What is the difference between unilateral and bilateral placement of electrodes in ect

The field produced with a small distance between electrodes will be more focal when directly covering less surface area, and less intense when a certain degree of shunt occurs on surface layers. On the contrary, BFT stimuli achieve greater psychopathological improvement at the cost of greater cognitive impairment due to more intense but less selective stimulation.

Subsequent work has not always confirmed these results, and a decade later, the also fundamental work of Kellner et al. It is not possible to affirm categorically that a position is always better, it being necessary to individualize the decision, applying this balance of efficacy-damage to each particular case, depending on the patient and the specific circumstances.

The importance attributed to electrical stimulus in ECT has varied throughout the history of the technique, and this remains very different, depending on the author.

The classic approach 10,71 considers that ECT produces its beneficial effect through a convulsion, provoked in different ways, currently by means of an electrical stimulus. The greater or lesser quality of this crisis will mean greater or less effectiveness, and that quality will depend, among other variables, on the characteristics of the electrical stimulus used. The alternative view 72—74 would argue that the electrical stimulus itself has a direct therapeutic effect as it has on undesired effects on the brain structures involved in the disorders treated.

The different techniques of direct stimulation, electrical or magnetic without a crisis, and which are currently on the increase, 75—77 would support this perspective. Evidently both alternatives are compatible and, in any case, the magnitude and quality of the electrical stimulus used are enormously important, either as a tool to provoke a therapeutic crisis, or as a direct actor of the effect. The total charge given to the patient in a stimulation we could say the electrons directed at the stimulated areas will depend on the intensity of the current that is, the charge that flows per unit of time, in milliamps [mA] and the duration of stimulation, a product in turn of the amplitude of the pulses administered in milliseconds [ms] , their frequency, and the total duration of the stimulus in seconds [s] :.

The charge necessary to cause a crisis in a given patient at a specific time depends on a large number of factors with different weighting, varying from age and sex to the patient's usual pharmacological treatment and the anaesthetics used, their hydration level, or the ventilation technique during anaesthesia, among many others. The current strategies to decide on this charge are essentially two: the anticipated charge calculation based on the variables with greater weight, and the progressive titration seeking the threshold.

Other methods described are mixed strategies where one starts from a certain basis, 81 or the benchmark charge. The methods of direct calculation of the charge start from the greater weighting attributed to some of the variables alluded to: essentially, age, but also sex and the position of the electrodes.

We have come to investigate complex statistical models that include numerous variables, 83,84 however in practice the approach of Abrams and others along the same lines still persists.

This perspective has in practice materialized as the method of Petrides and Fink in 86 who, in bilateral positions BFT or BF , propose giving a charge in mC equal to the patient's age, multiplied by 2. In devices with a charge indicator MECTA , this will be the charge in mC that is sought, then later deciding on the most suitable intensity, frequency, pulse amplitude and duration.

The psychiatrist has to predetermine the amplitude of the pulses given 0. If desired, the current versions can be individualized, setting the frequency, amplitude and duration of the stimulus manually, always with a fixed intensity of mA.

This method of calculating the charge will be quick because it directly proposes therapeutic charges; and simple, since it uses a single variable to calculate. We emphasize that this strategy directly calculates the anticipated charge as effective in obtaining a clinical response in a patient, not only for obtaining a convulsion. In contrast to the direct charge calculation method, the titration or empirical method is proposed. This seeks to identify the charge that a specific patient needs under certain conditions.

Given that the variables that influence it are very numerous and change over time, the pragmatic strategy will be to test charges until finding the appropriate one. In practice, this is a question of starting with deliberately low stimuli until a crisis greater than 15 s21 is reached.

The charge that was necessary for this will be called the convulsion threshold for that patient under those conditions. We find ourselves again up against the importance of the stimulus: it is not enough to exceed the threshold and obtain a crisis, and there are no minimum or sufficient crises durations for all patients. A sufficient stimulus to overcome the threshold and achieve a minimal response in EEG may not lead to a clinically effective response, especially in UL positions.

