Exploring Variances of White Matter Integrity and the Glymphatic System in Simple Febrile Seizures and Epilepsy

Abnormal structure and function of white matter in obsessive-compulsive disorder

BACKGROUND

Abnormal structure and function of gray matter (GM) have been discovered in the cortico-striatal-thalamic-cortical (CSTC) circuit in obsessive-compulsive disorder (OCD). The GM structure and function may be influenced by the structure and function of the white matter (WM). Therefore, it is crucial to explore the characteristics of WM in OCD.

METHODS

Diffusion tensor imaging and resting-state functional magnetic resonance imaging data of 52 patients with OCD and 39 healthy controls (HCs) were collected. The tract-based spatial statistics, amplitude of low-frequency fluctuations (ALFF), and structural-functional coupling approaches were utilized to explore the WM structure and function. Furthermore, the relationship between the abnormal WM structure and function and clinical symptoms of OCD was investigated using Pearson's correlation. Support vector machine was performed to evaluate whether patients with OCD could be identified with the changed WM structure and function.

RESULTS

Compared to HCs, the lower fractional anisotropy (FA) values of four clusters including the superior corona radiata, anterior corona radiata, right superior longitudinal fasciculus, corpus callosum, left posterior corona radiata, fornix, and the right anterior limb of internal capsule, reduced ALFF/FA ratio in the left anterior thalamic radiation (ATR), and the decreased functional connectivity between the left ATR and the left dorsal lateral prefrontal cortex within CSTC circuit at rest were observed in OCD. The decreased ALFF/FA ratio in the left ATR negatively correlated with Yale-Brown Obsessive-Compulsive Scale obsessive thinking scores and Hamilton Anxiety Rating Scale scores in OCD. Furthermore, the features that combined the abnormal WM structure and function performed best in distinguishing OCD from HCs with the appropriate accuracy (0.80), sensitivity (0.82), as well as specificity (0.80).

CONCLUSION

Current research discovered changed WM structure and function in OCD. Furthermore, abnormal WM structural-functional coupling may lead to aberrant GM connectivity within the CSTC circuit at rest in OCD.

TRIAL REGISTRATION

Study on the mechanism of brain network in obsessive-compulsive disorder with multi-model magnetic resonance imaging (ChiCTR-COC-17013301).

Glymphatic Imaging in Pediatrics

The glymphatic system, which facilitates cerebrospinal fluid (CSF) flow through the brain parenchyma, is important for brain development and waste clearance. Advances in imaging techniques, particularly magnetic resonance imaging, have make it possible to evaluate glymphatic structures and functions in vivo. Recently, several studies have focused on the development and alterations of the glymphatic system in pediatric disorders. This review discusses the development of the glymphatic system, advances of imaging techniques and their applications in pediatric disorders. First, the results of the reviewed studies indicate that the development of the glymphatic system is a long-lasting process that continues into adulthood. Second, there is a need for improved glymphatic imaging techniques that are non-invasive and fast to improve suitability for pediatric applications, as some of existing methods use contrast injection and are susceptible to motion artifacts from long scanning times. Several novel techniques are potentially feasible for pediatric patients and may be used in the future. Third, the glymphatic dysfunction is associated with a large number of pediatric disorders, although only a few have recently been investigated. In conclusion, research on the pediatric glymphatic system remains an emerging field. The preliminary applications of glymphatic imaging techniques have provided unique insight into the pathological mechanism of pediatric diseases, but mainly limited in visualization of enlarged perivascular spaces and morphological measurements on CSF volumes. More in-depth studies on glymphatic functions are required to improve our understanding of the mechanisms underlying brain development and pediatric diseases. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3.

Assessment of the glymphatic function in children with attention-deficit/hyperactivity disorder

OBJECTIVES

Whether the alternation of the glymphatic system exists in neurodevelopmental disease still remains unclear. In this study, we investigated structural and functional changes in the glymphatic system in the treatment-naïve attention-deficit/hyperactivity disorder (ADHD) children by quantitatively measuring the Virchow-Robin spaces (VRS) volume and diffusion tensor image-analysis along the perivascular space (DTI-ALPS).

