Cytotoxic Lesions Research Articles

Complete neurological recovery from fat embolism syndrome in sickle cell disease after sequential red cell exchange transfusion and therapeutic plasma exchange

Fat embolism syndrome in sickle cell disease is associated with great mortality, while more than half of survivors suffer severe neurological sequelae. Release of fat droplets leads to obstruction of the microcirculation as well as generation of proinflammatory cytokines that can cause direct tissue injury. Red cell exchange transfusion can be life-saving but the addition of therapeutic plasma exchange may further improve outcomes by removing such inflammatory mediators. Here, we describe the case of a 27-year-old male patient with sickle cell anaemia presenting with typical features of fat embolism syndrome including neurological involvement with greatly reduced level of consciousness. MRI of his brain showed multiple widespread microhemorrhages giving the characteristic "star field" pattern but also a cytotoxic lesion of the corpus callosum, known to be the result of direct neurotoxicity by proinflammatory cytokines. The patient underwent emergency red cell exchange transfusion leading only to modest clinical improvement but fully regained consciousness after three cycles of therapeutic plasma exchange. This case highlights the deleterious effect of the hyperinflammatory state characteristic of many sickle cell complications and supports further exploring the potential benefit from plasma exchange as an adjunct to red cell exchange in order to remove proinflammatory cytokines during acute complications of sickle cell disease.

The dark side of homology-directed repair

DNA double strand breaks (DSB) are cytotoxic lesions that can lead to genome rearrangements and genomic instability, which are hallmarks of cancer. The two main DSB repair pathways are non-homologous end joining and homologous recombination (HR). While HR is generally highly accurate, it has the potential for rearrangements that occur directly or through intermediates generated during the repair process. Whole genome sequencing of cancers has revealed numerous types of structural rearrangement signatures that are often indicative of repair mediated by sequence homology. However, it can be challenging to delineate repair mechanisms from sequence analysis of rearrangement end products from cancer genomes, or even model systems, because the same rearrangements can be generated by different pathways. Here, we review homology-directed repair pathways and their consequences. Exploring those pathways can lead to a greater understanding of rearrangements that occur in cancer cells.

Too Hot to Handle: Early Temperature Management and Unique Treatment of Hyperpyrexia in SARS-CoV2 Encephalopathy.

ABSTRACTA 45-year-old otherwise healthy active duty male was admitted to the medical intensive care unit for severe acute respiratory syndrome-coronavirus 2 (SARS-CoV2) encephalopathy associated with hyperpyrexia. Magnetic resonance imaging findings demonstrated cytotoxic lesions primarily at the midline of the splenium of corpus callosum (CLOCC). Similar cases involving hyperpyrexia in the setting of SARS-CoV2 infection have demonstrated exceedingly high-mortality outcomes. Three mechanisms exist as to the likely underlying pathophysiology of SARS-CoV2-induced hyperpyrexia: direct brain injury, persistent immune dysregulation of cytokines, and vascular thrombosis. To date, no cases have reported imaging findings consistent with SARS-CoV2-induced brain injury leading to hyperpyrexia. Magnetic resonance imaging findings in this case, however, may finally elucidate the underlying mechanism for hyperpyrexia in this population. Magnetic resonance imaging findings in this case show diffusion restriction of the corpus callosum without evidence of any Central Nervous System (CNS) vessel abnormality. Given that hyperpyrexia has a clear association with increased mortality and morbidity in the SARS-CoV2 infected population, the decision to initiate steroids and remdesivir regardless of respiratory status was made for the concern for severe SARS-CoV2 infection as demonstrated by the CLOCC. Additional cases will be needed to assess their potential use as a radiological marker of disease burden.