Its definition is arbitrary and based on modest evidence 31,80,89,90 which is also contradictory, 91 however it seems to be the best predictor of charge and response available to us. The range of variation between individuals is important, between and mC according to the studies. Overall, it appears that calculating the charge using titration would enable the stimulus to be individualized for a specific patient at a specific time and circumstances.

In contrast, at least theoretically, age-based formula calculations would, in principle, constitute an overdose in many young women and under-dose patients with UL 54 positions, as age is only one of the many variables that influence the patient's threshold. As a consequence, the main official guidelines on ECT practice 21,31 recommend the calculation of individualized charges using titration as a standard practice, although it is acceptable to calculate directly by age in situations of emergency or clinical severity, where it is not advisable to extend the response time, and the risk-benefit balance of high charges is acceptable.

The guides do not completely agree on the figure for multiplying the threshold to obtain a clinically effective charge. The UK's latest edition of the Royal College guide 21 indicates bilateral charges of at least 1. This is, indeed, a topic open to new research, as the cognitive impact benefit of UL ECT could be lost at over 4 times the threshold, 69, however not all patients will respond to these moderate charges.

Titration dosing presents objective drawbacks in daily practice, as it may delay the response by occasionally losing a first session in the calculation of the charge. In addition, it is possible that premature re-stimulations in the refractory period do not obtain a response.

Thus, in , Petrides et al. When multiplied by 1. Based on this, they firmly conclude that their method is openly superior to titration. Rasmussen questions these conclusions by proposing alternative titration strategies to those of the Consortium for Research in ECT CORE group, such as minor increases in the charge during titration, which minimize the final dose.

It could also be added that higher charges are not necessarily worse if they are what the patient needs in order to obtain a response. On the other hand, also in , Van Waarde et al. Their conclusion is that the methods of direct calculation of the charge are still legitimate. In a review of the publications by the CORE group between and , he stated that there is no justification for measuring the threshold, since his data does not show a variation in this throughout the sessions.

This absence of change would invalidate the threshold as a predictor of response. It should be noted that the threshold value derives from its ability to individualize the stimuli, regardless of their variation throughout the sessions. Increasingly more data is becoming available that indicates that overarching stimulus dose measurements are, as we said, an oversimplification, and that we will obtain different results by handling the stimulus variables that influence this charge.

The frequency varies the neuronal recovery time between stimuli, and the total duration will mean a different number of stimuli. The available devices make handling these parameters easier or less easy, depending. As we pointed out, Thymatron is designed to handle general charges, but if desired, it allows individualized adjustment options for frequency, amplitude and duration, but not intensity.

The individualization of the parameters in MECTA is, however, inevitable due to its design, with external controls laid down for this purpose. We shall briefly review the generally scarce information on these subjects, which it is undoubtedly necessary to deepen research into. Often these parameters are not even usually specified when describing the methodology of a ECT trial, and when considered, their analysis is often interfered with by other variables such as the position of the electrodes or the frequency and number of sessions.

As we have pointed out, stimuli of the same charge given over a longer period of time translate into lower convulsion thresholds. Therefore, by applying the expected charges over longer times during titration, it is possible to find lower thresholds; this will mean lower charges finally given, by multiplying by the constant corresponding to the position.

Although the clinical significance of this has not been demonstrated, 13 the usefulness of an action that obtains a crisis in high threshold situations, beyond the titration process, is evident. This lengthens the stimulation time while maintaining the same charge. Variations in the polarity of the neurons are related to the electrical field produced by the stimulus.

As we pointed out, the field varies depending on the size and position of the electrodes, and is very different depending on individual anatomical variables ; but it will also be directly proportional to the intensity parameter of the stimulus. Despite this, intensity is one of the least studied parameters of the stimulus, and sometimes it is considered without bearing in mind the other variables. However, the differences in the stimulated area—and therefore the neurons recruited—as a function of intensity, are very important, especially for UL positions, and more focal stimuli could be considered with lower intensities, which could result in less cognitive impairment.

