Introduction: Periodic limb movements during sleep (PLMS), often characterised by repetitive dorsiflexion of the feet, show a strong interdependence with nocturnal blood pressure spikes (Cassel et al., 2016), as well as an established link to hypertension and other cardiovascular diseases (Chiaro and Manconi, 2019). Studies routinely stratify patients by periodic limb movement index (PLMI) (Drakatos et al., 2016; Xie et al., 2017; Mahmudova et al., 2022), however, there is currently no data linking the duration of individual contractions to cardiovascular outcomes. Here, we investigate the potential link between average limb movement duration and acute response in systolic blood pressure and pulse rate in patients with PLMS, and consider the implications for further cardiovascular risk stratification.

Methods: Ten patients with PLMS were identified retrospectively. Polysomnographic studies, including pulse rate and blood pressure data, were available in each case. For all patients, a single representative hour with the most limb movements during sleep was identified and analysed. Pulse rate and systolic blood pressure values were recorded 1-2 seconds prior to each limb movement, and again at their peak during the 10 seconds following conclusion of the movement. These values were then correlated against the duration of the respective tibialis anterior muscle contraction.

Results: This study cohort (7/10 male; mean age = 49.9 ± 22.4; mean BMI = 28.1 ± 7.2) showed a strongly positive correlation between the average limb movement duration and acute rise in systolic blood pressure (r = +0.74, p = 0.014). Conversely, there was little evidence of a correlation between average limb movement duration and change in pulse rate (r = +0.05, p = 0.882).

Conclusions: This study provides the first evidence linking average limb movement duration with acute cardiovascular response in patients with PLMS. Cardiovascular risk could be better stratified using the average limb movement duration alongside PLMI.