Acute effect of electroconvulsive therapy on brain perfusion assessed by Tc99m-hexamethylpropyleneamineoxim and single photon emission computed tomography

Parsing the Network Mechanisms of Electroconvulsive Therapy

Electroconvulsive therapy (ECT) is one of the oldest and most effective forms of neurostimulation, wherein electrical current is used to elicit brief, generalized seizures under general anesthesia. When electrodes are positioned to target frontotemporal cortex, ECT is arguably the most effective treatment for severe major depression, with response rates and times superior to other available antidepressant therapies. Neuroimaging research has been pivotal in improving the field's mechanistic understanding of ECT, with a growing number of magnetic resonance imaging studies demonstrating hippocampal plasticity after ECT, in line with evidence of upregulated neurotrophic processes in the hippocampus in animal models. However, the precise roles of the hippocampus and other brain regions in antidepressant response to ECT remain unclear. Seizure physiology may also play a role in antidepressant response to ECT, as indicated by early positron emission tomography, single-photon emission computed tomography, and electroencephalography research and corroborated by recent magnetic resonance imaging studies. In this review, we discuss the evidence supporting neuroplasticity in the hippocampus and other brain regions during and after ECT, and their associations with antidepressant response. We also offer a mechanistic, circuit-level model that proposes that core mechanisms of antidepressant response to ECT involve thalamocortical and cerebellar networks that are active during seizure generalization and termination over repeated ECT sessions, and their interactions with corticolimbic circuits that are dysfunctional prior to treatment and targeted with the electrical stimulus.

Early Electroconvulsive Therapy in Patients With Major Depressive Disorder: A Propensity Score-Matched Analysis Using a Nationwide Inpatient Database in Japan

OBJECTIVES

This study aimed to evaluate whether early electroconvulsive therapy (ECT) can reduce length of hospital stay and total hospitalization costs in major depressive disorder (MDD) patients.

METHODS

Using the Japanese Diagnosis Procedure Combination inpatient database from April 2011 to March 2018 linked with the Annual Report for Functions of Medical Institutions, we identified patients admitted for MDD. Patients who received ECT within 8 days of admission were assigned to the early ECT group and the remaining patients to the control group. The primary outcomes were length of hospital stay and total hospitalization costs. The secondary outcomes were in-hospital mortality and fatal adverse events. Propensity score-matched analyses were performed to compare the outcomes between the 2 groups.

RESULTS

We identified 41,248 eligible patients, comprising 1169 in the early ECT group and 40,079 in the control group. After 1:1 propensity score matching, patients in the early ECT group had significantly shorter length of hospital stay than those in the control group (difference: -12.6 days; 95% confidence interval: -17.4 to -7.7 days). There was no significant difference in total hospitalization costs between the 2 groups. Early ECT was not significantly associated with increased in-hospital mortality or fatal adverse events.

CONCLUSIONS

Early ECT may reduce length of hospital stay without increasing total hospitalization costs or fatal adverse events in patients with MDD.

Impaired consciousness in epilepsy

Consciousness is essential to normal human life. In epileptic seizures consciousness is often transiently lost, which makes it impossible for the individual to experience or respond. These effects have huge consequences for safety, productivity, emotional health, and quality of life. To prevent impaired consciousness in epilepsy, it is necessary to understand the mechanisms that lead to brain dysfunction during seizures. Normally the consciousness system-a specialised set of cortical-subcortical structures-maintains alertness, attention, and awareness. Advances in neuroimaging, electrophysiology, and prospective behavioural testing have shed light on how epileptic seizures disrupt the consciousness system. Diverse seizure types, including absence, generalised tonic-clonic, and complex partial seizures, converge on the same set of anatomical structures through different mechanisms to disrupt consciousness. Understanding of these mechanisms could lead to improved treatment strategies to prevent impairment of consciousness and improve the quality of life of people with epilepsy.

Epilepsy and the consciousness system: transient vegetative state?

Recent advances have shown much in common between epilepsy and other disorders of consciousness. Behavior in epileptic seizures often resembles a transient vegetative or minimally conscious state. These disorders all converge on the "consciousness system" -the bilateral medial and lateral fronto-parietal association cortex and subcortical arousal systems. Epileptic unconsciousness has enormous clinical significance leading to accidental injuries, decreased work and school productivity, and social stigmatization. Ongoing research to better understand the mechanisms of impaired consciousness in epilepsy, including neuroimaging studies and fundamental animal models, will hopefully soon enable treatment trails to reduce epileptic unconsciousness and improve patient quality of life.

