Comparison between perimesencephalic nonaneurysmal subarachnoid hemorrhage and subarachnoid hemorrhage caused by posterior circulation aneurysms

Non-Aneurysmal Perimesencephalic Subarachnoid Hemorrhage: A Literature Review

Spontaneous non-aneurysmal subarachnoid haemorrhage (NAPMSAH) (addressing point 1) is a relatively rare occurrence in clinical settings as it is rarely misdiagnosed and usually involves a significantly better prognosis than the classical aneurysmal pattern. We hereby focused on a comprehensive analysis of this distinct pathological entity with the purpose of analysing possible pathophysiological entities, outcomes and treatment options involving this diagnosis with a focus on demographical, epidemiological and clinical data. The clinical setting includes focal neurological signs related to the anatomical structures, while computer tomography followed by tomographic angiography are the most common diagnosis tools, with a typical hyperdense lesion involving the midbrain, fourth ventricle and subthalamic areas without an angiographic correspondent, such as an aneurysmal pathology. Further investigations can also be used to highlight this diagnosis, such as interventional angiography or magnetic resonance imaging. Given the rarity of this condition and its relatively better prognosis, treatment options usually remain conservative. In the present review, the main characteristics of NAPMSAH are discussed.

Neurovascular disease, diagnosis, and therapy: Subarachnoid hemorrhage and cerebral vasospasm

The worldwide incidence of spontaneous subarachnoid hemorrhage is about 6.1 per 100,000 cases per year (Etminan et al., 2019). Eighty-five percent of cases are due to intracranial aneurysms. The mean age of those affected is 55 years, and two-thirds of the patients are female. The prognosis is related mainly to the neurologic condition after the subarachnoid hemorrhage and the age of the patient. Overall, 15% of patients die before reaching the hospital, another 20% die within 30 days, and overall 75% are dead or remain disabled. Case fatality has declined by 17% over the last 3 decades. Despite the improvement in outcome probably due to improved diagnosis, early aneurysm repair, administration of nimodipine, and advanced intensive care support, the outcome is not very good. Even among survivors, 75% have permanent cognitive deficits, mood disorders, fatigue, inability to return to work, and executive dysfunction and are often unable to return to their premorbid level of functioning. The key diagnostic test is computed tomography, and the treatments that are most strongly supported by scientific evidence are to undertake aneurysm repair in a timely fashion by endovascular coiling rather than neurosurgical clipping when feasible and to administer enteral nimodipine. The most common complications are aneurysm rebleeding, hydrocephalus, delayed cerebral ischemia, and medical complications (fever, anemia, and hyperglycemia). Management also probably is optimized by neurologic intensive care units and multidisciplinary teams.

Utility of the Hijdra Sum Score in Predicting Risk of Aneurysm in Patients With Subarachnoid Hemorrhage: A Single-Center Experience With 550 Patients

BACKGROUND

Subarachnoid hemorrhage (SAH) is most commonly caused by a ruptured vascular lesion. A significant number of patients presenting with SAH have no identifiable cause despite extensive cerebrovascular imaging at presentation. Significant neurological morbidity or mortality can result from misdiagnosis of aneurysm.

OBJECTIVE

To generate a model to assist in predicting the risk of aneurysm in this patient population.

METHODS

We conducted a retrospective study of all patients aged ≥18 yr admitted to a single center from March 2008 to March 2018 with nontraumatic SAH (n = 550). Patient information was compared between those with and without aneurysm to identify potential predictors. Odds ratios obtained from a logistic regression model were converted into scores which were summed and tested for predictive ability.

RESULTS

Female sex, higher modified Fisher or Hijdra score, nonperimesencephalic location, presence of intracerebral hemorrhage, World Federation of Neurosurgical Societies (WFNS) score ≥3, need for cerebrospinal fluid diversion on admission, and history of tobacco use were all entered into multivariable analysis. Greater modified Fisher, greater Hijdra score, WFNS ≥3, and hydrocephalus present on admission were significantly associated with the presence of an aneurysm. A model based on the Hijdra score and SAH location was generated and validated.

CONCLUSION

We show for the first time that the Hijdra score, in addition to other factors, may assist in identifying patients at risk for aneurysm on cerebrovascular imaging. A simple scoring tool based on patient sex, SAH location, and SAH burden can assist in predicting the presence of an aneurysm in patients with nontraumatic SAH.

AH, R. PA. The Yield of Repeat Angiography in Angiography-Negative Spontaneous Subarachnoid Hemorrhage

Objective  Despite the technological advancement in imaging, digital subtraction angiography (DSA) remains gold standard imaging modality for spontaneous subarachnoid hemorrhage (SAH). But even after DSA, around 15% of SAH remains elusive for the cause of the bleed. This is an institutional review to solve the mystery, “when is second DSA really indicated?”

Methods  In a retrospective review from January 2015 to December 2017, we evaluated cases of spontaneous SAH with initial negative DSA with repeat DSA after 6 weeks to rule out vascular abnormality. The spontaneous SAH was confirmed on noncontrast computed tomography (NCCT) and divided into two groups of perimesencephalic SAH (PM-SAH) or nonperimesencephalic SAH (nPM-SAH). The outcome was assessed by a modified Rankin’s score (mRS) at 6 months postictus.

