title: Excitability of the central masticatory pathways in patients with sleep bruxism.
abstract: Since sleep bruxism (SB) is defined as a stereotyped movement and mainly associated with rhythmic masticatory muscle activity, the aim of this study was to get a better understanding on the subcortical and cortical networks related to the excitability of the central masticatory pathways in SB patients. Of 26 SB patients (12 females and 14 males; mean age: 24.9±4.0 years) and 30 normal subjects (18 females and 12 males; mean age: 24.1±3.1 years) selected, the motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) in masseter muscles, and the masseter inhibitory reflex (MIR) elicited by magnetic stimulation with single and double-shock techniques were studied. The MEPs elicited by TMS were similar in both SB patients and normal subjects. As for the MIR elicited by single magnetic stimulation, the latency and duration of the early silent periods (SP1) between the two groups were similar; but in 5 patients the late silent periods (SP2) was absent, and this difference in the frequency of absence of the SP2 between SB patients and normal subjects was significant; with double-shock technique, the recovery of SP2 was significantly lower in SB patients compared to normal subjects. These results suggested an abnormal excitability of the central masticatory in SB patients; and it is also indicated that SB may be mainly under the influence of brainstem networks rather than that of cortical networks.
authors.affiliation: Laboratory of Oral Biomedical Science and Translational Medicine, School of Stomatology, Tongji University, Middle Yanchang Road 399, Shanghai 200072, PR China.
authors.forename: Huang
authors.initials: H
authors.lastname: Huang
authors.affiliation: Laboratory of Oral Biomedical Science and Translational Medicine, School of Stomatology, Tongji University, Middle Yanchang Road 399, Shanghai 200072, PR China.
authors.forename: Yu-Han
authors.initials: YH
authors.lastname: Song
authors.affiliation: Shanghai Mental Health Center, School of Medicine Shanghai Jiaotong University, Shanghai 200030, PR China.
authors.forename: Ji-Jun
authors.initials: JJ
authors.lastname: Wang
authors.affiliation: Shanghai Mental Health Center, School of Medicine Shanghai Jiaotong University, Shanghai 200030, PR China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Laboratory of Oral Biomedical Science and Translational Medicine, School of Stomatology, Tongji University, Middle Yanchang Road 399, Shanghai 200072, PR China. Electronic address: weicai_liu@tongji.edu.cn.
authors.forename: Wei-Cai
authors.initials: WC
authors.lastname: Liu
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D001933:Brain Stem / Q000503:physiopathology; D016022:Case-Control Studies; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000503:physiopathology*; D009434:Neural Pathways / Q000503:physiopathology*; D012018:Reflex; D020186:Sleep Bruxism / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation
keywords: Bruxism; Magnetic stimulation; Masseter inhibitory reflex; Motor evoked potentials; Transcranial magnetic stimulation