On the other hand, we have data indicating that using high intensities makes it possible to specify lower threshold charges. The great advances made in the knowledge of the technique of stimulation in ECT, enables us to individualize action taken on a patient and their specific circumstances, and before the session to foresee the ingredients that will provide the best risk-benefit equilibrium.

No tools have been described to predict the number of sessions that will be necessary; the treatment is assessed and reconsidered after each session, and it is terminated when no further improvement is obtained. Although the usual practice regarding the interval between sessions in most countries is still to apply 3 sessions per week, individual adjustments of the decision are extended to between 2 and 3 sessions per week, depending on the technique used; the urgency of the response; and the risk of cognitive involvement.

However, some solid lines of investigation show that using high enough charges adjusted to suit the patient, the UL stimuli can be as effective as BFT, preserving the cognitive advantage. Other positions such as BF are not currently considered a usual alternative. Whether we consider the stimulus as a way to provoke the crisis which produces the therapeutic result, or if we defend the principle that this provokes effects directly, the scale and quality of the electrical stimulus is enormously significant.

Currently there are 2 strategies to decide on the charge that we will use on a patient: firstly, direct calculation in advance, based on the variables with greatest weight, and secondly, progressive titration, seeking the individual patient threshold. Direct calculation of the charge is based on the age variable to calculate the stimulus that is required.

By multiplying the age by a different constant, depending on the position of the electrodes 2. This calculation is performed automatically by certain models of stimulator Thymatron , designed in the light of this method, where the percentage of charge corresponding to the age for UL stimulation will be indicated directly on the dial, and half that for bilateral stimulation. Great variability of the precise charge in order to obtain a crisis in a particular patient at a given time and under specific conditions seems evident.

This is influenced by a large number of factors, in addition to age. As a consequence, the empirical or titration method was developed to determine the necessary stimulus, testing low charges until finding the appropriate one to obtain a minimum EEG crisis of 15 s, which will be termed threshold charge.

The indisputable logic of the proposal to individualize the charge by titration, as opposed to calculation based on a single variable such as age, has gradually prevailed in the main official guides on the practice of ECT, although this is an open topic and sometimes controversial, and both options are legitimate on the basis of our current knowledge, but always dependent upon the particular circumstances of the patient and the local environment where it is applied.

Finally, the general measures for the scale of the stimulus, such as the charge, are insufficient. It seems evident, and has been demonstrated, that supplying the same charge at different times, or with different intensity, amplitude or frequency of pulses, produces different results as regards the crisis obtained, its efficacy and its side effects.

Research on these parameters is scanty, and the clinical significance of the findings is not well defined. To sum up, it seems possible to exceed convulsion thresholds with lower charges, lengthening the total duration of the stimulus.

As regards intensity, there is little or no leeway for settings in the case of commercially available stimulators: all evidence, however, points to the fact that the area of the stimulus could be more focussed with lower levels of intensity, requiring fewer overarching charges at a higher intensity.

Regarding the frequency variable, the data points to greater effectiveness with low frequencies, which would obtain crises with lower charges. The findings on pulse amplitudes point in the same direction, where there is interest in researching the possible cognitive advantage of ultra-brief stimuli: less than 0. Although this line is open, the systematic use of ultra-brief pulses does not appear to be recommended due to less effectiveness, although it could be considered as an alternative in situations of clear cognitive risk.

Altogether, we find a progressive sophistication in the knowledge of stimulation used in ECT that, together with other fields within this technique, it is necessary to a reach consensus on, disseminate and adopt in our regular practice. This will be one of the bases of the process of dignifying and standardizing the treatment we are committed to.

The author has no conflict of interest to declare. Please cite this article as: Sanz-Fuentenebro FJ. Rev Psiquiatr Salud Ment Barc. Read more A pragmatic review. ISSN: Previous article Next article. Issue 1. Pages January - March More article options. Stimulus characteristics in electroconvulsive therapy. Download PDF. Francisco Javier Sanz-Fuentenebro a , b.

