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Cucca A, Manara CV, Catalan M, Liccari M, Antonutti L, Lombardo TMI, Cenacchi V, Rangan S, Mingolo S, Crisafulli C, Dore F, Murgia M, Agostini T, Manganotti P. Using illusions to understand hallucinations: differences in perceptual performances on illusory figures may underscore specific visuoperceptual impairments in Parkinson's disease. Front Neurosci 2023; 17:1256224. [PMID: 38125403 PMCID: PMC10732246 DOI: 10.3389/fnins.2023.1256224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 11/06/2023] [Indexed: 12/23/2023] Open
Abstract
Visual hallucinations are prevalent, potentially disabling symptoms of Parkinson's Disease. Multiple impairments in bottom-up sensory processing and top-down perceptual modulation are implicated in the pathophysiology of these phenomena. In healthy individuals, visual illusions are elicited by illusory figures through parametric manipulations of geometrical configurations, contrast, color, or spatial relationships between stimuli. These illusory percepts provide insight on the physiologic processes subserving conscious and unconscious perception. In this exploratory, cross-sectional, controlled study, perceptual performance on illusory figures was assessed on 11 PD patients with hallucinations, 10 non-hallucinating PD patients, and 10 age-matched healthy individuals. In order to characterize potential neural substrates of perceptual performances, patients' brain metabolic patterns on FDG PET were also analyzed. Illusions relying on attentional modulation and global perception were attenuated in PD patients without hallucinations. This pattern was no longer recognizable in hallucinating patients. Conversely, illusory effects normally counteracted by figure to background segregation and overlapping figures recognition were enhanced in PD patients with hallucinations. FDG PET findings further suggest that perceptual differences between PD patients might be linked to abnormal top-down perceptual modulation.
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Affiliation(s)
- Alberto Cucca
- Department of Life Sciences, University of Trieste, Trieste, Italy
- Department of Neurology, New York University Grossman School of Medicine, New York, NY, United States
| | | | - Mauro Catalan
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Marco Liccari
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Lucia Antonutti
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | | | - Valentina Cenacchi
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Sophie Rangan
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Serena Mingolo
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Carmelo Crisafulli
- Nuclear Medicine, Imaging Diagnostic Department University Hospital and Health Services of Trieste, Trieste, Italy
| | - Franca Dore
- Nuclear Medicine, Imaging Diagnostic Department University Hospital and Health Services of Trieste, Trieste, Italy
| | - Mauro Murgia
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Tiziano Agostini
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Paolo Manganotti
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
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Ajčević M, Iscra K, Furlanis G, Michelutti M, Miladinović A, Buoite Stella A, Ukmar M, Cova MA, Accardo A, Manganotti P. Cerebral hypoperfusion in post-COVID-19 cognitively impaired subjects revealed by arterial spin labeling MRI. Sci Rep 2023; 13:5808. [PMID: 37037833 PMCID: PMC10086005 DOI: 10.1038/s41598-023-32275-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 03/24/2023] [Indexed: 04/12/2023] Open
Abstract
Cognitive impairment is one of the most prevalent symptoms of post Severe Acute Respiratory Syndrome COronaVirus 2 (SARS-CoV-2) state, which is known as Long COVID. Advanced neuroimaging techniques may contribute to a better understanding of the pathophysiological brain changes and the underlying mechanisms in post-COVID-19 subjects. We aimed at investigating regional cerebral perfusion alterations in post-COVID-19 subjects who reported a subjective cognitive impairment after a mild SARS-CoV-2 infection, using a non-invasive Arterial Spin Labeling (ASL) MRI technique and analysis. Using MRI-ASL image processing, we investigated the brain perfusion alterations in 24 patients (53.0 ± 14.5 years, 15F/9M) with persistent cognitive complaints in the post COVID-19 period. Voxelwise and region-of-interest analyses were performed to identify statistically significant differences in cerebral blood flow (CBF) maps between post-COVID-19 patients, and age and sex matched healthy controls (54.8 ± 9.1 years, 13F/9M). The results showed a significant hypoperfusion in a widespread cerebral network in the post-COVID-19 group, predominantly affecting the frontal cortex, as well as the parietal and temporal cortex, as identified by a non-parametric permutation testing (p < 0.05, FWE-corrected with TFCE). The hypoperfusion areas identified in the right hemisphere regions were more extensive. These findings support the hypothesis of a large network dysfunction in post-COVID subjects with cognitive complaints. The non-invasive nature of the ASL-MRI method may play an important role in the monitoring and prognosis of post-COVID-19 subjects.
