combative or uncooperative without clear reason. Memory problems may surface, with difficulty recalling recent events or forming new memories. These behavioral and cognitive changes can range from subtle to dramatic, but any sudden, unexplained personality or behavioral change, especially in the context of severe headache or other neurological symptoms, should be taken seriously and evaluated emergently.
Main Causes of Subarachnoid Hemorrhage
Understanding the causes of subarachnoid hemorrhage helps in recognizing risk factors and potentially preventing this serious condition. The main causes include:
Ruptured Brain Aneurysm: This is the most common cause, accounting for approximately 85% of spontaneous subarachnoid hemorrhages. An aneurysm is a weak, bulging area in the wall of a blood vessel in the brain. When it ruptures, blood spills into the subarachnoid space. Aneurysms can develop due to genetic factors, high blood pressure, smoking, or vessel wall weakness.
Arteriovenous Malformation (AVM): An AVM is an abnormal tangle of blood vessels connecting arteries and veins in the brain. These malformations are usually present from birth but may not cause problems until they rupture, leading to bleeding in the subarachnoid space. AVMs account for a smaller percentage of SAH cases but are more common in younger patients.
Head Trauma: Traumatic brain injury from accidents, falls, or physical assault can cause bleeding into the subarachnoid space. This type of SAH, called traumatic subarachnoid hemorrhage, differs from spontaneous SAH caused by aneurysm rupture and often occurs alongside other brain injuries.
Bleeding Disorders: Conditions that affect blood clotting, such as hemophilia or thrombocytopenia, can increase the risk of spontaneous bleeding in the brain. Use of blood-thinning medications (anticoagulants) also raises the risk of hemorrhage.
Blood Vessel Abnormalities: Other vascular abnormalities beyond aneurysms and AVMs, such as arterial dissection (a tear in the artery wall), vasculitis (inflammation of blood vessels), or moyamoya disease, can occasionally cause subarachnoid hemorrhage.
Prevention Strategies
While not all cases of subarachnoid hemorrhage can be prevented, especially those related to congenital abnormalities, several strategies can significantly reduce your risk:
Control High Blood Pressure: Hypertension is a major risk factor for aneurysm formation and rupture. Regular blood pressure monitoring and management through lifestyle changes and medications (as prescribed by your doctor) is crucial. Maintain blood pressure below recommended levels through diet, exercise, stress management, and medical treatment when necessary.
Quit Smoking: Smoking significantly increases the risk of developing brain aneurysms and their rupture. Tobacco use weakens blood vessel walls and raises blood pressure. Quitting smoking is one of the most important steps you can take to reduce SAH risk. Seek support through cessation programs, counseling, or consult your healthcare provider about safe approaches to quit.
Limit Alcohol Consumption: Excessive alcohol intake can raise blood pressure and contribute to aneurysm formation. If you drink alcohol, do so in moderation. Heavy drinking or binge drinking should be avoided as they pose additional risks to vascular health.
Avoid Illicit Drugs: Cocaine and other stimulant drugs can cause sudden, severe spikes in blood pressure that may trigger aneurysm rupture. Avoiding these substances eliminates this significant risk factor.
Maintain a Healthy Lifestyle: Regular exercise, a balanced diet rich in fruits and vegetables, maintaining a healthy weight, and managing stress all contribute to better cardiovascular health and reduced risk of vascular problems. Physical activity helps control blood pressure, weight, and overall vessel health.
Genetic Screening and Monitoring: If you have a family history of brain aneurysms or subarachnoid hemorrhage (two or more first-degree relatives affected), discuss screening options with your doctor. Imaging studies such as MRI or CT angiography can detect unruptured aneurysms, which might be monitored or treated preventively depending on their size, location, and other factors.
Manage Underlying Health Conditions: Proper management of conditions like diabetes, high cholesterol, and connective tissue disorders helps maintain vascular health and reduces complications that could lead to SAH.
Safety Measures to Prevent Head Trauma: Wear appropriate protective gear during sports and recreational activities, use seatbelts in vehicles, prevent falls at home (especially for elderly individuals), and take workplace safety precautions seriously to minimize the risk of traumatic brain injury.
Frequently Asked Questions
What is the survival rate for subarachnoid hemorrhage?
The survival rate varies depending on the severity of the hemorrhage and how quickly treatment is received. Approximately 10-15% of people die before reaching the hospital. Of those who receive medical care, about 25% die within 24 hours, and around 40-50% die within 30 days. However, those who survive the initial event and receive prompt, appropriate treatment can have good recovery outcomes. Early recognition and immediate emergency care significantly improve survival chances.
