Yield of Brain Magnetic Resonance Imaging in Epilepsy Diagnosis from 1998 to 2020: A Large Retrospective Cohort Study

Abstract

Background We aimed to find the clinical significance of brain abnormalities on magnetic resonance imaging (MRI) in epilepsy and the lateralization of these findings with electroencephalogram (EEG).

Methods We retrospectively analyzed the results of all EEGs and brain MRIs of 600 consecutive epilepsy patients from 1998 to 2020.

Results Data were available for 563 cases (267 females). Ninety percent of the patients were 18 years old or younger. A total of 345 patients (61.3%) had focal epilepsy, 180 (32%), generalized, and 38 (6.7%), inconclusive. In 187 (33.2%), the first MRI was abnormal and in 81 (out of 108 repeated MRI), the second was pathological. The most frequent brain abnormalities were cortical dysplasia in 41 (18.1%), other structural abnormalities in 25 (11%), various phacomatoses in 23 (10.1%), and mesial temporal sclerosis in 17 (7.5%). Among 226 patients with abnormal MRI, 171 (75.6%) had focal epilepsy when compared with 36 (15.9%) with generalized epilepsy (p <0.001). In 121 patients (53.5%), the result of the abnormal MRI contributed significantly to the understanding of the epilepsy etiology. The side of abnormality was lateralized to the EEG focus in 120 cases (53%); in 10/15 cases with infantile spasms (66%), MRI was significantly abnormal. In 33, in whom the first MRI was normal, a second MRI revealed a significant abnormality.

Conclusion Brain MRI is an important tool in epilepsy diagnosis, mainly in focal seizures and infantile spasms. A repeat MRI is mandatory in intractable focal cases to improve the yield of this test.

Keywords

epilepsy diagnosis - brain MRI - EEG - clinical significance - semiology

Authors' Contribution

T.S. collected data from patients' files and constructed tables for final analysis. L.K. reviewed MRIs. H.G. designed and conceptualized the study and wrote the manuscript. All authors critically revised and approved the manuscript.

Patient Consent

Not required. IRB approval was given.

Publication History

Received: 15 September 2020

Accepted: 15 June 2021

Article published online:
29 July 2021

• References

• 1 Behr C, Goltzene MA, Kosmalski G, Hirsch E, Ryvlin P. Epidemiology of epilepsy. Rev Neurol (Paris) 2016; 172 (01) 27-36
• 2 Duncan J. The current status of neuroimaging for epilepsy. Curr Opin Neurol 2009; 22 (02) 179-184
• 3 Bien CG, Raabe AL, Schramm J, Becker A, Urbach H, Elger CE. Trends in presurgical evaluation and surgical treatment of epilepsy at one centre from 1988-2009. J Neurol Neurosurg Psychiatry 2013; 84 (01) 54-61
• 4 Rüber T, David B, Elger CE. MRI in epilepsy: clinical standard and evolution. Curr Opin Neurol 2018; 31 (02) 223-231
• 5 Gaillard WD, Cross JH, Duncan JS, Stefan H, Theodore WH. Task Force on Practice Parameter Imaging Guidelines for International League Against Epilepsy, Commission for Diagnostics. Epilepsy imaging study guideline criteria: commentary on diagnostic testing study guidelines and practice parameters. Epilepsia 2011; 52 (09) 1750-1756
• 6 Berg AT, Mathern GW, Bronen RA. et al. Frequency, prognosis and surgical treatment of structural abnormalities seen with magnetic resonance imaging in childhood epilepsy. Brain 2009; 132 (Pt 10): 2785-2797
• 7 Cascino GD. Advances in neuroimaging: surgical localization. Epilepsia 2001; 42 (01) 3-12
• 8 Berg AT, Berkovic SF, Brodie MJ. et al. Revised terminology and concepts for organization of seizures and epilepsies: report of the ILAE Commission on Classification and Terminology, 2005-2009. Epilepsia 2010; 51 (04) 676-685
• 9 Dixon WJ. BMDP Statistical Software. Los Angeles: University of California Press; 1993
• 10 Scheffer IE, Berkovic S, Capovilla G. et al. ILAE classification of the epilepsies: position paper of the ILAE commission for classification and terminology. Epilepsia 2017; 58 (04) 512-521
• 11 Colombo N, Salamon N, Raybaud C, Ozkara C, Barkovich AJ. Imaging of malformations of cortical development. Epileptic Disord 2009; 11 (03) 194-205
• 12 Blumcke I, Spreafico R, Haaker G. et al; EEBB Consortium. EEBB consortium. Histopathological findings in brain tissue obtained during epilepsy surgery. N Engl J Med 2017; 377 (17) 1648-1656
• 13 Bakhsh A. Value of neuroimaging in epilepsy: an experience from Pakistan. J Neurosci Rural Pract 2013; 4 (Suppl. 01) S35-S39
• 14 Bruno V, Klein JP, Nidup D. et al; Bhutan Epilepsy Project. Yield of brain MRI in clinically diagnosed epilepsy in the Kingdom of Bhutan: a prospective study. Ann Glob Health 2017; 83 (3-4): 415-422
• 15 Mac TL, Tran DS, Quet F, Odermatt P, Preux P-M, Tan CT. Epidemiology, aetiology, and clinical management of epilepsy in Asia: a systematic review. Lancet Neurol 2007; 6 (06) 533-543
• 16 Zhao X, Zhou Z, Zhu W, Xiang H. Role of conventional magnetic resonance imaging in the screening of epilepsy with structural abnormalities: a pictorial essay. Am J Nucl Med Mol Imaging 2017; 7 (03) 126-137
• 17 Ladino LD, Balaguera P, Rascovsky S. et al. Clinical benefit of 3 Tesla magnetic resonance imaging rescanning in patients with focal epilepsy and negative 1.5 Tesla magnetic resonance imaging. Rev Invest Clin 2016; 68 (03) 112-118
• 18 Knake S, Triantafyllou C, Wald LL. et al. 3T phased array MRI improves the presurgical evaluation in focal epilepsies: a prospective study. Neurology 2005; 65 (07) 1026-1031
• 19 McBride MC, Bronstein KS, Bennett B, Erba G, Pilcher W, Berg MJ. Failure of standard magnetic resonance imaging in patients with refractory temporal lobe epilepsy. Arch Neurol 1998; 55 (03) 346-348
• 20 Alvarez-Linera Prado J. 3-Tesla MRI and temporal lobe epilepsy. Semin Ultrasound CT MR 2007; 28 (06) 451-461