Chapter 51 - Neuroimaging of epilepsy
Section snippets
Computed tomography (CT)
CT has the advantage of being available in most hospitals worldwide and has a relatively low operating cost. In addition, the logistics of CT make it easier for unstable patients as compared to MRI. CT can detect most tumors (except for some low-grade tumors), large arteriovenous malformations and extensive brain malformations, stroke, and infectious lesions. CT is sensitive for detection of calcified lesions and bone lesions, while MRI often misses these. CT has low sensitivity for detecting
When to perform an MRI in a patient with seizures
All patients with epilepsy should undergo an MRI, except those with very typical forms of primary generalized epilepsy (e.g., juvenile myoclonic epilepsy, childhood absence) or benign focal epilepsies of childhood with characteristic clinical and EEG features (e.g., benign epilepsy with centrotemporal spikes, early-onset childhood epilepsy with occipital spikes (Panayiotopoulos type)) and adequate response to antiepileptic drugs (AEDs) (Commission on Neuroimaging of the International League
How to perform an MRI in patients with epilepsy
The epileptogenic lesion may be detected using routine MRI protocols. However, routine MRIs often miss smaller or subtle lesions and are considered normal. Therefore, in these cases, an optimized epilepsy protocol with adequate spatial resolution and multiplanar reformatting is essential (Gaillard et al., 2011, Cendes, 2013).
A proper MRI investigation of patients with focal epilepsy requires the use of specific protocols, selected based on identification of the region of onset by clinical and
MRI in mesial temporal-lobe epilepsy
In MTLE, EEG findings, clinical history, and neuroimaging findings are important to define the diagnosis. Although there are other etiologies that cause TLE, HS is the most common pathologic substrate. MTLE with HS is often associated with a precipitating injury such as complex febrile seizures, birth trauma, meningitis, or head injury that happens in early life. A latent period of several years may precede dyscognitive seizures (previously known as complex partial seizures) (Cendes et al., 2014
Epilepsy due to neocortical lesions
MRI investigation will detect most common lesions causing neocortical epilepsy, which are: low-grade tumors, malformations of cortical development, posttraumatic and postischemic lesions, inflammatory infectious scars, cavernous malformations, and arteriovenous malformations. However, routine MRI may be unremarkable, particularly in some forms of malformations of cortical development. In these cases, multimodal imaging techniques can be useful for localizing suspected lesions. Among the
Focal cortical dysplasia
Refractory epilepsy, particularly in childhood, is often associated with malformations of cortical development, especially FCD. Many patients have seizures refractory to medication and are candidates for surgical treatment. However, not all patients with malformations of cortical development present with refractory epilepsy (Barkovich et al., 2012).
FCD is characterized by disorganization of the cortical lamination associated with bizarre (dysplastic) neurons or cells with eosinophilic cytoplasm
Diffusion tensor imaging and tractography
DTI data provide information regarding the direction of the diffusion of water in each voxel, which can be used to estimate the orientation of white-matter tracts. Based on this information, it is possible to trace major myelinated tracts (tractography), offering additional information for surgical approach; for example, it can be used for visualization of the optic radiation and for predicting visual field deficits after surgery (Winston et al., 2011). In addition, DTI allows other
Magnetic resonance spectroscopy (MRS)
Proton-MRS assesses neuronal integrity by quantifying the peak of N-acetyl-aspartate (NAA), a marker of neuronal integrity, usually by comparing its concentrations with choline or creatine peaks. Unlike MRI, SPECT, and PET techniques, the entire brain is not included in typical MRS measurements and often only a few relatively large voxels are sampled with proton MRS (Cendes et al., 2002). The relatively poor signal-to-noise ratio of proton MRS and the relatively long time required to obtain
Positron emission tomography
The role of PET, particularly using 18F-FDG, is well established. In addition to seizure focus localization, PET has been used for cognitive studies (now superseded by functional MRI), investigation of comorbidity, particularly psychiatric disorders, and investigations of neurotransmitter receptor binding. These studies may be important both for focus localization and understanding the pathophysiology of epilepsy. Coregistration with MRI has become standard for PET studies in epilepsy.
Single-photon emission computed tomography
SPECT has been proven as a useful tool in epileptogenic zone localization. The development of multimodal coregistration and also comparison of ictal SPECT images with a control group have ensured its clinical relevance. Ictal SPECT provides a unique window of opportunity to look at cerebral perfusion during seizure. Seizure activity dramatically increases brain metabolism and cerebral blood flow (CBF) in the epileptic focus during seizure initiation and propagation. Intravenous injection of
References (177)
Temporal lobe epilepsy: where do the seizures really begin?
Epilepsy Behav
(2009)- et al.
Increased neurokinin-1 receptor availability in temporal lobe epilepsy: a positron emission tomography study using [(11)C]GR205171
Epilepsy Res
(2011) - et al.
P-glycoprotein expression and function in patients with temporal lobe epilepsy: a case-control study
Lancet Neurol
(2013) - et al.
5-HT(1A) Receptor binding in temporal lobe epilepsy patients with and without major depression
Biol Psychiatry
(2007) - et al.
