# Transcranial Direct Current Stimulation | Symptoms, Causes, Tests and Treatment | OSANG > tDCS (transcranial direct current stimulation) is a non-invasive neuromodulation treatment that modulates cerebral cortex activity by delivering micro-currents to the br… - Official page: https://osns.co.kr/en/encyclopedia/transcranial-direct-current-stimulation - Organization: OSANG Neurosurgery ## Page content Neuromodulation ## Transcranial Direct Current Stimulation Transcranial Direct Current Stimulation Transcranial direct current stimulation (tDCS) is a neuromodulation technique that modulates the excitability of cortical neurons by non-invasively delivering a weak direct current of 1 to 2 mA to the brain through electrodes attached to the scalp. ## At a glance tDCS (transcranial direct current stimulation) is a non-invasive neuromodulation treatment that modulates cerebral cortex activity by delivering micro-currents to the brain through scalp electrodes. Anode stimulation increases cortical excitability, and cathode stimulation acts to reduce it. Evidence is accumulating in the fields of depression, chronic pain, autonomic nerve control, and cognitive function improvement, and it can be performed in outpatient settings as it does not require anesthesia and has few side effects. - 01Definition and Overview - 02Principle and mechanism - 03Clinical indications - 04Effects on the autonomic nervous system - 05Treatment method - 06safety - 07Comparison of tDCS and TMS ## Definition and Overview Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that transmits a weak direct current of 1 to 2 mA through the skull to the brain cortex through electrodes attached to the scalp. It is being actively studied in neuroscience and clinical fields because it can change the excitability of neurons in the brain cortex without surgical procedures or anesthesia. tDCS has been studied since the early 20th century, but clinical research in its modern form began with the work of Nitsche and Paulus in 2000. Since then, clinical evidence has been accumulating in various areas such as depression, chronic pain, stroke rehabilitation, and cognitive function improvement. ## Principle and mechanism ### electrical principles A direct current of about 1 to 2 mA flows between two electrodes (anode, cathode) attached to the scalp. The electric current passes through the scalp, skull, and cerebrospinal fluid to reach the cerebral cortex. In reality, the current density reaching the brain is greatly attenuated as it passes through the skull. ### regulation of neuronal excitability - Anodal stimulation: Increases spontaneous firing rate by shifting the resting membrane potential of cortical neurons below the electrode toward depolarization. Cortical excitability increases. - Cathodal stimulation: Conversely, it causes hyperpolarization and reduces neuron firing rate. Cortical excitability is suppressed. ### synaptic plasticity The excitability changes of tDCS last for a certain period of time (tens of minutes to several hours) not only during stimulation but also after the end of stimulation. This is due to plastic changes similar to synaptic long-term potentiation (LTP) and long-term depression (LTD), which are associated with changes in NMDA receptors, calcium-dependent mechanisms, and brain neurotrophic factor (BDNF) expression. ## Clinical indications International clinical guidelines (2017), the level of evidence is confirmed in the following diseases: ### Established indications - Fibromyalgia: Bipolar stimulation of the primary motor cortex shows a significant effect in reducing pain. - Depression: Anodal stimulation of the left dorsolateral prefrontal cortex (DLPFC) is effective in improving depressive symptoms. In a meta-analysis, tDCS showed a significant reduction in depressive symptoms compared to placebo, and its effectiveness was also reported in drug-resistant depression. - Rehabilitation of motor function after stroke: Stimulation of the motor cortex of the damaged hemisphere promotes motor recovery. - Aphasia after stroke: Stimulation of the language center shows an adjuvant effect on language recovery. ### Indications under study - Chronic Pain and Neuropathic Pain - Control of autonomic function - Enhancing cognitive function and adjuvant treatment for Alzheimer's disease - Obsessive-compulsive disorder, PTSD - chronic fatigue syndrome - Cognition and Gait Function in Parkinson's Disease ## Effects on the autonomic nervous system tDCS stimulation of the left prefrontal cortex (DLPFC) or insula cortex can affect the central autonomic network (CAN), which is involved in regulating the autonomic nervous system. Studies have reported changes in heart rate variability (HRV) and blood pressure response after tDCS, and research on the mechanism for improving autonomic function is in progress. In particular, the insula is a key cortical structure in autonomic nervous regulation, and the hypothesis that tDCS stimulation of this area may be involved in