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Perimesencephalic hemorrhage: a nonaneurysmal and benign form of subarachnoid hemorrhage
Abstract:
We 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.
Insights
Perimesencephalic subarachnoid hemorrhage, often presenting in the midbrain cisterns, appears distinct from ruptured aneurysm bleeds. This condition shows a benign clinical course with excellent recovery, suggesting a non-aneurysmal origin.
Area of Science:
- Neurology
- Neurosurgery
- Radiology
Background:
- Subarachnoid hemorrhage (SAH) is a critical condition often caused by ruptured cerebral aneurysms.
- Perimesencephalic SAH (PESAH) is a subtype with a distinct radiological pattern and often normal initial angiograms.
Purpose of the Study:
- To characterize the clinical and radiological features of patients with subarachnoid hemorrhage and normal angiograms.
- To differentiate PESAH from aneurysmal SAH based on presentation and outcomes.
Main Methods:
- Retrospective review of 28 patients with SAH and normal angiograms.
- Analysis of early computed tomography (CT) findings, focusing on hemorrhage location.
- Comparison of clinical presentation and 3-month outcomes with a historical cohort of 92 patients with aneurysmal SAH.
Main Results:
- Thirteen patients (46%) presented with blood predominantly in the midbrain cisterns on early CT.
- This pattern was rare in aneurysmal SAH (1/92 patients).
- PESAH cases lacked intracerebral or intraventricular hemorrhage, had rare loss of consciousness, and showed full recovery at 3 months.
Conclusions:
- The distinct pattern of hemorrhage and benign clinical course suggest PESAH is a separate entity from aneurysmal SAH.
- The etiology of PESAH remains uncertain, but a venous or capillary source is hypothesized.
- Further research into the pathophysiology of PESAH is warranted.