Reassessment: Neuroimaging in the emergency patient presenting with seizure an evidence-based review

1. Reassessment: Neuroimaging in the emergency patient presenting with seizure (an evidence-based review) Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology C. L. Harden, J. S. Huff, T. H. Schwartz, R. M. Dubinsky, R. D. Zimmerman, S. Weinstein, J. C. Foltin, and W. H. Theodore

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3. Presentation Objectives

4. Overview

5. Background

6. Gaps in Care

7. AAN Guideline Process

8. Clinical Questions

9.

10. AAN Classification of Evidence

11. AAN Level of Recommendations

12. Translating Class to Recommendations A = Requires at least two consistent Class I studies.* B = Requires at least one Class I study or at least two consistent Class II studies. C = Requires at least one Class II study or two consistent Class III studies. U = Studies not meeting criteria for Class I ? Class III.

13. Translating Class to Recommendations, cont. * In exceptional cases, one convincing Class I study may suffice for an �A� recommendation if 1) all criteria are met, 2) the magnitude of effect is large (relative rate improved outcome >5 and the lower limit of the confidence interval is >2).

14. Applying This Processto the Issue We will now turn our attention to the guidelines.

15. Clinical Questions What is the likelihood that acute management, for the adult emergency patient presenting with a first seizure, is changed because of the results of a neuroimaging study? What is the likelihood that acute management for the pediatric emergency patient presenting with a first seizure (not excluding complex febrile seizures) will change based on the results of a neuroimaging study? What is the likelihood that acute management for the emergency patient presenting with a chronic seizure will be changed by the results of a neuroimaging study?

16. Clinical Questions, cont. What is the likelihood that the results of a neuroimaging study will lead to a change in acute management in special populations presenting with seizure (age 6 months, AIDS, children with immediate posttraumatic seizures)? What factors are associated with an abnormal neuroimaging study for patients presenting with seizure in the emergency department?

17. Methods Ovid Medline� 1966 to November 2004 Relevant, fully published, peer-reviewed articles

18. Methods, cont. Search terms diagnostic imaging, neuroimaging seizures, epilepsy emergency medical services, emergencies, craniocerebral trauma neurocysticercosis, HIV infection, status epilepticus* *Terms specifically searched because these are common conditions known to be associated with structural brain lesions and seizures, especially first seizures

19. Methods, cont. At least four panelists reviewed each article for inclusion. Risk of bias was determined using the classification of evidence for each study (Classes I�IV). Strength of practice recommendations were linked directly to levels of evidence (Levels A, B, C, and U). Conflicts of interest were disclosed.

20. Literature Review

21. Class I: A statistical, population-based sample of patients studied at a uniform point in time (usually early) during the course of the condition. All patients undergo the intervention of interest. The outcome, if not objective, is determined in an evaluation that is masked to the patients� clinical presentation. Class II: A statistical, non-referral-clinic-based sample of patients studied at a uniform point in time (usually early) during the course of the condition. Most patients undergo the intervention of interest. The outcome, if not objective, is determined in an evaluation that is masked to the patients� clinical presentations. AAN Classification of Evidencefor Screening

22. Class III: A sample of patients studied during the course of the condition. Some patients undergo the intervention of interest. The outcome, if not objective, is determined in an evaluation by someone other than the treating physician. Class IV: Expert opinion, case reports, or any study not meeting criteria for Class I to III. AAN Classification of Evidencefor Screening, cont.

23. Analysis of Evidence Question 1: What is the likelihood that acute management, for the adult emergency patient presenting with a first seizure, is changed because of the results of a neuroimaging study?

24. Analysis of Evidence, cont. Overall, five Class III studies2-6 (3,4,7-9) of CT scans in the emergency department for adults presenting with seizure resulted in a change of acute management in 9% to 17% of patients. Frequent CT abnormalities that changed acute management were traumatic brain injury, subdural hematomas, nontraumatic bleeding, cerebrovascular accidents, tumors, and brain abscesses.

25. Conclusion and Recommendation Conclusion: An emergency CT in adults with first seizure is possibly useful for acute management of the patient (Class III). Recommendation: An emergency CT may be considered in adults with first seizure (Level C).

26. Analysis of Evidence Question 2: What is the likelihood that acute management for the pediatric emergency patient presenting with a first seizure (not excluding complex febrile seizures) will change based on the results of a neuroimaging study?

