Intracranial hemorrhage (ICH) refers to any form of

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, urethr ...

within the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

. It can result from trauma, vascular abnormalities, hypertension, or other medical conditions. ICH is broadly categorized into several subtypes based on the location of the bleed:

intracerebral hemorrhage Intracerebral hemorrhage (ICH), also known as hemorrhagic stroke, is a sudden bleeding into Intraparenchymal hemorrhage, the tissues of the brain (i.e. the parenchyma), into its Intraventricular hemorrhage, ventricles, or into both. An ICH is ...

(including intraparenchymal and intraventricular hemorrhages),

subarachnoid hemorrhage Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space—the area between the arachnoid (brain), arachnoid membrane and the pia mater surrounding the human brain, brain. Symptoms may include a thunderclap headache, severe heada ...

, epidural hemorrhage, and subdural hematoma. Each subtype has distinct causes, clinical features, and treatment approaches.

Epidemiology

Acute, spontaneous intracranial hemorrhage (ICH) is the second most common form of

stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

, affecting approximately 2 million people worldwide each year. In the United States, intracranial hemorrhage accounts for about 20% of all cerebrovascular accidents, with an incidence of approximately 20 cases per 100,000 people annually. Intracranial hemorrhages is diagnosed more frequently in men and individuals over the age of 55, with incidence increasing with age. In low-income countries, the risk is higher, potentially due to reduced access to healthcare and limited education about primary prevention.

Risk factors and causes

Intracranial hemorrhage (ICH) may be classified as either traumatic or non-traumatic (spontaneous). Traumatic causes include head trauma resulting from falls, vehicular accidents, or physical assault. Non-traumatic causes are more varied and often related to underlying conditions. Chronic

hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...

is the most common non-traumatic cause, particularly in deep brain structures such as the

basal ganglia The basal ganglia (BG) or basal nuclei are a group of subcortical Nucleus (neuroanatomy), nuclei found in the brains of vertebrates. In humans and other primates, differences exist, primarily in the division of the globus pallidus into externa ...

thalamus The thalamus (: thalami; from Greek language, Greek Wikt:θάλαμος, θάλαμος, "chamber") is a large mass of gray matter on the lateral wall of the third ventricle forming the wikt:dorsal, dorsal part of the diencephalon (a division of ...

pons The pons (from Latin , "bridge") is part of the brainstem that in humans and other mammals, lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum. The pons is also called the pons Varolii ("bridge of ...

, and posterior fossa. Other spontaneous causes include

cerebral amyloid angiopathy Cerebral amyloid angiopathy (CAA) is a form of angiopathy in which amyloid beta peptide deposits in the walls of small to medium blood vessels of the central nervous system and meninges. The term ''congophilic'' is sometimes used because the pres ...

, especially among the elderly, as well as bleeding disorders such as

hemophilia Haemophilia (British English), or hemophilia (American English) (), is a mostly inherited genetic disorder that impairs the body's ability to make blood clots, a process needed to stop bleeding. This results in people bleeding for a long ...

and

thrombocytopenia In hematology, thrombocytopenia is a condition characterized by abnormally low levels of platelets (also known as thrombocytes) in the blood. Low levels of platelets in turn may lead to prolonged or excessive bleeding. It is the most common coag ...

, vascular malformations like

arteriovenous malformation An arteriovenous malformation (AVM) is an abnormal connection between arteries and veins, bypassing the capillary system. Usually congenital, this vascular anomaly is widely known because of its occurrence in the central nervous system (usually ...

(AVMs), and

brain tumor A brain tumor (sometimes referred to as brain cancer) occurs when a group of cells within the Human brain, brain turn cancerous and grow out of control, creating a mass. There are two main types of tumors: malignant (cancerous) tumors and benign ...

s. The use of

anticoagulant An anticoagulant, commonly known as a blood thinner, is a chemical substance that prevents or reduces the coagulation of blood, prolonging the clotting time. Some occur naturally in blood-eating animals, such as leeches and mosquitoes, which ...

or antiplatelet medications, such as

warfarin Warfarin, sold under the brand name Coumadin among others. It is used as an anticoagulant, anticoagulant medication. It is commonly used to prevent deep vein thrombosis and pulmonary embolism, and to protect against stroke in people who ha ...

and

aspirin Aspirin () is the genericized trademark for acetylsalicylic acid (ASA), a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and inflammation, and as an antithrombotic. Specific inflammatory conditions that aspirin is ...

