The International Neuromodulation Society defines neuromodulation (Neuro: Nerves, Modulation: Dynamic Change in the System) as “the alternation of nerve activity through delivery of electrical or electromagnetic stimulation, chemical agents, or light, to targeted sites in the brain or peripheral nervous systems.” There are numerous neuromodulation techniques that use direct or indirect electrical or electromagnetic stimulation, such as peripheral nerve stimulation, transcranial magnetic stimulation, transcranial direct current stimulation, and so on.
Various neuromodulation interventions are available and can be categorized as :
Direct : Direct application of electrical current is done either on the surface of the scalp (transcranial) or on the cortical surface of the brain or peripheral nerves (intracerebral). These techniques can be further divided into :
Invasive procedures : surgical Procedures where electrodes, pulse generators or other devices are implanted on the surface of the cortical brain or around peripheral nerves to provide electrical stimulation to a targeted site. examples include : Vagal Nerve Stimulation, Deep brain stimulation, cortical brain stimulation.
Non Invasive techniques : Procedures where application of electricual stimulation is done via a device like a coil over the surface of the scalp. Examples include ECT, tDCS (pl use full forms here)
Indirect : Application of rapidly changing magnetic field to the surface of the scalp that indirectly induces electrical currents in the target brain area. Examples include : TMS, Magnetic Seizure Therapy
TMS or Transcranial magnetic stimulation is a pain free, outpatient, non-invasive, neuromodulation technique used for treatment of various psychiatric as well as neurological disorders. TMS uses magnetic pulses to stimulate specific brain areas. It has been in use for various clinical reasons over more than four decades.
During this procedure, anaesthesia is not required, which is not only less distressing to patients, but the patient can also continue their daily routine immediately after the session.
Electroconvulsive therapy involves direct application of electrical current in general anaesthesia to induce generalised electrical stimulation of the neurons. While TMS involves induction of electrical charges by application of magnetic pulses to the scalp. Since no direct seizure is induced, nor is the entire brain involved in the stimulation target site, it precludes the need for general anaesthesia.
Each session can vary between 5 to 45 minutes depending on the medical condition, the protocol used and the brain areas involved. However, an approximate duration of session can be as follows:
Traditional rTMS: 15 to 45 minutes.
iTBS: -5 to 6 minutes.
TMS was first approved by the FDA (Food and Drug Administration, USA) in 2008 for the treatment of Major Depressive Disorder in adult patients who have failed to receive satisfactory improvement from prior antidepressant medication in the current episode. It has also been approved by NICE (or the National Institute of Health and Care Excellence, UK) in December 2015 for the treatment of severe depression.
Royal Australian and New Zealand College of Psychiatrists (RANZCP) recommends the use of rTMS for patients with non-psychotic depression who have failed one or more trials of standard antidepressant medications or psychological therapy.
Recently, FDA further cleared the use of Intermittent Theta Burst TMS in August 2018 for use in Major Depressive Disorder.
In addition to this, approval for Brainsway Deep Transcranial Magnetic Stimulation System for treatment of obsessive compulsive disorder (OCD) in August 2018, migraine in 2017 and cessation of smoking in 2019
The techniques can be used in the following conditions:
Obsessive compulsive disorder
Resistant auditory hallucination in Schizophrenia
Depression associated with parkinsonism
Post-traumatic stress disorder
Cessation of smoking
Existing evidence suggests that TMS is a safe and well tolerated modality of treatment. When administered in accordance with the latest safety guidelines published by Rossi et al, (insert link for the guidelines), the risk of seizures (one of the most acute adverse events of TMS) reduces to 8/100,000 patients with the majority occurring in high risk patients. Other adverse events include hearing problems like transient hearing artifacts which are easily avoidable with the use of a hearing protection aid, and mild local pain at the site of stimulation.
TMS Therapy is only associated with very mild discomfort if any experienced during session. The coil only produces a light tapping sound and a mild tapping sensation during therapy. Some patients might experience pain at the local site or headache following the session. The same is easily managed with over-the-counter analgesic medications.
Most medications are generally considered safe during the TMS intervention. However, some medications might affect the seizure threshold and necessitate a change in the protocol or the medication regimen. Kindly seek advice from your treating physician regarding the same.
The treatment is administered by a team of professionally trained physicians and device operators in accordance with the IFCN (International Fedration of Clinical Neurophysiology) guidelines. (Fried et al, 2021)
TMS Therapy does not require any hospitalization or sedation and the client can go back home or continue with the regular activities after the therapy session. However, if the patient is unable to commute regularly for the study, s/he can be admitted to the ward during the course of their sessions.
The sessions are provided free of any charge at our centre.
Adequate caution needs to be taken for patients with history of seizure, history of ECT (in the past 1 years), Cardiac pacemakers, or any other MRI incompatible metallic implants, defibrillator, cochlear implants, epilepsy, pregnancy, skull fracture, serious brain injury and neurosurgical procedure.
It is up to you to decide whether or not to take part. You are free to withdraw at any time and without giving a reason from the study.
All the information related to patient will be held confidential. Patient’s consent to participate in this study also includes consent to review all the medical records for the purpose of the study. Any release of information derived from these records to scientific organizations, medical journals, etc will be done without revealing any of your identification information.