METHODS

Forty-seven pediatric ADHD patients and 52 age- and gender-matched typically developing (TD) children were recruited in this prospective study. The VRS volume was calculated using a semi-automated approach in axial T2-weighted images. Diffusivities along the x-, y-, and z-axes in the projection, association, and subcortical neural fiber areas were measured. The ALPS index, a ratio that accentuated water diffusion along the perivascular space, was calculated. The Mann-Whitney U test was used to compare the quantitative parameters; Pearson's correlation was used to analyze the correlation with clinical symptoms.

RESULTS

The cerebral VRS volume (mean, 15.514 mL vs. 11.702 mL) and the VRS volume ratio in the ADHD group were larger than those in the TD group (all p < 0.001). The diffusivity along the x-axis in association fiber area and ALPS index were significantly smaller in the ADHD group vs. TD group (mean, 1.40 vs.1.59, p < 0.05 after false discovery rate adjustment). Besides, the ALPS index was related to inattention symptoms of ADHD (r =  - 0.323, p < 0.05).

CONCLUSIONS

Our study suggests that the glymphatic system alternation may participate in the pathogenesis of ADHD, which may be a new research direction for exploring the mechanisms of psycho-behavioral developmental disorders. Moreover, the VRS volume and ALPS index could be used as the metrics for diagnosing ADHD.

CLINICAL RELEVANCE STATEMENT

Considering the potential relevance of the glymphatic system for exploring the mechanisms of attention deficit/hyperactivity, the Virchow-Robin spaces volume and the analysis along the perivascular space index could be used as additional metrics for diagnosing the disorder.

KEY POINTS

• Increased Virchow-Robin space volume and decreased analysis along the perivascular space index were found in the treatment-naïve attention-deficit/hyperactivity disorder children. • The results of this study indicate that the glymphatic system alternation may have a valuable role in the pathogenesis of attention-deficit/hyperactivity disorder. • The analysis along the perivascular space index is correlated with inattention symptoms of attention-deficit/hyperactivity disorder children.

Increased thrombospondin-1 levels contribute to epileptic susceptibility in neonatal hyperthermia without seizures via altered synaptogenesis

Childhood febrile seizures (FS) represent one of the most common types of seizures and may lead to severe neurological damage and an increased risk of epilepsy. However, most children with fevers do not show clinical manifestations of convulsions, and the consequences of hyperthermia without seizures remain elusive. This study focused on hyperthermia not reaching the individual's seizure threshold (sub-FS stimulus). Changes in thrombospondin-1 (TSP-1) levels, synapses, seizure susceptibility, and seizure severity in subsequent FS were investigated in rats exposed to sub-FS stimuli. Pharmacological and genetic interventions were used to explore the role of TSP-1 in sub-FS-induced effects. We found that after sub-FS stimuli, the levels of TSP-1 and synapses, especially excitatory synapses, were concomitantly increased, with increased epilepsy and FS susceptibility. Moreover, more severe neuronal damage was found in subsequent FS. These changes were temperature dependent. Reducing TSP-1 levels by genetic intervention or inhibiting the activation of transforming growth factor-β1 (TGF-β1) by Leu-Ser-Lys-Leu (LSKL) led to lower synapse/excitatory synapse levels, decreased epileptic susceptibility, and attenuated neuronal injury after FS stimuli. Our study confirmed that even without seizures, hyperthermia may promote synaptogenesis, increase epileptic and FS susceptibility, and lead to more severe neuronal damage by subsequent FS. Inhibition of the TSP-1/TGF-β1 pathway may be a new therapeutic target to prevent detrimental sub-FS sequelae.

Role of the glymphatic system and perivascular spaces as a potential biomarker for post-stroke epilepsy

