Evaluation of subclinical seizure activity in patients with multiple sclerosis using electroencephalography

ABSTRACT Purpose: This study aimed to evaluate subclinical seizure activity that does not cause subjective or objective changes in consciousness or behavior which may be observed in patients with multiple sclerosis (MS) using electroencephalography (EEG). It was also investigated whether there was a relationship between subclinical seizures and disability levels, disease duration, MS treatments, depression and cognitive impairment. Materials and Methods: Relapsing Remitting Multiple Sclerosis patients who applied to Akdeniz University Faculty of Medicine Hospital, Department of Neurology, MS outpatient clinic between July 2023 and July 2024, who met the inclusion criteria, and who volunteered to participate in the study were included in the study. Subjects with subjective complaints and normal cranial imaging and neurological examination were selected as the control group. A total of 85 participants were inclueded in the study, 53 individuals with RRMS and 32 healthy controls. EEG recordings were performed twice in the MS group and once in the control group. Second EEG recordings of 8 patients in the MS group could not be performed due to patient requests. Demographic data (age, gender) of all participants and duration of disease, number of attacks and MS treatments of the patient group were recorded. During the examination, EDSS (Expanded Disability Status Scale) levels of MS patients were determined, and Beck Depression Scale (BDS) and Montreal Cognitive Assessment Test (MoCA) were applied to each participant. Findings: The mean age of the RRMS patients in the study was 37.40 years, while the mean age the control group was 40.50 years. 84.9% (n=45) of the patients were female and 15.1% (n=8) were male; the control group consisted of 81.3% (n=26) female and 18.8% (n=6) male subjects. The mean disease duration of RRMS patients was 8.15 years and mean EDSS score was 1.76. The mean MoCA score of the patient group was 25.11, and the control group score was 25.9; the mean BDI score of the patient group was 11,19, and the control group score was 9,91. There was no statistically significant difference between the two groups in terms of age, gender, educational status, employment status, MoCA and BDI scores. When the EEG results of the participants were examined, in the RRMS group, normal EEG findings were detected in 47 patients (88.7%), focal epileptiform activity in 2 patients (3.8%), slowing of background activity in 2 patients (3.8%) and frequency/amplitude asymmetry in 2 patients (3.8%) in the first EEG. When the control group EEG results were examined, normal EEG findings were observed in all participants. However, no statistically significant difference was found between the EEG data in the two groups (p>0.05). In the RRMS group, second EEG data could be obtained from a total of 45 patients due to the fact that 8 patients could not complete their second EEG recordings. Only 1 focal epileptiform activity (2.2%) was observed among the 2nd EEG results. Epileptiform activity was observed in 3 of 45 RRMS patients who completed the two planned EEG examinations, and the subclinical seizure frequency was detected as 6.66% in our study. However, the presence of EEG abnormalities could not be directly associated with cognitive impairment and depression. Conclusion: It is known that MS patients experience depression, cognitive disorders, and epileptic seizures due to demyelination and other pathophysiological processes. In addition, it is thought that patients may have subclinical seizures without causing objective or subjective symptoms and findings. This study shows that EEG examination can be used for subclinical neurological changes in RRMS patients. Further studies are needed to understand the clinical significance of EEG abnormalities. Keywords: Multiple Sclerosis, Subclinical Seizure, Electroencephalography, Cognitive Functions, Depression