Detection of subarachnoid haemorrhage with magnetic resonance imaging

Multimodal imaging of the role of hyperglycemia following experimental subarachnoid hemorrhage

Hyperglycemia has been linked to worsening outcomes after subarachnoid hemorrhage (SAH). Nevertheless, the mechanisms involved in the pathogenesis of SAH have been scarcely evaluated so far. The role of hyperglycemia was assessed in an experimental model of SAH by T2 weighted, dynamic contrast-enhanced magnetic resonance imaging (T2W and DCE-MRI), [18F]BR-351 PET imaging and immunohistochemistry. Measures included the volume of bleeding, the extent of cerebral infarction and brain edema, blood brain barrier disruption (BBBd), neutrophil infiltration and matrix metalloprotease (MMP) activation. The neurofunctional outcome, neurodegeneration and myelinization were also investigated. The induction of hyperglycemia increased mortality, the size of the ischemic lesion, brain edema, neurodegeneration and worsened neurological outcome during the first 3 days after SAH in rats. In addition, these results show for the first time the exacerbating effect of hyperglycemia on in vivo MMP activation, Intercellular Adhesion Molecule 1 (ICAM-1) expression and neutrophil infiltration together with increased BBBd, bleeding volume and fibrinogen accumulation at days 1 and 3 after SAH. Notably, these data provide valuable insight into the detrimental effect of hyperglycemia on early BBB damage mediated by neutrophil infiltration and MMP activation that could explain the worse prognosis in SAH.

Subarachnoid Hemorrhage From Ruptured Aneurysms at the Internal Carotid Artery-Posterior Communicating Artery Bifurcation Not Detectable on Preoperative Imaging Studies

Since subarachnoid hemorrhage (SAH) due to the re-rupture of cerebral aneurysms severely worsens the prognosis, an accurate initial diagnosis is essential. Computed tomography (CT) and magnetic resonance imaging (MRI) usually detect aneurysmal subarachnoid hemorrhage (aSAH). However, in rare cases, its identification on CT- and MRI scans is difficult, and a cerebrospinal fluid (CSF) examination is required. We present preoperative imaging and intraoperative findings in patients whose aSAH detection necessitated a CSF examination. Of 225 aSAH patients who underwent preoperative imaging studies at our institution between April 2010 and August 2019, 3 females (1.3%, mean age 57.3 years) harbored undetectable aSAH due to the rupture of an internal carotid artery-posterior communicating artery (ICA-PcomA) aneurysm. The aneurysmal orientation was inferolateral. Intraoperatively, the anterior petroclinoid ligament hampered the detection of the aneurysms that firmly adhered to the surrounding arachnoid membrane. Sustained arterial pulsation and successive minor hemorrhage can lead to the gradual adhesion of an ICA-PcomA aneurysm to the surrounding arachnoid membrane and explain their atypical rupture undetectable on imaging studies and the development of acute subdural hematoma without SAH.

Convexity subarachnoid haemorrhage: a practical guide

Atraumatic convexity subarachnoid haemorrhage describes spontaneous bleeding into the convexities of the brain sulci without parenchymal involvement. Its many causes include reversible cerebral vasoconstriction syndrome, cerebral sinus venous thrombosis, posterior reversible encephalopathy syndrome and (in older people) cerebral amyloid angiopathy. We describe the clinical and radiological features of non-traumatic convexity subarachnoid haemorrhage with its various presentations, causes, treatments and prognoses, and use clinical vignettes to highlight important clinical points and pitfalls.

The Diagnostic Dilemma in Delayed Subarachnoid Hemorrhage: A Case Report

INTRODUCTION

Radiologically negative subarachnoid hemorrhage (SAH) has a low incidence and is associated with good clinical outcomes.

CASE REPORT

We present the case of a 44-year-old male with new-onset headaches, which began one week prior while bike riding. At an outside hospital, he had normal computed tomography head and angiogram. He declined a lumbar puncture. Over the following week, the headache was persistent. He lacked meningeal signs. Repeat studies were normal. Lumbar puncture was positive for xanthochromia.

CONCLUSION

Radiologically negative SAH should be included in the differential diagnosis of patients presenting with unremitting headache in the setting of recent exercise, despite negative imaging, and meningeal signs.

