2006 Heart-Brain summit proceedings

Sudden unexplained death in epilepsy: The role of the heart

Stephan U. Schuele, MD

Department of Neurology
Cleveland Clinic, Cleveland, OH
Northwestern University,
Chicago, IL

Peter Widdess-Walsh, MD

Department of Neurology
Cleveland Clinic
Cleveland, OH

Adriana Bermeo, MD

Department of Neurology
Cleveland Clinic
Cleveland, OH

 

Hans O. Lüder, MD, PhD

Chairman, Department of Neurology
Cleveland Clinic
Cleveland, OH
ludersh@ccf.org

ARTICLE INTRODUCTION

Sudden unexplained death in epilepsy (SUDEP) is defined as the sudden, unexpected death of an otherwise healthy person with epilepsy without apparent cause. Death occurs during normal activities and under benign circumstances; it does not arise from trauma, aspiration, or intractable status epilepticus.

SUDEP is most commonly attributed to one of three mechanisms: seizure-induced central apnea, cardiac arrhythmia, and neurogenic pulmonary edema. This review will focus on the potential cardiac causes of SUDEP after providing a brief overview of SUDEP and its other proposed mechanisms.

CITATIONS

  1. Leestma JE, Kalelkar MB, Teas SS, Jay GW, Hughes JR.
    Sudden unexpected death associated with seizures: analysis of 66 cases. Epilepsia 1984; 25:84–88.
    http://www.ncbi.nlm.nih.gov/pubmed/6692796
  2. Ficker DM.
    Sudden unexplained death and injury in epilepsy. Epilepsia 2000; 41(Suppl 2):S7–S12.
    http://www.ncbi.nlm.nih.gov/pubmed/10885735
  3. Pedley TA, Hauser WA.
    Sudden death in epilepsy: a wake-up call for management. Lancet 2002; 359:1790–1791.
    http://www.ncbi.nlm.nih.gov/pubmed/12044369 (No abstract available.)
  4. Langan Y, Nashef L, Sander JW.
    Sudden unexpected death in epilepsy: a series of witnessed deaths. J Neurol Neurosurg Psychiatry 2000; 68:211–213.
    http://www.ncbi.nlm.nih.gov/pubmed/10644790
  5. Tomson T, Walczak T, Sillanpaa M, Sander JW.
    Sudden unexpected death in epilepsy: a review of incidence and risk factors. Epilepsia 2005; 46(Suppl 11):54–61.
    http://www.ncbi.nlm.nih.gov/pubmed/16393182
  6. Opeskin K, Berkovic SF.
    Risk factors for sudden unexpected death in epilepsy: a controlled prospective study based on coroner cases. Seizure 2003; 12:456–464.
    http://www.ncbi.nlm.nih.gov/pubmed/12967573
  7. Langan Y, Nashef L, Sander JW.
    Case-control study of SUDEP. Neurology 2005; 64:1131–1133.
    http://www.ncbi.nlm.nih.gov/pubmed/15824334
  8. Walczak TS, Leppik IE, D’Amelio M, et al.
    Incidence and risk factors in sudden unexpected death in epilepsy: a prospective cohort study. Neurology 2001; 56:519–525.
    http://www.ncbi.nlm.nih.gov/pubmed/11222798
  9. Tellez-Zenteno JF, Ronquillo LH, Wiebe S.
    Sudden unexpected death in epilepsy: evidence-based analysis of incidence and risk factors. Epilepsy Res 2005; 65:101–115.
    http://www.ncbi.nlm.nih.gov/pubmed/16005188
  10. Nilsson L, Farahmand BY, Persson PG, Thiblin I, Tomson T.
    Risk factors for sudden unexpected death in epilepsy: a case-control
    study. Lancet 1999; 353:888–893.
    http://www.ncbi.nlm.nih.gov/pubmed/10093982
  11. Sperling MR, Feldman H, Kinman J, Liporace JD, O’Connor MJ.
    Seizure control and mortality in epilepsy. Ann Neurol 1999; 46:45–50.
    http://www.ncbi.nlm.nih.gov/pubmed/10401779
  12. Hennessy MJ, Langan Y, Elwes RD, Binnie CD, Polkey CE, Nashef L.
    A study of mortality after temporal lobe epilepsy surgery.
    Neurology 1999; 53:1276–1283.
