Abstract
Background: Transcranial magnetic stimulation (TMS) is increasingly used for non-invasive functional mapping in preoperative evaluation for brain surgery, and the reliability of navigated TMS (nTMS) motor representation maps has been studied in the healthy population and in brain tumor patients. The lesions behind intractable epilepsy differ from typical brain tumors, ranging from developmental cortical malformations to injuries early in development, and may influence the functional organization of the cortical areas. Moreover, the interictal cortical epileptic activity and antiepileptic medication may affect the nTMS motor threshold. The reliability of the nTMS motor representation localization in epilepsy patients has not been addressed. Methods: We compared the nTMS motor cortical representation maps of hand and arm muscles with the results of invasive electrical cortical stimulation (ECS) in 13 patients with focal epilepsy. The nTMS maps were projected to the cortical surface segmented from preoperative magnetic resonance images (MRI), and the positions of the subdural electrodes were extracted from the postoperative low-dose computed tomography (CT) images registered with preoperative MRI. Results: The 3D distance between the average nTMS site and average ECS electrode location was 11 ± 4 mm for the hand and 16 ± 7 mm for arm muscle representation areas. In all patients the representation areas defined with nTMS and ECS were located on the same gyrus, also in patients with abundant interictal epileptic activity on the motor gyrus. Conclusions: nTMS can reliably locate the hand motor cortical representation area with the accuracy needed for pre-surgical evaluation in patients with epilepsy.
| Original language | English |
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| Pages (from-to) | 507-518 |
| Number of pages | 12 |
| Journal | Acta Neurochirurgica |
| Volume | 155 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 1 Mar 2013 |
| MoE publication type | A1 Journal article-refereed |
Funding
We would like to thank the staff contributing to the pre- and postoperative studies, diagnostics and data collection. Phil.Lic. Anne-Mari Vitikainen received a grant from the Finnish Cultural Foundation during the preparation of this manuscript. Ph.D. Pantelis Lioumis was supported by Helsinki University Central Hospital (EVO research funding) and the SalWe Research Program for Mind and Body (Tekes, the Finnish Funding Agency for Technology and Innovation, grant 1104/10).
Keywords
- Electrical cortical stimulation (ECS)
- Epilepsy
- Navigated transcranial magnetic stimulation (nTMS)
- Motor cortex localization
- TRANSCRANIAL MAGNETIC STIMULATION
- BRAIN-TUMOR SURGERY
- HUMAN CEREBRAL-CORTEX
- FUNCTIONAL LOCALIZATION
- ELECTRICAL-STIMULATION
- TMS
- EXCITABILITY
- SEIZURES
- COIL
- DEFORMATION