A case report: Ruptured aneurysm with a wide neck treated by flow diverter stent and coil embolization

Diagnosis and endovascular treatment for ruptured wide neck aneurysms are challenges in clinics, particularly in developing countries. In the present study, we described a clinical case with a ruptured wide neck aneurysm in Vietnam treated by flow diverter stent and coil embolization. A 77-year-old- female patient had a right droopy eyelid for 2 months. The patient was admitted to hospital on the second day after being presented with a sudden-severe headache. Cerebral computed tomography (CT) and magnetic resonance imaging (MRI) were taken on the second day and fifth day after the onset of the headache. The results showed an aneurysm in the right internal carotid artery but no potential subarachnoid hemorrhage (SAH) was displayed. An uncoagulated blood was found in cerebrospinal fluid indicated by a lumbar puncture test. Digital subtraction angiography provided images with one wide-neck right internal carotid aneurysm. The patient was treated by flow diverter stent and coil embolization and the dual antiplatelet therapy with ticagrelor and aspirin at home. After 45 days, the patient did not face with any complication, no neurological symptoms, and the aneurysm was partially thrombosed indicated by MRI images. These results suggested that a lumbar puncture should be analyzed on the patient with brain aneurysm appeared a sudden severe headache and even no potential SAH on brain MRI or CT was found. The combination of flow diverter stent and coil embolization to treat cases with ruptured wide necked aneurysms should be considered in the future.

Predictors and Impact of Sulcal SAH after Mechanical Thrombectomy in Patients with Isolated M2 Occlusion

BACKGROUND AND PURPOSE

Data on SAH after M2 mechanical thrombectomy are limited. We aimed to determine the prevalence of sulcal SAH after mechanical thrombectomy for M2 occlusion, its associated predictors, and the resulting clinical outcome.

MATERIALS AND METHODS

The study retrospectively reviewed the data of patients with acute ischemic stroke who underwent mechanical thrombectomy for isolated M2 occlusion. The patients were divided into 2 groups according to the presence of sulcal SAH after M2 mechanical thrombectomy. Angiographic and clinical outcomes were compared. Multivariable analysis was performed to identify independent predictors of sulcal SAH and unfavorable outcome (90-day mRS, 3-6).

RESULTS

Of the 209 enrolled patients, sulcal SAH was observed in 33 (15.8%) patients. The sulcal SAH group showed a higher rate of distal M2 occlusion (69.7% versus 22.7%), a higher of rate of superior division occlusion (63.6% versus 43.8%), and a higher M2 angulation (median, 128° versus 106°) than the non-sulcal SAH group. Of the 33 sulcal SAH cases, 23 (66.7%) were covert without visible intraprocedural contrast extravasation. Distal M2 occlusion (OR, 12.04; 95% CI, 4.56-35.67; P < .001), superior division (OR, 3.83; 95% CI, 1.43-11.26; P = .010), M2 angulation (OR, 1.02; 95% CI, 1.01-1.04; P < .001), and the number of passes (OR, 1.58; 95% CI, 1.22-2.09; P < .001) were independent predictors of sulcal SAH. However, covert sulcal SAH was not associated with an unfavorable outcome (P = .830).

CONCLUSIONS

After mechanical thrombectomy for M2 occlusion, sulcal SAH was not uncommon and occurred more frequently with distal M2 occlusion, superior division, acute M2 angulation, and multiple thrombectomy passes (≥3). The impact of covert sulcal SAH was mostly benign and was not associated with an unfavorable outcome.

Central Nervous System Systemic Lupus Erythematosus: Pathophysiologic, Clinical, and Imaging Features

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by multiple immunologic abnormalities and has the potential to involve the central nervous system (CNS). The prevalence of SLE seems to be growing, possibly because of earlier diagnosis and improved survival; however, the associated mortality is still high. The mortality is associated with disease-related risk factors such as lupus disease activity, young age, and organ damage or with antiphospholipid syndrome (APS). Neuropsychiatric SLE (NPSLE), which is caused by SLE-related CNS involvement, comprises a broad range of neurologic and psychiatric manifestations with varying severity, which can make this disease indistinguishable from other conditions that are unrelated to SLE. No unifying pathophysiology has been found in the etiology of NPSLE, suggesting that this condition has multiple contributors such as various immune effectors and the brain-intrinsic neuroimmune interfaces that are breached by the immune effectors. The postulated neuroimmune interfaces include the blood-brain barrier, blood-cerebrospinal fluid barrier, meningeal barrier, and glymphatic system. On the basis of the immunologic, pathologic, and imaging features of NPSLE, the underlying pathophysiology can be classified as vasculitis and vasculopathy, APS, demyelinating syndrome, or autoimmune antibody-mediated encephalitis. Each pathophysiology has different imaging characteristics, although the imaging and pathophysiologic features may overlap. Moreover, there are complications due to the immunocompromised status caused by SLE per se or by SLE treatment. Radiologists and clinicians should become familiar with the underlying mechanisms, radiologic findings, and complications of NPSLE, as this information may aid in the diagnosis and treatment of NPSLE. Online supplemental material is available for this article. ^©RSNA, 2022.