Results  During the study period, we had 119 cases of initial negative DSA and 98 cases (82.3%) underwent repeat DSA after 6 weeks interval. A total of 53 cases (54.1%) had PM-SAH and 45 cases (45.9%) had nPM-SAH. Repeat DSA after 6 weeks showed no vascular abnormality in 53 cases of PM-SAH and in 2 (4.4%) out of 45 cases of nPM-SAH. At 6 months postictus, all cases of PM-SAH and 93% of nPM-SAH had mRS of 0.

Conclusion  We recommend, a repeat DSA is definitely not required in PM-SAH, but it should be done for all cases of nPM-SAH, before labeling them as nonaneurysmal SAH. Although the overall outcome for nonaneurysmal spontaneous SAH is better than aneurysmal SAH, nPM-SAH has poorer eventual outcome compared to PM-SAH.

Subarachnoid haemorrhage with negative initial neurovascular imaging: a systematic review and meta-analysis

Background

In patients with spontaneous subarachnoid haemorrhage (SAH), a vascular cause for the bleed is not always found on initial investigations. This study aimed to systematically evaluate the delayed investigation strategies and clinical outcomes in these cases, often described as “non-aneurysmal” SAH (naSAH).

Methods

A systematic review was performed in concordance with the PRISMA checklist. Pooled proportions of primary outcome measures were estimated using a random-effects model.

Results

Fifty-eight studies were included (4473 patients). The cohort was split into perimesencephalic naSAH (PnaSAH) (49.9%), non-PnaSAH (44.7%) and radiologically negative SAH identified on lumbar puncture (5.4%). The commonest initial vascular imaging modality was digital subtraction angiography. A vascular abnormality was identified during delayed investigation in 3.9% [95% CI 1.9–6.6]. There was no uniform strategy for the timing or modality of delayed investigations. The pooled proportion of a favourable modified Rankin scale outcome (0–2) at 3–6 months following diagnosis was 92.0% [95% CI 86.0–96.5]. Complications included re-bleeding (3.1% [95% CI 1.5–5.2]), hydrocephalus (16.0% [95% CI 11.2–21.4]), vasospasm (9.6% [95% CI 6.5–13.3]) and seizure (3.5% [95% CI 1.7–5.8]). Stratified by bleeding pattern, we demonstrate a higher rate of delayed diagnoses (13.6% [95% CI 7.4–21.3]), lower proportion of favourable functional outcome (87.2% [95% CI 80.1–92.9]) and higher risk of complications for non-PnaSAH patients.

Conclusion

This study highlights the heterogeneity in delayed investigations and outcomes for patients with naSAH, which may be influenced by the initial pattern of bleeding. Further multi-centre prospective studies are required to clarify optimal tailored management strategies for this heterogeneous group of patients.

Electronic supplementary material

The online version of this article (10.1007/s00701-019-04025-w) contains supplementary material, which is available to authorized users.

[The role of interventional neuroradiology in treatment of hemorrhagic stroke]

Treatment of hemorrhagic strokes necessitates hospitalization in an accommodated hospital offering the possibility of a multidisciplinary approach. In this setting, over recent years interventional radiology has become increasingly important from the diagnostic as well as the therapeutic standpoint. In the context of subarachnoid hemorrhage by intracranial aneurysm rupture, the NICE (National Institute for Health and Clinical Excellence) and ASA (American Stroke Academy) recommendations suggest that endovascular coiling should be considered as an alternative to surgical clipping (class I, level of evidence B). As stenting is associated with increased morbidity and mortality in the ruptured aneurysms, it should be avoided (class III, level of evidence C). The patient's clinical status on presentation should be taken into account when deciding on therapeutic management and determining prognosis. Long-term clinical outcome depends on several factors: clinical status on arrival, comorbidities, age, occurrence of operative complications and complications of subarachnoid hemorrhage such as hydrocephaly, vasospasm and delayed cerebral ischemia, as well as complications stemming from prolonged bed rest. In the event of vasospasm refractory to maximal medical therapy, endovascular treatment by intra-arterial injection of Nimodipine and angioplasty can be envisioned. In the event of intracerebral hemorrhage (ICH) by rupture cerebral dural arteriovenous fistula, once the diagnosis has been confirmed, and given the exceedingly high risk of rebleeding, first-line treatment will consist in emergency endovascular embolization. In the event of intracerebral hemorrhage (ICH) by arteriovenous rupture, treatment is decided on during a multidisciplinary meeting and either carried out immediately or delayed according to several factors: clinical conditions, age of the patient, angioarchitecture and ICH location.

Clinical complications and outcomes of angiographically negative subarachnoid hemorrhage

OBJECTIVE

To define the in-hospital course, complications, short- and long-term functional outcomes of patients with angiographically negative subarachnoid hemorrhage (anSAH), particularly those with aneurysmal-pattern anSAH (aanSAH).