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Affiliation(s)
- Miloš Ajčević
- Department of Engineering and Architecture, University of Trieste, Trieste, Italy
| | - Katerina Iscra
- Department of Engineering and Architecture, University of Trieste, Trieste, Italy
| | - Giovanni Furlanis
- Clinical Unit of Neurology, Department of Medicine, Surgery and Health Sciences, Trieste University Hospital-ASUGI, University of Trieste, Trieste, Italy
| | - Marco Michelutti
- Clinical Unit of Neurology, Department of Medicine, Surgery and Health Sciences, Trieste University Hospital-ASUGI, University of Trieste, Trieste, Italy
| | | | - Alex Buoite Stella
- Clinical Unit of Neurology, Department of Medicine, Surgery and Health Sciences, Trieste University Hospital-ASUGI, University of Trieste, Trieste, Italy
| | - Maja Ukmar
- Radiology Unit, Department of Medicine, Surgery and Health Sciences, Trieste University Hospital-ASUGI, University of Trieste, Trieste, Italy
| | - Maria Assunta Cova
- Radiology Unit, Department of Medicine, Surgery and Health Sciences, Trieste University Hospital-ASUGI, University of Trieste, Trieste, Italy
| | - Agostino Accardo
- Department of Engineering and Architecture, University of Trieste, Trieste, Italy
| | - Paolo Manganotti
- Clinical Unit of Neurology, Department of Medicine, Surgery and Health Sciences, Trieste University Hospital-ASUGI, University of Trieste, Trieste, Italy.
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Wang K, Zhao X, Yuan L, Chen Q, Wang Q, Ai L. Cortical metabolic characteristics of anti-leucine-rich glioma-inactivated 1 antibody encephalitis based on 18F-FDG PET. Front Neurol 2023; 14:1100760. [PMID: 37064193 PMCID: PMC10102654 DOI: 10.3389/fneur.2023.1100760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 03/09/2023] [Indexed: 04/03/2023] Open
Abstract
PurposeA general glucose metabolism pattern is observed in patients with anti-leucine-rich glioma-inactivated 1 (LGI1) antibody encephalitis; however, it is unclear whether further subregional metabolic differences exist. Therefore, the present study aimed to conduct an in-depth exploration of the features of glucose metabolism within specific brain areas using 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET).Materials and methodsThis retrospective study enrolled thirteen patients confirmed with LGI1 antibody encephalitis who were admitted to Beijing Tiantan Hospital from June 2021 to September 2022. All patients underwent 18F-FDG PET before initiating clinical treatment. Changes in glucose metabolism in specific brain areas were analyzed using Cortex ID software. The laterality of 18F-FDG uptake was assessed, and differences in specific brain areas were compared using paired t-tests.ResultsSignificant metabolic changes in at least one brain region in 11 out of 13 patients (84.6%) were revealed by semi-quantitative analysis (z-score > 2). A bilateral decrease in the 18F-FDG metabolic pattern was revealed in almost all brain regions of interest; in contrast, a hypermetabolic pattern was observed in the medial temporal region, with mean z-scores of 1.75 ± 3.27 and 2.36 ± 5.90 on the left and right sides, respectively (p = 0.497). In the prefrontal and temporal lobes, 18F-FDG metabolism was significantly lower in the lateral region than in the medial region on both sides. For the cingulate cortex, significant hypometabolism was also observed in the posterior part compared to the anterior counterpart on both the left (z-score: −1.20 ± 1.93 vs. −0.42 ± 1.18, respectively; p = 0.047) and right (z-score: −1.56 ± 1.96 vs. −0.33 ± 1.63, respectively; p = 0.001) sides. However, a significant difference in regional metabolism was observed only on the left side (p = 0.041).ConclusionAn asymmetric 18F-FDG metabolic pattern exists in patients with anti-LGI1 encephalitis. Meanwhile, varied regional metabolic differences were revealed bilaterally in specific cerebral areas, which could be associated with the clinical manifestations.
