Abstracts

Rationale: Repetitive transcranial magnetic stimulation (rTMS) is a safe and well-tolerated noninvasive method for focal cortical stimulation where small intracranial electrical currents are generated by a fluctuating extracranial magnetic field. When low frequency (≤1 Hz) rTMS is applied it leads to suppression of cortical excitability. Traditional rTMS coils are only capable of effectively stimulating outer cortical regions, however, the recently developed H-coil is capable of stimulating deeper structures, such as those often affected in temporal lobe epilepsy (TLE). We adapted the H-coil rTMS system to test the capacity of 1 Hz stimulation, to suppress seizures in TLE patients. A randomized-controlled trial is in progress. We present an interim review of the efficacy, safety and tolerability of the H-coil rTMS in patients with TLE.Methods: Verum rTMS was delivered in trains of 1800 pulses at 1 Hz, at intensity titrated to 120% motor threshold, with one train per day for 10 business days per subject. Sham rTMS delivered an audible and palpable stimulus without induced intracranial current. The following per-visit data were collected at baseline and subsequent to treatment: seizure diary, 20-minute resting EEG, and performance on the Wechsler Memory Scale (WMS) and the Children’s Memory Scale (CMS) (pediatric equivalent to WMS). We also collected patient safety and tolerability questionnaires and mini-mental examination (MME) scores.Results: 7 subjects completed the study. Interim efficacy analysis reveals significant effect of treatment (p=0.039) with 41% seizure frequency decrease in verum arm (n=4 patients) versus 19% seizure frequency increase in placebo arm (n=3 patients) relative to baseline. No serious adverse event such as atypical seizure, status epilepticus or epilepsy exacerbation occurred. Two instances of adverse events prompting withdrawal from the trial were: anxiety, before randomization (n=1 subject), and complaint of insomnia and memory deficits during sham treatment (n=1 subject). The most common other mild adverse events were transient headache (16% of session in placebo and 5% in verum) and neck pain (3% and 16%), which resolved in all instances within a few hours of stimulation. Neither placebo nor verum treatments adversely affected memory.Conclusions: Preliminary results suggest that 1 Hz rTMS with the H-coil may decrease seizure frequency in patients with TLE and support the safety of this intervention in a particularly vulnerable population.