Posterior reversible encephalopathy syndrome (PRES) and CT perfusion changes

Cerebral hypometabolism in a pediatric patient with clinically resolved posterior reversible encephalopathy syndrome

A 4-year-old boy with Nuclear factor-kappa B Essential Modulator deficiency syndrome presented with encephalopathy post haematopoietic stem cell transplantation. MRI demonstrated T2/FLAIR-hyperintensities in the posterior cerebral cortex concerning for posterior reversible encephalopathy syndrome. Clinical improvement was appreciated following withdrawal of the suspected offending pharmacological agent (Cyclosporine). An 18F-FDG PET/CT performed 2 months later to screen for post-transplant lymphoproliferative disease demonstrated markedly reduced FDG uptake in the posterior cerebral cortex, involving the parietal and occipital lobes. We describe, to the best of our knowledge, the first case of profound cerebral hypometabolism in a child with clinically resolved posterior reversible encephalopathy syndrome.

[Posterior reversible encephalopathy syndrome in autoimmune disorders]

Posterior reversible encephalopathy syndrome (PRES) is characterized by nonspecific symptoms, including not only pronounced non-focal and various focal neurological signs but also specific neuroimaging features, including vasogenic edema affecting predominantly the posterior area. PRES usually develops in the setting of acute arterial hypertension. However, it is not uncommon for PRES to develop in non-hypertensive patients, including people with autoimmune disorders (multiple sclerosis, neuromyelitis optica spectrum disorder, etc). PRES could also be due to the toxic effects of drugs or other substances. The pathophysiological mechanisms of PRES include impaired autoregulation of cerebral blood flow due to acute arterial hypertension and toxic endotheliotropic effects of endogenous and exogenous factors.

Pediatric Posterior Reversible Encephalopathy Syndrome: A Review With Emphasis on Neuroimaging Characteristics

Posterior reversible encephalopathy syndrome (PRES) is a neurological disorder characterized by the sudden onset of seizures, headaches, and visual disturbances. Its exact cause is unknown, but several triggers and associated conditions are identified, including high blood pressure, kidney dysfunction, and various medications. Magnetic resonance imaging (MRI) plays a crucial role in diagnosis due to its high sensitivity and specificity for detecting characteristic features. Pediatric PRES exhibit age-dependent differences in triggers, radiological findings, and clinical course. The lesions typically involve the posterior cortical and subcortical white matter, but atypical locations and features are also observed. While generally reversible with appropriate treatment, PRES carries a risk of permanent neurological damage. Despite increasing cases, the current literature on pediatric PRES remains limited. This review highlights the need for further research to understand the mechanisms, delineate distinct clinical and radiological features, and develop precise diagnostic and management strategies for pediatric patients.

Perfusion Deficits in Patients with Posterior Reversible Encephalopathy Syndrome: a Retrospective, Two-Center Study

BACKGROUND

Posterior reversible encephalopathy syndrome (PRES) is manifested by acute neurological symptoms in patients with varied predisposing factors and characteristic findings on brain imaging. Cerebrovascular autoregulation is thought to be altered in PRES. However, it remains unclear whether cerebral hypoperfusion or hyperperfusion is the initiating event. We aimed to describe the brain perfusion status in untreated patients with PRES.

METHODS

Patients with PRES who underwent cerebral perfusion studies on presentation were retrospectively identified from (1) a prospective database of patients with PRES admitted to Saint Mary's Hospital, Mayo Clinic, Rochester from January 2005 to December 2021 and (2) University of Nebraska Medical Center electronic database from January 2010 to December 2021. Demographics, past medical history, presenting symptoms, cause of PRES, and clinical outcomes were recorded. Brain imaging studies were reviewed. We recorded the location of brain lesions, the time from symptoms onset to perfusion study, blood pressure at the time of the perfusion study, and blood pressure lowering treatments.

RESULTS

Five patients (four women, median age 66 years) were included. Causes of PRES were acute hypertension (n = 3), perioperative blood pressure fluctuations, and treatment with pazopanib. Four patients had chronic hypertension. Presenting symptoms were encephalopathy (n = 5), focal neurological symptoms (n = 4), and seizures (n = 2). All patients underwent computed tomography (CT) perfusion performed within 12 h of symptoms onset. All but one patient was hypertensive at the time of CT perfusion. Scans showed diffuse cerebral hypoperfusion, more pronounced in the corona radiata and areas with brain edema. No patient had critical cerebral ischemia or arterial vasoconstriction on CT angiogram.

CONCLUSIONS

Patients with PRES can have cerebral hypoperfusion despite severe hypertension. A perfusion study in the acute setting may be helpful to better understand the perfusion status and guide blood pressure treatment.

