Into the island: a new technique of non-invasive cortical stimulation of the insula.

STUDY AIM

We describe a new neuronavigation-guided technique to target the posterior-superior insula (PSI) using a cooled-double-cone coil for deep cortical stimulation.

INTRODUCTION

Despite the analgesic effects brought about by repetitive transcranial magnetic stimulation (TMS) to the primary motor and prefrontal cortices, a significant proportion of patients remain symptomatic. This encouraged the search for new targets that may provide stronger pain relief. There is growing evidence that the posterior insula is implicated in the integration of painful stimuli in different pain syndromes and in homeostatic thermal integration.

METHODS

The primary motor cortex representation of the lower leg was used to calculate the motor threshold and thus, estimate the intensity of PSI stimulation.

RESULTS

Seven healthy volunteers were stimulated at 10 Hz to the right PSI and showed subjective changes in cold perception. The technique was safe and well tolerated.

CONCLUSIONS

The right posterior-superior insula is worth being considered in future studies as a possible target for rTMS stimulation in chronic pain patients.