Clinicoradiological spectrum of reversible splenial lesion syndrome (RESLES) in adults: a retrospective study of a rare entity

Altitude-related features and prognosis in patients with reversible splenial lesion syndrome

INTRODUCTION

RESLES (Reversible splenial lesion syndrome) can be observed secondary to various diseases, and intramyelinic edema may play a crucial role in the pathogenesis of SCC (Splenium of the corpus callosum). Some studies have suggested that hypoxic-ischaemic encephalopathy may constitute a risk factor for SCC lesions. However, the potential impact of high-altitude environments on SCC, especially during chronic exposure, remain obscure.

METHODS

Our study included 19 patients who satisfied the diagnostic criteria of RESLES at high altitudes. Ten low-altitude patients with RESLES were included as controls. All participants received MRI (Magnetic resonance imaging) scans twice. Routine blood tests, liver, kidney and thyroid function, coagulation function, electrolytes and vitamins were detected during hospitalization and before discharge. In addition, the patients were followed up in May 2023.

RESULTS

Hypoxic environments at high altitudes may increase the risk of RESLES. The two groups showed different clinical symptoms. High-altitude patients had significantly higher CRP levels than low-altitude patients. The lesion size in high-altitude patients showed a positive correlation with SaO2 levels. However, the patients at low altitudes had positive correlation trends between lesion size and several inflammatory markers (WBC, NEU and CRP). All patients had a benign prognosis that may not be affected by the use of prednisone acetate.

CONCLUSIONS

Hypoxic environments at high altitudes may play a role in the aetiology of RESLES. Additionally, RESLES is a reversible disease and the administration of glucocorticoids may be dispensable for its treatment.

Mild Encephalopathy/Encephalitis With Reversible Splenial Lesion Associated With Meningitis Related to Mumps Disease: An Unusual Presentation in a Male Adult

Mild encephalitis/encephalopathy with reversible splenial lesion (MERS) is characterized by mild neurological manifestations associated with spontaneously reversible lesions of the splenium of the corpus callosum. While various conditions and diseases can trigger MERS, infectious causes predominate, with mumps being notably linked to MERS in the pediatric population. Although rare in adults, there are sporadic case reports associating mumps with MERS. Here we report a 23-year-old male patient with a typical presentation of mumps who presented with meningeal syndrome, dizziness, seizures, and right orchitis. Brain MRI showed classic findings of MERS syndrome while cerebrospinal fluid analysis demonstrated lymphocytic pleocytosis. Our patient had a confirmed diagnosis of mumps disease with multiple complications, including MERS, meningitis, and orchitis, and was managed with symptomatic medications and antiviral therapy. Subsequently, there was a gradual resolution of these manifestations and the outcome was favorable, with no residual sequelae.

Case report: Clinically mild encephalitis/encephalopathy with a reversible splenial lesion: an autopsy case

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion is a clinicoradiological syndrome characterized by transient neuropsychiatric symptoms and hyperintensity of the splenium of the corpus callosum on diffusion-weighted MRI. Although intramyelinic edema and inflammatory cell infiltration can be predicted by MRI, the pathology of the splenium of the corpus callosum remains unknown. We encountered a case of clinically mild encephalitis/encephalopathy with a reversible splenial lesion and hypoglycemia in a patient who died of sepsis, and an autopsy was performed. The postmortem pathological findings included intramyelinic edema, myelin pallor, loss of fibrous astrocytes, microglial reactions, and minimal lymphocytic infiltration in the parenchyma. Based on these findings, transient demyelination following cytotoxic edema in the splenium of corpus callosum was strongly considered a pathogenesis of "clinically mild encephalitis/encephalopathy with a reversible splenial lesion" associated with hypoglycemia, and it could be generalized for the disease associated with the other causes. As cytotoxic edema could be the central pathology of the disease, the recently proposed term cytotoxic lesions of the corpus callosum may be applicable to this syndrome.

Hemorrhagic fever with renal syndrome and reversible splenial lesion syndrome

Hemorrhagic fever with renal syndrome (HFRS) and reversible splenial lesion syndrome are both considered uncommon conditions relatively rare. Fever, hemorrhage, and acute kidney injury are the prevailing symptoms frequently observed in cases of HFRS. We describe a case of a middle-aged man who had been hospitalized with fever and acute neurological symptoms. His main symptom was recurrent dizziness. Cranial computed tomography (CT) did not reveal any obvious lesions, such as encephalorrhagia or infarctions. The splenium of corpus callosum showed hyperintensity on brain magnetic resonance imaging (MRI), which is in line with the characteristic radiographic observations of reversible splenial lesion syndrome (RESLES). Further analyses revealed that the patient's platelet counts had decreased to 7×109/L while hemorrhagic fever antibodies were positive. Eventually, the patient was diagnosed with HFRS and exhibited clinical improvements after active treatment.

Reversible splenial lesion after surgery for distant arteriovenous malformation: a case report

Isolated lesions of the corpus callosum are rare and may represent permanent but also transient responses to various pathology termed "reversible splenial lesion syndrome" (RESLES) when in light of relevant clinical presentation. We present the first case of the RESLES after elective surgery for distant arteriovenous malformation (AVM), followed by a slight speech disturbance and MRI verified small, oval, well-circumscribed area of apparent cytotoxic edema in the center of the corpus callosum splenium, which completely resolved within 15 days. Surgery for AVM is followed by the complex adaptation to a new vascular pattern, RESLES might develop, and should be suspected.

