Diffusion-weighted magnetic resonance imaging in early stage of 5-fluorouracil-induced leukoencephalopathy

5-Fluorouracil-induced leukoencephalopathy

ABSTRACT

The incidence of 5-Fluorouracil (5FU)- induced leukoencephalopathy is <5% among the patients treated with this agent. It may present with disorientation, confusion, agitation, seizure, and coma. It should be suspected when patients present with any of these symptoms during or immediately after 5FU chemotherapy. Early detection of drug-induced leukoencephalopathy is important as the clinical symptoms can be reversed by early discontinuation of the drug. Therefore, clinicians should be aware of the possibility of this adverse neurologic effect of 5FU. We describe the case of a 35-year-old female with carcinoma esophagus with 5FU-induced leukoencephalopathy.

Reversible splenial lesion syndrome with mental disorders as only manifestation

Background

Reversible splenial lesion syndrome (RESLES) was reported to be associated with variable entities. However, much less is known about the cases in which the mental disorders act as the only manifestation.

Method

Total ten patients of RESLES were obtained in this retrospective study from Shenzhen Kangning Hospital. T1-fluid attenuated inversion recovery (T1-FLAIR), T2-weighted images, T2-FLAIR, diffusion-weighted images and apparent diffusion coefficient map were performed on all the patients. Clinical manifestations, laboratory examination results, magnetic resonance imaging (MRI) findings, treatments and outcomes were analyzed.

Result

All patients showed different mental disorders as the only manifestation. There were two cases of alcohol abuse, one of Asperger’s syndrome with malnutrition, one of infection and one of invasive pituitary adenoma. The other cases were diagnosis as major depressive disorder, dissociative and conversion disorders, undifferentiated somatoform disorder, unspecified psychosis and bipolar disorder, respectively. Three patients were completely recovered while the clinical symptoms of rest seven patients partially recovered at the follow-up three months later. Oval-shaped lesion centered on the splenial of corpus callosum (SCC) was observed in all patients using MRI. The lesions of SCC of all patients were completely resolved within five weeks.

Conclusions

We found that RESLES might only showed mental symptoms. On the one hand, for the patients with acute mental disorders, clinicians should be alert to the possibility of RESLES caused by physical disease. On the other hand, we suggest that mental disorder might be a precipitating factor of RESLES.

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.

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.

Reversible splenial lesions presenting in conjunction with febrile illness: a case series and literature review

Transient restricted diffusion and increased T2 signal intensity within the splenium of the corpus callosum is an increasingly recognized albeit uncommon imaging feature in the setting of acute encephalitis and antecedent viral illness. This review will discuss three index cases obtained from an institutional databank. Additionally, the current understanding of the underlying neurophysiologic pathogenesis will be discussed together with differential clinical and imaging diagnostic considerations, treatment options, and outcome metrics.

Cytotoxic Lesions of the Corpus Callosum That Show Restricted Diffusion: Mechanisms, Causes, and Manifestations

Cytotoxic lesions of the corpus callosum (CLOCCs) are secondary lesions associated with various entities. CLOCCs have been found in association with drug therapy, malignancy, infection, subarachnoid hemorrhage, metabolic disorders, trauma, and other entities. In all of these conditions, cell-cytokine interactions lead to markedly increased levels of cytokines and extracellular glutamate. Ultimately, this cascade can lead to dysfunction of the callosal neurons and microglia. Cytotoxic edema develops as water becomes trapped in these cells. On diffusion-weighted magnetic resonance (MR) images, CLOCCs manifest as areas of low diffusion. CLOCCs lack enhancement on contrast material-enhanced images, tend to be midline, and are relatively symmetric. The involvement of the corpus callosum typically shows one of three patterns: (a) a small round or oval lesion located in the center of the splenium, (b) a lesion centered in the splenium but extending through the callosal fibers laterally into the adjacent white matter, or (c) a lesion centered posteriorly but extending into the anterior corpus callosum. CLOCCs are frequently but not invariably reversible. Their pathologic mechanisms are discussed, the typical MR imaging findings are described, and typical cases of CLOCCs are presented. Although CLOCCs are nonspecific with regard to the underlying cause, additional imaging findings and the clinical findings can aid in making a specific diagnosis. Radiologists should be familiar with the imaging appearance of CLOCCs to avoid a misdiagnosis of ischemia. When CLOCCs are found, the underlying cause of the lesion should be sought and addressed. ^©RSNA, 2017 An earlier incorrect version of this article appeared online. This article was corrected on February 13, 2017.