Diagnosis and Treatment of Unruptured Intracranial Aneurysms and Aneurysmal Subarachnoid Hemorrhage

Unruptured intracranial aneurysms (UIAs) are commonly acquired vascular lesions that form an outpouching of the arterial wall due to wall thinning. The prevalence of UIAs in the general population is 3.2%. In contrast, an intracranial aneurysm may be manifested after rupture with classic presentation of a thunderclap headache suggesting aneurysmal subarachnoid hemorrhage (SAH). Previous consensus suggests that although small intracranial aneurysms (<7 mm) are less susceptible to rupture, aneurysms larger than 7 mm should be treated on a case-by-case basis with consideration of additional risk factors of aneurysmal growth and rupture. However, this distinction is outdated. The PHASES score, which comprises data pooled from several prospective studies, provides precise estimates by considering not only the aneurysm size but also other variables, such as the aneurysm location. The International Study of Unruptured Intracranial Aneurysms is the largest observational study on the natural history of UIAs, providing the foundation to the current guidelines for the management of UIAs. Although SAH accounts for only 3% of all stroke subtypes, it is associated with considerable burden of morbidity and mortality. The initial management is focused on stabilizing the patient in the intensive care unit with close hemodynamic and serial neurologic monitoring with endovascular or open surgical aneurysm treatment to prevent rebleeding. Since the results of the International Subarachnoid Aneurysm Trial, treatment of aneurysmal SAH has shifted from surgical clipping to endovascular coiling, which demonstrated higher odds of survival free of disability at 1 year after SAH. Nonetheless, aneurysmal SAH remains a public health hazard and is associated with high rates of disability and death.

The role of imaging in the management of non-traumatic subarachnoid hemorrhage: a practical review

The purpose of this review is to understand the role of imaging in the diagnosis and management of non-traumatic subarachnoid hemorrhage (SAH). SAH is a life-threatening emergency and a relatively common entity, the most common etiology being ruptured aneurysms. Multiple conundrums exist in literature at various steps of its imaging workup: diagnosis, management, and follow-up. We target our review to highlight the most effective practice and suggest efficient workup plans based on literature search, and describe in detail the clinical diagnostic and prognostic scales, role of CT scan, lumbar puncture, and MR, including angiography in the diagnosis and workup of SAH and its complications, and try to simplify the conundrums. Practical knowledge of imaging workup of SAH can help guide correct management of these patients, so as to reduce morbidity and mortality without resource overutilization.

Neuroimaging in Sickle Cell Disease: A Review

Sickle cell disease is the most common hereditary hemoglobinopathy, which results in abnormally shaped and rigid red blood cells. These sickle-shaped red blood cells cause vaso-occlusion and ischemic phenomena that can affect any organ in the body. As a common cause of disability, the neurological manifestations of sickle cell disease are particularly important. Neuroimaging has a crucial role in the diagnosis, management, and prevention of the complications of sickle cell disease. These complications can affect the brain parenchyma, vasculature, and skull and can be ascribed directly or indirectly to a vasculopathy of small and large vessels. Vaso-occlusion can cause ischemic stroke. Ischemic damage in the absence of an acute neurological deficit, and therefore only apparent on neuroimaging, is termed silent cerebral ischemia. Weakening of the arterial walls can cause aneurysms. In its most severe form, a vasculopathy of the terminal internal carotid arteries can progress to moyamoya syndrome, characterized by steno-occlusive disease and the formation of friable collateral arteries. Rupture of aneurysms or friable collateral arteries is a potential cause of intracranial hemorrhage. The skull and vertebrae may be affected by extra-medullary hematopoiesis, due to severe anemia, or iron deposition, due to chronic red blood cell transfusion. Impaired blood supply to bone is associated with osteomyelitis and osteonecrosis. Fat embolization syndrome is a rare complication of osteonecrosis, which may cause devastating neurological impairment. Awareness and early recognition of the diverse manifestations of sickle cell disease on neuroimaging is crucial to ensure optimal treatment in a complex patient cohort.

Subarachnoid extension of lobar hemorrhage on acute/subacute MRI is associated with cerebral amyloid angiopathy criteria

Subarachnoid hemorrhage extension (SAHE) in the acute phase of cerebral amyloid angiopathy (CAA)-related lobar hemorrhage (LH) assessed by CT is very frequent. Recently, SAHE, together with finger-like projections on CT and ApoE4, has been used in a prediction model for histopathologically proven CAA showing excellent discrimination. Our aim was to analyze SAHE on MRI in the acute and subacute phase of LH in patients with and without associated hemorrhagic features supportive of CAA (i.e. chronic LH, cortical superficial siderosis [CSS], and strictly lobar cerebral microbleeds [CMB]). We retrospectively studied SAHE on MRI performed in the acute and subacute phase (within 21 days) in a cohort of consecutive patients with acute LH recruited between January 2012 and April 2018. Sixty-eight acute LH patients (35 men and 33 women, mean age 74 [range 50-89]) were analyzed. Mean delay between symptom onset and MRI was 3.8 days, and 32 patients underwent MRI within 24 h. Based on MRI, 51 patients were classified as probable CAA and 17 patients without probable CAA. Both groups were comparable regarding age, sex, time of MRI performance, MRI field strength, and acute LH volume. Overall, SAHE was observed in 46 (68%) patients, including 39 (76%) patients with probable CAA and 7 (41%) patients without probable CAA (p = 0.015). SAHE presence was also associated with larger LH volumes. During the work-up in the acute/subacute phase of patients with acute LH, in addition to T2*-weighted imaging in search for other hemorrhagic features (chronic LH, CSS, or lobar CMB) evoking probable underlying CAA etiology, search for SAHE on adapted MRI sequences (FLAIR and T2*-weighted imaging) seems to be interesting because of the association with the presence of probable CAA criteria.

