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Patients with imaging findings concerning for subarachnoid hemorrhage, however, with no evidence of hemorrhage following autopsy or cerebrospinal fluid testing are diagnosed with having pseudo-subarachnoid hemorrhage. A 73-year-old female presented to the emergency department with altered mental status one day after undergoing a lumbar epidural steroid injection at an outside hospital; a noncontrast computed tomography scan of the head revealed evidence of diffuse hyperdensity within the subarachnoid space concerning for subarachnoid hemorrhage. The patient underwent magnetic resonance imaging which demonstrated diffuse opacification of the cerebrospinal fluid spaces with gadolinium and the diagnoses of pseudo-subarachnoid hemorrhage and gadolinium encephalopathy were made. The combination of the neurologic symptoms related to gadolinium encephalopathy and the radiographic findings of pseudo-subarachnoid hemorrhage can create a clinical presentation nearly identical to ruptured aneurysmal subarachnoid hemorrhage. Patient history, magnetic resonance imaging findings, and temporal changes in computed tomography provide vital tools in establishing a diagnosis of pseudo-subarachnoid hemorrhage, especially after an iatrogenic intrathecal contrast administration.

We report the case of an extended pseudo-subarachnoid hemorrhage (PSAH) related to contrast intracerebral diffusion from blood-brain barrier breakdown on periprocedural percutaneous coronary intervention right corticofrontal ischemic stroke. PSAH is a rare and complex phenomenon, and it is important to differentiate PSAH from subarachnoid hemorrhage to avoid inappropriate treatment with potentially severe consequences. (Level of Difficulty: Beginner.)

Objective To investigate the CT features and clinical significance of pseudo-subarachnoid hemorrhage sign (PSAH) with diffuse brain edema. Methods CT of 13 patients including 5 brain-dead organ donors with non-hemorrhagic disease and 8 non-traumatic critically ill patients with confirmed P-SAH from March 2019 to December 2019 was reviewed. Regions of interest (ROI) were drawn on the cerebral white matter (100 mm²) and fissure (10 mm²) symmetrically on plain CT. The CT values were measured and compared between the 2 groups. The clinical prognosis of non-traumatic critically ill patients was observed. Results On all patients, CT showed diffuse swelling of brain parenchyma, low density, blurred gray-white matter boundary, narrow ventricle under pressure, symmetrically high and linear attenuation in basal cistern and sulci. The CT values in brain death were (26.25±2.28) HU (range: 21.90- 29.8 HU) in the white matter and (41.45±2.42) HU (range: 35.1-45.0 HU) in the fissures. The CT values in non-traumatic critically ill patients were (26.02±2.20) HU (range: 21.9-29.8 HU) in the white matter and (45.07±4.47) HU (range: 35.1-56.9 HU) in the fissures. The average CT value difference of white matter and fissures in all cases were (17.54±3.05) HU. Conclusion In severe diffuse brain edema, typical P-SAH can be seen on plain CT, and the presence of P-SAH often indicates a poor prognosis. [ABSTRACT FROM AUTHOR]

Subarachnoid hemorrhage (SAH) is a severe cerebrovascular condition. Some cases present with typical signs of SAH on head computed tomography (CT), whereas other cases have a condition known as pseudo-SAH, with no bleeding actually present. In our clinical experience, we noted that cases of hyperhemoglobinemia often also had pseudo-SAH. Here we investigated the relationship between hyperhemoglobinemia and pseudo-SAH and explored the underlying mechanism. We retrospectively collected data for patients who were treated for hyperhemoglobinemia in our hospital and had available brain CT scans. An age-matched control group of patients with normal hemoglobin levels was used to compare the incidence of pseudo-SAH between individuals with elevated versus normal hemoglobin levels. Spearman correlation and logistic regression analyses were performed to identify correlations between pseudo-SAH and hemoglobin level as well as gender, history of chronic obstructive pulmonary disease, and smoking history. The incidence of pseudo-SAH was significantly higher in hyperhemoglobinemia group than in the control group (12.5% vs. 1.6%, respectively, P < 0.001), and within the hyperhemoglobinemia group, it was significantly higher among those with a hemoglobin value ≥210 g/L than among those with a hemoglobin value <210 g/L (29.2% vs. 8.8%, respectively, P < 0.001). Spearman correlation analysis and logistic regression analysis showed a significant correlation between pseudo-SAH and hyperhemoglobinemia but no significant correlation between pseudo-SAH and gender, COPD, or smoking history. Hyperhemoglobinemia may be a contributing factor to pseudo-SAH. Clinicians should be aware of this phenomenon and be careful to distinguish pseudo-SAH from SAH, particularly in patients with hyperhemoglobinemia. • Hyperhemoglobinemia may be a contributing factor to pseudo-SAH. • We analyzed the incidence of pseudo-SAH in hyperhemoglobinemia patients. • We retrospectively analyzed pseudo-SAH on CT associated with hyperhemoglobinemia. [ABSTRACT FROM AUTHOR]