Clinical application of brain perfusion imaging in detecting stroke mimics: A review

Stroke mimics constitute a significant proportion of patients with suspected acute ischemic stroke. These conditions may resemble acute ischemic stroke and demonstrate abnormalities on perfusion imaging sequences. The most common stroke mimics include seizure/epilepsy, migraine with aura, brain tumors, functional disorders, infectious encephalopathies, Wernicke's encephalopathy, and metabolic abnormalities. Brain perfusion imaging techniques, particularly computed tomography perfusion and magnetic resonance perfusion, are being widely used in routine clinical practice for treatment selection in patients presenting with large vessel occlusion. At the same time, the utilization of these imaging modalities enables the opportunity to better diagnose patients with stroke mimics in a time-sensitive setting, leading to appropriate management, decision-making, and resource allocation. In this review, we describe patterns of perfusion abnormalities that could discriminate patients with stroke mimics from those with acute ischemic stroke and provide specific case examples to illustrate these perfusion abnormalities. In addition, we discuss the challenges associated with interpretation of perfusion images in stroke-related pathologies. In general, perfusion imaging can provide additional information in some cases-when used in combination with conventional magnetic resonance imaging and computed tomography-and might help in detecting stroke mimics among patients who present with acute onset focal neurological symptoms.

Cerebral perfusion in posterior reversible encephalopathy syndrome measured with arterial spin labeling MRI

BACKGROUND AND PURPOSE

The pathophysiologic basis of posterior reversible encephalopathy syndrome (PRES) remains controversial. Hypertension (HTN)-induced autoregulatory failure with subsequent hyperperfusion is the leading hypothesis, whereas alternative theories suggest vasoconstriction-induced hypoperfusion as the underlying mechanism. Studies using contrast-based CT and MR perfusion imaging have yielded contradictory results supporting both ideas. This work represents one of the first applications of arterial spin labeling (ASL) to evaluate cerebral blood flow (CBF) changes in PRES.

MATERIALS AND METHODS

After obtaining Institutional Review Board approval, MRI reports at our institution from 07/2015 to 09/2020 were retrospectively searched and reviewed for mention of "PRES" and "posterior reversible encephalopathy syndrome." Of the resulting 103 MRIs (performed on GE 1.5 Tesla or 3 Tesla scanners), 20 MRIs in 18 patients who met the inclusion criteria of clinical and imaging diagnosis of PRES and had diagnostic-quality pseudocontinuous ASL scans were included. Patients with a more likely alternative diagnosis, technically non-diagnostic ASL, or other intracranial abnormalities limiting assessment of underlying PRES features were excluded. Perfusion in FLAIR-affected brain regions was qualitatively assessed using ASL and characterized as hyperperfusion, normal, or hypoperfusion. Additional quantitative analysis was performed by measuring average gray matter CBF in abnormal versus normal brain regions.

RESULTS

HTN was the most common PRES etiology (65%). ASL showed hyperperfusion in 13 cases and normal perfusion in 7 cases. A hypoperfusion pattern was not identified. Quantitative analysis of gray matter CBF among patients with visually apparent hyperperfusion showed statistically higher perfusion in affected versus normal appearing brain regions (median CBF 100.4 ml/100 g-min vs. 61.0 ml/ 100 g-min, p < 0.001).

CONCLUSION

Elevated ASL CBF was seen in the majority (65%) of patients with PRES, favoring the autoregulatory failure hypothesis as a predominant mechanism. Our data support ASL as a practical way to assess and noninvasively monitor cerebral perfusion in PRES that could potentially alter management strategies.

Added Value of Arterial Spin Labeling in Detecting Posterior Reversible Encephalopathy Syndrome as a Stroke Mimic on Baseline Neuroimaging: A Single Center Experience

Differentiating stroke from stroke mimics is a diagnostic challenge in every day practice. Posterior Reversible Encephalopathy Syndrome (PRES) is an important stroke mimic with nonspecific symptomatology, making prompt and accurate diagnosis challenging. Baseline neuroimaging plays a pivotal role in detection and differentiation of stroke from many common mimics and is thus critical in guiding appropriate management. In particular, MR perfusion (MRP) imaging modalities provide added value through detection and quantification of multiple physiological parameters. Arterial Spin Labeling (ASL) is a non-contrast, noninvasive MRP technique increasingly used in clinical practice; however, there is limited description of ASL in PRES in the existing literature. In this single center retrospective pilot study, we investigate the added value of ASL in detecting PRES in the largest series to date. We hope this study can serve as the basis for larger scale investigations exploring the utility of ASL in detecting stroke mimics such as PRES for accurate and efficient management of such patients.

Toxic and metabolic leukoencephalopathies in emergency department patients: a primer for the radiologist

One of the most common chief complaints in the emergency department (ED) is altered mental status (AMS). Imaging plays a critical role in triaging patients and identifying the etiology of AMS. Toxic and metabolic etiologies are one of the primary differential categories for AMS, leading to toxic leukoencephalopathies. Toxic leukoencephalopathies are white matter disorders that result from either exogenous or endogenous sources. Common exogeneous causes of toxic leukoencephalopathy include drugs of abuse (heroin and cocaine), alcohol, inhaled gases (carbon monoxide), industrial agents (pesticides, toluene, ethylene glycol), and neurotoxic medications (methotrexate, metronidazole, vigabatrine, etc.); endogenous causes include hyper- and hypoglycemia, hyperammonemia, hyponatremia, and uremia. The imaging findings of toxic leukoencephalopathies manifest through a combination of vasogenic and cytotoxic edema, resulting in white matter patterns. These white matter patterns have been found to be pathognomonic. In the ED setting, it is imperative to develop a diagnosis based off of the imaging due to the lack of history and context that is typically provided with a chief complaint of altered mental status (AMS). To offer expeditious and accurate diagnosis, we present the classic imaging features of toxic leukoencephalopathies and correlate these imaging findings with pathophysiology.

