MR diagnosis of subacute and chronic subarachnoid hemorrhage: comparison with CT

Analysis of Factors Influencing Delayed Presentation in Japanese Patients with Subarachnoid Hemorrhage

OBJECTIVE

Some aneurysmal subarachnoid hemorrhage (SAH) patients are delayed in their presentation. This can cause a washout of the subarachnoid hematoma and a potential misdiagnosis. As a result, they may suffer rerupture of the aneurysm and preventable deterioration. We investigated the factors that influence delayed SAH presentation.

METHODS

Aneurysmal SAH patients treated at 9 stroke centers from 2002 to 2020 were included. Age, gender, pre-SAH modified Rankin scale, World Federation of Neurological Surgeons grade, Fisher group, day of presentation, aneurysm treatment method, past history of cerebral stroke, comorbidity of hypertension and/or diabetes mellitus, and modified Rankin scaleat discharge were assessed retrospectively. We formed 2 groups based on the day of presentation after the onset of SAH: day 0-3 (early) and other (delayed). Logistic regression analyses detected the factors that influenced the day of presentation and outcome for SAH. A P- value <0.05 was considered significant.

RESULTS

Delayed presentation comprised 282 cases (6.3%) of 4507 included cases. Logistic regression analyses showed that patients in an urban area, of male gender, low WFNS grade and low Fisher group correlated significantly with a delayed presentation. But delayed presentation did not influence outcome at discharge.

CONCLUSIONS

Area of residency and gender correlated with delayed presentation after SAH in Japan. Urbanization, male gender, and mild SAH lead patients to delay presentation. The factors underlying these tendencies will be analyzed in a future prospective study.

Amount of blood during the subacute phase and clot clearance rate as prognostic factors for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Delayed cerebral ischemia (DCI) is a poorly predictable complication occurring after aneurysmal subarachnoid hemorrhage (SAH) that can have dramatic functional consequences. Identifying the patients with the highest risk of DCI may help to institute more suitable monitoring and therapy. Early brain injuries and aneurysm-securing procedure complications could be regarded as confounding factors leading to severity misjudgment. After an early resuscitation phase, a subacute assessment may be more relevant to integrate the intrinsic SAH severity. A retrospective analysis was performed upon patients prospectively included in the registry of SAH patients between July 2015 to April 2020. The amount of cisternal and intraventricular blood were assessed semi-quantitatively on acute and subacute CT scans performed after early resuscitation. A clot clearance rate was calculated from their comparison. The primary endpoint was the occurrence of a DCI. A total of 349 patients were included in the study; 80 (22.9%) experienced DCI. In those patients, higher Fisher grades were observed on acute (p = 0.026) and subacute (p = 0.003) CT scans. On the subacute CT scan, patients who experienced DCI had a higher amount of blood, either at the cisternal (median Hijdra sum score: 11 vs 5, p < 0.001) or intraventricular (median Graeb score: 4 vs 2, p < 0.001) level. There was a negative linear relationship between the cisternal clot clearance rate and the risk of DCI. The assessment of the amount of subarachnoid blood and clot clearance following resuscitation after aneurysmal SAH can be useful for the prediction of neurological outcome.

Magnetic resonance imaging in a guinea pig model of inner ear decompression sickness and barotrauma

OBJECTIVES/HYPOTHESIS

Scuba diving may cause severe hearing loss and vertigo due to inner ear barotrauma and decompression sickness. These may be difficult to differentiate clinically. Decompression sickness requires costly and potentially dangerous hyperbaric therapy, whereas such treatment may worsen barotrauma. The objective of this study was to assess the potential utility of magnetic resonance imaging to identify and distinguish blood from air in the inner ear, manifestations of barotrauma and decompression sickness, using a guinea pig model.

STUDY DESIGN

Prospective animal trial.

METHODS

Magnetic resonance of the head was performed at 3 Tesla, pre- and postinjection of 2, 4, or 10 μL of air or blood through the round window into the perilymph. With this model, 2 μL has been shown to cause hearing loss. Images were reviewed by a neuroradiologist blinded to the treatment.

