RESUMEN
OBJECTIVE: To use transcranial magnetic stimulation (TMS) to investigate the hypothesis that sleep deprivation increases cortical excitability in people with epilepsy. METHODS: We performed paired pulse TMS stimulation, using a number of interstimulus intervals (ISIs) on each hemisphere of 30 patients with untreated newly diagnosed epilepsy (15 idiopathic generalized epilepsy [IGE] and 15 focal epilepsy) and on the dominant hemisphere of 13 healthy control subjects, before and after sleep deprivation. RESULTS: Both hemispheres in patients with IGE and the hemisphere ipsilateral to the EEG seizure focus in those with focal epilepsy showed an increase in cortical excitability following sleep deprivation at a number of ISIs. This change in excitability was most prominent in the patients with IGE. Although there were minor changes after sleep deprivation in control subjects and the contralateral hemisphere in the focal epilepsy group seen at the 250-millisecond ISI, it was less than in the other groups. CONCLUSIONS: Sleep deprivation increases cortical excitability in epilepsy; the pattern of change is syndrome dependent.
Asunto(s)
Corteza Cerebral/fisiopatología , Epilepsia/fisiopatología , Privación de Sueño/fisiopatología , Adolescente , Adulto , Anciano , Electroencefalografía/métodos , Femenino , Lateralidad Funcional , Humanos , Masculino , Persona de Mediana Edad , Fase de Descanso del Ciclo Celular/fisiología , Factores de Tiempo , Estimulación Magnética Transcraneal/métodosRESUMEN
Transcranial magnetic stimulation (TMS) produces a cortical silent period (CSP) during a voluntary contraction. The duration of the CSP was used to assess the level of intracortical inhibition in patients with untreated idiopathic generalized epilepsy (IGE). Mean CSP duration was assessed at three TMS stimuli in 21 patients with IGE compared with 19 normal control subjects. Mean CSP duration was increased at all stimulus intensities, indicating that intracortical inhibition is increased in patients with IGE.
Asunto(s)
Epilepsia Generalizada/fisiopatología , Potenciales Evocados Motores/fisiología , Corteza Motora/fisiopatología , Adolescente , Adulto , Estimulación Eléctrica/métodos , Fenómenos Electromagnéticos , HumanosRESUMEN
Photic driving using a flashing strobe light was recorded via intracranial electrodes in two patients with occipital epilepsy being evaluated for surgery. The same technique was used to monitor the visual cortex intraoperatively. Visual evoked potentials (VEPs) were also obtained using the intracranial electrodes in one patient. Preoperative photic driving occurred in a separate location from the cortical areas producing ictal epileptiform activity. VEPs were located in the same site as photic driving. Photic driving was monitored throughout the resection and remained unaffected at the end of each procedure. Postoperative visual field testing in both patients showed preservation of central vision although some reduction in peripheral fields was seen. Intraoperative monitoring of the visual cortex using photic stimulation proved to be a reliable technique for preserving central vision during occipital lobe surgery.
Asunto(s)
Electroencefalografía , Epilepsia Parcial Compleja/fisiopatología , Epilepsia Parcial Compleja/cirugía , Monitoreo Intraoperatorio/métodos , Lóbulo Occipital/cirugía , Corteza Visual/fisiopatología , Campos Visuales , Adulto , Craneotomía/métodos , Electrodos Implantados , Epilepsia Parcial Compleja/patología , Potenciales Evocados Visuales , Femenino , Humanos , Lóbulo Occipital/patología , Lóbulo Occipital/fisiopatología , Estimulación Luminosa , Resultado del TratamientoRESUMEN
OBJECTIVE: Congenital brain lesions producing focal seizures may be accompanied by reorganization of the areas responsible for motor and sensory functions within the brain due to a phenomenon that has been termed "neuronal plasticity." This can be studied using functional MRI (fMRI) and transcranial magnetic stimulation (TMS). Using either method, the motor cortex can be localized noninvasively, but to date there have been few studies correlating the level of agreement between the two techniques. METHODS: We used fMRI and TMS to localize the motor cortex in a young woman with intractable focal seizures, congenital left arm weakness, and a dysplastic right hemisphere on MRI. RESULTS: There was excellent agreement in the localization of motor representation for each hand. Both were predominantly located in the left hemisphere. fMRI also showed an area of posterior activation in the right hemisphere, but there was no evidence of descending corticospinal projections from this site using TMS, direct cortical stimulation, and Wada testing. CONCLUSIONS: Functional MRI (fMRI) and transcranial magnetic stimulation (TMS) were successfully used to localize cortical motor function before epilepsy surgery. Each technique demonstrated migration of motor function for the left hand to the left motor cortex. After resection of the dysplastic right precentral gyrus there was no permanent increase in weakness or disability. The two techniques are complementary; fMRI indicates all cortical areas activated by the motor task, whereas TMS identifies only those areas giving rise to corticospinal projections.