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Chaitanya G, Malik R, Kadipasaoglu CM, Thompson SA, Tandon N, Pati S, Lhatoo SD. Anatomo-electro-clinical substrates of stereoelectroencephalography recorded fixation-off sensitivity. Clin Neurophysiol 2024; 163:223-225. [PMID: 38795631 DOI: 10.1016/j.clinph.2024.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/01/2024] [Accepted: 05/04/2024] [Indexed: 05/28/2024]
Affiliation(s)
- Ganne Chaitanya
- Texas Institute of Restorative Neurotechnologies (TIRN), Department of Neurology, The University of Texas Health Science Center at Houston (UTHealth), Houston, ON, Canada.
| | - Ramsha Malik
- Department of Neurology, Willis Knighton Health, Shreveport, LA, USA
| | | | | | - Nitin Tandon
- Department of Neurosurgery, The University of Texas Health Science Center at Houston (UTHealth), Houston, TX, USA
| | - Sandipan Pati
- Texas Institute of Restorative Neurotechnologies (TIRN), Department of Neurology, The University of Texas Health Science Center at Houston (UTHealth), Houston, ON, Canada
| | - Samden D Lhatoo
- Texas Institute of Restorative Neurotechnologies (TIRN), Department of Neurology, The University of Texas Health Science Center at Houston (UTHealth), Houston, ON, Canada
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Jordán Z, Szabó JP, Sákovics A, Kelemen A, Halász L, Erőss L, Fabó D. Epileptiform discharges in the anterior thalamus of epilepsy patients. iScience 2024; 27:109582. [PMID: 38726366 PMCID: PMC11079473 DOI: 10.1016/j.isci.2024.109582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 07/25/2023] [Accepted: 03/25/2024] [Indexed: 05/12/2024] Open
Abstract
Anterior thalamus (ANT) deep-brain stimulation (DBS) is an approved therapy for drug resistant epilepsy. We aimed to identify interictal epileptiform discharges (IED) in the ANT and to investigate their relationship with surface IEDs. Fifteen patients were monitored for two consecutive nights with externalized thalamic leads to analyze the intrathalamic epileptiform activities (TIED). Forty-six % of all contacts were located within the ANT. We found that all the responders had TIEDs within the ANT, while this held true only for 44% of the non-responders. The overall response rate (RR) at 1-year follow-up was 40%, while it was 44% in bilateral ANT hit patients and 45% in epileptic focus side hit. However, in case of TIEDs present in the focus side the RR reached as high as 71%. TIED activity may prove the pathophysiological connection to the seizure focus, and stimulation of this area might have a better suppressing effect on seizures.
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Affiliation(s)
- Zsófia Jordán
- Epilepsy Unit, Department of Neurosurgery and Neurointervention, Faculty of Medicine, Semmelweis University, 1145 Budapest, Hungary
- Member of the ERN EpiCARE, Budapest, Hungary
| | - Johanna-Petra Szabó
- Epilepsy Unit, Department of Neurosurgery and Neurointervention, Faculty of Medicine, Semmelweis University, 1145 Budapest, Hungary
- Member of the ERN EpiCARE, Budapest, Hungary
- János Szentágothai Neuroscience Program, School of PhD Studies, Semmelweis University, 1085 Budapest, Hungary
- Lendület Laboratory of Systems Neuroscience, Institute of Experimental Medicine, 1083 Budapest, Hungary
| | - Anna Sákovics
- Epilepsy Unit, Department of Neurosurgery and Neurointervention, Faculty of Medicine, Semmelweis University, 1145 Budapest, Hungary
- Member of the ERN EpiCARE, Budapest, Hungary
- János Szentágothai Neuroscience Program, School of PhD Studies, Semmelweis University, 1085 Budapest, Hungary
| | - Anna Kelemen
- Epilepsy Unit, Department of Neurosurgery and Neurointervention, Faculty of Medicine, Semmelweis University, 1145 Budapest, Hungary
- Member of the ERN EpiCARE, Budapest, Hungary
- András Pető Faculty, Semmelweis University, 1125 Budapest, Hungary
| | - László Halász
- Functional Neurosurgery Unit, Department of Neurosurgery and Neurointervention, Faculty of Medicine, Semmelweis University, 1145 Budapest, Hungary
| | - Loránd Erőss
- Functional Neurosurgery Unit, Department of Neurosurgery and Neurointervention, Faculty of Medicine, Semmelweis University, 1145 Budapest, Hungary
| | - Dániel Fabó
- Epilepsy Unit, Department of Neurosurgery and Neurointervention, Faculty of Medicine, Semmelweis University, 1145 Budapest, Hungary
- Member of the ERN EpiCARE, Budapest, Hungary
- Department of Neurology, University of Szeged, 6720 Szeged, Hungary
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Manjunatha RT, Vakilna YS, Chaitanya G, Alamoudi O, Ilyas A, Pati S. Advancing the frontiers of thalamic neuromodulation: A review of emerging targets and paradigms. Epilepsy Res 2023; 196:107219. [PMID: 37660585 DOI: 10.1016/j.eplepsyres.2023.107219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 08/23/2023] [Accepted: 08/27/2023] [Indexed: 09/05/2023]
Abstract