    http://www.ncbi.nlm.nih.gov/pubmed/10522885
  13. Timmings PL.
    Sudden unexpected death in epilepsy: is carbamazepine implicated? Seizure 1998; 7:289–291.
    http://www.ncbi.nlm.nih.gov/pubmed/9733403
  14. Nashef L, Fish DR, Garner S, Sander JW, Shorvon SD.
    Sudden death in epilepsy: a study of incidence in a young cohort with epilepsy and learning difficulty. Epilepsia 1995; 36:1187–1194.
    http://www.ncbi.nlm.nih.gov/pubmed/7489695
  15. Johnston SC, Horn JK, Valente J, Simon RP.
    The role of hypoventilation in a sheep model of epileptic sudden death. Ann Neurol 1995; 37:531–537.
    http://www.ncbi.nlm.nih.gov/pubmed/7717690
  16. Johnston SC, Siedenberg R, Min JK, Jerome EH, Laxer KD.
    Central apnea and acute cardiac ischemia in a sheep model of epileptic sudden death. Ann Neurol 1997; 42:588–594.
    http://www.ncbi.nlm.nih.gov/pubmed/9382470
  17. Nashef L, Walker F, Allen P, Sander JW, Shorvon SD, Fish DR.
    Apnea and bradycardia during epileptic seizures: relation to sudden death in epilepsy. J Neurol Neurosurg Psychiatry 1996; 60:297–300.
    http://www.ncbi.nlm.nih.gov/pubmed/8609507
  18. So EL, Sam MC, Lagerlund TL.
    Postictal central apnea as a cause of SUDEP: evidence from near-SUDEP incident. Epilepsia 2000; 41:1494–1497.
    http://www.ncbi.nlm.nih.gov/pubmed/11077466
  19. Terrence CF, Rao GR, Perper JA.
    Neurogenic pulmonary edema in unexpected, unexplained death of epileptic patients. Ann Neurol 1981; 9:458–464.
    http://www.ncbi.nlm.nih.gov/pubmed/7271241
  20. Swallow RA, Hillier CE, Smith PE.
    Sudden unexplained death in epilepsy (SUDEP) following previous seizure-related pulmonary oedema: case report and review of possible preventative treatment. Seizure 2002; 11:446–448.
    http://www.ncbi.nlm.nih.gov/pubmed/12237072
  21. Johnston SC, Darragh TM, Simon RP.
    Postictal pulmonary edema requires pulmonary vascular pressure increases. Epilepsia 1996; 37:428–432.
    http://www.ncbi.nlm.nih.gov/pubmed/8617170
  22. Hilz MJ, Devinsky O, Doyle W, Mauerer A, Dutsch M.
    Decrease of sympathetic cardiovascular modulation after temporal lobe epilepsy surgery. Brain 2002; 125:985–995.
    http://www.ncbi.nlm.nih.gov/pubmed/11960889
  23. Winslow RD, Mehta D, Fuster V.
    Sudden cardiac death: mechanisms, therapies and challenges. Nat Clin Pract Cardiovasc Med 2005; 2:352–360.
    http://www.ncbi.nlm.nih.gov/pubmed/16265561
  24. Pogwizd SM, Hoyt RH, Saffitz JE, Corr PB, Cox JL, Cain ME.
    Reentrant and focal mechanisms underlying ventricular tachycardia in the human heart. Circulation 1992; 86:1872–1887.
    http://www.ncbi.nlm.nih.gov/pubmed/1451259
  25. Josephson ME, Almendral JM, Buxton AE, Marchlinski FE.
    Mechanisms of ventricular tachycardia. Circulation 1987;
    75:III41–III47.
    http://www.ncbi.nlm.nih.gov/pubmed/3829361 (No abstract available.)
  26. Schwartz PJ, La Rovere MT, Vanoli E.
    Autonomic nervous system and sudden cardiac death: experimental basis and clinical observations for post-myocardial infarction risk stratification. Circulation 1992; 85(Suppl 1):I77–I91.
    http://www.ncbi.nlm.nih.gov/pubmed/1728509
  27. odrid PJ, Myerburg RJ.
    Epidemiology and stratification of risk for sudden cardiac death. Clin Cardiol 2005; 28(Suppl 1):I3–I11.
    http://www.ncbi.nlm.nih.gov/pubmed/16450807
  28. Wever EF, Robles de Medina EO.
    Sudden death in patients without structural heart disease. J Am Coll Cardiol 2004; 43:1137–1144.
