Subarachnoid hemorrhage (SAH) is
bleeding
Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...
into the
subarachnoid space
In anatomy, the meninges (, ''singular:'' meninx ( or ), ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in th ...
—the area between the
arachnoid membrane
The arachnoid mater (or simply arachnoid) is one of the three meninges, the protective membranes that cover the brain and spinal cord. It is so named because of its resemblance to a spider web. The arachnoid mater is a derivative of the neural cr ...
and the
pia mater
Pia mater ( or ),[Entry "pia mater"](_blank)
in
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...
.
[ Symptoms may include a severe headache of rapid onset, vomiting, ]decreased level of consciousness
An altered level of consciousness is any measure of arousal other than normal. Level of consciousness (LOC) is a measurement of a person's arousability and responsiveness to stimuli from the environment.
A mildly depressed level of consciousne ...
, fever
Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...
, and sometimes seizure
An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with los ...
s.[ Neck stiffness or neck pain are also relatively common.] In about a quarter of people a small bleed with resolving symptoms occurs within a month of a larger bleed.[
SAH may occur as a result of a ]head injury
A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of inju ...
or spontaneously, usually from a ruptured cerebral aneurysm
An intracranial aneurysm, also known as a brain aneurysm, is a cerebrovascular disorder in which weakness in the wall of a cerebral artery or vein causes a localized dilation or ballooning of the blood vessel.
Aneurysms in the posterior circul ...
.[ Risk factors for spontaneous cases include ]high blood pressure
Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
, smoking, family history, alcoholism, and cocaine
Cocaine (from , from , ultimately from Quechuan languages, Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly recreational drug use, used recreationally for its euphoria, euphoric effects. It is primarily obtained from t ...
use.[ Generally, the diagnosis can be determined by a ]CT scan
A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...
of the head if done within six hours of symptom onset.[ Occasionally, a ]lumbar puncture
Lumbar puncture (LP), also known as a spinal tap, is a medical procedure in which a needle is inserted into the spinal canal, most commonly to collect cerebrospinal fluid (CSF) for diagnostic testing. The main reason for a lumbar puncture is to ...
is also required.[ After confirmation further tests are usually performed to determine the underlying cause.][
Treatment is by prompt ]neurosurgery
Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the medical specialty concerned with the surgical treatment of disorders which affect any portion of the nervous system including the brain, spinal cord and peri ...
or endovascular coiling
Endovascular coiling is an endovascular treatment for intracranial aneurysms and bleeding throughout the body. The procedure reduces blood circulation to the aneurysm through the use of microsurgical detachable platinum wires, with the clinician in ...
. Medications such as labetalol
Labetalol is a medication used to treat high blood pressure and in long term management of angina. This includes essential hypertension, hypertensive emergencies, and hypertension of pregnancy. In essential hypertension it is generally less pr ...
may be required to lower the blood pressure until repair can occur.[ Efforts to treat fevers are also recommended.][ ]Nimodipine
Nimodipine, sold under the brand name Nimotop among others, is calcium channel blocker used in preventing vasospasm secondary to subarachnoid hemorrhage (a form of cerebral hemorrhage). It was originally developed within the calcium channel bl ...
, a calcium channel blocker
Calcium channel blockers (CCB), calcium channel antagonists or calcium antagonists are a group of medications that disrupt the movement of calcium () through calcium channels. Calcium channel blockers are used as antihypertensive drugs, i.e., as ...
, is frequently used to prevent vasospasm
Vasospasm refers to a condition in which an arterial spasm leads to vasoconstriction. This can lead to tissue ischemia and tissue death (necrosis). Cerebral vasospasm may arise in the context of subarachnoid hemorrhage. Symptomatic vasospasm or de ...
.[ The routine use of medications to prevent further seizures is of unclear benefit.][ Nearly half of people with a SAH due to an underlying aneurysm die within 30 days and about a third who survive have ongoing problems.][ Between ten and fifteen percent die before reaching a hospital.]
Spontaneous SAH occurs in about one per 10,000 people per year.[ Females are more commonly affected than males.][ While it becomes more common with age, about 50% of people present under 55 years old.][ It is a form of ]stroke
A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functionin ...
and comprises about 5 percent of all strokes.[ Surgery for aneurysms was introduced in the 1930s.] Since the 1990s many aneurysms are treated by a less invasive procedure called endovascular coiling
Endovascular coiling is an endovascular treatment for intracranial aneurysms and bleeding throughout the body. The procedure reduces blood circulation to the aneurysm through the use of microsurgical detachable platinum wires, with the clinician in ...
, which is carried out through a large blood vessel.
Signs and symptoms
The classic symptom of subarachnoid hemorrhage is thunderclap headache
A thunderclap headache is a headache that is severe and has a sudden onset. It is defined as a severe headache that takes seconds to minutes to reach maximum intensity. Although approximately 75% are attributed to "primary" headaches—headache d ...
(a headache described as "like being kicked in the head", or the "worst ever", developing over seconds to minutes). This headache often pulsates towards the occiput
The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cereb ...
(the back of the head). About one-third of people have no symptoms apart from the characteristic headache, and about one in ten people who seek medical care with this symptom are later diagnosed with a subarachnoid hemorrhage.[ Vomiting may be present, and 1 in 14 have ]seizure
An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with los ...
s.[ ]Confusion
In medicine, confusion is the quality or state of being bewildered or unclear. The term "acute mental confusion" , decreased level of consciousness or coma
A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal wake-sleep cycle and does not initiate voluntary actions. Coma patients exhi ...
may be present, as may neck stiffness and other signs of meningism
Meningism is a set of symptoms similar to those of meningitis but not caused by meningitis. Whereas meningitis is inflammation of the meninges (membranes that cover the central nervous system), meningism is caused by nonmeningitic irritation of t ...
.[
Neck stiffness usually presents six hours after initial onset of SAH.] Isolated dilation
Dilation (or dilatation) may refer to:
Physiology or medicine
* Cervical dilation, the widening of the cervix in childbirth, miscarriage etc.
