Reversible restricted-diffusion lesion representing transient intramyelinic cytotoxic edema in a patient with traumatic brain injury

Case report: Re-evaluating reversibility of cytotoxic lesions of the corpus callosum

Cytotoxic lesions of the corpus callosum (CLOCC) are a clinicoradiological diagnosis, characterized by transient neurological symptoms and magnetic resonance imaging (MRI) changes in the splenium of the corpus callosum (SCC), which in most cases is completely reversible. However, the long-term pathophysiological trajectory and ultimate neurological outcomes of CLOCC remain largely unknown due to limited long-term follow-up data. We report an 11-year follow-up of a postpartum female with CLOCC, initially presenting with transient focal neurological symptoms and extensive diffusion-restricted white matter involvement including the SCC and surrounding area with diffusion restriction and low apparent diffusion coefficient values, indicative of cytotoxic edema. The edema regressed in days; over the years, she remained asymptomatic despite persistent white matter changes on MRI in the centrum semiovale. This case challenges the view of CLOCC as completely reversible and raises questions regarding the significance of lasting white matter changes. The enduring absence of neurological symptoms and stable radiological profile throughout the decade underscores the singular nature of CLOCC and the lasting, though isolated, impact on white matter. This report contributes a crucial perspective, suggesting that CLOCC may involve just an isolated episode without recurrent events or progressive neurological decline. By offering the first longitudinal analysis of a CLOCC episode with an extended follow-up of over a decade, our case enhances current knowledge about the long-term neurological and radiological landscape of this condition. It suggests a reevaluation of the conceptual understanding of CLOCC as an entirely reversible, non-relapsing disorder, highlighting the need for further research into its long-term impacts on cerebral white matter integrity.

Intramyelinic edema manifesting as central white matter diffusion restriction associated with brain contusion in pediatric patients

In traumatic brain injury, white matter diffusion restriction can be an imaging manifestation of non-hemorrhagic axonal injury. In this article, a different pattern of widespread white matter diffusion restriction associated with ipsilateral cortical damage, all noted in pediatric and young adult TBI patients, is presented. Its atypical pattern of distribution and extensive scope on imaging suggest excitotoxicity and intramyelinic edema as possible underlying mechanisms.

Case report: Reversible splenial lesion syndrome caused by diquat poisoning

Diquat (DQ), chemically known as 1,1 '-ethylene-2,2' -bipyridine, is a non-selective herbicide for leaf removal and drying. It has toxic effects on central nervous system cells, and toxic neurological lesions include axonal degeneration and pontine myelolysis. At the same time, DQ can also affect the activity of dopaminergic nerve cells through oxidative stress, causing degeneration and reducing dopamine uptake. With the increasing application of DQ in agricultural production, the clinical reports of neurotoxicity caused by acute DQ poisoning are also increasing. At present, DQ rapid-phase-related toxic encephalopathy mainly involves the pons, midbrain, basal ganglia, thalamus and other brain regions. However, this case is unusual in that the lesion mainly involved the splenium of the corpus callosum. It is also the first time to be reported.

Unusual Magnetic Resonance Imaging Findings Contrast-induced Encephalopathy following Cerebral Angiography

<p>Contrast-induced encephalopathy (CIE) following cerebral angiography has similar clinical presentations to ischemic complications of cerebral angiography. Neurologic deficits in CIE are mostly transient, but those caused by acute cerebral infarction (ACI) as ischemic complications of cerebral angiography may be permanent. Therefore, distinguishing CIE from ACI is important. Diffusion restriction on magnetic resonance imaging (MRI) implies ACI, while hyperintensity on diffusion weighted imaging (DWI) without correlation on the apparent diffusion coefficient (ADC) map implies CIE. We reported a rare case of CIE with diffusion restriction on MRI following cerebral angiography that mimicked MRI findings of ACI. The mechanism of this phenomenon remains unknown and requires further investigation.

Full Recovery From Cocaine-Induced Toxic Leukoencephalopathy: Emphasizing the Role of Neuroinflammation and Brain Edema

Toxic leukoencephalopathy (TL) is characterized by white matter disease on magnetic resonance imaging (MRI) and evidence of exposure to a neurotoxic agent. We describe a case of cocaine-induced TL in which extensive white matter disease did not preclude full recovery. A 57-year-old man with substance abuse disorder presented with a 5-day history of strange behavior. On admission, he was alert but had difficulty concentrating, psychomotor retardation, and diffuse hyperreflexia. Brain MRI revealed confluent subcortical white matter hyperintensities with restricted diffusion in some but not in other areas. Electroencephalography (EEG) showed mild diffuse slowing. Blood tests were normal except for mild hyperammonemia. Urine screen was positive for cocaine and benzodiazepine but quantitative analysis was significant only for cocaine. Prednisone 60-mg qd was initiated on day 4, tapered over a 5-day period, and discontinued on day 9. He was discharged after 3 weeks. Cognitive function returned to normal 2 weeks after discharge. Five months later, neurologic exam and EEG were normal and MRI showed near-100% resolution of white matter lesions. TL has been attributed to white matter ischemia/hypoxia resulting in demyelination/axonal injury. The clinical, EEG, and MRI findings and time course of recovery of our patient suggest that cocaine-induced inflammation/edema resulted in TL but not in ischemic/hypoxic injury. While inflammation/edema may have regressed when cocaine was discontinued, we cannot exclude a role for prednisone in protecting the patient from the ischemic/hypoxic sequelae of inflammation/edema. MRI is indispensable for diagnosing TL but EEG may provide additional useful diagnostic and prognostic information.