This item has received. Article information. One of the most complex aspects is the electrical stimulus, whose knowledge should be spread and put into practice. We also present two approaches to determine the ECT charge: stimulus titration versus age-based method; and the limitations of the summary metrics of charge, being necessary to expand our knowledge of the parameters that configure the stimulus: duration, current amplitude frequency and pulse width.

Electroconvulsive therapy. Palabras clave:. Terapia electroconvulsiva. Full Text. Introduction Electroconvulsive therapy ECT is a particularly effective treatment in the case of clearly defined indications, 1 still surrounded by a certain degree of stigma in our setting, and negatively affected by inefficient resource management, unequal access for patients, significant variability in rates and standards of application, and insufficient training of professionals.

Methodology The search results for articles published between and on the subject in Medline, Psychinfo, Embase and Cochrane originals have been thoroughly reviewed, as well as the main guides on the subject, including articles in English, French and Spanish, from original research texts to published cases, recommendations, consensuses or narrative reviews.

Results As with many other empirical medical treatments, the mechanism of action of ECT is not completely known, despite the enormous advances over the last few decades, 7 and the particular insistence with which knowledge of this technique is demanded. Number of sessions It is not possible to anticipate the number of sessions that will be required during acute treatment of ECT. Frequency of application The interval between sessions in acute treatment has been one of the topics in the process of change over recent years.

Placement of stimulation electrodes The optimal position of electrodes remains a debated issue, in close connection with advances in our knowledge of brain structures. Although 32—34 these were explored, and numerous positions are still being proposed that aim to minimize damage or increase effectiveness in situations of resistance, 35—37 there are 3 which are still regularly used: Bilateral frontotemporal BFT This is the classic position with the electrodes at the midpoint of the canthomeatal line on both sides.

General measurements of the size of the stimulus. Electroconvulsive therapy, practice and evidence. Br J Psychiatry, , pp. Vera, J. Sanz-Fuentenebro, M. Urretavizcaya, E. Verdura, V. Soria, E. Electroconvulsive therapy practice in Spain: a national survey. J ECT, 32 , pp. Sanz-Fuentenebro, I. Vera, E. Verdura, M. Soria, et al. Bernardo, M. Dignificando una terapia electroconvulsiva basada en la evidencia.

Rev Psiquiatr Salud Ment Barc , 8 , pp. Scott, J. The ECT handbook, 3rd ed. Mechanisms of ECT: reviewing the science and dismissing the myths. J ECT, 30 , pp. The ECT handbook. Celebrating 80 years of inducing brain seizures as psychiatric treatment. The seizure, not electricity, is essential in convulsive therapy: the flurothyl experience. Acta Psychiatr Scand, , pp. Peterchev, M.

Rosa, Z. Deng, J. Prudic, S. ECT stimulus parameters: rethinking dosage. J ECT, 26 , pp. Rodger, A. Scott, L. Is there a delay in the onset of the antidepressant effect of electroconvulsive therapy?. Husain, A. Rush, M. Fink, R. Knapp, G. Petrides, T. Rummans, et al. J Clin Psychiatry, 65 , pp.

Dunne, D. Systematic review and meta-analysis of bifrontal electroconvulsive therapy versus bilateral and unilateral electroconvulsive therapy in depression. World J Biol Psychiatry, 13 , pp. Segman, B. Shapira, M. Gorfine, B. Onset and time course of antidepressant action: psychopharmacological implications of a controlled trial of electroconvulsive therapy. Psychopharmacology Berl , , pp. Freeman, J. Hendry, G. National audit of electroconvulsive therapy in Scotland. Scottish Office, ,. Patterns of electroconvulsive therapy use in Spain.

Eur J Psychiatry, 21 , pp. Due for review: ECT Review Group. Efficacy and safety of electro-convulsive therapy in depressive disorders: a systematic review and meta-analysis, , pp. Loo, A. Kaill, P. Paton, B. The difficult-to-treat electroconvulsive therapy patient—strategies for augmenting outcomes.

