Magnetic Seizure Therapy
Magnetic Seizure Therapy
Definition
Magnetic seizure therapy (MST) is a newer form of convulsive therapy under development since the late 1990s. Convulsive therapies generally induce a seizure, or convulsion, in a patient to provide improvement in mental illnesses, the chief among them being major depression . In addition to MST, convulsive therapies include electroconvulsive therapy (ECT), transcra-nial magnetic stimulation (TMS), deep brain stimulation, and vagus nerve stimulation .
Description
During MST, a generator produces multiple short bursts of electricity at a frequency of 50 to 100 Hz. This creates powerful magnetic fields within a wire coil shaped like a figure eight and attached to a paddle. A technician places the coil/paddle directly onto a patient’s forehead, near the forehead, or directly onto the scalp. Because the magnetic fields are not absorbed or scattered by the skull, lower frequency current than in ECT is sufficient; thus MST is safer than ECT because it uses less electricity. The magnetic fields reach down about an inch (2.5 cm) into the skull to produce electrical current affecting brain cells directly under the coil. These currents do not reach into areas beneath the cortex. However, current researchers are working to increase the distance reached to affect deeper-lying brain regions for greater positive results. The risks associated with MST are smaller than those associated with ECT, but include the standard risks associated with anesthetics. Additionally, memory loss and disruption of concentration and thinking are shorter and less severe.
The oldest convulsive therapy, ECT, has been the standard treatment for medication-resistant major depression for 70 years. However, ECT sends electricity to the brain and requires general anesthesia and muscle relaxants, subjecting patients to their associated risks. ECT causes memory loss for events close to the event of therapy and prior to therapy, and this memory does not return to all patients. To avoid the larger risks of anesthesia, muscle relaxants, and memory loss, researchers developed alternative convulsive therapies. A novel alternative, MST shows the most promise and was developed from TMS, which does not induce seizures at its generated electrical frequencies of 0.3 to 20 Hz.
TMS generates lower frequencies than required by ECT, so seizures do not occur. TMS is also focused
and more localized to avoid the larger brain areas accessed by ECT. As a result, TMS avoids memory loss. TMS does not require general anesthesia, so those associated risks do not exist. Magnetic seizure therapy comprises TMS administered at higher frequencies to induce seizures, at 50 to 100 Hz, but MST uses magnetic fields instead of electricity and these fields act directly on the brain. The skull does not absorb or scatter the magnetic fields, thus MST is more efficient than ECT. MST promises greater safety and diminished cognitive side effects over ECT.
Controversy
MST has been a point of debate since its inception. Its supporters report numerous well-documented successes, while its detractors insist that long-term patient improvement is possible only through seizures induced by ECT. However, researchers have found that MST seizures do not produce the large and intense side effects of ECT. MST produces fewer and shorter disruptions of memory, concentration, and orientation. Overall, MST may be safer and more efficient than ECT, produce fewer side effects, and perhaps reduce treatment costs.
Sarah Lisanby, MD, found that patients were able to remember their own names, current setting, current date, and current location much more quickly after receiving MST than after undergoing ECT. In fact, MST produced only 2 minutes of memory loss, while ECT caused memory loss for 13 minutes (over 6 times as long). MST also caused fewer problems with concentration. In task completion, patients finished a simple task in 4 minutes after receiving ECT, but in only 2 minutes after MST, and these differences were significant. Dr. Lisanby believes that most depressive patients can improve with TMS and without induced seizures, but that some depressed patients may need to undergo a seizure to improve and can benefit more from MST, because it offers fewer and smaller side effects than does ECT. Ongoing research may confirm these findings.
The controversy at present more often concerns MST versus TMS rather than MST versus ECT. According to the February 23, 2007, issue of the Harvard Mental Health Letter, 40% of medication resistant
KEY TERMS
Bipolar disorder —This disorder includes a cluster of four types, including bipolar I, bipolar II, cyclothymia, and bipolar disorder not otherwise specified (BD-NOS). All include periods of highs (manias) and lows (depressions) to varying degrees, durations, and frequencies.
Cortex —Cerebral cortex; outer gray matter layer of the cerebrum of the brain controlling sensation, voluntary movements, reasoning, thinking, and memory. The prefrontal cortex is at the front of the brain, just under the area behind the human forehead.
Deep brain stimulation —Electrodes are implanted into the brain to deliver constant low frequency electrical stimulation to a small part of the brain. Used in the treatment of Parkinson’s.
Deficit syndrome of schizophrenia —A condition of schizophrenia in which the patient exhibits affective flattening, attention impairment, lack of speech, lack of socializing, and lack of motivation.
ECT —Electroconvulsive therapy; the application of electrical current to the brain to induce a seizure in the treatment of major depression (most notably) and other mental illnesses. ECT requires general anesthetic and muscle relaxants. Side effects include memory loss, slowness to acquire new information, disruption of concentration, and, on occasion, brain edema (swelling).
Focal electrical stimulation —The application of electrical current during electroconvulsive therapy (ECT) or transcranial magnetic stimulation (TMS) to a localized area of the brain, rather than to a larger area.
Major depression —This disorder includes at least five or more of nine standard depressive symptoms for a period of longer than two weeks. Symptoms include sleeping problems or oversleep, marked appetite or weight change, fatigue, feelings of unworthiness, concentration problems, agitation, withdrawal from activities, feelings of hopelessness and helplessness, and suicidal ideation. Additional symptoms can include anger and features of psychosis.
Meta-analysis —A statistical method that combines the results from a number of different completed studies to provide a larger sample size and a stronger evidence base for conclusion than available in any of the single studies.
