Transcript Practice Parameter or Technology Assessment: TITLE (an

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
© 2009 American Academy of Neurology
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© 2009 American Academy of Neurology
Presentation Objectives
• To reassess the evidence on use of
neuroimaging as a screening procedure for
altering management of the emergency patient
presenting with a seizure
• To present which clinical and historical
characteristics point to the need for a
neuroimaging study for such patients
• To present evidence-based recommendations
© 2009 American Academy of Neurology
Overview
•
•
•
•
Background
Gaps in care
AAN guideline process
Analysis of evidence, conclusions,
recommendations
• Recommendations for future research
© 2009 American Academy of Neurology
Background
• This reassessment is an update of the previous practice parameter
from 19961(1) and employs improved methodology for the
development of clinical practice guidelines.
• This practice parameter summarizes evidence for the usefulness of
performing an immediate neuroimaging procedure in the emergency
department on persons presenting with seizures.
• In this updated assessment, the authors specifically sought
evidence for the likelihood that neuroimaging would lead to an acute
or urgent change in management, and further, for characteristics of
patients likely to have an abnormal neuroimaging study in this
setting.
© 2009 American Academy of Neurology
Gaps in Care
• The methodology for the development of clinical
practice guidelines has improved since the
publication of the previous practice parameter.
• New research on this assessment topic has
become available since the publication of the
previous practice parameter.
© 2009 American Academy of Neurology
AAN Guideline Process
Clinical Question
Evidence
Conclusions
Recommendations
© 2009 American Academy of Neurology
Clinical Questions
• The first step in developing guidelines is to
clearly formulate questions to be answered.
• Questions address areas of controversy,
confusion, or variation in practice.
• Questions must be answerable with data
from the literature.
• Answering the question must have the
potential to improve care/patient outcomes.
© 2009 American Academy of Neurology
Literature Search/Review
Rigorous, Comprehensive, Transparent
Complete
Search
Review abstracts
Review full text
Select articles
Relevant
© 2009 American Academy of Neurology
AAN Classification of
Evidence
• All studies rated Class I, II, III, or IV
• Five different classification systems:
– Therapeutic
• Randomization, control, blinding
– Diagnostic
• Comparison to gold standard
– Prognostic
– Screening
– Causation
© 2009 American Academy of Neurology
AAN Level of
Recommendations
• A = Established as effective, ineffective, or harmful (or
established as useful/predictive or not useful/predictive)
for the given condition in the specified population.
• B = Probably effective, ineffective, or harmful (or
probably useful/predictive or not useful/predictive) for the
given condition in the specified population.
• C = Possibly effective, ineffective, or harmful (or
possibly useful/predictive or not useful/predictive) for the
given condition in the specified population.
• U = Data inadequate or conflicting; given current
knowledge, treatment (test, predictor) is unproven.
Note that recommendations can be positive or negative.
© 2009 American Academy of Neurology
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.
© 2009 American Academy of Neurology
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).
© 2009 American Academy of Neurology
Applying This Process
to the Issue
We will now turn our attention to the
guidelines.
© 2009 American Academy of Neurology
Clinical Questions
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?
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?
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?
© 2009 American Academy of Neurology
Clinical Questions, cont.
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)?
5. What factors are associated with an abnormal
neuroimaging study for patients presenting with seizure
in the emergency department?
© 2009 American Academy of Neurology
Methods
• Ovid Medline®
– 1966 to November 2004
– Relevant, fully published, peer-reviewed
articles
© 2009 American Academy of Neurology
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
© 2009 American Academy of Neurology
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.
© 2009 American Academy of Neurology
Literature Review
92 abstracts
15 articles
© 2009 American Academy of Neurology
Inclusion criteria:
- Relevant to the clinical
questions
- Limited to human subjects
- Bibliographies, metaanalyses, and articles
identified by panel members
Exclusion criteria:
- Review articles without
primary data, case reports,
articles for which the abstract
did not indicate that a
neuroimaging evaluation of
seizures in an urgent or
emergent setting was
performed
AAN Classification of Evidence
for Screening
• 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.
© 2009 American Academy of Neurology
AAN Classification of Evidence
for Screening, cont.
• 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.
© 2009 American Academy of Neurology
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?
© 2009 American Academy of Neurology
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.
© 2009 American Academy of Neurology
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).
© 2009 American Academy of Neurology
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?
© 2009 American Academy of Neurology
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.
© 2009 American Academy of Neurology
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).
© 2009 American Academy of Neurology
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?
© 2009 American Academy of Neurology
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.
© 2009 American Academy of Neurology
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).
© 2009 American Academy of Neurology
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?
© 2009 American Academy of Neurology
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)
© 2009 American Academy of Neurology
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).
© 2009 American Academy of Neurology
Analysis of Evidence
Question 5: What factors are associated
with an abnormal neuroimaging study
for patients presenting with seizure in
the emergency department?
© 2009 American Academy of Neurology
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)
© 2009 American Academy of Neurology
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).
© 2009 American Academy of Neurology
Gaps in the Evidence
•
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•
•
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.
© 2009 American Academy of Neurology
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.
© 2009 American Academy of Neurology
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.
© 2009 American Academy of Neurology
Reference
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2.
3.
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5.
6.
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© 2009 American Academy of Neurology
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© 2009 American Academy of Neurology
Reference
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For a complete list of references, please access the full
guidelines at www.aan.com/guidelines
© 2009 American Academy of Neurology
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© 2009 American Academy of Neurology