The thalamus is a key structure that plays a crucial role in initiating and propagating seizures. Recent advancements in neuroimaging and neurophysiology have identified the thalamus as a promising target for neuromodulation in drug-resistant epilepsies. This review article presents the latest innovations in thalamic targets and neuromodulation paradigms being explored in pilot or pivotal clinical trials. Multifocal temporal plus or posterior quadrant epilepsies are evaluated with pulvinar thalamus neuromodulation, while centromedian thalamus is explored in generalized epilepsies and Lennox Gastaut syndrome. Multinodal thalamocortical neuromodulation with novel stimulation paradigms such as long bursting or low-frequency stimulation is being investigated to quench the epileptic network excitability. Beyond seizure control, thalamic neuromodulation to restore consciousness is being studied. This review highlights the promising potential of thalamic neuromodulation in epilepsy treatment, offering hope to patients who have not responded to conventional medical therapies. However, it also emphasizes the need for larger randomized controlled trials and personalized stimulation paradigms to improve patient outcomes further.
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Affiliation(s)
- Ramya Talanki Manjunatha
- Texas Institute of Restorative Neurotechnologies [TIRN], University of Texas Health Science Center, Houston, TX, USA; Texas Comprehensive Epilepsy Program, Texas Institute of Restorative Neurotechnologies, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Yash Shashank Vakilna
- Texas Institute of Restorative Neurotechnologies [TIRN], University of Texas Health Science Center, Houston, TX, USA; Texas Comprehensive Epilepsy Program, Texas Institute of Restorative Neurotechnologies, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Ganne Chaitanya
- Texas Institute of Restorative Neurotechnologies [TIRN], University of Texas Health Science Center, Houston, TX, USA; Texas Comprehensive Epilepsy Program, Texas Institute of Restorative Neurotechnologies, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Omar Alamoudi
- Texas Institute of Restorative Neurotechnologies [TIRN], University of Texas Health Science Center, Houston, TX, USA; Texas Comprehensive Epilepsy Program, Texas Institute of Restorative Neurotechnologies, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Adeel Ilyas
- Department of Neurosurgery, UAB Heersink School of Medicine, Birmingham, AL, USA
| | - Sandipan Pati
- Texas Institute of Restorative Neurotechnologies [TIRN], University of Texas Health Science Center, Houston, TX, USA; Texas Comprehensive Epilepsy Program, Texas Institute of Restorative Neurotechnologies, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA.
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Skelton HM, Brandman DM, Bullinger K, Isbaine F, Gross RE. Distinct Biomarkers of ANT Stimulation and Seizure Freedom in an Epilepsy Patient with Ambulatory Hippocampal Electrocorticography. Stereotact Funct Neurosurg 2023; 101:349-358. [PMID: 37742626 DOI: 10.1159/000533680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 08/15/2023] [Indexed: 09/26/2023]
Abstract
INTRODUCTION Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) and responsive neurostimulation (RNS) of the hippocampus are the predominant approaches to brain stimulation for treating mesial temporal lobe epilepsy (MTLE). Both are similarly effective at reducing seizures in drug-resistant patients, but the underlying mechanisms are poorly understood. In rare cases where it is clinically indicated to use RNS and DBS simultaneously, ambulatory electrophysiology from RNS may provide the opportunity to measure the effects of ANT DBS in the putative seizure onset zone and identify biomarkers associated with clinical improvement. Here, one such patient became seizure free, allowing us to identify and compare the changes in hippocampal electrophysiology associated with ANT stimulation and seizure freedom. METHODS Ambulatory electrocorticography and clinical history were retrospectively analyzed for a patient treated with RNS and DBS for MTLE. DBS artifacts were used to identify ANT stimulation periods on RNS recordings and measure peri-stimulus electrographic changes. Clinical history was used to determine the chronic electrographic changes associated with seizure freedom. RESULTS ANT stimulation acutely suppressed hippocampal gamma (25-90Hz) power, with minimal theta (4-8Hz) suppression and without clear effects on seizure frequency. Eventually, the patient became seizure free alongside the emergence of chronic gamma increase and theta suppression, which started at the same time as clobazam was introduced. Both seizure freedom and the associated electrophysiology persisted after inadvertent DBS discontinuation, further implicating the clobazam relationship. Unexpectedly, RNS detections and long episodes increased, although they were not considered to be electrographic seizures, and the patient remained clinically seizure free. CONCLUSION ANT stimulation and seizure freedom were associated with distinct, dissimilar spectral changes in RNS-derived electrophysiology. The time course of these changes supported a new medication as the most likely cause of clinical improvement. Broadly, this work showcases the use of RNS recordings to interpret the effects of multimodal therapy. Specifically, it lends additional credence to hippocampal theta suppression as a biomarker previously associated with seizure reduction in RNS patients.
