Functional Neuroimaging of Epilepsy



Epilepsy is a chronic progressive neurological disorder that affects 1% of the world population with an incidence of 70 per 100,000 per year [1]. About 30% of the patients have drug-resistant epilepsy [2]. Recent technical advances in neuroimaging have made many previously undetectable lesions visible, and magnetic resonance imaging (MRI) has become the primary imaging modality in the epilepsy workup. Many patients with temporal lobe epilepsy due to hippocampal sclerosis or cortical dysplasia have had temporal lobe resection and gained successful seizure control [3]. With modern neuroimaging, the surgical indications have expanded, and surgery is now one of the important treatment options in both adult and pediatric intractable epilepsy. It is known that seizure control is improved when the preoperative imaging demonstrates the border of the lesion [4]. Epilepsy surgery includes temporal lobectomy, extratemporal lesionectomy, hemispherectomy, corpus callosotomy, and subpial transections. The etiologies of surgically treatable epilepsy include hippocampal sclerosis, focal cortical dysplasia (FCD), tuberous sclerosis, neoplasm, perinatal stroke, vascular malformations, and much rarer diseases such as Rasmussen encephalitis and hemimegalencephaly. The role of the neuroradiologist for presurgical evaluation is not only to demonstrate a structural abnormality using multimodality techniques but also to ­provide anatomical information about the lesion in order to obtain improved postsurgical outcomes without causing unnecessary neurological deficits. As epilepsy is a functional disease, the lesion found in MRI is not always equivalent to the epileptogenic region. The neuroradiologist must work as a member of a team with neurologists and neurosurgeons to understand the clinical and electrophysiological assessments an to interpret the ­functional neuroimaging. Co-registration of the MRI, ­positron emission tomography (PET), single photon emission computed tomography (SPECT), functional MRI (fMRI), and magnetoencephalography (MEG) are fundamental to the presurgical evaluation. This multidisciplinary and multimodality approach is the key to the successful postsurgical outcomes. In this chapter, different techniques to explore intractable epilepsy are discussed, including fluorodeoxyglucose (FDG) PET, MEG, and diffusion tensor imaging­ (DTI) in combination with structural MRI.


Diffusion Tensor Imaging Tuberous Sclerosis Complex Epilepsy Surgery Hippocampal Sclerosis Focal Cortical Dysplasia 
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  1. 1.
    Hauser WA, Hesdorffer DC. Epilepsy: frequency, causes and consequences. NewYork: Demos Press; 1990.Google Scholar
  2. 2.
    Kwan P, Brodie MJ. Early identification of refractory epilepsy. N Eng J Med. 2000;342:314–9.CrossRefGoogle Scholar
  3. 3.
    Spencer S, Huh L. Outcomes of epilepsy surgery in adults and children. Lancet Neurol. 2008;7:525–37.PubMedCrossRefGoogle Scholar
  4. 4.
    Engel Jr J, Wiebe S, French J, Sperling M, Willamson P, Spencer D, et al. Practice parameter: temporal lobe and localized neocortical resections for epilepsy – report of the Quality Standards Subcommittee of the American Academy of Neurology, in association with the American Epilepsy Society and the American Association of Neurological Surgeons. Neurology. 2003;25(60):538–47.Google Scholar
  5. 5.
    Chugani HT, Phelps ME, Mazziotta JC. Positron emission tomography study of human brain functional development. Ann Neurol. 1987;22:487–97.PubMedCrossRefGoogle Scholar
  6. 6.
    Chugani HT. Functional brain imaging in pediatrics. Pediatr Clin North Am. 1992;39:777–99.PubMedGoogle Scholar
  7. 7.
    Engel J, Brown WJ, Kuhl DE, Phelps ME, Mazziotta JC, Crandall PH. Pathological findings underlying focal temporal lobe hypometabolism in partial epilepsy. Ann Neurol. 1982;12:518–28.PubMedCrossRefGoogle Scholar
  8. 8.