Interictal, unifocal spikes in refractory extratemporal epilepsy predict ictal origin and postsurgical outcome
Clin Neurophysiol Off J Int Fed Clin Neurophysiol
(2000) - et al.
Histamine H1 receptors in complex partial seizures
Lancet
(1993) - et al.
Relationship between bilateral temporal hypometabolism and EEG findings for mesial temporal lobe epilepsy: analysis of 18 F-FDG PET using SPM
Seizure
(2006) - et al.
Frontal lobe epilepsy: clinical characteristics, surgical outcomes and diagnostic modalities
Seizure
(2008) - et al.
Does SISCOM contribute to favorable seizure outcome after epilepsy surgery?
Epilepsia
(2007) Chronic encephalitis and epilepsy. Rasmussen's syndrome
(1991)
99mTc-D, L-hexamethylene-propyleneamine oxime (99mTc-HMPAO): basic kinetic studies of a tracer of cerebral blood flow
Cerebrovasc Brain Metab Rev
Mesial atrophy and outcome after amygdalohippocampectomy or temporal lobe removal
Ann Neurol
[11C](R)-PK11195 positron emission tomography imaging of activated microglia in vivo in Rasmussen's encephalitis
Neurology
Correlation between provoked ictal SPECT and depth recordings in adult drug-resistant epilepsy patients
Epilepsia
Brain damage from perinatal asphyxia: correlation of MR findings with gestational age
AJNR
MR in partial epilepsy: value of high-resolution volumetric techniques
AJNR
A developmental and genetic classification for malformations of cortical development: update 2012
Brain
Diagnosis of subtle focal dysplastic lesions: curvilinear multiplanar reformatting from three dimensional magnetic resonance imaging
Ann Neurol
In vivo P-glycoprotein function before and after epilepsy surgery
Neurology
Epilepsy surgery outcomes in temporal lobe epilepsy with a normal MRI
Epilepsia
Frequency, prognosis and surgical treatment of structural abnormalities seen with magnetic resonance imaging in childhood epilepsy
Brain
Revised terminology and concepts for organization of seizures and epilepsies: Report of the ILAE Commission on Classification and Terminology, 2005–2009
Epilepsia
Advances in MRI for ‘cryptogenic’ epilepsies
Nat Rev Neurol
Characteristics and surgical outcomes of patients with refractory magnetic resonance imaging-negative epilepsies
Arch Neurol
The clinicopathologic spectrum of focal cortical dysplasias: a consensus classification proposed by an ad hoc Task Force of the ILAE Diagnostic Methods Commission
Epilepsia
A neuropathology-based approach to epilepsy surgery in brain tumors and proposal for a new terminology use for long-term epilepsy-associated brain tumors
Acta Neuropathol
Cortical and subcortical networks in human secondarily generalized tonic-clonic seizures
Brain
Involvement of the basal ganglia in refractory epilepsy: an 18 F-fluoro-L-DOPA PET study using 2 methods of analysis
J Nucl Med
Seizure-related short-term plasticity of benzodiazepine receptors in partial epilepsy: a [11C]flumazenil-PET study
Brain
Alteration of the in vivo nicotinic receptor density in ADNFLE patients: a PET study
Brain
Cerebral metabolism and depression in patients with complex partial seizures
Arch Neurol
Refractory epilepsy: comparison of MR imaging, CT, and histopathologic findings in 117 patients
Radiology
Temporal lobe central benzodiazepine binding in unilateral mesial temporal lobe epilepsy
Neurology
Imaging inflammation in a patient with epilepsy due to focal cortical dysplasia
J Neuroimaging
MRI-negative PET-positive temporal lobe epilepsy: a distinct surgically remediable syndrome
Brain
Advances in neuroimaging: surgical localization
Epilepsia
Ictal SPECT in nonlesional extratemporal epilepsy
Epilepsia
Neuroimaging in investigation of patients with epilepsy
Continuum (Minneap Minn)
Magnetic resonance spectroscopy in epilepsy: clinical issues
Epilepsia
Epilepsies associated with hippocampal sclerosis
Acta Neuropathol
The Lennox-Gastaut syndrome: metabolic subtypes determined by 2-deoxy-2[18 F]fluoro-D-glucose positron emission tomography
Ann Neurol
Infantile spasms: I. PET identifies focal cortical dysgenesis in cryptogenic cases for surgical treatment
Ann Neurol
Surgery for intractable infantile spasms: neuroimaging perspectives
Epilepsia
Clinical and histopathologic correlates of 11C-alpha-methyl-L-tryptophan (AMT) PET abnormalities in children with intractable epilepsy
Epilepsia
α-[11C]-Methyl-L-tryptophan--PET in 191 patients with tuberous sclerosis complex
Neurology
Subtotal hemispherectomy in children with intractable focal epilepsy
Epilepsia
Frequent seizures are associated with a network of gray matter atrophy in temporal lobe epilepsy with or without hippocampal sclerosis
PLoS One
Imaging of malformations of cortical development
Epileptic Disord
Recommendations for neuroimaging of patients with epilepsy
Epilepsia
A pilot study in epilepsy patients using simultaneous PET/MR
Am J Nucl Med Mol Imaging
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