Feature Extraction Of Laser-evoked Brain Responses And Its Application On Postherpetic Neuralgi A Patients

Pain,as one of the most common clinical symptoms of various diseases,is deemed as the fifth vital sign of human body equivalent to breathing,pulse,blood pressure and body temperature.Pain has enormous aversive effects on psychological(e.g.,anxiety and depression),physical(e.g.,decreased immunity,autonomic nervous disorders,and pathological remodeling of the central nervous system)aspects of human health accompanied by a variety of complications,leading to the damage of work efficiency and the quality of life.According to the statistics From the Chinese Medical Association of Pain,about 30% of adults(at least 100 million)suffer from chronic pain in China.It can be seen that pain,especially chronic pain,has become a public health problem attracting extensive attention.As a prototypical kind of chronic pain,post-herpetic neuralgia(PHN)is defined as the most common chronic pain syndrome of acute herpes zoster infection,lasting at least 1 month.Because of its significant morbidity and long disease course,PHN has profound impacts on patients' health and quality of life.However,PHN can be caused by various factors,and there is still a lack of adequate understanding of PHN pathophysiology and psychological mechanism,leading to unsatisfactory treatment efficacy.Therefore,it is crucial to explore the pathophysiology and psychological mechanism of PHN to develop an early and optimal intervention for susceptible population of PHN.Thus we may be able to relieve pain,shorten the onset time,and reduce the incidence of complications in PHN patients based on the neuropathological mechanism of.If so,it will be extremely important for clinical practice and society.In recent years,laser-evoked potentials(LEPs)have been widely used in basic research and clinical applications of pain.Laser stimulator can selectively activate A? fibers and C fibers,eliminate tactile interference,and has the advantage of precise localization and controllable energy.Additionally,EEG technique can record weak electrical signals on the scalp surface,which can help obtain reliable electrophysiological parameters of pain.Therefore,we explore the PHN mechanism in pathology,physiology and psychology aspects based on the feature extraction of LEPs.In the current study,two experiments were conducted.In Experiment 1,EEG data were collected from 107 healthy subjects,and features of components of LEPs was extracted using advanced methods of EEG data analysis.The main results were as follows:(1)C-LEPs can be clearly detected in the presence of A?-LEPs;(2)Early responses of C-LEPs,such as C-N1 can be extracted from a single subject;(3)The latency of C-N1 was positively correlated with that of C-N2 and C-P2,and the amplitude of C-N1 was positively correlated with that of A?-N1;and(4)The stimulus intensity affected the amplitude of A?-N1 and C-N1 significantly.In Experiment 2,twenty-nine PHN patients were recruited from Daping Hospital Pain Department.Using McGill Pain Questionnaire,somatosensory test(including pain perception and tactile perception)and a series of psychological scales,we conducted a multi-source assessment from pathology,physiology and psychology aspects on patients' health condition.The results showed that:(1)the pain perception of PHN patients was not affected by the focus of infection;(2)the abnormalities of the somatosensory system threshold affect the pain perception of PHN patients.In other words,the sensory deficits and the small-fiber damage of PHN can be regarded as diagnostic indicators of the PHN severity;(3)the damage of the pain transmission system affect the pain perception of PHN patients,that is,the LEPs can be used as a diagnostic indicator of the damage of pain transmission system;(4)the mental state of PHN patients,such as the anxiety and sleep disorders,can affect their pain perception.In conclusion,we verified thecomponents in A?-LEPs and extracted an early response of C-LEPs(e.g.,C-N1),providing evidence to support the application of the LEPs on the investigation of the mechanisms of peripheral and central nervous system for nociceptive processing.We further explored the mechanism of PHN from pathophysiology and psychological aspects based on the extraction of LEPs.These findings not only provide an effective theoretical basis for the diagnosis and classification of clinical chronic neuropathic pain,but also suggest that it is necessary for medical workers to take account of several factors relevant to PHN,such as patients' deficits of the sensory nervous system,quality of life,and physical and psychological state,therefore optimizing the treatments for chronic pain.