* Coronary dilation, or coronary reflex
* Dilation and curettage, the opening of the cervix and surgic ...
of a pupil and loss of the pupillary light reflex
The pupillary light reflex (PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity (luminance) of light that falls on the retinal ganglion cells of the retina in the back of the eye, there ...
may reflect brain herniation
Brain herniation is a potentially deadly side effect of very high pressure within the skull that occurs when a part of the brain is squeezed across structures within the skull. The brain can shift across such structures as the falx cerebri, the te ...
as a result of rising intracranial pressure
Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury (mmHg) and at rest, is normally 7–15 Millimeter of mercury, mmHg ...
(pressure inside the skull).[ Intraocular hemorrhage (bleeding into the eyeball) may occur in response to the raised pressure: subhyaloid hemorrhage (bleeding under the ]hyaloid membrane
The vitreous membrane (or hyaloid membrane or vitreous cortex) is a layer of collagen separating the vitreous humour from the rest of the eye. At least two parts have been identified anatomically. The posterior hyaloid membrane separates the rear ...
, which envelops the vitreous body
The vitreous body (''vitreous'' meaning "glass-like"; , ) is the clear gel that fills the space between the lens and the retina of the eyeball (the vitreous chamber) in humans and other vertebrates. It is often referred to as the vitreous humor ...
of the eye) and vitreous hemorrhage may be visible on fundoscopy
Ophthalmoscopy, also called funduscopy, is a test that allows a health professional to see inside the fundus of the eye and other structures using an ophthalmoscope (or funduscope). It is done as part of an eye examination and may be done as part ...
. This is known as Terson syndrome
Terson syndrome or Terson's syndrome is the occurrence of a Vitreous humour, vitreous hemorrhage of the human eye in association with subarachnoid hemorrhage. Vitreous hemorrhage of the eye can also occur in association with intracranial hemorrhage ...
(occurring in 3–13 percent of cases) and is more common in more severe SAH.
Oculomotor nerve
The oculomotor nerve, also known as the third cranial nerve, cranial nerve III, or simply CN III, is a cranial nerve that enters the orbit through the superior orbital fissure and innervates extraocular muscles that enable most movements of ...
abnormalities (affected eye looking downward and outward and inability to lift the eyelid on the same side) or palsy Palsy is a medical term which refers to various types of paralysisDan Agin, ''More Than Genes: What Science Can Tell Us About Toxic Chemicals, Development, and the Risk to Our Children;; (2009), p. 172. or paresis, often accompanied by weakness and ...
(loss of movement) may indicate bleeding from the posterior communicating artery
In human anatomy, the left and right posterior communicating arteries are arteries at the base of the brain that form part of the circle of Willis. Each posterior communicating artery connects the three cerebral arteries of the same side. Anterior ...
.[ Seizures are more common if the hemorrhage is from an aneurysm; it is otherwise difficult to predict the site and origin of the hemorrhage from the symptoms.][ SAH in a person known to have seizures is often diagnostic of a ]cerebral arteriovenous malformation
A cerebral arteriovenous malformation (cerebral AVM, CAVM, cAVM) is an abnormal connection between the arteries and veins in the brain—specifically, an arteriovenous malformation in the cerebrum.
Signs and symptoms
The most frequently observed ...
.[
The combination of intracerebral hemorrhage and raised intracranial pressure (if present) leads to a "sympathetic surge", i.e. over-activation of the sympathetic system. This is thought to occur through two mechanisms, a direct effect on the ]medulla
Medulla or Medullary may refer to:
Science
* Medulla oblongata, a part of the brain stem
* Renal medulla, a part of the kidney
* Adrenal medulla, a part of the adrenal gland
* Medulla of ovary, a stroma in the center of the ovary
* Medulla of th ...
that leads to activation of the descending sympathetic nervous system
The sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of th ...
and a local release of inflammatory mediators that circulate to the peripheral circulation where they activate the sympathetic system. As a consequence of the sympathetic surge there is a sudden increase in blood pressure
Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" r ...
; mediated by increased contractility
Contractility refers to the ability for self-contraction, especially of the muscles or similar active biological tissue
*Contractile ring in cytokinesis
*Contractile vacuole
*Muscle contraction
**Myocardial contractility
*See contractile cell for ...
of the ventricle and increased vasoconstriction
Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vessel ...
leading to increased systemic vascular resistance
Vascular resistance is the resistance that must be overcome to push blood through the circulatory system and create flow. The resistance offered by the systemic circulation is known as the systemic vascular resistance (SVR) or may sometimes be ca ...
. The consequences of this sympathetic surge can be sudden, severe, and are frequently life-threatening. The high plasma
Plasma or plasm may refer to:
Science
* Plasma (physics), one of the four fundamental states of matter
* Plasma (mineral), a green translucent silica mineral
* Quark–gluon plasma, a state of matter in quantum chromodynamics
Biology
* Blood pla ...
concentrations of adrenaline also may cause cardiac arrhythmia
Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...
s (irregularities in the heart rate and rhythm), electrocardiographic changes (in 27 percent of cases) and cardiac arrest
Cardiac arrest is when the heart suddenly and unexpectedly stops beating. It is a medical emergency that, without immediate medical intervention, will result in sudden cardiac death within minutes. Cardiopulmonary resuscitation (CPR) and possib ...
(in 3 percent of cases) may occur rapidly after the onset of hemorrhage.[ A further consequence of this process is ]neurogenic
In Biology, biology, the nervous system is the Complex system, highly complex part of an animal that coordinates its Behavior, actions and Sense, sensory information by transmitting action potential, signals to and from different parts of its ...
pulmonary edema
Pulmonary edema, also known as pulmonary congestion, is excessive edema, liquid accumulation in the parenchyma, tissue and pulmonary alveolus, air spaces (usually alveoli) of the lungs. It leads to impaired gas exchange and may cause hypoxemia an ...
where a process of increased pressure within the pulmonary circulation causes leaking of fluid from the pulmonary capillaries
A capillary is a small blood vessel from 5 to 10 micrometres (μm) in diameter. Capillaries are composed of only the tunica intima, consisting of a thin wall of simple squamous endothelial cells. They are the smallest blood vessels in the body: ...
into the air spaces, the alveoli Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit.
Uses in anatomy and zoology
* Pulmonary alveolus, an air sac in the lungs
** Alveolar cell or pneumocyte
** Alveolar duct
** Alveolar macrophage
* ...
, of the lung.
