Spontaneous subarachnoid hemorrhage and negative initial vascular imaging--should further investigation depend upon the pattern of hemorrhage on the presenting CT?

Repeat Catheter Angiography in Patients with Aneurysmal-Pattern Angiographically Negative Subarachnoid Hemorrhage

BACKGROUND

A significant proportion of patients with subarachnoid hemorrhage have a normal cerebral angiogram. Patients with angiographically negative subarachnoid hemorrhage (anSAH) with either perimesencephalic- (panSAH) or aneurysmal-pattern hemorrhage (aanSAH, also known as diffuse anSAH) have an excellent prognosis, but only if underlying vascular abnormalities are completely excluded. The rate of occult aneurysms in patients with aanSAH varies widely across studies. The purpose of this study was to quantify the value of repeat DSA in these patients.

METHODS

We reviewed the records of all patients initially diagnosed with aanSAH after a screening DSA at a single tertiary neurovascular referral center from January 2006-April 2018. Patients with panSAH and traumatic SAH were excluded. We also performed a systematic review and meta-analysis of positive second DSAs in previously published case series of patients with aanSAH who underwent two serial DSAs. For meta-analysis, PubMed Central, MEDLINE and Cochrane Library databases were searched for pertinent studies up to November 2019. The rate of aneurysm detection on repeat angiography was extracted from each study. Pooled rates for positive second angiogram were calculated as untransformed proportions in a binary random-effects model meta-analysis. Inter-study heterogeneity was calculated using an I² statistic.

RESULTS

Three of 27 patients (11.1%) with aanSAH and at least two DSAs were subsequently found to have a cerebral aneurysm in our institutional dataset. Twenty-six studies in our systematic review met inclusion criteria, and the pooled rate of positive second angiogram was 10.4% (95% CI 7.3%-13.5%, P < 0.001). Substantial inter-study heterogeneity was observed in the meta-analysis (I² = 61.7%, P < 0.001).

CONCLUSIONS

One in 10 patients with aanSAH has an occult ruptured aneurysm. A second-look DSA should be strongly considered in these cases.

Subarachnoid Hemorrhage of Unknown Cause: Distribution and Role of Imaging

Subarachnoid hemorrhage of unknown cause represents approximately 10% to 15% of nontraumatic subarachnoid hemorrhages. The key factors in determining the management strategy for a presumed nonaneurysmal subarachnoid hemorrhage are the distribution, location, and amount of subarachnoid blood. Hemorrhage distribution on computed tomography can be categorized as follows: perimesencephalic, diffuse, sulcal, and primary intraventricular. The extent of the workup required in determining the cause of hemorrhage depends on the distribution of blood. The authors review the potential causes, differential diagnoses, and acute and long-term follow-up strategies in patients with subarachnoid hemorrhage of unknown cause.

CT angiogram negative perimesencephalic subarachnoid hemorrhage: is a subsequent DSA necessary? A systematic review

Background

Perimesencephalic subarachnoid hemorrhage (PMSAH) is a benign subtype with distinct clinical-radiologic features. Digital subtraction angiography (DSA) remains the gold standard investigation for exclusion of a macrovascular cause, although increasingly more clinicians rely solely on CT angiography (CTA). The primary aim of this systematic review was to evaluate the current literature regarding the negative predictive value of CTA.

Methods

A systematic search in concordance with the PRISMA checklist was performed for studies published between 2000 and 2018. Studies with ≥10 adult patients diagnosed on a non-contrast brain CT with a PMSAH, who underwent a negative CTA and were subsequently subject to a DSA, were included. Simple pooled analysis was performed to inform the negative predictive value (95% CI) of CTA and the risk of DSA- and CTA-related complications.

Results

Eighteen studies (669 patients) were included. All patients were subject to at least one DSA, the first one mostly performed within 24 hours of CTA (68.6%). 144 patients (21.5%) underwent a second DSA and a third repeat DSA was performed in one patient. The overall negative predictive value of CTA was 99.0% (95% CI 97.8% to 99.5%). The risk of complications following DSA and CTA were 1.35% (3/222) and 0% (0/41), respectively.