Redox biology in normal cells and cancer: restoring function of the redox/Fyn/c-Cbl pathway in cancer cells offers new approaches to cancer treatment

This review discusses a unique discovery path starting with novel findings on redox regulation of precursor cell and signaling pathway function and identification of a new mechanism by which relatively small changes in redox status can control entire signaling networks that regulate self-renewal, differentiation, and survival. The pathway central to this work, the redox/Fyn/c-Cbl (RFC) pathway, converts small increases in oxidative status to pan-activation of the c-Cbl ubiquitin ligase, which controls multiple receptors and other proteins of central importance in precursor cell and cancer cell function. Integration of work on the RFC pathway with attempts to understand how treatment with systemic chemotherapy causes neurological problems led to the discovery that glioblastomas (GBMs) and basal-like breast cancers (BLBCs) inhibit c-Cbl function through altered utilization of the cytoskeletal regulators Cool-1/βpix and Cdc42, respectively. Inhibition of these proteins to restore normal c-Cbl function suppresses cancer cell division, increases sensitivity to chemotherapy, disrupts tumor-initiating cell (TIC) activity in GBMs and BLBCs, controls multiple critical TIC regulators, and also allows targeting of non-TICs. Moreover, these manipulations do not increase chemosensitivity or suppress division of nontransformed cells. Restoration of normal c-Cbl function also allows more effective harnessing of estrogen receptor-α (ERα)-independent activities of tamoxifen to activate the RFC pathway and target ERα-negative cancer cells. Our work thus provides a discovery strategy that reveals mechanisms and therapeutic targets that cannot be deduced by standard genetics analyses, which fail to reveal the metabolic information, isoform shifts, protein activation, protein complexes, and protein degradation critical to our discoveries.

Toxic leukoencephalopathies, including drug, medication, environmental, and radiation-induced encephalopathic syndromes

Toxic leukoencephalopathies can be secondary to the exposure to a wide variety of exogenous agents, including cranial irradiation, chemotherapy, antiepileptic agents, drugs of abuse, and environmental toxins. There is no typical clinical picture, and patients can present with a wide array of signs and symptoms. Involvement of white matter is a key finding in this scenario, although in some circumstances other high metabolic areas of the central nervous system can also be affected. Magnetic resonance (MR) imaging usually discloses bilateral and symmetric white matter areas of hyperintense signal on T2-weighted and fluid-attenuated inversion recovery images, and signs of restricted diffusion are associated in the acute stage. In most cases, the changes are reversible, especially with prompt recognition of the disease and discontinuation of the noxious agent. Either the MR or clinical features may be similar to several nontoxic entities, such as demyelinating diseases, leukodystrophies, hepatic encephalopathy, vascular disease, hypoxic-ischemic states, and others. A high index of suspicion should be maintained whenever a patient presents recent onset of neurologic deficit, searching the risk of exposure to a neurotoxic agent. Getting to know the most frequent MR appearances and mechanisms of action of causative agents may help to make an early diagnosis and begin therapy, improving outcome. In this review, some of the most important causes of leukoencephalopathies are presented; as well as other 2 related conditions: strokelike migraine attacks after radiation therapy syndrome and reversible splenial lesions.

Effects of 5-FU

5-fluorouracil (5-FU) is a chemotherapeutical agent used to treat cancers including breast and colorectal. Working as an antimetabolite to prevent cell proliferation, it primarily inhibits the enzyme thymidylate synthase blocking the thymidine formation required for DNA synthesis. Although having a relatively short half-life (< 30 mins) it readily enters the brain by passive diffusion. Clinically, it is used both as a single agent or in combination with other chemotherapies and has been associated with the long-term side effects of cognitive impairment, known as "chemo brain" or "chemo fog" These accounts have come primarily from patients undergoing treatment for breast cancer who report symptoms including confusion and memory impairment, which can last for months to years. Psychometric studies of patients have suffered from confounding variables, which has led to the use of rodent models to assess the cognitive effects of this drug. Researchers have used behavioral and physiological tests including the Morris water maze, novel object location/recognition tests, shock motivated T-maze, sensory gating and conditioning, to investigate the effect of this drug on cognition. The variety of cognitive tests and the difference in dosing and administration of 5-FU has led to varied results, possibly due to the different brain regions associated with each test and the subtlety of the drug's effect, but overall these studies indicates that 5-FU has a negative effect on memory, executive function and sensory gating. 5-FU has also been demonstrated to have biochemical and structural changes on specific regions of the brain. Evidence shows it can induce apoptosis and depress cell proliferation in the neurogenic regions of the adult brain including the sub granular zone (SGZ) within the hippocampus and in oligodendrocyte precursor populations within white matter tracts. Furthermore, investigations indicate levels ofdoublecortin, a marker for newly formed neurons and brain derived neurotrophic factor, a cell survival modulator, are also reduced by 5-FU in the SGZ. Thus, 5-FU appears to have a lasting negative impact on cognition and to affect cellular and biochemical markers in various brain regions. Further work is needed to understand the exact mechanisms involved and to devise strategies for the prevention or recovery from these symptoms.