METHODS

Retrospective cohort study of patients with aneurysmal subarachnoid hemorrhage (aSAH), aanSAH, and perimesencephalic-pattern anSAH (panSAH) treated at a single tertiary referral center between January 2006 and April 2018. Ninety-nine patients with anSAH (33 aanSAH and 66 panSAH) and 464 patients with aSAH were included in this study. Outcomes included symptomatic hydrocephalus requiring CSF drainage, need for ventriculoperitoneal shunt, radiographic vasospasm, delayed cerebral ischemia (DCI), radiographic infarction, disability level within 1 year of ictus, and at last clinical follow-up as defined by the modified Rankin Scale.

RESULTS

Patients with aanSAH and panSAH had similar rates of DCI and radiologic infarction, and patients with aanSAH had significantly lower rates compared to aSAH (p ≤ 0.018). Patients with aanSAH were more likely than those with panSAH to require temporary CSF diversion and ventriculoperitoneal shunt (p ≤ 0.03), with similar rates to those seen in aSAH. Only one patient with anSAH died in the hospital. Compared to those with aSAH, patients with aanSAH were significantly less likely to have a poor functional outcome within 1 year of ictus (odds ratio 0.26, 95% confidence interval 0.090-0.75) and at last follow-up (hazard ratio 0.30, 95% confidence interval 0.19-0.49, p = 0.002).

CONCLUSIONS

DCI is very uncommon in anSAH, but patients with aanSAH have a similar need for short- and long-term CSF diversion to patients with aSAH. Nevertheless, patients with aanSAH have significantly better short- and long-term outcomes.

Meta-analysis of recent literature on utility of follow-up imaging in isolated perimesencephalic hemorrhage

OBJECTIVES

Isolated perimesencephalic subarachnoid hemorrhage is an uncommon, distinct subtype of subarachnoid hemorrhage with a more benign prognosis. A negative computed tomographic angiogram has been shown to be reliable in excluding aneurysmal rupture as the underlying etiology. However, some studies continue advocating for more imaging to determine a vascular cause in perimesencephalic subarachnoid hemorrhage. The objective of this study is to evaluate the evidence for use and utility of repeat angiographic imaging after a negative computed tomographic angiogram in patients with perimesencephalic subarachnoid hemorrhage.

PATIENTS AND METHODS

Retrospective institutional analysis of patients with perimesencephalic subarachnoid hemorrhage was performed from 2014 to 2017 for number and types of follow-up angiographic imaging studies performed. Updated meta-analysis of literature was performed from 2014 onwards to assess the utility of follow-up imaging after a negative initial angiographic study.

RESULTS

The institutional review revealed no utility of additional imaging after a negative computed tomographic angiogram in 6 patients with isolated perimesencephalic subarachnoid hemorrhage. Literature review and metaanalysis of 13 studies with 588 patients revealed a vascular etiology in 3 patients with isolated perimesencephalic subarachnoid hemorrhage from a single study- 2 aneurysms and 1 patient with vasculitis.

CONCLUSIONS

Use of repeat angiographic imaging after a negative computed tomographic angiogram for perimesencephalic subarachnoid hemorrhage patients remains not uncommon, despite previous meta-analysis. Review of the more recent literature is consistent with previously published meta-analysis and shows limited benefits despite frequent use. In patients with a strictly defined perimesencephalic subarachnoid hemorrhage pattern and clinical picture consistent with perimesencephalic subarachnoid hemorrhage, an initial negative computed tomographic angiogram should be adequate and repeated follow-up studies can be avoided.

Cerebral Vasospasm-Dependent and Cerebral Vasospasm-Independent Cerebral Infarctions Predict Outcome After Nonaneurysmal Subarachnoid Hemorrhage: A Single-Center Series with 250 Patients

OBJECTIVE

The number of patients with nonaneurysmal subarachnoid hemorrhage (naSAH) has increased during the last decade. Data regarding infarctions in naSAH are still limited. The aim of this study was to identify the rate of cerebral vasospasm (CVS)-dependent and CVS-independent infarctions and their influence on clinical outcomes.

METHODS

Between 1999 and 2015, 250 patients suffering from naSAH were analyzed retrospectively. A delayed infarction was analyzed whether it was associated with CVS (CVS-dependent infarction) or not (CVS-independent).

RESULTS

A total of 36 patients (14%) had cerebral infarctions. CVS was detected in 54 patients (22%), and 15 (6%) of them developed infarctions (CVS-dependent). Infarctions without signs of CVS (CVS-independent) occurred in 21 patients (8%). Overall, 86% of the patients had favorable outcome. Patients without cerebral infarctions had the best outcome (91% favorable outcome, 5% mortality rate). Patients with CVS-independent infarctions (57%) as well as patients with CVS-dependent infarctions (53%) had a favorable outcome less often. The mortality rate was also significantly greater in patients with CVS-independent (19%) and CVS-dependent infarctions (33%). A further independent predictor was anticoagulative therapy, which increased during study period and was associated with nonperimesencephalic blood distribution.