, has been associated with increased hematoma volume and expansion. Illicit drug use, particularly cocaine and methamphetamine, can cause abrupt spikes in blood pressure leading to vessel rupture and subsequent hemorrhage. Additional risk factors that increase the likelihood of intracranial hemorrhage include smoking, heavy alcohol consumption, advanced age, a family history of stroke, diabetes,

hyperlipidemia Hyperlipidemia is abnormally high levels of any or all lipids (e.g. fats, triglycerides, cholesterol, phospholipids) or lipoproteins in the blood. citing: and The term ''hyperlipidemia'' refers to the laboratory finding itself and is also use ...

, obesity, and sedentary lifestyle.

Hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...

remains the most prevalent and well-established risk factor, contributing to over 60% of primary bleeds.

Signs and symptoms

Intracranial hemorrhage is a dynamic and potentially life-threatening process that begins with blood extravasation into the brain

parenchyma upright=1.6, Lung parenchyma showing damage due to large subpleural bullae. Parenchyma () is the bulk of functional substance in an animal organ such as the brain or lungs, or a structure such as a tumour. In zoology, it is the tissue that ...

. This can be followed by bleeding extension, cerebral edema formation, and increased

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 mmHg for a supine adu ...

(ICP), all of which can lead to neural tissue compression. Common signs and symptoms include a sudden onset of focal neurological deficits, which vary depending on the location of the hemorrhage. Decreased levels of

consciousness Consciousness, at its simplest, is awareness of a state or object, either internal to oneself or in one's external environment. However, its nature has led to millennia of analyses, explanations, and debate among philosophers, scientists, an ...

are frequently observed and are assessed using the Glasgow Coma Scale (GCS). Other manifestations include headache, nausea, vomiting, and seizures. Patients may also present with speech disturbances, unilateral weakness or

paralysis Paralysis (: paralyses; also known as plegia) is a loss of Motor skill, motor function in one or more Skeletal muscle, muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory d ...

, sensory deficits, visual impairments, and problems with coordination or balance. Raised diastolic blood pressure is a common clinical finding.

Seizure A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, o ...

s occur in up to 70% of causes, usually within the first 24 to 72 hours following hemorrhage onset. If bleeding extends into the ventricles,

hydrocephalus Hydrocephalus is a condition in which cerebrospinal fluid (CSF) builds up within the brain, which can cause pressure to increase in the skull. Symptoms may vary according to age. Headaches and double vision are common. Elderly adults with n ...

may develop. Brainstem hemorrhages are especially dangerous and can result in cardiorespiratory instability, decreased consciousness, and even

cardiac arrest Cardiac arrest (also known as sudden cardiac arrest CA is when the heart suddenly and unexpectedly stops beating. When the heart stops beating, blood cannot properly Circulatory system, circulate around the body and the blood flow to the ...

. Long-term complications of intracranial hemorrhages may include post-stroke

epilepsy Epilepsy is a group of Non-communicable disease, non-communicable Neurological disorder, neurological disorders characterized by a tendency for recurrent, unprovoked Seizure, seizures. A seizure is a sudden burst of abnormal electrical activit ...

and vascular cognitive impairment.

Diagnosis

A non-contrast CT scan (

computed tomography A computed tomography scan (CT scan), formerly called computed axial tomography scan (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 or ...

) of the brain is commonly used as the initial imaging modality in suspected cases of intracranial hemorrhage. CT is preferred in emergency settings due to its speed, availability, and high sensitivity for detecting acute brain injuries, enabling rapid triage and surgical decision-making. Examples of brain diseases that require urgent intervention are: large-volume hemorrhage,

brain herniation Brain herniation is a potentially deadly side effect of very high pressure within the skull that occurs when a part of the human brain, brain is squeezed across structures within the human skull, skull. The brain can shift across such structures ...

, and

cerebral infarction Cerebral infarction, also known as an ischemic stroke, is the pathologic process that results in an area of necrotic tissue in the brain (cerebral infarct). In mid to high income countries, a stroke is the main reason for disability among peo ...

