Sleep during low-frequency repetitive transcranial magnetic stimulation is associated with functional improvement in upper limb hemiparesis after stroke

Many studies have reported that repetitive transcranial magnetic stimulation (rTMS) is beneficial for post-stroke patients with upper limb hemiparesis. It was reported that application of rTMS during sleep could possibly strengthen neural plasticity. The purpose of this study was to investigate the relationship between sleep during low-frequency rTMS session and improvement of motor function in affected upper limb in post-stroke patients after inpatient rehabilitation combined with rTMS using the bispectral index (BIS) monitor. During 15-day hospitalization, each patient received rTMS and intensive occupational therapy. Low-frequency rTMS with 1 Hz was applied over the contralesional motor cortex. During rTMS session, adhesive sensor was put on each patient’s forehead and connected to the BIS monitor. The mean score for the maximum change of BIS values during each rTMS session (ΔBIS) was calculated. We regarded the patients with and over 10 of mean ΔBIS as Asleep group and under 10 as Awake group. Fugl-Meyer assessment (FMA) and Action Research Arm Test (ARAT) were evaluated on admission and discharge. Awake group included six patients and Asleep group included seven patients. There was no significant difference in clinical characteristics and in increase of FMA between two groups. Asleep group was significantly superior to Awake group in the increase of ARAT (p < 0.05). There was a significant correlation between the mean of ΔBIS and increase of ARAT (ρ = 0.78, p = 0.002). Sleep during low-frequency rTMS may contribute to improvement of motor function in the affected upper limb.