Posterior reversible encephalopathy syndrome, part 1: fundamental imaging and clinical features

Neurocognitive-neurological complications of liver transplantation: a review

Neurological complications are common after liver transplantation (LT) and they are associated with a significant morbidity. Long-term effects of LT on cognitive and psychological outcomes are not clear. The objective of this study was to summarize the present knowledge on the neurological and cognitive complications of LT, resulting from a systematic review of the literature in the last 10 years. Several studies have investigated the incidence and the pathophysiology of neurological complications; in contrast, the knowledge of cognitive and psychological status after LT is poor. Currently, the effect of LT on mental performance is debated. Some studies have shown an improvement of cognitive function after OLTX and, at the same time, a persistence of different cognitive deficits. In addition, the quality of life (QoL) and the psychological status after LT seem to improve but LT recipients have significant deficiencies in most QoL domains. Consequently, future studies are necessary in order to investigate cognitive alterations and QoL in LT recipients.

Vasculitis-like Syndromes

Vasculitis often presents a diagnostic challenge as the disease processes may have varied presentations. This article reviews some vasculitis-like "mimics," particularly emphasizing viral and bacterial infections, drug-related disorders, various malignancies, and other autoimmune disorders, all of which may have a similar clinical presentation. This article also highlights recent advances and the importance of accurate diagnosis and therapy.

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.

Brain death in a septic patient: possible relationship with posterior reversible encephalopathy syndrome?

A 41-year-old man with a previous kidney transplant was referred for arterial hypertension and acute renal failure. Initial neurological examination was normal. Laboratory data showed a high serum cyclosporine A concentration. A few hours later, he developed generalised tonic-clonic seizures. The brain computed tomogram was not remarkable, but Glasgow Coma Scale score remained at 8. Mechanical ventilation was required for rapidly progressive hypoxaemia related to Staphylococcus aureus pneumonia and septicaemia. Noradrenaline infusion was needed for only nine hours, with no major drop in mean arterial blood pressure. On day three his Glasgow Coma Scale score was 3/15, with fixed dilated pupils. The brain computed tomogram revealed bilateral hypodense lesions in the posterior areas together with cerebral oedema and the patient was subsequently declared brain dead. We discuss the possibility of a posterior reversible encephalopathy syndrome, likely triggered by a gram-positive septicaemia in addition to other risk factors.

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.

Posterior Reversible Encephalopathy Syndrome Secondary to Essential Hypertension

We present the case of a young man who was previously well, but became unconscious while watching a football match. He was initially found to be hypertensive, with clinical and echocardiographic evidence of cardiac failure. He also had a fixed and dilated pupil. CT brain scanning was normal and it was only after a MR brain scan was performed that the diagnosis of posterior reversible encephalopathy syndrome was raised. Despite the name of the condition implying that neurological deficits are reversible, this patient had a prolonged period of disability requiring long-term rehabilitation.

Influenza A encephalopathy, cerebral vasculopathy, and posterior reversible encephalopathy syndrome: combined occurrence in a 3-year-old child

Encephalopathy is an uncommon complication of childhood influenza infection, typically recognized during influenza epidemics. Imaging hallmarks include characteristic thalamic lesions, thalamic necrosis and hemispheric edema. We describe a child with acute influenza A associated necrotizing encephalopathy with MR angiographic evidence of significant cerebral vasculopathy and a hemispheric edema pattern consistent with PRES. This case reinforces that significant cerebral vasculopathy can accompany influenza infection and that influenza is a likely trigger for PRES.

[Reversible cerebral vasoconstriction syndrome]