27. Analysis of Evidence, cont. Overall, four Class III studies7-10 (10,11,13,14) of CT scans in the emergency department for children presenting with seizure resulted in a change of acute management in 3% to 8% of patients. Frequent CT abnormalities that resulted in a change in acute management were cerebral hemorrhages, tumors, cysticercosis, and obstructive hydrocephalus.

28. Conclusion and Recommendation Conclusion: An emergency CT in children with a first seizure is possibly useful for acute management of the patient (Class III). Recommendation: An emergency CT may be considered in children with a first seizure (Level C).

29. Analysis of Evidence Question 3: What is the likelihood that acute management for the emergency patient presenting with a chronic seizure will be changed by the results of a neuroimaging study?

30. Analysis of Evidence, cont. Three Class III studies11-13(2,6,15) involved patients in the emergency department presenting with either chronic or first seizure, 12% to 25% of whom had abnormal CT scans (frequently of cerebral hemorrhages and shunt malfunctions). Evidence for the likelihood of an imaging study changing management for emergency patients with chronic seizures is not available.

31. Conclusion and Recommendation Conclusion: The evidence is inadequate to support or refute the usefulness of emergency CT in persons with chronic seizures. Recommendation: There is no recommendation regarding an emergency CT in persons with chronic seizures (Level U).

32. Analysis of Evidence Question 4: What is the likelihood that the results of a neuroimaging study will lead to a change in acute management in special populations presenting with seizure (age 6 months, AIDS, children with immediate posttraumatic seizures?

33. Analysis of Evidence, cont. The following was found in three Class III studies14-16(5,12,16) of significantly abnormal CT scans in the emergency department: For 22 children less than 6 months of age presenting with seizure, a change of acute management occurred in 55% of patients (findings included Aicardi syndrome, Miller-Diecker syndrome, tuberous sclerosis, an infarct, and a depressed skull fracture).16(16) For 26 patients with AIDS studied, 18 had atrophy on CT and 7 (28%) had CT findings that changed management14(5) (findings included mass lesions and CNS toxoplasmosis; for 2 patients with follow-up MRI, PML was found). For 62 children with immediate posttraumatic seizures, 16% had abnormal CT scans and 3 patients, about 5%, had abnormalities that led to a surgical intervention.15(12)

34. Conclusion and Recommendation Conclusion: An emergency CT in children less than 6 months of age and in patients with AIDS is possibly useful for acute management (Class III). Recommendation: An emergency CT may be considered in children less than 6 months of age and in patients with AIDS (Level C).

35. Analysis of Evidence Question 5: What factors are associated with an abnormal neuroimaging study for patients presenting with seizure in the emergency department?

36. Analysis of Evidence, cont. Eight Class II3,5,7,8,10,12,13,17(4,6-8,10,11,14,15) studies and one Class III6(9) study reported on clinical and historical features associated with an abnormal CT result. Factors associated with abnormal CT scans included the following: Focal abnormality on neurologic examination (adult and pediatric age groups) A predisposing history7,10,13(10,14,15) (ages 21 and under) Focal onset of seizure7,8(10,11) (ages 21 and under)

37. Conclusion and Recommendation Conclusion: The clinical and historical features of an abnormal neurologic examination, a predisposing history, or a focal seizure onset are probably predictive of an abnormal CT study for patients presenting with seizures in the emergency department (Class II). Recommendation: An emergency CT should be considered in patients presenting with seizure in the emergency department who have an abnormal neurologic examination, predisposing history, or focal seizure onset (Level B).

38. Gaps in the Evidence The evidence available does not support strong recommendations because of methodologic limitations of the studies. The available studies from which evidence was derived for using computerized transaxial tomography (CTT) as a screening procedure for altering acute management in the emergency patient presenting with seizure were Class III. A higher class of evidence requires masking of the clinical presentation. However, emergent seizure treatment does not lend itself easily to a study design including masking to the clinical presentation. One of the main limitations of available data is the variation in patient population among studies. Most had nonsystematic inclusion criteria and limited numbers of subjects. Further, the data available do not allow us to comment on the systematic use of contrast CT vs noncontrast CT. None of the available studies included more than very limited, nonsystematic data on MRI.

