Transcranial magnetic stimulation in depression
by
Saba G, Januel D, Glikman J.
Psychiatre, assistant,
Unite de Recherche clinique, Secteur III,
Service du docteur Glikman,
EPS de Ville Evrard,
5, rue du Docteur Delafontaine, 93200
Saint-Denis, France.
Encephale 2002 Mar-Apr;28(2):169-75
ABSTRACT
Among the new therapeutic techniques in psychiatry, transcranial magnetic stimulation
(TMS) seems to bring a profit in the treatment of depressions. It uses the
principle of inductance to generate a magnetic current, which in turn activates
cortical neurons. Stimulation is highly focused and interests specific regions
of the cerebral cortex. This therapeutic technique is generally well tolerated.
Side effects are rare, the most hampering one is epileptic seizures. It is
favored by high frequencies (above 5 Hz) and arises mainly with patients
having a history of personal or family epileptic seizures. The first open
trials, quickly confirmed by controlled studies showed the efficiency of
TMS in depression. With depression, double blind randomized trials, using
high frequencies, stimulation of the left dorsolateral prefrontal cortex
give positive results with significant decrease of scores on depressive scales
applied to resistant and non resistant depressions. Some studies have stimulated
the right dorsolateral prefrontal cortex using low frequencies. The decrease
of scores is also significant on depressive scales. The modulating effect
of rTMS on cortical excitability of the brain justifies this distinction
between high and low frequencies, high frequencies having a facilitating
effect whereas low frequencies have an inhibitory effect.
Opposite effects of high and low frequency rTMS
on regional brain activity in depressed patients
by
Speer AM, Kimbrell TA, Wassermann EM,
D Repella J, Willis MW, Herscovitch P, Post RM.
Biological Psychiatry Branch,
National Institute of Mental Health,
Bethesda, Maryland 20895, USA.
Biol Psychiatry 2000 Dec 15; 48(12):1133-41
ABSTRACT
BACKGROUND: High (10-20 Hz) and low frequency (1-5 Hz) repetitive transcranial
magnetic stimulation (rTMS) have been explored for possible therapeutic effects
in the treatment of neuropsychiatric disorders. As part of a double-blind,
placebo-controlled, crossover study evaluating the antidepressant effect
of daily rTMS over the left prefrontal cortex, we evaluated changes in absolute
regional cerebral blood flow (rCBF) after treatment with 1- and 20-Hz rTMS.
Based on preclinical data, we postulated that high frequency rTMS would increase
and low frequency rTMS would decrease flow in frontal and related subcortical
circuits. METHODS: Ten medication-free, adult patients with major depression
(eight unipolar and two bipolar) were serially imaged using (15)O water and
positron emission tomography to measure rCBF. Each patient was scanned at
baseline and 72 hours after 10 daily treatments with 20-Hz rTMS and 10 daily
treatments with 1 Hz rTMS given in a randomized order. TMS was administered
over the left prefrontal cortex at 100% of motor threshold (MT). Significant
changes in rCBF from pretreatment baseline were determined by paired t test.
RESULTS: Twenty-hertz rTMS over the left prefrontal cortex was associated
only with increases in rCBF. Significant increases in rCBF across the group
of all 10 patients were located in the prefrontal cortex (L > R), the
cingulate gyrus (L >> R), and the left amygdala, as well as bilateral
insula, basal ganglia, uncus, hippocampus, parahippocampus, thalamus, and
cerebellum. In contrast, 1-Hz rTMS was associated only with decreases in
rCBF. Significant decreases in flow were noted in small areas of the right
prefrontal cortex, left medial temporal cortex, left basal ganglia, and left
amygdala. The changes in mood following the two rTMS frequencies were inversely
related (r = -.78, p <.005, n = 10) such that individuals who improved
with one frequency worsened with the other. CONCLUSIONS: These data indicate
that 2 weeks of daily 20-Hz rTMS over the left prefrontal cortex at 100%
MT induce persistent increases in rCBF in bilateral frontal, limbic, and
paralimbic regions implicated in depression, whereas 1-Hz rTMS produces more
circumscribed decreases (including in the left amygdala). These data demonstrate
frequency-dependent, opposite effects of high and low frequency rTMS on local
and distant regional brain activity that may have important implications
for clinical therapeutics in various neuropsychiatric disorders.
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