Ictal SPECT – Epilepsy Surgery Localisation — SCE Neurology MCQ

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HardClinical NeurophysiologyIctal SPECT – Epilepsy Surgery LocalisationSCE Neurology

A person with MRI-negative focal epilepsy is undergoing presurgical evaluation. Radiotracer is injected within seconds of electroclinical seizure onset and SPECT is later coregistered with interictal imaging. What does the study principally localise?

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Correct answer: A — The early ictal cerebral hyperperfusion region

The best answer is “The early ictal cerebral hyperperfusion region”. Ictal SPECT captures seizure-related regional blood-flow increase; subtraction and coregistration can contribute localisation when integrated with semiology, video-EEG, MRI and other presurgical evidence. “White-matter tract direction with diffusion anisotropy” is less appropriate because tractography uses diffusion MRI rather than perfusion tracer distribution “Interictal glucose hypometabolism measured by FDG” is less appropriate because FDG-PET measures metabolism and is generally an interictal study “The molecular identity of a cortical tumour” is less appropriate because perfusion does not provide tumour genotype “A replacement for concordant video-EEG and structural evaluation” is less appropriate because no single functional study replaces multidisciplinary concordance and may reflect early propagation

Reference: NICE NG217: Epilepsies in children, young people and adults. https://www.nice.org.uk/guidance/ng217/chapter/Recommendations