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Neuroimaging after First Seizure
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Neuroimaging after First Seizure
, Seizure Indications for Neuroimaging
Epidemiology
Incidence
: Neuroimaging in first non-febrile
Seizure Evaluation
identifies a structural
Brain Lesion
Adults: 33%
Infants <6 months: 50%
Techniques
Imaging Studies after first
Seizure
Step 1: Urgent
CT Head
(acute to exclude
Hemorrhage
)
Indicated urgently for at risk patients to exclude conditions that change acute management
Structural cause found in 17% of adults and 8% of children
New onset convulsive
Status Epilepticus
New
Focal Seizure
s
Persistently abnormal
Neurologic Exam
(or symptoms that do not resolve)
Failure to return to neurologic baseline or persistent neurologic deficits
New, non-
Febrile Seizure
in age <1 year old
Suspected
Trauma
tic cause (e.g. suspected
Child Abuse
or neglect)
Patient without risk factors for intracranial pathology
May wait for outpatient imaging typically with MRI Brain
Contrast needed only in HIV or cancer history where tumor or abscess is suspected
Step 2: Routine
MRI Head
(preferred for structural exam)
Higher efficacy than
Head CT
in identifying underlying
Brain Lesion
s
No radiation exposure (see
Cancer Risk due to Diagnostic Radiology
)
Even a greater concern in children in whom radiation exposure carries higher lifetime cancer risk
Indications
Adults
All adults should have Neuroimaging after First Seizure (per ACEP and AAN)
Timing of neuroimaging depends on presentation
At risk patients, should undergo urgent
Head CT
, followed by later MRI Brain
Stable patients may wait to undergo outpatient MRI Brain (if no contraindication for delay)
Urgent neuroimaging indications (typically
CT Head
)
Acute
Head Trauma
Age over 40 years
AIDS
Altered Mental Status
persists
Anticoagulation
Fever
Focal neurologic deficit of new onset
Headache
persists
Malignancy
Partial Seizure
(
Focal Seizure
)
Deferred outpatient neuroimaging indications (typically
MRI Head
with
Epilepsy
specific thin-sliced protocol)
Stable patient and
No urgent neuroimaging indications (see above) and
Reliable patient for follow-up and
Returned to baseline mental status during emergency department evaluation
Indications
Children
All patients under age 6-12 months (aside from simple
Febrile Seizure
)
Cognitive or
Motor Developmental Delay
EEG with primary
Generalized Epilepsy
Head Trauma
Malignancy
Brain Tumor
Prior
Cerebrovascular Accident
HIV Infection
Bleeding Disorder
or
Coagulopathy
Sickle Cell Disease
Hydrocephalus
Prior CNS surgery with shunt
Neurocutaneous Syndrome
(e.g.
Neurofibromatosis
, Tuberous Sclerosis)
Hemihypertrophy
Cysticercosis
exposure (e.g. travel to endemic regions)
Abnormal
Neurologic Exam
Focal neurologic deficits
Mental status changes persist
Partial Seizure
(
Focal Seizure
)
Postictal neurologic deficit that persists
References
Nocera, Valente, Amanullah (2018) Crit Dec Emerg Med 32(11): 3-9
Dayan (2015) Pediatrics 136(2): e351-60 +PMID:26195538 [PubMed]
Wilden (2012) Am Fam Physician 86(4): 334-40 [PubMed]
Harden (2007) Neurology 69(18): 1772-80 [PubMed]
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