Traumatic Brain Injury: Imaging Patterns and Complications

While the diagnosis of traumatic brain injury (TBI) is a clinical decision, neuroimaging remains vital for guiding management on the basis of identification of intracranial pathologic conditions. CT is the mainstay of imaging of acute TBI for both initial triage and follow-up, as it is fast and accurate in detecting both primary and secondary injuries that require neurosurgical intervention. MRI is more sensitive for the detection of certain intracranial injuries (eg, axonal injuries) and blood products 24-48 hours after injury, but it has limitations (eg, speed, accessibility, sensitivity to motion, and cost). The evidence primarily supports the use of MRI when CT findings are normal and there are persistent unexplained neurologic findings or at subacute and chronic periods. Radiologists should understand the role and optimal imaging modality to use, in addition to patterns of primary brain injury and their influence on the risk of developing secondary brain injuries related to herniation. ^©RSNA, 2019 See discussion on this article by Mathur and Nicolaou.

Intracranial High-Grade Stenosis and Hyperhomocysteinemia Presenting as Cortical Subarachnoid Hemorrhage Concomitant with Acute Ischemic Stroke in a Young Man

BACKGROUND Cortical subarachnoid hemorrhage (cSAH) is a rare clinical presentation with different causes, but rarely happens along with acute ischemic stroke. Intracranial high-grade stenosis originated from brain has been regarded as an unusual cause of cSAH, especially in young adults. CASE REPORT A case of 33-year-old male presented with mild headache and spontaneous left-sided body weakness. Initial brain computed tomography (CT) showed cSAH in the right superior frontal sulcus. Further neuroimaging examinations including magnetic resonance imaging (MRI), digital subtraction angiography (DSA), transesophageal echocardiogram (TEE); in addition, lumbar puncture and blood tests were performed. Diffusion-weighted imaging (DWI) showed an acute infarction in the right frontal lobe and corona radiata of the territory of middle cerebral artery (MCA). The MR angiography (MRA) displayed no flow signal in the right middle cerebral artery M1-segment, while the DSA displayed bloodstream slowness in the right MCA M1-segment which suggested high-grade stenosis of the right MCA. The abnormal laboratory data suggested hyperhomocysteinemia, and excluded causes of thrombosis, infection, or cancer. The mechanism of cSAH may come about in severe atherosclerotic stenosis of MCAs by the broken of expanded tenuous compensatory pial vessels. The patient had good recovered at follow-up. CONCLUSIONS This case demonstrates cSAH with acute ischemic stroke, which is an uncommon complication, in a young adult stroke patient; a high-grade atherosclerotic stenosis of the MCA was identified as the etiology.

Evaluation of subacute subarachnoid haemorrhage detection using a magnetic resonance imaging sequence: Double inversion recovery

BACKGROUND AND OBJECTIVES

The diagnosis of subarachnoid hemorrhage (SAH) especially at the subacute stage is still a challenging issue using the conventional imaging modalities. Here we evaluated the role of double inversion recovery (DIR) sequence of MRI compared with the conventional gradient-recalled echo (GRE)-T2*-W and susceptibility-weighted imaging (SWI) sequences in the diagnosis of subacute SAH.

MATERIALS AND METHODS

This prospective study was conducted on 21 patients with SAH, which were diagnosed using CT scan at the initial step. In the third week after the injury (14-20 days), all patients underwent a brain MRI exam that included T2*-W, SWI, and DIR imaging sequences. All images were independently read by two radiologists, who were blinded to the clinical history of the patients. The presence or absence of SAH was reviewed and assessed in 6 anatomical regions.

RESULTS

On the DIR images, 20 patients were found to have at least one subarachnoid signal abnormality, while the SWI and T2*-W images identified SAH areas on 17 and 15 patients, respectively. The highest rate of inter-observer consensus by the DIR sequence was found in the interhemispheric fissure and perimesencephalic area (k = 1). Also, a highest rate of inter-observer consensus using SWI was found in the interhemispheric fissure and posterior fossa cistern area (k = 1). A weak agreement was found in frontal-parietal convexity using SWI (k = 0.447), and in posterior fossa cistern by the T2* sequence (k = 0.447).

