Altered cerebral blood flow in patients with anti-NMDAR encephalitis

Abnormal global and local connectivity in patients with anti-N-methyl-D-aspartate receptor encephalitis: A resting-state functional MRI study

OBJECTIVE

We decided to investigate the changes of global and local connectivity in anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis patients based on eigenvector centrality (EC) and regional homogeneity (ReHo). We sought new biomarkers to identify the patients based on multivariate pattern analysis (MVPA).

METHODS

Functional MRI (fMRI) was performed on all participants. EC, ReHo and MVPA were used to analyze the fMRI images. The correlation between the global or local connectivity and neuropsychology tests was detected.

RESULTS

The MoCA scores of the patients were lower than those of the healthy controls (HCs), while the HAMD24 and HAMA scores of the patients were higher than those of the HCs. Increased EC values in the right calcarine (CAL.R) and decreased EC values in the right putamen (PUT.R) distinguished these subjects with anti-NMDAR encephalitis from HCs. The higher ReHo values in the left postcentral gyrus (PoCG.L) were detected in the patients. The correlation analysis showed that the EC values in the PUT.R were negatively correlated with HAMD24 and HAMA scores, while the ReHo values in the PoCG.L were negatively correlated with MoCA scores. Better classification performance was reached in the EC-based classifier (AUC = 0.80), while weaker classification performance was achieved in the ReHo-based classifier (AUC = 0.74) or the classifier based on EC and ReHo (AUC = 0.74). The brain areas with large weights were located in the frontal lobe, parietal lobe, cerebellum and basal ganglia.

CONCLUSION

Our findings suggest that abnormal global and local connectivity may play an important part in the pathophysiological mechanism of neuropsychiatric symptoms in the anti-NMDAR encephalitis patients. The EC-based classifier may be better than the ReHo-based classifier in identifying anti-NMDAR encephalitis patients.

Functional connectivity changes of the hippocampal subregions in anti-N-methyl-D-aspartate receptor encephalitis

The hippocampus plays an important role in the pathophysiological mechanism of Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis. Nevertheless, the connection between the resting-state activity of the hippocampal subregions and neuropsychiatric disorders in patients remains unclear. This study aimed to explore the changes in functional connectivity (FC) in the hippocampal subregions of patients with anti-NMDAR encephalitis and its association with clinical symptoms and cognitive performance. Twenty-three patients with anti-NMDAR encephalitis and 23 healthy controls (HC) were recruited. All participants underwent resting-state functional magnetic resonance imaging (rs-fMRI) scans and completed clinical cognitive scales. Based on the Brainnetome Atlas, the rostral (anterior) and caudal (posterior) hippocampi of both the left and right hemispheres were selected as regions of interest (ROIs) for FC analysis. First, a one-sample t-test was used to observe the whole-brain connectivity distribution of hippocampal subregions within the patient and HC groups at a threshold of p < 0.05. The two-sample t-test was used to compare the differences in hippocampal ROIs connectivity between groups, followed by a partial correlation analysis between the FC values of brain regions with statistical differences and clinical variables. This study observed that the distribution of whole-brain functional connectivity in the rostral and caudal hippocampi aligned with the connectivity differences between the anterior and posterior hippocampi. Compared to the HC group, the patients showed significantly decreased FC between the bilateral rostral hippocampus and the left inferior orbitofrontal gyrus and between the right rostral hippocampus and the right cerebellum. However, a significant increase in FC was observed between the right rostral hippocampus and left superior temporal gyrus, the left caudal hippocampus and right superior frontal gyrus, and the right caudal hippocampus and left gyrus rectus. Partial correlation analysis showed that FC between the left inferior orbitofrontal gyrus and the right rostral hippocampus was significantly negatively correlated with the California Verbal Learning Test (CVLT) and Brief Visuospatial Memory Test (BVMT) scores. The FC between the right rostral hippocampus and the left superior temporal gyrus was negatively correlated with BVMT scores. FC abnormalities in the hippocampal subregions of patients with anti-NMDAR encephalitis were associated with cognitive impairment, emotional changes, and seizures. These results may help explain the pathophysiological mechanisms and clinical manifestations of anti-NMDAR encephalitis and NMDAR dysfunction-related diseases such as schizophrenia.