    http://www.ncbi.nlm.nih.gov/pubmed/15063419
  29. Coumel P, Fidelle J, Lucet V, Attuel P, Bouvrain Y.
    Catecholamineinduced severe ventricular arrhythmias with Adam-Stokes syndrome in children: report of four cases. Br Heart J 1978; 40(Suppl):28–37. (No web link found.)
  30. Priori SG, Napolitano C, Tiso N, et al.
    Mutations in the cardiac ryanodine receptor gene (hRyR2) underlie catecholaminergic polymorphic ventricular tachycardia. Circulation 2001; 103:196–200.
    http://www.ncbi.nlm.nih.gov/pubmed/11208676
  31. Grubb BP.
    Clinical practice: neurocardiogenic syncope. N Engl J Med 2005; 352:1004–1010.
    http://www.ncbi.nlm.nih.gov/pubmed/15758011 (No abstract available.)
  32. Strickberger SA, Benson DW, Biaggioni I, et al.
    AHA/ACCF scientific statement on the evaluation of syncope: from the American Heart Association Councils on Clinical Cardiology, Cardiovascular Nursing, Cardiovascular Disease in the Young, and Stroke, and the Quality of Care and Outcomes Research Interdisciplinary Working Group; and the American College of Cardiology Foundation: in collaboration with the Heart Rhythm Society: endorsed by the American Autonomic Society. Circulation 2006; 113:316–327.
    http://www.ncbi.nlm.nih.gov/pubmed/16418451 (No abstract available.)
  33. Connolly SJ, Sheldon R, Thorpe KE, et al.
    Pacemaker therapy for prevention of syncope in patients with recurrent severe vasovagal syncope: second vasovagal pacemaker study (VPS II): a randomized trial. JAMA 2003; 289:2224–2229.
    http://www.ncbi.nlm.nih.gov/pubmed/12734133
  34. Raviele A, Giada F, Menozzi C, et al.
    A randomized, double-blind, placebo-controlled study of permanent cardiac pacing for the treatment of recurrent tilt-induced vasovagal syncope: the vasovagal syncope and pacing trial (SYNPACE). Eur Heart J 2004; 25:1741–1748.
    http://www.ncbi.nlm.nih.gov/pubmed/15451153
  35. Soteriades ES, Evans JC, Larson MG, et al.
    Incidence and prognosis of syncope. N Engl J Med 2002; 347:878–885.
    http://www.ncbi.nlm.nih.gov/pubmed/12239256
  36. Benarroch EE.
    The central autonomic network. In: Low PA, ed. Clinical Autonomic Disorders. 2nd ed. Philadelphia, PA: Lippincott-Raven Publishers; 1997:17–23. (No web link found.)
  37. Britton JW, Benarroch E.
    Seizures and syncope: anatomic basis and diagnostic considerations. Clin Auton Res 2006; 16:18–28.
    http://www.ncbi.nlm.nih.gov/pubmed/16477491
  38. Gibbins IL.
    Peripheral autonomic nervous system. In: Paxinos G, ed. The Human Nervous System. San Diego, CA: Academic Press, Inc; 1990:93–123. (No web link found.)
  39. Janig W, Habler HJ.
    Organization of the autonomic nervous system: structure and function. In: Appenzeller O, ed. Handbook of Clinical Neurology. The Autonomic Nervous System. Part I. Normal Functions. Amsterdam, The Netherlands: Elsevier; 1999:1–52. (No web link found.)
  40. Paton JF, Boscan P, Pickering AE, Nalivaiko E.
    The yin and yang of cardiac autonomic control: vago-sympathetic interactions revisited. Brain Res Brain Res Rev 2005; 49:555–565.
    http://www.ncbi.nlm.nih.gov/pubmed/16269319
  41. Freeman JV, Dewey FE, Hadley DM, Myers J, Froelicher VF.
    Autonomic nervous system interaction with the cardiovascular system during exercise. Prog Cardiovasc Dis 2006; 48:342–362.
    http://www.ncbi.nlm.nih.gov/pubmed/16627049
  42. Spyer KM.
    Annual review prize lecture: central nervous mechanisms contributing to cardiovascular control. J Physiol 1994; 474:1–19.