COVID-19 Associated Transient Cytotoxic Lesion of the Corpus Callosum: Report of Two Cases and Current Literature Review

Cytotoxic lesion of the corpus callosum (CLOCC) stems from a variety of causes such as malignancies, drug treatments, metabolic disorders, subarachnoid hemorrhage, and infections, and often presents as encephalitis or encephalopathy. During this pandemic, we saw 2 cases with this lesion;the first one was a 42-year-old male who presented to the emergency department with complaints of headache, fever, and cough. There was a ground-glass opacity in the thorax computed tomography, and diffusion restriction was found in the corpus callosum splenium in the cranial magnetic resonance imaging (MRI) performed for headache that did not resolve with analgesic treatment during hospitalization due to the preliminary diagnosis of Coronavirus diseases-2019 (COVID-19) pneumonia. In the second case, Severe Acute Respiratory syndrome Coronavirus-2 polymerase chain reaction was found to be positive in the examinations performed during his admission to the emergency service due to weakness and presyncope, and diffusion restriction was observed in the corpus callosum splenium like the first case in cranial imaging. The follow-up cranial MRI was normal in both cases, so they were diagnosed with CLOCC. We aimed to report the present cases with COVID-19 associated CLOCC since they presented only as a headache and a presyncope without any mental deterioration.

A review of neuroradiological abnormalities in patients with coronavirus disease 2019 (COVID-19).

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to various neurological manifestations. There is an urgent need for a summary of neuroimaging findings to accelerate diagnosis and treatment plans. We reviewed prospective and retrospective studies to classify neurological abnormalities observed in patients with the SARS-CoV-2 infection.MethodsThe relevant studies published in Scopus, PubMed and Clarivate Analytics databases were analysed. The search was performed for full-text articles published from 23 January 2020 to 23 February 2021.ResultsIn 23 studies the number of patients with SARS-CoV-2 infection was 20,850 and the number of patients with neurological manifestations was 1996 (9.5%). The total number of patients with neuroradiological abnormalities was 602 (2.8%). SARS-CoV-2 has led to various neuroimaging abnormalities which can be categorised by neuroanatomical localisation of lesions and their main probable underlying pathogenesis. Cranial nerve and spinal root abnormalities were cranial neuritis and polyradiculitis. Parenchymal abnormalities fell into four groups of: (a) thrombosis disorders, namely ischaemic stroke and sinus venous thrombosis; (b) endothelial dysfunction and damage disorders manifested as various types of intracranial haemorrhage and posterior reversible encephalopathy syndrome; (c) hypoxia/hypoperfusion disorders of leukoencephalopathy and watershed infarction; and (d) inflammatory disorders encompassing demyelinating disorders, encephalitis, vasculitis-like disorders, vasculopathy and cytotoxic lesions of the corpus callosum. Leptomeninges disorders included meningitis. Ischaemic stroke was the most frequent abnormality in these studies.ConclusionThe review study suggests that an anatomical approach to the classification of heterogeneous neuroimaging findings in patients with SARS-CoV-2 and neurological manifestations would lend itself well for use by practitioners in diagnosis and treatment planning.

Encephalopathy and Cytotoxic Lesion of the Corpus Callosum Associated with Cytokine Storm in COVID-19: A Case Report

One hypothesis is that the activation of innate immunity and release of cytokines breaks down the blood brain barrier (BBB) and causes neuroinflammation. Here, I present a case of COVID-19 associated MIS-C (multisystem inflammatory syndrome in children) with neurological complications manifesting as encephalopathy and a cytotoxic lesion of the corpus callosum (CLOCC) on the brain MRI, in association with extremely elevated levels of circulating interleukin-6 (IL-6), and soluble interleukin-2 receptor (sIL2R).

1H, 13C, 15N backbone resonance assignment for the 1\u2013164 construct of human XRCC4

DNA double-strand breaks (DSBs) represent the most cytotoxic DNA lesions, as—if mis- or unrepaired—they can cause cell death or lead to genome instability, which in turn can cause cancer. DSBs are repaired by two major pathways termed homologous recombination and non-homologous end-joining (NHEJ). NHEJ is responsible for repairing the vast majority of DSBs arising in human cells. Defects in NHEJ factors are also associated with microcephaly, primordial dwarfism and immune deficiencies. One of the key proteins important for mediating NHEJ is XRCC4. XRCC4 is a dimer, with the dimer interface mediated by an extended coiled-coil. The N-terminal head domain forms a mixed alpha–beta globular structure. Numerous factors interact with the C-terminus of the coiled-coil domain, which is also associated with significant self-association between XRCC4 dimers. A range of construct lengths of human XRCC4 were expressed and purified, and the 1–164 variant had the best NMR properties, as judged by consistent linewidths, and chemical shift dispersion. In this work we report the 1H, 15 N and 13C backbone resonance assignments of human XRCC4 in the solution form of the 1–164 construct. Assignments were obtained by heteronuclear multidimensional NMR spectroscopy. In total, 156 of 161 assignable residues of XRCC4 were assigned to resonances in the TROSY spectrum, with an additional 11 resonances assigned to His-Tag residues. Prediction of solution secondary structure from a chemical shift analysis using the TALOS + webserver is in good agreement with the published X-ray crystal structures of this protein.

