In the last half century, treatment options in the field of psychiatry have
increased exponentially with new developments and technologies. A new
class of pharmacological drugs was developed, electroconvulsive therapy
(ECT) protocols were optimized, and brain stimulation techniques were
invented. Most importantly, many Psychiatric symptoms now have
identifiable functional changes in specific regions and circuits in the brain.
Methods such as MRI, fMRI, positron emission tomography (PET) have
linked certain disorders and symptoms with certain diseases and loss of
function in brain regions.
This allowed techniques such as deep brain stimulation (DBS) or
transcranial magnetic stimulation (TMS-TMU) to target specific networks.
Targeting brain regions affected in a particular mental disorder has become
easy. One condition for which significant progress has been made is major
depressive disorder (MDD). MDD is a common disease and its lifetime
prevalence is 17%.
It is the second leading cause of disability according to World Health.
Patients diagnosed with MDD have irregularities in various brain regions,
including hypometabolism in regions such as the dorsolateral prefrontal
cortex (DLPFC), and abnormal overactivity in the cingulate cortex (ACC)
and amygdala, basal ganglia, and thalamus activity. Despite the availability
of psychotherapy and more than four classes and 30 different
pharmacological agents, the majority (32-52%) of MDD is still considered
resistant to treatment. These results necessitate new strategies for the
treatment of this disorder. Among the available treatments, stimulation
technologies, ECT, are still the most widely accepted. ECT (Electro
Convulsive Therapy) is an effective method with a remission rate of over
70%. However, inpatient treatment, which is associated with procedures
and side effects, is applied as a last option because it requires anesthesia.
It is the most stigmatized treatment available in psychiatry and a true 'last
resort' and is only used for those who are severely resistant to drugs or
TMS. (Deep Brain Stimulation) has also been shown to alleviate the
depressive state. Conventional TMS, which is a noninvasive technique in
drug-resistant MDD patients, does not have the above disadvantages. and
moderate MDD. To address these limitations, deep TMS (dTMS) was
introduced. dTMS includes all the benefits of TMS. There is no need for
hospitalization or anesthesia and negligible side effects. There is less focal
distribution of the electric field with the advantage of stimulating deeper
brain targets. Similar to the traditional TMS technique, dTMS uses short
Generally, trains provide a facilitating effect, inducing increased neuronal
excitability of transmitted pulses in high-frequency stimulation (>5 Hz).
Thus, certain brain regions of hypo- or hyper-activity can be modulated.
Conversely, however, conventional TMS coils (eg 8 or round) stimulate
targets directly up to ~1 cm below the surface of the Skull, dTMS can
simulate up to ~4 cm below the skull surface. This increased stimulation
depth is achieved due to multiple coils. These coils in the H-coil are
bundled together and improve the depth penetration of the electromagnetic
field without the need to increase it. Although deep stimulation can also be
performed with a large circular coil or a dual cone coil, their
electromagnetic field decays faster and much higher intensities must be
used to achieve significantly deep targets.
In the United States, dTMS uses the H1-coil, and different types of dTMS
are used. In Europe, dTMS using the H1-coil has started to be used for
unipolar depression, bipolar depression, negative symptoms and
post-traumatic treatment of schizophrenia, and OCD (Obsessive
Compulsive Disorder) and post-traumatic stress disorder (PTSD). Several
versions of H-coils are designed to target other brain networks.
It has started to be used in the treatment of Alzheimer's disease, chronic
pain, smoking cessation, obsessive compulsive disorder (OCD), autism,
Parkinson's disease, stroke rehabilitation and multiple sclerosis (MS).
In the United States, the dTMS device is only available with a prescription
from a doctor (usually a psychiatrist or a neurologist). Currently,
approximately 90% of all TMS treatments are administered in the treatment
form of dTMS.
Before administering dTMS to a patient, informed consent must be
obtained from the patient or legal guardian. In addition to explaining the
procedure in the process, there should be a description of the risks,
benefits and alternatives. Among the risks and potential side effects of
dTMS, headaches, facial pain, toothache, or neck pain can often occur
during the procedure but can also occur between procedures. Patients with
pre-existing epilepsy may be at risk of developing seizures. Despite these
potential risks, it is among the safest treatment methods. The advantage of
this method, which does not require outpatient anesthesia or
hospitalization, over classical TMS is its capacity to regulate deteriorated
structures in deep brain structures associated with diseases.