    http://www.ncbi.nlm.nih.gov/pubmed/8014887 (No abstract available.)
  43. Taylor J, Holmes G, Walshe FMR, eds.
    Selected writings of John Hughlings Jackson. London: Hodder & Stoughton, Ltd; 1931. (No web link found.)
  44. Mulder DW, Daly D, Bailey AA.
    Visceral epilepsy. Arch Intern Med 1954; 93:481–493.
    http://www.ncbi.nlm.nih.gov/pubmed/13137624 (No abstract available.)
  45. Penfield W.
    Diencephalic autonomic epilepsy. Arch Neurol Psychiatry 1929; 22:358–374. (No web link found.)
  46. Devinsky O.
    Effects of seizures on autonomic and cardiovascular function. Epilepsy Curr 2004; 4:43–46.
    http://www.ncbi.nlm.nih.gov/pubmed/15562299
  47. Oppenheimer SM, Gelb A, Girvin JP, Hachinski VC.
    Cardiovascular effects of human insular cortex stimulation.
    Neurology 1992; 42:1727–1732.
    http://www.ncbi.nlm.nih.gov/pubmed/1513461
  48. Oppenheimer S.
    Cerebrogenic cardiac arrhythmias: cortical lateralization and clinical significance. Clin Auton Res 2006; 16:6–11.
    http://www.ncbi.nlm.nih.gov/pubmed/16477489
  49. Critchley HD, Corfield DR, Chandler MP, Mathias CJ, Dolan RJ.
    Cerebral correlates of autonomic cardiovascular arousal: a functional neuroimaging investigation in humans. J Physiol 2000; 523:259–270.
    http://www.ncbi.nlm.nih.gov/pubmed/10673560
  50. Critchley HD, Mathias CJ, Josephs O, et al.
    Human cingulate cortex and autonomic control: converging neuroimaging and clinical evidence. Brain 2003; 126:2139–2152.
    http://www.ncbi.nlm.nih.gov/pubmed/12821513
  51. Critchley HD.
    The human cortex responds to an interoceptive challenge. Proc Natl Acad Sci U S A 2004; 101:6333–6334.
    http://www.ncbi.nlm.nih.gov/pubmed/15096592 (No abstract available.)
  52. Topolovec JC, Gati JS, Menon RS, Shoemaker JK, Cechetto DF.
    Human cardiovascular and gustatory brainstem sites observed by functional magnetic resonance imaging. J Comp Neurol 2004; 471:446–461.
    http://www.ncbi.nlm.nih.gov/pubmed/15022263
  53. Jokeit H, Noerpel I, Herbord E, Ebner A.
    Heart rate does not decrease after right hemispheric amobarbital injection. Neurology 2000; 54:2347–2348.
    http://www.ncbi.nlm.nih.gov/pubmed/10881273 (No abstract available.)
  54. Zamrini EY, Meador KJ, Loring DW, et al.
    Unilateral cerebral inactivation produces differential left/right heart rate responses. Neurology 1990; 40:1408–1411.
    http://www.ncbi.nlm.nih.gov/pubmed/2392227
  55. Yoon BW, Morillo CA, Cechetto DF, Hachinski V.
    Cerebral hemispheric lateralization in cardiac autonomic control. Arch Neurol 1997; 54:741–744.
    http://www.ncbi.nlm.nih.gov/pubmed/9193209
  56. Oppenheimer SM, Cechetto DF.
    Cardiac chronotropic organization of the rat insular cortex. Brain Res 1990; 533:66–72.
    http://www.ncbi.nlm.nih.gov/pubmed/2085734
  57. Oppenheimer SM, Wilson JX, Guiraudon C, Cechetto DF.
    Insular cortex stimulation produces lethal cardiac arrhythmias: a mechanism of sudden death? Brain Res 1991; 550:115–121.
    http://www.ncbi.nlm.nih.gov/pubmed/1888988
  58. Lathers CM, Schraeder PL, Weiner FL.
    Synchronization of cardiac autonomic neural discharge with epileptogenic activity: the lockstep phenomenon. Electroencephalogr Clin Neurophysiol 1987; 67:247–259.
    http://www.ncbi.nlm.nih.gov/pubmed/2441959
  59. Zaatreh MM, Quint SR, Tennison MB, D’Cruz O, Vaughn BB.
    Heart rate variability during interictal epileptiform discharges.