Imaging onset and propagation of ECT-induced seizures

PURPOSE

Regions of seizure onset and propagation in human generalized tonic-clonic seizures are not well understood. Cerebral blood flow (CBF) measurements with single photon emission computed tomography (SPECT) during electroconvulsive therapy (ECT)-induced seizures provide a unique opportunity to investigate seizure onset and propagation under controlled conditions.

METHODS

ECT stimulation induces a typical generalized tonic-clonic seizure, resembling spontaneous generalized seizures in both clinical and electroencephalogram (EEG) manifestations. Patients were divided into two groups based on timing of ictal (during seizure) SPECT tracer injections: 0 s after ECT stimulation (early group), and 30 s after ECT (late group). Statistical parametric mapping (SPM) was used to determine regions of significant CBF changes between ictal and interictal scans on a voxel-by-voxel basis.

RESULTS

In the early injection group, we saw increases near the regions of the bitemporal stimulating electrodes as well as some thalamic and basal ganglia activation. With late injections, we observed increases mainly in the parietal and occipital lobes, regions that were quiescent 30 s prior. Significant decreases occurred only at the later injection time, and these were localized to the bilateral cingulate gyrus and left dorsolateral frontal cortex.

CONCLUSIONS

Activations in distinct regions at the two time points, as well as sparing of intermediary brain structures, suggest that ECT-induced seizures propagate from the site of initiation to other specific brain regions. Further work will be needed to determine if this propagation occurs through cortical-cortical or cortico-thalamo-cortical networks. A better understanding of seizure propagation mechanisms may lead to improved treatments aimed at preventing seizure generalization.

Changes in regional cerebral blood flow during acute electroconvulsive therapy in patients with depression: positron emission tomographic study

BACKGROUND

Although electroconvulsive therapy (ECT) is widely used to treat psychiatric disorders such as depression, its precise neural mechanisms remain unknown.

AIMS

To investigate the time course of changes in cerebral blood flow during acute ECT.

METHOD

Cerebral blood flow was quantified serially prior to, during and after acute ECT in six patients with depression under anaesthesia using [(15)O]H(2)O positron emission tomography (PET).

RESULTS

Cerebral blood flow during ECT increased particularly in the basal ganglia, brain-stem, diencephalon, amygdala, vermis and the frontal, temporal and parietal cortices compared with that before ECT. The flow increased in the thalamus and decreased in the anterior cingulate and medial frontal cortex soon after ECT compared with that before ECT.

CONCLUSIONS

These results suggest a relationship between the centrencephalic system and seizure generalisation. Further, they suggest that some neural mechanisms of action of ECT are mediated via brain regions including the anterior cingulate and medial frontal cortex and thalamus.

Focal network involvement in generalized seizures: new insights from electroconvulsive therapy

Generalized seizures are commonly thought to involve the entire brain homogeneously. However, recent evidence suggests that selective cortical-subcortical networks may be crucial for the initiation, propagation, and behavioral manifestations of generalized seizures, while other brain regions are relatively spared. Here we review previous studies, and describe a new human model system for the investigation of generalized seizures: single-photon emission computed tomography, ictal-interictal difference imaging of generalized tonic-clonic seizures induced by electroconvulsive therapy (ECT). Bitemporal ECT activates focal bilateral frontotemporal and parietal association cortex, sparing other regions; bifrontal ECT activates mainly prefrontal cortex; while in right unilateral ECT the left frontotemporal region is relatively spared. Associated midline subcortical networks are also involved. Focal verbal memory deficits parallel the focal regions involved in these neuroimaging studies. Further studies of this kind may elucidate specific networks in generalized tonic-clonic seizures, providing targets for new therapeutic interventions in epilepsy.

Targeted prefrontal cortical activation with bifrontal ECT

The anatomical brain regions involved in the therapeutic and adverse actions of electroconvulsive therapy (ECT) are unknown. Previous studies suggest that bifrontal vs. bitemporal ECT differ in therapeutic efficacy and cognitive side effects. We therefore performed cerebral blood flow (CBF) imaging during bitemporal vs. bifrontal ECT-induced seizures to identify regions crucial for the differences between these treatments. Patients with major depression, undergoing bitemporal or bifrontal ECT, were studied. Ictal-interictal SPECT images were analyzed with statistical parametric mapping for bitemporal (n=11 image pairs in 8 patients) and bifrontal (n=4 image pairs in 2 patients) ECT-induced seizures to identify regions of ictal CBF changes. Bifrontal ECT was found to cause increases in CBF in prefrontal and anterior cingulate regions. Bitemporal ECT, however, caused CBF increases in the lateral frontal cortex and in the anterior temporal lobes. In bifrontal ECT, a greater increase in prefrontal activation, while sparing the temporal lobes, may result in a better therapeutic response and fewer adverse effects on memory than bitemporal ECT.