Stroke is one of the most common causes of acquired epilepsy, which can also result in disability and increased mortality rates particularly in elderly patients. No preventive treatment for post-stroke epilepsy is currently available. Development of such treatments has been greatly limited by the lack of biomarkers to reliably identify high-risk patients. The glymphatic system, including perivascular spaces (PVS), is the brain's waste clearance system, and enlargement or asymmetry of PVS (ePVS) is hypothesized to play a significant role in the pathogenesis of several neurological conditions. In this article, we discuss potential mechanisms for the role of perivascular spaces in the development of post-stroke epilepsy. Using advanced MR-imaging techniques, it has been shown that there is asymmetry and impairment of glymphatic function in the setting of ischemic stroke. Furthermore, studies have described a dysfunction of PVS in patients with different focal and generalized epilepsy syndromes. It is thought that inflammatory processes involving PVS and the blood-brain barrier, impairment of waste clearance, and sustained hypertension affecting the glymphatic system during a seizure may play a crucial role in epileptogenesis post-stroke. We hypothesize that impairment of the glymphatic system and asymmetry and dynamics of ePVS in the course of a stroke contribute to the development of PSE. Automated ePVS detection in stroke patients might thus assist in the identification of high-risk patients for post-stroke epilepsy trials. PLAIN LANGUAGE SUMMARY: Stroke often leads to epilepsy and is one of the main causes of epilepsy in elderly patients, with no preventative treatment available. The brain's waste removal system, called the glymphatic system which consists of perivascular spaces, may be involved. Enlargement or asymmetry of perivascular spaces could play a role in this and can be visualised with advanced brain imaging after a stroke. Detecting enlarged perivascular spaces in stroke patients could help identify those at risk for post-stroke epilepsy.

Structural connectivity as a predictive factor for responsiveness to levetiracetam treatment in epilepsy

PURPOSE

To investigate whether structural connectivity or glymphatic system function is a potential predictive factor for levetiracetam (LEV) response in patients with newly diagnosed epilepsy.

METHODS

We enrolled patients with newly diagnosed epilepsy who were administered LEV as initial monotherapy and underwent diffusion tensor imaging (DTI) at diagnosis. We categorized the patients into drug response. We used graph theory to calculate the network measures for structural connectivity based on the DTI scans in patients with epilepsy. Additionally, we evaluated glymphatic system function by calculating the DTI analysis along the perivascular space (DTI-ALPS) index based on DTI scans.

RESULTS

We enrolled 84 patients with epilepsy. The clinical factors and DTI-ALPS index did not differ between the groups. However, some of the structural connectivity measures significantly differ between the groups. The poor responders exhibited a higher mean clustering coefficient, global efficiency, and small-worldness index than the good responders (p = 0.003, p = 0.048, and p = 0.038, respectively). In the receiver operating characteristic curve analysis, the mean clustering coefficient exhibited the highest performance in predicting the responsiveness to LEV (area under the curve of 0.677). In the multiple logistic regression analysis, the mean clustering coefficient of the structural connectivity measures was the only significant predictor of LEV response (p = 0.014). Furthermore, in the survival analysis, the mean clustering coefficient was the only significant predictor of LEV response (p = 0.026).

CONCLUSION

We demonstrated that structural connectivity is a potential predictive factor for responsiveness to LEV treatment in patients with newly diagnosed epilepsy.

Anti-seizure medication response and the glymphatic system in patients with focal epilepsy

BACKGROUND AND PURPOSE

We aimed to evaluate (i) glymphatic system function in patients with focal epilepsy in comparison with healthy controls, and (ii) the association between anti-seizure medication (ASM) response and glymphatic system function by using diffusion tensor image analysis along the perivascular space (DTI-ALPS).

METHODS

We retrospectively enrolled 100 patients with focal epilepsy who had normal brain magnetic resonance imaging (MRI) findings, and classified them as "poor" or "good" ASM responders according to their seizure control at the time of brain MRI. We also included 79 age- and sex-matched healthy controls. All patients and healthy controls underwent conventional brain MRI and diffusion tensor imaging. The DTI-ALPS index was calculated using the DSI studio program.

RESULTS

Of the 100 patients with focal epilepsy, 38 and 62 were poor and good ASM responders, respectively. The DTI-ALPS index differed significantly between patients with focal epilepsy and healthy controls and was significantly lower in patients with focal epilepsy (1.55 vs. 1.70; p < 0.001). The DTI-ALPS index also differed significantly according to ASM response and was lower in poor ASM responders (1.48 vs. 1.59; p = 0.047). Furthermore, the DTI-ALPS index was negatively correlated with age (r = -0.234, p = 0.019) and duration of epilepsy (r = -0.240, p = 0.016) in patients with focal epilepsy.

CONCLUSION

Our study is the first to identify, in focal epilepsy patients, a greater reduction in glymphatic system function among poor ASM responders compared to good responders. To confirm our results, further prospective multicenter studies with large sample sizes are needed.