CONCLUSIONS

CVS-dependent and independent infarctions occur in naSAH and contribute to unfavorable outcomes. Whereas CVS-independent infarctions occur in any subgroup, CVS-dependent infarctions seem to be associated with blood pattern (Fisher 3). Anticoagulative therapy seems to be not only a predictor for worse outcome but also for nonperimesencephalic SAH. Accordingly, the proportion of perimesencephalic and nonperimesencephalic SAH changed during the study period (from 2.2:1 to 1:1.7).

Basilar artery vasospasm after pretuncal non-aneurysmal subarachnoid hemorrhage responding to milrinone

Pretruncal (perimesencephalic) non-aneurysmal subarachnoid hemorrhage (PNSAH) is uniformly associated with an excellent outcome. Although cerebral vasospasm remains a common complication of SAH and constitutes an important predictor of outcome, in the setting of PNSAH, it is extremely rare. Preturnal non-aneurysmal subarac refers to a subset of SAH patients with a characteristic pattern of localized blood on CT of the head, normal cerebral angiography, and benign course when compared to the aneurysmal SAH population. The presence of radiological or even clinical vasospasm does not exclude the diagnosis of PNSAH. To our knowledge, this is the first case of symptomatic cerebral vasospasm due to PNSAH that responded to milrinone.

Relationship between venous drainage subtypes and sub-arachnoid hemorrhage subtypes: a meta-analysis

BACKGROUND

To investigate whether associations exist between venous drainage subtypes (types I, II, and III) and the risk of subarachnoid hemorrhage subtypes.

METHODS

Published case-control and case series from 2010 to 2014 which met all the inclusion criteria for the meta-analysis were selected and subjected to rigorous statistical analysis.

RESULTS

A total of 11 studies with an overall patient population (case and controls) of 891 were involved in the study. Types I and II venous drainage had odds against peri-mesencephalic subarachnoid hemorrhage. The odds were in favor of type III venous drainage and peri-mesencephalic sub-arachnoid hemorrhage and idiopathic sub-arachnoid hemorrhage (ISAH).

CONCLUSIONS

Type I deep venous drainage may not be associated with the risks of peri-mesencephalic subarachnoid hemorrhage and ISAH, however, types II and III may be associated with high risk of peri-mesencephalic subarachnoid hemorrhage and ISAH, respectively.

Nonaneurysmal Perimesencephalic Hemorrhage Is Associated with Deep Cerebral Venous Drainage Anomalies: A Systematic Literature Review and Meta-Analysis

BACKGROUND AND PURPOSE

Mechanisms underlying bleeding in nonaneurysmal perimesencephalic SAH remain unclear. Previous investigators have suggested a relationship between nonaneurysmal perimesencephalic SAH and primitive venous drainage of the basal vein of Rosenthal. We performed a meta-analysis to evaluate the relation between primitive basal vein of Rosenthal drainage and nonaneurysmal perimesencephalic SAH.

MATERIALS AND METHODS

We performed a comprehensive literature search of all studies examining the prevalence of primitive basal vein of Rosenthal drainage in patients with aneurysmal SAH and nonaneurysmal perimesencephalic SAH. Data collected were primitive basal vein of Rosenthal drainage (direct connection of perimesencephalic veins into the dural sinuses instead of the Galenic system) in at least 1 cerebral hemisphere, normal bilateral basal vein of Rosenthal drainage systems, and the number of overall primitive venous systems in the nonaneurysmal perimesencephalic SAH and aneurysmal SAH groups. Statistical analysis was performed by using a random-effects meta-analysis.

RESULTS

Eight studies with 888 patients (334 with nonaneurysmal perimesencephalic SAH and 554 with aneurysmal SAH) and 1657 individual venous systems were included. Patients with nonaneurysmal perimesencephalic SAH were more likely to have a primitive basal vein of Rosenthal drainage in at least 1 hemisphere (47.7% versus 22.1%; OR, 3.31; 95% CI, 2.15-5.08; P < .01) and were less likely to have bilateral normal basal vein of Rosenthal drainage systems than patients with aneurysmal SAH (18.3% versus 37.4%; OR, 0.27; 95% CI, 0.14-0.52; P < .01). When we considered individual venous systems, there were higher rates of primitive venous systems in patients with nonaneurysmal perimesencephalic SAH than in patients with aneurysmal SAH (34.9% versus 15.3%; OR, 3.90; 95% CI, 2.37-6.43; P < .01).

CONCLUSIONS

Patients with nonaneurysmal perimesencephalic SAH have a higher prevalence of primitive basal vein of Rosenthal drainage in at least 1 hemisphere than patients with aneurysmal SAH. This finding suggests a venous origin of some nonaneurysmal perimesencephalic SAHs. A primitive basal vein of Rosenthal pattern is an imaging finding that has the potential to facilitate the diagnosis of nonaneurysmal perimesencephalic SAH.

Should Patients Be Counseled About Possible Recurrence of Perimesencephalic Subarachnoid Hemorrhage?