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

ObjectivesCytotoxic 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). MethodsChildren (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. ResultsForty-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. ConclusionsCLOCCs 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.

Inhibition of DNA Repair in Combination with Temozolomide or Dianhydrogalactiol Overcomes Temozolomide-Resistant Glioma Cells.

Simple SummaryGlioblastoma is the most prevalent and lethal brain tumor. Temozolomide is usually used for the treatment of glioblastoma. The poor prognosis of the tumor is due to drug resistance and tumor heterogeneity. The mechanism of the resistance to temozolomide is various within the same tumor. The aim of the study was to clarify the mechanism of temozolomide resistance and find methods to overcome temozolomide resistance in glioma. Inhibition of DNA repair (homologous recombination or base excision repair) resensitized resistant cells harboring different resistance mechanism to temozolomide. Additionally, a bifunctional DNA-targeting agent, dianhydrogalactiol, showed anti-tumor effect independent of MGMT and mismatch repair status. Further, inhibition of checkpoint or homologous recombination enhanced dianhydrogalactiol-induced cytotoxicity in temozolomide-resistant glioma cells. Although resistance to temozolomide is clinically important issue, selecting suitable treatments for resistance mechanism can improve the prognosis of glioma.Resistance to temozolomide and intratumoral heterogeneity contribute to the poor prognosis of glioma. The mechanisms of temozolomide resistance can vary within a heterogeneous tumor. Temozolomide adds a methyl group to DNA. The primary cytotoxic lesion, O6-methylguanine, mispairs with thymine, leading to a futile DNA mismatch repair cycle, formation of double-strand breaks, and eventual cell death when O6-methylguanine DNA methyltransferase (MGMT) is absent. N7-methylguanine and N3-methyladenine are repaired by base excision repair (BER). The study aim was to elucidate temozolomide resistance mechanisms and identify methods to overcome temozolomide resistance in glioma. Several temozolomide-resistant clones were analyzed. Increased homologous recombination and mismatch repair system deficiencies contributed to temozolomide resistance. Inhibition of homologous recombination resensitized resistant cells with high homologous recombination efficiency. For the mismatch repair-deficient cells, inhibition of BER by PARP inhibitor potentiated temozolomide-induced cytotoxicity. Dianhydrogalactiol is a bifunctional DNA-targeting agent that forms N7-alkylguanine and inter-strand DNA crosslinks. Dianhydrogalactiol reduced the proliferation of cells independent of MGMT and mismatch repair, inducing DNA double-strand breaks and apoptosis in temozolomide-resistant cells. Further, inhibition of chk1 or homologous recombination enhanced dianhydrogalactiol-induced cytotoxicity in the cells. Selecting treatments most appropriate to the types of resistance mechanisms can potentially improve the prognosis of glioma.

COVID-19 and neuroinflammation: a literature review of relevant neuroimaging and CSF markers in central nervous system inflammatory disorders from SARS-COV2.

