Posterior reversible encephalopathy syndrome: incidence of atypical regions of involvement and imaging findings

Posterior reversible encephalopathy syndrome mimicking a cerebral tumour

Posterior reversible encephalopathy syndrome (PRES) is a syndrome characterised clinically by headache, confusion, seizures, vomiting and visual disturbances with radiographic vasogenic oedema. CT imaging is typically normal, non-specific or suggestive of PRES or stroke. MRI usually shows symmetrical parietal and occipital lobe vasogenic oedema. The authors discuss a 58-year-old man presenting with right homonymous haemianopia, hypertension and ataxia. CT imaging suggested a left occipital lobe space occupying lesion (SOL). Surprisingly, subsequent contrast enhanced MRI showed characteristic bilateral vasogenic oedema in occipital and temporal lobes indicative of PRES. Hypertension, an associated predisposing factor, was present in this case and symptoms improved with antihypertensive therapy. This case highlights PRES may present with asymmetrical CT imaging findings mimicking a SOL. PRES is a potentially reversible condition with prompt treatment. MRI is essential in diagnosing both PRES and the cause of acute visual loss.

What the emergency radiologist needs to know about treatment-related complications from conventional chemotherapy and newer molecular targeted agents

Emergency departments (ED) are increasingly utilized by oncology patients for disease- and treatment-related issues. With the increased use of new molecular targeted therapy (MTT) and conventional chemotherapeutic regimens, oncology patients present with a range of adverse treatment effects, some of which reveal characteristic injury patterns and imaging appearances. Knowledge of these imaging findings is critically important for early detection and prompt management in oncology patients. In this article, we present a brief review of conventional chemotherapeutic and new MTT regimens as well as address adverse reactions that bring oncology patients to the ED.

Posterior reversible encephalopathy syndrome presenting as Balint syndrome

Balint syndrome is a disorder of inaccurate visually guided saccades, optic ataxia, and simultanagnosia that typically results from bilateral parieto-occipital lesions. Visual perception disturbances in the posterior reversible encephalopathy syndrome (PRES) include hemianopia, visual neglect, and cerebral blindness, but Balint syndrome had not been recognized. We report Balint syndrome associated with PRES in a 37-year-old woman with acute hypertension and systemic lupus erythematosus. Balint syndrome can be an initial presentation of PRES.

Side effects of oncologic therapies in the pediatric central nervous system: update on neuroimaging findings

The need for early, accurate diagnosis of central nervous system (CNS) complications occurring during and after pediatric cancer treatment is growing because of the improvement in overall survival rates related to innovative and aggressive oncologic therapies. An elevated degree of suspicion is needed to recognize the radiologic features of these CNS complications. Radiologists need familiarity with the early and late side effects of cancer therapy in the pediatric CNS (eg, toxic effects, infection, endocrine or sensory dysfunction, neuropsychologic impairment, second malignancies), in order to accelerate the imaging diagnosis and minimize as much as possible the associated morbidity. Acquisition of knowledge about these complications will enable the development of more appropriate therapeutic trials and more effective patient surveillance and will lead to an improved quality of life by decreasing the long-term sequelae in survivors.

Posterior reversible encephalopathy syndrome (PRES) and CT perfusion changes

Posterior reversible encephalopathy syndrome (PRES) can present with focal neurologic deficits, mimicking a stroke and can often represent a diagnostic challenge when presenting atypically. A high degree of suspicion is required in the clinical setting in order to yield the diagnosis. Cerebral CT perfusion (CTP) is utilized in many institutions as the first line in acute stroke imaging. CTP has proved to be a very sensitive measure of cerebral blood flow dynamics, most commonly employed to delineate the infarcted tissue from penumbra (at-risk tissue) in ischemic strokes. But abnormal CTP is also seen in stroke mimics such as seizures, hypoglycemia, tumors, migraines and PRES. In this article we describe a case of PRES in an elderly bone marrow transplant recipient who presented with focal neurological deficits concerning for a cerebrovascular accident. CTP played a pivotal role in the diagnosis and initiation of appropriate management. We also briefly discuss the pathophysiology of PRES.

Detection of microhemorrhage in posterior reversible encephalopathy syndrome using susceptibility-weighted imaging

BACKGROUND AND PURPOSE

PRES-related vasogenic edema is potentially reversible while hemorrhage occurs in only 15.2%-17.3% of patients. However, the true incidence of hemorrhage could be higher when SWI is considered. Thus, we set out to determine the incidence of MH, SAH, and IPH in PRES by using SWI and to particularly evaluate whether such MHs are reversible.

