Behavioral and Neurophysiological Effects of Repetitive Transcranial Magnetic Stimulation on the Minimally Conscious State: A Case Study

Background. In 2007, Schiff et al reported a patient in a minimally conscious state (MCS) who responded to deep brain stimulation (DBS), but clinicians cannot predict which patients might respond prior to the implantation of electrodes. Methods. A patient in a MCS for 5 years participated in an ABA design alternating between repetitive transcranial magnetic stimulation (rTMS) and peripheral nerve stimulation. rTMS (condition A) involved the delivery of 10 trains of 100 stimuli at 20 Hz using a stimulator with a 70-mm figure-of-eight coil to elicit a contraction of the abductor pollicis brevis. Condition B used median nerve electrical stimulation. Results. After peripheral stimulation, the patient did not exhibit clinical, behavioral, or electroencephalographic (EEG) changes. The frequency of specific and meaningful behaviors increased after rTMS, along with the absolute and relative power of the EEG delta, beta, and alpha bands. Conclusion. These results suggest that rTMS may improve awareness and arousal in MCS. If these results are reproducible, rTMS may identify subgroups of MCS patients who might benefit from DBS.