Pseudosubarachnoid hemorrhage
Updates to Article Attributes
Body
was changed:
Pseudo-subarachnoid haemorrhage is the a sign related to apparent increased attenuation within the basal cisterns which simulates a true subarachnoid haemorrhage (SAH).
Pathology
Causes and associations
The most common cuase is cerebral oedema where there is a decrease in parenchyma attenuation and engorgement and dilatation of the superficial venous structures due an increased intracranial pressure. 1,2 This is seen in anoxia and recent resuscitation from cardiopulmonary arrest.
Other causes include:
- severe meningitis: breakdown of the blood brain barrier allowing mildly hyperdense proteinaceous material to leak into the subarachnoid space 3
- venous sinus thrombosis
- bilateral large subdural haemorrhage producing effacement of sulci and basilar cisterns and the false impression of blood in the subarachnoid space 5
- intrathecal contrast
Radiographic features
CT
- usually symmetrical density confined to basal cisterns (i.e. no sulcal density)
- 30-40 HU (compared with true acute SAH ~ 60HU)
- often seen with generalised cerebral oedema or basal cistern effacement
- the appearances thought due to combination of
- cisternal effacement
- distention +/- thrombosis of vessels
- adjacent brain hypoattenuation accentuating contrast difference
Given et al. reviewed 7 cases of generalised cerebral oedema accompanied by increased basal cisternal attenuation which were all found not to have subarachnoid blood at lumbar puncture or autopsy 1.
Differential diagnosesdiagnosis
- true subarachnoid haemorrhage
- acute leptomeningitis mimicking a subarachnoid haemorrhage 3
-</ul><p>Given et al. reviewed 7 cases of generalised cerebral oedema accompanied by increased basal cisternal attenuation which were all found not to have subarachnoid blood at lumbar puncture or autopsy <sup>1</sup>.</p><h4>Differential diagnoses</h4><ul>- +</ul><p>Given et al. reviewed 7 cases of generalised cerebral oedema accompanied by increased basal cisternal attenuation which were all found not to have subarachnoid blood at lumbar puncture or autopsy <sup>1</sup>.</p><h4>Differential diagnosis</h4><ul>
Unable to process the form. Check for errors and try again.