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Motor cortex localization using functional MRI and transcranial magnetic stimulation
R A Macdonell1, G D Jackson, J M Curatolo
1Department of Neurology, Austin & Repatriation Medical Centre, Victoria, Australia.
Neurology
|October 26, 1999
Summary
Functional MRI (fMRI) and transcranial magnetic stimulation (TMS) successfully mapped motor cortex function in a patient with congenital brain lesions. Both techniques confirmed motor function migration, aiding epilepsy surgery planning.
Area of Science:
- Neuroscience
- Neurosurgery
- Medical Imaging
Background:
- Congenital brain lesions can cause focal seizures and neuronal plasticity, altering motor and sensory functions.
- Noninvasive techniques like functional MRI (fMRI) and transcranial magnetic stimulation (TMS) can localize the motor cortex.
- Correlation studies between fMRI and TMS for motor cortex localization are limited.
Observation:
- A young woman with intractable focal seizures, congenital left arm weakness, and a dysplastic right hemisphere was studied.
- fMRI and TMS were employed to map the motor cortex in this patient.
- The study aimed to assess the agreement between fMRI and TMS in localizing motor representation.
Findings:
- Excellent agreement was observed in localizing hand motor representation, predominantly in the left hemisphere.
- fMRI detected posterior activation in the right hemisphere, but TMS, direct cortical stimulation, and Wada testing found no descending corticospinal projections.
- Both fMRI and TMS demonstrated the migration of left-hand motor function to the left motor cortex.
Implications:
- fMRI and TMS are valuable tools for localizing cortical motor function prior to epilepsy surgery.
- The complementary nature of fMRI and TMS provides comprehensive information for surgical planning.
- Resection of the dysplastic right precentral gyrus did not result in permanent motor deficits, suggesting successful functional reorganization and surgical intervention.