Reversible cerebral vasoconstriction syndrome (RCVS) is more frequent than previously thought and is probably underdiagnosed. The mean age of onset is 42 years, and it affects slightly more women than men. RCVS is attributed to a transient, reversible dysregulation of cerebral vascular tone, which leads to multifocal arterial constriction and dilation. More than half the cases (60%) are secondary to exposure to vasoactive substances (e.g., cannabis, antidepressants, and nasal decongestants) or occur in the postpartum period. RCVS has a characteristic clinical and radiological course, developing in a single phase after a sudden onset, and there is generally no new event after 1 month. The main pattern of presentation begins with recurrent thunderclap headaches, often triggered by sexual activity or various Valsalva's maneuvers, over a period of 1 to 3 weeks. Seizures and focal neurological deficits are less frequent and generally start after the headaches. Cortical subarachnoid hemorrhage (22%), intracerebral hemorrhage (6%), seizures (3%), and reversible posterior leukoencephalopathy (9%) are early complications, occurring mainly within the first week. Ischemic events, including TIAs (16%) and cerebral infarction (4%), occur significantly later than hemorrhagic strokes, mainly during the second week. Diagnosis requires the demonstration of the characteristic "string and beads" on cerebral angiography and can be difficult, for 21% of patients have a normal initial magnetic resonance angiography (MRA) and 9% both a normal MRA and a normal transcranial Doppler. In these cases, the initial investigations must be repeated after a few days. The final diagnosis is made when a follow-up MRA shows resolution or at least marked improvement of the arterial abnormalities within 12 weeks. RCVS is sometimes associated with other large artery lesions of the head and neck, including dissections and unruptured aneurysms, especially during the postpartum period. Nimodipine is the treatment most often recommended. In our experience, it is not especially effective in severe RCVS. Relapses are possible but rare and have not yet been reported in prospective series. Although the exact pathophysiology remains speculative, strong recommendations against vasoactive substances appear prudent.

Posterior reversible encephalopathy syndrome in an 87-year-old woman with Escherichia coli bloodstream infection

We present the case of an 87-year-old woman with history of hypertension, hypercholesterolemia, ischemic heart diseases, urinary tract infections, and cerebrovascular disease who experienced a transient clinical picture characterized by confusion, lethargy, and acute renal dysfunction in the course of urinary tract infection with Escherichia coli bacteremia. Escherichia coli bloodstream infection was associated with brain computed tomography (CT) and magnetic resonance imaging (MRI) patterns in which the lesion distribution was consistent with posterior reversible encephalopathy syndrome (PRES). Diagnosis of PRES was confirmed by demonstration of vasogenic edema on apparent diffusion coefficient (ADC) maps and near-complete resolution of clinical manifestations at discharge.

[Reversible cerebral vasoconstriction syndrome]

Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by severe headaches, as well as vasoconstriction of cerebral arteries, which resolves spontaneously in one to three months. This condition has a moderate female preponderance. The mean age of onset is around 45 years. About 60% of the cases are secondary, mainly occurring during postpartum and/or after exposure to vasoactive substances. The main clinical presentation includes multiple recurrent thunderclap headaches over one to three weeks. The major complications of RCVS are localized cortical subarachnoid hemorrhages (cSAH) (20-25%) and parenchymal strokes (5-10%). Complications occur with different time courses: hemorrhages (cSAH and intracerebral hemorrhages), and posterior reversible encephalopathy syndrome are early events occurring during the first week, while ischemic events including TIAs and cerebral infarcts occur significantly later, during the second week. Diagnosis requires the demonstration of the "string and beads" aspect of cerebral arteries by a cerebral angiogram (MRA, CTA or conventional) and the demonstration of the complete or marked normalisation of arteries by a repeat angiogram performed within 12 weeks of onset. Treatment is based on nimodipine that seems to reduce thunderclap headaches within 48h. However, nimodipine has not proven any efficacy against the hemorrhagic and ischemic complications of RCVS. Relapses are possible but rare and have not been reported yet in prospective series. It seems appropriate to advise the patients to avoid sympathomimetic and serotoninergic substances.

Late Onset Postpartum Eclampsia: It is Really Never Too Late-A Case of Eclampsia 8 Weeks after Delivery

Introduction. Eclampsia is the combination of preeclampsia and seizures. Approximately one-half of all cases of eclampsia occur postpartum. Thereby late onset postpartum eclampsia is defined by its onset more than 48 hours after delivery. Summary of Case. We report a postpartum eclampsia occurring 8 weeks after delivery, which is the latest onset ever described. The course was complicated by an intracerebral hemorrhage (ICH). Conclusion. A late onset postpartum eclampsia even several weeks after delivery should be considered as possible diagnosis, since early treatment initiation with magnesium sulphate and antihypertensive medication prevents severe complications and reduces mortality.

