Magnetoencephalographic spike sources associated with auditory auras in paediatric localisation-related epilepsy
I S Mohamed1, H Otsubo, E Pang
1Division of Neurology, The Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada.
Insights
Magnetoencephalography (MEG) identified clustered spike sources in the superior temporal gyrus in children with auditory seizures. These findings aid in localizing the epilepsy source, improving surgical outcomes.
Area of Science:
- Neuroscience
- Epileptology
- Medical Imaging
Background:
- Auditory auras are a manifestation of localisation-related epilepsy.
- Characterizing magnetoencephalographic (MEG) spike sources is crucial for epilepsy surgery planning.
Purpose of the Study:
- To characterize magnetoencephalographic spike sources in pediatric patients experiencing auditory auras and recurrent localisation-related epilepsy.
- To investigate the relationship between MEG findings and auditory-evoked magnetic fields (AEFs).
Main Methods:
- Retrospective study of six pediatric patients (ages 7-14) with auditory auras.
- Utilized scalp video electroencephalography, MEG, and in some cases, intraoperative or intracranial electroencephalography.
- Analyzed MEG auditory-evoked fields (AEFs) in four patients.
Main Results:
- All patients exhibited clustered MEG spike sources, predominantly in the superior temporal gyrus.
- MEG clusters were often near or encompassing the AEFs.
- Four patients underwent surgical resection of MEG-identified regions, with three remaining seizure-free at two years post-surgery.
Conclusions:
- MEG effectively clusters spike sources in the superior temporal gyrus in pediatric patients with auditory auras.
- These clustered MEG sources correlate with auditory-evoked magnetic fields and can indicate residual or recurrent epileptogenic zones.
- MEG-guided surgery shows promise for seizure control in this patient population.
Objective:
To characterise magnetoencephalographic spike sources in paediatric patients with auditory auras and recurrent localisation-related epilepsy.
Methods:
Six patients (four boys and two girls (ages 7-14 years) were retrospectively studied. All patients had auditory auras as part of their initial seizure manifestation, including four patients who underwent previous brain surgery. Scalp video electroencephalography and magnetoencephalography (MEG) were carried out in six patients, intraoperative electrocorticography in three patients and extraoperative intracranial video electroencephalography in one patient. MEG auditory-evoked fields (AEFs) were studied in four patients.
Results:
Three patients had elementary auditory auras, one had complex auditory aura and two had both complex and elementary auras. All six patients had clustered MEG spike sources with coexisting scattered spike sources. MEG clusters were localised in the superior temporal gyrus with surrounding scatters in four patients (two left and two right); two patients had scattered spikes in the superior temporal gyrus in addition to clustered MEG spike sources in the left inferior and middle frontal gyri or parieto-occipital region. AEFs were located within an MEG cluster in one patient and within 3 cm of a cluster in two patients. Surgical resection, including the regions of MEG clusters, was carried out in four patients. Three of four patients who had previous surgeries were seizure free at 2 years after excision of the MEG cluster region.
Conclusions:
MEG spike sources clustered in the superior temporal gyrus in six patients with auditory auras. These spike sources were in close proximity or seemed to engulf the magnetic AEF. Areas with MEG spike sources contained the residual or recurrent epileptogenic zone after incomplete cortical excision for lesional epilepsy.