J Affect Disord, , pp. Charlson, D. Siskind, S. Doi, E. McCallum, A. Broome, D. ECT efficacy and treatment course: a systematic review and meta-analysis of twice vs thrice weekly schedules.

Roche, J. Lope, H. Hughes, N. McCullagh, T. Larkin, L. Current Psychiatry. By Conrad M. Swartz, PhD, MD. Author and Disclosure Information Conrad M. PDF Download. Figure 1 Bitemporal electrode placement. In general, the more severely and urgently ill a patient is, the more likely he or she is to be treated initially with bilateral electrode placement.

Conversely, the more concerned a patient is about adverse cognitive effects, the more likely he is to be treated initially with right unilateral placement. Patients who do not show adequate response to unilateral elec- trode placement should generally be crossed over to bilateral electrode placement after approximately 6 treatments.

Modern ECT electrical stimuli consist of a series of brief pulses of electricity generated by the ECT device and delivered through the electrodes either metal or disposable adhesive placed on the scalp.

The total amount of electricity stimulus dose can be increased or decreased by manipulation of the following parameters:. The total amount of electrical charge delivered to the patient can be quantified in units of millicoulombs, conceptually analogous to a dose of a medication in milligrams. With unilateral placement, the degree to which electrical dose exceeds initial seizure threshold at subsequent treatments correlates with antidepressant outcome and cognitive effects.

Doses in the range of 6 times seizure threshold and higher have demonstrated efficacy equal to that of bitemporal placement. In current practice, using dose titration, at the second treatment and beyond, a multiple of the initial threshold stimulus is used to elicit seizures, typically approximately twice seizure threshold for bilateral or approximately 6 times threshold for right unilateral electrode placement.

Ongoing research will likely clarify whether this approach to stimulus dosing is optimal or whether more nuanced, or different, approaches will yield even better efficacy and tolerability. Manipulations of individual stimulus parameters may affect therapeutic and cognitive outcomes in ECT, independent of total electrical dose. The necessary pulse width to depolarize neurons is much shorter than that traditionally used on ECT devices, which is in the range of 0.

Sackeim and colleagues 8 randomly assigned depressed patients to ultrabrief 0. Electrode placement was further randomized to unilateral at 6 times threshold or bitemporal at 2. Cognitive adverse effects were markedly reduced in the ultrabrief pulse width groups. Enthusiasm in the ECT community for right unilateral ultrabrief pulse technique has grown, and it is now commonly used. A common clinical question is whether to use antidepressant medications concomitantly with ECT.

Sackeim and colleagues 12 randomly assigned patients to receive concomitant placebo, venlafaxine, or nortriptyline along with ECT. Both antidepressants improved remission rates compared with placebo; nortriptyline was slightly better than venlafaxine. Interestingly, anterograde and retrograde amnesia were less severe with nortriptyline than with venlafaxine or placebo.

Thus, the two most methodologically sound studies of concomitant antidepressant medications indicate that a TCA may enhance acute response rates with ECT. The ultrashort-acting barbiturate methohexital remains the anesthetic agent of choice in ECT because of its overall profile of characteristics that include predictable dosing, rapid onset, brief duration, only moderate anticonvulsant effect, and low cost.

Alternative agents include propofol, thiopental, etomidate, and ketamine. Ketamine is an older anesthetic medication that has generated enormous interest in psychiatry of late because of its intrinsic antidepressant activity.

Several randomized comparative trials have assessed ketamine in ECT, either as the primary anesthetic agent or as augmentation to another agent. Loo and colleagues 13 reported that 0. Electroconvulsive therapy stimulus parameters: rethinking dosage. Effectiveness of electroconvulsive therapy in community settings.