BACKGROUND

Isolated perimesencephalic subarachnoid hemorrhage (pSAH) is a distinct subtype of subarachnoid hemorrhage (SAH) seen in 5% of patients with SAH, with a relatively benign natural course and good outcome compared with diffuse, aneurysmal SAH. Traditionally, the prognosis of pSAH is believed to be excellent compared with aneurysmal SAH, with no risk of recurrent hemorrhage after long-term follow-up. We describe a case of pSAH in which the patient had a recurrent perimesencephalic bleed 8 years after the initial episode. There are 5 previous reports of recurrent pSAH in existing literature.

CASE REPORT

A patient in sixth decade of life with no history of trauma presented in 2006 with acute-onset, severe headache, and "off-balance" gait. The patient was diagnosed with pSAH on the basis of computed tomography angiography and digital subtraction angiography. The patient was discharged, and follow-up computed tomography angiography over the next 2 years revealed no underlying vascular anomaly. The patient presented in 2014 with sudden onset of headache, similar to the previous episode with no new neurologic signs. Patient had repeated imaging over the succeeding 2 years, which were all negative for new blood or source of subarachnoid bleed.

REVIEW AND DISCUSSION

There are only a couple of case reports of recurrent pSAH, some of which were defined questionably. We review the reported cases and discuss the imaging results and outcome. Considering the rarity, low risks of complications, as well as the good outcome even after recurrence, we do not recommend routinely counseling patients about possibility of recurrence of pSAH.

Sexual activity as a trigger for intracranial hemorrhage

BACKGROUND

Intracranial hemorrhage (ICH) has been reported in association with sexual activity. A case-series of patients with ICH following sexual activity is presented to further elucidate the role of the physiologic sexual response as a trigger of ICH.

METHOD

A retrospective review of the medical record was performed, identifying patients presenting with ICH temporally related to sexual activity. Clinical and radiographic data were collected and reported.

RESULTS

Sixteen patients presented with non-traumatic ICH temporally related to sexual activity. Eight (50 %) patients presented with aneurysmal subarachnoid hemorrhage, four (25 %) with angiogram-negative subarachnoid hemorrhage, two (12.5 %) with a ruptured arteriovenous malformation, and two (12.5 %) with an intracerebral basal ganglia hemorrhage. Overall average age was 49.9 (range, 28-74) years. Sexual activity involved male-female intercourse in 14 (87.5 %) patients and masturbation in 2 (12.5 %) patients.

CONCLUSIONS

Sexual-activity-related ICH is rare and includes various etiologies. The human sexual response in associated with dramatic increases in arterial blood pressure, which likely underlies the association.

Natural history and treatment of craniocervical junction dural arteriovenous fistulas

Dural arteriovenous fistulas (DAVFs) located at the craniocervical junction are rare vascular malformations with distinctive features, and their natural history and the optimal treatment strategy remains unclear. We retrospectively reviewed eight patients with craniocervical junction DAVF who were evaluated at our institution between 2009 and 2012. We also conducted a MEDLINE search for all reports of craniocervical junction DAVF between 1970 and 2013, and reviewed 119 patients from 56 studies. From a total of 127 patients, 46 (37.1%) presented with myelopathy, 53 (43.1%) with subarachnoid hemorrhage (SAH), and four (3.3%) with brainstem dysfunction. SAH was typically mild, most often Hunt and Hess Grade I or II (83.3%), and associated with ascending venous drainage via the intracranial veins (p<0.001). Higher rates of obliteration were observed after microsurgery compared to embolization. Overall, younger age (odds ratio [OR] 1.07; 95% confidence interval [CI] 1.01-1.12; p=0.011), hemorrhagic presentation (OR 0.17; 95% CI 0.06-0.50; p=0.001), and microsurgery (OR 0.23; 95% CI 0.08-0.6; p=0.004) were independently predictive of good outcome at the last follow-up. Microsurgery was the only independent predictor of overall improvement at the last follow-up (OR 4.35; 95% CI 1.44-13.2; p=0.009). Prompt diagnosis and microsurgical management, offering a greater chance of immediate obliteration, may optimize the outcomes for patients with craniocervical junction DAVF. Endovascular treatment is often not feasible due to lesion angioarchitecture, and is associated with a higher risk of lesion recanalization or recurrence. However, long term studies with newer embolic agents such as Onyx (ev3 Endovascular, Plymouth, MN, USA) are yet to be performed.

Evaluation of an anatomic definition of non-aneurysmal perimesencephalic subarachnhoid hemorrhage

Background and purpose

Perimesencephalic subarachnoid hemorrhage (PSAH) is not consistently defined in the existing literature. The purpose of this study was to test the inter-observer variability and specificity for non-aneurysmal subarachnoid hemorrhage (SAH) of an anatomic definition of PSAH.

Methods

Medical records of all patients who underwent catheter angiography for evaluation of non-traumatic SAH between July 2002 and April 2012 were reviewed. Patients with anterior circulation aneurysms were excluded. Three blinded reviewers assessed whether each admission CT scan met the following anatomic criteria for PSAH: (1) center of bleeding located immediately anterior and in contact with the brainstem in the prepontine, interpeduncular, or posterior suprasellar cistern; (2) blood limited to the prepontine, interpeduncular, suprasellar, crural, ambient, and/or quadrigeminal cisterns and/or cisterna magna; (3) no extension of blood into the Sylvian or interhemispheric fissures; (4) intraventricular blood limited to incomplete filling of the fourth ventricle and occipital horns of the lateral ventricles (ie, consistent with reflux); (5) no intraparenchymal blood.

Results

56 patients with non-aneurysmal SAH and 50 patients with posterior circulation or posterior communicating artery aneurysms were identified. Seventeen (16%) of the 106 admission CT scans met the anatomic criteria for PSAH. No aneurysm was identified in this subgroup. Inter-observer agreement was excellent with κ scores of 0.89–0.96 and disagreement in 2.8% (3/106) of cases.

Conclusions

Our anatomic definition of PSAH correlated with a low risk of brain aneurysm and was applied with excellent inter-observer agreement.

Use of Follow-Up Imaging in Isolated Perimesencephalic Subarachnoid Hemorrhage

Background and Purpose—

Multiple studies have shown that negative computed tomographic angiograms (CTAs) are reliable in excluding aneurysms in patients with isolated perimesencephalic subarachnoid hemorrhage (pSAH). We evaluate the use of digital subtraction angiography versus CTA for initial diagnosis and of angiographic follow-ups in patients with pSAH by performing an institutional analysis and a meta-analysis of literature.

Methods—

Retrospective institutional analysis of patients with pSAH was performed from 2008 to 2014. The number and types of follow-up imaging studies were tabulated. Initial and follow-up studies were evaluated by an experienced neuroradiologist for intracranial aneurysm. Meta-analysis of literature was performed to assess the use of initial digital subtraction angiography and of follow-up imaging.

Results—

Our institutional review revealed no additional use of initial digital subtraction angiography or of any angiographic follow-up after initial negative CTA in patients with pSAH on noncontrast CT. Meta-analysis of 40 studies yielded a total of 1031 patients. Only 8 aneurysms were first diagnosed on follow-ups (0.78%). Careful review showed that some of these aneurysms reported on follow-up are of questionable validity. Initial digital subtraction angiography and follow-up imaging after a negative initial CTA showed no statistically significant benefits.

Conclusions—

In patients meeting the strict imaging criteria of pSAH, initial negative CTA is reliable in excluding aneurysms. A critical review of the literature through meta-analysis shows no foundation for multiple follow-up studies in patients with pSAH.

Clinical outcome and prognostic factors of patients with angiogram-negative and non-perimesencephalic subarachnoid hemorrhage: benign prognosis like perimesencephalic SAH or same risk as aneurysmal SAH?

Subarachnoid hemorrhage (SAH) is usually caused by a ruptured intracranial aneurysm. However, in some patients, no source of hemorrhage might be detected despite repeated digital subtraction angiography (DSA). Our objective was to analyze factors influencing the clinical outcome in patients suffering from non-aneurysmal and non-perimesencephalic (NPM) SAH. Between 1999 and 2011, 68 of 1,188 patients with SAH (5.7%) suffered from non-aneurysmal and NPM-SAH. Outcome was assessed according to the modified Rankin Scale (mRS) at 6 months (mRS 0-2 favorable vs. 3-6 unfavorable). In patients with angiogram-negative and NPM-SAH, favorable outcome was achieved in 56 patients (82.4%). In the multivariate analysis, age <65 years and non-Fisher 3 bleeding pattern were significantly associated with favorable outcome. Angiogram-negative and NPM-SAH had good prognoses. Patients with non-Fisher-type 3 bleeding had excellent outcomes similar to patients with perimesencephalic SAH, but patients with Fisher-type 3 bleeding were at risk for poor outcome like aneurysmal SAH patients due to cerebral vasospasm and delayed cerebral ischemia. Age and bleeding type were detected as prognostic factors in the multivariate analysis.

De novo aneurysm of the anterior communicating artery presenting with subarachnoid hemorrhage 7 years after initial cryptogenic subarachnoid hemorrhage: a case report and review of the literature

Spontaneous subarachnoid hemorrhage (SAH) is usually caused by a ruptured cerebral aneurysm. Despite the use of initial four-vessel cerebral digital subtraction angiography (DSA), 15 % of all cases remain idiopathic. According to the initial computed tomographic scan, the spontaneous SAH can be divided into a perimesencephalic group associated with a benign nature and a nonperimesencephalic group with a similar clinical course as aneurysmal SAH. We present a case of a 49-year-old man with a de novo aneurysm formation of the anterior communicating artery with SAH 7 years after initial cryptogenic nonperimesencephalic SAH. This observation suggests that in some cases, long-term angiographic studies might be justified.

