Periodic limb movements among persons with epilepsy: A retrospective polysomnographic study

Persons with epilepsy (PWE) frequently contend with disrupted sleep related to multiple seizure related as well as other factors like medications and comorbidities. Such disturbances often lead to fragmented sleep, which can adversely affect quality of life and compromise seizure management. Previous Although previous research has addressed conditions like sleep apnea and insomnia among PWE, less attention has been paid to periodic limb movements (PLMs), a requirement for diagnosis of the periodic limb movement disorder and also commonly observed in restless legs syndrome (RLS) as well as other conditions. This study aims to determine the prevalence and specific features of PLMs in PWE and to explore how these movements correlate with objective sleep measurements.

This investigation employed a retrospective chart review of consecutive adult patients diagnosed with epilepsy who underwent polysomnography at a tertiary-care sleep laboratory over a ten-year span. The control group consisted of individuals evaluated for possible obstructive sleep apnea, who were matched to cases based on age, sex, and the severity of sleep apnea. Patient records were initially identified using keywords related to "epilepsy" or "seizures." Epilepsy diagnosis was confirmed through detailed chart review, which also yielded clinical details likety duration of epilepsy, seizure classification, and antiseizure medication usage. Sleep parameters such as sleep efficiency, spontaneous arousal index, periodic limb movement index, periodic limb movement with arousal index, and apnea-hypopnea index were extracted from archived polysomnography reports. The subsequent analysis was carried out using descriptive statistical methods using RStudio version 4.4.1.

A total of 152 relevant patient records were found in the database. Of these, 61 patients with epilepsy (mean age 41.4 ± 17.2 years, including 31 females) met the inclusion criteria and were matched with 61 patients suspected for OSA. Within the epilepsy cohort, 43 patients experienced focal-onset epilepsy while 16 had generalized epilepsy. 25 patients were prescribed two or more antiseizure medications, and 12 were categorized as medically refractory. PLMs were detected in 23 % of patients with epilepsy compared to 26 % in the control group, with mean PLMI values of 6.1 ± 16.8 and 8.8 ± 20.7, respectively. The PLMAI was also similar between the two groups (0.5 ± 1.0 vs. 1.1 ± 2.4). Other sleep parameters, including the mean AHI (16.0 ± 20.0 in the epilepsy group vs. 19.7 ± 19.4 in the control group), did not exhibit significant differences between groups. Within the epilepsy cohort, the only factor linked to the presence of periodic limb movements was older age, with no observed association with seizure type, number of antiseizure medications, or seizure control.

PLMs are a frequently observed phenomenon in polysomnographic studies of PWE and are predominantly related to advancing age. Given the comparable indices of periodic limb movements in both the epilepsy group and an age- and sex-matched cohort with obstructive sleep apnea, the findings suggest that obstructive sleep apnea might be a major contributor to the periodic limb movements seen among PWE.