regulating sympathetic-parasympathetic balance is being studied. ## Treatment method ### Instrument and electrode installation Standard tDCS devices supply a stable direct current of 1 to 2 mA. The electrode is a 35cm² square or circular sponge pad, and is sufficiently moistened with saline solution before the procedure to reduce contact resistance with the skin. ### target area Set the positions of the anode and cathode according to the purpose of treatment. For example, when treating depression, the anode is placed in the left DLPFC (F3 location, based on 10-20 EEG system), and the cathode is placed in the right superior superior parietal process. ### Procedure time and frequency One treatment takes 20 to 30 minutes, and the treatment process consists of 5 to 20 sessions (daily or every other day) depending on the disease and purpose. It can be performed as an outpatient procedure, and other treatments or cognitive training can be combined during the procedure. ## safety According to the 2016 international safety guidelines, tDCS performed within the recommended range (current density of 0.029 mA/cm² or less, total charge of 7.2 C or less) is safe without serious side effects. Minor side effects include skin erythema at the electrode site, tingling, and headaches. Difficulty concentrating and drowsiness may also appear temporarily. Absolute contraindications: intracranial metal implants (DBS electrodes, aneurysm clips), intracranial electrical stimulation devices. Relative precautions: epilepsy, pregnancy, scalp skin lesions, pacemakers. ## Comparison of tDCS and TMS | Item | tDCS | TMS | |------|------|-----| | Stimulation method | weak direct current | strong magnetic field induced current | | Mechanism of effect | Excitability regulation | Neuron direct firing | | Device size | Compact, portable | Large stationary | | Treatment time | 20~30 minutes | 30~40 minutes | | Noise/Inconvenience | Almost none | Hitting sound, scalp irritation | | Insurance Coverage | LIMITED | Partially applied | | Evidence of indication | Growing | Accumulating more evidence | ## Frequently asked questions ### Q01How does tDCS work? A weak direct current of 1 to 2 mA passes through the brain cortex through anode and cathode electrodes attached to the scalp. The area of the brain that receives anodal stimulation becomes prone to nerve cells being excited, while the area of the brain that receives cathodic stimulation becomes inhibited. This change persists for some time after stimulation through synaptic plasticity. ### Q02What is the difference between tDCS and TMS (transcranial magnetic stimulation)? TMS is a method of directly igniting nerve cells with a strong magnetic field, so the effect is quick and clear, but the equipment is large and expensive. Because tDCS only modulates the excitability of neurons (not inducing firing) with micro-currents, the equipment is small and easy to wear, and home-use devices are also being developed. The two methods have some overlap in indications, but each has different strengths. ### Q03What diseases is tDCS effective in? There is evidence in depression (especially drug-resistant), chronic pain (fibromyalgia, neuropathic pain), rehabilitation after stroke, improving cognitive function, and regulating autonomic imbalance. Studies have reported symptom improvement in more than 50% of patients with depression. ### Q04Doesn’t tDCS treatment hurt? tDCS may cause mild tingling, heat, or itching at the electrode area during the procedure, but most patients tolerate it well. No anesthesia is required, and it is possible to read a book or have a conversation during the procedure. To minimize skin irritation, use a saline-soaked sponge over the electrodes. ### Q05Is tDCS safe? When performed at appropriate intensity (less than 2 mA) and time (within 20 to 30 minutes), tDCS is a safe procedure with no serious side effects reported within international safety guidelines. Skin irritation, headache, and fatigue may occur in rare cases. Patients with epilepsy and those with intracranial metal implants require specialist consultation before the procedure. ### Q06How many treatments does it take to see the effect? For depression or chronic pain, an intensive course of treatment, usually 10 to 20 sessions, daily or every other day, is recommended. A single treatment may produce temporary effects, but repeated treatments are required for lasting effects. Depending on the treatment effectiveness and goals, consult with a specialist to determine the schedule. ## Related articles - Transcranial magnetic stimulation - Transcutaneous vagus nerve stimulation - Radiofrequency nerve block - deep brain stimulation This article provides general medical information and does not replace an individual diagnosis or treatment plan. Please seek a medical assessment if symptoms persist. ## Important notice This Markdown alternative helps search and AI tools understand the public page accurately. 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