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Review
. 2023 May;270(5):2798-2808.
doi: 10.1007/s00415-023-11619-z. Epub 2023 Feb 15.

Neurological update: structural and functional imaging in epilepsy surgery

Katie Yoganathan #  1   2 , Naveed Malek #  3 , Emma Torzillo  4 , Menaka Paranathala  5 , John Greene  6
Affiliations
Review

Neurological update: structural and functional imaging in epilepsy surgery

Katie Yoganathan et al. J Neurol. 2023 May.

Abstract

Structural and functional imaging prior to surgery in drug-resistant focal epilepsy, has an important role to play alongside electroencephalography (EEG) techniques, in planning the surgical approach and predicting post-operative outcome. This paper reviews the role of structural and functional imaging of the brain, namely computed tomography (CT), magnetic resonance imaging (MRI), functional MRI (fMRI), single photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging in the preoperative work-up of people with medically refractory epilepsy. In MRI-negative patients, the precise localisation of the epileptogenic zone may be established by demonstrating hypometabolism on PET imaging or hyperperfusion on SPECT imaging in the area surrounding the seizure focus. These imaging modalities are far less invasive than intracranial EEG, which is the gold standard but requires surgical placement of electrodes or recording grids. Even when intracranial EEG is needed, PET or SPECT imaging can assist in the planning of EEG electrode placement, due to its' limited spatial sampling. Multimodal imaging techniques now allow the multidisciplinary epilepsy surgery team to identify and better characterise focal pathology, determine its' relationship to eloquent areas of the brain and the degree of interconnectedness within both physiological and pathological networks, as well as improve planning and surgical outcomes for patients. This paper will update the reader on this whole field and provide them with a practical guide, to aid them in the selection of appropriate investigations, interpretation of the findings and facilitating patient discussions in individuals with drug-resistant focal epilepsy.

Keywords: EEG; Epilepsy; FMRI; PET; SPECT; Surgery.

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Conflict of interest statement

KY, NM, ET, MP: Nothing to declare. JG has received a speaker’s fee from UCB and has received support to attend medical conferences from UCB, Eisai, GSK.

Figures

Fig. 1
Fig. 1
Cortical zones defined in the presurgical evaluation
Fig. 2
Fig. 2
Tc-99 m HMPAO pre-ictal brain SPECT scan (top image) an ictal scan (bottom image) section showing a focal area of hyperperfusion in the right temporal area (green arrows) suggesting a locus of seizure onset here
See this image and copyright information in PMC

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