RESULTS

All 14 normal ears, five of seven blood- and five of seven air-injected ears, were correctly interpreted. Two blood- and one air-injected ear were interpreted as indeterminate. One air-injected ear was incorrectly interpreted as blood.

CONCLUSIONS

Magnetic resonance reliably distinguishes small volumes of air and blood in the guinea pig inner ear. Magnetic resonance should be evaluated for its utility in the diagnosis of inner ear barotrauma and decompression sickness in scuba divers.

LEVEL OF EVIDENCE

NA Laryngoscope, 126:2106-2109, 2016.

Intracranial hemorrhage detection over time using susceptibility-weighted magnetic resonance imaging

BACKGROUND

The reliable detection of intracranial hemorrhages is important, but just 1 year after the hemorrhage onset it might be missed using T2-weighted spin-echo and gradient-echo sequences. Susceptibility-weighted imaging (SWI) is a new magnetic resonance imaging sequence that is extremely sensitive in hemorrhage detection and that might improve the detection of hemorrhages over time.

PURPOSE

To investigate whether the detectability of intracranial blood and its degradation products is independent of the time span after intracranial hemorrhage using SWI.

MATERIAL AND METHODS

Sixty-six consecutive patients (28 men, 38 women) with definitely known time point of intracranial hemorrhage and available SWI sequence (1.5 or 3 T) were analyzed retrospectively. Twenty-one patients had a SWI follow-up. All SWI images were assessed by two radiologists in consensus regarding hemorrhage visibility using a 5-point scale. Statistical analysis was performed using Spearman's correlation test.

RESULTS

Median time interval between hemorrhage and first available SWI measurement was 819 days (range, 0 days to 13.2 years). Nine of 66 patients had an isolated subarachnoid hemorrhage (iSAH) and were therefore analyzed separately. In eight of these nine patients the hemorrhage could clearly be detected, the remaining one had minor iSAH. Spearman analysis showed no significant correlation between time span and visibility (P = 0.660). In the remaining 57 patients (no iSAH) the hemorrhage was always visible achieving at least 3/5 points on the 5-point scale, and Spearman's analysis revealed only a weak correlation between time span and visibility (r = 0.493, P < 0.001).

CONCLUSION

The detectability of blood and its degradation products using SWI is reliably possible over a long period after intracranial hemorrhage.

Neuroradiologic Diagnosis of Minor Leak prior to Major SAH: Diagnosis by T1-FLAIR Mismatch

BACKGROUND AND PURPOSE

In major SAH, the only method to diagnose a preceding minor leak is to ascertain the presence of a warning headache by interview; however, poor clinical condition and recall bias can cause inaccuracy. We devised a neuroradiologic method to diagnose previous minor leak in patients with SAH and attempted to determine whether warning (sentinel) headaches were associated with minor leaks before major SAH.

MATERIALS AND METHODS

We retrospectively evaluated 127 patients who were admitted with SAH within 48 hours of ictus. Previous minor leak before major SAH was defined as T1WI-detected clearly bright hyperintense subarachnoid blood accompanied by SAH blood on FLAIR images that was distributed over a larger area than bright hyperintense subarachnoid blood on T1WI (T1-FLAIR mismatch).

RESULTS

The incidence of warning headache before SAH was 11.0% (14 of 127 patients, determined by interview). The incidence of T1-FLAIR mismatch (neuroradiologic diagnosis of minor leak before major SAH) was 33.9% (43 of 127 patients). Of the 14 patients with warning headache, 13 had a minor leak diagnosed by T1-FLAIR mismatch at the time of admission. Variables identified by multivariate analysis as significantly associated with minor leak diagnosed by T1-FLAIR mismatch included 80 years of age or older, rebleeding after admission, intracerebral hemorrhage on CT, and mRS scores of 3-6.

CONCLUSIONS

We conclude that warning headaches diagnosed by interview are not a product of recall bias but are the result of actual leaks from aneurysms.