An elderly man with mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) without neuropsychiatric sequelae

Mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is less common in the elderly, and most have some sequelae. However, even in the elderly, MERS may have a good prognosis, and a specific treatment is not always required.

Mild Encephalitis/Encephalopathy with a Reversible Lesion in The Splenium

Mild encephalitis/encephalopathy with a reversible lesion in the splenium (MERS) is a clinico-radiological syndrome with mild central nervous system symptoms and a reversible lesion in the splenium of the corpus callosum. It is mainly associated with a number of viral and bacterial infections, including Coronavirus disease 2019 (COVID-19). In this paper, we report four MERS patients. One had a mumps infection, the second had aseptic meningitis, the third had Marchiafava-Bignami disease, and the fourth had atypical pneumonia associated with COVID-19 infection.

Comparison of the Diagnostic Accuracy of Percutaneous Fistula Contrast-Enhanced Ultrasound Combined with Transrectal 360° 3-D Imaging and Conventional Transrectal Ultrasound in Complex Anal Fistula

This study compared the diagnostic accuracy of percutaneous fistula contrast-enhanced ultrasound (CEUS) combined with 360° 3-D transrectal ultrasound (TRUS) imaging (CEUS + 360°-TRUS) with that of conventional transrectal ultrasound in the diagnosis of complex anal fistulas. A total of 156 patients clinically diagnosed with complex anal fistula from January 2020 to December 2021 were studied and randomly divided into an experimental group (n = 82) and a control group (n = 74). Patients in the experimental group were examined by percutaneous fistula CEUS combined with CEUS + 360°-TRUS, while patients in the control group were examined using TRUS. The detection of fistulas (main tract, branch and internal orifice) and the accuracy of Parks classification were compared between the two groups. Recurrences were followed up at 1, 3 and 6 mo after the surgery. A total of 156 patients were included, aged 23-68 y (average: 37.7 ± 18.2 y). In both groups, the course of disease was <1 mo in 128 cases, 1-2 mo in 22 cases and >3 mo in 6 cases. A total of 474 fistulas were confirmed by surgery in the aforementioned patients, including 224 main fistulas, 250 branch pipes and 254 internal orifices. The CEUS + 360°-TRUS group had 96.87%, 90.41% and 90.14% diagnostic accuracy for the main tract, branch and internal orifice, which was statistically significant (p < 0.001) compared with the 85.00%, 70.00% and 72.46% for the TRUS group, respectively. The overall accuracy of Parks classification of anal fistula in the CEUS + 360°-TRUS group was significantly higher than that in the TRUS group (90.24% vs. 78.38%, p < 0.001). After 6 mo of follow-up, the recurrence rate in the CEUS + 360°-TRUS group was 4.87%, and the recurrence rate in the TRUS group was 18.91%. Percutaneous fistula CEUS combined with transrectal 360° 3-D imaging has significantly higher accuracy than conventional TRUS in the diagnosis of complex anal fistula, especially for anal fistula branches, internal openings and Parks classification and is beneficial in reducing post-operative occurrence of complex anal fistulas.

Reversible Splenial Lesion Syndrome as a Challenging Casuistry

The corpus callosum plays a vital role in brain function. In particular, in the trunk of the corpus callosum, in the course of various diseases, there may be temporary, reversible changes (reversible splenial lesion syndrome (RESLES)), as well as partially reversible and irreversible changes. This article discusses the differentiation of RESLES and other conditions with changes in the corpus callosum lobe, as well as the accompanying clinical symptoms. Moreover, a case report of a patient in whom the above changes appeared in the nuclear magnetic resonance (NMR) image is presented. A 20-year-old patient with the diagnosis of Ehlers-Danlos syndrome type VI was admitted to the psychiatric ward in an emergency because of psychomotor agitation, refusal to take food and fluids, delusional statements with a message, grandeur, and auditory hallucinations. In the performed magnetic resonance imaging (MRI) of the brain, the corpus callosum non-characteristic in T2-weighted images revealed a hyperintensive area, which was significantly hyperintensive in diffusion magnetic resonance (DWI) sequences and in apparent diffusion coefficient (ADC) sequences with reduced signal intensity and no signs of bleeding. The hypothesis of subacute ischemic stroke of the corpus callosum was presented. In the control MRI of the brain, changes in the corpus callosum completely regressed, thus excluding an ischemic etiology and favoring the diagnosis of RESLES. During hospitalization, the patient experienced significant fluctuations in mental status, with the dominant symptoms typical of the paranoid syndrome in the form of disturbances in the course and structure of thinking and perception, and a clear and stable improvement was obtained after the administration of long-acting intramuscular olanzapine. Taking into account the clinical and radiological picture, the age of the episode, the rapidity of the disease development, the persistence of its clinical symptoms after the withdrawal of radiological changes in the brain NMR image, as well as the significant improvement in the clinical condition after the introduction of antipsychotic drugs, the final diagnosis was made of schizophrenia.

