Electrical stimulation mapping of language with stereo-EEG

Epilepsy Behav. 2019 Oct:99:106395. doi: 10.1016/j.yebeh.2019.06.038. Epub 2019 Aug 15.

Abstract

Objective: We prospectively validated stereo-electroencephalography (EEG) electrical stimulation mapping (ESM) of language against a reference standard of meta-analytic functional magnetic resonance imaging (fMRI) framework (Neurosynth).

Methods: Language ESM was performed using 50 Hz, biphasic, bipolar, stimulation at 1-8 mA, with a picture naming task. Electrode contacts (ECs) were scored as ESM+ if ESM interfered with speech/language function. For each patient, presurgical MRI was transformed to a standard space and coregistered with computed tomographic (CT) scan to obtain EC locations. After whole-brain parcellation, this fused image data were intersected with three-dimensional language fMRI (Neurosynth), and each EC was classified as lying within/outside the fMRI language parcel. Diagnostic odds ratio (DOR) and other indices were estimated. Current thresholds for language inhibition and after-discharges (ADs) were analyzed using multivariable linear mixed models.

Results: In 10 patients (5 females), aged 5.4-21.2 years, speech/language inhibition was noted with ESM on 87/304 (29%) ECs. Stereo-EEG language ESM was a valid classifier of fMRI (Neurosynth) language sites (DOR: 9.02, p < 0.0001), with high specificity (0.87) but poor sensitivity (0.57). Similar diagnostic indices were seen for ECs in frontal or posterior regions, and gray or white matter. Language threshold (3.1 ± 1.5 mA) was lower than AD threshold (4.0 ± 2.0 mA, p = 0.0001). Language and AD thresholds decreased with age and intelligence quotient. Electrical stimulation mapping triggered seizures/auras represented patients' habitual semiology with 1 Hz stimulation.

Conclusions: Stereo-EEG ESM can reliably identify cerebral parcels with/without language function but may under detect all language sites. We suggest a 50-Hz stimulation protocol for language ESM with stereo-EEG.

Keywords: Epilepsy surgery; Functional brain mapping; Intracranial EEG; Language mapping.

MeSH terms

  • Adolescent
  • Brain / diagnostic imaging
  • Brain / physiology*
  • Brain / physiopathology
  • Brain Mapping / methods*
  • Child
  • Child, Preschool
  • Electric Stimulation / methods
  • Electroencephalography / methods*
  • Female
  • Humans
  • Language*
  • Magnetic Resonance Imaging / methods*
  • Male
  • Prospective Studies
  • Seizures / diagnostic imaging
  • Seizures / physiopathology
  • Seizures / surgery
  • Speech / physiology
  • Stereotaxic Techniques*
  • Young Adult