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Affiliation(s)
- Kai Wang
- Department of Nuclear Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Xiaobin Zhao
- Department of Nuclear Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Leilei Yuan
- Department of Nuclear Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Qian Chen
- Department of Nuclear Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Qun Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Lin Ai
- Department of Nuclear Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- *Correspondence: Lin Ai,
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Wada T, Mori H, Shindo K. Serial assessment of multimodality imaging in anti-leucine-rich glioma-inactivated 1 antibody encephalitis: A case report. eNeurologicalSci 2022; 29:100426. [PMID: 36161067 PMCID: PMC9494171 DOI: 10.1016/j.ensci.2022.100426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/29/2022] [Accepted: 09/10/2022] [Indexed: 11/29/2022] Open
Abstract
In autoimmune encephalitis, abnormalities of diffusion-weighted imaging (DWI), fluid-attenuated inversion recovery (FLAIR), arterial spin labeling (ASL) in magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT) and 18F-fluorodeoxyglucose-positron emission tomography (18F-FDG-PET) have been reported. However, there are few studies of long-term follow-up of imaging. We report a case of anti-leucine-rich glioma-inactivated 1 antibody encephalitis whose MRI (DWI, FLAIR and ASL), 99mTcHM-PAO SPECT (PAO-SPECT) and 18F-FDG-PET were evaluated through the clinical course. ASL, PAO-SPECT and 18F-FDG-PET consistently showed abnormalities in almost the same area. Serial assessment of these imaging modalities is useful in evaluating disease activity and efficacy of treatment. We followed up anti-LGI1 encephalitis by comparing multimodality imaging. ASL, PAO-SPECT and 18F-FDG-PET showed similar trends of abnormalities. Serial assessment of imaging was useful in evaluating disease activity.
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Affiliation(s)
- Takafumi Wada
- Department of Neurology, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki/Okayama, 710-8602, Japan
| | - Hitoshi Mori
- Department of Neurology, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki/Okayama, 710-8602, Japan
| | - Katsuro Shindo
- Department of Neurology, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki/Okayama, 710-8602, Japan
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Tamayo Carabaño D, Acevedo Bañez I, Lojo Ramírez J, García Morillo J, García Solís D, Jiménez-hoyuela García J. 18F-FDG PET para el diagnóstico y evaluación de respuesta al tratamiento de encefalitis límbica autoinmune. Rev Esp Med Nucl Imagen Mol 2022. [DOI: 10.1016/j.remn.2022.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Tamayo Carabaño D, Acevedo Bañez I, Lojo Ramírez J, García Morillo J, García Solís D, Jiménez-hoyuela García J. 18F-FDG PET for the diagnosis and assessment of treatment response of autoimmune limbic encephalitis. Rev Esp Med Nucl Imagen Mol 2022. [PMID: 36150663 DOI: 10.1016/j.remnie.2022.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 06/24/2022] [Accepted: 06/25/2022] [Indexed: 11/22/2022]
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Affiliation(s)
- R Li
- Department of Medical ImagingTianjin Huanhu HospitalTianjin, ChinaDepartment of RadiologyThe First Medical Center of PLA General HospitalBeijing, China
| | - L Ma
- Department of RadiologyThe First Medical Center of PLA General HospitalBeijing, China
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Yedavalli VS, Hamam O, Bahouth M, Urrutia VC, Ahmed A, Lu H, Jones C, Luna LP, Sair HI, Lanzman B. Arterial Spin Labeling Imaging Characteristics of Anti-leucine-rich Glioma-Inactivated 1 Encephalitis: A Qualitative and Quantitative Analysis. Front Neurol 2022; 13:850029. [PMID: 35979060 PMCID: PMC9377014 DOI: 10.3389/fneur.2022.850029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 06/16/2022] [Indexed: 11/13/2022] Open
Abstract
Background and Significance Autoimmune encephalitis (AE) is a rare group of diseases that can present with stroke-like symptoms. Anti-leucine-rich glioma inactivated 1 (LGI1) encephalitis is an AE subtype that is infrequently associated with neoplasms and highly responsive to prompt immunotherapy treatment. Therefore, accurate diagnosis of LGI1 AE is essential in timely patient management. Neuroimaging plays a critical role in evaluating stroke and stroke mimics such as AE. Arterial Spin Labeling (ASL) is an MRI perfusion modality that measures cerebral blood flow (CBF) and is increasingly used in everyday clinical practice for stroke and stroke mimic assessment as a non-contrast sequence. Our goal in this preliminary study is to demonstrate the added value of ASL in detecting LGI1 AE for prompt diagnosis and treatment. Methods In this retrospective single center study, we identified six patients with seropositive LGI1 AE who underwent baseline MRI with single delay 3D pseudocontinuous ASL (pCASL), including five males and one female between ages 28 and 76 years, with mean age of 55 years. Two neuroradiologists qualitatively interpreted the ASL images by visual inspection of CBF using a two-point scale (increased, decreased) when compared to both the ipsilateral and contralateral unaffected temporal and non-temporal cortex. The primary measures on baseline ASL evaluation were a) presence of ASL signal abnormality, b) if present, signal characterization based on the two-point scale, c) territorial vascular distribution, d) localization, and e) laterality. Quantitative assessment was also performed on postprocessed pCASL cerebral blood flow (CBF) maps. The obtained CBF values were then compared between the affected temporal cortex and each of the unaffected ipsilateral parietal, contralateral temporal, and contralateral parietal cortices. Results On consensus qualitative assessment, all six patients demonstrated ASL hyperperfusion and corresponding FLAIR hyperintensity in the hippocampus and/or amygdala in a non-territorial distribution (6/6, 100%). The ASL hyperperfusion was found in the right hippocampus or amygdala in 5/6 (83%) of cases. Four of the six patients underwent initial follow-up imaging where all four showed resolution of the initial ASL hyperperfusion. In the same study on structural imaging, all four patients were also diagnosed with mesial temporal sclerosis (MTS). Quantitative assessment was separately performed and demonstrated markedly increased CBF values in the affected temporal cortex (mean, 111.2 ml/min/100 g) compared to the unaffected ipsilateral parietal cortex (mean, 49 ml/min/100 g), contralateral temporal cortex (mean, 58.2 ml/min/100 g), and contralateral parietal cortex (mean, 52.2 ml/min/100 g). Discussion In this preliminary study of six patients, we demonstrate an ASL hyperperfusion pattern, with a possible predilection for the right mesial temporal lobe on both qualitative and quantitative assessments in patients with seropositive LGI1. Larger scale studies are necessary to further characterize the strength of these associations.
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Affiliation(s)
- Vivek Srikar Yedavalli
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, MD, United States
- *Correspondence: Vivek Srikar Yedavalli
| | - Omar Hamam
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Mona Bahouth
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Victor Cruz Urrutia
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Amara Ahmed
- Florida State University School of Medicine, Tallahassee, FL, United States
| | - Hanzhang Lu
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Craig Jones
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Licia Pacheco Luna
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Haris Iqbal Sair
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Bryan Lanzman
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, MD, United States
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Li R, Jin S, Wang Y, Li JF, Xiao HF, Wang YL, Ma L. Brain Perfusion Alterations on 3D Pseudocontinuous Arterial Spin-Labeling MR Imaging in Patients with Autoimmune Encephalitis: A Case Series and Literature Review. AJNR Am J Neuroradiol 2022; 43:701-706. [PMID: 35393361 PMCID: PMC9089268 DOI: 10.3174/ajnr.a7478] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 02/08/2022] [Indexed: 01/26/2023]
Abstract
Autoimmune encephalitis is a heterogeneous group of newly identified disorders that are being diagnosed with increasing frequency. Early recognition and treatment of autoimmune encephalitis are crucial for patients, but diagnosis remains challenging and time-consuming. In this retrospective case series, we describe the findings of conventional MR imaging and 3D pseudocontinuous arterial spin-labeling in patients with autoimmune encephalitis confirmed by antibody testing. All patients with autoimmune encephalitis showed increased CBF in the affected area, even when some of them presented with normal or slightly abnormal findings on conventional MR imaging. Additionally, serial 3D pseudocontinuous arterial spin-labeling showed perfusion reduction in 1 patient after therapy. For patients with highly suspected autoimmune encephalitis, 3D pseudocontinuous arterial spin-labeling may be added to the clinical work-up. Further studies and longitudinal data are needed to corroborate whether and to what extent 3D pseudocontinuous arterial spin-labeling improves the diagnostic work-up in patients with autoimmune encephalitis compared with conventional MR imaging.
