---
title: "Pediatric Seizure"
docid: "3e2ea1fa-0651-45eb-bc1f-b072af8dd434"
authors:
- key: "b94c42b1-c572-4e72-ac48-bfe85989e2f3"
value: "Andrew T. Trout, MD"
- key: "0a00bb19-ed17-4500-8bae-c9463720a4fb"
value: "Nadeen K. Abu Ata, MD"
- key: "d2ed5cde-67ab-491a-963b-3c0f245d1fd8"
value: "Karol Cardenas, MD"
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name: "Nuclear Medicine"
slug: "nuclear-medicine"
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name: "Pediatrics"
slug: "pediatrics"
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name: "Central Nervous System"
slug: "central-nervous-system"
treeNodeId: "435fce7c-f625-479e-9355-82bab423f838"
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name: "Pediatric Seizure"
slug: "pediatric-seizure"
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category: "Nuclear Medicine"
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documentVersionId: "0d72d140-13c0-4727-843d-665ecaa6a0eb"
imageCount: 23
lastUpdated: "06/20/25"
pageDescription: "Pediatric Seizure"
pageKeywords: "Nuclear Medicine, Pediatrics, Central Nervous System, Pediatric Seizure"
pageTitle: "Pediatric Seizure | STATdx"
enhancedTitle: "Pediatric Seizure"
type: "DX"
references: true
breadcrumbs:
- "Nuclear Medicine"
- "Pediatrics"
- "Central Nervous System"
- "Pediatric Seizure"
---
# KEY FACTS
- ## Imaging
- Nuclear imaging is not part of routine evaluation of isolated seizures
- Plays important role in multidisciplinary/multimodality work-up of intractable epilepsy
- Nuclear imaging may identify structurally inconspicuous epileptogenic foci
- SPECT: Radiotracer deposition reflects regional cerebral blood flow
- Interictal: Epileptogenic focus appears as area of decreased radiotracer deposition (hypoperfusion)
- Ictal: Epileptogenic focus appears as area of increased radiotracer deposition (hyperperfusion)
- SISCOM may identify epileptogenic foci that are inconspicuous on visual assessment of ictal and interictal SPECT images
- F-18 FDG PET: Epileptogenic focus appears as area of hypometabolism (larger than epileptogenic focus)
- Statistical parametric mapping can help detect and confirm foci of hypometabolism
- MR is ideal modality to identify structural causes of seizure/epilepsy
- Mesial temporal sclerosis: Decreased volume, increased T2 signal in hippocampus
- Focal cortical dysplasia (FCD): Focal cortical thickening and increased T2 signal, blurring of gray-white junction
- ## Clinical Issues
- Most common cause of epilepsy
- Young: FCD
- Adolescent/young adult: Mesial temporal sclerosis
- Antiepileptic drugs are 1st line of therapy
- Surgical resection: Reserved for patients with intractable, focal epilepsy
# TERMINOLOGY
- ## Definitions
- Seizure: Clinical manifestation of aberrant neuronal electrical discharge(s) in brain
- Epilepsy: ≥ 2 unprovoked, afebrile seizures
# IMAGING
- ## General Features
- Imaging of isolated/acute seizures is generally structural (CT/MR) and reserved for patients with focal or complex seizures or focal neurologic signs
- Imaging is important component in management of epilepsy
- Structural imaging (CT/MR) often performed at diagnosis to exclude structural cause
- Multimodality imaging (including nuclear) plays substantial role in work-up of intractable epilepsy
- Work-up of intractable epilepsy is multidisciplinary/multimodality process
- Clinical assessment: History, seizure semiology
- Electroencephalography (EEG): Scalp and intracranial
- MR: Structural, ± functional
- Perfusion (SPECT) imaging
- Metabolic (F-18 FDG PET) imaging
- Magnetoencephalography
- ## Nuclear Medicine Findings
- Nuclear imaging not part of routine evaluation of isolated seizures
- May identify structurally inconspicuous epileptogenic foci
- **SPECT perfusion**
- Radiotracer deposition reflects regional cerebral blood flow
- Tc-99m hexamethylpropyleneamine oxime (HMPAO) and Tc-99m ethyl cysteinate dimer (ECD) most commonly used tracers
- Lipophilic, small molecules diffuse across blood-brain barrier
