The Quantitative Retrospective Study In Grade Level Of Brain Dysfunction Induced By Head Injury (Ⅰ)

【Background】Evaluation of brain injury in clinical forensic medicine, by either assessing degree of brain damage or the level of disability, often involves the evaluation of brain function, including parameters for mental disorders, cognitive dysfunction and other consequences due to injury .The brain consists of millions of nerve cells, the functions of which are too many and complicated, and at the same time are influenced by several internal and external factors. The scientific evaluation of brain dysfunction after traumatic brain injury is a major and difficult research topic in forensic clinical medicine. At present, there is no definite way for complete objective evaluation, especially quantified evaluation. The Wechsler Adult Intelligence Scale (WAIS), is a classic intelligence scale used in clinical and forensic fields and has become the main tool for evaluation of intelligence. But it relies on the individual's words and external behavior performance or the result to infer the extent of the damage. The result, however, is influenced by certain subjective factors of the one being tested. In recent years, the Event-Related Potential (ERP) has been given more attention and has been widely applied in the forensic medicine field. ERP relies on the subject's psychological reaction or response to environmental stimuli, and thus the cognitive function of the cerebral cortex reaction. This study collected data from cases related to assessment of intelligence following brain injury from our institute .Electric potential technology (P300) combined with the'Chinese Adult Intelligence Quotient Scale'(IQ) Merriam -Webster revision was employed to assess the cerebral cortex cognitive functions and the determination of intelligence. For statistical analysis, factors such as age, time since injury, education level, degree of trauma were considered in order to establish an equation to evaluate brain dysfunction degree after craniocerebral trauma .Thus, a mathematical prediction model for such cases could provide an objective quantitative index for forensic and clinical work.【Objective】Study the relationship between event related potential IQ, age, time of injury, education level, brain injury level ,changes in electric potential P300 and brain function following craniocerebral injury. Combining the different parameters to find the relationship between the indexes and a comprehensive quantitative grading of brain dysfunction in head-injury patients.【Method】Using Vikingquest Evoked potential instrument producted by the American'Nicolet'company to detect the Event-related potential in 101 patients with craniocerebral injury, obtaining the amplitude and incubation period of P300 which is the component of the Event-related potential. With China's revised Wechsler Adult Intelligence Quotient Scale, the determination of intelligencewas carried out ,taking the following as reference :age, time of injury, disability level, the education level. To assign the level of disability as the trace standard for degree of brain dysfunction , all data were processed by SPSS15.0 software for Windows statistical analysis thus including'Analysis of variance','Chi-Square test'gradually discriminant analysis, etc.【Results】Values obtained for the examinee's P300, intelligence, age, time of injury, two compulsory test, the brain injury level, profession, surgical treatment, sex, education level before the injury are taken as variables and are further analyzed. Variable P300, IQ, age, reservation, and the remaining variables were chosen out,and then three different equations could be identified to point out mild grade'2', moderate as'1', moderate'2'.Using the above variables give an equation with a total accuracy of 70.5% for assessing dysfunction of the brain.【Conclusion】P300, IQ, age and other indicators are important markers to assess the extent of brain dysfunction. This study established a highly accurate rate equation which may be used in forensic expertise for evaluating the extent of brain dysfunction in brain injury .But during its application ,special attention should be paid to possible influence from both examiner and examinee.