Rituximab-induced mild encephalopathy with a reversible splanial lesion syndrome (MERS): an adverse effect to add to the list

Mild encephalopathy with a reversible splenial lesion syndrome (MERS) is a rare clinico-radiological entity. Rituximab (RTX)-induced MERS has never been described before. Herein, we report the case of a 33-year-old patient diagnosed since 2017, with an IgG4-RD. This diagnosis was retained in front of a prolonged fever, sicca syndrome, hepatic damage and renal pseudotumor associated to a high level of IGg4 at 2.8 g/l with suggestive renal histology. The patient was treated with corticosteroid therapy with persistence of renal impairment and nephrotic syndrome indicating RTX therapy. The patient received his first dose of RTX and presented few hours after, neurological and respiratory impairments. An infectious investigation comprising a SARS CoV-2 PCR and viral PCRs (VZV, Herpes and CMV) on cerebrospinal fluid (CSF) were negative. The HBV, HCV, HIV, Parvo B19, CMV, EBV, Herpes, Mycoplasma and syphilis serologies as well as Legionella antigenuria were also negative. The patient had received intravenous immunoglobulins (IVIG) and methylprednisone, associated with sodium valproate with favourable outcome. The diagnosis of MERS induced by RTX was retained in our patient according to clinical and radiological features. We herein report the first case of MERS following RTX in a patient treated for IgG4 related disease (IgG4-RD).

Cytotoxic lesion of corpus callosum in cerebral venous thrombosis—a case report

Background

Veiled by a myriad of monikers, there has been a growing recognition of cytotoxic lesions in the splenium of the corpus callosum as a distinct clinical entity. Despite the varied nomenclature, they all describe restricting callosal lesions on diffusion weighted magnetic resonance imaging with near-complete reversibility on therapy. The currently accepted terminology for these lesions is cytotoxic lesions of the corpus callosum (CLOCC). Only one case of CLOCC associated with cerebral venous Thrombosis has been reported in literature to date.

Case presentation

While these lesions have most commonly been linked to antiepileptic drug therapy, we describe a case of a young adult who developed CLOCC in the background of cerebral venous thrombosis. We hypothesize that occlusion of the posterior pericallosal vein led to the lesion in the splenium. Early institution of anticoagulation therapy resulted in complete reversal of the abnormality, leading to full clinical recovery.

Conclusion

Cytotoxic lesions of the corpus callosum may rarely be associated with cerebral venous thrombosis. We emphasize the need for greater awareness, early imaging and aggressive therapy of this potentially curable entity. We further highlight cerebral venous thrombosis as a cause for CLOCC.

Cytotoxic lesions of the corpus callosum in children: Etiology, clinical and radiological features, and prognosis

OBJECTIVES

Cytotoxic lesions of the corpus callosum (CLOCCs) are secondary lesions associated with entities like infection manifested by restricted diffusion on diffusion-weighted cranial magnetic resonance imaging. Our objectives are to evaluate the clinic-radiological spectrum of pediatric patients with cytotoxic lesions of the corpus callosum (CC).

METHODS

Children (0-18 years) admitted between February 2017 and May 2020 with splenial lesions showing diffusion restriction on MRI, either isolated or within involvement of other parts of the brain, were included retrospectively. The primary lesions of the CC (e.g. acute disseminated encephalomyelitis, acute ischemic infarction, and glioblastoma multiforme) were excluded. CLOCCs were divided into infection-associated, metabolic disorder-associated, and trauma-associated lesions, as well as CLOCCs involving other entities. Data were collected from the medical databases.

RESULTS

Forty-one patients were determined to have CLOCCs. Twenty-five (61%) were infection-associated, nine (22%) were trauma-associated, and three (7%) were metabolic disorder-associated cases, including 2 inherited disorders of metabolism. There were four (10%) patients with other entities, three with epilepsy, and one had an apparent life-threatening event. Six patients had a known etiology among the infection-associated group; one had multisystem inflammatory syndrome caused by COVID-19 and one had been infected by COVID-19 without any complications. All the infection-associated patients with isolated splenial lesions recovered totally, although six patients required intensive care hospitalization. Four trauma-associated patients had sequela lesions.

CONCLUSIONS

CLOCCs are associated with a spectrum of diseases, including the new coronavirus, COVID-19 infection. Infection-associated CLOCCs has the best prognosis, although severe cases may occur. Sequelae are possible based on the etiology.

Vertigo and Cytotoxic Lesions of the Corpus Callosum: Report with Review of the Literature

Background

The term cytotoxic lesions of the corpus callosum (CLOCCs) encompasses the entity reversible splenial lesion syndrome (RESLES). RESLES typically presents with altered levels of consciousness, seizures, and delirium and is distinguished radiographically by reversible focal lesions of the splenium of the corpus callosum. This disease pathology is associated with withdrawal of antiepileptic medications, infections, metabolic disturbance, or high-altitude cerebral edema.

Methods

We presented an otherwise healthy 72-year-old female that was consulted for an episode of isolated vertigo lasting four hours. Initial workup included CT head without contrast, CT angiogram head and neck, and MRI brain with and without contrast. The patient experienced recurrent episodes of vertigo at one and four months after initial presentation. An extensive workup at one month included a wide spectrum of laboratory tests and repeat imaging.

Results

Noncontrast CT of the head and CT angiogram of the head and neck were reassuring. MRI brain with and without contrast demonstrated hyperintensity in the splenium of the corpus callosum on FLAIR sequencing. A follow-up visit at one month revealed vitamin B12 deficiency and unchanged hyperintensity of the splenium of the corpus callosum. History and workup were negative for typical risk factors associated with RESLES.

Conclusion

An otherwise healthy patient who presented with an isolated episode of vertigo was discovered to demonstrate radiographic features consistent with RESLES but lacked the common risk factors and typical presentation of RESLES. This case expands the possible clinical presentation of RESLES and highlights the possible relationship between vitamin B12 deficiency and radiographic features of RESLES.

