The pathophysiology of PD sleep problems is unclear. Degeneration of major sleep control centers in the brainstem is a leading factor . In addition to dopaminergic medication, nocturnal akinesia, depression and restless legs syndrome, may contribute to sleep disturbances in Parkinson's disease .Previous studies linked dopaminergic impairment in the hypothalamus to sleep disturbances in PD.
Repetitive transcranial magnetic stimulation (rTMS), non-invasive magnetic stimulation of the cerebral cortex is utilized as non-pharmacological therapy in PD with varying degree of results on the motor symptoms. rTMS has also an impact sleep organization in healthy people both during and before sleep.
The effects of rTMS on sleep have been studied in PD in two previous studies, both of which applied HF over either the motor or parietal cortex. They reported improvement in sleep by subjective and objective measures. However, one of the studies found that the improvement seen on polysomnographic (PSG), the other study found improvement in actigraphic recordings. One sham-controlled trial of the effect of rTMS on sleep in patients with PD also revealed substantial placebo-related improvement on subjective questionnaires (i.e., Parkinson Disease Sleep Scale, Hamilton Depression Rating Scale, Unified Parkinson Disease Rating Scale), with sleep improvement found equally between active and sham stimulation groups . Interestingly, in this trial rTMS showed no changes recorded in actigraphy parameters.
Huang et al. 2018 examined the effect of LF rTMS over the parietal cortex in patients who had generalized anxiety disorder with comorbid insomnia and assessed Hamilton Rating Scale for Anxiety (HRS-A), and PSQI. In their trial, PSQI improvements were seen in active rTMS but not in sham stimulation, making this the second trial of a sham-controlled trial without pronounced placebo effect. Additionally, a positive correlation was seen between improvement in the HRSA anxiety scores and PSQI scores which could suggest that sleep improvement was associated with anxiety improvement. It was not known whether the improvement seen in insomnia and anxiety was independent, and whether rTMS really had an intrinsic role in sleep (Rosenquist and McCall 2019) In another study, Jiang et al. 2013 evaluated the effect of rTMS versus medication versus cognitive behavioral therapy in chronic insomnia. They performed the assessments with PSG and PSQI. Based on PSG findings, rTMS only showed superior improvement in stage 3 and rapid-eye movement sleep.
According to the above mentioned studies rTMS seems to have the ability to improve sleep disorders.
The literature in this area remains scarce, with few randomized clinical trials on rTMS and insomnia. Available studies have found mixed results, with some studies reporting subjective sleep improvement while objective improvement is less consistent.
Despite the significant prevalence of sleep disturbances in PD patients, rTMS's influence on sleep has not been objectively evaluated. To date, the exact mechanism by which rTMS is thought to influence sleep has yet to be fully explained particulary in PD.
The present study aimed to analyse the sleep disturbance in PD patients compared with normal volunteers and to objectively evaluate if rTMS has impact on sleep disorders or not in patients with PD.