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Affiliation(s)
- Henry M Skelton
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, Georgia, USA,
- Morehouse School of Medicine, Atlanta, Georgia, USA,
| | - David M Brandman
- Department of Neurosurgery, University of California, Davis, California, USA
| | - Katie Bullinger
- Department of Neurology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Faical Isbaine
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Robert E Gross
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, Georgia, USA
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Dong L, Zhao T, Duan JK, Tian L, Zheng Y. Effect of high-frequency stimulation on the complexity of low-Mg 2+-induced epileptiform discharge rhythm waves in the CA3 region of rat hippocampal slices. Biochem Biophys Res Commun 2023; 673:59-66. [PMID: 37356146 DOI: 10.1016/j.bbrc.2023.06.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 06/14/2023] [Indexed: 06/27/2023]
Abstract
High-frequency stimulation (HFS) is a crucial therapeutic approach for neurodegenerative conditions, such as epilepsy. However, its underlying mechanism of inhibition remains unclear. In this study, a rat model of epileptiform discharges (EDs) was constructed by perfusing brain slices with magnesium-free artificial cerebrospinal fluid (aCSF), where after HFS was used to stimulate the CA3 area of the hippocampus. The EDs signals of each sub-region of hippocampal slices before and after HFS were recorded based on a multi-electrode Array (MEA). Secondly, the changes of approximate entropy (ApEn) complexity of rhythms in different regions of hippocampal slices before and after HFS were deeply analyzed The results showed that different rhythm characteristics of EDs signals exhibited significant differences before and after HFS. Here HFS significantly inhibited the delta rhythm of field potential and enhanced the beta rhythm. Finally, the changing rhythm of the EDs signal in the propagation path before and after HFS was analyzed, and it was found that the inhibitory target of HFS on EDs signal was in the CA3b sub-region. The rhythm would gradually decline with the propagation of EDs signal in the hippocampal neural pathway. This study shows that HFS can modulate the local field potential, thus inhibiting the pathological rhythm caused by epilepsy, which provides a novel research incentive for HFS to inhibit EDs.
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Affiliation(s)
- Lei Dong
- School of Life Sciences, Tiangong University, Tianjin, 300387, China; State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin, 300072, China
| | - Tong Zhao
- School of Life Sciences, Tiangong University, Tianjin, 300387, China
| | - Jia-Kang Duan
- School of Life Sciences, Tiangong University, Tianjin, 300387, China
| | - Lei Tian
- School of Life Sciences, Tiangong University, Tianjin, 300387, China
| | - Yu Zheng
- School of Life Sciences, Tiangong University, Tianjin, 300387, China.
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Ono H, Sonoda M, Sakakura K, Kitazawa Y, Mitsuhashi T, Firestone E, Jeong JW, Luat AF, Marupudi NI, Sood S, Asano E. Dynamic cortical and tractography atlases of proactive and reactive alpha and high-gamma activities. Brain Commun 2023; 5:fcad111. [PMID: 37228850 PMCID: PMC10204271 DOI: 10.1093/braincomms/fcad111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 10/15/2022] [Accepted: 04/03/2023] [Indexed: 05/27/2023] Open
Abstract
Alpha waves-posterior dominant rhythms at 8-12 Hz reactive to eye opening and closure-are among the most fundamental EEG findings in clinical practice and research since Hans Berger first documented them in the early 20th century. Yet, the exact network dynamics of alpha waves in regard to eye movements remains unknown. High-gamma activity at 70-110 Hz is also reactive to eye movements and a summary measure of local cortical activation supporting sensorimotor or cognitive function. We aimed to build the first-ever brain atlases directly visualizing the network dynamics of eye movement-related alpha and high-gamma modulations, at cortical and white matter levels. We studied 28 patients (age: 5-20 years) who underwent intracranial EEG and electro-oculography recordings. We measured alpha and high-gamma modulations at 2167 electrode sites outside the seizure onset zone, interictal spike-generating areas and MRI-visible structural lesions. Dynamic tractography animated white matter streamlines modulated significantly and simultaneously beyond chance, on a millisecond scale. Before eye-closure onset, significant alpha augmentation occurred at the occipital and frontal cortices. After eye-closure onset, alpha-based functional connectivity was strengthened, while high gamma-based connectivity was weakened extensively in both intra-hemispheric and inter-hemispheric pathways involving the central visual areas. The inferior fronto-occipital fasciculus supported the strengthened alpha co-augmentation-based functional connectivity between occipital and frontal lobe regions, whereas the posterior corpus callosum supported the inter-hemispheric functional connectivity between the occipital lobes. After eye-opening offset, significant high-gamma augmentation and alpha attenuation occurred at occipital, fusiform and inferior parietal cortices. High