Subarachnoid Hemorrhage: What Is It?

Patients with a subarachnoid hemorrhage often present with a characteristic combination of symptoms. The most important of all is the sudden severe headache.
Subarachnoid Hemorrhage: What Is It?

Last update: 16 December, 2022

A subarachnoid hemorrhage (SAH) is a type of bleeding that occurs in the brain. To be more specific, it is bleeding that occurs between the arachnoid membrane and the pia mater membrane that surrounds the brain (this area is known as the subarachnoid space).

This is a complication that requires a quick and timely response in order to prevent the associated problems in the patient’s health. Let’s have a look at everything that experts know about it.

Causes of a subarachnoid hemorrhage

As experts point out, there are two main causes of a subarachnoid hemorrhage: a traumatic injury and an aneurysm rupture. Traumatic injuries group the majority of cases of this type of hemorrhage. For example, motor vehicle-related accidents, head injuries, falls, attacks, and more.

In the case of subarachnoid hemorrhages of non-traumatic etiology, and following the evidence, up to 85% of them are explained by a ruptured aneurysm. Other possible explanations for the episodes are as follows:

  • Drug abuse (such as cocaine)
  • Dural arteriovenous fistula
  • Arteriovenous malformations
  • Anticoagulation disorders
  • Sickle cell anemia

Subarachnoid hemorrhages caused by ruptured aneurysms are more common in people between the ages of 40 and 60, particularly women.

Suffering from hypertension, smoking, drinking alcohol excessively, following sympathomimetic drug treatment, and having a family history of aneurysms are considered risk factors for its manifestation.

Autosomal dominant polycystic kidney disease (ADPKD) is known to increase the risk of this type of bleeding up to five times. Despite all this, experts warn that in up to 10% of cases a clear source of bleeding cannot be found.

Symptoms of a subarachnoid hemorrhage

Vomiting in subarachnoid hemorrhage.
Intracranial hypertension caused by subarachnoid hemorrhage usually causes vomiting of abrupt onset.

Patients with a subarachnoid hemorrhage often present with a characteristic combination of symptoms. The most important of all is the sudden severe headache. In fact, the evidence tells us that up to 1/3 of the patients only develop this symptom. Let’s see other common signs that usually accompany it below:

  • Nausea and vomiting
  • Blurred and double vision (diplopia)
  • Confusion and difficulty concentrating
  • Stiffness in the neck area and upper back
  • Sensitivity to light (photophobia)
  • Intraocular hemorrhage (known in this context as Terson’s syndrome)
  • Alterations in motor skills on one side of the body (hemiparesis)
  • Droopy eyelids
  • Problems speaking
  • Seizures
  • Cardiac arrhythmias

Headaches are the first manifestation. They appear in a matter of seconds or minutes, and are characterized by being pulsating and spreading progressively to the back of the head (occiput).

The most intense point of pain is during the first few seconds, and then it gradually reduces. Not all intense headaches are because if a hemorrhage of this type. In fact, it’s well known that only 1% of people turning up at the emergency department for headaches have this condition.

Diagnostic options

During the first 6 hours after the onset of symptoms, the preferred method for diagnosing this hemorrhage is computed tomography.

If the results are diffuse, or the 6-hour window has been exceeded, a complementary magnetic resonance and angiogram will be considered. Some laboratory tests can give clues to help confirm the diagnosis.

Among the most common differential diagnoses, we highlight pseudosubarachnoid hemorrhage, neurosarcoidosis, granulomatous meningitis, and bacterial and tuberculous meningitis.

If the diagnosis is confirmed, the professionals will classify it based on the international scale. This classifies the type of bleeding based on the symptoms and offers an idea about its severity and prognosis.

Treatment for subarachnoid hemorrhage

Subarachnoid hemorrhage often causes vomiting.
Neurosurgery is usually the most convenient option in cases of subarachnoid hemorrhage.

Subarachnoid hemorrhages are considered a medical emergency. Therefore, treatment should be performed in the intensive care unit. The first step is to stabilize the patient and obtain a complete neurosurgical evaluation.

Many patients may require intubation for airway protection, and all require constant assessment of blood pressure, pulse, and respiratory rate.

When the patient manifests hydrocephalus, the placement of an external ventricular drain is considered. The choice of method to address the bleeding depends on the causes, for example, the type of injury or the type of aneurysm.

The surgical removal of blood, occlusion of the bleeding area, the use of clamps or coils to reduce risk, clipping, coiling of aneurysms, and other options are among the options available.

In the company of all this, drugs will be administered to avoid the associated complications of bleeding (seizures, vasospasm, and others). The prognosis depends on a variety of factors, such as the severity of the episode and the speed with which it has been dealt with. Unfortunately, most bleeding of this type is associated with a poor outcome.

As Johns Hopkins Medicine reminds us, part of long-term treatment is addressing the risk factors associated with subarachnoid hemorrhage. For example, smoking and high blood pressure. In addition to this, a close and continuous evaluation is required to follow the patient’s progress.

  • Linn FH, Rinkel GJ, Algra A, van Gijn J. Headache characteristics in subarachnoid haemorrhage and benign thunderclap headache. J Neurol Neurosurg Psychiatry. 1998 Nov;65(5):791-3.
  • Kanne JP, Talner LB. Autosomal dominant polycystic kidney disease presenting as subarachnoid hemorrhage. Emerg Radiol. 2004 Dec;11(2):110-2.
  • Kairys, N., Das, J. M., & Garg, M. Acute Subarachnoid Hemorrhage. In StatPearls [Internet]. StatPearls Publishing. 2021.
  • Marcolini E, Hine J. Approach to the Diagnosis and Management of Subarachnoid Hemorrhage. West J Emerg Med. 2019 Mar;20(2):203-211.
  • Ramirez-Lassepas M, Espinosa CE, Cicero JJ, Johnston KL, Cipolle RJ, Barber DL. Predictors of intracranial pathologic findings in patients who seek emergency care because of headache. Arch Neurol. 1997 Dec;54(12):1506-9.
  • Ziu, E., & Mesfin, F. B. Subarachnoid Hemorrhage. 2017.

Este texto se ofrece únicamente con propósitos informativos y no reemplaza la consulta con un profesional. Ante dudas, consulta a tu especialista.