BackgroundThe literature on neurological manifestations in COVID-19 patients has been rapidly increasing with the pandemic. However, data on CNS inflammatory disorders in COVID-19 are still evolving. We performed a literature review of CNS inflammatory disorders associated with coronavirus disease-2019 (COVID-19).MethodsWe screened all articles resulting from a search of PubMed, Google Scholar and Scopus, using the keywords; “SARS-CoV-2 and neurological complication”, “SARS-CoV-2 and CNS Complication” looking for reports of transverse myelitis, longitudinally extensive transverse myelitis, neuromyelitis optica, myelitis, Myelin Oligodendrocyte Glycoprotein Antibody Disorder (MOGAD), Acute Disseminated Encephalomyelitis (ADEM), Acute Hemorrhagic Necrotizing Encephalitis/Acute Hemorrhagic Leukoencephalitis (AHNE/AHLE), Cytotoxic lesion of the Corpus Callosum/Mild Encephalopathy Reversible Splenium Lesion(CLOCC/MERS) and Optic neuritis published between December 01, 2019 and March 15, 2021.ResultsOur literature search revealed 43 patients meeting the diagnosis of myelitis, including Transverse Myelitis, ADEM, AHNE/AHLE or CLOCC/MERS and Optic neuritis. Acute myelitis was most commonly associated with non-severe COVID-19 and all reported cases of AHNE/AHLE had severe COVID-19 infection. Based on IDSA/ATS criteria of either requiring vasopressor for septic shock or mechanical ventilation, 49% (n = 18) patients were considered to have a severe COVID infection. There were 7 (n = 19%) fatalities.ConclusionTo our knowledge, this is among the first reviews that includes the clinical features, neuroimaging, CSF findings and outcomes in COVID-19-associated CNS inflammatory disorders. Our observational review study reveals that although rare, myelitis, ADEM, AHNE and CLOCC can be associated with COVID-19 infection. Further studies using MRI imaging and CSF analysis in early diagnosis and intervention of these disorders are warranted.

Ubiquitylation in DNA double-strand break repair

Genome integrity is constantly challenged by various DNA lesions with DNA double-strand breaks (DSBs) as the most cytotoxic lesions. In order to faithfully repair DSBs, DNA damage response (DDR) signaling networks have evolved, which organize many multi-protein complexes to deal with the encountered DNA damage. Spatiotemporal dynamics of these protein complexes at DSBs are mainly modulated by post-translational modifications (PTMs). One of the most well-studied PTMs in DDR is ubiquitylation which can orchestrate cellular responses to DSBs, promote accurate DNA repair, and maintain genome integrity. Here, we summarize the recent advances of ubiquitin-dependent signaling in DDR and discuss how ubiquitylation crosstalks with other PTMs to control fundamental biological processes in DSB repair.

New Faces of old Friends: Emerging new Roles of RNA-Binding Proteins in the DNA Double-Strand Break Response.

DNA double-strand breaks (DSBs) are highly cytotoxic DNA lesions. To protect genomic stability and ensure cell homeostasis, cells mount a complex signaling-based response that not only coordinates the repair of the broken DNA strand but also activates cell cycle checkpoints and, if necessary, induces cell death. The last decade has seen a flurry of studies that have identified RNA-binding proteins (RBPs) as novel regulators of the DSB response. While many of these RBPs have well-characterized roles in gene expression, it is becoming increasingly clear that they also have non-canonical functions in the DSB response that go well beyond transcription, splicing and mRNA processing. Here, we review the current understanding of how RBPs are integrated into the cellular response to DSBs and describe how these proteins directly participate in signal transduction, amplification and repair at damaged chromatin. In addition, we discuss the implications of an RBP-mediated DSB response for genome instability and age-associated diseases such as cancer and neurodegeneration.

Modeling DNA trapping of anticancer therapeutic targets using missense mutations identifies dominant synthetic lethal interactions

Significance Although inhibitor-mediated trapping of protein on DNA is a viable anticancer therapeutic strategy, there are very few examples of this approach with clinical applications. One limitation to expanding this strategy is the use of gene knockout-based modeling of chemical inhibition. Instead, we propose mimicking the trapping mechanism of DNA-associated cancer targets using dominant missense mutations. These mutations inhibit enzymatic activity without impacting DNA binding and generate cytotoxic lesions in the presence of the wild-type protein. Trapped cytotoxic lesions impact DNA processes and sensitize cells to deficiencies in some DNA-associated pathways. We identified genetic backgrounds that cannot tolerate the dominant mutant proteins and demonstrated a requirement for DNA or protein binding to maintain this cytotoxicity.