gamma co-augmentation-based functional connectivity was strengthened, whereas alpha-based connectivity was weakened in the posterior inter-hemispheric and intra-hemispheric white matter pathways involving central and peripheral visual areas. Our results do not support the notion that eye closure-related alpha augmentation uniformly reflects feedforward or feedback rhythms propagating from lower to higher order visual cortex, or vice versa. Rather, proactive and reactive alpha waves involve extensive, distinct white matter networks that include the frontal lobe cortices, along with low- and high-order visual areas. High-gamma co-attenuation coupled to alpha co-augmentation in shared brain circuitry after eye closure supports the notion of an idling role for alpha waves during eye closure. These normative dynamic tractography atlases may improve understanding of the significance of EEG alpha waves in assessing the functional integrity of brain networks in clinical practice; they also may help elucidate the effects of eye movements on task-related brain network measures observed in cognitive neuroscience research.
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Affiliation(s)
- Hiroya Ono
- Department of Pediatrics, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
- Department of Pediatric Neurology, National Center of Neurology and Psychiatry, Joint Graduate School of Tohoku University, Tokyo 1878551, Japan
- Department of Pediatrics, UCLA Mattel Children’s Hospital, David Geffen School of Medicine, Los Angeles, CA 90095, USA
| | - Masaki Sonoda
- Department of Pediatrics, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
- Department of Neurosurgery, Graduate School of Medicine, Yokohama City University, Yokohama 2360004, Japan
| | - Kazuki Sakakura
- Department of Pediatrics, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
- Department of Neurosurgery, University of Tsukuba, Tsukuba 3058575, Japan
| | - Yu Kitazawa
- Department of Pediatrics, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
- Department of Neurology and Stroke Medicine, Yokohama City University, Yokohama, Kanagawa 2360004, Japan
| | - Takumi Mitsuhashi
- Department of Pediatrics, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
- Department of Neurosurgery, Juntendo University, School of Medicine, Tokyo 1138421, Japan
| | - Ethan Firestone
- Department of Physiology, Wayne State University, Detroit, MI 48201, USA
| | - Jeong-Won Jeong
- Department of Pediatrics, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
- Department of Neurology, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
| | - Aimee F Luat
- Department of Pediatrics, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
- Department of Neurology, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
- Department of Pediatrics, Central Michigan University, Mount Pleasant, MI 48858, USA
| | - Neena I Marupudi
- Department of Neurosurgery, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
| | - Sandeep Sood
- Department of Neurosurgery, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
| | - Eishi Asano
- Department of Pediatrics, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
- Department of Neurology, Children’s Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
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Fisher RS. Deep brain stimulation of thalamus for epilepsy. Neurobiol Dis 2023; 179:106045. [PMID: 36809846 DOI: 10.1016/j.nbd.2023.106045] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/22/2023] Open
Abstract
Neuromodulation (neurostimulation) is a relatively new and rapidly growing treatment for refractory epilepsy. Three varieties are approved in the US: vagus nerve stimulation (VNS), deep brain stimulation (DBS) and responsive neurostimulation (RNS). This article reviews thalamic DBS for epilepsy. Among many thalamic sub-nuclei, DBS for epilepsy has been targeted to the anterior nucleus (ANT), centromedian nucleus (CM), dorsomedial nucleus (DM) and pulvinar (PULV). Only ANT is FDA-approved, based upon a controlled clinical trial. Bilateral stimulation of ANT reduced seizures by 40.5% at three months in the controlled phase (p = .038) and 75% by 5 years in the uncontrolled phase. Side effects related to paresthesias, acute hemorrhage, infection, occasional increased seizures, and usually transient effects on mood and memory. Efficacy was best documented for focal onset seizures in temporal or frontal lobe. CM stimulation may be useful for generalized or multifocal seizures and PULV for posterior limbic seizures. Mechanisms of DBS for epilepsy are largely unknown, but animal work points to changes in receptors, channels, neurotransmitters, synapses, network connectivity and neurogenesis. Personalization of therapies, in terms of connectivity of the seizure onset zone to the thalamic sub- nucleus and individual characteristics of the seizures, might lead to improved efficacy. Many questions remain about DBS, including the best candidates for different types of neuromodulation, the best targets, the best stimulation parameters, how to minimize side effects and how to deliver current noninvasively. Despite the questions, neuromodulation provides useful new opportunities to treat people with refractory seizures not responding to medicines and not amenable to resective surgery.