Contribution of cerebrospinal fluid antibody titers and sex to acute cerebral blood flow in patients with anti-NMDAR autoimmune encephalitis

Objective

The objective of this study was to elucidate the contribution of cerebrospinal fluid (CSF) antibody titers (AT) and sex to acute cerebral blood flow (CBF) in patients diagnosed with anti-N-methyl-d-aspartate receptor autoimmune encephalitis (NMDAR AE).

Methods

Forty-five patients diagnosed with NMDAR AE were recruited from December 2016 to January 2023. The acute CBF in patients with NMDAR AE at the early stage of the disease was analyzed using arterial spin labeling. The groups were compared based on CSF AT and sex. The connectivity of the CBF in the region of interest was also compared between groups.

Results

The patients with different CSF AT exhibited varied brain regions with CBF abnormalities compared to the healthy subjects (p = 0.001, cluster-level FWE corrected). High antibody titers (HAT) in CSF contributed to more brain regions with CBF alterations in female patients than in female patients with low antibody titers (LAT) in CSF (p = 0.001, cluster-level FWE corrected). Female patients with HAT in CSF displayed more decreased CBF in the left post cingulum gyrus, left precuneus, left calcarine, and left middle cingulum gyrus than the male patients with the same AT in CSF (p = 0.001, cluster-level FWE corrected). All patients with NMDAR AE showed increased CBF in the left putamen (Putamen_L) and left amygdala (Amygdala_L) and decreased CBF in the right precuneus (Precuneus_R), which suggests that these are diagnostic CBF markers for NMDAR AE.

Conclusion

CSF AT and sex contributed to CBF abnormalities in the patients diagnosed with NMDAR AE. Altered CBF might potentially serve as the diagnostic marker for NMDAR AE.

Regional cerebral blood flow in a patient with asystole episodes associated with anti-NMDA receptor encephalitis

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is a rare and severe autoimmune encephalitis that displays neuropsychiatric symptoms and autonomic instability, e.g., hypoventilation and cardiac arrhythmia. Severe arrhythmia including asystole associated with this encephalitis is rare. Several causes have been suggested. Nevertheless, no report of the literature has described examination by functional brain imaging of a patient with asystole during anti-NMDA receptor encephalitis. This case is that of a 34-year-old woman diagnosed as having anti-NMDA receptor encephalitis. She repeatedly showed 10-20 s asystole episodes necessitating a temporary transvenous pacemaker. After resection of the bilateral ovarian cystic tumor, her symptoms improved. Regional cerebral blood flow (rCBF) was evaluated using single-photon emission computed tomography. The rCBF was increased in the amygdala, hypothalamus, anterior cingulate, hippocampus, and anterior temporal lobes, but decreased in the dorsolateral frontal lobes, parietal lobes, and occipital lobes. Findings in this case suggest that altered rCBF in the patient with asystole episodes associated with anti-NMDA receptor encephalitis was observed in several brain lesions. The rCBF increases in the central autonomic networks, i.e., the amygdala, hypothalamus, and anterior cingulate, might be associated with dysregulation of sympathetic and parasympathetic nervous systems leading to asystole.

Arterial Spin Labeling Changes Parallel Asymmetric Perisylvian and Perirolandic Symptoms in 3 Pediatric Cases of Anti-NMDAR Encephalitis

BACKGROUND AND OBJECTIVES

Anti-NMDA receptor autoimmune encephalitis (NMDAR AE) is an autoantibody-mediated disorder characterized by seizures, neuropsychiatric symptoms, movement disorder, and focal neurologic deficits. Conventionally defined broadly as an inflammatory brain disease, the heterotopic localization is rarely discussed in children. Imaging findings are often nonspecific, and there are no early biomarkers of disease other than the presence of anti-NMDAR antibodies.

METHODS

We conducted a retrospective analysis of our pediatric NMDAR AE cases (as determined by either positive serum or CSF antibodies or both) at Texas Children's Hospital between 2020-2021 and extracted medical record data of those patients who had arterial spin labeling (ASL) as part of their imaging workup for encephalitis. The ASL findings were described in the context of their symptoms and disease courses.