Subarachnoid hemorrhage may also occur in people who have had a head injury. Symptoms may include headache, decreased level of consciousness and hemiparesis
Hemiparesis, or unilateral paresis, is weakness of one entire side of the body (''wikt:hemi-#Prefix, hemi-'' means "half"). Hemiplegia is, in its most severe form, complete paralysis of half of the body. Hemiparesis and hemiplegia can be caused ...
(weakness of one side of the body). SAH is a frequent occurrence in traumatic brain injury, and carries a poor prognosis if it is associated with deterioration in the level of consciousness.
While thunderclap headache is the characteristic symptom of subarachnoid hemorrhage, less than 10% of those with concerning symptoms have SAH on investigations.[ A number of other causes may need to be considered.]
Causes
Most cases of SAH are due to trauma
Trauma most often refers to:
* Major trauma, in physical medicine, severe physical injury caused by an external source
* Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event
*Traumatic i ...
such as a blow to the head.[ Traumatic SAH usually occurs near the site of a ]skull fracture
A skull fracture is a break in one or more of the eight bones that form the cranial portion of the human skull, skull, usually occurring as a result of blunt force trauma. If the force of the impact is excessive, the bone may fracture at or near ...
or intracerebral contusion. It often happens in the setting of other forms of traumatic brain injury. In these cases prognosis is poorer; however, it is unclear if this is a direct result of the SAH or whether the presence of subarachnoid blood is simply an indicator of a more severe head injury.
In 85 percent of spontaneous cases the cause is a cerebral aneurysm
An intracranial aneurysm, also known as a brain aneurysm, is a cerebrovascular disorder in which weakness in the wall of a cerebral artery or vein causes a localized dilation or ballooning of the blood vessel.
Aneurysms in the posterior circul ...
—a weakness in the wall of one of the arteries
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pul ...
in the brain that becomes enlarged. They tend to be located in the circle of Willis
The circle of Willis (also called Willis' circle, loop of Willis, cerebral arterial circle, and Willis polygon) is a circulatory anastomosis that supplies blood to the brain and surrounding structures in reptiles, birds and mammals, including huma ...
and its branches. While most cases are due to bleeding from small aneurysms, larger aneurysms (which are less common) are more likely to rupture.[ ]Aspirin
Aspirin, also known as acetylsalicylic acid (ASA), is a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and/or inflammation, and as an antithrombotic. Specific inflammatory conditions which aspirin is used to treat inc ...
also appears to increase the risk.
In 15–20 percent of cases of spontaneous SAH, no aneurysm is detected on the first angiogram
Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is performe ...
. About half of these are attributed to non-aneurysmal perimesencephalic hemorrhage, in which the blood is limited to the subarachnoid spaces around the midbrain
The midbrain or mesencephalon is the forward-most portion of the brainstem and is associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation. The name comes from the Greek ''mesos'', " ...
(i.e. mesencephalon). In these, the origin of the blood is uncertain.[ The remainder are due to other disorders affecting the blood vessels (such as ]cerebral arteriovenous malformation
A cerebral arteriovenous malformation (cerebral AVM, CAVM, cAVM) is an abnormal connection between the arteries and veins in the brain—specifically, an arteriovenous malformation in the cerebrum.
Signs and symptoms
The most frequently observed ...
s), disorders of the blood vessels in the spinal cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spi ...
, and bleeding into various tumor
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
s.[
]Cocaine
Cocaine (from , from , ultimately from Quechuan languages, Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly recreational drug use, used recreationally for its euphoria, euphoric effects. It is primarily obtained from t ...
abuse and sickle cell anemia
Sickle cell disease (SCD) is a group of blood disorders typically inherited from a person's parents. The most common type is known as sickle cell anaemia. It results in an abnormality in the oxygen-carrying protein haemoglobin found in red blo ...
(usually in children) and, rarely, anticoagulant
Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in blood-eating animals such as leeches and mosquitoes, where the ...
therapy, problems with blood clotting and pituitary apoplexy
Pituitary apoplexy is bleeding into or impaired blood supply of the pituitary gland. This usually occurs in the presence of a tumor of the pituitary, although in 80% of cases this has not been diagnosed previously. The most common initial sympto ...
can also result in SAH. Dissection of the vertebral artery, usually caused by trauma, can lead to subarachnoid hemorrhage if the dissection involves the part of the vessel inside the skull.
Pathophysiology
Cerebral vasospasm is one of the complications caused by subarachnoid hemorrhage. It usually happens from the third day after the aneurysm event, and reaches its peak on 5th to 7th day. There are several mechanisms proposed for this complication. Blood products released from subarachnoid hemorrhage stimulates the tyrosine kinase
A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to the tyrosine residues of specific proteins inside a cell. It functions as an "on" or "off" switch in many cellular functions.
Tyrosine kinases belong to a larger cla ...
pathway causing the release of calcium ions from intracellular storage, resulting in smooth muscle contraction of cerebral arteries. Oxyhaemoglobin
Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyte ...
in cerebrospinal fluid
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.
CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...
(CSF) causes vasoconstriction by increasing free radicals
In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron.
With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spont ...
, endothelin-1
Endothelin 1 (ET-1), also known as preproendothelin-1 (PPET1), is a potent Vasoconstriction, vasoconstrictor peptide produced by vascular endothelium, endothelial cells. The protein encoded by this gene ''EDN1'' is proteolysis, proteolytically pr ...
, prostaglandin
The prostaglandins (PG) are a group of physiologically active lipid compounds called eicosanoids having diverse hormone-like effects in animals. Prostaglandins have been found in almost every tissue in humans and other animals. They are derive ...
and reducing the level of nitric oxide
Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its che ...
and prostacyclin
Prostacyclin (also called prostaglandin I2 or PGI2) is a prostaglandin member of the eicosanoid family of lipid molecules. It inhibits platelet activation and is also an effective vasodilator.
When used as a drug, it is also known as epoprosteno ...
. Besides, the disturbances of autonomic nervous system
The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that supplies viscera, internal organs, smooth muscle and glands. The autonomic nervous system is a control ...
innervating cerebral arteries is also thought to cause vasospasm.
Diagnosis
As only 10 percent of people admitted to the emergency department with a thunderclap headache are having an SAH, other possible causes are usually considered simultaneously, such as meningitis
Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or ...