The cerebral lymphatic drainage system and its implications in epilepsy

The central nervous system has long been thought to lack a clearance system similar to the peripheral lymphatic system. Therefore, the clearance of metabolic waste in the central nervous system has been a subject of great interest in neuroscience. Recently, the cerebral lymphatic drainage system, including the parenchymal clearance system and the meningeal lymphatic network, has attracted considerable attention. It has been extensively studied in various neurological disorders. Solute accumulation and neuroinflammation after epilepsy impair the blood-brain barrier, affecting the exchange and clearance between cerebrospinal fluid and interstitial fluid. Restoring their normal function may improve the prognosis of epilepsy. However, few studies have focused on providing a comprehensive overview of the brain clearance system and its significance in epilepsy. Therefore, this review addressed the structural composition, functions, and methods used to assess the cerebral lymphatic system, as well as the neglected association with epilepsy, and provided a theoretical basis for therapeutic approaches in epilepsy.

The asymmetry of glymphatic system dysfunction in patients with temporal lobe epilepsy: A DTI-ALPS study

BACKGROUND AND PURPOSE

While the occurrence of glymphatic system dysfunction has been observed in temporal lobe epilepsy (TLE), the potential asymmetry of this system has yet to be investigated in the TLE context. We aimed to investigate the glymphatic system function in both hemispheres and to analyze asymmetric features of the glymphatic system in TLE patients using diffusion tensor image analysis along the perivascular space (DTI-ALPS) method.

MATERIALS AND METHODS

43 patients (left TLE (LTLE), n = 20; right TLE (RTLE), n = 23) and 39 healthy controls (HC) were enrolled in this study. The DTI-ALPS index was calculated for the left (left ALPS index) and right (right ALPS index) hemispheres respectively. An asymmetry index (AI) was calculated by AI = (Right - Left)/ [(Right + Left)/2] to represent the asymmetric pattern. Independent two sample t-test, two-sample paired t-test or one-way ANOVA with Bonferroni correction were conducted to compare the differences in ALPS indices and AI among the groups.

RESULTS

Both left ALPS index (p = 0.040) and right ALPS index (p = 0.001) of RTLE patients were significantly decreased, while only left ALPS index of LTLE patients (p = 0.005) was reduced. Compared to contralateral ALPS index, the ipsilateral ALPS index was significantly decreased in TLE (p = 0.008) and RTLE (p = 0.009) patients. Leftward asymmetry of the glymphatic system was found in HC (p = 0.045) and RTLE (p = 0.009) patients. The LTLE patients presented reduced asymmetric traits when compared to RTLE patients (p = 0.029).

CONCLUSION

The TLE patients exhibited altered ALPS indices, which could be triggered by glymphatic system dysfunction. Altered ALPS indices were more severe in ipsilateral than in the contralateral hemisphere. Moreover, LTLE and RTLE patients exhibited different change patterns of the glymphatic system. In addition, glymphatic system function presented asymmetric patterns in both normal adult brain and RTLE patients.

Cognitive Impairment in Chronic Kidney Disease Is Associated with Glymphatic System Dysfunction

Introduction

This study was designed to explore the associations between impaired cognition in chronic kidney disease (CKD) patients and the dysfunction of the glymphatic system.

Method

Data were obtained from 77 CKD patients and 50 age-matched healthy control individuals from the First Affiliated Hospital of Zhengzhou University. CKD patients were stratified into with and without impaired cognitive function. T2-weighted magnetic resonance imaging results were used to assess area ratios for the perivascular space and ventricles in participants, while the Montreal Cognitive Assessment and the Mini-Mental State Examination were employed to measure cognitive function. Correlations between the perivascular space or ventricle area ratios and cognitive impairment were assessed in CKD patients.

Results

Significant increases in the burden of enlarged perivascular spaces in the frontal cortex and basal ganglia were observed in CKD patients with cognitive impairment relative to those without such impairment, with a concomitant increase in analyzed ventricle area ratios. Enlarged perivascular spaces in the frontal cortex, basal ganglia and increased area ratios of lateral ventricles and 4th ventricle exhibited relatively high sensitivity and specificity as means of differing between the CKD patients with and without cognitive impairment.

Conclusion

These results indicate that the burden of enlarged perivascular spaces in the frontal cortex and basal ganglia and increases in ventricle area ratio values may offer utility as biomarkers that can aid in detection of even mild cognitive decline in individuals with CKD. The dysfunction of the glymphatic system may play a key role in the pathogenesis of CKD-related cognitive impairment.