Background: Acute aneurysmal subarachnoid hemorrhage (SAH) is a medical and neurosurgical emergency from ruptured brain aneurysm. Aneurysmal SAH is identified on brain computed tomography (CT) as increased density of basal cisterns and subarachnoid spaces from acute blood products. Aneurysmal SAH-like pattern on CT appears as an optical illusion effect of hypodense brain parenchyma and/or hyperdense surrounding cerebral cisterns and blood vessels termed as "pseudo-subarachnoid hemorrhage" (pseudo-SAH).Methods: We reviewed clinical, laboratory, and radiographic data of all SAH diagnoses between January 2013 and January 2018, and found subsets of nonaneurysmal SAH, originally suspected to be aneurysmal in origin. We performed a National Library of Medicine search methodology using terms "subarachnoid hemorrhage," "pseudo," and "non-aneurysmal subarachnoid hemorrhage" singly and in combination to understand the sensitivity, specificity, and precision of pseudo-SAH.Results: Over 5 years, 230 SAH cases were referred to our tertiary academic center and only 7 (3%) met the definition of pseudo-SAH. Searching the National Library of Medicine using subarachnoid hemorrhage yielded 27,402 results. When subarachnoid hemorrhage and pseudo were combined, this yielded 70 results and sensitivity was 50% (n = 35). Similarly, search precision was relatively low (26%) as only 18 results fit the clinical description similar to the 7 cases discussed in our series.Conclusions: Aneurysmal SAH pattern on CT is distinct from nonaneurysmal and pseudo-SAH patterns. The origin of pseudo-SAH terminology appears mostly tied to comatose cardiac arrest patients with diffuse dark brain Hounsfield units and cerebral edema, and is a potential imaging pitfall in acute medical decision-making. [ABSTRACT FROM AUTHOR]

Background: On rare occasions, cisterns are demonstrated as high-density areas on computed tomography (CT) and misdiagnosed with subarachnoid hemorrhage (SAH). This false-positive finding is called pseudo-SAH. Patients and Methods: From April 2014 to August 2018, a total of 161 patients with chronic subdural hematoma (CSDH) were treated in our hospital. For these cases, the existence of a pseudo-SAH sign on CT was retrospectively examined. Results: One patient with bilateral CSDH showed pseudo-SAH and a further examination to evaluate vascular abnormalities causing true SAH was necessary. In three patients, the Sylvian fissures were demonstrated as high-density areas due to an atherosclerotic middle cerebral artery; however, the condition was not misdiagnosed with SAH. Conclusion: In cases of CSDH, there is a possibility that CT demonstrates a pseudo-SAH sign. In such cases, close examinations to exclude true SAH are mandatory. [ABSTRACT FROM AUTHOR]

The article highlights various pseudo subarachnoid hemorrhage (SAH) features on computed tomographies (CT), which may lead to unnecessary testing. During tuberculous meningitis, there is breakage of brain-blood barrier, leading to leakage of a proteinaceous material and increased CT attenuation. It mentions that cerebral infarction may cause mimic SAH. It reports appearance of pseudo SAH in Intracranial Hypotension patients, with orthostatic headache and low cerebrospinal fluid (CSF) pressure.

Objective: (1) To determine the frequency of CT mimics of subarachnoid hemorrhage (SAH) in a large cohort of subjects with spontaneous intracranial hypotension (SIH). (2) To emphasize the distinctive radiologic features of SIH. Patients and methods: CT scans of 95 subjects with SIH were retrieved and reviewed to search for findings of pseudo-SAH (CT mimics of SAH in the absence of blood). Results: Pseudo-SAH radiologic findings (increased attenuation in the basilar cisterns, sylvian fissures, or along the tentorium) were detected on CT scans of 10 of the 95 SIH subjects. However, on MRI scans, these subjects exhibited the typical SIH abnormalities (diffuse pachymeningeal enhancement and brain sagging with obliteration of basilar cisterns). Conclusions: In the emergency room, SIH should be considered in the differential diagnosis between SAH and pseudo-SAH. Although SIH and SAH can share some radiologic features, SIH has distinctive MRI and CT findings. Their recognition should obviate the need for more invasive procedures (e.g., cerebral angiography) to definitely rule out SAH and an aneurismal source of bleeding. [ABSTRACT FROM AUTHOR]

The article discusses a study which assessed incidence and clinical characteristics of aneurysmal subarachnoid hemorrhage-cardio-pulmonary resuscitation (SAH-CPR) patients among non-traumatic CPA-CPR patients. The researchers also investigated their therapeutic and prognostic implications. A significant difference in the overall survival between true-SAH and pseudo-SAH group was found.

