There are many causes for persistent vegetative state (PVS).The brain injury, especially brain stem injury, is the most common cause resulted in the PVS. According to the traditional concepts , the course of PVS is longer. The curative effect and prognosis are not so good. So,some medical workers and families are not very active in treating PVS. That is the reasons why the study on PVS has not been made a great breakthrough so far.The establishment of the models of PVS is a prerequisite to the experimental study. In the recent y ears, the reports on the models of PVS couldn't been popularized because of the poor replication or of the great difference between the conditions of the clinical patients and the experimental studies. In this experiment, a model of brain stem injury is initial established by filling water into the a rubber sac between epidural and cranium.Part I The establishment of the models of PVS in cats200 cross-breed cats weighing about 2.26?.39Kg each used in this experiment were divided randomly into normal control group (10 cats), sham-operation group (10 cats) and PVS group (180 cats). The cats were treated with nothing except the anaesthesia in the normal control group. The sham-operation groups were only made a cranium hole with a diameter of 1 x1 cm2. In PVS groups,the skin and temporalis were cut and made a cramium hole with 1x1 cm2 diameter on the right side of 1.5 cm sagittal suture and 0.5 cm before the lambdoid suture. A rubber sac was put into the area of temporal-occipital, which located at the middle cranial fossa.The rubber sac was poured into water with amout of 0.5~2ml untill the right pupil was enlarged for 6 hours.The brain stem was injuried by the high pressure rubber sac with water.The sacs were removed 6hours later. After the surgery, the cats were put into the animal house. The animals keep at the respiratory tracts being unobstructed and normal nursing and feeding. The pupils, intracranial pressure, respiration, heart rate, and blood pressure etc were monitered during and after the operation, and the postoperative neural reflection was examined.The standards of PVS evaluated according the basis of 1996 Chineses acute medical association. And we used this standard was modified according to the characteristics of the cats. The results of establishing the models:1 The models was lasted 56 days averagely;2 66 cats were successfully induced the PVS, and the success rate was 36.7% (66/1803 The death rate was 62% (111/1804 The incidence rate of complications was 79.4%(143/180),and the common complications were mistake-suck-in,intracranial hemorrhage,over-anesthesia and epliepsy ,et al;Conclusion:The PVS model induced with rubber water sac in the experiment hasthe similar pathogenesis of epidural hematoma in the clinic condition. The mechanism of this model may associated with increased intracranial pressure and brain stem shift, which resulted in the brain herniation,injury the mesencephalon and eventully long time coma-PVS. Compared with other models, this one has a high success rate, possible palinesthesia, easy replication,simple establishment and similarity both the clinical conditions of the patients and the experiment. This model can be used in studies for basis experiment and treatment.Part II the relative basis studies on the models of PVS in cats30 cats were^used in this part of experiment. It includes normal control group(10 cats), pseudo-operation group (10 cats) and PVS groups(10 cats) produced by our experiment. The levels of DA in cerebrospinal fluid and serum were detected with high-performance-liquid-chromatography and electric-chemical-detector (HPLG-ECD) in the cats.The morphologic change of dopaminergic neurons in mesencephalon were studied with immunohistochemicaly method for tyrosine hydroxylase (TH), and the animals were momitored by EEG ^ SEP, CT and MRI.Results:1.The level of DAin cerebrospinal fluid (83.34+21.21) in PVS cats was evadent