Stroke Mimics in the Acute Setting: Role of Multimodal CT Protocol

BACKGROUND AND PURPOSE

Ischemic stroke can be mimicked by nonischemic conditions. Due to emphasis on the rapid treatment of acute ischemic stroke, it is crucial to identify these conditions to avoid unnecessary therapies and potential complications. We investigated the performance of the multimodal CT protocol (unenhanced brain CT, CTA, and CTP) to discriminate stroke mimics from acute ischemic stroke.

MATERIALS AND METHODS

We retrospectively selected multimodal CT studies performed for clinical suspicion of acute ischemic stroke in our center in a 24-month period, including patients with at least 1 follow-up imaging study (brain CT or MR imaging). Hemorrhagic strokes were excluded. We measured the performance of multimodal CT, comparing the original diagnostic results with the final clinical diagnosis at discharge.

RESULTS

Among 401 patients, a stroke mimic condition was diagnosed in 89 (22%), including seizures (34.8%), migraine with aura attack (12.4%), conversion disorder (12.4%), infection (7.9%), brain tumor (7.9%), acute metabolic condition (6.7%), peripheral vertigo (5.6%), syncope (5.6%), transient global amnesia (3.4%), subdural hematoma (1.1%), cervical epidural hematoma (1.1%), and dural AVF (1.1%). Multimodal CT sensitivity, specificity, and accuracy were 24.7%, 99.7%, and 83%. Multimodal CT revealed peri-ictal changes in 13/31 seizures and diagnosed 7/7 brain tumors, 1/1 dural AVF, and 1/1 subdural hematoma. CT perfusion played a pivotal diagnostic role.

CONCLUSIONS

Multimodal CT demonstrated low sensitivity but high specificity in the diagnosis of stroke mimics in the acute setting. The high specificity of multimodal CT allows ruling out stroke and thereby avoiding unnecessary revascularization treatment in patients with diagnosis of a stroke mimic.

Cerebrovascular Disease in the Setting of Posterior Reversible Encephalopathy Syndrome

Overlap between the pathogenesis of posterior reversible encephalopathy syndrome and that of cerebrovascular disease can confound their clinical and radiological presentations, posing a diagnostic challenge. This article presents a literature review and discussion of the clinical manifestations, pathological mechanisms, and imaging manifestations of subarachnoid hemorrhage and vasculitis leading to posterior reversible encephalopathy syndrome, coexistence of posterior reversible encephalopathy syndrome with reversible cerebral vasoconstriction syndrome, and hemorrhage and infarction secondary to posterior reversible encephalopathy syndrome. The findings show that posterior reversible encephalopathy syndrome shares some overlapping pathophysiological mechanisms with cerebrovascular disease. Importantly, neuroimaging plays an important role in identifying this entity in a timely manner and differentiating it from other diseases.

Clinical characteristics and perfusion-computed tomography alterations in a series of patients with migraine with aura attended as stroke code

OBJECTIVE

The aim of the current study was to determine the clinical characteristics of migraine with aura (MA) as well as the frequency and patterns of perfusion-computed tomography (PCT) alterations, in a series of patients with MA mimicking acute ischemic stroke.

BACKGROUND

MA is one of the most frequent stroke mimics, following seizures and psychiatric disorders. Previous case reports and short series have reported abnormal PCT patterns in patients with MA.

METHODS

We conducted a retrospective cohort study including all consecutive patients presenting with focal neurological symptoms during complete multimodal CT including baseline CT, angio-CT, and PCT with a final diagnosis of MA. We collected demographic data and clinical information about MA variables using the hospital electronic database.

RESULTS

We found 25 patients with a final diagnosis of MA among 1761 patients who attended our stroke center with complete multimodal CT (1.4% [95% CI: 0.9-2.1]). Among them, 14/25 (56%) were women, average age 38.7 years (SD 12.5), and 16/25 (64%) had a previous history of migraine. The most frequent type of aura was sensory. The median time elapsed between the onset of symptoms and CT was 171 min (IQR: 119-244). PCT alteration was found in 3/25 (12%) consisting of a hypoperfusion pattern not restricted to a vascular territory. The three patients had aphasia as the presenting symptom.

CONCLUSION

This is, to the best of our knowledge, the largest series of patients with MA managed as presumed stroke with clinical characteristics and PCT. In our study, most patients were young and had a prior history of migraine. PCT was normal in 88% of cases, with patients being still symptomatic by the time they were scanned. Further research will clarify the presence and type of PCT alterations in this entity.