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Affiliation(s)
- R. Li
- From the Department of Medical Imaging (R.L., S.J.), Tianjin Huanhu Hospital, Tianjin, China,Department of Radiology (R.L., Y.W., J.-F.L., H.-F.X., Y.-L.W., L.M.), The First Medical Center of PLA General Hospital, Beijing, China,Department of Medical Imaging (R.L., S.J.), Affiliated Huanhu Hospital of Nankai University, Tianjin, China
| | - S. Jin
- From the Department of Medical Imaging (R.L., S.J.), Tianjin Huanhu Hospital, Tianjin, China,Department of Medical Imaging (R.L., S.J.), Affiliated Huanhu Hospital of Nankai University, Tianjin, China
| | - Y. Wang
- Department of Radiology (R.L., Y.W., J.-F.L., H.-F.X., Y.-L.W., L.M.), The First Medical Center of PLA General Hospital, Beijing, China
| | - J.-F. Li
- Department of Radiology (R.L., Y.W., J.-F.L., H.-F.X., Y.-L.W., L.M.), The First Medical Center of PLA General Hospital, Beijing, China
| | - H.-F. Xiao
- Department of Radiology (R.L., Y.W., J.-F.L., H.-F.X., Y.-L.W., L.M.), The First Medical Center of PLA General Hospital, Beijing, China
| | - Y.-L. Wang
- Department of Radiology (R.L., Y.W., J.-F.L., H.-F.X., Y.-L.W., L.M.), The First Medical Center of PLA General Hospital, Beijing, China
| | - L. Ma
- Department of Radiology (R.L., Y.W., J.-F.L., H.-F.X., Y.-L.W., L.M.), The First Medical Center of PLA General Hospital, Beijing, China
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Nabizadeh F, Ramezannezhad E, Sardaripour A, Seyedi SA, Salehi N, Rezaeimanesh N, Naser Moghadasi A. [18F]FDG brain PET and clinical symptoms in different autoantibodies of autoimmune encephalitis: a systematic review. Neurol Sci 2022. [PMID: 35486333 DOI: 10.1007/s10072-022-06094-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Accepted: 04/21/2022] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Autoimmune encephalitis (AE) is caused by the antibodies that target receptors and intracellular or surface proteins. To achieve the appropriate therapeutic results, early and proper diagnosis is still the most important issue. In this review, we provide an overview of FDG-PET imaging findings in AE patients and possible relation to different subtypes and clinical features. METHODS PubMed, Web of Science, and Scopus were searched in August 2021 using a predefined search strategy. RESULTS After two-step reviewing, 22 studies with a total of 332 participants were entered into our qualitative synthesis. In anti-NMDAR encephalitis, decreased activity in the occipital lobe was present, in addition, to an increase in frontal, parietal, and specifically medial temporal activity. Anti-VGKC patients showed altered metabolism in cortical and subcortical regions such as striata and cerebellum. Abnormal metabolism in patients with anti-LGI1 has been reported in diverse areas of the brain including medial temporal, hippocampus, cerebellum, and basal ganglia all of which had hypermetabolism. Hypometabolism in parietal, frontal, occipital lobes, temporal, frontal, and hippocampus was observed in AE patients with anti-GAD antibodies. CONCLUSION Our results indicate huge diversity in metabolic patterns among different AE subtypes and it is hard to draw a firm conclusion. Moreover, the timing of imaging, seizures, and acute treatments can alter the PET patterns strongly. Further prospective investigations with specific inclusion and exclusion criteria should be carried out to identify the metabolic defect in different AE subtypes.
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