Abstracts

RETURN TO ABSTRACT LISTING


E1944. Stereoelectroencephalography as an Emerging Adjunct to Seizure Localization in Pediatric Epilepsy
Authors
  1. Anthony Radosevich; Baylor University Medical Center
  2. Akshita Mehta; UT Southwestern Medical Center
  3. Deepa Sirsi; UT Southwestern Medical Center
  4. Daniel Veltkamp; UT Southwestern Medical Center
  5. Cory Pfeifer; UT Southwestern Medical Center
Background
Radiologists have long played a role in the pre-surgical approach to seizure localization. While non-invasive techniques have predominated, newer techniques for mapping ictal foci have evolved in recent years. This exhibit reviews traditional methods of seizure localization but supplements by explaining the roles of newer techniques in neuroradiology such as functional MRI, Diffusion Tensor Imaging (DTI), and Arterial Spin Labelling (ASL). The use of stereoelectroencephalography (SEEG) probe placement using multiple examples is also detailed.

Educational Goals / Teaching Points
Classical imaging techniques of seizure focus localization in the pediatric population are reviewed. The use of functional MRI, DTI, and ASL techniques to supplement the presurgical assessment process is addressed. Recent trends in avoiding general sedation at children's hospitals when appropriate are included. The process of SEEG placement and use is detailed. Correlation to seizure semiology and coordination with the neurology and neurosurgery teams is emphasized.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Children who fail anti-seizure medications or experience debilitating epilepsy require a formal seizure focus investigation. In coordination with electroencephalography (EEG), MRI at 3 Tesla is performed. This may require general sedation depending on the age and cooperativity of the patient, however, evolving recommendations favor eliminating general anesthesia for MRI if possible. This can be accomplished via practice MRI sessions and readily available support from child life specialists. DTI and ASL can be helpful in the initial MRI. Ictal nuclear medicine testing with a blood flow agent conjugated to Technetium 99m may localize to a seizure focus, and interictal positron emission testing can reveal areas of hypometabolism that may be helpful. When more invasive techniques are required, traditional mapping required a surface grid placement. Newer techniques involve transcalvarial SEEG probe provided that the skull thickness of the patient is appropriate. CT images of the head with probes in place are co-registered to high resolution thin-section MRI, and the contacts on each probe are localized by the radiologists. The SEEG is interpreted by the neurologist, and further planning in a multidisciplinary conference is conducted. The surgeon may then pursue surgical resection. Functional MRI can be performed to assist in assessing eloquent cortex which may affect surgical planning. In many cases, a pediatric neuropsychologist can assist in training the child prior to functional MRI to reduce patient motion and improve precision.

Conclusion
In coordination with the neurology and neurosurgery teams, knowledge of the approach to seizure localization is a changing and important concept for pediatric radiologists.