Subarachnoid hemorrhage of unknown etiology along the cortical convexity

BACKGROUND

Only 8% to 22% of cases of subarachnoid hemorrhage (SAH) are of nonaneurysmal origin. Among these, perimesencephalic nonaneurysmal SAH is a distinct clinical and radiologic entity with normal angiographic findings and a good prognosis. In contrast, SAH of nonaneurysmal origin occurring along the cortical convexity is rare and poorly understood. We report 2 cases of subarachnoid hemorrhage along the cortical convexity and discuss their possible etiologies.

METHODS

In a retrospective analysis of 234 patients with SAH, we identified 2 patients with a typical computed tomographic pattern of convexity SAH that was associated with no known etiology.

RESULTS

In these 2 cases, the source of hemorrhage could not be identified with computed tomography, magnetic resonance imaging, or digital subtraction angiography, although neurovascular outcomes were good. The patients reported such incidents as coughing or exertion immediately before headache developed. These incidents may have caused increased intracranial pressure.

CONCLUSION

We suggest the possible involvement of a brief increase in intracranial pressure, such as that accompanying coughing or exertion, in the occurrence of SAH along the cortical convexity.

Endoscopic third ventriculostomy for hydrocephalus after perimesencephalic subarachnoid hemorrhage: initial experience in three patients

BACKGROUND

To review the outcome after endoscopic third ventriculostomy (ETV) for symptomatic, persistent hydrocephalus in three patients with perimesencephalic angiographically negative subarachnoid hemorrhage (PNH) who were dependent on an external ventricular drain (EVD).

METHODS

All patients initially presented with severe headache, nuchal rigidity, confusion and lethargy (Hunt-Hess Grade II or III), and persistent, EVD-dependent hydrocephalus. Cranial CT images in each revealed acute hydrocephalus and perimesencephalic hemorrhage pattern with a heavy clot burden (Fisher grade 3). A 3D-CT angiogram on admission and two four-vessel cerebral angiograms failed to demonstrate a bleeding source. All three patients failed trial EVD clamping, with clinical deterioration and elevated intracranial pressure (ICP). ETV was performed with a 0-degree endoscope in a 4.6-mm irrigating sheath using an endoscopic-coring/"cookie-cut" technique. An EVD was left in place for postoperative ICP monitoring but was clamped.

RESULTS

ETV was accomplished in all patients. In one case, a tiny basilar tip aneurysm was seen during the endoscopic procedure. Intraoperatively, the prepontine cistern revealed dense, degraded blood products. Postprocedure ICP measurements were reduced to normal range. Clinical improvement, normal ICP readings, and/or radiographic evidence of resolution of hydrocephalus allowed uneventful removal of the EVD within 36-48 h post-ETV in all patients. All remained headache-free, with a normal neurological examination, during a follow-up period of 10, 11, and 12 months, respectively.

CONCLUSION

To our knowledge, this is the first report of ETV for PNH with hydrocephalus and the first report of a basilar tip microaneurysm seen intraoperatively during ETV. ETV is a viable treatment option for refractory hydrocephalus secondary to a perimesencephalic pattern of subarachnoid hemorrhage (SAH). Its early application can avoid placement of a ventriculoperitoneal shunt, curtail the extended use of an EVD, and reduce the associated infection risks. Despite thorough angiographic investigation for an aneurysmal cause of SAH, a "microaneurysm" of the basilar artery was found at ETV. No complication or rebleeding was encountered.

Non-aneurysmal perimesencephalic subarachnoid hemorrhage caused by a cavernous angioma

BACKGROUND

Cavernous angiomas are responsible for intracranial hemorrhages, but bleeding is infrequently confined to the subarachnoid space.

METHODS

We describe an elderly, yet healthy man who sought medical attention for subarachnoid hemorrhage.

RESULTS

Vascular imaging failed to reveal a cerebral aneurysm, however magnetic resonance imaging done late in the course showed a cavernous angioma, on the surface of the left upper cerebellar peduncle, that had bled.

CONCLUSIONS

The so-called "angiography-negative" subarachnoid hemorrhage could have its source in small cavernous angiomas lying on the surface of basal skull brain structures.

Cerebral aneurysm exclusion by CT angiography based on subarachnoid hemorrhage pattern: a retrospective study

Background

To identify patients with spontaneous subarachnoid hemorrhage for whom CT angiography alone can exclude ruptured aneurysms.

Methods

An observational retrospective review was carried out of all consecutive patients with non-traumatic subarachnoid hemorrhage who underwent both CT angiography and catheter angiography to exclude an aneurysm. CT angiography negative cases (no aneurysm) were classified according to their CT hemorrhage pattern as "aneurismal", "perimesencephalic" or as "no-hemorrhage."

Results

Two hundred and forty-one patients were included. A CT angiography aneurysm detection sensitivity and specificity of 96.4% and 96.0% were observed. All 35 cases of perimesencephalic or no-hemorrhage out of 78 CT angiography negatives also had negative angiography findings.

Conclusions

CT angiography is self-reliant to exclude ruptured aneurysms when either a perimesencephalic hemorrhage or no-hemorrhage pattern is identified on the CT within a week of symptom onset.