, migraine
Migraine (, ) is a common neurological disorder characterized by recurrent headaches. Typically, the associated headache affects one side of the head, is pulsating in nature, may be moderate to severe in intensity, and could last from a few hou ...
, and cerebral venous sinus thrombosis
Cerebral venous sinus thrombosis (CVST), cerebral venous and sinus thrombosis or cerebral venous thrombosis (CVT), is the presence of a blood clot in the dural venous sinuses (which drain blood from the brain), the cerebral veins, or both. Symp ...
.[ ]Intracerebral hemorrhage
Intracerebral hemorrhage (ICH), also known as cerebral bleed, intraparenchymal bleed, and hemorrhagic stroke, or haemorrhagic stroke, is a sudden bleeding into Intraparenchymal hemorrhage, the tissues of the brain, into its Intraventricular hemor ...
, in which bleeding occurs within the brain itself, is twice as common as SAH and is often misdiagnosed as the latter. It is not unusual for SAH to be initially misdiagnosed as a migraine or tension headache
Tension headache, also known as stress headache, or tension-type headache (TTH), is the most common type of primary headache. The pain can radiate from the lower back of the head, the neck, eyes or other muscle groups in the body typically affecti ...
, which can lead to a delay in obtaining a CT scan. In a 2004 study, this occurred in 12 percent of all cases and was more likely in people who had smaller hemorrhages and no impairment in their mental status. The delay in diagnosis led to a worse outcome. In some people, the headache resolves by itself, and no other symptoms are present. This type of headache is referred to as "sentinel headache", because it is presumed to result from a small leak (a "warning leak") from an aneurysm. A sentinel headache still warrants investigations with CT scan and lumbar puncture, as further bleeding may occur in the subsequent three weeks.
The initial steps for evaluating a person with a suspected subarachnoid hemorrhage are obtaining a medical history
The medical history, case history, or anamnesis (from Greek: ἀνά, ''aná'', "open", and μνήσις, ''mnesis'', "memory") of a patient is information gained by a physician by asking specific questions, either to the patient or to other peo ...
and performing a physical examination
In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the patien ...
. The diagnosis cannot be made on clinical grounds alone and in general medical imaging
Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to rev ...
and possibly a lumbar puncture is required to confirm or exclude bleeding.
Imaging
The modality of choice is computed tomography
A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...
(CT scan), without contrast, of the brain. This has a high sensitivity and will correctly identify 98.7% of cases within six hours of the onset of symptoms. A CT scan can rule out the diagnosis in someone with a normal neurological exam if done within six hours. Its efficacy declines thereafter,[ and ]magnetic resonance imaging
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...
(MRI) is more sensitive than CT after several days.[
]
Angiography
After a subarachnoid hemorrhage is confirmed, its origin needs to be determined. If the bleeding is likely to have originated from an aneurysm (as determined by the CT scan appearance), the choice is between cerebral angiography
Cerebral angiography is a form of angiography which provides images of blood vessels in and around the brain, thereby allowing detection of abnormalities such as arteriovenous malformations and aneurysms.
It was pioneered in 1927 by the Portugues ...
(injecting radiocontrast through a catheter
In medicine, a catheter (/ˈkæθətər/) is a thin tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. Cath ...
to the brain arteries) and CT angiography
Computed tomography angiography (also called CT angiography or CTA) is a computed tomography technique used for angiography—the visualization of arteries and veins—throughout the human body. Using contrast injected into the blood vessels, i ...
(visualizing blood vessel
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away ...
s with radiocontrast
Radiocontrast agents are substances used to enhance the visibility of internal structures in X-ray-based imaging techniques such as computed tomography (contrast CT), projectional radiography, and fluoroscopy. Radiocontrast agents are typically io ...
on a CT scan) to identify aneurysms. Catheter angiography also offers the possibility of coiling an aneurysm (see below).[
In emergency department patients complaining of acute-onset headache without significant risk factors for SAH, evidence suggests that CT scanning of the head followed by CT angiography can reliably exclude SAH without the need for a lumbar puncture.] The risk of missing an aneurysmal bleed as the cause of SAH with this approach is less than 1%.
Lumbar puncture
Lumbar puncture
Lumbar puncture (LP), also known as a spinal tap, is a medical procedure in which a needle is inserted into the spinal canal, most commonly to collect cerebrospinal fluid (CSF) for diagnostic testing. The main reason for a lumbar puncture is to ...
, in which cerebrospinal fluid
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.
CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...
(CSF) is removed from the subarachnoid space
In anatomy, the meninges (, ''singular:'' meninx ( or ), ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in th ...
of the spinal canal
The spinal canal (or vertebral canal or spinal cavity) is the canal that contains the spinal cord within the vertebral column. The spinal canal is formed by the vertebrae through which the spinal cord passes. It is a process of the dorsal body ca ...
using a hypodermic needle
A hypodermic needle (from Greek ὑπο- (''hypo-'' = under), and δέρμα (''derma'' = skin)), one of a category of medical tools which enter the skin, called sharps, is a very thin, hollow tube with one sharp tip. It is commonly used w ...
, shows evidence of bleeding in three percent of people in whom a non-contrast CT was found normal.[ A lumbar puncture or CT scan with contrast is therefore regarded as mandatory in people with suspected SAH when imaging is delayed to after six hours from the onset of symptoms and is negative.][ At least three tubes of CSF are collected.][ If an elevated number of ]red blood cell
Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
s is present equally in all bottles, this indicates a subarachnoid hemorrhage. If the number of cells decreases per bottle, it is more likely that it is due to damage to a small blood vessel during the procedure (known as a "traumatic tap").[ While there is no official cutoff for red blood cells in the CSF no documented cases have occurred at less than "a few hundred cells" per high-powered field.
The CSF sample is also examined for ]xanthochromia
Xanthochromia, from the Greek ''xanthos'' (ξανθός) "yellow" and ''chroma'' (χρώμα) "colour", is the yellowish appearance of cerebrospinal fluid that occurs several hours after bleeding into the subarachnoid space caused by certain medic ...
—the yellow appearance of centrifugated fluid. This can be determined by spectrophotometry
Spectrophotometry is a branch of electromagnetic spectroscopy concerned with the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. Spectrophotometry uses photometers, known as spec ...