TMS —Transcranial magnetic stimulation; a method of electroshock therapy using magnetic fields and requiring no general anesthetic or seizure induction.
Vagus nerve stimulation —Implantation of a pacemaker-like unit that generates electrical pulses into the vagus nerve (the 10th cranial nerve). Used as an additional technique in the treatment of epilepsy.
depression cases improve with TMS, which induces no seizures. TMS may also reduce the time needed for psychiatric drugs to work. Findings are inconclusive regarding schizophrenia and post-trau matic stress disorder (PTSD), but TMS provides some improvement for obsessive-compulsive disorder (OCD). Further, the U.S. Food and Drug Administration (FDA) will decide in 2007 whether repetitive TMS (rTMS) will become an official standard alternative to ECT and MST treatments.
Applications
Depression, bipolar disorder, and schizophrenia
MST provides positive outcomes in treatment for a number of mental disorders. While the primary illness treated with MST is the same as for ECT, major depression, MST is also successful in cases of schizophrenia, bipolar depression, and bipolar mania. In 2005, Mitchell and Loo studied the safety and effectiveness of repetitive MST. They examined meta-anal-yses and individual patient reports and found that repetitive MST may be most effective in younger patients with no psychotic features and in depression that is not of the longest duration. Further, they found that some depression occurring in bipolar disorder responds better to repetitive MST than do unipolar depressions (those not part of a bipolar syndrome). The majority of depressed patients receiving repetitive MST suffer no side effects, or only slight discomfort in the stimulated scalp nerves and muscles or an occasional light headache. Sachdev, Loo, Mitchell, and Mahli also found in 2005 that repetitive MST produces significant positive outcomes in patients having the deficit syndrome of schizophrenia, which includes lack of talking, emotion, and motivation. This pilot investigation confirmed the previous existing research regarding MST as a successful treatment for schizophrenia.
Other applications
Harvard Medical School and Stanford et al. report that 30 ongoing controlled studies examining MST in the United States since October 2005 show positive outcomes. These studies look at MST as a treatment for mental illnesses and medical conditions having a mental health component. Thus far, these include major depression, schizophrenia, schizoaffec-tive disorder , bipolar disorder, post-traumatic stress disorder (PTSD), obsessive compulsive disorder (OCD), Tourette’s syndrome, Parkinson’s disease, stroke , and cerebral palsy. Additional applications may be found in future research.
Recent advances
In a 2006 meta-analysis, Loo, Schweitzer, and Pratt found that recent advances and alternative technical approaches have developed in ECT. They examined recent clinical trials , case reports, and research updates in ECT’s best practices and completed/ongoing research. Loo, Schweitzer, and Pratt found an increasing use of a number of alternative electrode placements useful in ECT, several variations in stimulus configurations, and two altogether new approaches that are successful. These new approaches are MST and focal electrical stimulation. The researchers found that MST may promise success and safety in treating a variety of mental illnesses but needs further research. This confirms the findings of the meta-analysis of Stanford et al. in 2005 that includes 69 separate sources and is currently approved for continuing education credit learning among physicians and researchers.
In addition to the above findings, Dr. Lisanby is currently researching two distinct forms of MST. One of these uses a wire coil to focus seizures in the pre-frontal cortex of the brain. The other form uses a coil to stimulate a broader brain area. This research is part of a wider study of MST effects compared with ECT effects in ongoing research at New York State Psychiatric Institute. Dr. Lisanby believes that MST can provide fewer side effects and better results than ECT for individuals with depression and a range of other mental illnesses.
Resources
PERIODICALS
Avery, David H., and others. “A Controlled Study of Repetitive Transcranial Magnetic Stimulation in Medication-Resistant Major Depression.” Biological Psychiatry 59.2 (2006): 187–94.
Harvard Medical School. “Electroconvulsive Therapy.” Harvard Mental Health Letter 23.8 (2007): 1–3.
Loo, Colleen K., Isaac Schweitzer, and Chris Pratt. “Recent Advances in Optimizing Electroconvulsive Therapy.” Australian and New Zealand Journal of Psychiatry 40.8 (2006): 632–38.
Loo, Colleen K, and Philip B. Mitchell. “A Review of the Efficacy of Transcranial Magnetic Stimulation (TMS) Treatment for Depression, and Current and Future Strategies to Optimize Efficacy.” Journal of Affective Disorders. 88.3 (2005): 255–67.
Mitchell, Philip B., and Colleen K. Loo. “Transcranial Magnetic Stimulation for Depression.” The Australian and New Zealand Journal of Psychiatry. 40.5 (2006): 406–13.
Sachdev, Perminder, Colleen Loo, Philip Mitchell, and Gin Malhi. “Transcranial Magnetic Stimulation for the Deficit Syndrome of Schizophrenia: a Pilot Investigation.” Psychiatry and Clinical Neurosciences. 59.3 (2005): 354–57.
Stanford, Arielle D., and others. “Magnetic Seizure Therapy and Other Convulsive Therapies.” Primary Psychiatry. 12.10 (2005): 44–50.
ORGANIZATIONS
The Association for Convulsive Therapy (ACT), 5454 Wisconsin Avenue, Chevy Chase, MD 20815. Telephone: (301) 951-7220. Web site: <http://www.act-ect.org/act/index.php>
Department of Psychiatry, Columbia University Medical Center, Harkness Pavillion, 180 Ft. Washington Avenue, New York, NY 10032. Telephone: (212) 305-6001. Web site: <http://www.cumc.columbia.edu/dept/pi/index.html>
New York State Psychiatric Institute, Columbia University Medical Center, 1051 Riverside Drive, New York, NY 10032. Telephone: (212) 543-6000. Web site: <http://www.nyspi.org>
Patty Inglish, MS