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Affiliation(s)
- Robert S Fisher
- Department of Neurology and Neurological Sciences and Neurosurgery by Courtesy, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, 213 Quarry Road, Room 4865, Palo Alto, CA 94304, USA.
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Grogan DP, Skelton HM, Fernandez AM, Gutekunst CANE, Gross RE. The laterodorsal tegmentum and seizure regulation: Revisiting the evidence. J Neurosci Res 2023; 101:256-262. [PMID: 36349730 DOI: 10.1002/jnr.25144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 10/26/2022] [Indexed: 11/10/2022]
Abstract
Electrical deep brain stimulation (DBS) is now a routine treatment option for patients suffering from medically refractory epilepsy. DBS of the anterior nucleus of the thalamus (ANT) has proven to be effective but, despite its success, few patients experience complete cessation of seizure activity. However, improving the therapy is challenging because the mechanism underlying its action remains largely unknown. One angle on improving the effectiveness of ANT stimulation is to better understand the various anatomic regions that send projections to and through this area. Here, the authors utilized a connectomic atlas of the mouse brain to better understand the regions projecting to the ANT and were particularly interested by the presence of robust cholinergic projections from the laterodorsal tegmentum (LDT). A subsequent review of the literature resulted in limited studies, which presented convincing evidence supporting this region's role in seizure control present in acute rodent models of epilepsy. It is thus the purpose of this paper to encourage further research into the role of the LDT on seizure mitigation, with mechanistic effects likely stemming from its cholinergic projections to the ANT. While previous studies have laid a firm foundation supporting the role of this region in modulation of seizure activity, modern scientific methodology has yet to be applied to further elucidate the mechanisms and potential benefits associated with LDT stimulation in the epileptic population.
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Affiliation(s)
- Dayton P Grogan
- Department of Neurosurgery, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Henry M Skelton
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Alejandra M Fernandez
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Robert E Gross
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, Georgia, USA.,Department of Neurology, Emory University, Atlanta, Georgia, USA
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Gadot R, Korst G, Shofty B, Gavvala JR, Sheth SA. Thalamic stereoelectroencephalography in epilepsy surgery: a scoping literature review. J Neurosurg 2022; 137:1210-1225. [PMID: 35276641 DOI: 10.3171/2022.1.jns212613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 01/10/2022] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Stereoelectroencephalography (sEEG) is a well-established surgical method for defining the epileptogenic network. Traditionally reserved for identifying discrete cortical regions for resection or ablation, sEEG in current practice is also used for identifying more broadly involved subcortical epileptic network components, driven by the availability of brain-based neuromodulation strategies. In particular, sEEG investigations including thalamic nuclei are becoming more frequent in parallel with the increase in therapeutic strategies involving thalamic targets such as deep brain stimulation (DBS) and responsive neurostimulation (RNS). The objective to this study was to evaluate existing evidence and trends regarding the purpose, techniques, and relevant electrographic findings of thalamic sEEG. METHODS MEDLINE and Embase databases were systematically queried for eligible peer-reviewed studies involving sEEG electrode implantation into thalamic nuclei of patients with epilepsy. Available data were abstracted concerning preoperative workup and purpose for implanting the thalamus, thalamic targets and trajectories, and electrophysiological methodology and findings. RESULTS sEEG investigations have included thalamic targets for both basic and clinical research purposes. Medial pulvinar, dorsomedial, anterior, and centromedian nuclei have been the most frequently studied. Few studies have reported any complications with thalamic sEEG implantation, and no studies have reported long-term complications. Various methods have been utilized to characterize thalamic activity in epileptic disorders including evoked potentials, power spectrograms, synchronization indices, and the epileptogenicity index. Thalamic intracranial recordings are beginning to be used to guide neuromodulation strategies including RNS and DBS, as well as to understand complex, network-dependent seizure disorders. CONCLUSIONS Inclusion of thalamic coverage during sEEG evaluation in drug-resistant epilepsy is a growing practice and is amenable to various methods of electrographic data analysis. Further study is required to establish well-defined criteria for thalamic implantation during invasive investigations as well as safety and ethical considerations.