- ECD clears more rapidly from blood pool, has more linear extraction at high blood flow rates; less nonspecific scalp and soft tissue uptake than HMPAO
- High 1st-pass extraction, peak accumulation in ~ 2 min, no substantial redistribution
- Can image for at least 2 hours after injection without substantial loss of fidelity
- Interictal SPECT
- Epileptogenic focus appears as area of decreased radiotracer deposition (hypoperfusion)
- Ictal SPECT
- Epileptogenic focus appears as area of increased radiotracer deposition (hyperperfusion)
- Correspondence to epileptogenic focus depends on interval between seizure onset and injection; longer intervals allow more propagation to surrounding tissue
- Beware of pseudonormalization where hyperperfusion during ictus makes baseline hypoperfused focus appear symmetric to normal side
- Higher sensitivity than interictal SPECT for epileptogenic focus
- Subtraction ictal SPECT coregistered to MR (SISCOM)
- Means to compare ictal and interictal SPECT imaging and localize abnormalities to MR
- Foci of ictal hyperperfusion that correspond with interictal hypoperfusion appear as foci of activity on SISCOM
- May identify epileptogenic foci that are inconspicuous on visual assessment of ictal and interictal SPECT images
- **F-18 FDG PET**
- Interictal exam due to prolonged (~ 30 min) uptake of F-18 FDG
- If seizure occurs during uptake phase, may see hypermetabolism at epileptogenic focus and in surrounding brain
- Indirect marker of neuronal activity
- Epileptogenic focus appears as area of hypometabolism
- Area of hypometabolism is generally larger than epileptogenic focus
- Highest accuracy in temporal lobe epilepsy (TLE), less likely to identify epileptogenic focus in extratemporal epilepsy
- Contributes most in cases of structurally inconspicuous TLE or cases of suspected cortical dysplasia in children with apparent negative MR
- Higher sensitivity than interictal SPECT, especially in TLE (84% vs. 66% in one metaanalysis)
- Postprocessing with statistical parametric mapping (SPM) can help detect and confirm foci of hypometabolism
- SPM compares, on pixel by pixel basis, F-18 FDG uptake in patient to normal database to identify foci of abnormally decreased uptake
- In addition to identifying epileptogenic focus, it may provide prognostic information
- For example, in patients with unilateral temporal lobe epilepsy, presence of bitemporal glucose hypometabolism is associated with poor memory performance
- With both SPECT and PET imaging, may see corresponding downstream abnormality in cerebellar hemisphere opposite involved cerebral hemisphere
- Decreased radiotracer uptake on interictal SPECT and F-18 FDG PET
- Increased radiotracer uptake on ictal SPECT
- Hypometabolism of ipsilateral thalamus can be seen in cases of focal epilepsy (mostly in frontal and temporal cortex, medial temporal lobe epilepsy)
- **Other tracers**
- C-11 flumazenil: Binds CNS gamma-aminobutyric acid (GABA) receptors; GABA receptors are decreased in epileptogenic foci
- C-11 has short half-life (20 minutes), requiring onsite cyclotron (limiting its use)
- ## MR Findings
- Mesial temporal sclerosis: Decreased volume and increased T2 signal in mesial temporal structures, including hippocampal formation
- Resultant asymmetry in size of temporal horn of lateral ventricle
- Focal cortical dysplasia (FCD): Cortical thickening and increased T2 signal, extension of T2 signal to ventricle, blurring of gray-white junction
# DIFFERENTIAL DIAGNOSIS
- ## CNS Tumor
- May or may not be cause of seizures
- May appear as focus of hypo- or hyperperfusion on SPECT
- May appear as focus of hypometabolism on F-18 FDG PET if low grade
- ## Congenital Anomalies
- [Structural abnormalities: Heterotopic gray matter, abnormal sulcation, schizencephaly](/document/heterotopic-gray-matter/c88b27b7-d352-4231-b296-bd9d93b8c68b)
- May appear as focus of hypometabolism on FDG PET, even if not epileptogenic
- ## Tuberous Sclerosis
- Can be difficult to identify epileptogenic focus as majority of tubers are hypoperfused and hypometabolic
- Epileptogenic tubers generally show perfusion/metabolic abnormalities larger than area of structural abnormality