Effects of electroconvulsive therapy on regional cerebral blood flow measured by 99mtechnetium HMPAO SPECT

Decreased cerebral blood flow is documented in depression. In this study, 15 patients were studied with 99mTc-HMPAO SPECT before and after a course of electroconvulsive therapy (ECT). Improvement in frontal and temporal hypoperfusion was seen only in those patients who responded to ECT. Cerebral hypoperfusion may be a state-dependent marker in depressive illness.

Dynamic variations of local cerebral blood flow in maximal electroshock seizures in the rat

PURPOSE

Measurement of cerebral blood flow is routinely used to locate the areas involved in generation and spread of seizures in epilepsy patients. Because the nature of the hyperperfused regions varies with the timing of injection of tracer, in this study, we used a rat model of maximal electroshock seizures to follow up the time-dependent changes in the distribution of seizure-induced cerebral blood flow (CBF) changes.

METHODS

CBF was measured by the quantitative autoradiographic [14C]iodoantipyrine technique over a 30-s duration. The tracer was injected either at 15 s before seizure induction, simultaneous with the application of the electroshock (tonic phase), at the onset of the clonic phase, or at 3 and 6 min after the seizure (postictal phase).

RESULTS

Rates of CBF underwent dynamic changes during the different phases of seizure activity and largely increased over control levels (< or =400%) in the 45 regions studied during all phases of the seizure (first 3 times). CBF remained higher than control levels in 35 and 15 areas at 3 and 6 min after the seizure, respectively.

CONCLUSIONS

The distribution of maximal CBF increases showed a good correlation with their known involvement in the circuits underlying the clinical expression of the different types of seizure activity, tonic versus clonic.

[Check-ups with brain SPECT in electroconvulsive therapy in patients with severe drug-resistant depressive episodes and Parkinson's disease]

We have studied three women (66,72 and 72 years) with Parkinson's disease of 11, 6 and 21 years of evolution and drug-resistant severe depressive episodes treated with electroconvulsive therapy (ECT). We have performed a brain SPECT (99mTc-HMPAO) before and after the ECT. The clinical improvement of the severe depressive episodes were measured using the Hamilton score. The first patient did not experience any clinical improvement (Hamilton score 42 to 42). In this patient the brain SPECT before treatment presented a reduced perfusion in the posterior parietal region, anterior cingulate cortex and medial frontal and parietal cortex. After the treatment, the brain SPECT did not present significant variations. The second patient presented a moderate clinical improvement (Hamilton score 46 to 36) and also presented moderate improvement in the neurological symptoms. The brain SPECT before the treatment showed reduced perfusion in the left temporal cortex and medium-posterior parietal cortex. After the treatment, it also did not reflect significant variations. The third patient experienced a very good response to the ECT sessions (Hamilton score 45 to 10) and also an improvement regarding the neurological symptoms. This patient presented a reduced perfusion in the medium-posterior parietal regions in the brain SPECT performed before the treatment; these regions presented a moderate improvement in the brain SPECT performed after the treatment. The patient who presented a significant neurological and psychiatric improvement also presented an improvement in the perfusion of the decreased areas in the brain SPECT and showed fewer alterations in the baseline brain SPECT compared with the others. The brain SPECT could have a prognostic (and confirmation) role regarding clinical improvement induced by ECT in resistant depression in Parkinson's disease. ECT is an alternative in treatment of severe depressive drug-resistant episodes associated to the Parkinson's disease.

Subtypes of memory dysfunction associated with ECT: characteristics and neurobiological bases

Electroconvulsive therapy (ECT) is an effective treatment for a variety of psychiatric syndromes. However, one of its adverse secondary effects is neurocognitive dysfunction. The aim of this paper is to review different subtypes of memory dysfunction associated with ECT from a neuropsychological perspective. Declarative memory is clearly impaired after ECT. Immediate memory, however, is broadly preserved. Few studies have addressed procedural and incidental memory. Selective memory is impaired, probably due to the disruption of specific brain regions. Some of the possible neurobiological bases of ECT memory dysfunction are discussed in this paper. Synaptic plasticity, the cerebral neurotransmission system, and cerebral metabolism are examined in relation to the dysfunction and subsequent recovery of each memory subtype.