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Affiliation(s)
| | | | | | - Jay R Gavvala
- 2Neurology, Baylor College of Medicine, Houston, Texas
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Piper RJ, Richardson RM, Worrell G, Carmichael DW, Baldeweg T, Litt B, Denison T, Tisdall MM. Towards network-guided neuromodulation for epilepsy. Brain 2022; 145:3347-3362. [PMID: 35771657 PMCID: PMC9586548 DOI: 10.1093/brain/awac234] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 05/30/2022] [Accepted: 06/16/2022] [Indexed: 11/30/2022] Open
Abstract
Epilepsy is well-recognized as a disorder of brain networks. There is a growing body of research to identify critical nodes within dynamic epileptic networks with the aim to target therapies that halt the onset and propagation of seizures. In parallel, intracranial neuromodulation, including deep brain stimulation and responsive neurostimulation, are well-established and expanding as therapies to reduce seizures in adults with focal-onset epilepsy; and there is emerging evidence for their efficacy in children and generalized-onset seizure disorders. The convergence of these advancing fields is driving an era of 'network-guided neuromodulation' for epilepsy. In this review, we distil the current literature on network mechanisms underlying neurostimulation for epilepsy. We discuss the modulation of key 'propagation points' in the epileptogenic network, focusing primarily on thalamic nuclei targeted in current clinical practice. These include (i) the anterior nucleus of thalamus, now a clinically approved and targeted site for open loop stimulation, and increasingly targeted for responsive neurostimulation; and (ii) the centromedian nucleus of the thalamus, a target for both deep brain stimulation and responsive neurostimulation in generalized-onset epilepsies. We discuss briefly the networks associated with other emerging neuromodulation targets, such as the pulvinar of the thalamus, piriform cortex, septal area, subthalamic nucleus, cerebellum and others. We report synergistic findings garnered from multiple modalities of investigation that have revealed structural and functional networks associated with these propagation points - including scalp and invasive EEG, and diffusion and functional MRI. We also report on intracranial recordings from implanted devices which provide us data on the dynamic networks we are aiming to modulate. Finally, we review the continuing evolution of network-guided neuromodulation for epilepsy to accelerate progress towards two translational goals: (i) to use pre-surgical network analyses to determine patient candidacy for neurostimulation for epilepsy by providing network biomarkers that predict efficacy; and (ii) to deliver precise, personalized and effective antiepileptic stimulation to prevent and arrest seizure propagation through mapping and modulation of each patients' individual epileptogenic networks.
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Affiliation(s)
- Rory J Piper
- Department of Neurosurgery, Great Ormond Street Hospital, London, UK
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - R Mark Richardson
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, USA
| | | | | | - Torsten Baldeweg
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Brian Litt
- Department of Neurology and Bioengineering, University of Pennsylvania, Philadelphia, USA
| | | | - Martin M Tisdall
- Department of Neurosurgery, Great Ormond Street Hospital, London, UK
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
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Schuler AL, Ferrazzi G, Colenbier N, Arcara G, Piccione F, Ferreri F, Marinazzo D, Pellegrino G. Auditory driven gamma synchrony is associated with cortical thickness in widespread cortical areas. Neuroimage 2022; 255:119175. [PMID: 35390460 PMCID: PMC9168448 DOI: 10.1016/j.neuroimage.2022.119175] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 02/20/2022] [Accepted: 04/02/2022] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVE Gamma synchrony is a fundamental functional property of the cerebral cortex, impaired in multiple neuropsychiatric conditions (i.e. schizophrenia, Alzheimer's disease, stroke etc.). Auditory stimulation in the gamma range allows to drive gamma synchrony of the entire cortical mantle and to estimate the efficiency of the mechanisms sustaining it. As gamma synchrony depends strongly on the interplay between parvalbumin-positive interneurons and pyramidal neurons, we hypothesize an association between cortical thickness and gamma synchrony. To test this hypothesis, we employed a combined magnetoencephalography (MEG) - Magnetic Resonance Imaging (MRI) study. METHODS Cortical thickness was estimated from anatomical MRI scans. MEG measurements related to exposure of 40 Hz amplitude modulated tones were projected onto the cortical surface. Two measures of cortical synchrony were considered: (a) inter-trial phase consistency at 40 Hz, providing a vertex-wise estimation of gamma synchronization, and (b) phase-locking values between primary auditory cortices and whole cortical mantle, providing a measure of long-range cortical synchrony. A correlation between cortical thickness and synchronization measures was then calculated for 72 MRI-MEG scans. RESULTS Both inter-trial phase consistency and phase locking values showed a significant positive correlation with cortical thickness. For inter-trial phase consistency, clusters of strong associations were found in the temporal and frontal lobes, especially in the bilateral auditory and pre-motor cortices. Higher phase-locking values corresponded to higher cortical thickness in the frontal, temporal, occipital and parietal lobes. DISCUSSION AND CONCLUSIONS In healthy subjects, a thicker cortex corresponds to higher gamma synchrony and connectivity in the primary auditory cortex and beyond, likely reflecting underlying cell density involved in gamma circuitries. This result hints towards an involvement of gamma synchrony together with underlying brain structure in brain areas for higher order cognitive functions. This study contributes to the understanding of inherent cortical functional and structural brain properties, which might in turn constitute the basis for the definition of useful biomarkers in patients showing aberrant gamma synchronization.