[Diagnostic imaging of subarachnoid hemorrhage]

Subarachnoid hemorrhage is characterized by the extravasation of blood into the spaces covering the central nervous system which are filled with cerebrospinal fluid. The leading cause of non-traumatic subarachnoid hemorrhage is rupture of an intracranial aneurysm. Computed tomography (CT) scanning of the head should be the first examination performed in any patient with suspected subarachnoid hemorrhage. The characteristic appearance of extravasated blood is hyperdense. Head CT scanning can also demonstrate intraparenchymal hematomas, hydrocephalus and cerebral edema and can help predict the site of aneurysm rupture.

Spectrophotometry for cerebrospinal fluid pigment analysis

The use of spectrophotometry for the analysis of the cerebrospinal fluid (CSF) is reviewed. The clinically relevant CSF pigments--oxyhemoglobin and bilirubin--are introduced and discussed with regard to clinical differential diagnosis and potentially confounding variables (the four T's: traumatic tap, timing, total protein, and total bilirubin). The practical laboratory aspects of spectrophotometry and automated techniques are presented in the context of analytical and clinical specificity and sensitivity. The perceptual limitations of human color vision are highlighted and the use of visual assessment of the CSF is discouraged in light of recent evidence from a national audit in the United Kingdom. Finally, future perspectives including the need for longitudinal CSF profiling and routine spectrophotometric calibration are outlined.

Detection of subarachnoid hemorrhage at acute and subacute/chronic stages: comparison of four magnetic resonance imaging pulse sequences and computed tomography

BACKGROUND

Acute subarachnoid hemorrhage (SAH) has traditionally been diagnosed by computed tomography (CT); however, fluid-attenuated inversion recovery (FLAIR) is a magnetic resonance imaging (MRI) modality currently used to detect acute SAH. CT is insensitive in the detection of subacute or chronic SAH. The purpose of this study was to compare 4 MRI pulse sequences and CT in the detection of SAH in acute and subacute-to-chronic stages.

METHODS

From 2001-2003, we collected data for 22 patients (12 men and 10 women, aged 35-80 years) with SAH due to ruptured aneurysm (n = 11), trauma (3), or unknown origin (8). All patients underwent MRI and CT examination, with an interval of less than 12 hours between the 2 procedures. We divided patients into 2 groups according to the time from symptom onset to MRI evaluation: patients with MRI performed < or = 5 days post-ictus had acute-stage illness, whereas patients with MRI performed from day 6-30 post-ictus had a subacute-to-chronic condition. MRI (1.5-T) pulse sequences comprised spin-echo T1-weighted, fast spin-echo T2-weighted, FLAIR, and gradient-echo (GE) T2*-weighted images.

RESULTS

In the acute-stage group, SAH was seen as an area of high signal intensity compared with surrounding cerebrospinal fluid in 36.4% of cases on T1-weighted images, and in 100% on FLAIR images; low signal intensities were seen in 18.2% of cases on T2-weighted images, and in 90.9% on GE T2*-weighted images. High-attenuated SAH was seen on CT in 90.9% of cases. FLAIR (p = 0.008), GE T2*-weighted images (p = 0.012) and CT images (p = 0.012) were all statistically significant indicators of acute SAH. In the subacute/chronic-stage group, SAH was detected on T1-weighted images (36.4% of cases), FLAIR (33.3%), T2-weighted images (9.1%), GE T2*-weighted images (100%), and CT (45.5%). GE T2*-weighted images were significantly superior (p = 0.001) to other MRI pulse sequences and CT as indicators of subacute-to-chronic SAH.

CONCLUSION

FLAIR and GE T2* MRI pulse sequences, and CT scans, are all statistically significant indicators of acute SAH. GE T2*-weighted images are statistically significant indicators of subacute-to-chronic SAH, whereas other MRI pulse sequences, and CT scans, are not.