Mesial temporal sclerosis after posterior reversible encephalopathy syndrome

Neither intrathecal methotrexate nor posterior reversible encephalopathy syndrome has previously been reported to result in mesial temporal sclerosis. Described here is the case of a boy with no risk factors for mesial temporal sclerosis who presented with posterior reversible encephalopathy syndrome and partial complex seizures 8 days after initiation of intrathecal methotrexate for treatment of Burkitt lymphoma, and who ultimately progressed to intractable temporal lobe epilepsy due to left mesial temporal sclerosis.

Arterial spin-labeled MR perfusion imaging: clinical applications

Arterial spin labeling (ASL) imaging soon will be available as a routine clinical perfusion imaging sequence for a significant number of MR imaging scanners. The ASL perfusion technique offers information similar to that provided by conventional dynamic susceptibility sequences, but it does not require the use of an intravenous contrast agent, and the data can be quantified. The appearance of pathology is affected significantly by the ASL techniques used. Familiarity with the available sequence parameter options and the common appearances of pathology facilitates perfusion interpretation.

Hemorrhage in posterior reversible encephalopathy syndrome: imaging and clinical features

BACKGROUND AND PURPOSE

Hemorrhage is known to occur in posterior reversible encephalopathy syndrome (PRES), but the characteristics have not been analyzed in detail. The purpose of this study was to evaluate the imaging and clinical features of hemorrhage in PRES.

MATERIALS AND METHODS

Retrospective assessment of 151 patients with PRES was performed, and 23 patients were identified who had intracranial hemorrhage at toxicity. Hemorrhage types were identified and tabulated, including minute focal hemorrhages (<5 mm), sulcal subarachnoid hemorrhage, and focal hematoma. Clinical features of hemorrhage and nonhemorrhage PRES groups were evaluated, including toxicity blood pressure, coagulation profile/platelet counts, coagulation-altering medication, and clinical conditions associated with PRES. Toxicity mean arterial pressure (MAP) groups were defined as normal (<106 mm Hg), mildly hypertensive (106-116 mm Hg), or severely hypertensive (>116 mm Hg).

RESULTS

The overall incidence of hemorrhage was 15.2%, with borderline statistical significance noted between the observed clinical associations (P = .07). Hemorrhage was significantly more common (P = .02) after allogeneic bone marrow transplantation (allo-BMT) than after solid-organ transplantation. The 3 hemorrhage types were noted with equal frequency. A single hemorrhage type was found in 16 patients, with multiple types noted in 7. Patients undergoing therapeutic anticoagulation were statistically more likely to develop hemorrhage (P = .04). No difference in hemorrhage incidence was found among the 3 blood pressure subgroups (range, 14.9%-15.9%).

CONCLUSIONS

Three distinct types of hemorrhage (minute hemorrhage, sulcal subarachnoid hemorrhage, hematoma) were identified in PRES with equal frequency. The greatest hemorrhage frequency was seen after allo-BMT and in patients undergoing therapeutic anticoagulation. Hemorrhage rate was independent of the toxicity blood pressure.

Posterior reversible encephalopathy syndrome associated with methotrexate neurotoxicity: conventional magnetic resonance and diffusion-weighted imaging findings

The addition of intrathecal methotrexate to treatment protocols has increased survival rates in children with acute lymphoblastic leukemia but is also associated with varying degrees of neurotoxicity. We describe a 15-year-old female patient diagnosed with acute lymphoblastic leukemia presenting with status epilepticus after receiving intrathecal methotrexate. Magnetic resonance imaging showed reversible cortical and subcortical changes consisting of high-intensity lesions on T2-weighted and fluid-attenuated inversion recovery sequences with postgadolinium enhancement, low signal intensity on diffusion-weighted imaging and increased apparent diffusion coefficient. These findings were consistent with the posterior reversible encephalopathy syndrome. We report our conventional magnetic resonance and diffusion-weighted imaging findings and briefly discuss the pathophysiology of the syndrome.