. Additional advantages of CT imaging include its effectiveness in detecting bony fractures, vascular injuries, and

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless Extracellular fluid#Transcellular fluid, transcellular body fluid found within the meninges, meningeal tissue that surrounds the vertebrate brain and spinal cord, and in the ventricular system, ven ...

(CSF) leaks. Despite its advantages, MRI (

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...

) has higher sensitivity than CT scan for the detection of epidural hemorrhage, subdural hemorrhage, subarachnoid hemorrhage, non hemorrhagic contusions in the

cortex Cortex or cortical may refer to: Biology * Cortex (anatomy), the outermost layer of an organ ** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain'' *** Motor cortex, the regions of the cerebral cortex i ...

, hemorrhagic

parenchymal upright=1.6, Lung parenchyma showing damage due to large subpleural bullae. Parenchyma () is the bulk of functional substance in an animal organ such as the brain or lungs, or a structure such as a tumour. In zoology, it is the tissue that ...

contusions, brainstem injuries, and white matter axonal injuries. MRI is typically used when a patient continues to display neurological symptoms despite a normal CT scan. However, the use of MRI is limited by safety concerns regarding metallic foreign bodies, longer imaging times, and higher sensitivity to motion, reducing availability, and increased cost. A swirl sign on CT imaging— representing areas of low density with surrounding areas of high density— suggest active intracranial bleeding. The presence of this sign is associated with an increase in risk of death within one month and a poor functional prognosis at three months among survivors.

Traumatic

Intracranial hemorrhages are broadly classified into ''intra-axial'' and ''extra-axial'' types, based on the location of the bleeding relative to the brain tissue. Intra-axial hemorrhage refers to bleeding that occurs within the brain parenchyma or ventricular system. This category includes ''intraparenchymal hemorrhage'', which involves bleeding directly into the brain tissue, and ''intraventricular hemorrhage'', which involves bleeding into the brain’s ventricular system—commonly observed in premature infants. Intra-axial hemorrhages are generally associated with a poorer prognosis and are more challenging to manage than extra-axial hemorrhages. Traumatic forms of intra-axial hemorrhage include ''hemorrhagic parenchymal contusions'' and ''cerebral microhemorrhages.'' Extra-axial hemorrhage occurs within the cranial vault but outside the brain tissue. It encompasses three main subtypes: ''epidural hematoma'', ''subdural hematoma'', and ''subarachnoid hemorrhage'', each defined by the specific meningeal compartment in which the bleeding occurs.

Hemorrhagic parenchymal contusion

Hemorrhagic parenchymal contusions most commonly occur following significant head trauma, particularly in cases involving rapid head movement or direct impact. These injuries result from the disruption of small

arterial An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...

venous Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and fetal c ...

vessels, leading to hemorrhage within the brain

. On computed tomography (CT), they appear as hyperdense lesions. Magnetic resonance imaging (MRI), particularly with gradient echo sequences, is more sensitive than CT in detecting small hemorrhagic contusions. Contusions are frequently observed in areas of the brain adjacent to the base of the skull, such as the inferior frontal lobess and

temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain. The temporal lobe is involved in pr ...

s, commonly resulting from '' coup-contrecoup'' injuries. Those with parenchymal contusion require frequent follow-up imaging because such contusions may grow large enough to become hemorrhage and exert a significant mass effect on the brain.

Cerebral microhemorrhage

Cerebral microhemorrhages are small-scale hemorrhagic lesions that can be considered a minor form of hemorrhagic parenchymal contusion. They are typically located within the cerebral white matter and are challenging to detect using CT imaging. However, they are more readily identified on MRI, particularly with gradient echo or susceptibility-weighted imaging (SWI), where they appear as hypointense foci due to susceptibility blooming artifacts. Such microhemorrhages are frequently associated with diffuse axonal injury and located near the

grey Grey (more frequent in British English) or gray (more frequent in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning that it has no chroma. It is the color of a cloud-covered s ...

–white matter junction.