MATERIALS AND METHODS

Thirty-one patients with PRES and SWI were included, 17 having follow-up SWI. Two neuroradiologists reviewed SWI, FLAIR, DWI, and CE-T1WI. The presence and number of MHs (<5 mm) on SWI, SAH, and IPH (>5 mm) were recorded at presentation and follow-up. We evaluated associations between the presence of MH on SWI and DWI lesions, SAH, IPH, contrast enhancement, and MR imaging severity.

RESULTS

Hemorrhage was present in 20/31 patients (64.5%), with MHs on SWI in 18/31 (58.1%) at presentation and in 11/17 (64.7%) at follow-up. SAH was present in 3/31 on SWI and 4/31 on FLAIR, while 2/31 had IPH. At follow-up, no patients had acquired new MHs; 2/5 MHs in 1 patient resolved. Four patients with available SWI before PRES developed MHs after PRES onset. No association was found between the presence of MHs on SWI and DWI, SAH, IPH, enhancement, and MR imaging severity (all P > .05).

CONCLUSIONS

SWI showed a higher rate of MH than previously described, underscoring the potential of SWI in evaluating PRES. Such MHs typically persist and may develop after PRES onset. However, the clinical relevance of MHs in PRES is yet to be determined. We propose that MHs in PRES relate to endothelial cell dysfunction.

Medication neurotoxicity in children

Medication neurotoxicity may have a variety of imaging manifestations in children. In this pictorial essay, we review the two most common brain injury patterns, posterior reversible encephalopathy syndrome (PRES) and acute toxic leukoencephalopathy (ATL). Proposed etiologies, salient features on neurological imaging, and methods for differentiating these entities and their implications will be discussed. Certain agents do not fall into these two broad patterns but instead characteristically involve central structures. We individually review several medications and their respective neurotoxic appearances including methotrexate, cyclosporine A, tacrolimus, metronidazole and vigabatrin. Diagnosis of medication neurotoxicity may be achieved by the combination of new-onset neurological deficits, recent initiation of a new therapy agent and distinctive findings on magnetic resonance imaging. Clinical and radiological improvement and/or resolution are frequently observed after the agent is discontinued.

A case of posterior reversible encephalopathy syndrome after emergence from anesthesia

Posterior reversible encephalopathy syndrome (PRES) is a relatively new clinical entity characterized by reversible neurological symptoms with findings indicating leukoencephalopathy on imaging studies. Reports of PRES in the field of anesthesiology have been quite limited. A patient with therapeutic anticoagulant developed PRES immediately after emergence from anesthesia, in which her status was initially recognized as delayed recovery from anesthesia with transient hypertension because an emergent head computed tomography (CT) scan was almost normal. Subsequently, magnetic resonance imaging (MRI) was also performed according to a radiologist's recommendation because the CT results showed areas of slightly low attenuation in the frontoparieto-occipital lobes bilaterally, suggesting PRES; otherwise, ischemic events. MRI showed subcortical increased T(2) and fluid-attenuated inversion recovery (FLAIR) intensity in the occipitoparietal regions bilaterally with slight increase in the apparent diffusion coefficient signal on diffusion-weighted imaging, which confirmed a diagnosis of PRES. Gradually, the patient regained consciousness and became responsive with antihypertensive therapy. A prompt and accurate diagnosis of PRES is important to avoid irreversible brain damage, for example, intracranial hemorrhage, especially in a patient receiving anticoagulation therapy.

Tacrolimus related neurologic complication after pediatric kidney transplantation

Recently significant neurotoxicity has been reported with the use of carcineurin inhibitors. An 11-year-old-girl had undergone a transplantation of kidney from her mother. On post-operative day 12, hypertension, headache, and left motor weakness (grade I) suddenly occurred. The brain-magnetic resonance imaging and magnetic resonance angiography showed acute cerebral infarction at subcortical white matter of the right hemisphere and multiple stenoses of both anterior cerebral artery and middle cerebral artery. While stopping tacrolimus treatment, we experienced clinical and radiological improvement. So, the neurological complications of this patient seem to have been caused by the use of tacrolimus.