RESULTS

We identified 3 children on our inpatient floor, intensive care unit (ICU), and emergency department (ED) settings who were diagnosed with NMDAR AE and had ASL performed as part of their focal neurologic symptom workup. All 3 patients presented with focal neurologic deficits, expressive aphasia, and focal seizures before the onset of other well-characterized NMDAR AE symptoms. Their initial MRI revealed no diffusion abnormalities but uncovered asymmetric and predominantly unilateral multifocal hyperperfusion of perisylvian/perirolandic regions on ASL that correlated with focal EEG abnormalities and their focal examination findings. All 3 patients were treated with first-line and second-line therapies, and their symptoms improved.

DISCUSSION

We found that ASL may be a suitable early imaging biomarker to highlight perfusion changes corresponding to the functional localization of NMDAR AE in pediatric patients. We briefly highlight the neuroanatomic parallels between working models of schizophrenia, chronic NMDAR antagonist administration (ketamine abuse), and NMDAR AE affecting primarily language centers. The regional specificity seen in NMDAR hypofunction may make ASL a reasonable early and specific biomarker of NMDAR AE disease activity. Future studies are necessary to evaluate regional changes in those patients who present with primarily psychiatric phenotypes rather than classical focal neurologic deficits.

Hypometabolism of the left middle/medial frontal lobe on FDG-PET in anti-NMDA receptor encephalitis: Comparison with MRI and EEG findings

OBJECTIVES

To investigate changes in brain-glucose metabolism in anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, and compare results with MRI and electroencephalography (EEG) findings at different disease stages.

METHODS

The clinical data of 18 patients (median age, 35 years; 11 men) were retrospectively collected. Patients were divided into groups based on the time of symptom onset to examination, (≤1 month, >1 but ≤3 months, >3 months). Two-sample t-test results were compared with age and sex-paired healthy controls using statistical parametric mapping and verified using a NeuroQ software normal database with a discriminating z-score of 2.

RESULTS

Abnormal patterns on FDG-PET differed over time (T = 3.21-8.74, Z = 2.68-4.23, p < 0.005). Regional analysis showed hypometabolic left middle or medial frontal cortex in 4/5, 5/7, and 5/6 patients, respectively. Time-subgroup analysis revealed hypermetabolic supertemporal cortex in 4/5, 5/7, and 2/6, patients, respectively. MRI and EEG abnormalities in any region and stage occurred in 10/18 and 10/16 patients, respectively. MRI and EEG time-subgroup analysis showed abnormalities in 5/9, 4/5, and 1/4, and 1/3, 6/7, and 3/6 patients, respectively. Abnormal temporal lobes were detected most frequently in MRI analyses and occurred in 3/10 patients.

CONCLUSIONS

Decreased left middle/medial frontal metabolism could be common to all stages. Metabolism in other regions, MRI, and EEG results were associated with the progression of anti-NMDAR encephalitis. The sensitivity rate of FDG-PET was superior to that of MRI and EEG.

Serial assessment of multimodality imaging in anti-leucine-rich glioma-inactivated 1 antibody encephalitis: A case report

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.

Diffusion kurtosis imaging and diffusion tensor imaging parameters applied to white matter and gray matter of patients with anti-N-methyl-D-aspartate receptor encephalitis

Objectives

To compare parameters of diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) to evaluate which can better describe the microstructural changes of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis patients and to characterize the non-Gaussian diffusion patterns of the whole brain and their correlation with neuropsychological impairments in these patients.

Materials and methods

DTI and DKI parameters were measured in 57 patients with anti-NMDAR encephalitis and 42 healthy controls. Voxel-based analysis was used to evaluate group differences between white matter and gray matter separately. The modified Rankin Scale (mRS) was used to evaluate the severity of the neurofunctional recovery of patients, the Montreal Cognitive Assessment (MoCA) was used to assess global cognitive performance, and the Hamilton Depression Scale (HAMD) and fatigue severity scale (FSS) were used to evaluate depressive and fatigue states.