    Epilepsy Res 2003; 54:85–90.
    http://www.ncbi.nlm.nih.gov/pubmed/12837559
  60. Lown B, Verrier RL, Rabinowitz SH.
    Neural and psychologic mechanisms and the problem of sudden cardiac death. Am J Cardiol 1977; 39:890–902.
    http://www.ncbi.nlm.nih.gov/pubmed/860697
  61. Kleiger RE, Miller JP, Bigger JT Jr, Moss AJ.
    Decreased heart rate variability and its association with increased mortality after acutemyocardial infarction. Am J Cardiol 1987; 59:256–262.
    http://www.ncbi.nlm.nih.gov/pubmed/3812275
  62. Dasheiff RM, Dickinson LJ.
    Sudden unexpected death of epileptic patient due to cardiac arrhythmia after seizure. Arch Neurol 1986; 43:194–196.
    http://www.ncbi.nlm.nih.gov/pubmed/3947265
  63. Ansakorpi H, Korpelainen JT, Suominen K, Tolonen U, Myllyla VV, Isojarvi JI.
    Interictal cardiovascular autonomic responses in
    patients with temporal lobe epilepsy. Epilepsia 2000; 41:42–47.
    http://www.ncbi.nlm.nih.gov/pubmed/10643922
  64. Isojarvi JI, Ansakorpi H, Suominen K, Tolonen U, Repo M, Myllyla VV.
    Interictal cardiovascular autonomic responses in patients with
    epilepsy. Epilepsia 1998; 39:420–426.
    http://www.ncbi.nlm.nih.gov/pubmed/9578032
  65. Devinsky O, Perrine K, Theodore WH.
    Interictal autonomic nervous system function in patients with epilepsy. Epilepsia 1994; 35:199–204.
    http://www.ncbi.nlm.nih.gov/pubmed/8112246
  66. Ferri R, Curzi-Dascalova L, Arzimanoglou A, et al.
    Heart rate variability during sleep in children with partial epilepsy. J Sleep Res 2002; 11:153–160.
    http://www.ncbi.nlm.nih.gov/pubmed/12028480
  67. Ansakorpi H, Korpelainen JT, Tanskanen P, et al.
    Cardiovascular regulation and hippocampal sclerosis. Epilepsia 2004; 45:933–939.
    http://www.ncbi.nlm.nih.gov/pubmed/15270759
  68. Ansakorpi H, Korpelainen JT, Huikuri HV, Tolonen U, Myllyla VV, Isojarvi JI.
    Heart rate dynamics in refractory and well controlled
    temporal lobe epilepsy. J Neurol Neurosurg Psychiatry 2002;
    72:26–30.
    http://www.ncbi.nlm.nih.gov/pubmed/11784820
  69. Annegers JF, Coan SP, Hauser WA, Leestma J.
    Epilepsy, vagal nerve stimulation by the NCP system, all-cause mortality, and sudden, unexpected, unexplained death. Epilepsia 2000; 41:549–553.
    http://www.ncbi.nlm.nih.gov/pubmed/10802760
  70. Schachter SC.
    Therapeutic effects of vagus nerve stimulation in epilepsy and implications for sudden unexpected death in epilepsy. Clin Auton Res 2006; 16:29–32.
    http://www.ncbi.nlm.nih.gov/pubmed/16477492
  71. Tavernor SJ, Brown SW, Tavernor RM, Gifford C.
    Electrocardiograph QT lengthening associated with epileptiform EEG discharges— a role in sudden unexplained death in epilepsy? Seizure 1996; 5:79–83.
    http://www.ncbi.nlm.nih.gov/pubmed/8777558
  72. Oppenheimer S.
    Cardiac dysfunction during seizures and the sudden epileptic death syndrome. J R Soc Med 1990; 83:134–136.
    http://www.ncbi.nlm.nih.gov/pubmed/2182856 (No abstract available.)
  73. Fauchier L, Babuty D, Cosnay P.
    Epilepsy, Brugada syndrome and the risk of sudden unexpected death. J Neurol 2000; 247:643–644.
    http://www.ncbi.nlm.nih.gov/pubmed/11041334 (No abstract available.)
  74. Tigaran S, Molgaard H, McClelland R, Dam M, Jaffe AS.
    Evidence of cardiac ischemia during seizures in drug refractory epilepsy patients. Neurology 2003; 60:492–495.
    http://www.ncbi.nlm.nih.gov/pubmed/12578934
  75. Nei M, Ho RT, Abou-Khalil BW, et al.
