STMs

Stochastic transcranial magnetic stimulation (sTMS) is a noninvasive brain stimulation modality that uses randomized or probabilistic pulse sequences, rather than fixed-frequency trains, to modulate cortical activity. By introducing variability into the timing and/or amplitude of stimulation, sTMS aims to influence neural plasticity and network dynamics in novel ways compared with conventional repetitive TMS (rTMS).

In practice, sTMS uses a coil placed over the scalp to deliver magnetic pulses. The inter-pulse intervals are drawn from predefined probability distributions within set safety limits, and pulse parameters such as intensity and duration may vary within prescribed ranges. Some protocols adjust stimulation in real time based on ongoing measurements, while others follow fixed stochastic schedules. The method is typically combined with neuronavigation to target specific brain regions.

Research on sTMS is exploratory and primarily conducted in laboratory and early clinical settings. Investigations have examined potential applications in mood disorders such as depression, tinnitus, chronic pain, and cognitive enhancement. Results are mixed and largely preliminary, with small sample sizes and varying study designs. As of now, sTMS is not broadly approved as a standard treatment and remains under investigation.

Safety considerations are similar to those of conventional TMS. Reported adverse effects include transient scalp discomfort, headaches, and rare seizures in predisposed individuals. Standard TMS safety guidelines apply, and patients with metal implants near the stimulation site or certain neurological conditions require careful assessment.

See also: transcranial magnetic stimulation, repetitive TMS, neuromodulation.