Posterior Reversible Encephalopathy Syndrome: A Narrative Review for Emergency Clinicians

BACKGROUND

Posterior reversible encephalopathy syndrome (PRES) is a clinicoradiologic disorder characterized by seizures, headache, altered mental status, and visual disturbances, and is often associated with acute hypertension.

OBJECTIVE

This narrative review provides a focused description of the presentation, diagnostic evaluation, and management of PRES.

DISCUSSION

PRES is associated with a variety of factors, including acute rise in blood pressure, renal disease, preeclampsia/eclampsia, and immunosuppressive therapy. The pathophysiology is theorized to involve dysfunction of cerebral autoregulation leading to vascular leak or endothelial dysfunction resulting in vasogenic edema. In the emergency department (ED), clinical findings suggestive of PRES should prompt diagnostic testing focused on confirming the diagnosis and excluding other conditions that may present similarly. Laboratory studies are primarily useful for excluding alternative diagnoses. Computed tomography (CT) and, in particular, magnetic resonance imaging (MRI) are the recommended neuroimaging modalities for diagnosis. CT and MRI may demonstrate cerebral vasogenic edema, most often in the distribution of the posterior circulation. Treatment involves management of seizures, control of blood pressure if elevated, and treatment of any underlying trigger.

CONCLUSION

PRES is a neurological disorder that is typically reversible if recognized on presentation and promptly and appropriately managed. This narrative review characterizes this condition for emergency clinicians.

Automated Brain Perfusion Imaging in Acute Ischemic Stroke: Interpretation Pearls and Pitfalls

Recent advancements in computed tomography technology, including improved brain coverage and automated processing of the perfusion data, have reinforced the use of perfusion computed tomography imaging in the routine evaluation of patients with acute ischemic stroke. The DAWN (Diffusion Weighted Imaging or Computerized Tomography Perfusion Assessment With Clinical Mismatch in the Triage of Wake Up and Late Presenting Strokes Undergoing Neurointervention) and DEFUSE 3 (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke 3) trials have established the benefit of endovascular thrombectomy in patients with acute ischemic stroke with anterior circulation large vessel occlusion up to 24 hours of last seen normal, using perfusion imaging-based patient selection. The compelling data has prompted stroke centers to increasingly introduce automated perfusion computed tomography imaging in the routine evaluation of patients with acute ischemic stroke. We present a comprehensive overview of the acquisition and interpretation of automated perfusion imaging in patients with acute ischemic stroke with a special emphasis on the interpretation pearls, pitfalls, and stroke mimicking conditions.

Unusual Presentation of a Posterior Reversible Encephalopathy Syndrome With Brainstem Involvement and Subarachnoid Haemorrhage

Posterior reversible encephalopathy syndrome is an increasingly recognized disorder characterized by a headache, visual disturbances, and seizures. It is a reversible neurotoxic state, with multiple risk factors in which endothelial injury and compromised brain perfusion are the common characteristics. Diagnosis is usually made by cerebral magnetic resonance imaging that typically shows early-stage bilateral symmetrical parieto-occipital hyperintensities on T2 and fluid-attenuated inversion recovery (FLAIR) sequences. However, other locations have been described where the disease may appear less frequently. We describe the case of a 62-year-old man, with a medical history of hypertension, who presented with anisocoria with mydriatic non-reactive pupil and ptosis of the left eye. CT head showed a slightly hypodense brainstem, in relation to vasogenic edema. This was confirmed with magnetic resonance imaging. The angiography did not identify cerebral artery aneurysms. The symptoms and radiological findings were almost completely reversible after improving the patient's blood pressure. This case highlights a rare single presentation of posterior reversible encephalopathy syndrome associated with subarachnoid hemorrhage. A high index of suspicion, careful examination, and exploration with imaging techniques were essential to reach this diagnosis.

Current perspectives on neuroimaging techniques used to identify stroke mimics in clinical practice

INTRODUCTION

Urgent clinical assessment and brain imaging are essential for differentiating stroke mimics from stroke and to avoid unnecessary initiation of reperfusion and other therapies in stroke mimic patients.

AREAS COVERED

In this article, the authors will review acute stroke imaging and then the imaging patterns of the most common stroke mimics. The authors have focused our review on brain CT scan, and more specifically CT perfusion, as this is the most commonly available and emerging tool in emergency settings. The authors also provide information on acute brain MRI and MR perfusion.

EXPERT OPINION

Imaging can contribute to the detection and diagnosis of acute stroke mimics. Knowledge of imaging findings in different stroke mimics can help distinguish these from patients with stroke who require timely reperfusion therapy. CT and MRI perfusion and diffusion-weighted imaging (DWI) MRI are useful imaging modalities for the assessment of acute stroke patients as they provide more accurate information than plain CT scan. Some of these modalities should be available in the emergency setting. The authors recommended CT perfusion as a useful tool for stroke management and differentiation with stroke mimics.