Current diagnostic approaches to subarachnoid haemorrhage

Over the past decade, significant advances have been made in the field of subarachnoid haemorrhage (SAH). Prompt diagnosis with high-resolution CT and intensive critical care support remain key aspects of good patient management. Early identification and definitive treatment of underlying ruptured aneurysms is generally advocated to reduce the risk of re-bleeding, a complication with high mortality and morbidity. Although intra-arterial digital subtraction angiography (DSA) is still considered the gold standard for sourcing aneurysms, CT angiography, especially with the evolution of multi-slice technology, is slowly gaining acceptance as a rapid, accessible and minimally invasive method which appears likely to replace DSA as first-line modality in the future. Furthermore, the advent of Guglielmi detachable coils and the ISAT trial have revolutionised the treatment of ruptured aneurysms, with a significant trend towards endovascular coiling away from operative clipping. Improvements in clinical experience, coiling technology and assistive devices now allow interventionalists to potentially treat the majority of aneurysms, including wide-necked or complex lesions. The uncertain long-term results of coiling, however, still fuel strong debate and controversy. This review summarises current diagnostic approaches to SAH from a radiological perspective, with an emphasis on aneurysmal SAH and an evidence-based approach to the role of imaging and interventional radiology in diagnosis, treatment and follow-up.

Evidence-based neuroimaging in acute ischemic stroke

The imaging work-up of patients with acute neurologic deficits should begin with noncontrast CT to exclude intracerebral hemorrhage. Based on positive results from the NINDS t-PA trial, the overriding objectives of imaging in the selection of patients for t-PA treatment are the detection of hemorrhage and rapid evaluation (speed of imaging). Despite its limited sensitivity for the identification of an ischemic stroke lesion, CT has multiple advantages over MR imaging in the initial diagnostic work-up. Advanced MR techniques promise to provide anatomic, physiologic, and vascular information in a single examination, and the ability to increase treatment specificity and improve outcome. Clinical outcome data are lacking; therefore, the routine use of screening MR imaging before t-PA therapy is not supported. Rigorous validation and correlation to clinical outcomes will be required.

Neuroimaging of stroke: a review

Advances in neuroimaging technology during the past 30 years have resulted in a virtual explosion in the amount of pathologic information that can be obtained in the clinical stroke setting. This neuroimaging revolution has led to a much better understanding of cerebrovascular and tissue pathology, creating a wide array of opportunities for acute treatment and secondary prevention. Advances include early and accurate detection of ischemic and infarcted tissue and the ability to reveal hypoperfused tissue at risk. Clinicians are increasingly able to noninvasively detect embolic and atherothrombotic intravascular lesions. Vascular lesions associated with stroke can be characterized through endovascular neuroimaging techniques and repaired by various means. In this article, we provide an overview and update on the various techniques used in the neuroimaging of stroke and intracranial hemorrhage, including computed tomography, magnetic resonance imaging, ultrasound, and catheter angiography. We outline the specific role of each modality in clinical practice.

Imaging of haemorrhagic stroke

Computed tomography (CT) is the reference standard for the imaging of acute non-traumatic intracranial haemorrhage. The sensitivity with which CT detects haemorrhage falls with time and lumber puncture remains mandatory for the exclusion of subarachnoid haemorrhage (SAH). Magnetic resonance (MR) imaging is, however, superior to CT in the subacute and chronic stages after haemorrhage. MR in addition offers pathophysiological information that can help with assessment of both the aetiology of and complications arising from both SAH and intra-parenchymal haemorrhage.

Causes and management of thunderclap headache: a comprehensive review

BACKGROUND

Thunderclap headache (or sudden severe headache) is an uncommon type of headache. Recognition and accurate diagnosis of this headache are important, because there is often a serious underlying brain disorder.

SUMMARY

In this article, causes and management of thunderclap headache are discussed. In the primary care setting, there is a serious cause in one third of patients, but in the hospital setting, up to two thirds of patients have a serious underlying brain disorder. Clues in history and physical examination can point to a possible serious underlying cause of thunderclap headache, such as subarachnoid hemorrhage, intracranial hematoma, or cerebral venous thrombosis. The remaining patients with thunderclap headache, however, have a primary headache disorder, such as migraine or (less frequently) tension headache with an unusual sudden onset, exertional headache, coital headache, cough headache, or cluster headache. The concept of thunderclap headache as a distinct clinical entity is discussed, with implications for its evaluation. Present radiological techniques are reviewed with regard to their diagnostic utility in detecting a serious brain disorder.