Biol Psychiatry. Radman T, Lisanby SH. Int Rev Psychiatry Abingdon, England. Article Google Scholar. Bifrontal versus right unilateral and bitemporal electroconvulsive therapy in major depressive disorder. Remifentanil added to propofol for induction of anesthesia can reduce reorientation time after electroconvulsive therapy in patients with severe mania.

Hemispheric asymmetry in the expression of positive and negative emotions. Neurologic evidence. Arch Neurol.

The effects of electroconvulsive therapy on quantitative electroencephalograms. Relationship to clinical outcome. A prospective, randomized, double-blind comparison of bilateral and right unilateral electroconvulsive therapy at different stimulus intensities. Treatment-resistant bipolar depression: a randomized controlled trial of electroconvulsive therapy versus algorithm-based pharmacological treatment.

Measuring retrograde autobiographical amnesia following electroconvulsive therapy: historical perspective and current issues. Retrograde autobiographical amnesia after electroconvulsive therapy: on the difficulty of finding the baby and clearing murky bathwater. Unilateral brief-pulse electroconvulsive therapy and cognition: effects of electrode placement, stimulus dosage and time. Ultra-brief pulse ECT in bipolar and unipolar depressive disorder: differences in speed of response.

Small JG. Efficacy of electroconvulsive therapy in schizophrenia, mania, and other disorders. Mania and other disorders. Manic symptoms: an indication for bilateral ECT. Biol Psychiat. Focal electrically administered seizure therapy: a novel form of ECT illustrates the roles of current directionality, polarity, and electrode configuration in seizure induction. Functional magnetic resonance imaging brain activation in bipolar mania: evidence for disruption of the ventrolateral prefrontal-amygdala emotional pathway.

Speed of response to threshold and suprathreshold bilateral ECT in depression, mania and schizophrenia. Electroconvulsive therapy ECT in bipolar disorder: a narrative review of literature. Asian J Psychiatr. Efficacy and safety of electroconvulsive therapy in depressive disorder: a systematic review and meta-analysis.

Youssef NA, Sidhom E. Download references. All authors read and approved the final manuscript. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Christopher C. You can also search for this author in PubMed Google Scholar. Correspondence to Christopher C. Reprints and Permissions. Abbott, C. Electroconvulsive therapy electrode placement for bipolar state-related targeted engagement. Int J Bipolar Disord 7, 11 Download citation.

Received : 21 December Accepted : 19 March Published : 04 May Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search all SpringerOpen articles Search.

Download PDF. Review Open Access Published: 04 May Electroconvulsive therapy electrode placement for bipolar state-related targeted engagement Christopher C. Methods We performed a literature search in the PubMed database. Conclusions While the heterogeneity of the studies makes comparisons difficult, important patterns included the reduced cognitive side effects, faster rate of response, and equivalent efficacy rates of the focal electrode placements right unilateral and bifrontal when compared to non-focal bitemporal placement.

Introduction Treatment resistance to pharmacotherapy in bipolar disorder is unfortunately common across all phases of the illness Thirthalli et al. Objectives of this review Efforts to develop more focal stimulation are contingent on identification of state-related anatomic regions for target engagement. Results: ECT electrode placement and bipolar phase We have summarized the included investigations and representative electric fields for bitemporal, bifrontal and right unilateral electrode placements single subject, milliampere pulse amplitude in Fig.

Full size image. Table 1 Electrode placement and bipolar mania Full size table. Table 2 Electrode placement and bipolar depression Full size table. Table 3 Electrode placement and bipolar mixed and bipolar catatonia Full size table. Table 4 Electrode placement and cognition Full size table. Discussion This review focused on the relationship of electrode placement on clinical outcomes in bipolar states. Conclusions Recent prospective ECT investigations with different bipolar states depressed, manic, mixed have assessed clinical outcomes with different electrode placements.

Acknowledgements Not applicable. Competing interests Dr. Availability of data and materials Included review articles are cited in references. Consent for publication The authors provide consent to International Journal of Bipolar Disorders for publication. Ethics approval and consent to participate Not applicable for review. Abbott View author publications. View author publications.

About this article.