- ## Rasmussen Encephalitis
- Progressive inflammatory process involving unilateral cerebral hemisphere, generally with progressive cerebral atrophy
- Appears as large areas (lobar or hemispheric) of perfusion or metabolic abnormality
# PATHOLOGY
- ## Gross Pathologic & Surgical Features
- Mesial temporal sclerosis: Hard, shrunken hippocampus
- FCD: Firm, rubbery cortical focus
- ## Microscopic Features
- Mesial temporal sclerosis
- Variable distribution of pyramidal neuronal loss
- Gliosis
- FCD: Abnormalities in neuronal migration resulting in cortical dyslamination
- Type I: Abnormal cortical layering
- Ia: Abnormal radial migration of neurons with abundant microcolumns (> 8 neurons vertically arranged), most conspicuous in layer 3
- May see immature small neurons or hypertrophic pyramidal neurons outside of layer 5
- Ib: Abnormal tangential cortical layering
- May see no layering at all or abnormal layering of layers 2 &/or 4
- May see immature small neurons, hypertrophic pyramidal neurons outside of layer 5, or normal neurons with disordered dendrites
- Ic: Abnormal radial and tangential lamination
- Type II: Abnormal cortical layering **and**cytologic abnormalities
- IIa: No identifiable cortical layering except layer 1
- Dysmorphic neurons (enlarged cell body and nucleus, neurofilament accumulation in cytoplasm)
- IIb: No identifiable cortical layering except layer 1
- Dysmorphic neurons **and** balloon cells (large cell body, multiple nuclei, eosinophilic cytoplasm)
- Type III: Abnormal cortical layering associated with primary brain lesion (adjacent or in same lobe)
- IIIa: FCD associated with hippocampal sclerosis
- IIIb: FCD associated with tumors
- IIIc: FCD associated with vascular malformation
- IIId: FCD associated with any other lesion acquired in early life
# CLINICAL ISSUES
- ## Demographics
- ### Epidemiology
- Seizure
- Most common causes of acute seizures: Fever, infection, head injury
- Febrile seizures
- Usually occur between 6 months and 5 years of age
- Occur in 3-8% of children < 5 years
- 60% risk of recurrence
- Epilepsy
- Highest incidence in 1st year of life (~ 90-200 per 100,000)
- Prevalence higher in rural areas
- Risk factors
- Family history
- Prior febrile seizure: 2-7% develop epilepsy
- Most common causes
- Young: FCD
- Adolescent/young adult: Mesial temporal sclerosis
- Intractable epilepsy occurs in 20-30%
- ## Natural History & Prognosis
- Epilepsy subtypes: Current terminology
- Genetic abnormality without discrete structural abnormality
- Structural or metabolic
- Discrete structural epileptogenic lesion
- Many of these are genetic in etiology
- Metabolic condition leading to propensity for seizures
- Unknown cause
- FCD: Malformation of cortical development
- Secondary to insult (genetic, infectious, ischemic) during development
- Mesial temporal sclerosis
- Often secondary to insult (infection, trauma, febrile seizures) early in life
- ## Treatment
- Antiepileptic drugs
- 1st line of therapy
- Managing clinician will often try multiple agents and combinations of agents to achieve seizure reduction (or freedom) with minimum of side effects
- Ketogenic diet
- Vagal nerve stimulator
- Used in patients with drug-resistant epilepsy who are not candidates for resection
- Deep brain stimulator
- Used in patients with drug-resistant epilepsy who are not candidates for resection
- Surgical resection: Reserved for patients with drug-resistant, focal epilepsy
- Outcomes better if resection includes sites identified on SISCOM
- Outcome of surgery for FCD is better if lesion visible by MR
d21db106-d94e-4b66-b849-bb707a0aabd1
## References
# Selected References
1. [Ponisio MR et al: FDG-PET/MRI in the presurgical evaluation of pediatric epilepsy. Pediatr Radiol. 54(10):1589-602, 2024](http://www.ncbi.nlm.nih.gov/pubmed/?term=39123082%5Bpmid%5D)
1. [Guo J et al: Seizure outcome after surgery for refractory epilepsy diagnosed by (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET/MRI): a systematic review and meta-analysis. World Neurosurg. 173:34-43, 2023](http://www.ncbi.nlm.nih.gov/pubmed/?term=36746239%5Bpmid%5D)
