Subarachnoid hemorrhage CT

Subarachnoid Hemorrhage Microchapters
Home
Patient Information
Overview
Classification
Pathophysiology
Causes
Differentiating Subarachnoid Hemorrhage from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms
Physical Examination
Laboratory Findings
CT
MRI
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Surgery
Primary Prevention
Secondary Prevention
AHA/ASA Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage (2012) Risk Factors/Prevention Natural History/Outcome Clinical Manifestations/Diagnosis Medical Measures to Prevent Rebleeding Surgical and Endovascular Methods Hospital Characteristics/Systems of Care Anesthetic Management Cerebral Vasospasm and DCI Hydrocephalus Seizures Associated With aSAH Medical Complications
Cost-Effectiveness of Therapy
Future or Investigational Therapies
Case Studies
Case #1
Subarachnoid hemorrhage CT On the Web
Most recent articles
Most cited articles
Review articles
CME Programs
Powerpoint slides
Images
American Roentgen Ray Society Images of Subarachnoid hemorrhage CT All Images X-rays Echo & Ultrasound CT Images MRI
Ongoing Trials at Clinical Trials.gov
US National Guidelines Clearinghouse
NICE Guidance
FDA on Subarachnoid hemorrhage CT
CDC on Subarachnoid hemorrhage CT
Subarachnoid hemorrhage CT in the news
Blogs on Subarachnoid hemorrhage CT
Directions to Hospitals Treating Subarachnoid hemorrhage
Risk calculators and risk factors for Subarachnoid hemorrhage CT

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]

CT

The diagnosis of subarachnoid hemorrhage cannot be made on clinical grounds alone. Medical imaging is usually required to confirm or exclude bleeding. The modality of choice is computed tomography (CT/CAT) of the brain. This has a high sensitivity (it will correctly identify >95% of the cases), especially on the first day after the onset of bleeding.

• Subarachnoid hemorrhage appears as a high-attenuating, amorphous substance that fills the normally dark CSF-filled subarachnoid spaces.
• These findings are most evident in the largest subarachnoid spaces, such as the suprasellar cistern and Sylvian fissures.
• Acute Subarachnoid hemorrhage is typically 50-60 HU.
• When CT scanning is performed several days to weeks after the initial bleed, the findings are more subtle.
  • The initial high-attenuation of blood and clot tend to decrease, and these appear as intermediate gray.
  • These findings can be isointense relative to normal brain parenchyma.
• In addition to detecting Subarachnoid hemorrhage, CT is useful in localizing the source of bleeding.

Images courtesy of RadsWiki

• 
  CT: Diffuse subarachnoid hemorrhage
• 
  CT: Diffuse subarachnoid hemorrhage
• 
  CT: Diffuse subarachnoid hemorrhage
• 
  CT: Diffuse subarachnoid hemorrhage

Once a subarachnoid hemorrhage is confirmed, the next question is about its origin. CT angiography (using radiocontrast) to identify aneurysms is generally the first step, as invasive angiography (injecting radiocontrast through a catheter advanced to the brain arteries) has a small rate of complications but is useful if there are plans to obliterate the source of bleeding, such as an aneurysm, at the same time.