Linguistic history of posterior reversible encephalopathy syndrome: mirror of developing knowledge

BACKGROUND

the term posterior reversible encephalopathy syndrome (PRES) was first proposed in 2000. Since then, the acronym PRES has become very popular in imaging and clinical literature as it is short, easy to say and remember, and neatly couples the frequent localization of neuroimaging findings along with the typical outcome of this syndrome. Another possible reason for the popularity of this acronym in clinical circles is the connotation of PRES with (elevated blood) PRESsure, as a majority of cases are believed to be associated with hypertension. However, problems exist with the interpretation and common understanding of PRES, questioning the appropriateness of "P" and "R" in the acronym. The linguistic issues related to the acronym of PRES are interesting.

OBJECTIVES

the aim of this work is to analyze the controversies related to the acronym of PRES.

RESULTS

in 2006, modifying the meaning of the acronym was suggested, renaming it Potentially Reversible Encephalopathy Syndrome in order to adjust to the cases when posterior involvement is not prominent and emphasize that the reversibility is not spontaneous. This meant the creation of a backronym, where the new phrase is constructed by starting with an existing acronym.

CONCLUSION

this new backronym indicates that the original acronym of PRES has become a misnomer.

Unexpected seizure attack in a patient with spinal metastasis diagnosed as posterior reversible encephalopathy syndrome

Seizure is a foreseeable risk in patients with brain lesion. However, seizure during treating non-brain lesion is not a familiar situation to neurosurgeon. Posterior reversible encephalopathy syndrome (PRES) is a relatively common situation after systemic chemotherapy. The aim of this study is to make neurosurgeons aware of this potential medical problem. A 52-year-old woman with advanced gastric cancer, presented with low back pain due to spinal metastasis at the 4th lumbar vertebra. Ten cycles of chemotherapy with FOLFOX (5-Fluoruracil/Oxaliplatin) had been completed 23 days ago. Two days before the planned operation, a generalized tonic clonic seizure occurred. She did not have a history of hypertension or seizure. The seizure was stopped with lorazepam 4mg. The brain magnetic resonance (MR) imaging showed high signal changes in both parieto-occipital lobes on the T2-weighted images, and these were partially enhanced, suggesting PRES. The surgery was preceded by treatment with an antiepileptic drug. The MR images, taken 1.5 months after the seizure, showed that the lesion was no longer present. At 3 month follow-up, no additional seizure attack occurred without any seizure medication. The possibility of a seizure attack should be considered if the patient has a history of chemotherapy.

Analytic Review: Neurological Complications of Transplantation

Recipients of solid organ or hematopoietic cell transplants are at risk of life-threatening neurological disorders including encephalopathy, seizures, infections and tumors of the central nervous system, stroke, central pontine myelinolysis, and neuromuscular disorders—often requiring admission to, or occurring in, the intensive care unit (ICU). Many of these complications are linked directly or indirectly to immunosuppressive therapy. However, neurological disorders may also result from graft versus host disease, or be an expression of the underlying disease which prompted transplantation, as well as injury induced during radiation, chemotherapy, surgery, and ICU stay. In rare cases, neuroinfectious pathogens may be transmitted with the transplanted tissue or organ. Diagnosis may be a challenge because clinical symptoms and findings on neuroimaging lack specificity, and a biological specimen or tissue diagnosis is often needed for definitive diagnosis. Management is centered on preventing further neurological injury, etiology-targeted therapy, and balancing the benefits and toxicities of specific immunosuppressive agents.

Diffusion-weighted magnetic resonance imaging in acute reversible toxic leukoencephalopathy: A report of two cases

Acute toxic leukoencephalopathy may be caused by endogenous or exogenous toxins. It may reverse clinically if the offending agent is withdrawn or the underlying condition is treated. However, demonstration of reversibility on imaging, especially with diffusion-weighted MRI, has been reported only very recently. We report two such cases.

Childhood posterior reversible encephalopathy syndrome

Posterior Reversible Encephalopathy Syndrome (PRES) is a clinicoradiologic syndrome characterised clinically by headaches, altered consciousness, visual disturbances and seizures and radiological changes which can resolve. However left untreated it can be fatal and not all cases are reversible. It can occur in many settings, the most common being hypertensive crisis. We discuss the clinical and radiological features of this increasingly diagnosed condition among children and current thinking on its pathogenesis. A brief case is used to highlight the variable presentation of PRES. PRES is often unsuspected by the clinician and radiologists may be first to suggest the diagnosis. Accurate assessment including blood pressure measurement, appropriate imaging and rapid treatment is required to avoid a devastating outcome.