Clinical Significance of Cytotoxic Lesions of the Corpus Callosum in Subarachnoid Hemorrhage Patients: A Retrospective Analysis

Introduction: Cytotoxic lesions of the corpus callosum are secondary lesions induced by significant increases in cytokine levels in the brain and are associated with subarachnoid hemorrhage (SAH). However, their clinical significance in SAH patients remains unclear. Methods: We retrospectively analyzed SAH patients who were treated in our hospital and evaluated between-group differences in the backgrounds, clinical findings, and outcomes between SAH patients who developed cytotoxic lesions of the corpus callosum and those who did not. We further compared patients who achieved good outcomes with those who had poor outcomes. Multivariate logistic regression analysis was used to identify risk factors for poor clinical outcomes. Results: We analyzed 159 SAH patients; 17 patients (10.7%) had cytotoxic lesions of the corpus callosum. Patients with cytotoxic lesions of the corpus callosum were more likely to be in a severe condition (World Federation of Neurosurgical Societies grading IV-V: odds ratio [OR], 4.53; 95% confidence interval [95% CI]: 1.60–12.84; p = 0.0042) and have an intraventricular (OR, 5.98; 95% CI: 1.32–27.13; p = 0.0054) or an intraparenchymal hematoma (OR, 3.62; 95% CI: 1.25–10.45; p = 0.023). Patients with cytotoxic lesions of the corpus callosum had a greater propensity of a poor outcome 3 months after onset (modified Rankin Scale score 0–2: OR, 0.22; 95% CI: 0.07–0.66; p = 0.0043). Multivariate analysis confirmed that cytotoxic lesions of the corpus callosum increased the risk of a poor outcome (OR, 4.39; 95% CI: 1.06–18.1; p = 0.037). Discussion/Conclusions: The development of cytotoxic lesions of the corpus callosum may be related to the extent of hematomas in SAH patients. Although they are usually reversible lesions, the development of cytotoxic lesions of the corpus callosum may be a predictor of poor outcomes in SAH patients.

Application of a new hyperbaric oxygen therapy protocol in patients with arterial and venous gas embolism due to hydrogen peroxide poisoning

Hydrogen peroxide (H2O2) ingestion can cause vascular gas embolism (GE). Hyperbaric oxygen therapy (HBO2) is known to improve neurological abnormalities in patients with arterial gas embolism (AGE). Previously, HBO2 based on the U.S. Navy Table 6 diving protocol has been adopted for treating AGE and preventing the progression of portal venous GE, caused by H2O2 ingestion, to AGE. However, the indication and protocol for HBO2 have not been established for GE related to H2O2 ingestion. Herein, we describe a case in which GE caused by H2O2 ingestion was treated using HBO2 with a short protocol. A 69-year-old female patient presented with abdominal pain, vomiting, and transient loss of consciousness after ingesting 35% H2O2. Computed tomography revealed gastric wall and portal venous gas. She was administered an HBO2 protocol with 2.8-atmosphere absolute (ATA) compression for 45 minutes. This was followed by a 2.0-ATA treatment for 60 minutes with a five-minute air break, after which all gas bubbles disappeared. After HBO2 treatment, brain magnetic resonance imaging revealed focal cytotoxic edema lesions; however, the patient was discharged without additional symptoms.

Induction of aberrant agonistic behavior by a combination of serotonergic and dopaminergic manipulation in rats.

Serotonin (5-HT) and dopamine (DA) are involved in the regulation of social behaviors. However, the effects of their interactions on social behavior are not well understood. In this study, rats received a serotonergic neurotoxin injection into the raphe nuclei and/or systemic administration of L-3, 4-dihydroxyphenylalanine (L-DOPA), and their agonistic behaviors were investigated using the resident-intruder (RI) paradigm. Rats in the DA + /5-HT-group, which were administered both monoaminergic treatments, exhibited intense jump and flight responses to intruders. These behaviors were not observed in rats that received either 5-HT lesions or L-DOPA treatment only. To address the neural basis of these aberrant behaviors, we compared c-Fos immunoreactivity in the brain among the different groups. The DA + /5-HT-group had c-Fos activation in areas related to anti-predatory defensive behaviors, such as the ventromedial hypothalamic nucleus, premammillary nucleus, and periaqueductal gray. Moreover, this group had increased c-Fos expression in the ventroposterior part of the anterior olfactory nucleus (AOVP). To test the involvement of this area in the aberrant behaviors, cytotoxic lesions were performed in the AOVP prior to the monoaminergic treatments, and subsequent behaviors were examined using the RI test. The AOVP-lesioned DA + /5-HT-rats had attenuation of the aberrant behaviors. Together, these results suggest that the AOVP is involved in the generation of the aberrant defensive behaviors, and that 5-HT/DA balance is important in the regulation of social behaviors.