Reversible splenial lesion syndrome in sisters with sensorineural deafness as the first manifestation

Reversible splenial lesion syndrome (RESLES) is a rare clinico-radiological disorder syndrome with unclear pathophysiology. Here, two sisters with sensorineural deafness as the chief complaint diagnosed with RESLES was reported. Although the sisters had the disease successively, they were divided into two types on imaging by isolated lesions of splenium of the corpus callosum (SCC) and extensive lesions of the corpus callosum. The clinical manifestations and lesions on MRI disappeared after 6 months. The sensorineural deafness of the sisters in this article may be caused by transcallosal auditory pathway (TCAP) injury. Auditory handicap has been found in previous RESLES cases, indicating that we know little about the connection between the SCC and the auditory pathway, and further research is needed.

Leukoencephalopathy with transient splenial lesions related to 5-fluorouracil or capecitabine

BACKGROUND

5-Fluorouracil (5-FU) and its oral prodrug capecitabine have been rarely but consistently associated with acute central nervous system toxicity, including transient leukoencephalopathies involving the splenium of the corpus callosum.

METHODS

We performed a retrospective search in the French Pharmacovigilance database (FPDB) (January 1985-July 2020) for adult patients affected by solid cancers who developed acute toxic leukoencephalopathies with splenial lesions following treatment with 5-FU or capecitabine. A comprehensive review of the literature helped to circumstantiate our findings.

RESULTS

Our research in the FPDB identified six patients who, within 3 days from their first cycle of 5-FU or capecitabine, developed acute neurological symptoms, including gait ataxia (n = 4), dysarthria (n = 3), dysmetria (n = 2), headache (n = 2), and confusion (n = 2). Brain magnetic resonance imaging (MRI) showed T2/FLAIR (fluid-attenuated inversion recovery) hyperintensities in the corpus callosum, with diffusion restriction and no contrast enhancement, generally accompanied by additional alterations in the bilateral supratentorial white matter (n = 5). All patients discontinued the agent supposedly responsible for the toxicity and experienced full recovery after a median of 8.5 days from symptom onset. Control MRI showed a progressive normalization of acute MRI abnormalities. Literature review identified 26 cases with similar clinical and paraclinical characteristics. A single patient from the literature resumed 5-FU at a lower dose, with no recurrent toxicity.

CONCLUSIONS

5-FU and capecitabine might be responsible for acute leukoencephalopathies with transient splenial lesions that are generally reversible upon drug discontinuation. Resuming the agent responsible for toxicity might be feasible in selected cases, after having excluded dihydropyrimidine dehydrogenase deficiency, if expected benefits outweigh the risks.

Reversible Splenial Lesion Syndrome (RESLES) After Chemotherapy of Oral Tegafur-uracil in a Female With Locally Rectal Adenocarcinoma

A 42-year-old woman with reversible splenial lesion syndrome (RESLES) and rectal adenocarcinoma presented with sudden-onset delirium after the sixth cycle of her chemotherapy drug, oral tegafur-uracil (300 mg/m/day, days 1-14, with treatment cycle repeated every 21 days). Accompanied by the anti-CV2 antibody, paraphasia, and a loss of bimanual coordination, the patient's etiology and clinical manifestations of RESLES are unlike those of other reported cases of RESLES. Tegafur-uracil is an oral fluoropyrimidine that has a similar effect to 5-fluorouracil as an adjuvant treatment for colorectal cancer. The possibility that the toxicity of chemotherapeutic drugs may play a role in the pathogenesis of cytotoxic edema in the splenium of the corpus callosum and extracallosal white matter should be investigated further.

Clinically Mild Encephalopathy with a Reversible Splenial Lesion Caused by Influenza B Virus in an Unvaccinated Child

Reversible lesions involved in the splenium of corpus callosum (RESLES) are a rare clinic-radiological condition, whose pathogenesis could be related to infectious events (such as in mild encephalopathy with reversible splenial lesion-MERS), epilepsy or metabolic/electrolyte disorders. MERS is characterized by an acute mild encephalopathy associated with lesions in the splenium of corpus callosum on brain magnetic resonance imaging. Viral infections are commonly associated with this condition and type A influenza is the most common cause. The prognosis is generally favorable with spontaneous resolution of clinical and radiological abnormalities. We report a case report of type B influenza MERS in an 8-year-old unvaccinated girl with complete clinical and radiological recovery.

Reversible splenial lesion syndrome in children: clinical analysis and summary of a case series

Objective

Methods

Results

Conclusions

Clinically mild encephalitis/encephalopathy with reversible splenial lesion (MERS) associated with Mycoplasma pneumoniae pneumonia: An adult case and review of the literature

Mycoplasma pneumonia with mild CNS involvements should be considered of MERS, even in adult. From the case series, splenial single lesions by MRI and prodromal fever with varied neurological manifestations recovered completely by antibiotics were seen.