Assessment of factors influencing glymphatic activity and implications for clinical medicine

The glymphatic system is a highly specialized fluid transport system in the central nervous system. It enables the exchange of the intercellular fluid of the brain, regulation of the movement of this fluid, clearance of unnecessary metabolic products, and, potentially, brain immunity. In this review, based on the latest scientific reports, we present the mechanism of action and function of the glymphatic system and look at the role of factors influencing its activity. Sleep habits, eating patterns, coexisting stress or hypertension, and physical activity can significantly affect glymphatic activity. Modifying them can help to change lives for the better. In the next section of the review, we discuss the connection between the glymphatic system and neurological disorders. Its association with many disease entities suggests that it plays a major role in the physiology of the whole brain, linking many pathophysiological pathways of individual diseases.

DTI-ALPS: An MR biomarker for motor dysfunction in patients with subacute ischemic stroke

Purpose

Brain glymphatic dysfunction is involved in the pathologic process of acute ischemic stroke (IS). The relationship between brain glymphatic activity and dysfunction in subacute IS has not been fully elucidated. Diffusion tensor image analysis along the perivascular space (DTI-ALPS) index was used in this study to explore whether glymphatic activity was related to motor dysfunction in subacute IS patients.

Methods

Twenty-six subacute IS patients with a single lesion in the left subcortical region and 32 healthy controls (HCs) were recruited in this study. The DTI-ALPS index and DTI metrics (fractional anisotropy, FA, and mean diffusivity, MD) were compared within and between groups. Spearman's and Pearson's partial correlation analyses were performed to analyze the relationships of the DTI-ALPS index with Fugl-Meyer assessment (FMA) scores and with corticospinal tract (CST) integrity in the IS group, respectively.

Results

Six IS patients and two HCs were excluded. The left DTI-ALPS index of the IS group was significantly lower than that of the HC group (t = −3.02, p = 0.004). In the IS group, a positive correlation between the left DTI-ALPS index and the simple Fugl-Meyer motor function score (ρ = 0.52, p = 0.019) and a significant negative correlation between the left DTI-ALPS index and the FA (R = −0.55, p = 0.023) and MD (R = −0.48, p = 0.032) values of the right CST were found.

Conclusions

Glymphatic dysfunction is involved in subacute IS. DTI-ALPS could be a potential magnetic resonance (MR) biomarker of motor dysfunction in subacute IS patients. These findings contribute to a better understanding of the pathophysiological mechanisms of IS and provide a new target for alternative treatments for IS.

Glymphatic system dysfunction in patients with occipital lobe epilepsy

BACKGROUND AND PURPOSE

We aimed to investigate the glymphatic system function in patients with occipital lobe epilepsy (OLE) and healthy controls using diffusion tensor image analysis along the perivascular space (DTI-ALPS) index.

METHODS

We retrospectively included 23 patients with OLE and 30 healthy controls. The participants underwent brain MRI, which was normal, and diffusion tensor imaging. We used the DSI Studio for data preprocessing, obtained the fiber orientation and diffusivities, and calculated the DTI-ALPS index from the diffusivity values associated with the projection and association fibers in the left hemisphere.

RESULTS

There were no differences in mean age (31.6 years [range: 13-58] vs. 31.3 years [range: 20-57], p = .912) and male sex ratio (10/23 [43.5%] vs. 15/30 [50.0%]) between the groups. Compared to healthy controls, the diffusivities in patients with OLE were higher along the Y-axis in the projection fiber and along the Z-axis in the association fiber and lower along the Y-axis in the association fiber. The DTI-ALPS index in patients with OLE was lower than that in the healthy controls (1.421 ± 0.171 vs. 1.667 ± 0.271, p < .001, 95% confidence interval of difference = 0.117-0.376, Test statistic t = 3.823). We found no association between the DTI-ALPS index and clinical characteristics in OLE.

CONCLUSION

The DTI-ALPS index in patients with OLE was significantly lower than that in healthy controls, suggesting glymphatic system dysfunction in OLE. The DTI-ALPS index could help assess the glymphatic system function in patients with epilepsy.

