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Alteration in asymmetry of glymphatic system function in patients with Self-limited epilepsy with centrotemporal spikes1Department of Radiology, the first affiliated hospital of Xi'an Jiaotong University, Xi‘an, China
Synopsis
Keywords: Epilepsy, Diffusion/other diffusion imaging techniques
Motivation: Self-limited epilepsy with centrotemporal spikes (SLECTS) is the most prevalent type of idiopathic childhood epilepsy. However, the underlying pathophysiologic mechanisms of SLECTS is largely unknown.
Goal(s): Studies on the glymphatic system function in SLECTS patients may contribute to better understanding of the associated mechanisms.
Approach: Diffusion tensor imaging analysis along the perivascular space (DTI-ALPS) was used to evaluate the glymphatic system function.
Results: The SLECTS patients exhibited altered DTI-ALPS index. Altered DTI-ALPS index were more severe in ipsilateral than in the contralateral hemisphere. Moreover, RSLECTS (Right SLECTS ) and LSLECTS (Left SLECTS) patients exhibited different change patterns of the glymphatic system.
Impact: This study indicating that the glymphatic system may be a separate system in the left and right hemispheres. Patients with RSLECTS and LSLECTS exhibited different pattern of glymphatic system changes. Our research may contribute to elucidating the pathophysiologic of SLECTS.
Methods：The local institutional review board approved this study and written informed consents were obtained from parents of the children. Subjects: Children diagnosed with SLECTS according diagnostic criteria defined by the International League Against Epilepsy[8].MRI protocols: All MR examinations were performed using a 3T scanner (Signa HDxt, GE Healthcare, Milwaukee, Wisconsin) with 8-channel head coil. The parameters of DTI sequence were as follows: TR/TE=11000ms/69.5ms, b values=0, 1000, thickness=2.5 mm, acquisition matrix =128×128, field of view=240×240mm2. Data analysis: The DTI-ALPS index were calculated for the right (right ALPS index) and left (left ALPS index) hemispheres respectively(Figure 1). An asymmetry index (AI) was calculated by AI=(Left-Right)/[(Left+Right)×0.5] to represent the asymmetric pattern. Meanwhile, correlation of DTI-ALPS index in both hemispheres with age, seizure duration and epileptic frequency were respectively explored via pearson’s coefficient(r).
Results：A total of 42 SLECTS and 42 health controls (HC) were enrolled and the demographic information is shown in Table 1. All participants are right-handed. Leftward asymmetry in DTI-ALPS was found in HC and RSLECTS patients. Both left DTI-ALPS index and right DTI-ALPS index of SLECTS patients were significantly decreased. Compared to contralateral DTI-ALPS index, the ipsilateral DTI-ALPS index was significantly decreased in SLECTS and RSLECT patients (Figure 2). The DTI-ALPS index positively correlated with age in HC. Meanwhile, DTI-ALPS index gradually decreased with seizure duration (Figure 3).
Discussion：In this study, SLECTS patients exhibited altered DTI-ALPS index, which could be triggered by glymphatic system dysfunction[9]. Altered DTI-ALPS index were more severe in ipsilateral than in the contralateral hemisphere. With prolonged seizures duration and increased seizures frequency, more metabolic products would be released, resulting in more severe blood brain barrier dysfunction leading to the dysfunction of glymphatic system[10]. Sustained hypertension after onset of seizure would weaken arterial pulsation, thus affecting the glymphatic system function by altering neurovascular coupling also an important reason[11]. In childhood, the blood brain barrier is underdeveloped, and as they grow, the function of the blood–brain barrier develops, so DTI-ALPS index positively correlated with age[12].
Conclusion：The SLECTS patients exhibited altered DTI-ALPS index, which could be triggered by glymphatic system function. Altered DTI-ALPS index were more severe in ipsilateral than in the contralateral hemisphere. Moreover, RSLECTS and LSLECTS patients exhibited different change patterns of the glymphatic system.
Acknowledgements
This study was supported by National Natural Science Foundation of China(82272618, 81971581) ,Natural Science Basic Research Plan of Shannxi(2022JQ-811) ,the Institutional Foundation of the First Affiliated Hospital of Xi'an Jiaotong University(2021ZYTS-04). Please address correspondence to Jian Yang, e-mail: yj1118@mail.xjtu.edu.cn and Xianjun Li, e-mail: xianj.li@mail.xjtu.edu.cn.References
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