CONCLUSION

In conclusion, the DIR sequence was more reliable at identifying signal abnormalities in subacute SAH patients than the T2*-W and SWI sequence, and is suggested as a promising imaging technique for detecting hemorrhagic areas without considering the anatomical distribution of SAH.

Magnetic Resonance Imaging in Aneurysmal Subarachnoid Hemorrhage: Current Evidence and Future Directions

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with an unacceptably high mortality and chronic disability in survivors, underscoring a need to validate new approaches for treatment and prognosis. The use of advanced imaging, magnetic resonance imaging (MRI) in particular, could help address this gap given its versatile capacity to quantitatively evaluate and map changes in brain anatomy, physiology and functional activation. Yet there is uncertainty about the real value of brain MRI in the clinical setting of aSAH.

METHODS

In this review, we discuss current and emerging MRI research in aSAH. PubMed was searched from inception to June 2017, and additional studies were then chosen on the basis of relevance to the topics covered in this review.

RESULTS

Available studies suggest that brain MRI is a feasible, safe, and valuable testing modality. MRI detects brain abnormalities associated with neurologic examination, outcomes, and aneurysm treatment and thus has the potential to increase knowledge of aSAH pathophysiology as well as to guide management and outcome prediction. Newer pulse sequences have the potential to reveal structural and physiological changes that could also improve management of aSAH.

CONCLUSION

Research is needed to confirm the value of MRI-based biomarkers in clinical practice and as endpoints in clinical trials, with the goal of improving outcome for patients with aSAH.

Vessel wall enhancement of intracranial aneurysms: fact or artifact?

OBJECTIVE

For patients with subarachnoid hemorrhage (SAH) and multiple intracranial aneurysms, it is often challenging to identify the ruptured aneurysm. Some investigators have asserted that vessel wall imaging (VWI) can be used to identify the ruptured aneurysm since wall enhancement after contrast agent injection is presumably related to inflammation in unstable and ruptured aneurysms. The aim of this study was to determine whether additional factors contribute to aneurysm wall enhancement by assessing imaging data in a series of patients.

METHODS

Patients with symptoms of SAH who subsequently underwent VWI in the period between January 2017 and September 2018 were eligible for study inclusion. Three-dimensional turbo spin-echo sequences with motion-sensitized driven-equilibrium preparation pulses were acquired using a 3-T MRI scanner to visualize the aneurysm wall. Identification of the ruptured aneurysm was based on aneurysm characteristics and hemorrhage distributions on MRI. Complementary imaging data (CT, DSA, MRI) were used to assess potential underlying enhancement mechanisms. Additionally, aneurysm luminal diameter measurements on MRA were compared with those on contrast-enhanced VWI to assess the intraluminal contribution to aneurysm enhancement.

RESULTS

Six patients with 14 aneurysms were included in this series. The mean aneurysm size was 5.8 mm (range 1.1–16.9 mm). A total of 10 aneurysms showed enhancement on VWI; 5 ruptured aneurysms showed enhancement, and 1 unruptured but symptomatic aneurysm showed enhancement on VWI and ruptured 1 day later. Four unruptured aneurysms showed enhancement. In 6 (60%) of the 10 enhanced aneurysms, intraluminal diameters appeared notably smaller (≥ 0.8 mm smaller) on contrast-enhanced VWI compared to their appearance on multiple overlapping thin slab acquisition time of flight (MOTSA-TOF) MRA and/or precontrast VWI, suggesting that enhancement was at least partially in the aneurysm lumen itself.

CONCLUSIONS

Several factors other than the hypothesized inflammatory response contribute to aneurysm wall enhancement. In 60% of the cases in this study, enhancement was at least partially caused by slow intraaneurysmal flow, leading to pseudo-enhancement of the aneurysm wall. Notwithstanding, there seems to be clinical value in differentiating ruptured from unruptured aneurysms using VWI, but the hypothesis that we image the inflammatory cell infiltration in the aneurysm wall is not yet confirmed.

Misdiagnosis of acute subarachnoid hemorrhage in the era of multimodal diagnostic options

OBJECTIVE

Patients suffering from aneurysmatic Subarachnoid Hemorrhage (SAH) may present with a variety of symptoms. The aim of this study is to evaluate the spectrum of misdiagnoses and to analyze the significance of delay of correct diagnosis on the clinical outcome.

METHODS

The data was collected prospectively from 2003 to 2013. Patients diagnosed with disease different from aneurysmal SAH by the initially treating physician, and admitted to our department with a delay of at least 24 h after the beginning of the symptoms, were included in this study. We analyzed the various diagnoses that were ascertained instead of SAH and which medical specialty had provided them.