Epidural hemorrhage

Epidural hemorrhage (also known as extradural hemorrhage, EDH) refers to bleeding between the dura mater and the inner surface of the skull, typically resulting from traumatic head injury. This condition is characterized by its inability to cross cranial suture lines due to the tight adhesion of the dura to the skull at these points. However, in rare cases—especially in children where skull sutures are not fully fused—epidural hemorrhages may extend across sutures if a fracture involves them. On computed tomography (CT), epidural hemorrhages typically appear as ''biconvex'' (lentiform) hyperdense lesions confined by sutural boundaries. The source of bleeding may be arterial or venous. Arterial injuries, such as to the middle meninges artery, commonly at the

pterion The pterion is the region where the frontal, parietal, temporal, and sphenoid bones join. It is located on the side of the skull, just behind the temple. It is also considered to be the weakest part of the skull, which makes it clinically si ...

, lead to rapidly expanding hematomas. Venous sources are usually slower-growing and may involve

dural venous sinuses The dural venous sinuses (also called dural sinuses, cerebral sinuses, or cranial sinuses) are venous sinuses (channels) found between the periosteal and meningeal layers of dura mater in the brain. They receive blood from the cerebral veins, ...

, including the falx cerebri,

tentorium cerebelli The cerebellar tentorium or tentorium cerebelli (Latin for "tent of the cerebellum") is one of four dural folds that separate the cranial cavity into four (incomplete) compartments. The cerebellar tentorium separates the cerebellum from the cere ...

, or the

superior sagittal sinus The superior sagittal sinus (also known as the superior longitudinal sinus), within the human head, is an unpaired dural venous sinus lying along the attached margin of the falx cerebri. It allows blood to drain from the lateral aspects of the a ...

. Anterior temporal EDH is usually caused by sphenoparietal sinus. Such EDH is limited and does not require surgery because its extension is confined within the sphenosquamosal suture and the superior or

inferior orbital fissure The inferior orbital fissure is a gap between the Greater wing of sphenoid bone, greater wing of sphenoid bone, and the maxilla. It connects the Orbit (anatomy), orbit (anteriorly) with the infratemporal fossa and pterygopalatine fossa (posterio ...

s. In 20% to 50% of epidural hemorrhage cases, there is a lucid interval during which the patient regains temporary consciousness after an initial loss; this is then followed by deterioration of conscious state. When the epidural hematoma is large enough, it will cause mass effect on contralateral brain which lead to midline, subfalcine (below the falx cerebri), and trans-tentorial (crossing tentorium cerebelli) herniations. This phenomenon can cause the subject to lose consciousness and eventually death. Large EDH often requires emergent surgical clot evacuation. Embolisation of middle meningeal artery is performed if the hemorrhage is medium or small.

Subdural hemorrhage

Subdural hemorrhage (SDH) results from tearing of the bridging veins in the

subdural space The subdural space (or subdural cavity) is a potential space that can be opened by the separation of the arachnoid mater from the dura mater as the result of trauma, pathologic process, or the absence of cerebrospinal fluid as seen in a cadaver. ...

between the dura and

arachnoid mater 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 ...

. It can cross the suture lines, but not across dural reflections such as falx cerebri or tentorium cerebelli. Therefore, subdural hematoma are typically confined to one side of the

cerebral hemisphere The vertebrate cerebrum (brain) is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres ...

. Density of SDH reduces as it progresses from acute to chronic forms. However, areas with low density may not represent chronic SDH entirely as unclotted blood products that are due to active bleed can also give low density appearance on CT scans especially those with

coagulopathy Coagulopathy (also called a bleeding disorder) is a condition in which the blood's ability to coagulate (form clots) is impaired. This condition can cause a tendency toward prolonged or excessive bleeding ( bleeding diathesis), which may occur s ...

. Those with SDH that have same density with brain parenchyma may represent acute bleed such as those with

anemia Anemia (also spelt anaemia in British English) is a blood disorder in which the blood has a reduced ability to carry oxygen. This can be due to a lower than normal number of red blood cells, a reduction in the amount of hemoglobin availabl ...

