A review of magnetoencephalography use in pediatric epilepsy: an update on best practice

ABSTRACT

Introduction: Magnetoencephalography (MEG) is a noninvasive technique that is used for presurgical evaluation of children with drug-resistant epilepsy (DRE).

Areas covered: The contributions of MEG for localizing the epileptogenic zone are discussed, in particular in extra-temporal lobe epilepsy and focal cortical dysplasia, which are common in children, as well as in difficult to localize epilepsy such as operculo-insular epilepsy. Further, the authors review current evidence on MEG for mapping eloquent cortex, its performance, application in clinical practice, and potential challenges.

Expert opinion: MEG could change the clinical management of children with DRE by directing placement of intracranial electrodes thereby enhancing their yield. With improved identification of a circumscribed epileptogenic zone, MEG could render more patients as suitable candidates for epilepsy surgery and increase utilization of surgery.

KEYWORDS:

• Drug-resistant epilepsy
• magnetoencephalography
• epileptogenic zone
• eloquent cortex mapping
• epilepsy surgery evaluation

Article highlights

• The high temporal and spatial resolution of magnetoencephalography (MEG) compared to EEG renders it a suitable technique for localizing the epileptogenic zone in children with drug-resistant epilepsy (DRE).

• MEG plays an important role for the presurgical evaluation of children with DRE, since extra-temporal epilepsy is more common in children than adults, and MEG has higher diagnostic accuracy in extra-temporal epilepsy than temporal epilepsy.

• MEG is beneficial for the evaluation of epileptogenic substrate such as focal cortical dysplasia (FCD), which is more common in children, and can guide second review of MRI to identify a subtle FCD that has been overlooked by the neuroradiologist.

• Data from MEG can be used to direct placement of intracranial electrodes, to enhance the yield from intracranial electrodes, and ultimately improve epilepsy surgery outcome.

• MEG could potentially improve identification of a circumscribed epileptogenic zone, and render more patients suitable candidates for epilepsy surgery, thereby increasing the utilization of surgery for the treatment of DRE.

• Another clinical application of MEG is for presurgical mapping of eloquent cortex, including sensory, motor, auditory, visual, and language.

• Localization or lateralization of memory function is not routinely done with MEG, but with improvement in MEG source localization algorithm to identify deep sources, its use for mapping memory function in the clinical setting could increase.

Children who require sedation can be administered intravenous or intranasal dexmedetomidine, as there is less suppression of epileptiform discharges with dexmedetomidine compared to propofol or midazolam.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded