Subarachnoid hemorrhage

Subarachnoid hemorrhage
International Classification (ICD) I60.-


Subarachnoid haemorrhage (SAB) is a haemorrhage that occurs in a specific region of the brain, namely in the space between the middle meninges (spinal meninges) and the surface of the brain, which is filled with cerebrospinal fluid (CSF). If one of the blood vessels, which are very numerous in this narrow, gap-shaped space, bursts, blood in the subarachnoid space leaks out and exerts pressure on the brain from the outside. The brain tissue itself, on the other hand, is not affected by the bleeding.

Subarachnoid hemorrhages are the cause of about 25% of all strokes caused by bleeding in the brain (hemorrhagic strokes). About 100,000 people are affected by SAB each year, but the likelihood increases at age 50 and is more common in women than in men.


The most common cause of a subarachnoid haemorrhage is a malformation of the arteries (arteries) at the base of the skull. The problem here is that the wall of these sac-like bulges (aneurysm), which are present from birth, do not have the same strength as normal vessels.

The aneurysm can often rupture even when the patient is completely at rest. Thus, it can be said that this process does not depend on any particular disease. In some people, however, physical exertion, such as lifting heavy weights, difficult bowel movements (heavy pressing), or sexual intercourse can be triggers. A sudden rise in blood pressure may also be a cause.

More rarely, a subarachnoid haemorrhage can occur as a result of craniocerebral injuries, sinus vein thrombosis (blood clot in a specific vessel), vascular inflammation and coagulation disorders. However, it often happens that no cause is found despite numerous examinations.

In general, however, it can be said that high blood pressure, smoking in combination with high cholesterol in the blood (hypercholesterolemia) and certain drugs (cocaine, heroin, amphetamines), increase the risk of subarachnoid hemorrhage.


A characteristic symptom of SAB is a sudden onset of severe headache, usually in the back of the head, which half of all sufferers describe as a "destructive headache". In addition, there is nausea, vomiting, photophobia and neck stiffness (meningismus).

If large hemorrhages are present, it can also lead to clouding of consciousness and unconsciousness, and in the worst case to respiratory and circulatory arrest.

Conversely, however, subarachnoid haemorrhage can be diagnosed in only one tenth of all patients who complain of sudden onset headache. Additional bleeding inside the brain tissue (intracerebral hemorrhage) can be assumed if seizures or paralysis of certain parts of the body also occur.

Experts classify the severity of SAB according to the WFNS (World Federation of Neurological Surgeons) and the Hunt and Hess scale. The severity of the symptoms is assessed and the score is determined using the Glasgow Coma Scale (GCS): The patient receives points for certain reactions (e.g..: Eye opening, reactions to pain stimuli and verbal utterances) made during the examination at the accident site. These points are added up at the end, with the worst score being 3 and the best score being 15.

  • Hunt and Hess Grade I: GCS score 15 No to mild headache, barely noticeable stiffness in the neck.
  • Hunt and Hess Grade II: GCS score 13-14 No neurological impairment, except possibly cranial nerve palsies due to direct pressure of subarachnoid blood on cranial nerves. In addition, severe headache may occur, as well as neck stiffness.
  • Hunt and Hess grade III: GCS score 13-14 Symptoms include drowsiness, confusion, or mild paralysis/sensitivity in some areas of the body.
  • Hunt and Hess grade IV: GCS score 7-12 Symptoms may include severe drowsiness or drowsiness, hemiplegia, circulatory, respiratory, or temperature regulation problems.
  • Hunt and Hess grade V: GCS score 3-6 The patient is already in a coma. According to neurological examinations, there is a risk that the brain could become trapped in the skull due to excessive pressure.


Because subarachnoid hemorrhage is life-threatening, anyone experiencing the onset of a massive, sudden, crushing headache that has never been experienced like this before should go to a hospital emergency room (if there are no other accompanying symptoms). If there are additional symptoms, the emergency physician should be called for help.

In the further course, the attending physician tries to determine the temporal development of the complaints, the exact course of which an accompanying person can give further information about. This is especially the case if the patient is confused or dazed. The family history is then taken in order to establish whether strokes and cerebral haemorrhages have occurred in the family before, as a frequent occurrence within the family is not uncommon.

Imaging techniques are used to diagnose SAB. A computed tomography (CT) scan usually reveals the subarachnoid hemorrhage as a flat, white area adjacent to the surface of the brain. While almost every SAB is detected by CT within the first 12 hours after hemorrhage, CT still detects 93% of the SAB present after 24 hours. For this reason, CT is considered the most reliable examination method in the acute phase after a subarachnoid hemorrhage. If 7 days have already passed since the onset of the SAB, a pathological change is only detected in every second CT finding.

In some cases, such as in extremely anaemic patients, SAB can only be detected by MRI or lumbar puncture. In response to the bleeding, the affected vessels may spasm (vasospasm), causing further paralysis in some affected individuals. These vasospasms can only be detected with the help of a special ultrasound examination of the brain vessels (transcranial Doppler sonography).

In order to determine the source of the bleeding (aneurysm), the doctor performs an X-ray imaging of the vessels (angiography), which is still considered the best method, although simpler examinations are now available (magnetic resonance angiography, CT angiography).


Intensive medical treatment is essential for those affected. Bed rest, as well as medication to prevent brain swelling and minimise vasospasms as far as possible, are basic treatment methods. The said vascular spasms (vasospasms) usually occur a few days to 2 weeks after the hemorrhage.

Surgery is necessary if the ruptured aneurysm is the cause of the subarachnoid hemorrhage, and thus must be immediately separated from the bloodstream. This can be done either by a neurosurgeon (clipping) or via the blood vessels by a neuroradiologist (endovascular coiling).

Clipping describes a method in which the surgeon ties off the aneurysm at its base with a clamp. This cuts off the blood supply to the aneurysm. However, this procedure can only be used if there is no vasoconstriction. For this reason, clipping operations are mainly performed on the first or second day after the first SAB symptoms. If there are vasospasms or a poor neurological condition, the operation must be postponed for a few days, as the spasm may be intensified by the operation.

In the coiling procedure, the doctor tries to insert a platinum coil into the aneurysm. To do this, a catheter must be advanced via the inguinal artery to the vessel outpouching. The purpose of the coiling is to fill the aneurysm and thus stop the bleeding. The advantage of this method is that it puts less strain on the circulation, and is less likely to cause vascular spasm. However, the disadvantage is that the effectiveness of coiling in eliminating the aneurysm is less than clipping. This is the reason why all patients with a coil are angiographed (x-ray of the vessels) 3 to 6 months after the operation for control.


Many factors play a role in the prognosis of a subarachnoid haemorrhage, such as the age of the patient, the severity of the haemorrhage and the location of the aneurysm. For example, aneurysms in the posterior parts of the brain usually have a worse outcome for the patient than those in the anterior areas of the brain. Thus, SAB is a life-threatening disease, with a total of about 45 to 50% of those affected dying within the first few months.

Early intensive medical treatment can help improve the prognosis. Nevertheless, some patients may be left with paralysis, coordination disorders or impaired mental performance.

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Danilo Glisic

Danilo Glisic

As a biology and mathematics student, he is passionate about writing magazine articles on current medical topics. Due to his affinity for facts, figures and data, his focus is on describing relevant clinical trial results.

The content of this page is an automated and high-quality translation from DeepL. You can find the original content in German here.



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