Magnetic Seizure Therapy (MST) is a novel method of convulsive therapy using rapidly alternating strong magnetic fields. The clinical research reported to date concludes that it seems that MST offers the same clinical efficacy as ECT but without side effects. In research projects done so far the side effects often seen in ECT such as headache, nausea, dizziness or cognitive disorder have not been observed. Furthermore, a faster recovery of orientation compared to ECT patient has been reported.
The first use of therapeutic magnetic seizure induction in a psychiatric patient took place in Bern, Switzerland, in May 2000. Since then, a number of patients have gone through controlled studies. Although promising, researchers point out the need for further investigation in order to evaluate the antidepressant effect of more patients and establish MST as an effective tool for antidepressant therapy.
In the research projects completed so far the treatment procedure is very similar to a regular ECT treatment.
- Seizures were elicited under general anesthesia (propofol).
- The patient was oxygenated during anesthesia with 100 % O2.
- The motor activity of the right foot is assessed visually in order to track the duration of motor seizures and bilateral frontal-mastoid EEG recordings are obtained by an EEG device.
- Treatments are delivered with a magnetic stimulator (MagVenture MagPro MST) using the highly efficient “Twin Coil”.
- Stimulation repetition rate 100 pps. Number of pulses: 100-600 (duration 1-6s)
- Stimulation amplitude of 100%.
- During the stimulations, the center of the coil is placed at the vertex.
- The peak magnetic field induced above 2 Tesla at the coil surface.
- Two MST sessions per week.
The procedure and protocol used so far can probably be further optimized.
So far the main obstacle for MST has been a lack of sufficient power to create a seizure with certainty for every session. The MagPro MST makes research in this field more viable and a growing number of MagPro MST devices are in use worldwide for ongoing research projects.
Stimulation Coil - the MagVenture Twin Coil
To elicit a seizure a special magnetic coil which can utilize the high stimulator output is required and for maximum efficacy the Twin Coil for use with the MagPro MST consists of two individual coneshaped coils.
The position of each coil is easily adjustable to minimize the distance from the coil to the scalp and to ensure a deep penetration of the magnetic field.
Cognitive side effects limit the clinical use of electroconvulsive therapy (ECT), currently the most effective and rapid acting treatment for severe depression. Studies suggest that prefrontal cortical involvement may be important to preserve the efficacy of ECT, while seizure spread to the medial temporal lobes may be related to its amnesic side effects. However, the scalp and skull shunt the flow of electricity, limiting control over current spread with ECT. The Magnetic Fields used by MST enter the brain almost unimpeded, allowing enhanced control over the site of stimulation and seizure initiation compared to ECT. Magnetic Seizure Therapy (MST) involves the induction of a seizure under general anesthesia using high-frequency repetitive Transcranial Magnetic Stimulation. MST was developed to reduce the cognitive side effect burden of convulsive therapy through focal seizure induction in the prefrontal cortex. Preliminary results indicate that seizures induced with MST are more focal, result in less involvement of hippocampal and deep brain structures, and have a better acute side effect profile than those induced with ECT.