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

Abstract

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.

Rapid discontinuation of sodium channel–blocking antiseizure drugs evokes focal edema in the splenium corporis callosi: A matched case‐control study

“…The reason for the apparent site of predilection of intramyelinic edema in the splenium is currently unknown. Differing fiber characteristics within the corpus callosum have been proposed as an explanation . When evaluating all 325 patients with quantifiable MRI ADC maps, we found a weak correlation between the relative reduction of the scASD dose‐reduction rate and diffusion restriction in the splenium corporis callosi.…”

Reversible lesion in the splenium of the corpus callosum

“…It is also often used to diagnose acute cerebral infarction that results in cytotoxic edema that is considered to lead to an irreversible lesion and cellular death (Baehring & Fulbright, ). ADC maps display only the diffusion component; the SCC appears hypointense, and the low‐signal area in ADC generally indicates cytotoxic edema secondary to ischemia, which could lead to neurological sequelae (Starkey et al, ). However, in these disease conditions, the reversible lesions in the SCC usually disappear completely without sequelae.…”

“…The exact pathophysiological mechanism underlying the reversible lesion in the SCC is still obscure. There are several hypotheses about entities such as intramyelinic edema (Tada et al, ), inflammatory infiltrates (Tada et al, ), hyponatemia (Takanashi et al, ), oxidative stress (Miyata et al, ), neuroaxonal damage (Motobayashi et al, ), autoimmune processes (Kaminski & Prüss, ), and cytotoxic edema (Garcia‐Monco et al, ; Starkey et al, ). Cytotoxic edema is characterized by the swelling of the cellular elements in neurons and glial cells with a subsequent reduction in the extracellular space in the gray matter.…”

“…In addition to infection, MERS has also been reported to be associated with epilepsy and the use of antiepileptic drugs (Maeda et al, 2003;Mirsattari, Lee, Jones, & Blume, 2003). Extant literature has reported the other potential causes including substance withdrawal, metabolic disturbance, drug-related toxicity, malignancies, cerebrovascular diseases, traumatic brain injury, status migrainosus, and high-altitude disease (altitude sickness) (Al Brashdi & Albayram, 2015;Bin & Lee, 2011;Garcia-Monco et al, 2011;Kallenberg et al, 2007;Kim & Gean, 2011;Maeda et al, 2006;Park et al, 2017;Renard, Bonafe, & Heroum, 2007;Samanta, 2015;Starkey, Kobayashi, Numaguchi, & Moritani, 2017;Takanashi et al, 2009;Takayama, Kobayashi, Sugishita, & Mihara, 2000;Tha et al, 2002;Yamaguchi et al, 2019). A listing is provided in Table identified the etiologies for 30 cases including cerebral infarction (50%), trauma (13.3%), tumor (10%), alcohol abuse (6.7%), seizure (6.7%), heat stroke (3.3%), multiple sclerosis (3.3%), drug intoxication (3.3%), and panhypopituitarism (3.3%).…”

Reversible Lesion of the Corpus Callosum in a Patient With Migraine With Aura: A Case Study

“…This rare clinical‐radiological phenomenon has been referred to in the literature by various names in the past, including reversible splenial lesion syndrome (RESLES), or, if associated with encephalopathy, as mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) . More recently, the lesions have been called cytotoxic lesions of the corpus callosum (CLOCCs) . They are characterized by an abnormality of the splenium of the CC on MRI with subsequent resolution of the lesion on follow‐up imaging.…”