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.

Clinical trials in traumatic brain injury: cellular therapy and outcome measures

Clinical trials for traumatic brain injury (TBI) have not successfully produced a new therapeutic for neuroprotection or neurorestoration, despite multiple attempts. Stem cell-based therapies and/or cellular therapies have been developed over the past 20 years such that clinical trials are now in Phase II and III stages for neurologic diseases such as TBI and stroke. Many of the vexing issues from past clinical failures still exist today, namely, preclinical data that may not translate to clinical trial because of design and injury heterogeneity that poorly stratifies enrolled patients. Recognition of these problems has led us to advocate for outcome measures that are clinically meaningful, but do not represent a global functional "score." Specifically, we seek to measure those early physiologically relevant outcomes (intracranial pressure, edema, and therapeutic intensity) and later structural outcomes in regions of interest that are linked to putative mechanisms of action of cell based therapies. Early approval of therapeutics that are successful by these metrics would then allow further access to treatments that could be further tested via patient registries and other surveillance for ultimate adoption. Continuing to do the same thing with each iterative trial will assure the same results.

Respiratory syncytial virus-associated seizures in Korean children, 2011-2016

Purpose

Respiratory syncytial virus (RSV) infection can cause various neurological complications. This study aimed to investigate the RSV-associated neurologic manifestations that present with seizures.

Methods

We retrospectively reviewed the medical records of patients aged less than 15 years with laboratory-confirmed RSV infections and seizures between January 2011 and December 2016 in a regional hospital in South Korea.

Results

During this period, 1,193 patients with laboratory-confirmed RSV infection were identified. Of these, 35 (35 of 1,193, 2.93%; boys, 19; girls, 16; mean age: 20.8±16.6 months) presented with seizure. Febrile seizure was the most common diagnosis (27 of 35, 77.1%); simple febrile seizures in 13 patients (13 of 27, 48.1%) and complex febrile seizures in 14 (14 of 27, 51.9%). Afebrile seizures without meningitis or encephalopathy were observed in 5 patients (5 of 35, 14.3%), seizures with meningitis in 2 (2 of 35, 5.7%), and seizure with encephalopathy in 1 (1 of 35, 2.9%) patient. Lower respiratory symptoms were not observed in 8 patients. In a patient with encephalopathy, brain diffusion-weighted magnetic resonance imaging revealed transient changes in white matter, suggesting cytotoxic edema as the mechanism underlying encephalopathy. Most patients recovered with general management, and progression to epilepsy was noted in only 1 patient.

Conclusion

Although febrile seizures are the most common type of seizure associated with RSV infection, the proportion of patients with complex febrile seizures was higher than that of those with general febrile seizures. Transient cytotoxic edema may be a pathogenic mechanism in RSV-related encephalopathy with seizures.

Stroke-like migraine attacks after radiation therapy: A misnomer?

OBJECTIVE

To understand the frequency of electrographic and clinical seizures in patients with stroke-like migraine attacks after radiation therapy (SMART), and determine whether SMART warrants comprehensive electroencephalographic (EEG) monitoring and aggressive seizure management.

METHODS

We searched our magnetic resonance brain imaging report database for all patients between January 2013 and December 2015 for suspected SMART syndrome. Clinical inclusion criteria were further applied as follows: inpatient adults (>18 years of age) with history of cranial radiation presenting with acute neurologic deficits as primary admission reason who lacked evidence of recurrent or new brain malignancy, stroke, or infectious agents in cerebrospinal fluid. Six patients were identified. All 6 patients underwent prolonged video EEG monitoring as part of our standard protocol.

RESULTS

All patients but 1 were found to have multiple or prolonged electrographic seizures consistent with status epilepticus during video EEG monitoring. Their neurological deficit and/or mental status change improved in parallel with resolution of the seizure activity.

SIGNIFICANCE

SMART is likely a misnomer that underestimates the significance of seizures and status epilepticus in the pathophysiology and clinical presentation of the syndrome. Systematic continuous EEG monitoring and appropriate seizure management is warranted to reduce symptom duration and optimize clinical outcome.

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.

Complete Reversal of Diffusion Restriction after Treatment of Traumatic Carotid-Cavernous Fistula

A 15-year-old man presented with stupor following a motorcycle traffic accident. The patient was diagnosed with a traumatic left carotid cavernous fistula (CCF) with pseudoaneurysm of the left internal carotid artery. Brain magnetic resonance imaging (MRI) showed transiently restricted diffusion in the left centrum semiovale white matter and lower temporo-occipital area extending to the splenium of the corpus callosum, with high signal intensity on diffusion-weighted imaging. On the 35th day of admission, the patient had complete neurological recovery and a follow-up brain MRI revealed complete resolution of the lesions in the left centrum semiovale and splenium of the corpus callosum. These clinical and radiological features are highly suggestive of complete reversal of diffusion restriction after successful embolization of traumatic CCF.