Acute toxic leukoencephalopathy: potential for reversibility clinically and on MRI with diffusion-weighted and FLAIR imaging

OBJECTIVE

Toxic leukoencephalopathy may present acutely or subacutely with symmetrically reduced diffusion in the periventricular and supraventricular white matter, hereafter referred to as periventricular white matter. This entity may reverse both on imaging and clinically. However, a gathering together of the heterogeneous causes of this disorder as seen on MRI with diffusion-weighted imaging (DWI) and an analysis of their likelihood to reverse has not yet been performed. Our goals were to gather causes of acute or subacute toxic leukoencephalopathy that can present with reduced diffusion of periventricular white matter in order to promote recognition of this entity, to evaluate whether DWI with apparent diffusion coefficient (ADC) values can predict the extent of chronic FLAIR abnormality (imaging reversibility), and to evaluate whether DWI can predict the clinical outcome (clinical reversibility).

MATERIALS AND METHODS

Two neuroradiologists retrospectively reviewed the MRI examinations of 39 patients with acute symptoms and reduced diffusion of periventricular white matter. The reviewers then scored the extent of abnormality on DWI and FLAIR. ADC ratios of affected white matter versus the unaffected periventricular white matter were obtained. Each patient's clinical records were reviewed to determine the cause and clinical outcome. Histology findings were available in three patients. Correlations were calculated between the initial MRI markers and both the clinical course and the follow-up extent on FLAIR using Spearman's correlation coefficient.

RESULTS

Of the initial 39 patients, seven were excluded because of a nontoxic cause (hypoxic-ischemic encephalopathy [HIE] or congenital genetic disorders) or because of technical errors. In the remaining 32 patients, no correlation was noted between any of the initial MRI markers (percentage of ADC reduction, DWI extent, or FLAIR extent) with the clinical outcome. Three patients had histologic correlation. However, moderate correlation was seen between the extent of abnormality on initial FLAIR and the extent on follow-up FLAIR (r = 0.441, p = 0.047). Of the 13 patients who underwent repeat MRI at 21 days or longer, the reduced diffusion resolved in all but one. Significant differences were noted between ADC values in affected white matter versus unaffected periventricular white matter on initial (p < 0.0001) but not on follow-up MRI (p = 0.13), and in affected white matter on initial versus follow-up (p = 0.0014) in those individuals who underwent repeat imaging on the same magnet (n = 9), confirming resolution of the DWI abnormalities.

CONCLUSION

Acute toxic leukoencephalopathy with reduced diffusion may be clinically reversible and radiologically reversible on DWI, and may also be reversible, but to a lesser degree, on FLAIR MRI. None of the imaging markers measured in this study appears to correlate with clinical outcome, which underscores the necessity for prompt recognition of this entity. Alerting the clinician to this potentially reversible syndrome can facilitate treatment and removal of the offending agent in the early stages.

Systemic 5-fluorouracil treatment causes a syndrome of delayed myelin destruction in the central nervous system

BACKGROUND

Cancer treatment with a variety of chemotherapeutic agents often is associated with delayed adverse neurological consequences. Despite their clinical importance, almost nothing is known about the basis for such effects. It is not even known whether the occurrence of delayed adverse effects requires exposure to multiple chemotherapeutic agents, the presence of both chemotherapeutic agents and the body's own response to cancer, prolonged damage to the blood-brain barrier, inflammation or other such changes. Nor are there any animal models that could enable the study of this important problem.

RESULTS

We found that clinically relevant concentrations of 5-fluorouracil (5-FU; a widely used chemotherapeutic agent) were toxic for both central nervous system (CNS) progenitor cells and non-dividing oligodendrocytes in vitro and in vivo. Short-term systemic administration of 5-FU caused both acute CNS damage and a syndrome of progressively worsening delayed damage to myelinated tracts of the CNS associated with altered transcriptional regulation in oligodendrocytes and extensive myelin pathology. Functional analysis also provided the first demonstration of delayed effects of chemotherapy on the latency of impulse conduction in the auditory system, offering the possibility of non-invasive analysis of myelin damage associated with cancer treatment.