Conclusions

Undertaking a DSA after a negative CTA may not add any further diagnostic value in patients with PMSAH and may lead to net harm. This observation needs to be validated in a large-scale prospective multicenter study with complete case ascertainment and robust data on CTA and DSA complications.

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.

Delayed Cerebral Ischemia and Vasospasm After Spontaneous Angiogram-Negative Subarachnoid Hemorrhage: An Updated Meta-Analysis

OBJECTIVE

To report clinical outcomes of delayed cerebral ischemia (DCI) and vasospasm in angiogram-negative subarachnoid hemorrhage (SAH) according to hemorrhage patterns, perimesencephalic hemorrhage (PMH) and non-PMH.

METHODS

Online databases from January 1990 to December 2017 were systematically reviewed. A fixed-effects model was used to control heterogeneity. To resolve publication bias, the trim and fill method was used to estimate number of missing studies and adjusted odds ratio (OR). Subgroup analysis of data from studies that defined angiogram-negative subarachnoid hemorrhage by angiography repeated at least twice or computed tomography angiography was performed.

RESULTS

Among 24 studies including 2083 patients, 23/985 patients (2.3%) with PMH and 144/1098 patients (13.1%) with non-PMH had DCI, indicating that patients with PMH experienced significantly lower DCI than patients with non-PMH (OR = 0.219; 95% confidence interval [CI], 0.144-0.334). Regarding vasospasm, 99/773 patients (12.8%) with PMH and 231/922 patients (25.1%) with non-PMH exhibited vasospasm, indicating that patients with PMH experienced significantly lower vasospasm than patients with non-PMH (OR = 0.445; 95% CI, 0.337-0.589). Funnel plots show asymmetry indicating possible publication bias. After trimming 10 studies for DCI and 7 for vasospasm, the adjusted ORs remained significant between PMH and lower risks of DCI and vasospasm. Subgroup analysis of 789 patients in 8 studies showed a lower risk of DCI (OR = 0.268; 95% CI, 0.151-0.473) and vasospasm (OR = 0.346; 95% CI, 0.221-0.538) in patients with PMH.

CONCLUSIONS

PMH showed a significantly lower risk of DCI and vasospasm than non-PMH. Clinical outcomes of angiogram-negative subarachnoid hemorrhage, based on meta-analysis of individual patient data, need to be investigated.

Is there added value in obtaining cervical spine MRI in the assessment of nontraumatic angiographically negative subarachnoid hemorrhage? A retrospective study and meta-analysis of the literature

OBJECTIVE Diagnostic algorithms for nontraumatic angiographically negative subarachnoid hemorrhage (AN-SAH) vary, and the optimal method remains subject to debate. This study assessed the added value of cervical spine MRI in identifying a cause for nontraumatic AN-SAH. METHODS Consecutive patients 18 years of age or older who presented with nontraumatic SAH between February 1, 2009, and October 31, 2014, with negative cerebrovascular catheter angiography and subsequent cervical MRI were studied. Patients with intraparenchymal, subdural, or epidural hemorrhage; recent trauma; or known vascular malformations were excluded. All cervical MR images were reviewed by two blinded neuroradiologists. The diagnostic yield of cervical MRI was calculated. A literature review was conducted to identify studies reporting the diagnostic yield of cervical MRI in patients with AN-SAH. The weighted pooled estimate of diagnostic yield of cervical MRI was calculated. RESULTS For all 240 patients (mean age 53 years, 48% male), catheter angiography was performed within 4 days after admission (median 12 hours, interquartile range [IQR] 10 hours). Cervical MRI was performed within 19 days of admission (median 24 hours, IQR 10 hours). In a single patient, cervical MRI identified a source for SAH (cervical vascular malformation). Meta-analysis of 7 studies comprising 538 patients with AN-SAH produced a pooled estimate of 1.3% (95% confidence interval 0.5%-2.5%) for diagnostic yield of cervical MRI. No statistically significant between-study heterogeneity or publication bias was identified. CONCLUSIONS Cervical MRI following AN-SAH, in the absence of findings to suggest spinal etiology, has a very low diagnostic yield and is not routinely necessary.