Epilepsy Transient Cortical Abnormalities on Magnetic Resonance Imaging after Status Epilepticus: Case Report Aaron A. Cohen-Gadol, M.D.,* Jeffrey W. Britton, M.D.,† Gregory A. Worrell, M.D.,† and Fredric B. Meyer, M.D.* *Departments of Neurologic Surgery and †Neurology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota Cohen-Gadol AA, Britton JW, Worrell GA, Meyer FB. Transient cortical abnormalities on magnetic resonance imaging after status epilepticus: case report. Surg Neurol 2004;61:479 – 82. INTRODUCTION Transient neuroimaging findings associated with seizure activity have received relatively little attention in the neurosurgical literature. These abnormalities may mimick neoplastic or ischemic changes on magnetic resonance imaging (MRI), possibly leading to additional studies and surgical treatment. CASE DESCRIPTION A 17-year-old right-handed male was transferred to emergency room in status epilepticus. A MRI obtained 5 months before admission was negative. On the day of admission, he had multiple intermittent upper-left extremity partial seizures and prolonged secondary generalized seizures. An electroencephalogram (EEG) showed frequent epileptiform discharges over the right hemisphere posteriorly. A MRI study performed 2 days after admission revealed non-hemorrhagic abnormalities involving the right occipital region that were hyperintense on fluid-attenuated inversion recovery (FLAIR) and T2 weighted sequences. The apparent diffusion coefficient map was unremarkable. Follow-up MRIs, 3 and 11 months after admission, showed complete resolution of these lesions. CONCLUSION Imaging findings after status epilepticus may raise suspicion of ischemic or neoplastic lesions. These findings may be reversible. Further follow-up imaging may prevent unnecessary intervention. © 2004 Elsevier Inc. All rights reserved. KEY WORDS Epilepsy, status epilepticus, magnetic resonance imaging, transient, cortical abnormality. Address reprint requests to: Aaron A. Cohen-Gadol, M.D., Department of Neurologic Surgery, Joseph 1–229, Saint Mary’s Hospital, 1216 Second Street SW, Rochester, MN 55905. Received January 31, 2003; accepted June 23, 2003. © 2004 Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010 –1710 ransient computerized tomography (CT) and magnetic resonance imaging (MRI) abnormalities may occur after a seizure, most often following status epilepticus [2,4,9,10]. It is important to recognize that seizures can produce transient MRI abnormalities to avoid unnecessary neurosurgical procedures, for example, brain biopsy or invasive cerebral vascular studies. Complementary noninvasive neuroimaging studies may help elucidate the nature of these abnormalities. T Case Report A 17-year-old right-handed male was transferred to the emergency room in status epilepticus. He had a history of febrile seizures and a partial seizure disorder since age 10. He had no history of developmental delay, meningitis, encephalitis, or significant head injury. A MRI obtained 5 months before admission was negative. His typical seizures involved turning of the head to the left, left arm extension, and secondary generalized seizures. He was previously treated successfully with carbamazepine (500 mg twice a day), but was unable to take it the day before admission because of a flu-like illness. On the day of admission, he had multiple intermittent upper-left extremity partial seizures and prolonged secondary generalized seizures. He was admitted, intubated, and was started on lorazepam, fosphenytoin, phenobarbital, levetiracetam, and continued on carbamazepine. Upon discontinuation of his sedation, his neurologic examination was significant for left-sided apraxia and a left homonymous hemianopia. He continued to have simple partial motor seizures involving the distal left upper extremity. 0090-3019/04/$–see front matter doi:10.1016/S0090-3019(03)00540-8 480 Surg Neurol 2004;61:479 – 82 Cohen-Gadol et al Axial MRI T2-weighted (A) and FLAIR (B) sequences reveal gyriform cortical hyperintensities in the right occipital region. Contrast-enhanced images (C) reveal prominent right occipital vessels. 1 An electroencephalogram (EEG) showed frequent epileptiform discharges over the right hemisphere posteriorly. A MRI study performed 2 days after admission revealed non-hemorrhagic abnormalities involving the right occipital region that were hyperintense on fluid-attenuated inversion recovery (FLAIR) and T2 weighted sequences (Figure 1 A, B). Contrast-enhanced images revealed prominent right occipital vessels (Figure 1C). Diffusion weighted images showed hyperintensity in the similar region (Figure 2 A), however; the apparent diffusion coefficient (ADC) map was unremarkable (Figure 2B). Follow-up MRIs, 3 and 11 months (Figure 3) after admission, showed complete resolution of these lesions. He continued having intermittent visual auras in the left visual field followed by left upper extremity myoclonic jerks. His left homonymous visual field deficit remained unchanged. Transient Cortical Lesion 2 Surg Neurol 481 2004;61:479 – 82 A diffusion-weighted axial MRI image (A) reveals hyperintensities in the corresponding regions. The apparent diffusion coefficient map (B) is unremarkable. These features argue against acute cerebral ischemia. Discussion The exact pathogenesis of these transient lesions remains uncertain. Transient focal edema related to breakdown of the blood-brain