CONCLUSIONS

Our studies demonstrate that systemic treatment with a single chemotherapeutic agent, 5-FU, is sufficient to cause a syndrome of delayed CNS damage and provide the first animal model of delayed damage to white-matter tracts of individuals treated with systemic chemotherapy. Unlike that caused by local irradiation, the degeneration caused by 5-FU treatment did not correlate with either chronic inflammation or extensive vascular damage and appears to represent a new class of delayed degenerative damage in the CNS.

A case of manic episode during treatment with 5-fluorouracil, epirubicin and cyclophosphamide for breast cancer

A 41-year-old woman with breast cancer developed a manic episode while being treated with a 5-fluorouracil-epirubicin-cyclophosphamide combination (most likely caused by the first drug). Chemotherapy was discontinued, and antipsychotic treatment with haloperidol and olanzapine was instituted. She recovered after 10 days. Normal computerized tomography (CT) scans and neurological examinations were consistent with the absence of neurological symptoms on physical exam.

Reversible splenial lesion with restricted diffusion in a wide spectrum of diseases and conditions

OBJECTIVE

Reversible lesion in the central area of the splenium of the corpus callosum (SCC) is a unique phenomenon occurring particularly in patients with encephalitis or encephalopathy and in patients receiving antiepileptic drugs (AED). We report MR imaging findings, clinical courses, and outcomes in eight patients with various diseases and conditions.

MATERIALS AND METHODS

Eight patients with a reversible SCC lesion with transiently restricted diffusion were reviewed retrospectively. Diseases and conditions that were associated with a reversible lesion included epilepsy receiving AED (n=1), seizure from eclampsia receiving AED (n=1), mild infectious encephalitis (n=2), hypernatremia resulting in osmotic myelinolysis (n=1), and neoplasm (n=3) such as acute lymphocytic leukemia, spinal meningeal melanocytoma, and esophageal cancer. We evaluated MR imaging findings and clinical findings.

RESULTS

Seven patients had isolated SCC lesions; one patient with osmotic myelinolysis showed additional parenchymal lesions. The reversible SCC lesion shape was oval (n=6) or extended (n=2). The mean apparent diffusion coefficient value of the splenial lesion was 0.40+/-0.16 x 10-3 mm2/s, ranging from 0.22 to 0.64 x 10-3 mm2/s. In a patient with osmotic myelinolysis, additional white matter lesions, shown as restricted diffusion, were revealed as not reversible on follow-up MR imaging. Neurological courses and outcomes were good in seven patients with isolated SCC lesions, but poor in one with osmotic myelinolysis.

CONCLUSION

Reversible SCC lesion with restricted diffusion is apparent in a wide spectrum of diseases and conditions. Neurological courses and outcomes are good, particularly in patients with isolated SCC lesions. Knowledge of MR imaging findings and the associated spectrum of diseases and conditions might prevent unnecessary invasive examinations and treatments.

Reversible findings of restricted diffusion in 5-flourouracil neurotoxicity

A 35-year-old woman presented with neurotoxicity correlated to an i.v. regimen of 5-fluorouracil as episodes of acute confusional state and abnormalities of symmetrically restricted diffusion in the periventricular white matter and corpus callosum. On discontinuing the medication, the areas of severely restricted diffusion had entirely resolved, with minimal residual T2 signal abnormality. In this case, immediate discontinuation of the chemotherapeutic agent apparently reversed the patient's symptoms and findings on MRI. The scant information available in the published literature regarding this phenomenon is reviewed with regard to 5-fluorouracil.

Transient splenium lesions in presurgical epilepsy patients: incidence and pathogenesis

INTRODUCTION

Transient splenium corporis callosi (SCC) lesions are related to rapid reduction of antiepileptic drugs (AEDs). The range of substances with predilection for SCC changes, their pathophysiology and their occurrence are still unknown.

METHODS

In a prospective 2-year study an epilepsy-dedicated MRI protocol supplemented by DWI and ADC maps was performed after AED withdrawal for diagnostic seizure provocation in all patients with pharmacoresistant seizures locally admitted to the Department of Epileptology.

RESULTS

Of 891 presurgical epilepsy patients, 6 (0.7%) had SCC lesions with cytotoxic edema on DWI. Carbamazepine combined with other AEDs was administered in five of those patients. In the study period we observed identical lesions in a schizophrenic patient treated with olanzapine and citalopram, in a patient with oropharyngeal carcinoma treated with alkylating agents, and in a hypernatremic patient following neurohypophyseal granular cell tumor surgery.

CONCLUSION

Transient SCC lesions are related to rapid AED reduction but may occur in similar conditions with fluid balance alterations. We contribute further clinical data in this field to better classify the pharmaceuticals that are prone to the described cerebral cytotoxic side effects in the SCC and to clarify their incidence among presurgical epilepsy patients.