Reversible Splenial Lesion Syndrome with Some Novel Causes and Clinical Manifestations

Objective Reversible splenial lesion syndrome (RESLES) is a clinical radiological syndrome characterized by a reversible lesion of the splenium of the corpus callosum with a decreased apparent diffusion coefficient (ADC) value. The clinical manifestations of RESLES are diverse. Methods Fifteen cases of adult RESLES patients (10 males and 5 females) were retrospectively selected from the radiology system using the key word "corpus callosum" at a university-affiliated tertiary care hospital between May 1, 2015 and December 31, 2019. The possible precipitating factors, clinicoradiological findings and modified Rankin Scale (mRS) on follow-up were then analyzed. Results The patient ages ranged from 22 to 53 years old. The mean age was 34 years old. The most common neurological symptoms included headache (3/15), dizziness (3/15), first onset of seizure (3/15), paroxysmal blurred vision (2/15), vertigo (2/15), amnesia (2/15), and confused consciousness without seizure (2/15), followed by drowsiness (1/15), paresthesia (1/15), dysmetria (1/15) and dysarthria (1/15). The precipitating factors included infection, seizure, anti-epileptic treatment with levetiracetam, carbamazepine, valproate, hyperglycemia, hypoglycemia, cerebral venous sinus thrombosis, and rabies vaccine injection prior to the onset of RESLES. All cases were carefully followed up and had excellent prognoses. Conclusion RESLES manifests as variety of symptoms with less specificity and precipitating factors. Paroxysmal blurred vision may be a relatively specific symptom of RESLES. Levetiracetam, carbamazepine or valproate could be the cause of RESLES, exposure to the rabies vaccine could be another predisposing factors for RESLES as well. RESLES type 1 was therefore found to be highly "reversible" with an excellent prognosis.

Clinical analysis of reversible splenial lesion syndrome in Chinese adults: A retrospective study of 11 cases

Reversible splenial lesion syndrome (RESLES) is a clinico-radiological entity that defines a reversible lesion in the splenium of the corpus callosum (SCC) on magnetic resonance imaging (MRI). The clinical and radiological characteristics of RESLES are poorly defined and most RESLES literature is in the form of case reports. We reviewed the clinical and radiological data from 11 RESLES patients in order to more clearly describe the characteristics of this disorder in adults.Patients included in this study were diagnosed with RESLES from May 2012 to March 2018. We collected clinical, imaging, and laboratory data of 11 adult patients from Neurology Department of the Affliated Yantai Yuhuangding Hospital of Qingdao University. After analyzing various clinico-radiological features and laboratory parameters, including serum sodium, pathogen testing, cerebrospinal fluid (CSF) studies, electroencephalography (EEG), and MRI findings, we made a diagnosis of RESLES based on the criteria proposed previously by Garcia-Monco et al.Of the 11 patients, 7 (63.63%) were male and 4 (36.36%) were female, ranging in age from 24 to 62 years with an average age of 31.48 ± 11.47 years. Seven cases occurred in the months of winter and spring (December-March). The primary clinical symptoms were headache, seizure, disturbance of consciousness, mental abnormality, and dizziness. All 11 patients had lesions in the SCC and all the lesions disappeared or significantly improved on follow-up imaging that was done within a month of symptom resolution.We found 5 (45.45%) patients had a CSF opening pressure >180 mmH2O, in addition to elevated protein and(or) leukocytes levels in 3 (27.27%) patients. The serum sodium concentration in 6 (54.55%) patients was low (<137 mmol/L) and EEG showed nonspecific slowing in waves 4 (36.36%) patients.When we encounter clinical manifestations such as headache accompanied with mental symptoms, disturbance of consciousness or epilepsy, and brain MRI finds lesions of the corpus callosum, we should consider whether it is RESLES. In order to find out the possible cause of the disease, we should carefully inquire about the history of the disease, complete etiology examination, and CSF tests. Of course, it is one of the necessary conditions for the diagnosis that the lesions in the corpus callosum are obviously relieved or disappeared.

Mild Encephalitis/Encephalopathy with a Reversible Isolated Splenial Lesion (MERS) in Adult Patients: A Small Case Series

BACKGROUND

Mild encephalitis/encephalopathy with a reversible isolated splenial lesion (MERS) is a rare and complex clinico-radiological condition that aggregates various diseases. From a geographical point of view, most cases have been reported in Asia, especially in Japan. However, a very limited number of studies have properly evaluated Chinese patients diagnosed with MERS.

METHODS

Putative encephalitis/encephalopathy patients affected by a reversible isolated SCC lesion, as detected by magnetic resonance imaging (MRI), were retrospectively evaluated. Specifically, we reviewed extensive patient data, including prodromal and neurologic symptoms, neurologic examinations, MRI and electroencephalography (EEG) findings, laboratory results, treatments, and prognosis.

RESULTS

Six clinically mild encephalitis/encephalopathy patients, affected by a reversible isolated SCC lesion, were identified in a cohort of 22 patients. Six patients presented fever symptoms before the onset of neurological manifestations. Initial MRI data exhibited isolated SCC lesions with isointense or slightly hypointense on T1WI, hyperintense on T2WI, Flair, and DWI, as well as decreased ADC values, without contrast enhancement. EEG data indicated abnormalities (3/4), as well as elevated serum inflammatory markers (5/6) and hyponatremia (4/6). Cell content and protein yields were normal or slightly increased in the CSF of 6 patients, excluding one episode of significant increase in cell number. Patients were treated with corticosteroids, antivirals, and antibiotics, resulting in their full clinical recovery. SCC lesions mostly disappeared in all patients.

CONCLUSION

In our study, the clinical features identified in all affected patients were mostly identical, which consisted of relatively mild CNS manifestations with a promising prognostic status.

