What are the signs and symptoms of an arachnoid (cerebrospinal fluid-filled space between the brain and the skull) hemorrhage?

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Last updated: June 11, 2025View editorial policy

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From the Guidelines

The most characteristic symptom of an arachnoid hemorrhage is a sudden, explosive headache often described as "the worst headache of my life" or a "thunderclap headache," which is reported by 80% of patients who can give a history, as stated in the guidelines for the management of aneurysmal subarachnoid hemorrhage 1.

Signs and Symptoms

The signs and symptoms of an arachnoid hemorrhage include:

  • A sudden, severe headache that reaches maximum intensity almost immediately
  • Nausea and vomiting
  • Neck stiffness or pain (meningismus)
  • Sensitivity to light (photophobia)
  • Brief loss of consciousness
  • Confusion
  • Irritability
  • Seizures
  • Blurred or double vision
  • Weakness or numbness on one side of the body
  • Difficulty speaking In severe cases, a person might lapse into a coma.

Importance of Early Recognition

It is essential to recognize the warning signs of an arachnoid hemorrhage, as delays in treatment can significantly increase the risk of permanent neurological damage or death, with misdiagnosis associated with a nearly 4-fold higher likelihood of death or disability at 1 year in patients with minimal or no neurological deficit at the initial visit 1.

Diagnostic Approach

The cornerstone of diagnosis is a noncontrast cranial CT scan, which has a high sensitivity for detecting a hemorrhage, especially in the first 12 hours after the event, as noted in the guidelines for the management of aneurysmal subarachnoid hemorrhage 1.

Warning Leaks

Some patients may experience a warning leak or sentinel hemorrhage before a major rupture, which can be a lifesaving diagnosis if recognized early, with the headache associated with a warning leak usually being milder than that associated with a major rupture, but it may last for a few days, as discussed in the guidelines for the management of aneurysmal subarachnoid hemorrhage 1.

From the Research

Signs and Symptoms of Arachnoid Hemorrhage

The signs and symptoms of an arachnoid hemorrhage can vary, but some common indicators include:

  • Sudden and severe headache, often described as the worst headache of a person's life 2, 3
  • Nausea and vomiting 3
  • Confusion, disorientation, and altered mental state 4
  • Seizures 4
  • Sudden loss of consciousness 5
  • Weakness or numbness in the face, arm, or leg 5
  • Difficulty speaking or understanding speech 5
  • Vision changes, such as double vision or loss of vision 6
  • Sudden and severe pain in the neck or back 6

Diagnosis and Treatment

Diagnosis of an arachnoid hemorrhage typically involves:

  • Computed Tomography (CT) scan or Magnetic Resonance Imaging (MRI) to confirm the presence of blood in the subarachnoid space 2, 6
  • Lumbar puncture to check for blood in the cerebrospinal fluid 3
  • Transcranial Doppler ultrasonography to monitor blood flow in the brain 4 Treatment may involve:
  • Medications to control blood pressure and prevent vasospasm, such as nimodipine or nicardipine 2, 5, 6
  • Surgery to repair the aneurysm or remove the blood clot 5
  • Intensive care unit (ICU) monitoring to manage complications and prevent further bleeding 3, 6

Complications and Outcomes

Complications of an arachnoid hemorrhage can include:

  • Cerebral vasospasm, which can lead to delayed cerebral ischemia (DCI) 2, 6
  • Rebleeding, which can worsen outcomes 4
  • Hydrocephalus, which can require surgical intervention 6
  • Ventriculitis, which can increase the risk of infection 6 Outcomes can vary depending on the severity of the hemorrhage, the presence of complications, and the effectiveness of treatment 3, 6

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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