RESULTS

Overall 704 patients were treated with acute SAH. The inclusion criteria were matched in 76 patients (13.7%). Eleven specialties were involved in the initial patients' treatment. The time interval between initial symptoms and neurosurgical admission varied enormously. Statistically, higher Hunt & Hess score did not lead to an earlier diagnosis (p = 0.56) nor did localisation of the aneurysm (p = 0.75). Lower Fisher score was led to delayed diagnosis (p = 0.02). Delay of diagnosis was not significantly associated with the outcome (p = 0.08) whereas Hunt & Hess grade on admission was a strong predictor for bad outcome (p = 0.00001) as was cerebral vasospasm on the first angiogram (p < 0.05).

CONCLUSION

A straightforward diagnosis of SAH despite diffuse and unspecific symptoms is crucial for the successful treatment of these patients, especially with high grade SAH.

Reversible cerebral vasoconstriction syndrome: an important and common cause of thunderclap and recurrent headaches

Reversible cerebral vasoconstriction syndrome is an intracranial vascular manifestation of a wide variety of diseases. It is the second most common cause of thunderclap headache, the most common cause of recurrent severe secondary headaches, and, in patients <60 years of age, has been reported as the commonest cause of isolated convexity subarachnoid haemorrhage. Radiologically, its key feature is vasoconstriction of the intracranial vessels, a dynamic process that is typically maximal at 2 weeks, varies in its distribution over the course of the disease, and typically resolves after 3 months. It can have haemorrhagic and ischaemic complications and sometimes occurs in concert with posterior reversible encephalopathy syndrome. It also has important associations with dissection and migraine. Rarer atypical cases can present with mild headache, no headache at all, or even a comatose state. This paper provides a detailed review of this syndrome, its pathophysiology, differential diagnosis, imaging findings, and work-up. It also describes the role that high-resolution magnetic resonance imaging (MRI) techniques can have in diagnosing the disease and emphasises the central role that all radiologists have in detecting this important and underdiagnosed condition.

Primary Angiitis of the Central Nervous System

Background and Purpose—

Primary angiitis of the central nervous system remains challenging. To report an overview and pictorial review of brain magnetic resonance imaging findings in adult primary angiitis of the central nervous system and to determine the distribution of parenchymal, meningeal, and vascular lesions in a large multicentric cohort.

Methods—

Adult patients from the French COVAC cohort (Cohort of Patients With Primary Vasculitis of the Central Nervous System), with biopsy or angiographically proven primary angiitis of the central nervous system and brain magnetic resonance imaging available at the time of diagnosis were included. A systematic imaging review was performed blinded to clinical data.

Results—

Sixty patients met inclusion criteria. Mean age was 45 years (±12.9). Patients initially presented focal deficit(s) (83%), headaches (53%), cognitive disorder (40%), and seizures (38.3%). The most common magnetic resonance imaging finding observed in 42% of patients was multiterritorial, bilateral, distal acute stroke lesions after small to medium artery distribution, with a predominant carotid circulation distribution. Hemorrhagic infarctions and parenchymal hemorrhages were also frequently found in the cohort (55%). Acute convexity subarachnoid hemorrhage was found in 26% of patients and 42% demonstrated pre-eminent leptomeningeal enhancement, which is found to be significantly more prevalent in biopsy-proven patients (60% versus 28%; P =0.04). Seven patients had tumor-like presentations. Seventy-seven percent of magnetic resonance angiographic studies were abnormal, revealing proximal/distal stenoses in 57% and 61% of patients, respectively.

Conclusions—

Adult primary angiitis of the central nervous system is a heterogenous disease, with multiterritorial, distal, and bilateral acute stroke being the most common pattern of parenchymal lesions found on magnetic resonance imaging. Our findings suggest a higher than previously thought prevalence of hemorrhagic transformation and other hemorrhagic manifestations.

Thunderclap Headache

PURPOSE OF REVIEW

A thunderclap headache is a very severe headache that reaches its maximum intensity within 1 minute. Patients with thunderclap headache must be evaluated emergently and comprehensively to rule out underlying disorders that can be associated with high mortality and morbidity, determine the cause for the thunderclap headache, and initiate targeted therapy. This review presents an up-to-date summary on the clinical presentation, diagnostic evaluation, and causes of thunderclap headache.

RECENT FINDINGS

Numerous etiologies for thunderclap headaches have been identified, with the most common causes being subarachnoid hemorrhage and reversible cerebral vasoconstriction syndrome. Other relatively common causes include cervical artery dissection, cerebral venous sinus thrombosis, and spontaneous intracranial hypotension. Although "primary" thunderclap headache is typically accepted to exist, it may be that such cases represent missed diagnoses of underlying causes. The urgent evaluation of the patient with thunderclap headache includes brain CT, followed by lumbar puncture if the brain CT is nondiagnostic. If a diagnosis is not reached following brain CT and lumbar puncture, brain MRI and imaging of the brain and cervical vasculature are indicated.

SUMMARY

Patients with thunderclap headache require an emergent and comprehensive evaluation to identify the underlying cause and to initiate appropriate therapy.