Variances of quantifying of Virchow-Robin spaces detecting the different functional status of glymphatic system in simple febrile seizures affected by seizures duration

The Virchow-Robin spaces (VRs) in the cerebral glymphatic system play a vital role in waste clearance from the brain. Simple febrile seizures (SFS) are a common type of seizures marked by an inappropriate fluid exchange. The mechanism of evident differences in glymphatic function among SFS with varying seizure duration is unknown. Therefore, the goal of this study was to see whether there were any variations in glymphatic function among SFS based on seizures duration. We retrospectively studied 30 children with SFS lasting more than 5 minutes (SFS > 5M), 40 children with SFS lasting 5 minutes or less (SFS ≤ 5M), and 35 healthy controls aged 6 to 60 months who underwent magnetic resonance imaging (MRI). A custom-designed automated method that used T2-weighted imaging (T2WI) to segment the visible VRs. The VRs metrics were measured and compared studied groups. The VRs metrics, seizure duration the time gap between seizure onset and MRI scan were studied as well. VRs counts were lower (P < .001) in the SFS ≤ 5M (445.80 ± 66.10) and the control (430.77 ± 182.55) groups in comparison to SFS > 5M (642.70 ± 100.62). Similar results were found for VRs volume (VRsvol_SFS > 5M, 8514.63 ± 835.33mm3, VRsvol_SFS ≤ 5M, 6390.43 ± 692.74 mm3, VRsvol_control, 6048.37 ± 111.50 mm3; P < .001). However, in the SFS ≤ 5M, VRs measurements were lower than in the SFS > 5M (P < .001). VRs measurements were positively connected with seizure duration and inversely correlated with the course following seizure onset and MRI scan time in both SFS groups. SFS are positively correlated to glymphatic dysfunction since they cause enlarged VRs; additionally, VRs can be used as a biomarker in SFS > 5M and contribute to the mechanism.

A tract-based spatial statistics study of white matter integrity in epilepsy

OBJECTIVE

To explore the changes of cerebral white matter diffusion tensor in epilepsy.

METHODS

This study was a retrospective study based on diffusion tensor imaging (DTI). Twenty-six epileptic patients and 42 normal controls matched for sex, age and handedness were enrolled in our research. Based on the method of tract-based spatial statistics (TBSS), we analyzed the changes of each relevant parameter index of DTI in white matter of the brain in all subjects, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD).

RESULTS

In comparison with the control group, epileptic patients had decreased FA and elevated MD, AD, and RD in the anterior thalamic radiation, corticospinal tract, forceps major, forceps minor, cingulum, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, superior longitudinal fasciculus and uncinate fasciculus (P < 0.05).

CONCLUSION

Widespread white matter integrity was observed in epileptic patients, which may be the structural basis for the development of affective disorders, impaired cognition, and motor abnormalities.

Children with autism spectrum disorder present glymphatic system dysfunction evidenced by diffusion tensor imaging along the perivascular space

This study used diffusion tensor imaging (DTI) along the perivascular space (DTI-ALPS) to assess glymphatic system function in autism spectrum disorder (ASD) compared to healthy controls. Patients with ASD may have glymphatic system dysfunction, which is related to age. We retrospectively included 30 children with ASD and 25 healthy controls in this study. 3T magnetic resonance imaging scanner was used to perform DTI magnetic resonance imaging on all participants, and the DTI-ALPS index was calculated from the DTI data. Additionally, we evaluated how the DTI-ALPS index differed between the 2 groups. Moreover, we examined the relationships between the bilateral DTI-ALPS index and the age of the participants. The DTI-ALPS index considerably differed between groups. In the left index (1.02 ± 0.12 vs. 1.27 ± 0.25, P < .001) and in the right index (1.03 ± 0.12 vs. 1.32 ± 0.20, P < .001), the DTI-ALPS in ASD patients was significantly lower than that in healthy controls. Furthermore, the DTI-ALPS index was strongly and positively associated with age. In patients with ASD, there is a glymphatic system dysfunction. This is intimately correlated to age. Our findings suggest the importance of the DTI-ALPS approach in assessing the function of the glymphatic system in ASD.

Glymphatic system impairment in patients with status epilepticus

OBJECTIVE

The aim of this study was to compare the function of the glymphatic system in patients with status epilepticus (SE) with that in healthy controls by diffusion tensor image analysis along the perivascular space (DTI-ALPS) method. We also investigated the association between glymphatic system function and the clinical characteristics of SE.

