Magnetic seizure therapy: development of a novel intervention for treatment resistant depression

A pilot study of magnetic seizure therapy for treatment-resistant obsessive-compulsive disorder

BACKGROUND

There is growing interest in the potential of neuromodulation options in treatment-resistant obsessive-compulsive disorder (OCD). Magnetic seizure therapy (MST), is a new treatment intervention in which generalized seizures are induced with transcranial magnetic stimulation. We conducted a pilot study to assess the efficacy and cognitive effects of MST in patients with treatment-resistant OCD.

METHODS

In an open-label pilot study, participants with treatment-resistant OCD and a baseline Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) scores of ≥16 were treated with up to 24 acute treatments. The primary clinical outcomes were clinical response (Y-BOCS score reduction ≥30%) and remission (final Y-BOCS score ≤8). A neurocognitive battery, the Quick Inventory for Depressive Symptoms-Self Report (QIDS-SR), the Beck Scale for Suicidal Ideation (SSI), and the Quality of Life Enjoyment and Satisfaction Questionnaire-Short Form (Q-LES-Q-SF) were also completed as secondary measures.

RESULTS

Ten participants with OCD who had not responded to medications or psychotherapy enrolled in the study and seven completed an adequate trial (defined as ≥8 treatments). MST was associated with minimal cognitive effects except for some decrease in autobiographical memory and no serious adverse effects. Only one participant met the predefined criteria for response, and none for remission. The baseline and endpoint Y-BOCS scores were not statistically different.

CONCLUSION

Overall, MST was not beneficial in a small group of patients with treatment-resistant OCD. At this time, other studies of MST for OCD are not warranted until different coil placements targeting other brain circuits can be proposed.

Magnetic Seizure Therapy: Towards Personalized Seizure Therapy for Major Depression

Magnetic seizure therapy (MST) is a noninvasive neuromodulation therapy under investigation for the treatment of severe neuropsychiatric disorders. MST involves inducing a therapeutic seizure under anesthesia in a setting similar to electroconvulsive therapy (ECT). To date, randomized controlled trials suggest that MST has similar antidepressant efficacy as ECT, but without significant cognitive adverse effects. Large scale clinical trials are currently underway to confirm these preliminary findings. So far, there has only been one study evaluating the clinical predictors of response to MST and more research is needed. This study found that patients with fewer episodes of depression and a positive family history of depression had a better response to MST. Overall, the ability of MST to focus the delivery of the electric field and the resultant seizure makes targeting seizure therapy to specific brain regions possible, and further research will be helpful in identifying personalized targets to maximize clinical benefit. In this review, we describe MST methodology and how it could be individualized to each patient. We also summarize the clinical and cognitive effects of MST and provide indications of which patients may be most likely to benefit. Finally, we summarize the studied neurophysiological predictors of response.

Comparable seizure characteristics in magnetic seizure therapy and electroconvulsive therapy for major depression

Electroconvulsive therapy (ECT) is highly effective for treatment-resistant depression (TRD); however, its use for less severe forms of depression is somewhat limited by a lack of control over current spreading to medial temporal lobe memory structures, resulting in various cognitive side effects. In contrast, magnetic seizure therapy (MST), which uses high frequency repetitive transcranial magnetic stimulation (rTMS) for local seizure induction, has been associated with reduced cognitive side effects. To assess whether different characteristics of seizures induced by both methods are responsible for the differences in neuropsychological side-effect profile, we studied seven TRD-patients undergoing both MST and ECT in an open-label, within subject, controlled crossover pilot study. Comparison parameters included seizure-related ictal characteristics, including motor activity, electromyogram (EMG), electroencephalogram (EEG), and postictal recovery and reorientation times.Our results showed no differences in motor activity or EMG and EEG characteristics, thus implicating similar electrophysiological processes in seizure induction with MST and ECT. In line with previous studies, we observed shorter postictal recovery and reorientation times following MST.The ictal characteristics of induced seizures were found similar with ECT and MST suggesting that the more focal seizure induction associated with MST may account for the more beneficial neuropsychological side effect profile of MST.

The use of ECT and MST in treating depression

Electroconvulsive therapy (ECT) has been used clinically since 1938. Its most common use is in the treatment of depression: first line treatment where rapid recovery is a priority, but more frequently as an effective treatment for patients who do not respond to pharmacological and psychological approaches. Whilst it is widely hailed as an effective treatment, concerns about its effect on cognition remain. The development of magnetic seizure therapy (MST) over the past decade has attempted to devise a therapy with comparable efficacy to ECT, but without the associated cognitive side effects. The rationale for this is that MST uses magnetic fields to induce seizures in the cortex, without electrical stimulation of brain structures involved with memory. MST has been used successfully in the treatment of depression, yet there is a dearth of literature in comparison with ECT. We present a systematic review of the literature on ECT (from 2009-2011) and MST (from 2001-2011).

