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Transient MR signal changes in patients with generalized tonicoclonic seizure or status epilepticus: periictal
1Department of Diagnostic Radiology, the Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, South Korea.
Background And Purpose:
Our purpose was to investigate transient MR signal changes on periictal MR images of patients with generalized tonicoclonic seizure or status epilepticus and to evaluate the clinical significance of these findings for differential diagnosis and understanding of the pathophysiology of seizure-induced brain changes.
Methods:
Eight patients with MR images that were obtained within 3 days after the onset of generalized tonicoclonic seizure or status epilepticus and that showed seizure-related MR signal changes had their records retrospectively reviewed. T1- and T2-weighted images were obtained of all eight patients. Additional diffusion-weighted images were obtained of five patients during initial examination. After adequate control of the seizure was achieved, follow-up MR imaging was performed. We evaluated the signal changes, location of the lesions, and degree of contrast enhancement on T1- and T2-weighted images and the signal change and apparent diffusion coefficient (ADC) on diffusion-weighted images. We also compared the signal changes of the initial MR images to those of the follow-up MR images.
Results:
The initial MR images revealed focally increased T2 signal intensity, swelling, and increased volume of the involved cortical gyrus in all eight patients. The lesions were located in the cortical gray matter or subcortical white matter in seven patients and at the right hippocampus in one. T1-weighted images showed decreased signal intensity at exactly the same location (n = 6) and gyral contrast enhancement (n = 4). Diffusion-weighted images revealed increased signal intensity at the same location and focally reduced ADC. The ADC values were reduced by 6% to 28% compared with either the normal structure opposite the lesion or normal control. Follow-up MR imaging revealed the complete resolution of the abnormal T2 signal change and swelling in five patients, whereas resolution of the swelling with residual increased T2 signal intensity at the ipsilateral hippocampus was observed in the other two patients. For one of the two patients, hippocampal sclerosis was diagnosed. For the remaining one patient, newly developed increased T2 signal intensity was shown.
Conclusion:
The MR signal changes that occur after generalized tonicoclonic seizure or status epilepticus are transient increase of signal intensity and swelling at the cortical gray matter, subcortical white matter, or hippocampus on periictal T2-weighted and diffusion-weighted images. These findings reflect transient cytotoxic and vasogenic edema induced by seizure. The reversibility and typical location of lesions can help exclude the epileptogenic structural lesions.
Insights
Transient MRI signal changes, including swelling and increased T2 intensity, are observed after generalized tonic-clonic seizures. These reversible findings in the brain help differentiate seizure-induced changes from permanent structural lesions.
Area of Science:
- Neurology
- Radiology
- Neuroimaging
Background:
- Generalized tonic-clonic seizure (GTCS) and status epilepticus (SE) can cause transient brain changes.
- Understanding these periictal changes is crucial for differential diagnosis and pathophysiology.
Purpose of the Study:
- To investigate transient MR signal changes following GTCS or SE.
- To evaluate the clinical significance of these findings for diagnosis and understanding seizure pathophysiology.
Main Methods:
- Retrospective review of MR images from eight patients within 3 days of GTCS or SE.
- Analysis of T1-weighted, T2-weighted, and diffusion-weighted images, including apparent diffusion coefficient (ADC) values.
- Comparison of initial and follow-up MR imaging after seizure control.
Main Results:
- Initial MRIs showed increased T2 signal intensity, swelling, and volume in affected cortical gray matter or subcortical white matter.
- Diffusion-weighted imaging revealed increased signal intensity and reduced ADC values.
- Follow-up MRIs demonstrated complete resolution in most patients, with some residual changes or new findings in others.
Conclusions:
- Periictal MR findings after GTCS or SE include transient T2 signal increase and swelling in the brain.
- These changes reflect temporary cytotoxic and vasogenic edema.
- The transient nature and typical locations of these lesions aid in excluding permanent epileptogenic structural abnormalities.