    Henry TR, Babb TL, Engel J, Mazziotta JC, Phelps ME, Crandall PH. Hippocampal neuronal loss and regional hypometabolism in temporal lobe epilepsy. Ann Neurol. 1994;36:925–7.PubMedCrossRefGoogle Scholar
  9. 9.
    Duncan JD, Moss SD, Bandy DJ, Manwaring K, Kaplan AM, Reiman EM, et al. Use of positron emission tomography for presurgical localization of eloquent brain areas in children with seizures. Pediatr Neurosurg. 1997;26:144–56.PubMedCrossRefGoogle Scholar
  10. 10.
    Sisodiya SM. Surgery for malformations of cortical development causing epilepsy. Brain. 2000;123(pt 6):1075–91.PubMedCrossRefGoogle Scholar
  11. 11.
    Kim SK, Na DG, Byun HS, Kim SE, Suh YL, Choi JY, et al. Focal cortical dysplasia: comparison of MRI and FDG-PET. J Comput Assist Tomogr. 2000;24:296–302.PubMedCrossRefGoogle Scholar
  12. 12.
    Kloss S, Pieper T, Pannek H, Holthausen H, Tuxhorn I. Epilepsy surgery in children with focal cortical dysplasia (FCD): results of long-term seizure outcome. Neuropediatrics. 2002;33:21–6.PubMedCrossRefGoogle Scholar
  13. 13.
    Salamon N, Kung J, Shaw SJ, Koo J, Koh S, Wu JY, et al. FDG-PET/MRI coregistration improves detection of cortical dysplasia in patients with epilepsy. Neurology. 2008;71:1594–601.PubMedCrossRefGoogle Scholar
  14. 14.
    Juhász C, Chugani DC, Muzik O, Shah A, Shah J, Watson C, et al. Relationship of flumazenil and glucose PET abnormalities to neocortical epilepsy surgery outcome. Neurology. 2001;56:1650–8.PubMedGoogle Scholar
  15. 15.
    Juhasz C, Chugani DC, Muzik O, et al. Alpha-methyl-l-tryptophan PET detects epileptogenic cortex in children with intractable epilepsy. Neurology. 2003;60:960–8.PubMedGoogle Scholar
  16. 16.
    Harvey AS, Cross JH, Shinnar S, Mathern BW. Defining the spectrum of international practice in pediatric epilepsy surgery patients. Epilepsia. 2008;49:146–55.PubMedCrossRefGoogle Scholar
  17. 17.
    Blumcke I, Thom M, Aronica E, Armstrong DD, Vinters HV, Palmini A, et al. The clinico-pathological spectrum of Focal Cortical Dysplasias a consensus classification proposed by an ad hoc Task Force of the ILAE Diagnostics Commission. Epilepsia. 2011;52:158–74.PubMedCrossRefGoogle Scholar
  18. 18.
    Mischel PS, Nguyen LP, Vinters HV. Cerebral cortical dysplasia associated with pediatric epilepsy: review of neuropathologic features and proposal for a grading system. J Neuropathol Exp Neurol. 1995;54:137–53.PubMedCrossRefGoogle Scholar
  19. 19.
    Palmini A, Najm I, Avanzini G, Babb T, Guerrini R, Foldvary-Schaefer N, et al. Terminology and classification of the cortical dysplasias. Neurology. 2004;62 Suppl 3:S2–8.PubMedGoogle Scholar
  20. 20.
    Kral T, von Lehe M, Podlogar M, Clusmann H, Sussmann P, Kurthen M, et al. Focal cortical dysplasia: long-term seizure outcome after surgical treatment. J Neurol Neurosurg Psychiatry. 2007;78:853–6.PubMedCrossRefGoogle Scholar
  21. 21.
    Widdess-Walsh P, Kellinghaus C, Jeha L, Kotagal P, Prayson R, Bingaman W, et al. Electro-clinical and imaging characteristics of focal cortical dysplasia: correlation with pathological subtypes. Epilepsy Res. 2005;67:25–33.PubMedCrossRefGoogle Scholar
  22. 22.