Results

Patients with anti-NMDAR encephalitis showed significantly decreased radial kurtosis (RK) in the right extranucleus in white matter (P < 0.001) and notably decreased kurtosis fractional anisotropy (KFA) in the right precuneus, the right superior parietal gyrus (SPG), the left precuneus, left middle occipital gyrus, and left superior occipital gyrus in gray matter (P < 0.001). Gray matter regions with decreased KFA overlapped with those with decreased RK in the left middle temporal gyrus, superior temporal gyrus (STG), supramarginal gyrus (SMG), postcentral gyrus (POCG), inferior parietal but supramarginal gyrus, angular gyrus (IPL) and angular gyrus (ANG) (P < 0.001). The KFA and RK in the left ANG, IPL and POCG correlated positively with MoCA scores. KFA and RK in the left ANG, IPL, POCG and SMG correlated negatively with mRS scores. KFA in the left precuneus and right SPG as well as RK in the left STG correlated negatively with mRS scores. No significant correlation between KFA and RK in the abnormal brain regions and HAMD and FSS scores was found.

Conclusion

The microstructural changes in gray matter were much more extensive than those in white matter in patients with anti-NMDAR encephalitis. The brain damage reflected by DKI parameters, which have higher sensitivity than parameters of DTI, correlated with cognitive impairment and the severity of the neurofunctional recovery.

Sodium oligomannate combined with rivastigmine may improve cerebral blood flow and cognitive impairment following CAR-T cell therapy: A case report

Chimeric antigen receptor-T (CAR-T) cell therapy is a breakthrough for B-cell hematological malignancies but is commonly associated with cytokine release syndrome and neurotoxicity and is occasionally complicated by neurological symptoms, such as cognitive disturbances. Currently, no effective treatments for CAR-T therapy-related cognitive impairment are available. Here, we present a 22-year-old patient with cognitive impairment who was treated with CAR-T cells as a salvage therapy for Burkitt lymphoma. One month after CAR-T cell infusion, he experienced memory loss that mainly manifested as forgetting recent-onset events. Two months of rehabilitation and hyperbaric oxygen therapy failed to provide clinical improvement. Subsequently, the patient improved with oral oxiracetam for 5 months. However, after 10 months of withdrawal, he showed significantly worse memory decline. Then, he began to take sodium oligomannate (22 February 2021). Follow-up testing at 6 and 12 months revealed maintenance of memory gains with sodium oligomannate alone or in combination with rivastigmine. Our case shows that CAR-T therapy may compromise cognitive function and that sodium oligomannate may have partial efficacy in restoring cognitive performance and activities of daily living. This may provide insights for further applications of sodium oligomannate for neurological symptoms, especially cognitive deficits following CAR-T cell therapy.

Circular inference predicts nonuniform overactivation and dysconnectivity in brain-wide connectomes

Schizophrenia is a severe mental disorder whose neural basis remains difficult to ascertain. Among the available pathophysiological theories, recent work has pointed towards subtle perturbations in the excitation-inhibition (E/I) balance within different neural circuits. Computational approaches have suggested interesting mechanisms that can account for both E/I imbalances and psychotic symptoms. Based on hierarchical neural networks propagating information through a message-passing algorithm, it was hypothesized that changes in the E/I ratio could cause a "circular belief propagation" in which bottom-up and top-down information reverberate. This circular inference (CI) was proposed to account for the clinical features of schizophrenia. Under this assumption, this paper examined the impact of CI on network dynamics in light of brain imaging findings related to psychosis. Using brain-inspired graphical models, we show that CI causes overconfidence and overactivation most specifically at the level of connector hubs (e.g., nodes with many connections allowing integration across networks). By also measuring functional connectivity in these graphs, we provide evidence that CI is able to predict specific changes in modularity known to be associated with schizophrenia. Altogether, these findings suggest that the CI framework may facilitate behavioral and neural research on the multifaceted nature of psychosis.