CONCLUSIONS

Thunderclap headache is an uncommon type of headache, and a serious underlying cause should be excluded.

Detection of subarachnoid haemorrhage with magnetic resonance imaging

OBJECTIVES

To measure the sensitivity and specificity of five MRI sequences to subarachnoid haemorrhage.

METHODS

Forty one patients presenting with histories suspicious of subarachnoid haemorrhage (SAH) were investigated with MRI using T1 weighted, T2 weighted, single shot fast spin echo (express), fluid attenuation inversion recovery (FLAIR), and gradient echo T2* sequences, and also by CT. Lumbar puncture was performed in cases where CT was negative for SAH. Cases were divided into acute (scanned within 4 days of the haemorrhage) and subacute (scanned after 4 days) groups.

RESULTS

The gradient echo T2* was the most sensitive sequence, with sensitivities of 94% in the acute phase and 100% in the subacute phase. Next most sensitive was FLAIR with values of 81% and 87% for the acute and subacute phases respectively. Other sequences were considerably less sensitive.

CONCLUSIONS

MRI can be used to detect subacute and acute subarachnoid haemorrhage and has significant advantages over CT in the detection of subacute subarachnoid haemorrhage. The most sensitive sequence was the gradient echo T2*.

Subarachnoid haemorrhage: diagnosis, causes and management

The incidence of subarachnoid haemorrhage (SAH) is stable, at around six cases per 100 000 patient years. Any apparent decrease is attributable to a higher rate of CT scanning, by which other haemorrhagic conditions are excluded. Most patients are <60 years of age. Risk factors are the same as for stroke in general; genetic factors operate in only a minority. Case fatality is approximately 50% overall (including pre-hospital deaths) and one-third of survivors remain dependent. Sudden, explosive headache is a cardinal but non-specific feature in the diagnosis of SAH: in general practice, the cause is innocuous in nine out of 10 patients in whom this is the only symptom. CT scanning is mandatory in all, to be followed by (delayed) lumbar puncture if CT is negative. The cause of SAH is a ruptured aneurysm in 85% of cases, non-aneurysmal perimesencephalic haemorrhage (with excellent prognosis) in 10%, and a variety of rare conditions in 5%. Catheter angiography for detecting aneurysms is gradually being replaced by CT angiography. A poor clinical condition on admission may be caused by a remediable complication of the initial bleed or a recurrent haemorrhage in the form of intracranial haematoma, acute hydrocephalus or global brain ischaemia. Occlusion of the aneurysm effectively prevents rebleeding, but there is a dearth of controlled trials assessing the relative benefits of early operation (within 3 days) versus late operation (day 10-12), or that of endovascular treatment versus any operation. Antifibrinolytic drugs reduce the risk of rebleeding, but do not improve overall outcome. Measures of proven value in decreasing the risk of delayed cerebral ischaemia are a liberal supply of fluids, avoidance of antihypertensive drugs and administration of nimodipine. Once ischaemia has occurred, treatment regimens such as a combination of induced hypertension and hypervolaemia, or transluminal angioplasty, are plausible, but of unproven benefit.

Management of intracranial aneurysms

Intracranial aneurysms are lesions commonly encountered by neurosurgeons, usually as a result of subarachnoid hemorrhage. The preferred treatment of these aneurysms is either surgical clipping or endovascular coiling, both of which eliminate the aneurysm from the normal circulation to prevent aneurysmal enlargement or additional hemorrhage. Despite advances over the last several decades in the understanding of intracranial aneurysms, morbidity from treatment of these lesions remains significant. This review will discuss the epidemiology, anatomy and pathophysiology, clinical and radiographic diagnosis, various treatment options, and potential complications from aneurysm treatment.