, arachnoid tear, and the mixing of hemorrhage and CSF. SDH usually have high or mixed densities during first two days of trauma, followed by isodensity at 11 days after trauma, and hypodensity after 14 days of trauma. Membranes with

granulation tissue Granulation tissue is new connective tissue and microscopic blood vessels that form on the surfaces of a wound during the healing process. Granulation tissue typically grows from the base of a wound and is able to fill wounds of almost any size ...

can rupture within SDH, and give high density appearance on CT scan. Over a prolonged period of time, calcifications can form. SDH can be treated with burr hole drainage,

craniotomy A craniotomy is a surgery, surgical operation in which a bone flap is temporarily removed from the Human skull, skull to access the Human brain, brain. Craniotomies are often critical operations, performed on patients who are suffering from brain ...

or port system placement for blood clot evacuation, or middle meningeal artery embolisation. Subdural hematoma maybe less acute than epidural hematoma due to slower blood accumulation, but it still has the potential to cause brain herniation that may require surgical evacuation. Clinical features depend on the location and severity of the injury. Patients may have a history of loss of consciousness but they recover and do not relapse. Symptoms vary but may include loss of consciousness, seizures, or focal neurologic deficits, with an onset that can be delayed by hours to days after injury.

Subarachnoid hemorrhage

A ''subarachnoid hemorrhage'' (SAH) is

into the subarachnoid space—the area between the arachnoid membrane and the

pia mater Pia mater ( or ),Entry "pia mater"
in
brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

. Trauma can also cause SAH when the arteries and veins coursing through the subarachnoid space are ruptured. On CT imaging, traumatic SAH is usually localized to the cerebral sulci near the vertex of the head and typically spares the basal cisterns. Severe trauma can cause SAH in all regions of the brain. When the SAH volume is large, rarely it can cause cerebral infarction a few days after trauma due to arterial vasospasm. Although CT scans are more frequently used for initial evaluation, MRI is more sensitive than CT in detecting SAH. Findings may include hyperintense signal of

fluid-attenuated inversion recovery Fluid-attenuated inversion recovery (FLAIR) is a MRI sequence, magnetic resonance imaging sequence with an inversion recovery set to null fluids. For example, it can be used in brain imaging to suppress cerebrospinal fluid (CSF) effects on the im ...

(FLAIR) sequence and blooming artifact on susceptibility weighted imaging (SWI). Further vascular imaging, such as CT angiography (CTA) or

MR angiography Magnetic resonance angiography (MRA) is a group of techniques based on magnetic resonance imaging (MRI) to image blood vessels. Magnetic resonance angiography is used to generate images of arteries (and less commonly veins) in order to evaluate ...

(MRA), is recommended in certain situations—particularly when a skull fracture involves the

carotid canal The carotid canal is a passage in the petrous part of the temporal bone of the skull through which the internal carotid artery and its internal carotid (nervous) plexus pass from the neck into (the middle cranial fossa of) the cranial cavity. ...

, due to the risk of post-traumatic vasospasm impairing cerebral perfusion. These imaging techniques are also used when the hemorrhage pattern is atypical for trauma, as in isolated SAH located in the basal cisterns, Sylvian fissure, or anterior interhemispheric fissure. Such patterns may suggest ruptured intracranial aneurysms, and warrant further investigation.

Non-traumatic

Hypertensive bleed

Hypertensive intracerebral hemorrhage (ICH) typically occurs in individuals between 50 and 60 years of age and is associated with high mortality, with case fatality rates ranging from 30% to 50%. Such hemorrhages are typically located in the

cerebellum The cerebellum (: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as it or eve ...

, or occipital lobes. Less common locations, such as lobar bleeds within the cerebral cortex or intracranial bleeds in people younger than 50 years of age, should prompt further investigation for alternative etiologies, such as brain tumors or

cerebral arteriovenous malformation A cerebral arteriovenous malformation (cerebral AVM, CAVM, cAVM, brain AVM, or BAVM) is an abnormal connection between the arteries and veins in the brain—specifically, an arteriovenous malformation in the cerebrum. Signs and symptoms The mos ...

. The size of the hemorrhage can vary, ranging from small, asymptomatic lesions to large hematomas causing mass effect and increased intracranial pressure. Follow-up CT imaging is recommended to monitor hematoma expansion, ventricular extension, or progressive cerebral edema, all of which are associated with poorer outcomes. CT angiography (CTA) may be used to assess active bleeding. The presence of a "spot sign"—contrast pooling within the hematoma on delayed-phase imaging—suggests ongoing hemorrhage and is considered a predictor of hematoma and worse clinical prognosis.

Cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is a cerebrovascular accident disorder characterized by the deposition of

amyloid beta Amyloid beta (Aβ, Abeta or beta-amyloid) denotes peptides of 36–43 amino acids that are the main component of the amyloid plaques found in the brains of people with Alzheimer's disease. The peptides derive from the amyloid-beta precursor prot ...

(AB) peptide within the brain. Accumulation of such peptide proteins within the walls of the arteries can cause weakening of the walls and can increase the risk of microhemorrhages. SAH due to CAA typically occurs in individuals over the age of 60 and can present with transient motor or sensor symptoms. Hemorrhages associated with CAA are usually localized to the lobar white matter adjacent to the cortex, sparing deeper brain structure such as the basal ganglia, brainstem, and posterior fossa. This pattern helps differentiate CAA-related hemorrhage from other causes, such as

vasculitis Vasculitis is a group of disorders that destroy blood vessels by inflammation. Both artery, arteries and veins are affected. Lymphangitis (inflammation of lymphatic vessels) is sometimes considered a type of vasculitis. Vasculitis is primarily c ...

. Diagnosis of CAA is often based on the Boston criteria, which incorporate clinical, radiological, and histopathological findings to estimate the likelihood of CAA as the cause of hemorrhage. A definitive diagnosis requires histopathological confirmation via brain biopsy or post-mortem examination. On CT imaging, CAA-related hemorrhages appear as hyperdense lobar intra-axial bleeds, typically in subcortical regions. Diffuse with white matter hypodensities may also be observed, suggesting chronic microangiopathic changes. MRI, especially using gradient echo (GRE) and susceptibility-weighted imaging (SWI) sequences, can detect microbleeds and cortical superficial siderosis, which appear as blooming artifacts—a key imaging feature of CAA.

Hemorrhagic conversion of ischemic infarction

43% of those with infarcted brain tissue will develop hemorrhagic conversion. Risk of hemorrhagic is further increased with recanalisation of veins or arteries. Several types of hemorrhages can occur such as petechial hemorrhages around the infarcted margin (HI1), confluent petechial hemorrhages within the infarcted tissue (HI2), hematoma occupying less than 30% of the infarcted tissue (PH1), hematoma involving greater than 30% of infarcted tissue with small mass effect (PH2), and hematoma involving greater than 30% of the infarcted tissue with significant mass effect. However, only PH2 is clinically significant. Those who has infarction should be monitored frequently with CT brains to access hemorrhagic conversions or worsening vasogenic oedema that may require neurosurgical decompression. Dual energy CT scan maybe useful to differentiate the high densities caused by reperfusion hemorrhage (bleeding after endovascular stroke treatment) and high density due to iodinated contrast administered during

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 ...

Cerebral aneurysm

Besides from head injury, it may occur spontaneously, usually from a ruptured cerebral aneurysm (focal outpouchings with weakened walls on the arteries on the brain surface that are prone to rupture).

Symptom Signs and symptoms are diagnostic indications of an illness, injury, or condition. Signs are objective and externally observable; symptoms are a person's reported subjective experiences. A sign for example may be a higher or lower temperature ...

s of SAH include a severe

headache A headache, also known as cephalalgia, is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of Depression (mood), depression in those with severe ...

with a rapid onset (

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 ...

vomiting Vomiting (also known as emesis, puking and throwing up) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteritis, pre ...

, confusion or a lowered level of consciousness, and sometimes

seizure A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, o ...

s. CT scan has 100% sensitivity of detecting SAH at 6 to 24 hours after symptoms onset. The

diagnosis Diagnosis (: diagnoses) is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in a lot of different academic discipline, disciplines, with variations in the use of logic, analytics, and experience, to determine " ...

is generally confirmed with a

CT scan A computed tomography scan (CT scan), formerly called computed axial tomography scan (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 or ...

of the head. If CT scan is normal but SAH is still strongly suspected, lumbar puncture can be done at six to twelfth hours after the onset of headache. This is to determine the presence of blood within the

(CSF). Those with SAH will have blood and

bilirubin Bilirubin (BR) (adopted from German, originally bili—bile—plus ruber—red—from Latin) is a red-orange compound that occurs in the normcomponent of the straw-yellow color in urine. Another breakdown product, stercobilin, causes the brown ...

within their CSF because of the degradation of their

red blood cells Red blood cells (RBCs), referred to as erythrocytes (, with -''cyte'' translated as 'cell' in modern usage) in academia and medical publishing, also known as red cells, erythroid cells, and rarely haematids, are the most common type of blood cel ...

