Manipulation of the sympathetic nervous system (SNS) with repetitive trans‐spinal magnetic stimulation in healthy adult humans

Abstract

Trans‐cranial magnetic stimulation (TCMS) is a non‐invasive, pain‐free technique used to stimulate and study the human brain and is able to elicit brief (< 5 s) changes in SNS activity. Use of TCMS to elicit longer‐term changes in SNS activity is problematic because magnetic stimulation of the cortex does not directly activate SNS control centers, and prolonged magnetic brain stimulation increases the risk of seizure. Repetitive trans‐spinal magnetic stimulation (rTSMS) represents a novel application of the same technology that avoids the risks associated with TCMS. We have examined the utility of rTSMS for modulation of SNS in adult humans. 32 adults (age: 18–47 yr) were randomly assigned to receive either rTSMS (1 Hz; n = 6, 10 Hz; n = 10, or 20 Hz; n = 8 at 50% intensity of stimulator output) or sham stimulation (SS; n = 8). Skeletal muscle SNS activity (MSNA; microneurography), R‐to‐R interval (RRint; ECG) and standard deviation of RRint (SDRRint; a marker of heart rate variability) were measured prior to, during, and post rTSMS or SS with the magnetic coil aligned with the spinous processes of the 6th and 7th cervical vertebrae. Compared with SS, rTSMS at any frequency did not affect any of the dependent variables: condition/time interaction ‐ MSNA: P = 0.89, RRint: P = 0.15, or SDRRint: P = 0.87. These preliminary data suggest that rTSMS does not influence SNS in adults.Support: NIA AG022053, CSU College of Applied Human Sciences