(measuring the absorption of particular wavelengths of light) or visual examination. It is unclear which method is superior. Xanthochromia remains a reliable ways to detect SAH several days after the onset of headache.[ An interval of at least 12 hours between the onset of the headache and lumbar puncture is required, as it takes several hours for the hemoglobin from the red blood cells to be metabolized into ]bilirubin
Bilirubin (BR) (Latin for "red bile") is a red-orange compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates. This catabolism is a necessary process in the body's clearance of waste products that arise from the ...
.
ECG
Electrocardiographic
Electrocardiography is the process of producing an electrocardiogram (ECG or EKG), a recording of the heart's electrical activity. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the hear ...
changes are relatively common in subarachnoid hemorrhage, occurring in 40–70 percent of cases. They may include QT prolongation
Long QT syndrome (LQTS) is a condition affecting repolarization (relaxing) of the heart after a heartbeat, giving rise to an abnormally lengthy QT interval. It results in an increased risk of an irregular heartbeat which can result in fainting, ...
, Q waves
In elastodynamics, Love waves, named after Augustus Edward Hough Love, are horizontally polarized surface waves. The Love wave is a result of the interference of many shear waves (S-waves) guided by an elastic layer, which is ''welded'' to an ...
, cardiac dysrhythmia
Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...
s, and ST elevation
ST elevation refers to a finding on an electrocardiogram wherein the trace in the ST segment is abnormally high above the baseline.
Electrophysiology
The ST segment starts from the J point (termination of QRS complex and the beginning of ST segm ...
that mimics a heart attack
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may tr ...
.
Also one of the characteristic ECG
Electrocardiography is the process of producing an electrocardiogram (ECG or EKG), a recording of the heart's electrical activity. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the hear ...
changes that could be found in patients with subarachnoid hemorrhage, is the J wave
A J wave — also known as Osborn wave, camel-hump sign, late delta wave, hathook junction, hypothermic wave, K wave, H wave or current of injury — is an abnormal electrocardiogram finding.
J waves are positive deflections occurring at the ju ...
s or Osborn waves, which are positive deflections that occur at the junction between QRS complexes
The QRS complex is the combination of three of the graphical deflections seen on a typical electrocardiogram (ECG or EKG). It is usually the central and most visually obvious part of the tracing. It corresponds to the depolarization of the ri ...
and ST segment
In electrocardiography, the ST segment connects the QRS complex and the T wave and has a duration of 0.005 to 0.150 sec (5 to 150 ms).
It starts at the J point (junction between the QRS complex and ST segment) and ends at the beginning of the T ...
s, where the S point, also known as the J point, has a myocardial infarction-like elevation. J waves or Osborn waves, which represent an early repolarization
In neuroscience, repolarization refers to the change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential which has changed the membrane potential to a positive value. The repolarizat ...
and delayed depolarization
In biology, depolarization or hypopolarization is a change within a cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell compared to the outside. Depolarization is esse ...
of the heart ventricles, are thought to be caused by the high catecholamines
A catecholamine (; abbreviated CA) is a monoamine neurotransmitter, an organic compound that has a catechol (benzene with two hydroxyl side groups next to each other) and a side-chain amine.
Catechol can be either a free molecule or a substi ...
surge released in patients with subarachnoid hemorrhage or brain damage, the issue that might lead to ventricular fibrillation
Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the ventricles of the heart quiver. It is due to disorganized electrical activity. Ventricular fibrillation results in cardiac arrest with loss of consciousness and no p ...
and cardiac arrest
Cardiac arrest is when the heart suddenly and unexpectedly stops beating. It is a medical emergency that, without immediate medical intervention, will result in sudden cardiac death within minutes. Cardiopulmonary resuscitation (CPR) and possib ...
in unmanaged patients.
Classification
There are several grading scales available for SAH. The Glasgow Coma Scale
The Glasgow Coma Scale (GCS) is a clinical scale used to reliably measure a person's level of consciousness after a brain injury.
The GCS assesses a person based on their ability to perform eye movements, speak, and move their body. These thre ...
(GCS) is ubiquitously used for assessing consciousness. Its three specialized scores are used to evaluate SAH; in each, a higher number is associated with a worse outcome. These scales have been derived by retrospectively matching characteristics of people with their outcomes.
The first widely used scale for neurological condition following SAH was published by Harry Botterell, Botterell and Cannell in 1956 and referred to as the Botterell Grading Scale. This was modified by Hunt and Hess in 1968:
The Fisher Grade classifies the appearance of subarachnoid hemorrhage on CT scan.
This scale has been modified by Claassen and coworkers, reflecting the additive risk from SAH size and accompanying intraventricular hemorrhage (0 – none; 1 – minimal SAH w/o IVH; 2 – minimal SAH with IVH; 3 – thick SAH w/o IVH; 4 – thick SAH with IVH);.
The World Federation of Neurosurgeons (WFNS) classification uses Glasgow coma score and focal neurological deficit to gauge severity of symptoms.
A comprehensive classification scheme has been suggested by Ogilvy and Carter to predict outcome and gauge therapy. The system consists of five grades and it assigns one point for the presence or absence of each of five factors: age greater than 50; Hunt and Hess grade 4 or 5; Fisher scale 3 or 4; aneurysm size greater than 10 mm; and posterior circulation aneurysm 25 mm or more.
Screening and prevention
Screening (medicine), Screening for aneurysms is not performed on a population level; because they are relatively rare, it would not be cost-effectiveness analysis, cost-effective. However, if someone has two or more first-degree relatives who have had an aneurysmal subarachnoid hemorrhage, screening may be worthwhile.
Polycystic kidney disease#Autosomal dominant form, Autosomal dominant polycystic kidney disease (ADPKD), a hereditary kidney condition, is known to be associated with cerebral aneurysms in 8 percent of cases, but most such aneurysms are small and therefore unlikely to rupture. As a result, screening is only recommended in families with ADPKD where one family member has had a ruptured aneurysm.