Thrombosis and subsequent recanalization of a ruptured intracranial aneurysm in 2 children, demonstrating the value of repeating catheter angiography after an initial negative study

The cases of 2 children with true aneurysmal subarachnoid hemorrhages (SAHs) and initial false-negative angiograms are reported. In both cases, the initial angiogram was of adequate technical quality and included the projections on which aneurysms were later documented. There was no significant vasospasm at the time of initial angiography; therefore, transient aneurysm sac thrombosis was the most likely explanation for the initial false-negative studies. It is particularly interesting to note that 1 of the 2 patients had a pattern of hemorrhage compatible with the most limited definition of a perimesencephalic SAH, that is, a small prepontine cistern hemorrhage. If a second angiogram had been deemed unnecessary based on that criterion alone, a ruptured basilar tip aneurysm would have escaped detection and treatment.

Long-term outcome and quality of life after nonaneurysmal subarachnoid hemorrhage

PURPOSE

Nonaneurysmal subarachnoid hemorrhage (SAH) is an uncommon form of SAH. As nonaneurysmal SAH is often concentrated around the pons and midbrain, the term perimesencephalic SAH (pmSAH) is widely accepted to describe this entity, though there are patients with a more widespread distribution of subarachnoid blood (non-pmSAH). The outcome of pmSAH is commonly regarded as good, although often outcome is not analyzed using standardized tools of outcome measurement. In this study we focused on the patient's quality of life after nonaneurysmal SAH.

METHODS

We included 26 patients in this study who experienced a nonaneurysmal SAH between 2003 and 2007. Neurological status upon admission as well as on discharge was recorded. All patients received a detailed postal questionnaire on their current neurological situation, dependence on care (Barthel Index), quality of life regarding their physical and psycho-social well-being (Short-form 36) and current employment situation and ability to work, respectively.

RESULTS

After 32.68 +/- 19.81 months, almost all patients achieved a Glasgow Outcome Score of 4 or 5 and a Barthel Index of more than 90, although there was a difference between patients suffering from pmSAH and patients with non-pmSAH. Physical and social functioning recovered to almost normal levels but vitality and individual health were often perceived as reduced in self-evaluation.

CONCLUSION

Nonaneurysmal SAH is a begnin entity, though there is a difference between pmSAH and non-pmSAH in outcome. Self-evaluations of vitality and individual health in both groups are often experienced as reduced, thus imposing the question of whether neurological rehabilitation should be recommended despite good neurological outcome.

Inter- and intraobserver agreement in CT characterization of nonaneurysmal perimesencephalic subarachnoid hemorrhage

BACKGROUND AND PURPOSE

The perimesencephalic pattern of SAH as seen on unenhanced CT is associated with significantly better outcomes when compared to an aneurysmal pattern of SAH. The aim of this study was to determine the degree of inter- and intraoberver agreement for characterization of the NAPH as seen on unenhanced CT.

MATERIALS AND METHODS

We retrospectively reviewed the CT scans of 37 patients with spontaneous SAH, all of whom had undergone CT within 24 hours of onset of headache symptoms. All patients had undergone conventional cerebral angiography to confirm or exclude aneurysms or other vascular pathology. All 37 cases were angiographically confirmed nonaneurysmal SAHs. Four readers with neuroradiology subspecialty training independently evaluated CT images to characterize the hemorrhage pattern as compatible with the well-described NAPH. Each reader performed a second reading session blinded to the initial readings. The first and second sets of readings were performed approximately 4 months apart. Inter- and intraobserver agreement for characterization of the NAPH was determined by using the kappa statistic.

RESULTS

Of the 37 angiographically confirmed nonaneurysmal SAHs, there was unanimous agreement as to the hemorrhage pattern in 29 (78%) cases and disagreement in 8 (22%) cases. Overall, intraobserver agreement was good (kappa = 0.80). Interobserver agreement was also good (kappa = 0.79).

CONCLUSIONS

Overall, inter- and intraobserver agreement for the NAPH was good. There was, however, a level of disagreement among observers, thus suggesting that clinicians should be cautious when deciding whether to pursue follow-up imaging.

Recurrent perimesencephalic subarachnoid hemorrhage during antithrombotic therapy

INTRODUCTION

In patients with non-aneurysmal perimesencephalic hemorrhage, spontaneous rebleeding does not occur. The lack of reported recurrences may lead to less cautious administration of antithrombotic therapy.

METHODS

Case report.

RESULTS

A 57-year-old woman with a perimesencephalic pattern of hemorrhage and negative CT angiography was treated with carbasalate calcium and intravenous heparin because of an acute coronary syndrome. Three days after installment of this antithrombotic therapy she experienced a recurrent perimesencephalic hemorrhage leading to hydrocephalus and a decrease in consciousness. She died the same day as a result of ventricular fibrillation.

CONCLUSION

In the early phase after perimesencephalic hemorrhage, anticoagulant therapy may lead to rebleeding. The risks and benefits of antithrombotic therapy should be carefully weighed in patients with a perimesencephalic pattern of hemorrhage and negative CT angiography.