Imaging Evaluation of Acute Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of morbidity and mortality worldwide. Imaging plays an important role in the evaluation, diagnosis, and triage of patients with TBI. Recent studies suggest that it also helps predict patient outcomes. TBI consists of multiple pathoanatomic entities. This article reviews the current state of TBI imaging including its indications, benefits and limitations of the modalities, imaging protocols, and imaging findings for each of these pathoanatomic entities. Also briefly surveyed are advanced imaging techniques, which include several promising areas of TBI research.

Controversies in the Diagnosis of Subarachnoid Hemorrhage

BACKGROUND

Headache is a common chief complaint in emergency departments, accounting for 2% of visits, and subarachnoid hemorrhage (SAH) is a life-threating cause of headache. This deadly disease is most commonly due to aneurysmal rupture. Various approaches exist for diagnosis, with recent studies evaluating these approaches. A great deal of controversy exists about the optimal diagnosis strategy for SAH.

OBJECTIVE

This article in the Best Clinical Practice Series seeks to educate emergency physicians on the recent literature in the diagnosis of SAH and provide an evidence-based approach.

DISCUSSION

Various diagnostic strategies exist, including use of noncontrast head computed tomography (CT) alone, CT/lumbar puncture (LP) in combination, CT/CT angiography, and magnetic resonance imaging/magnetic resonance angiography. The use of clinical decision rules has also been espoused, and several contemporary studies have evaluated cerebrospinal fluid results of red blood cell count and xanthochromia in the diagnosis of SAH. Recent literature supports that a negative head CT done within 6 h of headache onset places the patient at a < 1% risk for SAH. With the complex literature, a shared decision-making model should be followed with options, risks, and benefits discussed with the patient.

CONCLUSIONS

Literature support exists for all of the diagnostic strategies. The American College of Emergency Physicians Clinical Policy supports CT and LP for definitive diagnosis. Risk stratification and a shared decision-making model with the patient should be followed, and a negative head CT within 6 h of headache onset places patient at a risk of < 1% for having SAH.

Detection of aneurysmal subarachnoid hemorrhage 3 months after initial bleeding: evaluation of T2* and FLAIR MR sequences at 3 T in comparison with initial non-enhanced CT as a gold standard

OBJECTIVE

To investigate the ability of T2* and fluid-attenuated inversion recovery (FLAIR) MR sequences to detect hemosiderin deposition 3 months after aneurysmal subarachnoid hemorrhage (SAH) in comparison with early non-enhanced CT (NECT) as a gold standard.

MATERIALS AND METHODS

From September 2008 through May 2013, patients with aneurysmal SAH were included if a NECT less than 24 h after the onset of symptoms showed a SAH, and MRI, including T2* and FLAIR sequences, was performed 3 months later. All aneurysms were treated endovascularly. NECT and MR sequences were blindly analyzed for the presence of SAH (NECT) or hemosiderin deposition (MRI). When positive, details of the spatial distribution of SAH or hemosiderin deposits were noted. Sensitivities were calculated for each patient. Sensitivities, specificities, and positive predictive values (PPVs) were calculated for each location.

RESULTS

Forty-nine patients (mean age 52.9 years) were included. Bleeding-related patterns were identified in 43 patients (87.8%) on T2* and 10 patients (20.4%) on FLAIR. T2* was highly predictive of the location of the initial hemorrhage, especially in the Sylvian cisterns (PPVs 95% and 100%) and the anterior interhemispheric fissure (PPV 90%).

CONCLUSIONS

The T2* sequence can detect and localize a previous SAH a few months after aneurysmal bleeding.

Neuroimaging in Secondary Headache Disorders

A secondary headache may develop de novo or in patients with a history of primary headaches, and a thorough history and neurological exam often helps to suspect a secondary etiology. The causes of secondary headaches include tumors, vascular etiologies, structural brain disorders, infection, inflammation, and alterations of cerebrospinal fluid pressure dynamics. Computed tomography (CT) is very sensitive for detecting acute hemorrhage but magnetic resonance imaging (MRI) is preferred over a head CT in subacute and non-emergent cases. Obtaining the correct diagnosis may include incorporation of intravenous contrast agents, special imaging sequences, and functional imaging techniques.

Diffusion-weighted signal patterns of intracranial haemorrhage

The signal pattern of intracranial haemorrhage on diffusion-weighted imaging (DWI) as it evolves over time is rarely discussed due to the sensitivity of T2*-weighted sequences and the specificity of classic signal patterns on T1 and T2-weighted sequences. The DWI signal is strongly affected by the magnetic susceptibility of paramagnetic blood products and, therefore, is markedly hypointense in the same phases that demonstrate hypointensity on T2*-weighted sequences; however, hyperacute haemorrhage (oxyhaemoglobin-predominant clot) and late subacute haemorrhage (extracellular methaemoglobin) do not demonstrate T2* hypointensity. Moreover, T2*-weighted sequences are less sensitive to the presence of extra-axial haemorrhage than to intraparenchymal haemorrhage. At these stages of evolution, haemorrhage demonstrates high DWI signal in association with low ADC values, which may be more pronounced than even its corresponding fluid-attenuated inversion recovery (FLAIR) signal. DWI is useful for identifying hyperacute subarachnoid haemorrhage and as a problem-solving tool in challenging cases.