Chemotherapy-related posterior reversible leukoencephalopathy syndrome

BACKGROUND

A 45-year-old woman with small-cell lung cancer presented to a hospital emergency department in an acute confusional state, with blurred vision and mild headache. Following progressively increasing lethargy, she subsequently became unresponsive to tactile and verbal stimuli. She had recently been started on chemotherapy with carboplatin and gemcitabine.

INVESTIGATIONS

Physical examination, imaging studies including brain MRI, noncontrast brain CT scans and magnetic resonance angiography, continuous EEG monitoring, and cerebrospinal fluid analysis.

DIAGNOSIS

Posterior reversible leukoencephalopathy syndrome (PRES) related to chemotherapy, and nonconvulsive status epilepticus related to PRES.

MANAGEMENT

Withholding of chemotherapeutic agents, and antiseizure therapy for the status epilepticus.

The cat with neurological manifestations of systemic disease. Key conditions impacting on the CNS

PRACTICAL RELEVANCE

A number of systemic diseases are associated with neurological deficits. Most systemic diseases that impact on the nervous system result in multifocal neurological signs; however, isolated deficits can also be observed. This article reviews the clinical signs, pathophysiology, diagnosis, treatment and prognosis of four important systemic diseases with neurological consequences: feline infectious peritonitis, toxoplasmosis, hypertension and hepatic encephalopathy.

CLINICAL CHALLENGES

Early recognition of systemic signs of illness in conjunction with neurological deficits will allow for prompt diagnosis and treatment. While neurological examination of the feline patient can undoubtedly be challenging, hopefully the accompanying articles in this special issue will enable the clinician to approach these cases with more confidence.

EVIDENCE BASE

The veterinary literature contains numerous reports detailing the impact of systemic disease on the nervous system. Unfortunately, very few references provide detailed descriptions of large cohorts of affected cats. This review summarises the literature underpinning the four key diseases under discussion.

MR imaging findings of medulla oblongata involvement in posterior reversible encephalopathy syndrome secondary to hypertension

Although the combination of MR imaging findings and clinical evidence of hypertension may suggest the diagnosis of posterior reversible encephalopathy syndrome (PRES), MR imaging findings with only involvement of the medulla oblongata pose a diagnostic dilemma. In the cases presented here, we demonstrated MR imaging findings of a presumed brain stem (medulla oblongata) variant of PRES and emphasized the diagnostic value of diffusion-weighted imaging (DWI).

Atypical imaging findings in a renal transplant patient with reversible posterior leukoencephalopathy syndrome: a case report

Background

Atypical clinical and imaging findings in Reversible Posterior Leukoencephalopathy Syndrome are recognized with increasing frequency.

Case report

We report a case of an adult in his 5^th decade immunosupressed with methilprednisolone, tacrolimus and micophenolate who two months after renal transplantation, multiple infections and an episode of humoral rejection became hypertensive with severe headaches, visual field abnormalities, seizures, left hemiparesis and hemineglect.

Computed Tomography scan of the brain showed a hypo dense lesion in the left occipital lobe. Ischemic stroke was diagnosed and aspirin and permissive hypertension were indicated. Twelve hours later he developed left sided motor seizures and cortical blindness. Magnetic Resonance Image showed hyper intensity in T2 and FLAIR in both occipital lobes and a small area of cortical restricted diffusion in Diffuson Weighted Images in the left occipital lobe. With a diagnosis of Reversible Posterior Leukoencephalopathy Syndrome his blood pressure was controlled with intravenous labetalol, and two days later the neurologic findings returned to baseline and most Computed tomography findings resolved.

Conclusion

This case underscores that in the appropriate setting Reversible Posterior Leukoencephalopathy Syndrome should be suspected and the clinician should not be misled by atypical clinical or imaging findings. In contrast to other pathologies that resemble Reversible Posterior Leukoencephalopathy Syndrome, with the right and timely treatment, signs, symptoms and images can be completely reversible.