An aneurysm may be detected incidentally on brain imaging; this presents a conundrum, as all treatments for cerebral aneurysms are associated with potential complications. The International Study of Unruptured Intracranial Aneurysms (ISUIA) provided prognostic data both in people having previously had a subarachnoid hemorrhage and people who had aneurysms detected by other means. Those having previously had a SAH were more likely to bleed from other aneurysms. In contrast, those having never bled and had small aneurysms (smaller than 10 mm) were very unlikely to have a SAH and were likely to sustain harm from attempts to repair these aneurysms.[ On the basis of the ISUIA and other studies, it is now recommended that people are considered for preventive healthcare, preventive treatment only if they have a reasonable life expectancy and have aneurysms that are highly likely to rupture.][ Moreover, there is only limited evidence that endovascular treatment of unruptured aneurysms is actually beneficial.
]
Treatment
Management involves general measures to stabilize the person while also using specific investigations and treatments. These include the prevention of rebleeding by obliterating the bleeding source, prevention of a phenomenon known as vasospasm, and prevention and treatment of complications.[
Stabilizing the person is the first priority. Those with a depressed level of consciousness may need to be intubation, intubated and mechanical ventilation, mechanically ventilated. Blood pressure, pulse, respiratory rate, and Glasgow Coma Scale are monitored frequently. Once the diagnosis is confirmed, admission to an intensive care unit may be preferable, especially since 15 percent may have further bleeding soon after admission. Nutrition is an early priority, mouth or nasogastric intubation, nasogastric tube feeding being preferable over parenteral nutrition, parenteral routes. In general, pain control is restricted to less-sedating agents such as codeine, as sedation may impact on the mental status and thus interfere with the ability to monitor the level of consciousness. Deep vein thrombosis is prevented with compression stockings, intermittent pneumatic compression of the calf (anatomy), calves, or both.][ A urinary catheterization, bladder catheter is usually inserted to monitor fluid balance. Benzodiazepines may be administered to help relieve distress.][ Antiemetic drugs should be given to awake persons.]
People with poor clinical grade on admission, acute neurologic deterioration, or progressive enlargement of ventricles on CT scan are, in general, indications for the placement of an external ventricular drain by a neurosurgeon. The external ventricular drain may be inserted at the bedside or in the operating room. In either case, strict aseptic technique must be maintained during insertion. In people with aneurysmal subarachnoid hemorrhage the EVD is used to remove cerebrospinal fluid
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.
CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...
, blood, and blood byproducts that increase intracranial pressure
Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury (mmHg) and at rest, is normally 7–15 Millimeter of mercury, mmHg ...
and may increase the risk for cerebral vasospasm.
Preventing rebleeding
Efforts to keep a person's systolic blood pressure somewhere between 140 and 160 mmHg is generally recommended.[ Medications to achieve this may include ]labetalol
Labetalol is a medication used to treat high blood pressure and in long term management of angina. This includes essential hypertension, hypertensive emergencies, and hypertension of pregnancy. In essential hypertension it is generally less pr ...
or nicardipine.[
People whose CT scan shows a large hematoma, depressed level of consciousness, or focal neurologic signs may benefit from urgent surgical removal of the blood or occlusion of the bleeding site. The remainder are stabilized more extensively and undergo a cerebral angiography, transfemoral angiogram or CT angiogram later. It is hard to predict who will have a rebleed, yet it may happen at any time and carries a dismal prognosis. After the first 24 hours have passed, rebleeding risk remains around 40 percent over the subsequent four weeks, suggesting that interventions should be aimed at reducing this risk as soon as possible.][ Some predictors of early rebleeding are high systolic blood pressure, the presence of a hematoma in the brain or ventricles, poor Hunt-Hess grade (III-IV), aneurysms in the posterior circulation, and an aneurysm >10 mm in size.
If a ]cerebral aneurysm
An intracranial aneurysm, also known as a brain aneurysm, is a cerebrovascular disorder in which weakness in the wall of a cerebral artery or vein causes a localized dilation or ballooning of the blood vessel.
Aneurysms in the posterior circul ...
is identified on angiography, two measures are available to reduce the risk of further bleeding from the same aneurysm: clipping (medicine), clipping and Guglielmi Detachable Coil, coiling. Clipping requires a craniotomy (opening of the skull) to locate the aneurysm, followed by the placement of clips around the neck of the aneurysm. Coiling is performed through the large blood vessels (endovascularly): a catheter is inserted into the femoral artery in the groin and advanced through the aorta to the arteries (both carotid artery, carotid arteries and both vertebral artery, vertebral arteries) that supply the brain. When the aneurysm has been located, platinum coils are deployed that cause a thrombosis, blood clot to form in the aneurysm, obliterating it. The decision as to which treatment is undertaken is typically made by a multidisciplinary team consisting of a neurosurgery, neurosurgeon, neuroradiology, neuroradiologist, and often other health professionals.[
In general, the decision between clipping and coiling is made on the basis of the location of the aneurysm, its size and the condition of the person. Aneurysms of the middle cerebral artery and its related vessels are hard to reach with angiography and tend to be amenable to clipping. Those of the basilar artery and posterior cerebral artery are hard to reach surgically and are more accessible for endovascular management.] These approaches are based on general experience, and the only randomized controlled trial directly comparing the different modalities was performed in relatively well people with small (less than 10 mm) aneurysms of the anterior cerebral artery and anterior communicating artery (together the "anterior circulation"), who constitute about 20 percent of all people with aneurysmal SAH.[ This trial, the ''International Subarachnoid Aneurysm Trial'' (ISAT), showed that in this group the likelihood of death or being dependent on others for activities of daily living was reduced (7.4 percent absolute risk reduction, 23.5 percent relative risk reduction) if endovascular coiling was used as opposed to surgery.][ The main drawback of coiling is the possibility that the aneurysm will recur; this risk is extremely small in the surgical approach. In ISAT, 8.3 percent needed further treatment in the longer term. Hence, people who have undergone coiling are typically followed up for many years afterwards with angiography or other measures to ensure recurrence of aneurysms is identified early. Other trials have also found a higher rate of recurrence necessitating further treatments.