Reversible Splenial Lesion Syndrome Associated with Encephalitis/Encephalopathy and Hyponatremia

Reversible splenial lesion syndrome (RESLES) is a rare occurrence with a broad clinical and radiological spectrum due to several conditions and diseases. Generally, clinical symptoms of RESLES include mildly altered states of consciousness, delirium, and seizures. RESLES can be shown in conjunction with central nervous system infections, especially in children. Hyponatremia is also described as a potential cause of reversible splenial lesions. Reversible signal changes on diffusion-weighted images are detected in patients for diagnosis. The prognosis is usually good but it depends on the underlying disease, neurological and imaging findings. Here we present two pediatric patients with RESLES accompanied by hyponatremia.

Treatment-related transient splenial lesion of the Corpus Callosum in patients with neuropsychiatric disorders: a literature overview with a case report

Introduction: Transient-localized lesions of the splenium of the corpus callosum (SCC) have been described in various clinical conditions, some of them being attributed to the withdrawal of psychotropic drugs. The pathophysiology of the lesion reflects cytotoxic edema and reversible demyelination.Areas covered: The present article aimed at reviewing cases of transient SCC lesion exclusively related to changes in pharmacotherapy. It also reports the original case of a patient receiving a complex psychopharmacological therapy who developed a transient SCC lesion investigated by magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), and pharmacogenetic profiling.Expert opinion: To date, only one review on the subject has been published, analyzing 22 cases of transient SCC lesion arising in epileptic patients on antiepileptic therapy. It hypothesized that the nature of the lesion is a cytotoxic edema and the cases described in the subsequent 14 years seem to support this hypothesis. The authors reported the case of an Italian-Egyptian patient who developed a transient SCC lesion after the rapid withdrawal of Carbamazepine and Lurasidone. The lesion completely disappeared from the MRI performed after 1 month. Patient's ethnic group and its pharmacogenetic profile were considered as possible causes of altered drug metabolism and, likely, of the SCC lesion.

Combining lexical and context features for automatic ontology extension

BACKGROUND

Ontologies are widely used across biology and biomedicine for the annotation of databases. Ontology development is often a manual, time-consuming, and expensive process. Automatic or semi-automatic identification of classes that can be added to an ontology can make ontology development more efficient.

RESULTS

We developed a method that uses machine learning and word embeddings to identify words and phrases that are used to refer to an ontology class in biomedical Europe PMC full-text articles. Once labels and synonyms of a class are known, we use machine learning to identify the super-classes of a class. For this purpose, we identify lexical term variants, use word embeddings to capture context information, and rely on automated reasoning over ontologies to generate features, and we use an artificial neural network as classifier. We demonstrate the utility of our approach in identifying terms that refer to diseases in the Human Disease Ontology and to distinguish between different types of diseases.

CONCLUSIONS

Our method is capable of discovering labels that refer to a class in an ontology but are not present in an ontology, and it can identify whether a class should be a subclass of some high-level ontology classes. Our approach can therefore be used for the semi-automatic extension and quality control of ontologies. The algorithm, corpora and evaluation datasets are available at https://github.com/bio-ontology-research-group/ontology-extension.

Reversible lesion in the splenium of the corpus callosum

AIM OF REVIEW

The presence of isolated, reversible lesions in the splenium of the corpus callosum (SCC) is essential to confirm the diagnosis of mild encephalitis/encephalopathy. The lesions usually heal within a month after the onset of neurological symptoms. Magnetic resonance imaging (MRI) has increasingly been used as a diagnostic tool, which has led to the publication of an increasing number of case reports. These have highlighted some inconsistencies about encephalitis/encephalopathy. First, the condition is not always mild and may be severe. Second, reversible lesions in the SCC have been identified in various diseases and conditions other than viral encephalitis/encephalopathy. Third, lesions in SCC are not always completely reversible. On this note, this review describes the specific clinical and radiological features of encephalitis/encephalopathy.

FINDINGS

The reversible lesion in SCC is an MRI finding observable in a wide variety of diseases and conditions. Thus, it should be considered as a secondary change rather than a peculiar feature associated with mild encephalitis/encephalopathy. If reversible lesions are present in the SCC, the symptoms and prognosis are not necessarily favorable, with manifestations of encephalitis/encephalopathy varying from absent to severe. Neuroradiological features that appear as isolated high-intensity signals on diffusion-weighted images and a decreased apparent diffusion coefficient of the lesion might indicate a diagnosis of cytotoxic edema. Findings of previous studies suggest that cytokine-mediated cytotoxic edema of the SCC may be an important pathophysiological manifestation of this condition.

CONCLUSION

The reversible lesions in the SCC found on MRI are not exclusive to encephalitis/encephalopathy but may be secondary to other disorders.

Mild encephalitis/encephalopathy with a reversible splenial lesion secondary to encephalitis complicated by hyponatremia: A case report and literature review

RATIONALE

Mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is an infection-associated encephalitis/encephalopathy syndrome that is predominately caused by a virus. MERS has no direct association with central nervous system (CNS) infections or inflammation. Non-CNS infections may cause reversible lesion in the splenium of corpus callosum. Recently, there have been reports of many patients with hyponatremia related MERS. Interleukin-6 (IL-6) was also found elevated in serum and in cerebrospinal fluid (CSF) in patients with MERS. The role of IL-6 in the non-osmotic release of vasopressin is crucial. Persistent hyponatremia may be linked to this effect. The following is a case report of MERS secondary to encephalitis, complicated by hyponatremia. We will summarize the latest research and progress regarding MERS.