    Widdess-Walsh P, Jeha L, Nair D, Kotagal P, Bingaman W, Najim I. Subdural electrode analysis in focal cortical dysplasia: predictors of surgical outcome. Neurology. 2007;69:660–7.PubMedCrossRefGoogle Scholar
  23. 23.
    Chapman K, Wyllie E, Najm I, Ruggieri P, Bingaman W, Luders J, et al. Seizure outcome after epilepsy surgery in patients with normal preoperative MRI. J Neurol Neurosurg Psychiatry. 2005;76:710–3.PubMedCrossRefGoogle Scholar
  24. 24.
    Lerner JT, Salamon N, Hauptman JS, Velasco TR, Hemb M, Wu JY, et al. Assessment and surgical outcomes for mild type I and severe type II cortical dysplasia: a critical review and the UCLA experience. Epilepsia. 2009;50:1310–35.PubMedCrossRefGoogle Scholar
  25. 25.
    Hemn M, Velasco TR, Parnes M, Wu JY, Lerner JT, Matsumoto JH, et al. Improved outcomes in pediatric epilepsy surgery The UCLA experience, 1986–2008. Neurology. 2010;74:1768–75.CrossRefGoogle Scholar
  26. 26.
    Curatolo P, Bombardieri R, Verdecchia M, Seri S. Intractable seizures in tuberous sclerosis complex: from molecular pathogenesis to the rationale for treatment. J Child Neurol. 2005;20:318–25.PubMedCrossRefGoogle Scholar
  27. 27.
    Kalantari BN, Salamon N. Neuroimaging of tuberous sclerosis: spectrum of pathologic findings and frontiers in imaging. AJR. 2008;190:W304–9.PubMedCrossRefGoogle Scholar
  28. 28.
    Koh S, Jayakar P, Dunoyer C, Whiting SE, Resnick TJ, Alvarez LA, et al. Epilepsy surgery in children with tuberous sclerosis complex: presurgical evaluation and outcome. Epilepsia. 2000;41:1206–13.PubMedCrossRefGoogle Scholar
  29. 29.
    Wu JY, Salamon N, Kirsch HE, Mantle MM, Nagarajan SS, Kurelowech L, et al. Noninvasive testing, early surgery, and seizure freedom in tuberous sclerosis complex. Neurology. 2010;74:392–8.PubMedCrossRefGoogle Scholar
  30. 30.
    Chandra PS, Salamon N, Huang J, Wu JY, Koh S, Vinters H, et al. FDG-PET/MRI coregistration and diffusion-tensor imaging distinguish epileptogenic tubers and cortex in patients with tuberous sclerosis complex: a preliminary report. Epilepsia. 2006;47:1543–9.PubMedCrossRefGoogle Scholar
  31. 31.
    Chugani DC, Chugani HT, Muzik O, Shah JR, Shar AK, Canady A, et al. Imaging epileptogenic tubers in children with tuberous sclerosis complex using alpha-[11C]methyl- l-tryptophan positron emission tomography. Ann Neurol. 1998;44:858–66.PubMedCrossRefGoogle Scholar
  32. 32.
    Chugani HT, Chugani DC. Imaging of serotonin mechanisms in epilepsy. Epilepsy Curr. 2005;5:201–6.PubMedCrossRefGoogle Scholar
  33. 33.
    Leherichy S, Semah F, Hasboun D, Dormont D, Clemanceau S, Granat O, et al. Temporal lobe epilepsy with varying severity: MRI study of 222 patients. Neuroradiology. 1997;39:788–96.CrossRefGoogle Scholar
  34. 34.
    Gaillard WD, Bhatia S, Bookheimer SY, Fazilat S, Theodore WH. FDG-PET and volumetric MRI in the evaluation of patients with partial epilepsy. Neurology. 1995;45:123–12624.PubMedGoogle Scholar
  35. 35.