Repetitive transcranial magnetic stimulator with controllable pulse parameters (cTMS)

We describe a novel transcranial magnetic stimulation (TMS) device that uses a circuit topology incorporating two energy-storage capacitors and two insulated-gate bipolar transistors (IGBTs) to generate near-rectangular electric field E-field) pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable-pulse-parameter TMS (cTMS) device can induce E-field pulses with phase widths of 5-200 µs and positive/negative phase amplitude ratio of 1-10. Compared to conventional monophasic and biphasic TMS, cTMS reduces energy dissipation by 78-82% and 55-57% and decreases coil heating by 15-33% and 31-41%, respectively. We demonstrate repetitive TMS (rTMS) trains of 3,000 pulses at frequencies up to 50 Hz with E-field pulse amplitude and width variability of less than 1.7% and 1%, respectively. The reduced power consumption and coil heating, and the flexible pulse parameter adjustment offered by cTMS could enhance existing TMS paradigms and could enable novel research and clinical applications with potentially enhanced potency.

A transcranial magnetic stimulator inducing near-rectangular pulses with controllable pulse width (cTMS)

A novel transcranial magnetic stimulation (TMS) device with controllable pulse width (PW) and near-rectangular pulse shape (cTMS) is described. The cTMS device uses an insulated gate bipolar transistor (IGBT) with appropriate snubbers to switch coil currents up to 6 kA, enabling PW control from 5 micros to over 100 micros. The near-rectangular induced electric field pulses use 2%-34% less energy and generate 67%-72% less coil heating compared to matched conventional cosine pulses. CTMS is used to stimulate rhesus monkey motor cortex in vivo with PWs of 20 to 100 micros, demonstrating the expected decrease of threshold pulse amplitude with increasing PW. The technological solutions used in the cTMS prototype can expand functionality, and reduce power consumption and coil heating in TMS, enhancing its research and therapeutic applications.

"Getting physical": the management of neuropsychiatric disorders using novel physical treatments

OBJECTIVE

To summarize and review the utility of physical interventions in the treatment of psychiatric disorders.

METHODS

A systematic review of the literature pertaining to novel physical interventions, namely, transcranial magnetic stimulation, deep brain stimulation, vagus nerve stimulation, and neurosurgery, was conducted using MEDLINE, EMBASE, and PSYCHLIT. Bibliographies of papers were scrutinized for further relevant references along with literature known to the authors.

RESULTS

Currently available physical interventions worldwide are reviewed with respect to efficacy, applications, and putative indications. Physical interventions have experienced a resurgence of interest for both the investigation of brain function and the treatment of neuropsychiatric disorders. The widespread availability of neuroimaging technology has advanced our understanding of brain function and allowed closer examination of the effects of physical treatments. Clinically, transcranial magnetic stimulation seems likely to have a role in the management of depression, and its use in other neuropsychiatric disorders appears promising. Following on from its success in the management of intractable epilepsy, vagus nerve stimulation is undergoing evaluation in the treatment of depression with some success in refractory cases. Deep brain stimulation has improved mood in patients with Parkinson's disease and may also relieve symptoms of obsessive-compulsive disorder. Neurosurgery has re-invented itself by way of increased technical sophistication, and although further assessment of its efficacy and clinical utility is still needed, its widespread practice reflects its increasing acceptance as a viable treatment of last resort.

CONCLUSION

It is clear that physical treatments are here to stay and "getting physical" offers a useful addition to the neuropsychiatrist's therapeutic armamentarium. However, like all new treatments these interventions need to remain under rigorous scientific scrutiny to determine accurately their immediate and long-term effects.

Seizure heralding functional recovery in a patient with apallic syndrome: A case report with retrospective-prospective observation

BACKGROUND

It has been suggested that there exists a close relationship between seizure discharges and functional recovery from brain injury, and that paroxysmal bombardment in late seizures may herald functional recovery or may "kick-start" recovery.

CASE REPORT

We report the case of a 52-year-old patient who, following a subarachnoid hemorrhage and multiple surgeries, experienced discernible apallic syndrome of long duration. His hospitalization is well documented. The patient underwent protracted, intense rehabilitation, but he remained in this prolonged state of loss of consciousness and behavioral passivity until he experienced a series of periodic seizures. Widespread improvement in his cognitive and functional abilities coincided closely with the seizure activity. The literature on this topic is reviewed.

CONCLUSION

This case confirms the close relationship between seizure discharges and functional recovery reported in preclinical literature.