Current status of perimesencephalic non-aneurysmal subarachnoid hemorrhage

Abstract

Perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSAH) is a distinctive disease, representing SAH centered in perimesencephalic cisterns, with negative angiography findings. In recent years, the number of patients with PNSAH has increased significantly; however, the knowledge of PNSAH is insufficient. Therefore, we performed a review of the literature from a PubMed search and recounted our understanding of PNSAH. In this review, we summarized that current high-resolution computed tomography angiography is an acceptable replacement for digital subtraction angiography to rule out aneurysms in PNSAH with strict criteria. The current hypothesis about the etiology of PNSAH is that there is deep vein rupture from aberrant venous anatomy and increased intracranial venous pressure. PNSAH is associated with mild symptoms and lower rates of hydrocephalus and symptomatic vasospasm. For PNSAH, conservative treatment has been the mainstream treatment. PNSAH has a benign clinical course and an excellent prognosis; in long-term follow-up, re-bleeding and death were uncommon.

Non-Aneurysmal Perimesencephalic Subarachnoid Hemorrhage: A Literature Review

“…Although the risk factors linked to this pathological entity are comparable to those associated with aneurysmal bleeding, the aetiology remains relatively unknown as there are several possible causative factors mostly linking its occurrence to several embryological venous drainage anomalies. The diagnosis of this pathology is rather difficult as it requires angiographic expertise to exclude small-size aneurysms; the most used tools include conventional DSA, CT angiography and plain CT scans [ 76 ].…”

“…The occurrence of complications appears to be closely linked to the size of the haemorrhage, while the risk of complications can be assessed by referring to imagistic scales such as the Fisher scale. The long-term follow-up and long-term prognosis appears to be generally favourable in this case as long-term complications appear to be related to a degree of decline in the cognitive function, with little to no residual focal neurological deficits [ 76 ].…”

Stroke Unit as an alternative to Intensive Care Unit for initial hospital admission of low-grade non-aneurysmal subarachnoid haemorrhage: A safety and cost-minimisation analysis

“…Non-aneurysmal SAH accounts for a non-negligible percentage (10%-20%) of all spontaneous SAH cases. Although conventionally considered a more benign form of SAH, [11][12][13][14] the concern about the risk of paradigmatic complications of SAH usually leads to long hospitalisation periods. According to clinical guidelines, customary management involves admission to the ICU and subsequent transfer to a regular neurological or neurosurgical ward once the high-risk period of complications is over.…”

“…[7][8][9][10] Non-aneurysmal SAH (naSAH) accounts for about 10%-20% of all spontaneous SAH cases and is associated with a more benign course. [11][12][13][14] However, the paradigmatic complications of SAH may still occur, especially in cases with a diffuse pattern of blood distribution in contrast with a perimesencephalic pattern. 15,16 Conventionally, aneurysmal SAH patients are admitted to the Intensive Care Unit (ICU) for specialised care during the acute stage and are subsequently transferred to the neurosurgical ward once the high-risk period is over.…”

“…7–10 Non-aneurysmal SAH (naSAH) accounts for about 10%–20% of all spontaneous SAH cases and is associated with a more benign course. 11–14 However, the paradigmatic complications of SAH may still occur, especially in cases with a diffuse pattern of blood distribution in contrast with a perimesencephalic pattern. 15,16…”