We report a case of a 33-year-old woman who developed severe brain edema and pseudo-subarachnoid hemorrhage (SAH) at 36-hour follow-up after successful cardiopulmonary resuscitation for anaphylactic shock as a result of a bee sting. The patient died on the sixth day of the follow-up due to multiple organ failure and brain herniation. Our case suggests that the SAH--like findings on computed tomography scanning were not a new complication ("real" SAH) arising from the bee sting; rather, it was a pseudo-SAH related to prolonged cardiopulmonary resuscitation). [ABSTRACT FROM AUTHOR]

Subarachnoid hemorrhage (SAH) appears on CT as hyperdensity in the subarachnoid space. In rare circumstances a similar appearance may occur in the absence of subarachnoid blood, a finding that has been termed “pseudo-subarachnoid hemorrhage.” We describe three patients who presented with abrupt alterations in mental status in whom CT falsely suggested SAH, and we review the literature regarding this imaging finding. In contrast to prior reports, all three of our patients had a favorable outcome. [ABSTRACT FROM AUTHOR]

Objective: Hyperdensity in the basal cisterns on computed tomography (CT) brain scan is a diagnostic feature in subarachnoid hemorrhage. However, false enhancement of the subarachnoid space on CT scan may be seen in diffuse neurological conditions with acute presentation. This is the first reported case of a 'focal lesion' (acute cerebellar infarct) producing a 'pseudo-subarachnoid hemorrhage' secondary to increased intracranial pressure. Clinical presentation: A 42-year-old man presented with acute onset of left hemiataxia and neck pain. CT brain scan showed a left cerebellar infarct. During the admission, he had sudden onset of altered sensorium, and an emergency CT scan showed diffuse cerebral edema and hyperdensity of the basal cisterns. The patient then developed sudden cardiac arrest and all resuscitative measures failed. Autopsy showed no evidence of subarachnoid hemorrhage. Conclusion: Pseudo-subarachnoid hemorrhage is a rare clinical entity. It should be considered as a possibility in the evaluation and management of patients presenting acutely with CT brain scan showing hyperdensity of the basal cisterns and vascular imaging revealing absence of any aneurysm or vascular malformation. [ABSTRACT FROM AUTHOR]

A 49-year-old white male presented with a pseudo-subarachnoid hemorrhage and diffuse brain edema. Neuroimaging showed brain edema causing the unusual findings of a pseudo-subarachnoid hemorrhage and bilateral occipital lobe infarcts following herniation and compression of the posterior cerebral arteries. An enlarged corpus callosum was noted which led to a brain biopsy and a diagnosis of gliomatosis cerebri. [ABSTRACT FROM AUTHOR]

Spontaneous intracranial hypotension (SIH) is an important cause of headache mainly associated with spinal cerebrospinal fluid leakage. We herein report the case of a 51-year-old man who developed SIH after swimming. Brain magnetic resonance imaging (MRI) showed a transient high-intensity lesion in the splenium of the corpus callosum (SCC), in addition to bilateral subdural hematomas (SDH) and pseudo-subarachnoid hemorrhage on brain computed tomography. The splenial lesion disappeared and SDH improved after an epidural blood patch. This case emphasizes that transient SCC lesions could coexist with SIH and that SIH should be considered in the differential diagnosis of SCC lesions.

We report the case of an extended pseudo-subarachnoid hemorrhage (PSAH) related to contrast intracerebral diffusion from blood-brain barrier breakdown on periprocedural percutaneous coronary intervention right corticofrontal ischemic stroke. PSAH is a rare and complex phenomenon, and it is important to differentiate PSAH from subarachnoid hemorrhage to avoid inappropriate treatment with potentially severe consequences. ( Level of Difficulty: Beginner. )., Competing Interests: The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (© 2020 The Authors.)

Abstract: We report a 20-year-old man who suffered from severe headache. A brain CT scan revealed that he had diffuse brain swelling and increased attenuation of the basal cisterns and Sylvian fissure. Subarachnoid hemorrhage (SAH) was diagnosed but the results of CT angiography and conventional arterioangiography were negative. His headache relapsed and remitted several times during the following months. Brain MRI demonstrated brain sagging with a crowded foramen magnum. Spontaneous intracranial hypotension (SIH) was finally diagnosed and his headache subsided after application of an epidural blood patch. Pseudo-SAH on CT scan is an unusual manifestation of SIH that often results in delay of diagnosis and adequate treatment. [Copyright &y& Elsevier]

Pseudo-subarachnoid hemorrhage (PSAH) is a false-positive finding on cranial computed tomography (CT) in patients with cerebral edema. Its appearance on CT resembles subarachnoid hemorrhage despite the absence of subarachnoid blood. We report the finding of PSAH in a case of massive valproic acid overdose. [ABSTRACT FROM AUTHOR]