Posterior reversible encephalopathy syndrome after liver transplantation in children: a rare complication related to calcineurin inhibitor effects

PRES is a neuroclinical and radiological syndrome that results from treatment with calcineurin inhibitor immunosuppressives. Severe hypertension is commonly present, but some patients may be normotensive. We report herein two children who received liver transplants, as treatment for biliary atresia in the first case and for Alagille's syndrome in the second one. In the early postoperative, both patients presented hypertension and seizures. In both cases, the image findings suggested the diagnosis of PRES. The CT scan showed alterations in the posterior area of the brain, and brain MRI demonstrated parietal and occipital areas of high signal intensity. Both children were treated by switching the immunosuppressive regimen and controlling arterial blood pressure. They displayed full recuperation without any neurologic sequelae. Probably, the pathophysiology of PRES results from sparse sympathetic innervation of the vertebrobasilar circulation, which is responsible for supplying blood to the posterior areas of the brain. In conclusion, all liver-transplanted children who present with neurological symptoms PRES should be considered in the differential diagnosis, although this is a rare complication. As treatment, we recommend rigorous control of arterial blood pressure and switching the immunosuppressive regimen.

Seizures: emergency neuroimaging

The various findings observed on computed tomography (CT) and magnetic resonance (MR) imaging examinations in patients with seizures reflect the variety of different causes that give rise to this common neurologic symptom. In the emergency setting, CT is most valuable in its ability to accurately identify acute abnormalities that require emergent medical or surgical treatment. MR imaging, by contrast, is usually reserved for patients with recurrent or refractory seizures. The accurate interpretation of either modality requires familiarity with how seizures are classified clinically, the most common presenting features of different causes for seizures, the relevant neuroanatomy, and the imaging manifestations of both common and uncommon causes of seizures and epilepsy. Of particular practical importance to the radiologist is the ability to recognize (1) the most common findings in patients with recurrent seizures and (2) potentially reversible causes for seizures that require prompt intervention to avoid or minimize permanent brain injury. This article surveys a variety of different causes for seizures and epilepsy, focusing on specific clinical features that can help to refine differential diagnosis, and on imaging findings characteristic of different disorders.

Posterior reversible encephalopathy syndrome

Posterior reversible encephalopathy syndrome (PRES) is characterized by headache, altered mental status, visual disturbances, and seizures. Radiological features typically include edema of the posterior cerebral regions, especially of the parietooccipital lobes. Atypical imaging features, such as involvement of anterior cerebral regions, deep white matter, and the brain stem are also frequently seen. Vasoconstriction is common in vascular imaging. Different conditions have been associated with PRES, but toxemia of pregnancy, solid organ or bone marrow transplantation, immunosuppressive treatment, cancer chemotherapy, autoimmune diseases, and hypertension are most commonly described. The pathophysiology of PRES is unclear and different hypotheses are being discussed. Posterior reversible encephalopathy syndrome is best managed by monitoring and treatment in the setting of a neurointensive care unit. The prognosis is usually benign with complete reversal of clinical symptoms within several days, when adequate treatment is immediately initiated. Treatment of severe hypertension, seizures, and withdrawal of causative agents represent the hallmarks of specific therapy in PRES. Delay in diagnosis and treatment may lead to permanent neurological sequelae. Therefore, awareness of PRES is of crucial importance for the intensivist.

Posterior Reversible Encephalopathy Syndrome and Anti-Angiogenic Agents: A Case Report

Posterior reversible encephalopathy syndrome is an increasingly recognised clinico-radiological entity, associated with several medical conditions (such as systemic arterial hypertension) and characterised by seizures, altered mental status, headaches, and visual symptoms. Magnetic resonance imaging is a key component in this diagnosis, with hyperintense foci in T₂-weighted images, corresponding to vasogenic oedema. The pathophysiology is not fully understood but probably involves loss of auto-regulation of cerebral vasculature or endothelial dysfunction or both. A 56-year-old male, suffering from a gastro-intestinal stromal tumour with hepatic metastasis resistant to imatinib, on therapy with sunitinib, came to the Emergency Department because of headaches, hallucinations, and loss of vision. There was no previous history of high blood pressure. A hypertensive crisis was diagnosed; ophthalmological examination on admission showed no light perception bilaterally. Brain imaging displayed bilateral parieto-occipital and frontal vasogenic oedema, consistent with the clinical diagnosis of posterior reversible encephalopathy syndrome. After treatment of hypertension and suspension of sunitinib, the patient recovered from his symptoms. Control imaging showed no oedema. Angiogenesis inhibitors, such as sunitinib and bevacizumab, can cause hypertension, one of the many medical conditions associated with the posterior reversible encephalopathy syndrome. This syndrome should be considered in cases of acute visual loss, particularly in view of its reversible nature when diagnosed and treated promptly.