Can you have a subarachnoid hemorrhage and not know it?
In rare cases, a very small bleed or a “warning leak” from an aneurysm might cause only mild symptoms that someone might dismiss or attribute to other causes like a tension headache. However, most subarachnoid hemorrhages cause dramatic symptoms, particularly the characteristic thunderclap headache, that are impossible to ignore. Any sudden, severe headache that feels different from your normal headaches should prompt immediate medical evaluation, even if other symptoms are mild.
How quickly do subarachnoid hemorrhage symptoms appear?
The hallmark symptom—the thunderclap headache—typically appears suddenly, reaching maximum intensity within seconds to minutes. Other symptoms like neck stiffness, nausea, vomiting, and vision problems usually develop within minutes to hours of the initial hemorrhage. Some symptoms, such as confusion or weakness, might develop gradually over hours as complications progress. The sudden, dramatic onset of symptoms is characteristic of SAH and distinguishes it from conditions that develop more slowly.
Is subarachnoid hemorrhage the same as a stroke?
Subarachnoid hemorrhage is a type of stroke, specifically a hemorrhagic stroke. Strokes are divided into two main categories: ischemic strokes (caused by blockage of blood flow) and hemorrhagic strokes (caused by bleeding). SAH is a hemorrhagic stroke where bleeding occurs in the subarachnoid space around the brain, as opposed to intracerebral hemorrhage where bleeding occurs within the brain tissue itself. While all SAH events are strokes, not all strokes are subarachnoid hemorrhages.
What age group is most at risk for subarachnoid hemorrhage?
Subarachnoid hemorrhage most commonly affects people between ages 40 and 65, with the peak incidence around age 50-60. However, it can occur at any age, including in children and young adults, particularly when caused by arteriovenous malformations or trauma. Women have a slightly higher risk than men, especially after menopause. The risk increases with age, but having risk factors like smoking, high blood pressure, or a family history can increase risk at any age.
Can stress cause a subarachnoid hemorrhage?
Stress alone does not directly cause subarachnoid hemorrhage. However, stress can contribute indirectly by raising blood pressure, and sudden spikes in blood pressure can trigger rupture of an existing aneurysm. Activities that cause sudden, extreme increases in blood pressure—such as heavy lifting, straining, intense physical exertion, or severe emotional stress—may act as triggers if an aneurysm is already present. Managing chronic stress and avoiding sudden extreme exertion can help reduce risk, especially for those with known aneurysms.
Are there warning signs before a subarachnoid hemorrhage occurs?
In some cases, people experience what’s called a “sentinel headache” or “warning leak” days to weeks before a major subarachnoid hemorrhage. This occurs when an aneurysm leaks a small amount of blood. The warning headache is typically sudden and severe, though less intense than the thunderclap headache of a full rupture. Other warning signs might include sudden eye pain, double vision, or vision changes. However, many people have no warning signs at all before SAH occurs. Any sudden, unusual, severe headache should be evaluated immediately rather than waiting to see if it worsens.
How is subarachnoid hemorrhage diagnosed?
If SAH is suspected, emergency medical providers will perform imaging tests. A CT scan (computed tomography) of the head without contrast is usually the first test and can detect blood in the subarachnoid space in most cases, especially within the first 24 hours. If the CT scan is negative but suspicion remains high, a lumbar puncture (spinal tap) may be performed to check for blood or breakdown products of blood in the cerebrospinal fluid. Additional imaging such as CT angiography, MR angiography, or catheter cerebral angiography may be used to identify the source of bleeding, such as an aneurysm.
What should I do if I suspect someone is having a subarachnoid hemorrhage?
Call emergency services immediately (911 in the United States). Do not wait to see if symptoms improve. While waiting for emergency responders, keep the person calm and still, loosen any tight clothing, and position them comfortably. If they’re conscious, slightly elevating the head may help. If they lose consciousness, ensure their airway is open and place them in the recovery position (on their side) to prevent choking if vomiting occurs. Do not give them any food, drink, or medication. Time is critical—the sooner treatment begins, the better the chances of survival and recovery.
References:
- Mayo Clinic – Subarachnoid Hemorrhage
- National Institute of Neurological Disorders and Stroke – Cerebral Aneurysms
- Johns Hopkins Medicine – Subarachnoid Hemorrhage
- American Stroke Association – Hemorrhagic Strokes
- National Center for Biotechnology Information – Subarachnoid Hemorrhage
- NHS – Subarachnoid Haemorrhage
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