Perimesencephalic subarachnoid hemorrhage diagnosis

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• Benign versus sinister aetiologies underlying basal cistern subarachnoid haemorrhage: a case series
• Follow-Up Imaging in Angiography-Negative Spontaneous Subarachnoid Hemorrhage
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• Basilar Artery Perforator Aneurysms - The Phantom Menace of the Intracranial Universe

Perimesencephalic subarachnoid hemorrhage has been defined as subarachnoid haemorrhage, which on CT within three days of symptom onset:

It is centred anteriorly to the pons and midbrain

May extend into the basal and suprasellar cisterns and into the proximal/basal Sylvian and interhemispheric fissures may settle as sediment in the occipital horns of the lateral ventricles but there is no overt intraventricular haemorrhage

Is recommended for PMSAH to investigate for possible aneurysmal cause.

Undertaking a DSA after a negative CTA may not add any further diagnostic value in patients with PMSAH and may lead to net harm. This observation needs to be validated in a large-scale prospective multicenter study with complete case ascertainment and robust data on CTA and DSA complications ¹⁾

Perimesencephalic subarachnoid hemorrhage cerebral angiography