Predictors of perfusion computed tomography alterations in stroke mimics attended as stroke code

BACKGROUND AND PURPOSE

Stroke mimics (SMs) account for a significant number of patients attended as stroke code (SC) with an increasing number over the years. Recent studies show perfusion computed tomography (PCT) alterations in some SMs, especially in seizures. The objective of our study was to evaluate the clinical characteristics and PCT alterations in SMs attended as SC in order to identify potential predictors of PCT alterations in SMs.

METHODS

A retrospective study was performed including all SC activations undergoing a multimodal CT study including non-enhanced computed tomography (CT), CT angiography and PCT, as part of our SC protocol, over 39 months. Patients with a final diagnosis of SM after complete diagnosis work-up were therefore selected. Clinical variables, diagnosis, PCT alteration patterns and type of map affected (T_max or time to peak, cerebral blood flow and cerebral blood volume) were registered.

RESULTS

Stroke mimics represent up to 16% (284/1761) of SCs with a complete multimodal study according to our series. Amongst SMs, 26% (74/284) showed PCT alterations. PCT abnormalities are more prevalent in seizures and status epilepticus and the main pattern is alteration of the time to peak map, of unilateral hemispheric distribution or of non-vascular territory. In our series, the independent predictors of alteration in PCT in SMs are aphasia, female sex and older age.

CONCLUSIONS

Perfusion computed tomography alterations can be found amongst almost a third of SMs attended as SC, especially older women presenting with aphasia with a final diagnosis of epileptic seizures and status epilepticus.

Posterior Reversible Encephalopathy Syndrome After Transsphenoidal Resection of Pituitary Macroadenoma

BACKGROUND

Posterior reversible encephalopathy syndrome is manifested by a reversible neurologic deficit such as vision loss, encephalopathy, and a posterior location, typically the occipital lobes. It is commonly thought to be related to acute, severe hypertension.

CASE DESCRIPTION

A 51-year-old woman presented with visual loss for several months, and a suprasellar mass was diagnosed. She underwent transsphenoidal surgery, which was complicated by cerebrospinal fluid leak, and she developed posterior reversible encephalopathy syndrome while undergoing postoperative cerebrospinal fluid drainage via lumbar catheter. Her visual acuity progressed to blindness, but blindness was reversed by discontinuation of lumbar drainage, tight blood pressure control, and high-dose steroid drip.

CONCLUSIONS

To our knowledge, this is only the second case of posterior reversible encephalopathy syndrome following transsphenoidal surgery to be reported in the neurosurgical or ophthalmic English language literature.

Altered and Agitated due to Hypertension: A Case of Posterior Reversible Encephalopathy Syndrome

The authors present a case of posterior reversible encephalopathy syndrome in a patient on nutritional supplements. The presentation and emergency management are discussed.

Cerebrospinal Fluid Hypovolemia and Posterior Reversible Encephalopathy Syndrome

Posterior reversible encephalopathy syndrome (PRES) is a reversible neuroradiological syndrome characterized by reversible vasogenic edema. The pathophysiological mechanism is still unclear, but PRES may be triggered by various etiologies. To date, only a few PRES cases linked to cerebrospinal fluid (CSF) hypovolemia were reported. The association between PRES and CSF hypovolemia needs to be explored. We presented a case of PRES with CSF hypovolemia as a result of an inadvertent dural puncture and reviewed the literature to identify the clinical characterization and pathophysiological mechanism of PRES following CSF hypovolemia. A total of 31 cases of PRES-CSF hypovolemia was included for analysis. The median age was 33 years, with a notable female predominance (87.1%). Fifteen patients (48.4%) didn't have either a history of hypertension nor an episode of hypertension. The most common cause of CSF hypovolemia was epidural or lumbar puncture (n = 21), followed by CSF shunt (n = 6). The median interval between the procedure leading to CSF hypovolemia and PRES was 4 days. Seizure, altered mental state, and headache were the most frequent presenting symptom. The parietooccipital pattern was most frequent (71.0%). Conservative management remains the mainstay of treatment with excellent outcomes. Three patients had a second episode of PRES. CSF hypovolemia is a plausible cause of PRES via a unique pathophysiologic mechanism including arterial hyperperfusion and venous dysfunction. Patients with CSF hypovolemia is more susceptible to PRES, which is potentially life-threatening. Given that CSF hypovolemia is a common complication of anesthetic, neurological, and neurosurgical procedures, PRES should be early considered for prompt diagnosis and appropriate management.

Characteristics of Perfusion Computed Tomography Imaging in Patients with Seizures Mimicking Acute Stroke