    Uijl SG, Leijten FS, Arends JB, Parra J, van Huffelen AC, Moons KG. The added value of [18F]-fluoro-D deoxyglucose positron emission tomography in screening for temporal lobe epilepsy surgery. Epilepsia. 2007;48:2121–9.PubMedCrossRefGoogle Scholar
  36. 36.
    Mintzer S, Cendes F, Soss J, Andermann F, Engel Jr J, Dubeau F, et al. Unilateral hippocampal sclerosis with contralateral temporal scalp ictal onset. Epilepsia. 2004;45:792–802.PubMedCrossRefGoogle Scholar
  37. 37.
    Lin JJ, Salamon N, Dutton RA, Lee AD, Geaga JA, Hayashi KM, et al. Three-dimensional preoperative maps of hippocampal atrophy predict surgical outcomes in temporal lobe epilepsy. Neurology. 2005;65:1094–7.PubMedCrossRefGoogle Scholar
  38. 38.
    Choi JY, Kim SJ, Hong SB, Seo DW, Hong SC, Kim BT, et al. Extratemporal hypometabolism on FDG PET in temporal lobe epilepsy as a predictor of seizure outcome after temporal lobectomy. Eur J Nucl Med Mol Imaging. 2003;30:581–7.PubMedCrossRefGoogle Scholar
  39. 39.
    Vinton AB, Carne R, Hicks RJ, Desmond PM, Kilpatrick C, Kaye AH, et al. The extent of resection of FDG-PET hypometabolism relates to outcome of temporal lobectomy. Brain. 2007;130(pt 2):548–60.PubMedCrossRefGoogle Scholar
  40. 40.
    Lamusuo S, Jutila L, Ylinen A, Kalviainen R, Mervaala E, Haaparanta M, et al. [18F]FDG-PET reveals temporal hypometabolism in patients with temporal lobe epilepsy even when quantitative MRI and histopathological analysis show only mild hippocampal damage. Arch Neurol. 2001;58:933–9.PubMedCrossRefGoogle Scholar
  41. 41.
    Juhász C, Chugani DC, Muzik O, Watson C, Shah J, Shah A, et al. Electroclinical correlates of flumazenil and fluorodeoxyglucose PET abnormalities in lesional epilepsy. Neurology. 2000;55:825–34.PubMedGoogle Scholar
  42. 42.
    Bauer R, Dobesberger J, Unterhofer C, Unterberger I, Walser G, Bauer G, et al. Outcome of adult patients with temporal lobe tumours and medically refractory focal epilepsy. Acta Neurochir (Wien). 2007;149:1211–6. discussion 1216–17.CrossRefGoogle Scholar
  43. 43.
    Hennessy MJ, Elwes RD, Honavar M, Rabe-Hesketh S, Binnie CD, Polkey CE. Predictors of outcome and pathological considerations in the surgical treatment of intractable epilepsy associated with temporal lobe lesions. J Neurol Neurosurg Psychiatry. 2001;70:450–8.PubMedCrossRefGoogle Scholar
  44. 44.
    Takahashi A, Hong SC, Seo DW, Hong SB, Lee M, Suh YL. Frequent association of cortical dysplasia in dysembryoplastic neuroepithelial tumor treated by epilepsy surgery. Surg Neurol. 2005;64:419–27.PubMedCrossRefGoogle Scholar
  45. 45.
    Im SH, Chung CK, Cho BK, Lee SK. Supratentorial ganglioglioma and epilepsy: postoperative seizure outcome. J Neurooncol. 2002;57:59–66.PubMedCrossRefGoogle Scholar
  46. 46.
    Kameyama S, Fukuda M, Tomikawa M, Morota N, Oishi M, Wachi M, et al. Surgical strategy and outcomes for epileptic patients with focal cortical dysplasia or dysembryoplastic neuroepithelial tumor. Epilepsia. 2001;42 suppl 6:37–41.PubMedGoogle Scholar
  47. 47.