barrier during a seizure has been postulated to be involved in the development of transient peri-ictal MRI abnormalities [7]. It is important to recognize the radiologic features of transient postictal abnormalities to differentiate them from ischemic, neoplastic, or infectious processes. Contrast enhancement of various intensity may be observed and may be related to alteration of blood– brain barrier [4]. Angiographic findings in the peri-ictal period suggest abnormal vascular permeability and “luxury perfusion” leading to focal edema [6]. Diffuse gyral and focal nodular enhancement and white matter hypo- or hyperdensity with and without mass effect have been described for these reversible lesions in the periictal period [1,3,10]. Diffusion-weighted MRI (DWI) has been proven useful for evaluation of acute ischemia [11]. In the ischemic region, DWI intensity is increased and the apparent diffusion coefficient map (ADC), a measure of water diffusion, is decreased. In our case, high DWI intensity suggests vasogenic edema; however, a lack of ADC intensity changes argues against ischemia. These findings are limited to the cortex and do not respect vascular territories. Neoplasm may be excluded based on the reversible nature of these lesions. Despite the resolution of these abnormalities, regional brain atrophy suggesting permanent brain injury has been reported in the literature [5]. The persistent left-sided visual field deficit in our patient most likely is another evidence for neuronal injury associated with these lesions. Conclusion Lack of significant abnormalities on follow-up imaging may support “benign” nature of these reversible peri-ictal changes. Patients with transient peri-ictal neuroimaging findings have undergone angiography or biopsy, with normal or nonspecific findings, and therefore, no change in therapy [8,12]. Recognition of these entities can encourage follow-up imaging to establish their transient nature and prevent unwarranted intervention. 482 Surg Neurol 2004;61:479 – 82 Cohen-Gadol et al duced by various convulsive agents. J Neuro Sci 1983; 59:305–22. 8. Rougier A, Loiseau P, Rivel J, Cohadon F, Orgogozo J. Partial epileptic seizures in four adolescents with abnormal CT scans, focal gliosis and spontaneous regression. Rev Neurol 1984;140:171–8. 9. Rumack C, Guggenheim M, Fasules J, Burdick D. Transient positive postictal computed tomographic scan. J Pediatr 1980;97:263–4. 10. Sammaritano M, Andermann F, Melanson D, et al. Prolonged focal cerebral edema associated with partial status epilepticus. Epilepsia 1985;26:334 –9. 11. Warach S, Gaa J, Siewert B. Acute human stroke studied by whole brain echo planar diffusion-weighted magnetic resonance imaging. Ann Neurol 1995;37: 231–41. 12. Zegers DBD, Hermanus N, Colle H, Goldman S. Focal seizures with reversible hypodensity on the CT scan. J Neurol Neurosurg Psychiatry 1985;48:187–8. COMMENTARY An axial T2-weighted MRI obtained 11 months later shows resolution of the right occipital abnormalities. 3 REFERENCES 1. Dillon W, Zawadzki M, Sherry R. Transient computed tomographic abnormalities after focal seizures. AJNR 1984;5:107–9. 2. Henry T, Drury I, Brunberg J, Pennell P, McKeever P, Beyboun A. Focal magnetic resonance changes associated with partial status epilepticus. Epilepsia 1994; 35:35–41. 3. Jayakumar P, Taly A, Mohan P. Transient computerized tomographic abnormalities following partial seizures. Acta Neurol Scand 1985;72:26 –9. 4. Kramer R, Luders H, Lesser R, et al. Transient focal abnormalities of neuroimaging studies during focal status epilepticus. Epilepsia 1987;28:528 –32. 5. Lansberg M, O’Brien M, Norbash A, Moseley M, Morrell M, Albers G. MRI abnormalities associated with partial status epilepticus. Neurology 1999;23: 1021–7. 6. Lee S, Goldberg H. Hypervascular pattern associated with idiopathic focal status epilepticus. Radiology 1977;125:159 –63. 7. Nitsch C, Klatzo I. Regional patterns of blood-brain barrier breakdown during epileptiform seizures in- This interesting case report documents a slightly different angle on a phenomenon that has been known for years: that cortex-supporting ictal activity has complex metabolic changes associated with it that may result in transient abnormalities visible by structural imaging. In this case, the structural image was produced by magnetic resonance. In the early 1980s, shortly after CT scanning became common, it was noted anecdotally that enhanced scans taken immediately after severe seizures or status epilepticus might show contrast enhancement in the region of the suspected epileptogenic focus. This was so commonly believed that several of us attempted this strategy as a way of helping to identify foci not associated with obvious structural lesions. It was never validated and, in my own personal experience, was capricious at best. Therefore, the strategy died. MRI, however, is much more sensitive and can show abnormalities never seen with CT scans. So, though the authors’ “take-home” message is to be aware of this potential phenomenon so as not to unnecessarily biopsy one of these lesions (which may be difficult to resist if the patient has never been scanned before), another message is that such transient lesions may provide clues to the location of epileptogenic foci that are not otherwise associated with obvious structural abnormalities. Allen R. Wyler, M.D. Vertis Neuroscience Seattle Washington