Transient Focal Lesion of Corpus Callosum in Epilepsy: A Case Report

INTRODUCTION

Transient focal lesions in the splenial area of corpus callosum (SCC) are nowadays being detected in a wide variety of clinical conditions including seizures, AED therapy or withdrawal, metabolic disturbances, cerebrovascular diseases, infections, malignancy, drugs and toxins, eclampsia, alcohol use (Marchiafava-bignami disease), high-altitude cerebral edema, trauma, etc. due to the increasing use of MRI. Recently several terms like transient lesions of the splenium of the corpus callosum, cytotoxic lesions of the corpus callosum (CLOCCs), mild encephalopathy with a reversible isolated SCC lesion (MERS), reversible splenial lesion syndrome (RESLES)¹ have been described in different medical conditions which usually manifest with neurological symptoms, delirious behavior and seizures. Reversible lesions of the corpus callosum are not always associated with a favorable outcome and the prognosis has been observed to depend largely on the underlying etiology. However, in regard to epilepsy or AED induced lesions, the prognosis has been reported to be much better.²

DISCUSSION

In epilepsy, transient isolated SCC lesions are seen due to the seizures themselves without medication or with the use of antiepileptic medications, even sudden abrupt discontinuation or reduction or withdrawal of AED in both seizure disorder or without seizure disorder.³ Among all the AEDs CBZ has mostly been found to be associated with transient splenial lesions (TSL) in studies. Though there is still no clear cut pathophysiology, the most accepted mechanism in AED has been its effect on the fluid balance system by arginine vasopressin system (AVP levels) causing cytotoxic edema, while other mechanisms are believed to lead to these similar lesions in other medical conditions. Focal splenial lesions in other medical conditions or causes have also been found to present with confusional and psychiatric manifestations.

These lesions can only be appreciated on MRI. Small well-defined oval-shaped lesions in the midline are typically seen in seizures or AED discontinuation cases, while bigger and extensive lesions are indicative of other pathophysiology.⁴

CONCLUSION

Based on the patient’s clinical course of frequent seizures, the sudden withdrawal of AEDs especially CBZ, MRI findings of a classical lesion seen in epileptic patients, and recovery within weeks are the favorable explanations for the transient cytotoxic lesion seen in the corpus callosum. Thorough awareness and familiarity with the condition can prevent misdiagnosis while dealing with other conditions that present with similar MRI findings and presentation. The use of antiepileptics especially CBZ should be highly suspected in such cases and at the same time avoid non-essential diagnostic techniques. Also, careful tapering should be considered while dealing with AEDs.

ORCID

Jubilee Evangeline Darnei https://orcid.org/0000-0002-2882-3063

REFERENCES

1. Lu PL, Hodes JF, Zheng X, et al. Reversible splenial lesion syndrome with some novel causes and clinical manifestations. Intern Med 2020; 59(20):2471–2480.DOI: 10.2169/internalmedicine.4516-20.

2. Xu Z, Zhou Z, Jang W, et al. Reversible splenial lesion syndrome with mental disorders as only manifestation. BMC Neurology 2021; 21(1):1–7.DOI: https://doi.org/10.1186/s12883-021-02391-6.

3. Garcia‐Monco JC, Cortina IE, Ferreira E, et al. Reversible splenial lesion syndrome (RESLES): what’s in a name?. J Neuroimaging 2011;21(2):e1–e4. DOI: 10.1111/j.1552-6569.2008.00279.x.

4. Anneken K, Evers S, Mohammadi S, et al. Transient lesion in the splenium related to antiepileptic drug: Case report and new pathophysiological insights. Seizure 2008;17(7):654–657. DOI: 10.1016/j.seizure.2008.01.004.