PATIENT CONCERNS

A 31-year-old man was admitted to our department with a 5-day history of fever and headache. His initial diagnosis was encephalitis and hyponatremia; during this period the patient also developed MERS secondary to the encephalitis.

DIAGNOSES

Encephalitis was diagnosed by reviewing the history of fever, headache, neck rigidity and Kerning sign (+) on clinical examination. Lab tests revealed: serum VCA IgG (+), EBNA-1 IgG (-), EBV IgM (-), and inflammation in the analysis of CSF. Cranial MRI+C showed that the blood vessels on the surface of the brain were obviously increasing and thickening and diffuse slow waves were detected on the electroencephalogram (EEG). The patient's hyponatremia aggravated on the third day of hospitalization. On the fourth day of hospitalization, the patient was somnolent, apathetic, and slow. Magnetic resonance imaging (MRI) of the brain, with a T2-weighted fluid attenuated inversion recovery image, showed high-signal intensity in the splenium of the corpus callosum (SCC) on the fifth day of hospitalization. Diffusion-weighted imaging (DWI) showed splenial hyperintensity as a "boomerang sign" and reduced diffusion on apparent diffusion coefficient (ADC) maps. Cranial MRI findings returned to normal after 1 month. The diagnosis of MERS was confirmed.

INTERVENTIONS

We administered an intravenous drip infusion of acyclovir and prescribed oral sodium supplementation.

OUTCOMES

The patient's neurological symptoms gradually improved. The MRI lesion in the SCC disappeared on the 30th day.

LESSONS

In patients with encephalitis accompanied by hyponatremia, elevated IL-6 or urinary β2-microglobulin (β2MG), and exacerbations such as sudden somnolence, delirium, confusion, and seizures, the possibility of secondary MERS should be investigated, in addition to the progression of encephalitis.

Reversible splenial lesion syndrome associated with acute Mycoplasma pneumoniae-associated encephalitis: A report of four cases and literature review

Reversible splenial lesion syndrome (RESLES) is a rare clinico-radiological syndrome that is defined as reversible lesions that involve the splenium of the corpus callosum (SCC). RESLES has been reported in patients with a broad spectrum of diseases and conditions, including infections, hypoglycemia and poisoning. The present report described four RESLES cases triggered by Mycoplasma pneumoniae (M. pneumoniae) and discussed the associated diagnostic challenges. Four cases of acute M. pneumoniae-associated encephalitis that displayed RESLES were reviewed. The clinical presentations were nonspecific in these patients. However, magnetic resonance imaging (MRI) revealed consistent lesions in the SCC with a hyperintensity in diffusion-weighted imaging (DWI) and hypointensities in T1WI, which disappeared after a variable lapse. Treatment with azithromycin or combined treatment with immunomodulatory agents if necessary led to a good prognosis. The present findings indicated that radiological diagnosis of RESLES should be considered in patients with M. pneumoniae-associated encephalitis. Furthermore, serum Mycoplasma antibody is important for the diagnosis of M. pneumoniae-associated encephalitis.

Agraphia with reversible splenial corpus callosum lesion caused by hypoglycemia

BACKGROUND

Neurological manifestations caused by hypoglycemia range from reversible focal deficits and transient encephalopathy to irreversible coma or death. Recently, high signal intensity lesions in the splenium of the corpus callosum on diffusion-weighted magnetic resonance imaging were reported in adults experiencing hypoglycemia. However, patients presenting with agraphia are rare.

SUBJECT AND METHODS

We examined a 17-year-old left-handed female patient with type 1 diabetes who exhibited transient left agraphia with a reversible splenium lesion of the corpus callosum on diffusion-weighted imaging caused by hypoglycemia, which was improved with blood glucose management alone.

CONCLUSION

This rare case indicates that agraphia, a sign of callosal disconnection syndrome, can result from a reversible splenial lesion of the corpus callosum caused by hypoglycemia.

Reversible lesions of the corpus callosum with initially restricted diffusion in a series of Caucasian children

BACKGROUND

Reversible lesions of the corpus callosum with initial restricted diffusion on diffusion-weighted imaging (DWI) are rare and mainly described in the south Asiatic population.

OBJECTIVE

The purpose of this study was to describe the clinical presentation, imaging findings, prognosis and etiology of transient restricted diffusion lesions of the corpus callosum in a series of Caucasian children.

MATERIALS AND METHODS

Seven children presenting with a transient restricted DWI lesion of the corpus callosum were included. Their clinical presentations and paraclinical examinations were investigated in addition to their MRI findings during the acute phase and at follow-up.

RESULTS

Five patients initially presenting with prodromal flu-like symptoms were diagnosed with mild encephalopathy with reversible corpus callosum lesions, three of which were due to the influenza virus. For two patients (twins) with a stroke-like presentation and without febrile illness, a central nervous system manifestation of X-linked Charcot-Marie-Tooth disease with connexin 32 mutation was diagnosed. All patients had a good clinical prognosis without clinical sequelae or residual MRI lesion for all patients at follow-up.

CONCLUSION

A transient lesion of the corpus callosum with restricted diffusion should prompt the radiologist to suggest an infectious trigger in children. The prognosis of these patients was good with normalization of clinical symptoms and MRI without any specific treatment.