Reversible encephalopathy after cardiac transplantation: histologic evidence of endothelial activation, T-cell specific trafficking, and vascular endothelial growth factor expression

Reversible encephalopathy after transplantation is well recognized. The condition is commonly thought to be related to immune suppression, and a characteristic brain imaging pattern is typically recognized with vasogenic edema in the parietal and occipital regions, typically termed posterior reversible encephalopathy syndrome (PRES). We report the case of a patient with reversible encephalopathy after cardiac transplantation with brain biopsy evidence of endothelial activation, selective intravascular/perivascular T-cell trafficking, and VEGF expression in astrocytes, neurons, and the endothelium.

Posterior reversible encephalopathy syndrome

PURPOSE OF REVIEW

The ophthalmologist may be called upon to evaluate visual loss in a patient with posterior reversible encephalopathy syndrome. Familiarity with presentation and clinical management is imperative, as visual loss is often reversible with prompt treatment directed at causative factors.

RECENT FINDINGS

Since its initial description in 1996, the predisposing factors, clinical presentation and radiographic variation of posterior reversible encephalopathy syndrome continue to expand. Case reports of newly uncovered associations of the syndrome appear frequently. Originally considered a subcortical disease of the posterior cerebrum, posterior reversible encephalopathy syndrome has been shown to affect gray matter and can involve both the anterior and posterior cortex, brainstem, cerebellum or even the spinal cord. The pathophysiologic basis of cerebral edema and molecular mechanisms of edema underlying the syndrome are currently being revealed.

SUMMARY

Acute hypertension, eclampsia, immunosuppressive medication, infection or autoimmune diseases can all result in the clinical syndrome of vasogenic edema in the central nervous system leading to headache, seizure, confusion and frequent visual loss. The biologic basis for the syndrome is likely an insult to cerebral vascular autoregulation. MRI is essential in diagnosing a cerebral cause for visual loss. The ophthalmologist may have the initial opportunity to diagnose the syndrome. Treatment may reverse clinical deficits, and is based on eliminating the etiologic causation.

Encephalopathy syndrome in children with hemato-oncological disorders is not always posterior and reversible

BACKGROUND

Posterior reversible leukoencephalopathy (PRES) is a clinical-radiological event that can affect children undergoing chemotherapy regimen. Studies have shown that it is not always reversible, in spite of its original definition. We analyzed PRES cases which occurred during the last 10 years at our institute to focus on their clinical, radiological and EEG follow-up.

PROCEDURES

We analyzed 12 cases of PRES in children who underwent intensive chemotherapy regimens, detailing the acute neurological presentation of the syndrome, their neuro-imaging characteristics (MRI) and EEG findings, in both an acute phase and during follow-up.

RESULTS

All patients survived the acute event, showing a clinical recovery of the acute neurological signs in 1-3 days and normalization of the EEG pattern in a period ranging from 1 to 8 months. During long term follow-up, four patients developed either clinical impairment or EEG-MRI anomalies.

CONCLUSIONS

We suggest that a long term follow-up is necessary to determine the reversibility of the neurological events. Clinical observation, as well as EEG and MRI should be included in follow-up evaluations.

Posterior reversible encephalopathy syndrome, part 2: controversies surrounding pathophysiology of vasogenic edema

Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic state accompanied by a unique brain imaging pattern typically associated with a number of complex clinical conditions including: preeclampsia/eclampsia, allogeneic bone marrow transplantation, solid organ transplantation, autoimmune diseases and high dose cancer chemotherapy. The mechanism behind the developing vasogenic edema and CT or MR imaging appearance of PRES is not known. Two theories have historically been proposed: 1) Severe hypertension leads to failed auto-regulation, subsequent hyperperfusion, with endothelial injury/vasogenic edema and; 2) vasoconstriction and hypoperfusion leads to brain ischemia and subsequent vasogenic edema. The strengths/weaknesses of these hypotheses are reviewed in a translational fashion including supporting evidence and current available imaging/clinical data related to the conditions that develop PRES. While the hypertension/hyperperfusion theory has been most popular, the conditions associated with PRES have a similar immune challenge present and develop a similar state of T-cell/endothelial cell activation that may be the basis of leukocyte trafficking and systemic/cerebral vasoconstriction. These systemic features along with current vascular and perfusion imaging features in PRES appear to render strong support for the older theory of vasoconstriction coupled with hypoperfusion as the mechanism.