Introduction: Seizures as acute stroke mimics are a diagnostic challenge. Objective: The aim of the study was to characterize the perfusion patterns on perfusion computed tomography (PCT) in patients with seizures masquerading as acute stroke. Methods: We conducted a study on patients with acute seizures as stroke mimics. The inclusion criteria for this study were patients (1) initially presenting with stroke-like symptoms but finally diagnosed to have seizures and (2) with PCT performed within 72 h of seizures. The PCT of seizure patients (n = 27) was compared with that of revascularized stroke patients (n = 20) as the control group. Results: Among the 27 patients with seizures as stroke mimics, 70.4% (n = 19) showed characteristic PCT findings compared with the revascularized stroke patients, which were as follows: (1) multi-territorial cortical hyperperfusion {(73.7% [14/19] vs. 0% [0/20], p = 0.002), sensitivity of 73.7%, negative predictive value (NPV) of 80%}, (2) involvement of the ipsilateral thalamus {(57.9% [11/19] vs. 0% [0/20], p = 0.007), sensitivity of 57.9%, NPV of 71.4%}, and (3) reduced perfusion time {(84.2% [16/19] vs. 0% [0/20], p = 0.001), sensitivity of 84.2%, NPV of 87%}. These 3 findings had 100% specificity and positive predictive value in predicting patients with acute seizures in comparison with reperfused stroke patients. Older age was strongly associated with abnormal perfusion changes (p = 0.038), with a mean age of 66.8 ± 14.5 years versus 49.2 ± 27.4 years (in seizure patients with normal perfusion scan). Conclusions: PCT is a reliable tool to differentiate acute seizures from acute stroke in the emergency setting.

Advanced Imaging Techniques in Diagnosis of Posterior Reversible Encephalopathy Syndrome (PRES)

Diagnosis of Posterior Reversible Encephalopathy Syndrome (PRES) in some circumstances can be challenging and structural imaging may not be sufficient to distinguish it from other differential diagnostic considerations. Advanced imaging techniques, such as MR spectroscopy or positron emission tomography (PET) can provide additional information to determine the diagnosis. Other techniques, such as susceptibility weighted imaging (SWI) improves detection of hemorrhage which has prognostic role. CT or MR Perfusion as well as Single-Photon Emission Computed Tomography (SPECT) are more useful to understand the underlying vasculopathic changes in PRES and may answer some of the unresolved controversies in pathophysiology of this complex disease. In this review we summarized the findings of previous studies using these advanced methods and their utilities in diagnosis or prognosis of PRES.

Unusual Delayed Presentation of Posterior Reversible Encephalopathy Syndrome Following Vestibular Schwannoma Surgery: A Rare Neurologic Emergency

BACKGROUND

Posterior reversible encephalopathy syndrome (PRES) is a rare neurologic condition that manifests with heterogeneous clinical findings, including altered mental status, seizure, vision loss, and vomiting. It characteristically leads to diffuse subcortical vasogenic edema, most commonly in the parieto-occipital regions. Although frequently reported with conditions such as hypertension, eclampsia, sepsis, electrolyte imbalances, autoimmune diseases, and immunosuppressive therapy, PRES may rarely occur after surgery for posterior fossa tumors. In the postsurgical setting, clinical features of PRES usually develop intraoperatively or in the immediate postoperative period. Delayed presentation months after the surgery has not been reported earlier.

CASE DESCRIPTION

A 23-year-old woman who underwent surgery for vestibular schwannoma 8 months earlier presented with altered sensorium, generalized seizures, and high blood pressure. Common possibilities were ruled out by clinical history, diagnostic imaging, and appropriate blood tests. Radiologic imaging revealed rapid recurrence of tumor with diffuse subcortical edema involving both hemispheres. The patient showed complete neurologic recovery with antihypertensive and antiepileptic drugs.

CONCLUSIONS

PRES is a rare but important cause of acute neurologic deterioration following posterior fossa tumor surgery. Prompt diagnosis and aggressive treatment often lead to complete neurologic recovery.

Posterior Reversible Encephalopathy Syndrome Presenting as Stroke Mimic

We present the case of a 33-year-old male with end stage renal disease presenting to the emergency department (ED) with headache, dizziness, and unilateral weakness. Initial concern was for ischemic or hemorrhagic stroke. Magnetic resonance imaging confirmed posterior reversible encephalopathy syndrome (PRES). The patient was treated appropriately and made a full neurologic recovery. PRES is an under-recognized diagnosis in the ED. As a stroke mimic, PRES can lead the clinician on an incorrect diagnostic pathway with potential for iatrogenic harm.

Posterior reversible encephalopathy syndrome following sepsis in a Crohn’s disease patient: A case report

Posterior reversible encephalopathy syndrome (PRES) is a clinico-ragiological syndrome presenting with neurological symptoms and characteristic radiologic findings. PRES occurs in the setting of various clinical conditions and requires prompt management of the causative factor for a full recovery. This is a case report of a Crohn’s disease patient who developed PRES syndrome during a complicated post-operative course. In the presence of multiple causative factors, sepsis was considered as the predominant one. After prompt management, the patient recovered with no permanent neurological damage.

Posterior reversible encephalopathy syndrome with thalamic involvement during vasopressor treatment of vertebrobasilar vasospasm after subarachnoid hemorrhage

Hemodynamic augmentation is the primary medical intervention employed to reverse neurological deficits associated with vasospasm and delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage. Failure to improve despite induced hypertension (IH) may raise concern for persistent hypoperfusion and prompt even more aggressive blood pressure augmentation. However, posterior reversible encephalopathy syndrome (PRES) is a hyperperfusion syndrome reported as a rare complication of IH that may confound this picture. We report a case of PRES with prominent thalamic involvement and impaired level of consciousness secondary to blood pressure augmentation for the treatment of symptomatic vertebrobasilar vasospasm. Recognition of this syndrome in distinction to worsening ischemia is particularly critical, as normalization of blood pressure should lead to rapid clinical improvement.