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Affiliation(s)
| | - Giulio Ferrazzi
- IRCCS San Camillo Hospital, Via Alberoni 70, Venice 30126, Italy
| | - Nigel Colenbier
- IRCCS San Camillo Hospital, Via Alberoni 70, Venice 30126, Italy
| | - Giorgio Arcara
- IRCCS San Camillo Hospital, Via Alberoni 70, Venice 30126, Italy
| | | | - Florinda Ferreri
- Unit of Neurology, Unit of Clinical Neurophysiology, Study Center of Neurodegeneration (CESNE), Department of Neuroscience, University of Padua, Padua, Italy; Department of Clinical Neurophysiology, Kuopio University Hospital, University of Eastern Finland, Kuopio, Finland
| | - Daniele Marinazzo
- Department of Data Analysis, Faculty of Psychology and Educational Sciences, Ghent University
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Fasano A, Eliashiv D, Herman ST, Lundstrom BN, Polnerow D, Henderson JM, Fisher RS. Experience and consensus on stimulation of the anterior nucleus of thalamus for epilepsy. Epilepsia 2021; 62:2883-2898. [PMID: 34697794 DOI: 10.1111/epi.17094] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/31/2021] [Accepted: 09/27/2021] [Indexed: 12/11/2022]
Abstract
Deep brain stimulation of the anterior nuclei of thalamus (ANT-DBS) is effective for reduction of seizures, but little evidence is available to guide practitioners in the practical use of this therapy. In an attempt to fill this gap, a questionnaire with 37 questions was circulated to 578 clinicians who were either engaged in clinical trials of or known users of DBS for epilepsy, with responses from 141, of whom 58.2% were epileptologists and 28.4% neurosurgeons. Multiple regions of the world were represented. The survey found that the best candidates for DBS were considered those with temporal or frontal seizures, refractory to at least two medicines. Motivations for renewing therapy upon battery depletion were reduced convulsive, impaired awareness, and severe seizures and improved quality of life. Targeting of leads mainly was by magnetic resonance imaging, sometimes with intraoperative imaging or microelectrode recording. The majority used transventricular approaches. Stimulation parameters mostly imitated the SANTE study parameters, except for initial stimulation amplitudes in the 2-3-V or -mA range, versus 5 V in the SANTE study. Stimulation intensity was most often increased or reduced, respectively, for lack of efficacy or side effects, but changes in active contacts, cycle time, and pulse duration were also employed. Mood or memory problems or paresthesias were the side effects most responsible for adjustments. Off-label sites stimulated included centromedian thalamus, hippocampus, neocortex, and a few others. Several physicians used DBS in conjunction with vagus nerve stimulation or responsive neurostimulation, although our study did not track efficacy for combined use. Experienced users varied more from published parameters than did inexperienced users. In conclusion, surveys of experts can provide Class IV evidence for the most prevalent practical use of ANT-DBS. We present a flowchart for one protocol combining common practices. Controlled comparisons will be needed to choose the best approach.
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Affiliation(s)
- Alfonso Fasano
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.,Division of Neurology, University of Toronto, Toronto, Ontario, Canada.,Krembil Brain Institute, Toronto, Ontario, Canada.,Center for Advancing Neurotechnological Innovation to Application, Toronto, Ontario, Canada
| | - Dawn Eliashiv
- Department of Neurology, UCLA Seizure Disorders Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Susan T Herman
- Epilepsy Program, Department of Neurology at Barrow Neurological Institute, Phoenix, Arizona, USA
| | | | | | - Jaimie M Henderson
- Department of Neurosurgery and, by courtesy, Neurology and Neurological Sciences, Wu Tsai Neurosciences Institute and Bio-X Institute, Stanford University, Stanford, California, USA
| | - Robert S Fisher
- Department of Neurology & Neurological Sciences and, by courtesy, Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA
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Burdette D, Mirro EA, Lawrence M, Patra SE. Brain-responsive corticothalamic stimulation in the pulvinar nucleus for the treatment of regional neocortical epilepsy: A case series. Epilepsia Open 2021; 6:611-617. [PMID: 34268893 PMCID: PMC8408587 DOI: 10.1002/epi4.12524] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 07/08/2021] [Accepted: 07/10/2021] [Indexed: 12/16/2022] Open
Abstract
