A comparative analysis and critical review of two rTMS treatment durations in dogs with drug-resistant idiopathic epilepsy

Background: Repetitive transcranial magnetic stimulation (rTMS) is an effective, non-invasive management option for canine drug-resistant idiopathic epilepsy, but optimal stimulation protocols have not yet been established.

Hypothesis/objectives: The hypothesis is that treatment duration influences the therapeutic outcome of rTMS in dogs with drug-resistant idiopathic epilepsy. The objective is to compare and critically review the effect of different rTMS treatment durations on clinical outcomes in these patients.

Methods: Two previously published rTMS protocols (5-day vs. 3-day), using the same total number of pulses and a coil output of ≥ 70% were reviewed. The primary difference between the stimulation protocols did lay in the daily number of pulses administered. In the five-day protocol, 1620 pulses were delivered daily with a stimulation duration of approximately one hour, whereas the three-day protocol involved administering 2700 pulses per day, with the stimulation lasting around 1 h and 40 min. The monthly seizure frequency (MSF) and monthly seizure day frequency (i.e. days with seizures, MSDF) of the two study groups (5-day protocol, n = 12; 3-day protocol, n = 15) were compared in terms of the magnitude of change in seizure activity over a three-month period before and after rTMS stimulation.

Results: Both stimulation protocols were considered effective and resulted in an overall reduction in MSF. However, the 5-day protocol showed a significantly more pronounced reduction in MSF, with a mean decrease of 44%, compared to 19% in the 3-day protocol. The 3-day protocol had a lower responder rate than seen in the 5-day rTMS-group. Neither stimulation protocol did aggravate the progression of epilepsy.

Conclusion: rTMS is a safe treatment method, with no persistent adverse effects observed in any of the animals. The number of repetitions of the therapeutic intervention might influence the rTMS efficacy, which should be considered when establishing new rTMS protocols.