Cytotoxic lesion of corpus callosum in cerebral venous thrombosis\u2014a case report

BackgroundVeiled 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 presentationWhile 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.ConclusionCytotoxic 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.

Implication of Ataxia-Telangiectasia-mutated kinase in epithelium-mesenchyme transition.

Impairment of genome instability drives the development of cancer by disrupting anti-cancer barriers. Upon genotoxic insults, DNA damage responsive factors, notably ATM kinase, is crucial to protect genomic integrity while promoting cell death. Meanwhile, cytotoxic therapy-inducing DNA lesions is double-edged sword by causing cancer metastasis based on animal models and clinical observations. The underlying mechanisms for the procancer effect of cytotoxic therapies are poorly understood. Here, we report that cancer cells subjected to cytotoxic treatments elicit dramatic alteration of gene expression controlling the potential of epithelium-mesenchyme transition (EMT). Resultantly, EMT-dependent cell mobility is potently induced upon DNA damage. This stimulation of EMT is mainly Ataxia-Telangiectasia-mutated (ATM)-dependent, as the chemical inhibitor specifically inhibiting ATM kinase activity can suppress the EMT gene expression and thus cell mobility. At last, we show that cancer cells with ATM activation display increased metastatic potential in ovarian cancer tissues. Taken together, we reveal a novel role of ATM in promoting metastatic potential of cancer cells by favoring EMT gene expression.

Cytotoxic lesion of the corpus callosum in a patient with aphasic status epilepticus

A 47-year-old man with a history of aphasic seizures presented to the emergency room with a 12-hour global aphasia. Upon admission, brain MRI did not reveal acute lesions, and EEG showed sharp waves in the left frontal-temporal region. An Aphasic Status Epilepticus was diagnosed and antiepileptic treatment was initiated with adequate response. A week after the episode, a new brain MRI showed a high-signal ovoid lesion on T2-weighted and FLAIR sequences in the central part of the splenium of the corpus callosum. On diffusion-weighted images (DWI) the lesion was hyperintense with decreased apparent diffusion coefficient (ADC) values, indicating restricted diffusion consistent with a cytotoxic lesion of the corpus callosum (CLOCC). Follow-up MRI one month later showed complete image resolution. CLOCCs are secondary lesions associated with various entities in which high levels of cytokines and extracellular glutamate cause intracellular edema and reduced diffusion, a condition called cytotoxic edema, which affects vulnerable brain regions such as the splenium of the corpus callosum. In epileptic patients, CLOCCs may be due to the effect of seizures, especially prolonged ones, as well as antiepileptic treatment itself. CLOCCs are rare radiological findings and must be recognized to avoid misdiagnosis.

Cytotoxic lesion of the corpus callosum in a patient with aphasic status epilepticus

A 47-year-old man with a history of aphasic seizures presented to the emergency room with a 12-hour global aphasia. Upon admission, brain MRI did not reveal acute lesions, and EEG showed sharp waves in the left frontal-temporal region. An Aphasic Status Epilepticus was diagnosed and antiepileptic treatment was initiated with adequate response. A week after the episode, a new brain MRI showed a high-signal ovoid lesion on T2-weighted and FLAIR sequences in the central part of the splenium of the corpus callosum. On diffusion-weighted images (DWI) the lesion was hyperintense with decreased apparent diffusion coefficient (ADC) values, indicating restricted diffusion consistent with a cytotoxic lesion of the corpus callosum (CLOCC). Follow-up MRI one month later showed complete image resolution. CLOCCs are secondary lesions associated with various entities in which high levels of cytokines and extracellular glutamate cause intracellular edema and reduced diffusion, a condition called cytotoxic edema, which affects vulnerable brain regions such as the splenium of the corpus callosum. In epileptic patients, CLOCCs may be due to the effect of seizures, especially prolonged ones, as well as antiepileptic treatment itself. CLOCCs are rare radiological findings and must be recognized to avoid misdiagnosis.