Perimesencephalic subarachnoid hemorrhage

J.Sales-Llopis

Neurosurgery Department, General University Hospital Alicante, Spain

• Is there any relationship between the perimesencephalic subarachnoid hemorrhage and brainstem venous variations? A susceptibility-weighted imaging study
• Perimesencephalic Subarachnoid Hemorrhage Is Not Always a Benign Condition: Hemorrhage Volume as a Predictor for Complications and Clinical Outcome
• Subarachnoid hemorrhage part 1 : Pathophysiology, diagnostics and special forms
• Prognostic Factors and Imaging Strategies in Unknown Subarachnoid Hemorrhage: A Retrospective Study
• Benign versus sinister aetiologies underlying basal cistern subarachnoid haemorrhage: a case series
• Cranial Nerve Palsies and Peri-Mesencephalic Subarachnoid Haemorrhage: A Case Report and Review of the Literature
• Association of SSRI and SNRI use with incident hyponatremia after subarachnoid hemorrhage
• Transcarotid flow reversal for proximal control during cerebral aneurysm clip reconstruction: illustrative case

Perimesencephalic subarachnoid hemorrhage (PMSAH) is a distinct pattern of subarachnoid hemorrhage (SAH), which is centered on the basal cisterns around the midbrain.

Perimesencephalic Subarachnoid Hemorrhage Epidemiology.

There are two main categories based on the distribution of blood on the initial CT:

Blood is confined to the cisterns around the midbrain and pons, especially:

Interpeduncular cistern

Prepontine cistern

Ambient cistern

Minimal or no extension into lateral sylvian fissures or interhemispheric fissure

No intraventricular or intraparenchymal hemorrhage

No aneurysm on CTA/DSA

Blood starts in the perimesencephalic region but extends into:

Sylvian fissures

Interhemispheric fissure

Other cortical cisterns

May raise suspicion for aneurysm → usually leads to repeat angiography to exclude a missed aneurysm

Still, if angiography remains negative, often behaves like classic PNSAH

see Non-aneurysmal perimesencephalic subarachnoid hemorrhage.

see Perimesencephalic Subarachnoid Hemorrhage Etiology.

see Subarachnoid hemorrhage clinical features.

Perimesencephalic subarachnoid hemorrhage diagnosis.

Perimesencephalic subarachnoid hemorrhage treatment.

Perimesencephalic subarachnoid hemorrhage outcome

van Gijn et al. studied 28 patients with subarachnoid hemorrhage and normal angiograms. On early CT (within 5 days) in 13 cases, blood was seen mainly or only in the cisterns around the midbrain. This pattern of hemorrhage was found in only 1 of 92 patients with a ruptured aneurysm. None of the unexplained perimesencephalic hemorrhages was associated with intracerebral hematoma or intraventricular hemorrhage. The clinical features also differed from those of aneurysmal hemorrhage; loss of consciousness was rare, and after 3 months, all 13 patients had returned to normal life. The cause of this benign disorder remains elusive, but a venous or capillary source seems likely ¹⁾

Perimesencephalic subarachnoid hemorrhage case reports