]
Vasospasm
Vasospasm, in which the blood vessels constrict and thus restrict blood flow, is a serious complication of SAH. It can cause ischemia, ischemic acquired brain injury, brain injury (referred to as "delayed ischemia") and permanent brain damage due to lack of oxygen in parts of the brain.[ It can be fatal if severe. Delayed ischemia is characterized by new neurological symptoms, and can be confirmed by transcranial doppler or cerebral angiography. About one third of people admitted with subarachnoid hemorrhage will have delayed ischemia, and half of those have permanent damage as a result.] It is possible to screen for the development of vasospasm with transcranial Doppler every 24–48 hours. A blood flow velocity of more than 120 metre per second, centimeters per second is suggestive of vasospasm.[
The pathogenesis of cerebral vasospasm following subarachnoid hemorrhage is attributed to the higher levels of endothelin 1, a potent vasoconstrictor, and the lower levels of endothelial NOS (eNOS), a potent vasodilator. Both of which are produced from a series of events that begin from the inflammatory reaction caused by the products released from erythrocytes' degradation. Following subarachnoid hemorrhage, different clotting factors and blood products are released into the surrounding perivascular spaces known as (Virchow-Robin spaces). The released clotting factors like; fibrinopeptides, thromboxane A2 and others lead to microthrombosis around near vessels that leads to extrinsic vasoconstriction of these vessels. Besides that extrinsic vasoconstriction, the erythrocytes' degradation products like; ]bilirubin
Bilirubin (BR) (Latin for "red bile") is a red-orange compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates. This catabolism is a necessary process in the body's clearance of waste products that arise from the ...
and oxyhemoglobin lead to neuroinflammation that in turn increases the production of reactive oxygen species (ROS) which increases and decreases the production of endothelin 1 and endothelial NOS, respectively, the issue that yields in intrinsic vasoconstriction of the neighboring blood vessels and results in cerebral ischemia if left untreated.
The use of calcium channel blocker
Calcium channel blockers (CCB), calcium channel antagonists or calcium antagonists are a group of medications that disrupt the movement of calcium () through calcium channels. Calcium channel blockers are used as antihypertensive drugs, i.e., as ...
s, thought to be able to prevent the spasm of blood vessels by preventing calcium from entering smooth muscle cells, has been proposed for prevention. The calcium channel blocker nimodipine when taken by mouth improves outcome if given between the fourth and twenty-first day after the bleeding, even if it does not reduce the amount of vasospasm detected on angiography. It is the only Food and Drug Administration (FDA)-approved drug for treating cerebral vasospasm. In ''traumatic'' subarachnoid hemorrhage, nimodipine does not affect long-term outcome, and is not recommended. Other calcium channel blockers and magnesium sulfate have been studied, but are not presently recommended; neither is there any evidence that shows benefit if nimodipine is given intravenously.[
Nimodipine is readily authorized in the form of tablets and solution for infusion for the prevention and treatment of complications due to vasospasm following subarachnoid hemorrhage. Another sustained formulation of nimodipine administered via an external ventricular drain (EVD), called EG-1962, is also available. In contrast to the tablets and solution formulations of Nimodipine which require an administration every 4hrs for a total of 21 days, the sustained formulation, EG-1962, needs to be administered once directly into the ventricles. The CSF concentrations from EG-1962, however, were at least 2 orders of magnitude higher than those with oral nimodipine. These results supported a phase 3 study that demonstrated a favorable safety profile for EG-1962 but yielded inconclusive efficacy results due to notable differences in clinical outcome based on baseline disease severity.
Some older studies have suggested that statin therapy might reduce vasospasm, but a subsequent meta-analysis including further trials did not demonstrate benefit on either vasospasm or outcomes. While corticosteroids with mineralocorticoid activity may help prevent vasospasm their use does not appear to change outcomes.
A protocol referred to as "triple H" is often used as a measure to treat vasospasm when it causes symptoms; this is the use of intravenous fluids to achieve a state of hypertension (high blood pressure), hypervolemia (excess fluid in the circulation), and hemodilution (mild dilution of the blood).] Evidence for this approach is inconclusive; no randomized controlled trials have been undertaken to demonstrate its effect.
If the symptoms of delayed ischemia do not improve with medical treatment, angiography may be attempted to identify the sites of vasospasms and administer vasodilator medication (drugs that relax the blood vessel wall) directly into the artery. Angioplasty (opening the constricted area with a balloon) may also be performed.[
]
Other complications
Hydrocephalus (obstruction of the flow of cerebrospinal fluid) may complicate SAH in both the short and long term. It is detected on CT scanning, on which there is enlargement of the lateral ventricles. If the level of consciousness is decreased, drainage of the excess fluid is performed by therapeutic lumbar puncture, extraventricular drain (a temporary device inserted into one of the ventricles), or occasionally a permanent cerebral shunt, shunt.[ Relief of hydrocephalus can lead to an enormous improvement in a person's condition.][ Fluctuations in blood pressure and electrolyte imbalance, as well as pneumonia and left ventricular failure, cardiac decompensation occur in about half the hospitalized persons with SAH and may worsen prognosis.][ Seizures occur during the hospital stay in about a third of cases.][
People have often been treated with prophylaxis, preventative antiepileptic drugs, antiepileptic medications.] This is controversial and not evidence-based medicine, based on good evidence. In some studies, use of these medications was associated with a worse prognosis; although it is unclear whether this might be because the drugs themselves actually cause harm, or because they are used more often in persons with a poorer prognosis. There is a possibility of a gastric hemorrhage due to stress ulcers.
Prognosis
Short-term outcomes
SAH is often associated with a poor outcome. The death rate (mortality rate, mortality) for SAH is between 40 and 50 percent, but trends for survival are improving.[ Of those that survive hospitalization, more than a quarter have significant restrictions in their lifestyle, and less than a fifth have no residual symptoms whatsoever.][ Delay in diagnosis of minor SAH (mistaking the sudden headache for migraine) contributes to poor outcome.][ Factors found on admission that are associated with poorer outcome include poorer neurological grade; systolic hypertension; a previous diagnosis of myocardial infarction, heart attack or SAH; liver disease; more blood and larger aneurysm on the initial CT scan; location of an aneurysm in the posterior (anatomy), posterior circle of Willis, circulation; and higher age.] Factors that carry a worse prognosis during the hospital stay include occurrence of delayed ischemia resulting from vasospasm, development of intracerebral hematoma, or intraventricular hemorrhage (bleeding into the ventricular system, ventricles of the brain) and presence of fever
Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...
on the eighth day of admission.