. Meanwhile, those who has blood within CSF due to traumatic lumbar puncture will not have bilirubin within CSF. SAH is generally located within basal cisterns, extends diffusely to all subarachnoid spaces ( cerebral sulci) or into the

ventricular system In neuroanatomy, the ventricular system is a set of four interconnected cavities known as cerebral ventricles in the brain. Within each ventricle is a region of choroid plexus which produces the circulating cerebrospinal fluid (CSF). The ventric ...

, or brain parenchyma. Modified Fisher scale is used to describe the volume and distribution of SAH, just predicting the probability of cerebral artery vasospasm after SAH. Treatment is by prompt

neurosurgery Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the specialty (medicine), medical specialty that focuses on the surgical treatment or rehabilitation of disorders which affect any portion of the nervous system ...

or radiologically-guided interventions with medications and other treatments to help prevent recurrence of the bleeding and complications. Since the 1990s, many aneurysms are treated by a minimal invasive procedure known as endovascular coiling, which is carried out by instrumentation through large blood vessels. However, this procedure has higher recurrence rates than the more invasive craniotomy with clipping.

Cerebral ateriovenous malformation

Cerebral ateriovenous malformation (Cerebral AVM) is characterised by abnormal shunting between cerebral arteries and veins without going through capillaries. Instead the blood goes through a collection of small vessels from arteries to veins. These collection of abnormal small vessels is termed as "nidus". This condition happens in 0.1% of the population has a risk of 2 to 4% per year for intracranial bleeding. Once ruptured, it results in intraparenchymal hemorrhage, intraventricular hemorrhage and SAH. Rupture of cerebral AVM often occurs in young people and children. Cerebral AVM can be diagnosed by

computed tomography 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, im ...

(CTA) brain,

magnetic resonance angiography Magnetic resonance angiography (MRA) is a group of techniques based on magnetic resonance imaging (MRI) to image blood vessels. Magnetic resonance angiography is used to generate images of arteries (and less commonly veins) in order to evaluate ...

(MRA) brain, or digital subtraction angiography (DSA). DSA is important to determine whether there is nidal or perinidal aneurysm.

Dural arteriovenous fistulae

Dural arteriovenous fistulae (DAVF) is the direct connection between dural or cerebral arteries with dural venous sinuses or cortical veins. It accounts for 10 to 15% of intracranial arteriovenous shunts. DAVF lacks a nidus. Signs and symptoms of DAVF are: headache,

tinnitus Tinnitus is a condition when a person hears a ringing sound or a different variety of sound when no corresponding external sound is present and other people cannot hear it. Nearly everyone experiences faint "normal tinnitus" in a completely ...

, neurological deficits involving

cranial nerves Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and f ...

, and increased intracranial pressure. DAVF once ruptured, will produce intraparenchymal hemorrhage or SAH. Increase in number of vessels near dural venous sinuses as seen on CTA is suggestive of DVAF. 4DCT may increase the sensitivity of detecting DAVF. In MRI scans, susceptibility weighted imaging (SWI) and arterial spin labelling sequences (labelling protons in blood without the use of contrast media to determine blood flow) are useful in evaluating DAVF. The patterns of draining veins from the fistula determines the risk of DAVF rupture. Increased pressure within the dural venous sinuses causes backpressure into the cortical veins, thus making cortical veins more prone to rupture. The risk of hemorrhage is graded by Cognard and Borden grading systems. These grading systems are based upon the DSA.

Cortical venous and cerebral venous sinus thrombosis

Dural venous sinus thrombosis (DVST) and cortical venous thrombosis (CVT) commonly presents with headache, increased intracranial pressure, or seizures. DVST is more common than CVT. DVST are frequently caused by infections in the skull base, dehydration,

thrombophilia Thrombophilia (sometimes called hypercoagulability or a prothrombotic state) is an abnormality of blood coagulation that increases the risk of thrombosis (blood clots in blood vessels). Such abnormalities can be identified in 50% of people who ...

meningioma Meningioma, also known as meningeal tumor, is typically a slow-growing tumor that forms from the meninges, the membranous layers surrounding the brain and spinal cord. Symptoms depend on the location and occur as a result of the tumor pressing ...

