Slow‐Frequency Repetitive Transcranial Magnetic Stimulation in a Patient with Focal Cortical Dysplasia

Abstract

Summary: Purpose:To evaluate the effect of slow-frequency repetitive transcranial magnetic stimulation (SF-rTMS) on interictal epileptiform activity and seizure frequency in a patient with medically refractory partial seizures due to focal cortical dysplasia.Methods: A 9-cni circular coil was positioned over the area of cortical dysplasia. One hundred stimuli given at 0.5 Hz at 5% below motor threshold were given biweekly for four consecutive weeks. The EEG was recorded for 30 min before and after the first 100 stimuli. The number of seizures during the month of stimulation was compared with that of the month before stimulation.Results: Stimulation was associated with a 70% reduction in the frequency of seizures and a 77% reduction in the frequency of interictal spikes. No seizures occurred during stimulation.Conclusions: SF-rTMS was safe and well tolerated in this patient. The reduction in seizures and interictal spikes associated with SF-rTMS supports the concept of SF-rTMS-induced cortical inhibition. Key Words: Magnetic-StimulationEpilepsy-Treatment-Dy splasia.Partial seizures due to focal cortical dysplasia rarely respond to treatment with anticonvulsants (1 ). Although advances in the surgical treatment of such lesions have led to improved outcome, the probability of seizure freedom is substantially less than in other localizationrelated epilepsies (2). Other nonpharmacologic treatment options are needed for patients with epilepsy due to focal cortical dysplasia.Electrophysiologic methods of producing changes in cortical excitability became available with the advent of transcranial magnetic stimulation (TMS) ( 3 ) . TMS may be given as a single pulse or as a train of repetitive stimuli (r-TMS). r-TMS is further subdivided into fast frequency (FF r-TMS) for rates >1 Hertz and slow frequency (SF r-TMS) for rates <1 Hertz. Both frequencies induce immediate cortical suppression, but only FF r-TMS produces subsequent cortical excitation (4). Furthermore, FF r-TMS has side effects ranging from subject discomfort to seizure induction (5).In contrast, SF r-TMS is neither painful nor epileptoAccepted September 10, 1999. Address correspondence and reprint requests to Dr. M. Gruenthal at Department of Neurology, University of Louisville School of Medicine, 500 South Preston Street, HSC 113, Louisville, KY 40292, U.S.A. E-mail: MOgrueOl @athena.louisville.edu genic. A pilot trial of SF r-TMS-induced cortical inhibition was found to be effective in treating depression (6). A separate open, uncontrolled trial demonstrated similar result in depressed and schizophrenic patients (7). SF r-TMS reduces motor cortex excitability in humans (8) and reduces amygdala-kindled seizures in rats (9), suggesting a possible therapeutic role in localizationrelated epilepsy. We present a case in which SF r-TMS was used successfully in a patient with medically refractory partial seizures associated with focal cortical dysplasia.

Transcranial magnetic stimulation and brain atrophy: a computer-based human brain model study

“…When this current is applied repetitively, repetitive transcranial magnetic stimulation (rTMS), it can modulate cortical excitability, decreasing or increasing it, depending on the parameters of stimulation. Since its inception, researchers have proposed the use of TMS and rTMS to study and treat neuropsychiatric diseases, such as major depression George et al 2000;Martin et al 2003;Holtzheimer et al 2004;Rumi et al 2005), schizophrenia (Hoffman et al 2003;Lee et al 2005), Parkinson's disease (Mally and Stone 1999;de Groot et al 2001;Khedr et al 2003;Fregni et al 2004;Lefaucheur et al 2004), dystonia (Huang et al 2004), epilepsy (Tergau et al 1999;Menkes and Gruenthal 2000;Daniele et al 2003;Fregni et al 2005) and the acute or chronic sequels derived from stroke ). However, a fundamental question that needs to be addressed before the wide-spread use of TMS in clinical practice, is how the modification of brain anatomy and tissue properties caused by certain neuropsychiatric diseases can alter the effects of TMS.…”

Repetitive low-frequency stimulation reduces epileptiform synchronization in limbic neuronal networks

“…Over the last few years, several attempts have been made to use deep-brain electrical (Velasco et al, 2000a(Velasco et al, ,b, 2001Vonck et al, 2002;Yamamoto et al, 2002) or transcranial magnetic stimulation (Menkes and Gruenthal, 2000;Tergau et al, 1999) to abate seizures in patients presenting with epileptic disorders resistant to antiepileptic drugs, including mesial temporal lobe epilepsy (MTLE). These stimulating procedures have been often proved to be effective in reducing and/or abolishing both interictal and ictal discharges.…”

Experimental therapy of epilepsy with transcranial magnetic stimulation: lack of additional benefit with prolonged treatment

“…Lowfrequency rTMS appears to decrease cortical excitability for some time after stimulation sessions 14 . Recently, two studies have used low-frequency rTMS as a means of decreasing cortical excitability in epileptic patients 15,16 . Tergau et al 15 studied nine epileptic patients, using rTMS at a frequency of 0.3 Hz, in daily sessions, for a period of five days, and found a 20 % decrease in the mean weekly number of seizures in one patient; other three patients had a decrease between 20 and 50%, and another three subjects had a decrease of over 50%.…”

“…Comparisons were made between one month periods immediately before and after treatment. Menkes and Gruenthal 16 treated one patient with focal cortical dysplasia with bi-weekly low frequency (0.5 Hz) rTMS sessions for a period of one month. Daily seizure frequency was recorded for three months before rTMS sessions, during the month of treatment and for another month after the last experimental session.…”