Neuroimaging findings in alcohol-related encephalopathies

OBJECTIVE

Our aim was to review the emergent neuroimaging findings of alcohol-related CNS nontraumatic disorders. Alcohol (ethanol) promotes inflammatory processes, increases DNA damage, and creates oxidative stress. In addition, the accompanying thiamine deficiency may lead to Wernicke encephalopathy. Associated changes in serum osmolarity may lead to acute demyelination.

CONCLUSION

Alcohol-related encephalopathies can be life-threatening conditions but can be prevented or treated, if recognized.

Posterior reversible encephalopathy syndrome and venous thrombosis

Posterior reversible encephalopathy syndrome (PRES) and venous thrombosis are frequently encountered first in the emergency setting and share some common characteristics. The clinical presentation in both entities is vague, and the brain parenchymal findings of PRES syndrome may resemble those of venous thrombosis in some ways. Both entities often occur in a bilateral posterior distribution and may be associated with reversible parenchymal findings if the inciting factor is treated. These diagnoses should be at the forefront of the differential diagnosis when confronted with otherwise unexplained brain edema, among other findings described in this article.

Involvement of the cervical cord and medulla in posterior reversible encephalopathy syndrome

The posterior reversible encephalopathy syndrome (PRES) is characterized by patchy cortical and subcortical lesions in the distribution of the posterior circulation. The lesions are classically reversible. This syndrome has multiple etiologies, most of which cause acute hypertension. We present a case of PRES with involvement of the medulla and cervical cord (apart from the typical parieto-occipital lesions)--an extremely rare imaging manifestation of PRES. It is important to recognize the imaging findings of PRES in spinal cord, and avoid misdiagnosis as myelitis by proper clinical correlation. Typically patients with myelitis have a profound neurodeficit, while patients with spinal manifestations of PRES are asymptomatic. Involvement of the cord in PRES has probably been an underrecognized entity as spinal imaging is not routinely performed in posterior reversible encephalopathy syndrome.

Polyarteritis nodosa associated with essential mixed cryglobulinemia revealed by subarachnoid hemorrhage

Polyarteritis nodosa (PAN) is a systemic necrotizing vasculitis mediated by intravascular deposition of immune complexes. We report a 55-year-old man with PAN revealed by CNS vasculitis with subarachnoid hemorrhage and brainstem vasogenic oedema, associated with essential mixed cryoglobulinemia. In spite of aggressive treatment (steroids and cyclophosphamide), the patient became tetraplegic. A pathophysiological relationship between cryoglobulin and PAN can be suspected. Mixed cryoglobulinemia may trigger vasculitis with PAN features, possibly explaining the lack of treatment response.

Reversibility of cytotoxic edema in tacrolimus leukoencephalopathy

Posterior reversible encephalopathy syndrome, a serious neurotoxicity, may develop rarely in patients receiving tacrolimus. Because the underlying etiology of posterior reversible encephalopathy syndrome is vasogenic edema, it is generally accepted to be a reversible neurologic condition. Cranial magnetic resonance imaging techniques enable detection of the type of edema, and they are widely used in the differential diagnosis and prognostic prediction of posterior reversible encephalopathy syndrome. Presented here is a case of posterior reversible encephalopathy syndrome in which the patient recovered completely, despite radiologic findings indicating the coexistence of vasogenic and cytotoxic edema secondary to tacrolimus therapy after liver transplantation.