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.

Recognizing the signs and symptoms of aneurysmal subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating neurologic condition with a high mortality and long term neurological morbidity in 50% of survivors. In addition, SAH commonly affects young patients causing substantial loss of productive life years and resulting in significant long term healthcare costs. Early recognition of the signs and symptoms of SAH is absolutely critical to earlier intervention, and delays in diagnosis can have devastating consequences. To avoid such delays in SAH diagnosis, the medical provider should recognize its signs and symptoms. Neuroimgaging, cerebrospinal fluid examination and angiography (invasive or non-invasive) facilitate early diagnosis of SAH. The purpose of this review is not to provide an exhaustive critique of the available literature, rather, it is to provide an overview that will better enable a provider to recognize and initiate the workup of patients with SAH.

Double inversion recovery MR sequence for the detection of subacute subarachnoid hemorrhage

BACKGROUND AND PURPOSE

The diagnosis of subacute subarachnoid hemorrhage is important because rebleeding may occur with subsequent life-threatening hemorrhage. Our aim was to determine the sensitivity of the 3D double inversion recovery sequence compared with CT, 2D and 3D FLAIR, 2D T2*, and 3D SWI sequences for the detection of subacute SAH.

MATERIALS AND METHODS

This prospective study included 25 patients with a CT-proved acute SAH. Brain imaging was repeated between days 14 and 16 (mean, 14.75 days) after clinical onset and included MR imaging (2D and 3D FLAIR, 2D T2*, SWI, and 3D double inversion recovery) after CT (median delay, 3 hours; range, 2-5 hours). A control group of 20 healthy volunteers was used for comparison. MR images and CT scans were analyzed independently in a randomized order by 3 blinded readers. For each subject, the presence or absence of hemorrhage was assessed in 4 subarachnoid areas (basal cisterns, Sylvian fissures, interhemispheric fissure, and convexity) and in brain ventricles. The diagnosis of subacute SAH was defined by the presence of at least 1 subarachnoid area with hemorrhage.

RESULTS

For the diagnosis of subacute SAH, the double inversion recovery sequence had a higher sensitivity compared with CT (P < .001), 2D FLAIR (P = .005), T2* (P = .02), SWI, and 3D FLAIR (P = .03) sequences. Hemorrhage was present for all patients in the interhemispheric fissure on double inversion recovery images, while no signal abnormality was noted in healthy volunteers. Interobserver agreement was excellent with double inversion recovery.

CONCLUSIONS

Our study showed that the double inversion recovery sequence has a higher sensitivity for the detection of subacute SAH than CT, 2D or 3D FLAIR, 2D T2*, and SWI.

Treatment of subarachnoid hemorrhage

Nontraumatic subarachnoid hemorrhage from intracranial aneurysm rupture presents with sudden severe headache. Initial treatment focuses on airway management, blood pressure control, and extraventricular drain for hydrocephalus. After identifying the aneurysm, they may be clipped surgically or endovascularly coiled. Nimodipine is administered to maintain a euvolemic state and prevent delayed cerebral ischemia (DCI). Patients may receive anticonvulsants. Monitoring includes serial neurologic assessments, transcranial Doppler ultrasonography, computed tomography perfusion, and angiographic studies. Treatment includes augmentation of blood pressure and cardiac output, cerebral angioplasty, and intra-arterial infusions of vasodilators. Although early mortality is high, about one half of survivors recover with little disability.

Cerebral convexity subarachnoid hemorrhage: various causes and role of diagnostic imaging

Computed tomography (CT) and magnetic resonance imaging (MRI) have made it relatively easy to diagnose cortical convexity subarachnoid hemorrhages (cSAH); however, the evaluation of these hemorrhages should not be limited to size and location. It is imperative that possible underlying etiologies be identified so that clinicians may properly treat and prevent this potentially catastrophic event. The goal of this article is to review etiologies of cortical convexity subarachnoid hemorrhages, from common causes such as cerebral amyloid angiopathy to less common causes such as reversible cerebral vasoconstriction syndrome and moyamoya. The specific imaging findings of each etiology that may be responsible for these hemorrhages are described in this article so that the radiologist may properly aid in the diagnosis of the underlying cause.

Headaches caused by vascular disorders

The clinical association between stroke and headache is complex, ranging from the largely irrelevant to the highly specific. The incidence and clinical relevance of acute headache are highly dependent on stroke subtype and etiology. In this article the issue of headache accompanying acute stroke is addressed in some detail.