TMS in migraine

in Wassermann, E. M.; Epstein, C. M.; Ziemann, U. (Eds.) et al The Oxford Handbook of Transcranial Stimulation (2008)

Letters to the Editor: Controversies in headache

in Cephalalgia : An International Journal of Headache (2004), 24

Effects of repetitive transcranial magnetic stimulation on visual evoked potentials: new insights in healthy subjects

in Experimental Brain Research (2003), 150(3), 332-340

In a previous comparative study with migraineurs, we found in 24 normal subjects that the amplitude of the pattern-reversal visual evoked potential (PR-VEP) in the first block of 100 responses and its ... [more ▼]

In a previous comparative study with migraineurs, we found in 24 normal subjects that the amplitude of the pattern-reversal visual evoked potential (PR-VEP) in the first block of 100 responses and its habituation over 6 sequential blocks were significantly decreased after 1 Hz repetitive transcranial magnetic stimulation (rTMS), while 10 Hz rTMS had no significant effect. We report here our results on the reproducibility of the rTMS effect studied in ten of these subjects by repeating the recordings for each frequency three times on different days. We have also reanalysed the data obtained in 24 normal subjects, looking separately at the results in those stimulated at an intensity equal to phosphene threshold (group 1; n=14) and those stimulated at 110% of motor threshold because of unelicitable phosphenes (group 2; n=10). We finally determined the precise duration of the rTMS effect. Despite some interindividual variability, the effects of both rTMS frequencies on first block amplitude, habituation between first and sixth block and habituation slope over the six blocks were highly reproducible. The only difference between the two groups of subjects was the effect of 1 Hz rTMS on the second measured PR-VEP component. Whereas first block amplitude of the first P1-N1 component and habituation were decreased in both groups, such a decrease was found for the second P1-N2 component only in group 1 stimulated at phosphene threshold. The dishabituation of the N1-P1 component after 1 Hz rTMS was maximal at 15 min, but lasted up to 33 min, while that of P1-N2 disappeared after 3 min. There was a non-significant trend ( p=0.06) for a reduction of first block amplitude after 10 Hz rTMS in the total group of subjects, but no effect on habituation. The inhibitory effect of 1 Hz rTMS, which reduces in healthy controls both first block PR-VEP amplitude and habituation, probably by decreasing the preactivation excitability level of the underlying visual cortex, is thus reproducible and long lasting. Long trains of 10 Hz rTMS tend to attenuate reproducibly the cortical preactivation level in normal subjects, but they do not affect habituation at all, which contrasts with their effect in migraineurs, in whom, as previously reported, they significantly correct the habituation deficit. The absence of an effect of 1 Hz rTMS on PR-VEP P1-N2 in subjects stimulated at 110% of motor threshold may be explained by the deeper anatomical location of the cortical generators of this component and the lower stimulation intensity used. Taken together our results confirm that the effect of rTMS on the underlying cortex depends on several variables such as frequency, intensity and level of cortical preactivation. [less ▲]

Excitability of visual V1-V2 and motor cortices to single transcranial magnetic stimuli in migraine: a reappraisal using a figure-of-eight coil.

in Cephalalgia : An International Journal of Headache (2003), 23(4), 264-70

We used transcranial magnetic stimulation (TMS) with a figure-of-eight coil to excite motor and visual V1-V2 cortices in patients suffering from migraine without (MO) (n = 24) or with aura (MA) (n = 13 ... [more ▼]

We used transcranial magnetic stimulation (TMS) with a figure-of-eight coil to excite motor and visual V1-V2 cortices in patients suffering from migraine without (MO) (n = 24) or with aura (MA) (n = 13) and in healthy volunteers (HV) (n = 33). Patients who had a migraine attack within 3 days before or after the recordings were excluded. All females were recorded at mid-cycle. Single TMS pulses over the occipital cortex elicited phosphenes in 64% of HV, 63% of MO and 69% of MA patients. Compared with HV, the phosphene threshold was significantly increased in MO (P = 0.001) and in MA (P = 0.007), but there was no difference between the two groups of migraineurs. The motor threshold tended to be higher in both migraine groups than in HV, but the differences were not significant. In conclusion, this study shows that two-thirds (64.86%) of patients affected by either migraine type present an increased phosphene threshold in the interictal period, which suggests that their visual cortex is hypoexcitable. [less ▲]

Effects of repetitive transcranial magnetic stimulation on visual evoked potentials in migraine.

in Brain : A Journal of Neurology (2002), 125(Pt 4), 912-22

Between attacks, migraine patients are characterized by potentiation instead of habituation of stimulation-evoked cortical responses. It is debated whether this is due to increased or decreased cortical ... [more ▼]

Between attacks, migraine patients are characterized by potentiation instead of habituation of stimulation-evoked cortical responses. It is debated whether this is due to increased or decreased cortical excitability. We have studied the changes in visual cortex excitability by recording pattern-reversal visual evoked potentials (PR-VEP) after low- and high-frequency repetitive transcranial magnetic stimulation (rTMS), known respectively for their inhibitory and excitatory effect on the cortex. In 30 patients (20 migraine without, 10 with aura) and 24 healthy volunteers, rTMS of the occipital cortex was performed with a focal figure-of-eight magnetic coil (Magstim). Nine hundred pulses were delivered randomly at 1 or 10 Hz in two separate sessions. Stimulus intensity was set to the phosphene threshold or to 110% of the motor threshold if no phosphenes were elicited. Before and after rTMS, PR-VEP were averaged sequentially in six blocks of 100zztieresponses during uninterrupted 3.1 Hz stimulation. In healthy volunteers, PR-VEP amplitude was significantly decreased in the first block after 1 Hz rTMS and the habituation normally found in successive blocks after sustained stimulation was significantly attenuated. In migraine patients, 10 Hz rTMS was followed by a significant increase of first block PR-VEP amplitude and by a reversal to normal habituation of the potentiation (or dishabituation) characteristic of the disorder. This effect was similar in both forms of migraine and lasted for at least 9 min. There were no significant changes of PR-VEP amplitudes after 1 Hz rTMS in migraineurs and after 10 Hz rTMS in healthy volunteers, nor after sham stimulation. The recovery of a normal PR-VEP habituation pattern after high-frequency rTMS is probably due to activation of the visual cortex and the dishabituation in healthy volunteers to cortical inhibition. We conclude, therefore, that the deficient interictal PR-VEP habituation in migraine is due to a reduced, and not to an increased, pre-activation excitability level of the visual cortex. [less ▲]

Vagal nerve stimulation increases thermal pain tolerance in rats.

Conference (2001, May)