METHODS

We retrospectively enrolled 28 patients with SE and 31 healthy controls matched for age and sex. All study participants underwent diffusion tensor imaging using the same 3-T MRI scanner, and the DTI-ALPS index was calculated. We compared the DTI-ALPS index between the SE group and the control group. We also evaluated the associations of the DTI-ALPS index with etiology and type of SE, age, putative duration of seizure, time interval until MRI, seizure-related changes on diffusion-weighted imaging, and any previous structural lesions.

RESULTS

The DTI-ALPS index was significantly lower in the SE group than in the control group (1.462 ± 0.297 vs. 1.632 ± 0.270, p = 0.026) and was negatively correlated with age (r =  - 0.280, p = 0.032) in the SE group. However, there were no significant between-group differences in the DTI-ALPS index according to other clinical factors.

SIGNIFICANCE

The finding of a significantly lower DTI-ALPS index in the SE group suggests that the glymphatic system is impaired in patients with SE. DTI-ALPS is a useful tool for evaluation of the function of the glymphatic system in these patients.

Glymphatic system function in patients with newly diagnosed focal epilepsy

INTRODUCTION

The aim of this study was to analyze the glymphatic system function and its relationship with clinical characteristics, global diffusion tensor imaging (DTI) parameters, and global structural connectivity in treatment-naïve patients with newly diagnosed focal epilepsy.

METHODS

This retrospective single-center study investigated patients with focal epilepsy and healthy controls. All participants underwent routine brain magnetic resonance imaging and DTI. DTI analysis along the perivascular space (DTI-ALPS) was used to evaluate glymphatic system function. We also calculated the measures of global DTI parameters, including whole-brain fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), and performed a graph theoretical network analysis to measure global structural connectivity.

RESULTS

A total of 109 patients with focal epilepsy and 88 healthy controls were analyzed. There were no significant differences in the DTI-ALPS index (1.67 vs. 1.68, p = 0.861) between the groups. However, statistically significant associations were found between the DTI-ALPS index and age (r = -0.242, p = 0.01), FA (r = 0.257, p = 0.007), MD (r = -0.469, p < 0.001), AD (r = -0.303, p = 0.001), RD (r = -0.434, p < 0.001), and the assortative coefficient (r = 0.230, p = 0.016) in patients with focal epilepsy.

CONCLUSION

The main finding of this study is that DTI-ALPS index is significantly correlated with global DTI parameters and structural connectivity measures of the brain in patients with focal epilepsy. In addition, DTI-ALPS index decreases with age in these patients. We conclude that the DTI-ALPS index can be used to investigate glymphatic system function in patients with focal epilepsy.

Glymphatic system dysfunction in patients with juvenile myoclonic epilepsy

OBJECTIVE

The glymphatic system is a glial cell-dependent waste clearance pathway in the brain that is essential for the maintenance of brain homeostasis. In this study, we evaluated glymphatic system function in patients with juvenile myoclonic epilepsy (JME) compared with healthy controls.

METHODS

Patients with JME and healthy controls were retrospectively enrolled in this study. All the participants underwent brain diffusion tensor imaging (DTI). The "DTI-analysis along the perivascular space (ALPS)"-index was calculated to evaluate the glymphatic system function of the participants. The ALPS-indices of the patients with JME were compared with those of the healthy controls. In addition, the correlations between ALPS-index and the clinical characteristics of the patients with JME were analyzed to validate changes in glymphatic system function.

RESULTS

A total of 39 patients with JME and 38 healthy controls were enrolled in this study. The mean ALPS- index of the patients with JME was significantly lower than that of the healthy controls (1.541 vs. 1.653, p = 0.041). ALPS-index was negatively correlated with age in patients with JME (r = -0.375, p = 0.018). However, ALPS-index was not correlated with age at onset, duration of epilepsy, or anti-seizure medication load in patients with JME.

CONCLUSION

This study is the first in which the ALPS method was used to demonstrate that patients with JME have significant glymphatic system dysfunction. The results also show that glymphatic system index is negatively correlated with age in patients with JME, a finding which demonstrates that the glymphatic system function of patients with JME gradually declines with age. The ALPS-index might be a potential biomarker for monitoring glymphatic system function in patients with epilepsy.