Posterior reversible encephalopathy syndrome during posterior fossa tumor resection in a child

Posterior reversible encephalopathy syndrome (PRES) has been described in the setting of malignant hypertension, renal disease, eclampsia, and immunosuppression. In addition, a single case of intraoperative (posterior fossa craniotomy) PRES has been reported; however, this case occurred in an adult. The authors present a clinically and radiographically documented case of intraoperative PRES complicating the resection of a posterior fossa tumor in a 6-year-old child. During tumor resection, untoward force was used to circumferentially dissect the tumor, and excessive manipulation of the brainstem led to severe hypertension for a 10-minute period. An immediate postoperative MR image was obtained to rule out residual tumor, but instead the image showed findings consistent with PRES. Moreover, the patient's postoperative clinical findings were consistent with PRES. Aggressive postoperative management of blood pressure and the institution of anticonvulsant therapy were undertaken. The patient made a good recovery; however, he required a temporary tracheostomy and tube feedings for prolonged lower cranial nerve dysfunction. Posterior reversible encephalopathy syndrome can occur as a result of severe hypertension during surgery, even among young children. With prompt treatment, the patient in the featured case experienced significant clinical and radiographic recovery.

Pediatric central nervous system emergencies

This article summarizes current state-of-the-art techniques used in the management of pediatric neurologic emergencies. Solutions to challenges faced by the radiologist, including the selection of an appropriate modality for an individual patient, are discussed. Imaging appearances of specific entities are described with an emphasis on conditions unique to the pediatric population.

Posterior reversible encephalopathy syndrome as a complication of Guillain-Barré syndrome

Posterior reversible encephalopathy syndrome (PRES) is characterised by sudden hypertension that is associated with headache, seizure, visual disturbance and altered mental function. We report a 62-year-old woman with a sudden onset of complete bilateral visual loss, an admission blood pressure (BP) of 204/113mmHg, and flaccid weakness in all four limbs. The patient's cerebrospinal fluid and nerve conduction studies were consistent with a diagnosis of Guillain-Barré syndrome (GBS) and her brain MRI showed classic features of PRES. Her blood pressure was managed appropriately and her GBS was treated with plasmapheresis. Two months following presentation, the patient's vision recovered completely and she regained full power of her four limbs. She did not need any continuing antihypertensive medication. This report is the 8th of accumulating evidence that links PRES with GBS, and it shows that PRES can be the presenting feature following GBS treatment with intravenous (IV) immunoglobulins or later in recovery. Dysautonomia resulting from GBS is the most likely explanation of this strong association. GBS is mostly reversible when managed correctly; however, the literature suggests that failure to recognize or delay treatment can lead to cerebral infarction or even death.

Isolated acute nontraumatic cortical subarachnoid hemorrhage

Our aim was to review the etiologic background of isolated acute nontraumatic cSAH. While SAH located in the basal cisterns originates from a ruptured aneurysm in approximately 85% of cases, a broad spectrum of vascular and even nonvascular pathologies can cause acute nontraumatic SAH along the convexity. Arteriovenous malformations or fistulas, cortical venous and/or dural sinus thrombosis, and distal and proximal arteriopathies (RCVS, vasculitides, mycotic aneurysms, Moyamoya, or severe atherosclerotic carotid disease) should be sought by noninvasive imaging methods or/and conventional angiography. Additionally, PRES may also be a source of acute cSAH. In elderly patients, cSAH might be attributed to CAA if numerous hemorrhages are demonstrated by GRE T2 images. Finally, cSAH is rarely observed in nonvascular disorders, such as abscess and primitive or secondary brain tumors.

Posterior reversible encephalopathy syndrome and cerebral vasculopathy associated with influenza A infection: report of a case and review of the literature

BACKGROUND AND PURPOSE

Influenza A infection can precipitate encephalopathy, encephalitis, or Reye syndrome with the development of cerebral edema in children and is associated with an increased incidence of stroke in adults. The mechanism of these events is poorly understood. Posterior reversible encephalopathy syndrome (PRES) is seen in association with infection/sepsis, and cerebral vasculopathy has been demonstrated in PRES. We describe a case of PRES that develops in association with influenza A.

SUMMARY OF CASE

A normotensive 65-year-old woman presented with altered mentation and nausea in the setting of a viral prodromal illness ultimately confirmed as influenza A. Posterior reversible encephalopathy syndrome developed on the second day after admission. Catheter cerebral angiogram documented vasculopathy in PRES-involved regions with areas of focal vessel dilatation and string-of-bead appearance.

CONCLUSIONS

The association between influenza A and PRES with documentation of cerebral vasculopathy suggests a common systemic vascular mechanism behind PRES and influenza-related encephalopathic edema and stroke.