Drug‐resistant focal epilepsy with regional neocortical seizure onsets originating from the posterior quadrant can be particularly difficult to treat with resective surgery due to the overlap with eloquent cortex. Published reports indicate that corticothalamic treatment targeting the anterior or centromedian nucleus of the thalamus with direct brain‐responsive stimulation may be an effective approach to treat regional neocortical epilepsy. The pulvinar has remained largely unstudied as a neurostimulation target to treat refractory epilepsy. Because the pulvinar has connections with the posterior quadrant, neurostimulation may be effective if applied to seizures originating in this area. We performed a retrospective chart review of patients with regional neocortical seizure onsets in the posterior quadrant treated with the RNS System. Demographics, epilepsy history, clinical seizure frequencies, and neuropsychological testing results were obtained from the chart. Electrocorticogram (ECoG) records stored by the RNS System were reviewed to evaluate electrographic seizure onset patterns. Our patients were followed for 10, 12.5, and 15 months. All patients were responders (≥50% seizure reduction), and two of the three patients experienced a ≥90% reduction in seizures at the last follow‐up. Pre‐ and postsurgical neuropsychological evaluations were compared for two of the patients, and there was no evidence of cognitive decline found in either patient. Interestingly, mild cognitive improvements were reported. The third patient had only postimplant neuropsychological testing data available. Findings for this patient suggested executive dysfunction that was present prior to the RNS System which did not worsen with surgery. A visual inspection of ECoGs revealed near‐simultaneous seizure onsets in neocortical and pulvinar leads in two patients. Seizure onsets in the third patient were more variable. This is the first published report of brain‐responsive neurostimulation targeting the pulvinar to treat refractory regional onset epilepsy of posterior quadrant origin.
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Toth E, Kumar S, Ganne C, Riley KO, Balasubramanian K, Pati S. Machine learning approach to detect focal-onset seizures in the human anterior nucleus of the thalamus. J Neural Eng 2020; 17. [PMID: 33059336 DOI: 10.1088/1741-2552/abc1b7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 10/15/2020] [Indexed: 01/03/2023]
Abstract
OBJECTIVE There is an unmet need to develop seizure detection algorithms from brain regions outside the epileptogenic cortex. The study aimed to demonstrate the feasibility of classifying seizures and interictal states from local field potentials (LFPs) recorded from the human thalamus- a subcortical region remote to the epileptogenic cortex. We tested the hypothesis that spectral and entropy-based features extracted from LFPs recorded from the anterior nucleus of the thalamus (ANT) can distinguish its state of ictal recruitment from other interictal states (including awake, sleep). APPROACH Two supervised machine learning tools (random forest and the random kitchen sink) were used to evaluate the performance of spectral (discrete wavelet transform-DWT), and time-domain (multiscale entropy-MSE) features in classifying seizures from interictal states in patients undergoing stereo EEG evaluation for epilepsy surgery. Under the supervision of IRB, field potentials were recorded from the ANT in consenting adults with drug-resistant temporal lobe epilepsy. Seizures were confirmed in the ANT using line-length and visual inspection. Wilcoxon rank-sum (WRS) method was used to test the differences in spectral patterns between seizure and interictal (awake and sleep) states. MAIN RESULTS 79 seizures (10 patients) and 158 segments (approx. 4 hours) of interictal stereo EEG data were analyzed. The mean seizure detection latencies with line length in the ANT varied between seizure types (range 5-34 seconds). However, the DWT and MSE in the ANT showed significant changes for all seizure types within the first 20 seconds after seizure onset. The random forest (accuracy 93.9 % and false-positive 4.6%) and the random kitchen sink (accuracy 97.3% and false-positive 1.8%) classified seizures and interictal states. SIGNIFICANCE These results suggest that features extracted from the thalamic LFPs can be trained to detect seizures that can be used for monitoring seizure counts and for closed-loop seizure abortive interventions.
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Affiliation(s)
- Emilia Toth
- University of Alabama School of Medicine, Birmingham, Alabama, UNITED STATES
| | - Sachin Kumar
- Centre for Computational Engineering and Networking , Amrita Vishwa Vidyapeetham Amrita School of Engineering, Coimbatore, Tamil Nadu, INDIA
| | - Chaitanya Ganne
- Neurology, University of Alabama at Birmingham, 1720 7th Ave S, Suite 405F, SPARKS building, Birmingham, UNITED STATES
| | - Kristen O Riley
- Neurosurgery, University of Alabama School of Medicine, Birmingham, Alabama, UNITED STATES
| | - Karthi Balasubramanian
- Department of Electronics and Communication Engineering, Amrita Vishwa Vidyapeetham Amrita School of Engineering, Coimbatore, Tamil Nadu, INDIA
| | - Sandipan Pati
- University of Alabama School of Medicine, Birmingham, Alabama, 35294-3412, UNITED STATES
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