39. Future Research Future research should address the use of brain MRI in this clinical setting. At present, insufficient data are available to make any recommendations regarding the emergent or semi-emergent use of MRI, which may potentially have greater sensitivity than CT for detecting brain pathology underlying seizure disorders. Moreover, many of the studies reviewed were performed on older CT scanners, which might have lower sensitivity than later models. The role of contrast administration for both modalities needs to be assessed. Important unanswered questions include, particularly for MRI, consideration of risks in scanning potentially unstable patients. As emergency MRI use becomes more prevalent, but CT technology improves, multicenter studies, ideally including both imaging modalities, with a second set of blinded readers will be necessary to achieve adequate statistical power, particularly to investigate the predictive value of clinical data.

40. Future Research, cont. Further studies should also include better outcome and follow-up data, such as information on patients starting antiseizure medicines or changing antiseizure medicine doses in the emergency department, and on patients presenting with seizures who have normal imaging. However, given the expense of these approaches, it might be possible to use electronic medical records to obtain prospective data on the usefulness of neuroimaging in the emergency department for patients presenting with seizures. It will be particularly useful to segregate results by age, including pediatric and elderly patients. New analytic methods will have to be developed to make optimal use of data acquired in a clinical, rather than research, context.

41. Reference Report of the Quality Standards Subcommittee of the American Academy of Neurology in cooperation with American College of Emergency Physicians, American Association of Neurological Surgeons, and American Society of Neuroradiology. Practice Parameter: Neuroimaging in the emergency patient presenting with seizure: summary statement. Neurology 1996;47:288�291. (1) Henneman PL, DeRoos F, Lewis RJ. Determining the need for admission in patients with new-onset seizures. Ann Emerg Med 1994;24:1108�1114. (3) Mower WR, Biros MH, Talan DA, Moran GJ, Ong S. Selective tomographic imaging of patients with newonset seizure disorders. Acad Emerg Med 2002;9:43�47. (4) Schoenenberger RA, Heim SM. Indication for computed tomography of the brain in patients with first uncomplicated generalised seizure. BMJ 1994;309:986�989. (7) Sempere AP, Villaverde FJ, Martinez-Menendez B, Cabeza C, Pena P, Tejerina JA. First seizure in adults: a prospective study from the emergency department. Acta Neurol Scand 1992;86:134�138. (8) Tardy B, Lafond P, Convers P, et al. Adult first generalized seizure: etiology, biological tests, EEG, CT scan, in an ED. Am J Emerg Med 1995;13:1�5. (9)

42. Reference Sharma S, Riviello JJ, Harper MB, Baskin MN. The role of emergent neuroimaging in children with new onset afebrile seizures. Pediatrics 2003;111:1�5. (10) Garvey MA, Gaillard WD, Rusin JA, et al. Emergency brain computed tomography in children with seizures: who is most likely to benefit? J Pediatr 1998;133:664�669. (11) Landfish N, Gieron-Korthals M, Weibley RE, Panzarino V. New onset childhood seizures. Emergency department experience. J Fl Med Assoc 1992;79:697�700. (13) Maytal J, Krauss JM, Novak G, Nagelberg J, Patel M. The role of brain computed tomography in evaluating children with new onset of seizures in the emergency department. Epilepsia 2000;41:950�954. (14) Eisner RF, Turnbull TL, Howes DS, Gold IW. Efficacy of a �standard� seizure workup in the emergency department. Ann Emerg Med 1986;15:33�39. (2) Reinus WR, Zwemer Jr. FL, Fornoff JR. Seizure patient selection for emergency computed tomography. Ann Emerg Med 1993;22:1298�1303. (6) Warden CR, Brownstein DR, Del Beccaro MA. Predictors of abnormal findings of computed tomography of the head in pediatric patients presenting with seizures. Ann Emerg Med 1997;29:518�523. (15)

43. Reference Pesola GR, Westfal RE. New-onset generalized seizures in patients with AIDS presenting to an emergency department. Acad Emerg Med 1998;5:905�911. (5) Holmes JF, Palchak MJ, Conklin MJ, Kuppermann N. Do children require hospitalization after immediate posttraumatic seizures? Ann Emerg Med 2004;43:706�710. (12) Bui TT, Delgado CA, Simon HK. Infant seizures not so infantile: first-time seizures in children under six months of age presenting to the ED. Am J Emerg Med 2002;20:518�520. (16) Schoenenberger RA, Heim SM. Indication for computed tomography of the brain in patients with first uncomplicated generalised seizure. BMJ 1994;309:986�989. (7) For a complete list of references, please access the full guidelines at www.aan.com/guidelines

44. Questions/Comments

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