    EEG and ECG in sudden unexplained death in epilepsy. Epilepsia 2004; 45:338–345.
    http://www.ncbi.nlm.nih.gov/pubmed/15030496
  76. Woodruff BK, Britton JW, Tigaran S, et al.
    Cardiac troponin levels following monitored epileptic seizures. Neurology 2003; 60:1690–1692.
    http://www.ncbi.nlm.nih.gov/pubmed/12771269
  77. Bergen DC.
    In a heartbeat: autonomic changes during seizures. Epilepsy Curr 2005; 5:194–196.
    http://www.ncbi.nlm.nih.gov/pubmed/16175223 (No abstract available.)
  78. Tinuper P, Bisulli F, Cerullo A, et al.
    Ictal bradycardia in partial epileptic seizures: autonomic investigation in three cases and literature review. Brain 2001; 124:2361–2371.
    http://www.ncbi.nlm.nih.gov/pubmed/11701591
  79. Reeves AL, Nollet KE, Klass DW, Sharbrough FW, So EL.
    The ictal bradycardia syndrome. Epilepsia 1996; 37:983–987.
    http://www.ncbi.nlm.nih.gov/pubmed/8822697
  80. Opherk C, Coromilas J, Hirsch LJ.
    Heart rate and EKG changes in 102 seizures: analysis of influencing factors. Epilepsy Res 2002; 52:117–127.
    http://www.ncbi.nlm.nih.gov/pubmed/12458028
  81. Leutmezer F, Schernthaner C, Lurger S, Potzelberger K, Baumgartner C.
    Electrocardiographic changes at the onset of epileptic
    seizures. Epilepsia 2003; 44:348–354.
    http://www.ncbi.nlm.nih.gov/pubmed/12614390
  82. Nei M, Ho RT, Sperling MR.
    EKG abnormalities during partial seizures in refractory epilepsy. Epilepsia 2000; 41:542–548.
    http://www.ncbi.nlm.nih.gov/pubmed/10802759
  83. Britton JW, Ghearing GR, Benarroch EE, Cascino GD.
    The ictal bradycardia syndrome: localization and lateralization. Epilepsia 2006; 47:737–744.
    http://www.ncbi.nlm.nih.gov/pubmed/16650140
  84. Rocamora R, Kurthen M, Lickfett L, Von Oertzen J, Elger CE.
    Cardiac asystole in epilepsy: clinical and neurophysiologic features.
    Epilepsia 2003; 44:179–185.
    http://www.ncbi.nlm.nih.gov/pubmed/12558571
  85. Rugg-Gunn FJ, Simister RJ, Squirrell M, Holdright DR, Duncan JS.
    Cardiac arrhythmias in focal epilepsy: a prospective long-term
    study. Lancet 2004; 364:2212–2219.
    http://www.ncbi.nlm.nih.gov/pubmed/15610808
  86. Altenmuller DM, Zehender M, Schulze-Bonhage A.
    High-grade atrioventricular block triggered by spontaneous and stimulationinduced epileptic activity in the left temporal lobe. Epilepsia 2004; 45:1640–1644.
    http://www.ncbi.nlm.nih.gov/pubmed/15571524
  87. Hirsch LJ, Hauser WA.
    Can sudden unexplained death in epilepsy be prevented? Lancet 2004; 364:2157–2158.
    http://www.ncbi.nlm.nih.gov/pubmed/15610785 (No absract available.)
  88. P-Codrea Tigaran S, Dalager-Pedersen S, Baandrup U, Dam M, Vesterby-Charles A.
    Sudden unexpected death in epilepsy: is death
    by seizures a cardiac disease? Am J Forensic Med Pathol 2005;
    26:99–105.
    http://www.ncbi.nlm.nih.gov/pubmed/15897710
  89. Falconer B, Rajs J.
    Post-mortem findings of cardiac lesions in epileptics: a preliminary report. Forensic Sci 1976; 8:63–71.
    http://www.ncbi.nlm.nih.gov/pubmed/824190
  90. Natelson BH, Suarez RV, Terrence CF, Turizo R.
    Patients with epilepsy who die suddenly have cardiac disease. Arch Neurol 1998; 55:857–860.
    http://www.ncbi.nlm.nih.gov/pubmed/9626779

  91. Stollberger C, Finsterer J.
    Cardiorespiratory findings in sudden unexplained/unexpected death in epilepsy (SUDEP). Epilepsy Res 2004; 59:51–60.
    http://www.ncbi.nlm.nih.gov/pubmed/15135167