1. [Juhász C et al: Utility of MRI, PET, and ictal SPECT in presurgical evaluation of non-lesional pediatric epilepsy. Seizure. 77:15-28, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=31122814%5Bpmid%5D)
1. [Wong-Kisiel LC et al: Challenges in managing epilepsy associated with focal cortical dysplasia in children. Epilepsy Res. 145:1-17, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=29803953%5Bpmid%5D)
1. [Manford M: Recent advances in epilepsy. J Neurol. 264(8):1811-24, 2017](http://www.ncbi.nlm.nih.gov/pubmed/?term=28120042%5Bpmid%5D)
1. [Mountz JM et al: Pediatric epilepsy: neurology, functional imaging, and neurosurgery. Semin Nucl Med. 47(2):170-87, 2017](http://www.ncbi.nlm.nih.gov/pubmed/?term=28237005%5Bpmid%5D)
1. [Duncan JS et al: Brain imaging in the assessment for epilepsy surgery. Lancet Neurol. 15(4):420-33, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=26925532%5Bpmid%5D)
1. [Miyata H et al: Surgical pathology of epilepsy-associated non-neoplastic cerebral lesions: a brief introduction with special reference to hippocampal sclerosis and focal cortical dysplasia. Neuropathology. 33(4):442-58, 2013](http://www.ncbi.nlm.nih.gov/pubmed/?term=23530853%5Bpmid%5D)
1. [Sidhu R et al: Pediatric seizures. Pediatr Rev. 34(8):333-41; 342, 2013](http://www.ncbi.nlm.nih.gov/pubmed/?term=23908360%5Bpmid%5D)
1. [Kim S et al: SPECT Imaging of epilepsy: an overview and comparison with F-18 FDG PET. Int J Mol Imaging. 2011:813028, 2011](http://www.ncbi.nlm.nih.gov/pubmed/?term=21785722%5Bpmid%5D)
1. [O'Brien TJ et al: Subtraction peri-ictal SPECT is predictive of extratemporal epilepsy surgery outcome. Neurology. 55(11):1668-77, 2000](http://www.ncbi.nlm.nih.gov/pubmed/?term=11113221%5Bpmid%5D)
1. [Won HJ et al: Comparison of MR imaging with PET and ictal SPECT in 118 patients with intractable epilepsy. AJNR Am J Neuroradiol. 20(4):593-9, 1999](http://www.ncbi.nlm.nih.gov/pubmed/?term=10319968%5Bpmid%5D)
1. [Devous MD Sr et al: SPECT brain imaging in epilepsy: a meta-analysis. J Nucl Med. 39(2):285-93, 1998](http://www.ncbi.nlm.nih.gov/pubmed/?term=9476937%5Bpmid%5D)
## Images
### Selected Images
, indicative of a seizure focus. Interpretation of functional brain imaging is aided by the fact that perfusion (SPECT) and metabolism (F-18 FDG) should be symmetric between the cerebral hemispheres and between the cerebellar hemispheres.](images/app.statdx.com_image_thumbnail_a299a4be-cf98-4fae-9b94-9d63f01d1923_annotated_true_size_900_quality_90_ec7f85c342f846b721ec871004ce8d2b4dd18fd3.jpg)
*Coronal interictal F-18 FDG PET in a 15-year-old with focal left temporal seizures on EEG and findings of left hippocampal sclerosis on MR shows diffuse hypometabolism of the left temporal lobe , indicative of a seizure focus. Interpretation of functional brain imaging is aided by the fact that perfusion (SPECT) and metabolism (F-18 FDG) should be symmetric between the cerebral hemispheres and between the cerebellar hemispheres.*
*Coronal interictal F-18 FDG PET in a 15-year-old with focal left temporal seizures on EEG and findings of left hippocampal sclerosis on MR shows diffuse hypometabolism of the left temporal lobe , indicative of a seizure focus. Interpretation of functional brain imaging is aided by the fact that perfusion (SPECT) and metabolism (F-18 FDG) should be symmetric between the cerebral hemispheres and between the cerebellar hemispheres.*
.](images/app.statdx.com_image_thumbnail_6a3b4a91-335c-4bd8-a946-b53291c24e5c_annotated_true_size_900_quality_90_8bb2173efa6473e1f78004c31d4ed6c3a907d838.jpg)
*Coronal FLAIR MR in a 16-year-old boy with intractable epilepsy shows an area of gliosis in the left parietal lobe related to remote trauma .*
*Coronal F-18 FDG PET in the same patient shows hypometabolism corresponding to the left parietal gliosis , as well as hypometabolism (relative to the right) of adjacent parietal lobe . This corroborates SPECT findings and suggests a seizure focus.*
