Objective: To evaluate the influence of superficial needling on electroencephalogram (EEG) in patients with insomnia by using nonlinear kinetics measure.
Methods: Six patients (3 male and 3 female) suffering from insomnia for more than a month were recruited in the present study. EEG data before and during superficial acupuncture stimulation of Shangen point (the midpoint between the bilateral inner canthus) was recorded using an electroencephalograph for analyzing the correlation dimensionality (D 2) and approximate entropy (ApEn) of different cerebral regions.
Results: During superficial needling, the D 2 data of the right-forehead (Fp 2), anterior area of the left temple (F 7) and the anterior region of the right temple (F 8) were significantly increased (P<0.05), and ApEn data at the right anterior forehead(Fp 2), left occipital region (O 1), and F 8 region markedly decreased relevant to pre-acupuncture (P<0.05). Both paring test and trend analysis of D 2 data showed no significant changes. Only an obvious increase of D 2 was found in the Fp 2 region, suggesting a coherence of EEG activities in stability and synchronization during acupuncture treatment. Clustering analysis of D 2 data of various cerebral regions displayed a relatively concentrated tendency, particularly in the Fp 2, the right forehead (F 4) and F 8 regions. Factor analysis of ApEn data showed a significant change in Fp 2, F 8, O 1 and right occipital (O 2) regions. It suggests that during superficial needling stimulation of Shangen point, the EEG signals were lowered in complexity, and improved in synchronization, stabilization and ordering, favoring sleep at last.
Conclusion: Superficial needling of Shangen point can make the EEG signals synchronized in insomnia patients, suggesting an improvement of sleeping.
Keywords: Approximate entropy; Correlation dimensionality; Electroencephalogram; Insomnia; Nonlinear dynamics; Superficial acupuncture stimulation.