Posterior reversible encephalopathy syndrome with thalamic involvement during vasopressor treatment of vertebrobasilar vasospasm after subarachnoid hemorrhage

Hemodynamic augmentation is the primary medical intervention employed to reverse neurological deficits associated with vasospasm and delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage. Failure to improve despite induced hypertension (IH) may raise concern for persistent hypoperfusion and prompt even more aggressive blood pressure augmentation. However, posterior reversible encephalopathy syndrome (PRES) is a hyperperfusion syndrome reported as a rare complication of IH that may confound this picture. We report a case of PRES with prominent thalamic involvement and impaired level of consciousness secondary to blood pressure augmentation for the treatment of symptomatic vertebrobasilar vasospasm. Recognition of this syndrome in distinction to worsening ischemia is particularly critical, as normalization of blood pressure should lead to rapid clinical improvement.

Epileptic Ictal Hyperperfusion on Arterial Spin Labeling Perfusion and Diffusion-Weighted Magnetic Resonance Images in Posterior Reversible Encephalopathy Syndrome

BACKGROUND

The hemodynamic state of the posterior dominant vasogenic edema in posterior reversible encephalopathy syndrome (PRES) is controversial. The aim of this retrospective study was to examine the contribution of epileptic ictal hyperperfusion in patients with PRES using combined magnetic resonance perfusion imaging with arterial spin labeling (ASL) and diffusion-weighted magnetic resonance imaging (MRI).

METHODS

A detailed review of chronological MRI findings in 2 patients, including diffusion-weighted imaging (DWI) and ASL, with special reference to clinical and electroencephalographic findings, was performed. At the onset of PRES, both patients developed secondary generalized seizures.

RESULTS

At the first PRES episode in Case 1, ASL and DWI clearly depicted "ictal hyperperfusion" and prolonged epilepsy-induced cytotoxic edema in the left parieto-occipital lobe cortex, located around the vasogenic edema of the PRES lesion in the left occipital lobe (hypoperfused area). At the second and third episodes (2 and 7 months after the first episode, respectively), although recurrent PRES was ruled out, ASL and DWI clearly demonstrated ictal hyperperfusion in the left posterior temporal and parieto-occipital lobes associated with partial nonconvulsive status epilepticus, which developed around the PRES-related old hematoma lesion. In Case 2, peri-ictal MRI findings of ictal ASL hyperperfusion and cortical hyperintensity on DWI were also noted in the left parieto-occipital lobe, but were mild compared with Case 1.

CONCLUSIONS

Combined use of DWI and ASL can provide information on hemodynamic state associated with epileptic ictal hyperperfusion in the various phases of PRES.

Posterior reversible encephalopathy syndrome

Posterior reversible encephalopathy syndrome (PRES) is a complex disorder, our understanding of which continues to evolve. PRES has many clinical associations, many causative factors, a variety of imaging manifestations, and its pathophysiology remains a topic of debate. There are also many other disorders that may mimic PRES. We present a concise review of PRES to enable the radiologist to more readily and easily recognize this treatable disorder with important clinical implications.

Cerebral Hypoperfusion in Posterior Reversible Encephalopathy Syndrome is Different from Transient Ischemic Attack on CT Perfusion

BACKGROUND

PRES is a reversible neurotoxic state presenting with headache, altered mental status, visual loss, and seizures. Delayed diagnosis can be avoided if radiological patterns could distinguish PRES from cerebral ischemia.

METHODS

Clinical and radiological data were collected on all hospitalized patients who had (1) discharge diagnosis of PRES and (2) acute CTP/CTA. Data were compared with 10 TIA patients with proven cytotoxic edema on MRI.

RESULTS

Of the four PRES patients found, three were correlated with acute blood pressure and one with chemotherapy. At the radiological level, quantitative analyses of the CTP parameters showed that 2 out of 4 patients had bilaterally reduced CBF-values (23.2-47.1 ml/100g/min) in occipital regions, as seen in the pathological regions of TIA patients (27.3 ± 13.5 ml/100g/min). When compared with TIA patients, the pathological ROI's demonstrated decreased CBV-values (3.4-5.6 ml/100g). Vasogenic edema on MRI FLAIR imaging was seen in only one PRES patient, and cytotoxic edema on DWI-imaging was never found. CT angiography showed in one PRES patient a vasospasm-like unilateral posterior cerebral artery.

CONCLUSIONS

If confirmed by other groups, CTP and CTA imaging in patients with acute visual loss and confusion may help to distinguish PRES from bi-occipital ischemia. These radiological parameters may identify PRES patients at risk for additional tissue infarction.

