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Updated: Jan 31, 2026
A Murine Model of Subarachnoid Hemorrhage
Published on: November 21, 2013
Ischemic Lesions in Acute and Subacute Perimesencephalic Subarachnoid Hemorrhage
Isabel Fragata1,2, Nuno Canto-Moreira3,4, Patrícia Canhão5,6
11 Department of Neuroradiology, Hospital São José, Centro Hospitalar Lisboa Central, Rua José António Serrano, Lisbon 110, Portugal.
Objective:
Perimesencephalic hemorrhage (PMH) is a subtype of nonaneurysmal subarachnoid hemorrhage (SAH). In patients with aneurysmal SAH, the occurrence of acute ischemic lesions is associated with severity and poor outcome. We investigated the frequency of ischemic lesions on DWI in patients with PMH and compared it with the frequency of ischemic lesions in patients with aneurysmal SAH.
Subjects And Methods:
From a prospective cohort of 80 patients with acute spontaneous SAH, we included 15 patients with PMH and 39 patients with aneurysmal SAH who were matched on the basis of their clinical condition (World Federation of Neurological Societies grade 1 or 2). MRI was performed less than 72 hours after SAH, 8-10 days after SAH, or at both points in time. The number and distribution of lesions previously seen on DWI that were also seen on a second MRI examination were assessed. Nonparametric tests were used to compare groups.
Results:
Early acute ischemic lesions (those identified < 72 hours after SAH) were found in 46.2% of patients with PMH and in 62.9% of patients with aneurysmal SAH. No significant differences in the number of acute ischemic lesions between groups were noted less than 72 hours after SAH (median, 0.5 lesion [interquartile range {IQR}, two lesions] in patients with PMH vs one lesion [IQR, three lesions] in patients with aneurysmal SAH [p = 0.48] or 8-10 days after SAH (median, 0.5 lesion [IQR, four lesions] in patients with PMH vs 1.5 lesions [IQR, three lesions] in patients with aneurysmal SAH [p = 0.26]). However, 58.3% of patients with aneurysmal SAH had new infarcts at 8-10 days, compared with 7.1% of patients with PMH. Patients with PMH had diffuse ischemic lesions, whereas patients with aneurysmal SAH in the anterior circulation had mainly supratentorial lesions.
Conclusion:
Early ischemic lesions appeared on DWI both in patients with PMH and in patients with aneurysmal SAH. The number of lesions increased during the time window for vasospasm, mainly in patients with aneurysmal SAH. Further studies are required to better understand the pathophysiologic mechanisms behind early ischemia in patients with PMH and their impact on prognosis.
Insights
Early ischemic lesions occur in both perimesencephalic hemorrhage (PMH) and aneurysmal subarachnoid hemorrhage (SAH). While initial lesion numbers are similar, PMH patients show fewer new infarcts later, suggesting different pathophysiologic mechanisms.
Area of Science:
- Neurology
- Neuroradiology
- Neurocritical Care
Background:
- Perimesencephalic hemorrhage (PMH) is a distinct subtype of nonaneurysmal subarachnoid hemorrhage (SAH).
- Acute ischemic lesions in aneurysmal SAH correlate with clinical severity and prognosis.
- The occurrence and characteristics of ischemic lesions in PMH require further investigation.
Purpose of the Study:
- To determine the frequency of diffusion-weighted imaging (DWI) detected ischemic lesions in patients with PMH.
- To compare the frequency and evolution of ischemic lesions in PMH with those in aneurysmal SAH.
Main Methods:
- Prospective cohort study including 15 PMH patients and 39 matched aneurysmal SAH patients (WFNS grade 1-2).
- Serial MRI including DWI performed within 72 hours and/or 8-10 days post-SAH.
- Assessment of lesion number, distribution, and evolution; nonparametric tests for group comparison.
Main Results:
- Early ischemic lesions (<72h) were present in 46.2% of PMH patients and 62.9% of aneurysmal SAH patients, with no significant difference in number.
- Later infarcts (8-10 days) were significantly less frequent in PMH (7.1%) compared to aneurysmal SAH (58.3%).
- PMH lesions were diffuse, while aneurysmal SAH lesions were mainly supratentorial, particularly in the anterior circulation.
Conclusions:
- Early ischemic lesions are detectable on DWI in both PMH and aneurysmal SAH.
- Aneurysmal SAH shows a significant increase in new infarcts during the vasospasm window, unlike PMH.
- Further research is needed to elucidate the mechanisms and prognostic implications of early ischemia in PMH.
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