    Baumgartner C, Barth DS, Levesque MF, Sutherling WW. Detection of epileptiform discharges on magnetoencephalography in comparison to invasive measurements. In: Hoke M, Erne SN, Okada YC, Romani GL, editors. Biomagnetism: clinical aspects. Amsterdam: Elsevier; 1992. p. 67–71.Google Scholar
  48. 48.
    Knowlton RC, Laxer KD, Aminoff MJ, Roberts TPL, Wong STC, Rowley HA. Magnetoencephalography in partial epilepsy: clinical yield and localization accuracy. Ann Neurol. 1997;42:622–31.PubMedCrossRefGoogle Scholar
  49. 49.
    Mikuni N, Nagamine T, Ikeda A, Terada K, Taki W, Kimura J, et al. Simultaneous recording of epileptiform discharges by MEG and subdural electrodes in temporal lobe epilepsy. Neuroimage. 1999;5:298–306.CrossRefGoogle Scholar
  50. 50.
    Stefan H, Hummel C, Scheler G, Genow A, Druschky K, Tilz C, et al. Magnetic brain source imaging of focal epileptic activity: a synopsis of 455 cases. Brain. 2003;126(Pt 11):2396–405.PubMedCrossRefGoogle Scholar
  51. 51.
    Knowlton RC. Current review in clinical science. Can magnetoencephalography aid epilepsy surgery? Epilepsy Curr. 2008;1:1–5.Google Scholar
  52. 52.
    Widjaja E, Otsubo H, Raybaud C, Ochi A, Chan D, Rutka JT, et al. Characteristics of MEG and MRI between Taylor’s focal cortical dysplasia (type II) and other cortical dysplasia: surgical outcome after complete resection of MEG spine source and MR lesion in pediatric cortical dysplasia. Epilepsy Res. 2008;82:147–55.PubMedCrossRefGoogle Scholar
  53. 53.
    Widjaja E, Simao G, Mahmoodabadi SZ, Ochi A, Snead OC, Rutha J, et al. Diffusion tensor imaging identifies changes in normal-apeparing white matter within the epileptogenic zone in tuberous sclerosis complex. Epilepsy Res. 2010;89:246–53.PubMedCrossRefGoogle Scholar
  54. 54.
    Lin JJ, Salamon N, Lee AD, Dutton RA, Geaga JA, Hayashi KM, et al. Reduced neocortical thickness and complexity mapped in mesial temporal lobe epilepsy with hippocampal sclerosis. Cereb Cortex. 2007;17:2007–18.PubMedCrossRefGoogle Scholar
  55. 55.
    Ahmadi ME, Hagler Jr DJ, McDonald CR, Tecoma ES, Iragui VJ, Dale AM, et al. Side matters: diffusion tensor imaging tractography in left and right temporal lobe epilepsy. AJNR Am J Neuroradiol. 2009;30(9):1740–7.PubMedCrossRefGoogle Scholar
  56. 56.
    Widjaja E, Blaser S, Miller E, Kassner A, Shannon P, Chuang SH, et al. Evaluation of subcortical white matter and deep white matter tracts in malformations of cortical developments. Epilepsia. 2007;48:1460–9.PubMedCrossRefGoogle Scholar
  57. 57.
    Widjaja E, Zarei MS, Otsubo H, Snead OC, Holowka S, Bells S, et al. Subcortical alteration in tissue microstructure adjacent to focal cortical dysplasia: detection at diffusion tensor imaging by using magnetoencephalographic dipole cluster localization. Radiology. 2009;251(1):206–15.PubMedCrossRefGoogle Scholar
  58. 58.
    Behrens E, Schramm J, Zentner J, Konig R. Surgical and neurological complications in a series of 708 epilepsy surgery procedures. Neurosurgery. 1997;41:1–10.PubMedCrossRefGoogle Scholar
  59. 59.
    Zhang J, Wilson CL, Levesque MF, Behnke EJ, Lufkin RB. Temperature changes in nickel-chromium intracranial depth electrodes during MR scanning. Am J Neuroradiol. 1993;14:497–500.PubMedGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.Department of RadiologyUCLA Medical CenterLos AngelesUSA

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