Purpose: Newly updated guidelines suggest brain computed tomography for out-of-hospital cardiac arrest survivors to identify a neurologic cardiac arrest cause. We hypothesized that the "pseudo-subarachnoid hemorrhage" (p-SAH) sign in cardiac arrest survivors is associated with poor outcome., Materials and Methods: We retrospectively evaluated the registries of 2 tertiary hospitals, identifying 836 adult (≥18 years) patients achieving return of spontaneous circulation after out-of-hospital cardiac arrest. Among them, 398 patients with brain computed tomography within 6 hours after return of spontaneous circulation and received targeted temperature management from 2009 to 2014 were included. Clinical characteristics and outcomes of patients with and without p-SAH were compared., Results: The prevalence of p-SAH sign was 8.0%. The p-SAH group more frequently had asystole as first rhythm and nonwitnessed arrest, predominantly resulting from asphyxia (56.3%). Targeted temperature management characteristics were not different between groups, although the p-SAH cohort had worse neurologic outcomes at discharge (100% vs 67.2%; P < .001). Pseudo-subarachnoid hemorrhage had 11.5% sensitivity, 100% specificity, 100% positive predictive value, and 32.8% negative predictive value for poor neurologic outcome., Conclusions: Pseudo-subarachnoid hemorrhage sign might be one of the simple methods to identify poor neurologic outcome early. However, further prospective studies will be needed to clarify the clinical implication of the p-SAH sign., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The authors report an unusual case of diffuse subarachnoid hemorrhage on brain computed tomography (CT) scan in a patient with post-resuscitation anoxic encephalopathy. A 42-year-old woman suffered both respiratory and cardiac arrest, associated with hypoxic encephalopathy, which occurred during a visit to our gynecology clinic. CT examination was performed the next day, which revealed a hyperdensity in the basal cisterns with a diffuse cerebral edema. Lumbar puncture was applied for diagnosis. No yellow coloration or red cells were observed in the cerebrospinal fluid. Nineteen days after treatment, the CT examination revealed features of a subarachnoid hemorrhage with a significantly increased cerebral edema. The patient died two months later. This clinical case illustrates that hypoxic encephalopathy can mimic diffuse subarachnoid hemorrhage on CT scan., (Copyright © 2015. Published by Elsevier Masson SAS.)

Objective: Aneurysmal subarachnoid hemorrhage (SAH) is a well-known cause of sudden cardio-pulmonary arrest (CPA). Even after successful cardio-pulmonary resuscitation (CPR), the prognosis of patients following an aneurysmal SAH presenting with CPA remains dismal. However, there have been anecdotal reports of good outcomes with appropriate interventions. Pseudo-SAH resulting from marked elevation of intracranial pressure (ICP) after CPR, can mimic SAH in head computed tomographic (CT) scan. Such manifestations hamper resuscitation or delay appropriate neurosurgical management. This study assessed incidence and clinical characteristics of SAH-CPR or pseudo-SAH-CPR patients among non-traumatic CPA-CPR patients, and investigated their therapeutic and prognostic implication., Methods: During the 5-year observation period, 63 non-traumatic coma patients with CT evidence of high attenuation areas in the basal cistern who suffered arrest and underwent CPR during initial resuscitation in the emergency room, were reviewed retrospectively. They were divided into two groups according to the imaging pattern: true-SAH vs. pseudo-SAH, and then true-SAH group were further divided into two groups according to the CT acquisition time: brain CT before arrest vs. brain CT after arrest. Demographic, clinical, and CT data were assessed, and the primary outcome was measured using the 30-day Glasgow Outcome Scale (GOS) score, and the final outcome was evaluated at the end of 3 months post-ictus., Results: When compared with pseudo-SAH (n=28) patients, true-SAH (n=35) patients showed a higher Hounsfield unit values in the affected area, earlier CT acquisition time before CPR, more survivors beyond 3 months (all p<0.05); however, the 30-day survival rate was not significantly different. Of the true-SAH patients, ruptured intracranial aneurysms were found in eight patients, and definite intervention was administered in four patients. When SAH patients were categorized according to the temporal relationship with CPR, the group of 24 patients undergoing CT scan before CPR showed a lower frequency of intraventricular hemorrhage, but showed a higher chance of surgical treatment and survival at 30 days and 3 months compared to the group undergoing CT scan after CPR., Conclusion: The overall survival between true-SAH and pseudo-SAH group was different significantly. Administering definite treatment for a ruptured aneurysm in instances of true SAH could save patients, albeit infrequently. A Prompt CT scan could guarantee recognition of high-density area, blood in the ventricle, and subsequent identification of the ruptured aneurysm, altogether preventing re-bleeding and warranting further systemic resuscitation., (Copyright © 2013 Elsevier B.V. All rights reserved.)