, and other dural tumours. On CT scans, brain parenchymal hemorrhage that does not confined to specific arterial territory along with hyperdense appearance on dural venous sinuses raises the suspicion of DVST. Further evaluation with CT venography, MR venography, and post gadolinium MRI provides accurate diagnosis of venous thrombosis and follow-up after treatment. These studies demonstrate thrombus as filling defect or lack of signal.

Vasculitis and vasculopathy

Those with vasculitis may be presented with headache, behavioural changes, neurological deficits, or intracranial bleeding. Sulcal SAH is the most common form of intracranial bleed caused by vasculitis. On CT scans, sulcal SAH is seen as hyperdensity within the cerebral sulcus, while on MRI, it is seen as hyperintensity on FLAIR sequence, and hypointensity on GRE/SWI sequence. DSA is important in making the diagnosis of vasculitis or vasculopathy.

Mycotic aneurysm

It is arterial outpouchings arise from distal cerebral arteries. These are

pseudoaneurysm A pseudoaneurysm, also known as a false aneurysm, is a locally contained hematoma outside an artery or the heart due to damage to the vessel wall. The injury passes through all three layers of the arterial wall, causing a leak, which is contai ...

, caused by thrombus clogging the distal arteries, which results in inflammation and small tears at the site of occlusion. These inflammation and thrombis can caused by

infective endocarditis Infective endocarditis is an infection of the inner surface of the heart (endocardium), usually the heart valve, valves. Signs and symptoms may include fever, petechia, small areas of bleeding into the skin, heart murmur, feeling tired, and anem ...

artificial heart valve An artificial heart valve is a one-way valve implanted into a person's heart to replace a heart valve that is not functioning properly ( valvular heart disease). Artificial heart valves can be separated into three broad classes: mechanical he ...

or other heart problems. Similar to vasculitis, rupture of mycotic aneurysm also causes SAH in cerebral sulci, mostly located in the vertex. If mycotic aneurysm is located more proximally, it will produce diffuse SAH pattern. CTA or MRA would produce focal outpouching or increase in diameter of the vessel. Meanwhile, GRE/SWI MRI sequence would produce focal hypointensity. Small mycotic aneurysms are difficult to be seen on CT or MRI. Thus, DSA is useful in identifying these lesions.

Management

For those who is already on blood thinners such as

clopidogrel Clopidogrel, sold under the brand name Plavix among others, is an antiplatelet drug, antiplatelet medication used to reduce the risk of Cardiovascular disease, heart disease and stroke in those at high risk. It is also used together with aspi ...

for prevention of

myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...

, traumatic intracranial hemorrhage should prompt the use of platelet function assays ( PFA-100) to assess the effect of these antiplalelet agents. After that,

plateletpheresis Plateletpheresis (more accurately called thrombocytapheresis or thrombapheresis, though these names are rarely used) is the process of collecting thrombocytes, more commonly called platelets, a component of blood involved in hemostasis, blood clot ...

can be started to increase the aggregation of platelets, thus stopping the intracranial bleed. In those with impaired kidney functions,

desmopressin Desmopressin, sold under the trade name DDAVP among others, is a medication used to treat diabetes insipidus, bedwetting, hemophilia A, von Willebrand disease, and high blood urea levels. In hemophilia A and von Willebrand disease, it should ...

cryoprecipitate Cryoprecipitate, also called cryo for short, or Cryoprecipitate Antihemophilic factor (AHF), is a frozen blood product prepared from blood plasma. To create cryoprecipitate, plasma is slowly thawed to 1–6 °C. A cold-insoluble precipita ...

can be used instead. From limited observational data, it may be relatively safe to restart

blood thinners An anticoagulant, commonly known as a blood thinner, is a chemical substance that prevents or reduces the coagulation of blood, prolonging the clotting time. Some occur naturally in blood-eating animals, such as leeches and mosquitoes, which h ...

after an ICH as it is associated with reduced thromboembolic complications with similar risk of recurrent hemorrhage when compared to those did not start blood thinners after an ICH.

Comparison

References

External links

{{Authority control Neurotrauma Types of stroke