[Syndrome of mild encephalopathy with a reversible splenial corpus callosum lesion]

Mild encephalopathy with a reversible splenial lesion (MERS) is a clinico-radiological syndrome that has been associated with a variety of underlying etiologies including viral and bacterial infections, epilepsy and antiepileptic drug cessation, hypoglycemia and electrolyte imbalance. We report a case of a 24-year-old woman who had an isolated splenial lesion in the corpus callosum on neuroimaging associated with MERS.

Reversible splenial lesion syndrome (RESLES) coinciding with cerebral venous thrombosis: a report of two cases

A total of two postpartum women with no noteworthy medical history presented with persistent headache. Brain magnetic resonance imaging (MRI) of both revealed extensive cerebral venous thrombosis, concurrently with abnormal signals of the splenium of the corpus callosum (SCC): The splenium appeared hyperintense on T2-weighted sequences, fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted imaging (DWI) imaging, and hypointense on T1 sequences and apparent diffusion coefficient (ADC) map. The patients were given thrombolytic therapy. Clinically, both patients achieved recovery with no neurologic sequelae, and follow-up MRI revealed complete resolution of the lesion in the SCC at day 36 and day 37 after initial presentation, respectively.

Mild encephalitis/encephalopathy with reversible splenial lesion (MERS) in adults-a case report and literature review

Background

Mild encephalitis/encephalopathy with reversible splenial lesion (MERS) is a rare clinico-radiological entity characterized by the magnetic resonance imaging (MRI) finding of a reversible lesion in the corpus callosum, sometimes involved the symmetrical white matters. Many cases of child-onset MERS with various causes have been reported. However, adult-onset MERS is relatively rare. The clinical characteristics and pathophysiologiccal mechanisms of adult-onset MERS are not well understood. We reviewed the literature on adult-onset MERS in order to describe the characteristics of MERS in adults and to provide experiences for clinician.

Methods

We reported a case of adult-onset MERS with acute urinary retension and performed literature search from PubMed and web of science databases to identify other adult-onset MERS reports from Januarary 2004 to March 2016. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was followed on selection process. And then we summarized the clinico-radiological features of adult-onset MERS.

Results

Twenty-nine adult-onset MERS cases were reviewed from available literature including the case we have. 86.2% of the cases (25/29) were reported in Asia, especially in Japan. Ages varied between 18 and 59 years old with a 12:17 female-to-male ratio. The major cause was infection by virus or bacteria. Fever and headache were the most common clinical manifestation, and acute urinary retention was observed in 6 patients. All patients recovered completely within a month.

Conclusion

Adult-onset MERS is an entity with a broad clinico-radiological spectrum because of the various diseases and conditions. There are similar characteristics between MERS in adults and children, also some differences.

Nervous System Abnormalities and Legionnaire's Disease

Although patients with Legionnaire's disease frequently develop alterations of consciousness, this is no more frequent than in patients hospitalized with other, equally severe forms of bacterial pneumonia. Legionella meningitis occurs rarely, if ever. Patients with Legionnaire's are susceptible to critical illness polyneuropathy/myopathy, as are other critically ill patients. Legionnaire's patients may develop MRI hyperdensities in the splenium of the corpus callosum, as may other patients with severe infections. Patients with Legionnaire's may be at increased risk of, and rarely develop, immune-mediated multifocal brain (acute disseminated encephalomyelitis) or peripheral nerve disease (Guillain-Barré syndrome).

Mild encephalitis/encephalopathy with reversible splenial lesion (MERS) associated with Streptococcus pneumoniae Bacteraemia

Mild encephalopathy with a reversible splenial lesion (MERS) is a clinico-radiological syndrome that can be related to infectious and non-infectious conditions. Patients present with mild neurological symptoms, and magnetic resonance imaging typically demonstrate a reversible lesion with transiently reduced diffusion in the splenium of the corpus callosum. Here, we describe MERS in a 10-year-old boy who presented with fever and consciousness and who completely recovered within a few days. Streptococcus pneumoniae was the causative agent. Although viruses (especially influenza A and B) are the most common pathogen of MERS, for proper management, bacteria should be considered, as they may also lead to this condition.

Marked elevation of urinary β2-microglobulin in patients with reversible splenial lesions: A small case series

The magnetic resonance imaging findings of reversible isolated lesions with transiently reduced diffusion in the splenium of corpus callosum of patients with a wide spectrum of pathological conditions are referred to as reversible splenial lesion syndrome (RESLES). Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is probably included within the spectrum of RESLES; however, its exact pathophysiology is not known. Here, we describe three patients with MERS and one patient with RESLES, all of whom showed elevated urinary β2-microglobulin regardless of diagnosis and presence of pathogens. Elevated urinary β2-microglobulin suggested that an excessive immune response might play a role in the pathophysiology of reversible splenial lesions.

Reversible Cerebral Vasoconstriction Syndrome with Transient Splenial Lesions after Delivery

Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by segmental vasospasm and it is often accompanied by either posterior reversible encephalopathy syndrome or stroke. However, other MRI abnormalities have rarely been reported. A 28-year-old woman presented with a thunderclap headache immediately after delivery; MRI showed segmental vasoconstriction and an abnormal signal in the splenium of the corpus callosum. Neuroimaging abnormalities normalized 20 days after the first examination. Only two cases of RCVS with transient splenial lesions (TSL) have so far been reported. Both cases occurred postpartum like ours, indicating that delivery may be a trigger for the development of both TSLs and RCVS.