Structural and functional neuroimaging of electroconvulsive therapy and transcranial magnetic stimulation

Neuroimaging has long been utilized to provide a measure of the effects of electroconvulsive therapy (ECT) on brain structure and function as well as to better understand its mechanisms of action. In a similar fashion, functional neuroimaging may provide the means to elucidate both the underlying neurobiological effects and therapeutic potential of transcranial magnetic stimulation (TMS). This article will review findings of neuroimaging studies of both TMS and ECT, concentrating on how such studies may help guide treatment.

Transient frontal hypoperfusion in Tc-99m hexamethylpropyleneamineoxime single photon emission computed tomography imaging during alcohol withdrawal

BACKGROUND

Regional brain perfusion in patients during alcohol-withdrawal has been relatively less studied with brain SPECT technique. In this study, the hypothesis that possible regional cerebral blood flow (rCBF) alterations due to alcohol withdrawal might be transitory in a homogenous group of alcoholic patients in terms of their physical-nutritional and cognitive functional conditions was investigated.

METHODS

Fifteen right-handed male inpatients with alcohol-withdrawal, diagnosed according to DSM-IIIR criteria, and 6 male physically-mentally healthy control subjects were included in the study. The first Technetium 99m-hexamethylpropyleneamineoxime (Tc-99m-HMPAO) brain SPECT investigation was performed on the day of admission in nonmedicated conditions and the second one was performed after all the withdrawal symptoms had subsided in the patients. As an indicator of the change in the brain perfusion, a relative perfusion index was used and the relative tracer activity was expressed as the ratio of mean cortical region of interest activity to mean the whole cortical brain activity.

RESULTS

We found significantly reduced left frontal and right frontal, parietal and temporal rCBF values in the patients during the alcohol-withdrawal compared to those of their remitted state while they were not different from in the control group (p < 0.05).

CONCLUSIONS

Our data indicate that the alterations in rCBF during the alcohol-withdrawal are more pronounced both in the frontal cortex and in overall right hemisphere regions. Furthermore, the frontal hypoperfusion may be transitory with recovery from alcohol-withdrawal whereas temporal hypoperfusion may continue after recovery probably depending on the previously administered high-dose benzodiazepines.

Short-term effects of electroconvulsive treatment on the uptake of 99mTc-exametazime into brain in major depression shown with single photon emission tomography

Fifteen patients with major depression who were being treated with bilateral electroconvulsive treatment (ECT) were investigated before and 45 min after a single ECT using split-dose Single Photon Emission Tomography (SPET or SPECT) with 99mTc-Exametazime. All patients suffered from unipolar depressive illness and were rated on the Newcastle scale and with the 17-item Hamilton scale. They completed tests of orientation and verbal memory on the day of ECT. For comparison, verbal memory was also tested on the preceding day. The uptake of 99mTc-Exametazime was expressed relative to calcarine/occipital cortex. Significant decreases in tracer uptake were confined to the inferior anterior cingulate cortex. The changes were correlated with the severity of depressive symptoms and more weakly with decrements of memory function produced by ECT; there was no significant correlation with stimulus intensity or electroencephalographic measures of seizure duration.

Disparity in regional cerebral blood flow during electrically induced seizure

This is a presentation of 2 cases in which the intraictal regional cerebral blood flow distribution was measured with the 99mTc-HMPAO single photon emission computerized tomography technique during an electrically induced seizure. Although the seizure was verified as generalized on electroencephalography, the regional neuronal activity expressed as rCBF unexpectedly was markedly asymmetrical in one of the cases. These findings demonstrated that the 99mTc-HMPAO technique makes it possible to discriminate intraictal variation in cortical and subcortical activation between the hemispheres during electroencephalography-verified generalized seizures.

SPECT imaging in psychiatry. A review

In the last two decades, brain imaging has become an integral part of clinical and research psychiatry. Single photon computed emission tomography (SPECT) is rapidly gaining acceptance as one of the major imaging techniques available, along with computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET). Each of these techniques has its assets and drawbacks. This review concerns SPECT, a highly prevalent imaging technique whose potential value in brain imaging has not been appreciated until recently. Its purpose is to expose practicing clinicians and research psychiatrists alike to the attributes of this instrument, which is available in most nuclear medicine departments today. An effort is made to provide a comprehensive account of this technique, including a brief summary of the basic principles, the various methods of its application, and recent findings in most psychiatric disorders. Analogies to its "aristocratic cousin," PET, are presented to emphasize similarities and differences. Finally, directions for future development and implementation of SPECT are suggested.