So-called "angiogram-negative subarachnoid hemorrhage", SAH that does not show an aneurysm with four-vessel angiography, carries a better prognosis than SAH with aneurysm, but it is still associated with a risk of ischemia, rebleeding, and hydrocephalus. Perimesencephalic SAH (bleeding around the mesencephalon in the brain), however, has a very low rate of rebleeding or delayed ischemia, and the prognosis of this subtype is excellent.
The prognosis of head trauma is thought to be influenced in part by the location and amount of subarachnoid bleeding. It is difficult to isolate the effects of SAH from those of other aspects of traumatic brain injury; it is unknown whether the presence of subarachnoid blood actually worsens the prognosis or whether it is merely a sign that a significant trauma has occurred. People with moderate and severe traumatic brain injury who have SAH when admitted to a hospital have as much as twice the risk of dying as those who do not. They also have a higher risk of severe disability and persistent vegetative state, and traumatic SAH has been correlated with other markers of poor outcome such as post traumatic epilepsy, hydrocephalus, and longer stays in the intensive care unit. More than 90 percent of people with traumatic subarachnoid bleeding and a Glasgow Coma Score over 12 have a good outcome.
There is also modest evidence that genetic factors influence the prognosis in SAH. For example, having two copies of ApoE4 (a variant of the gene encoding apolipoprotein E that also plays a role in Alzheimer's disease) seems to increase risk for delayed ischemia and a worse outcome. The occurrence of hyperglycemia (high blood sugars) after an episode of SAH confers a higher risk of poor outcome.
Long-term outcomes
Neurocognitive symptoms, such as fatigue (medical), fatigue, mood disturbances, and other related symptoms, are common sequelae. Even in those who have made good neurological recovery, anxiety, depression, posttraumatic stress disorder, and cognitive impairment are common; 46 percent of people who have had a subarachnoid hemorrhage have cognitive impairment that affects their quality of life.[ Over 60 percent report frequent headaches. Aneurysmal subarachnoid hemorrhage may lead to damage of the hypothalamus and the pituitary gland, two areas of the brain that play a central role in hormonal regulation and production. More than a quarter of people with a previous SAH may develop hypopituitarism (deficiencies in one or more of the Hypothalamic–pituitary hormone, hypothalamic–pituitary hormones such as growth hormone, luteinizing hormone, or follicle-stimulating hormone). SAH is also associated with SIADH and cerebral salt wasting, and is the most common cause of the latter.
]
Epidemiology
According to a review of 51 studies from 21 countries, the average incidence (epidemiology), incidence of subarachnoid hemorrhage is 9.1 per 100,000 annually. Studies from Japan and Finland show higher rates in those countries (22.7 and 19.7, respectively), for reasons that are not entirely understood. South and Central America, in contrast, have a rate of 4.2 per 100,000 on average.
Although the group of people at risk for SAH is younger than the population usually affected by stroke,[ the risk still increases with age. Young people are much less likely than middle-age people (risk ratio 0.1, or 10 percent) to have a subarachnoid hemorrhage.][ The risk continues to rise with age and is 60 percent higher in the very elderly (over 85) than in those between 45 and 55.][ Risk of SAH is about 25 percent higher in women over 55 compared to men the same age, probably reflecting the hormonal changes that result from the menopause, such as a decrease in estrogen levels.][
Genetics may play a role in a person's disposition to SAH; risk is increased three- to fivefold in first-degree relatives of people having had a subarachnoid hemorrhage.][ But lifestyle factors are more important in determining overall risk.][ These risk factors are tobacco smoking, smoking, hypertension (high blood pressure), and excessive alcohol consumption.] Having smoked in the past confers a doubled risk of SAH compared to those who have never smoked.[ Some protection of uncertain significance is conferred by caucasian race, caucasian ethnicity, hormone therapy, hormone replacement therapy, and diabetes mellitus.][ There is likely an inverse relationship between total serum cholesterol and the risk of non-traumatic SAH, though confirmation of this association is hindered by a lack of studies.] Approximately 4 percent of aneurysmal bleeds occur after sexual intercourse and 10 percent of people with SAH are bending over or lifting heavy objects at the onset of their symptoms.[
Overall, about 1 percent of all people have one or more cerebral aneurysms. Most of these are small and unlikely to rupture.]
History
While the clinical picture of subarachnoid hemorrhage may have been recognized by Hippocrates, the existence of cerebral aneurysms and the fact that they could rupture was not established until the 18th century. The associated symptoms were described in more detail in 1886 by Edinburgh physician Dr Byrom Bramwell. In 1924, London neurologist Sir Charles Symonds, Charles P. Symonds (1890–1978) gave a complete account of all major symptoms of subarachnoid hemorrhage, and he coined the term "spontaneous subarachnoid hemorrhage".[ Symonds also described the use of ]lumbar puncture
Lumbar puncture (LP), also known as a spinal tap, is a medical procedure in which a needle is inserted into the spinal canal, most commonly to collect cerebrospinal fluid (CSF) for diagnostic testing. The main reason for a lumbar puncture is to ...
and xanthochromia
Xanthochromia, from the Greek ''xanthos'' (ξανθός) "yellow" and ''chroma'' (χρώμα) "colour", is the yellowish appearance of cerebrospinal fluid that occurs several hours after bleeding into the subarachnoid space caused by certain medic ...
in diagnosis.
The first surgical intervention was performed by Norman Dott, who was a pupil of Harvey Cushing then working in Edinburgh. He introduced the wrapping of aneurysms in the 1930s, and was an early pioneer in the use of angiograms.[ American neurosurgeon Dr Walter Dandy, working in Baltimore, was the first to introduce clips in 1938.][ Microsurgery was applied to aneurysm treatment in 1972 in order to further improve outcomes. The 1980s saw the introduction of triple H therapy][ as a treatment for delayed ischemia due to vasospasm, and trials with nimodipine][ in an attempt to prevent this complication. In 1983, the Russian neurosurgeon Zubkov and colleagues reported the first use of transluminal balloon angioplasty for vasospasm after aneurysmal SAH.] The Italian neurosurgeon Dr Guido Guglielmi introduced his endovascular coil treatment in 1991.[
]
References
External links
{{DEFAULTSORT:Subarachnoid Hemorrhage
Central nervous system disorders
Cerebrovascular diseases
Disorders causing seizures
Intensive care medicine
Neurosurgery
Neurotrauma
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