Arterial spin labeling perfusion imaging in an infant with anti-N-methyl-D-aspartate receptor encephalitis: A case report

BACKGROUND

Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is an autoimmune encephalitis characterized by complex neuropsychiatric syndromes and the presence of cerebrospinal fluid (CSF) antibodies against NMDAR. The characteristics of anti-NMDAR encephalitis in children, particularly infants, are unclear due to difficulties in neurologic assessment such as psychiatric symptoms. Additionally, subtle or non-specific findings of conventional magnetic resonance imaging (MRI) make early diagnosis even more difficult. Herein, we present the first case of infant anti-NMDAR encephalitis in which perfusion imaging demonstrated marked abnormalities and the absence of conventional MRI findings.

CASE PRESENTATION

The patient was an 11-month-old boy who was admitted because of seizure and prolonged fever. He presented with involuntary movements of the mouth and tongue. Brain MRI showed no morphological abnormalities, but three-dimensional arterial spin labeling (ASL) perfusion imaging showed reduced blood flow in the left temporal and frontal regions and the right cerebellum. After that, a positive anti-NMDAR antibody test result was received. Despite treatment with IVIG and methylprednisolone, the involuntary movements and autonomic dysfunction gradually became more prominent. After rituximab administration, the clinical symptoms improved slightly, and follow-up MRI revealed diffuse brain atrophy and improvement in the balance of brain perfusion.

CONCLUSIONS

To the best of our knowledge, this is the first case report of infantile anti-NMDAR encephalitis in which cerebral blood flow was evaluated using three-dimensional ASL perfusion imaging. Indeed, our case, which showed abnormalities only in ASL perfusion imaging, suggests that CBF assessment could aid in the early diagnosis of anti-NMDAR encephalitis in infants.

Cerebral Metabolic Network in Patients With Anti-N-Methyl-D-Aspartate Receptor Encephalitis on 18F-FDG PET Imaging

Background

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is the most common autoimmune encephalitis (AE), and the prognosis may significantly be improved if identified earlier and immune-related treated more effectively. This study evaluated the brain metabolic network using fluorodeoxyglucose positron emission tomography (FDG PET).

Material and methods

FDG PET imaging of patients with NMDAR encephalitis was used to investigate the metabolic connectivity network, which was analyzed using the graph theory. The results in patients were compared to those in age- and sex-matched healthy controls.

Results

The hub nodes were mainly in the right frontal lobe in patients with NMDAR encephalitis. The global and local efficiencies in most brain regions were significantly reduced, and the shortest characteristic path length was significantly longer, especially in the temporal and occipital lobes. Significant network functions of topology properties were enhanced in the right frontal, caudate nucleus, and cingulate gyrus. In addition, the internal connection integration in the left cerebral hemisphere was poor, and the transmission efficiency of Internet information was low.

Conclusion

The present findings indicate that those characteristic and connections of metabolic network were changed in the brain by graph theory analysis quantitatively, which is helpful to better understand neuropathological and physiological mechanisms in patients with anti-NMDAR encephalitis.

Progressive cortical and sub-cortical alterations in patients with anti-N-methyl-D-aspartate receptor encephalitis

BACKGROUND

Advanced structural analyses are increasingly being highly valued to uncover pathophysiological understanding of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Therefore, we aimed to explore whether and how antibody-mediated NMDAR dysfunction affected cortical and sub-cortical brain morphology and their relationship with clinical symptoms.

METHODS

We performed surface-based morphometry analyses, hippocampal segmentation, and correlational analyses in 24 patients with anti-NMDAR encephalitis after acute disease stage and 30 normal controls (NC) in this case-control study.

RESULTS

Patients showed significantly decreased cortical alterations mainly in language network (LN) and default mode network (DMN), as well as decreased gray matter volume in left cornu ammonis 1 (CA1) body of hippocampus. Further correlation analyses showed that the decreased cortical thickness in the right superior frontier gyrus was associated with decreased cognitive scores, the decreased cortical volume in the right pars triangulari and decreased surface area in the right pars operculari were associated with decreased memory scores, whereas decreased gray matter volume in the left CA1 body was significantly correlated with longer time between first symptom and imaging in the patients.

CONCLUSION

These results suggested that cognitive impairments resulted from long-term sequelae of the encephalitis were mainly associated with cortical alterations in LN and DMN and sub-cortical atrophy of left CA1 body, which can be served as effective features to assess disease progression in clinical routine examination.