*Interictal Tc-99m ECD SPECT in the same patient shows hypoperfusion corresponding to the left parietal gliosis and involving the adjacent parietal lobe .*
*Ictal Tc-99m ECD SPECT in the same patient shows hypoperfusion corresponding to the left parietal gliosis . The adjacent parietal lobe , however, is hyperperfused (relative to the right), reflecting seizure activity.*
*Sagittal T1 C+ MR in a 17-year-old girl shows a frontal dysembryoplastic neuroepithelial tumor (DNET) as a nonenhancing, low-signal lesion .*
*Sagittal F-18 FDG PET in the same patient shows focal hypometabolism associated with the DNET . In this case, the hypometabolism is reflective of both the low grade of this tumor and its epileptogenicity.*
*Axial T2 MR in a 12-year-old girl with epilepsy shows a right temporal focal cortical dysplasia (FCD), apparent as cortical and subcortical increased signal .*
*Axial F-18 FDG PET in the same patient shows hypometabolism associated with the FCD , supporting the epileptogenic nature of this lesion.*
. These findings support a right temporal localization of the seizure focus.](201da07a-12c7-4b99-9259-3fc7741fed9a)
*Coronal F-18 FDG PET in the same patient shows global hypometabolism of the right temporal lobe with more conspicuous hypometabolism of the hippocampus . These findings support a right temporal localization of the seizure focus.*
*Interictal Tc-99m ECD SPECT in a 2-year-old with intractable epilepsy shows enlargement of the left lateral ventricle and hypoperfusion of the left temporal lobe .*
in the overall hypoperfused left temporal lobe, suggesting a seizure focus.](6673c88d-d29f-470b-ac79-11c87d1a8101)
*Ictal Tc-99m ECD SPECT in the same patient shows an area of relative hyperperfusion in the overall hypoperfused left temporal lobe, suggesting a seizure focus.*
*Coronal SISCOM derived from the interictal and ictal SPECT and T1 MR in the same patient confirms an area of abnormal perfusion in the left temporal lobe , suggestive of a seizure focus. The left lateral ventricle is dilated due to extensive white matter loss.*
*Axial FLAIR MR in a 12-year-old with tuberous sclerosis and increasing seizure frequency shows multiple cortical tubers .*
*Axial interictal F-18 FDG PET in the same patient at the same level shows hypometabolism associated with the cortical tubers .*
*Axial interictal Tc-99m ECD SPECT in the same patient shows hypoperfusion corresponding to the cortical tubers .*
*Fused axial F-18 FDG PET and FLAIR MR in the same patient shows correspondence between areas of hypometabolism and the cortical tubers . Hypometabolism is similar in extent to the tubers. Areas of hypometabolism larger than underlying lesions can suggest an epileptogenic focus.*
*Coronal interictal F-18 FDG PET in a 7-year-old with intractable seizures shows hypometabolism in the right temporal lobe , particularly mesially in the hippocampal formation .*
*Coronal T2 FLAIR MR at the same level in the same patient shows abnormally increased signal in the right hippocampal formation in this child with mesial temporal sclerosis.*
### Additional Images
*Fused FDG PET MR in a 9-year-old boy with left lower extremity clonic movements shows a focal region of hypometabolism within the right paracentral lobule (left-foot motor control).*
*FDG PET MR postprocessing demonstrates same area of hypometabolism localized within the right paracentral lobule.*
*Coronal T2 MR in the same patient shows focal area of blurring of the gray matter-white matter junction and abnormal gyration in the right paracentral lobule, suggesting FCD (initially missed on MR).*
anterior to the expected location of the left paracentral lobule, suggesting motor remapping distant to FCD . Normal right foot motor activation centered about the left paracentral lobule 
.](8d7816c2-2143-4ab2-bf18-dc0e6634feaf)
*Left ankle flexion fMRI activated the right superior frontal gyrus anterior to the expected location of the left paracentral lobule, suggesting motor remapping distant to FCD . Normal right foot motor activation centered about the left paracentral lobule .*