Confounding psychosis in the postpartum period

This case report alerts the psychiatric clinician to consider nonpsychiatric etiologies of psychosis appearing during the postpartum period besides postpartum psychosis. The case includes a description of the patient's psychiatric presentation, admission to the inpatient psychiatric unit with subsequent transfer to the medicine department including neuroimaging and neurological consultation. The patient had a remission of psychosis after only two and half days of antipsychotic medication administration. Positive findings on the MRI suggested a demyelinating disease and a 4-month follow up MRI continued to be positive. The etiology was presumed to be a demyelinating disease. In conclusion, psychiatrists need to be alert to include nonpsychiatric pathologies in the differential diagnosis when a patient presents with psychosis in the postpartum period.

Tacrolimus associated posterior reversible encephalopathy syndrome - a case series and review

Tacrolimus is an immunosuppressive drug mainly used to lower the risk of transplant rejection in individuals who are post solid organ or hematopoietic transplantation. It is a macrolide which reduces peptidyl-propyl isomerase activity and inhibits calcineurin, thus inhibiting T-lymphocyte signal transduction and interleukin-2 (IL-2) transcription. It has been associated with Posterior Reversible Encephalopathy Syndrome (PRES), a disease of sudden onset that can present as a host of different symptoms, depending on the affected area of the brain. While infectious causes of encephalopathy must always be entertained, the differential diagnosis should also include PRES in the appropriate context. We report three cases of PRES in patients with acute myeloid leukemia (AML) placed on tacrolimus after receiving a bone marrow transplant (BMT). The focus of this review is to enhance clinical recognition of PRES as it is related to an adverse effect of Tacrolimus in the setting of hematopoietic transplantation.

Polyarteritis nodosa complicated by posterior reversible encephalopathy syndrome: a case report

Background

Posterior reversible encephalopathy syndrome is a presentation which is diagnosed clinico-radiologically. The primary aetiological processes leading to posterior reversible encephalopathy syndrome are many, which include autoimmune conditions. Polyarteritis nodosa as an aetiological factor for posterior reversible encephalopathy syndrome is rare. We present a case of polyarteritis nodosa complicated by posterior reversible encephalopathy syndrome.

Case presentation

A 26-year-old South-Asian female presented with left sided focal seizures with secondary generalization and visual disturbance for 2 days duration. She had a prior history of arthralgia and weight loss with no medically explainable cause for young onset hypertension. Examination revealed a right claw hand with a palpable vasculitic type of rash involving both the palmar surfaces. Symptoms responded to management with anti-hypertensives and anti-epileptics. Whole blood count, iron studies, erythrocyte sedimentation rate and C-reactive protein values portrayed an ongoing chronic inflammatory process. Serological studies such as Anti-nuclear antibody, Anti -double stranded deoxyribonucleic acid, Anti-neutrophil cytoplasmic antibody and Anti-cyclic citrulinated peptide were negative. Magnetic resonance imaging revealed high signal intensity on T2 in both occipital lobes. Skin biopsy of the palm revealed moderate vessel vasculitis. Renal imaging revealed structurally abnormal kidneys with micro aneurysms in the right renal vasculature. Repeat magnetic resonance imaging of the brain two months later showed marked improvement. A diagnosis of polyarteritis nodosa with posterior reversible encephalopathy syndrome was made.

Conclusions

Posterior reversible encephalopathy syndrome should not be missed. Investigations for an aetio-pathological cause should be considered including the rarer associations like polyarteritis nodosa.

Use of perfusion imaging and other imaging techniques to assess risks/benefits of acute stroke interventions

The advent of multimodal neuroimaging has provided acute stroke care providers with an armamentarium of sophisticated imaging options to utilize for guidance in clinical decision-making and management of acute ischemic stroke patients. Here, we propose a framework and potential algorithm-based methodology for imaging modality selection and utilization for the purpose of achieving optimal stroke clinical care. We first review imaging options that may best inform decision-making regarding revascularization eligibility, with a focus on the imaging modalities that best identify critical inclusion and exclusion criteria. Next, we review imaging methods that may guide the successful achievement of revascularization once it has been deemed desirable and feasible. Further, we review imaging modalities that may best assist in both the noninterventional care of acute stroke as well as the identification of stroke-mimics. Finally, we review imaging techniques under current investigation that show promise to improve future acute stroke management.

Cortical Laminar Necrosis and CT Negative Hemorrhage in Posterior Reversible Encephalopathy Syndrome. A Case Report

Posterior reversible encephalopathy syndrome (PRES) is a clinicoradiologic condition that typically demonstrates symmetric occipitoparietal vasogenic edema on CT and MR imaging. The vasogenic edema typically resolves over a period of days to weeks if the underlying hemodynamic abnormality is promptly corrected. Less commonly, PRES may be complicated by hemorrhage or cytotoxic edema that restricts diffusion and usually involves the cerebral cortex. Cortical laminar necrosis (CLN) is a sequela of cerebral energy depletion, resulting in selective necrosis of the most metabolically active cortical layers. Cortical hemorrhage is an atypical feature of CLN. We present a unique PRES case with imaging features of both CLN and CT negative hemorrhage. CLN with CT negative hemorrhage in the setting of PRES has not been previously reported to the best of our knowledge.