In order to test a new repetitive transcranial
magnetic stimulator, the Dantec MagPro, we administered transcranial magnetic stimulation
(TMS) at 1 Hz and 125% of motor threshold for an average of 204 s (until the coil
temperature reached 40 degrees C) and 20 Hz stimulation at 100% of motor threshold for 2 s
every minute for 10 min, on different days to 10 healthy volunteers. We stimulated 6 scalp
positions (primary motor area (M1) and sites 5 cm anterior and posterior on each
hemisphere) with an 8-shaped coil. We tested immediate and delayed memory, verbal fluency,
prolactin levels and EEG at the beginning of the study and after stimulation on each day.
No abnormalities were found. Motor evoked potentials evoked with 1 Hz stimulation
diminished progressively in amplitude, and 1 Hz stimulation of M1 caused inhibition
lasting at least 1 min in 3 of 4 subjects who were tested with 0.1 Hz stimulation before
and after the 1 Hz stimulation period. This did not occur with 20 Hz stimulation. Finger
tapping frequency was tested at the beginning of the study and after TMS at each scalp
site. Finger tapping rate data from 6 additional subjects who were stimulated in an
identical fashion with a different stimulator were also analyzed. There was an increase in
tapping rate after TMS which was independent of scalp site. This was most pronounced with
1 Hz stimulation at 125% of threshold and reached statistical significance in the hand
contralateral to the stimulation. The results of this study indicate that rTMS with the
MagPro stimulator is safe at specific combinations of intensity, frequency and train
duration.
When my office
lease expired at the end of 2004, I decided to turn it into a
"sabbatical" from my private practice. Many years ago, in my
grandfather's 89th year of life, he told me, "John, it is important
to smell the roses while you can still smell them." His life
gave living a very good reputation. It is also true that the
pursuit of that philosophy required my grandfather to to re-open his
assay office/ore market in Wickenburg, Arizona as a 75-year-old because
he had run a little short of retirement money. Thus, if blessed with his
luck and health, I'll be back.. --jjh
