Multimodality localization of the sensorimotor cortex in pediatric patients undergoing epilepsy surgery

Clinical article

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The gold-standard method for determining cortical functional organization in the context of neurosurgical intervention is electrical cortical stimulation (ECS), which disrupts normal cortical function to evoke movement. This technique is imprecise, however, as motor responses are not limited to the precentral gyrus. Electrical cortical stimulation also can trigger seizures, is not always tolerated, and is often unsuccessful, especially in children. Alternatively, endogenous motor and sensory signals can be mapped by somatosensory evoked potentials (SSEPs), functional MRI (fMRI), and electrocorticography of high gamma (70–150 Hz) signal power, which reflect normal cortical function. The authors evaluated whether these 4 modalities of mapping sensorimotor function in children produce concurrent results.


The authors retrospectively examined the charts of all patients who underwent epilepsy surgery at Seattle Children's Hospital between July 20, 1999, and July 1, 2011, and they included all patients in whom the primary motor or somatosensory cortex was localized via 2 or more of the following tests: ECS, SSEP, fMRI, or high gamma electrocorticography (hgECoG).


Inclusion criteria were met by 50 patients, whose mean age at operation was 10.6 years. The youngest patient who underwent hgECoG mapping was 2 years and 10 months old, which is younger than any patient reported on in the literature. The authors localized the putative sensorimotor cortex most often with hgECoG, followed by SSEP and fMRI; ECS was most likely to fail to localize the sensorimotor cortex.


Electrical cortical stimulation, SSEP, fMRI, and hgECoG generally produced concordant localization of motor and sensory function in children. When attempting to localize the sensorimotor cortex in children, hgECoG was more likely to produce results, was faster, safer, and did not require cooperation. The hgECoG maps in pediatric patients are similar to those in adult patients published in the literature. The sensorimotor cortex can be mapped by hgECoG and fMRI in children younger than 3 years old to localize cortical function.

Abbreviations used in this paper:BOLD = blood oxygen level–dependent; ECS = electrical cortical stimulation; fMRI = functional MRI; hgECoG = high gamma electrocorticography; SSEP = somatosensory evoked potential.

Article Information

Address correspondence to: Carter D. Wray, M.D., Division of Pediatric Neurology, Oregon Health & Science University, 707 Gaines Street SW, Mail Code CDRC-P, Portland, Oregon 97239. email:

Please include this information when citing this paper: published online June 8, 2012; DOI: 10.3171/2012.3.PEDS11554.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Motor cortex localization in Case 43 by ECS. Red dots denote localization.

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    Motor cortex localization in Case 43 by SSEP. Green dots denote localization.

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    Motor cortex localization in Case 43 by fMRI finger tapping. The colored area denotes localization.

  • View in gallery

    Motor cortex localization in Case 43 by increase in spectral power of hgECoG with movement. Blue dots denote localization.



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