Objective To study the advantages and procedure of telovelar approach for resection of the lesion in the fourth ventricle. Methods Telovelar approach to the fourth ventricle was executed in 17 cases. Among these patients, seven were females and 10 were males. The age ranged from 5 years to 49 years with mean age of 26.6 years. Pathologically, there were 5 medulloblastomas, 5 ependymomas, 2 epidermoids, 2 brain cysticercosis, and 3 choroid plexus papillomas. During the operation, the medullotonsillar space of the cerebellomedullary fissure and the urulotonsillar space were sharply dissected to release the tonsils from uvula and medullar oblongata bilaterally. According to the size of the neoplasm, the tela or both tela and velum were incised. The fourth ventricle was exposed adequately and the lesion was removed. All operations were performed with the help of microscope. The dura was sutured securely. Results The space occupying lesions were removed totally in all cases and all patients recovered very well, and threre was no mortality or serious disability. With 3 to 21-month follow-up in 11 cases, no death or serious disability was found, and the CT or MRI in 8 patients showed no recurrence. Conclusion The telovelar approach can provide adequate exposure to remove the lesion in the fourth venticle. The inferior vermis need not be incised, so a minimum amount of brain tissue was injured, and postoperative complication is decreased.

Objective To study the role of VEGF on the growth of hypertensional saccular aneurysm and its mechanism. Methods Twenty-four SD rats were divided into 2 groups randomly (A and B, each with 12 rats). Saccular aneurysms of the carotid artery were reproduced by treatment of initial segment of the external carotid artery (1mm long) with elastase. In group A, the posterior branches of both renal arteries were ligated in order to produce marked elevation of blood pressure. In Group B hypertension was not produced to serve as the control group. After 8 weeks, the blood pressure and the size of the aneurysms were measured. Then formalin was infused into the arteries for fixation, and aneurysms were resected. The expression of vascular endothelial growth factors (VEGF) in aneurysmal wall was assessed with immunohistochemical analysis. Results The size of aneurysms: after 8W, significant difference was found between A and B group (P

Objecive To reproduce an experimental model of aneurysm more which is simulating intracranial aneurysm pathomorphologically to serve further research on aneurysm. Methods Saccular aneurysms of the carotid artery were reproduced by corrosion of initial segment of the external carotid artery (1mm long) with elastase in 10 SD rats. After 4 weeks, the size of the aneurysms was measured. Then the aneurysms were fixed by intra-arterial perfusion of formalin and were resected. The pathological characteristics were evaluated with hematoxylin-eosin and Van Gieson staining. Results The pathological features of the experimental aneurysms showed that the tunica intima was interrupted, the elastic and muscular layers were disrupted or disappeared, replaced by proliferative collagen fiber, simulating natural aneurysms. After 4 weeks, the size of aneurysms was larger compared with that in the beginning (P

Objective to study the effect of blood pressure on the enlargement of saccular aneurysm and its mechanism. Methods Forty-eight SD rats were divided into 3 groups randomly(A, B and C; n=16 in each group). Saccular aneurysms of the carotid artery were induced by corrosion of the initial segment of the external carotid artery (1mm long) with elastase. In group A, the posterior branches of both renal arteries were ligated in order to produce a marlced blood pressure elevation. In group B, only unilateral renal artery was ligated, and a moderate hypertension was produced. In group C high blood pressure was not produced to serve as the control group. After 2 and 8 weeks, the blood pressure and the size of the aneurysms were measured. Then the aneurysms were fixed by intraarterial perfusion of formalin and were harvested for examinations. The expression of basic fibroblast growth factor (bFGF) in aneurismal wall was determined by immunohistochemical analysis. Results Two weeks after the beginning of the experiment, there was no difference in size of aneurysm among the 3 groups. But after 8 weeks, significant difference in aneurysmal size was found between group A and the other two groups. The expression of bFGF in group A was stronger than that in group B and C. Conclusion The elevation of blood pressure and enhancement of bFGF expression in aneurismal wall play an important role in enlargement of the aneurysm.

Objective To investigate the iNOS expression in cerebral aneurysm tissue, and the effect of selective iNOS inhibitor aminoguanidine on experimental cerebral aneurysm formation and serum NO production. Methods Fifty SD rats were divided into 3 groups randomly. To reproduce the aneurysm model, 40 adult male rats (weight, 250-300g) were subjected to ligation of the left common carotid artery and the posterior branches of both renal arteries. One week after the operation, 1% saline was given for drinking to substitute plain water. Each rat received an intraperitoneal injection of aminoguanidine (100mg/kg)(group A, n=20) or normal saline (group B, n=20) beginning in the morning of postoperative day(POD) 1 through POD 150. Group C rats received no operation to serve as the control group (n=10). Arterial wall at the bifurcation of the right anterior cerebral artery and olfactory artery as well, as serum were harvested after 5 months. Blood pressure was measured before the experiment and 5 months after the experiment procedure. NO levels were indirectly quantified by measuring nitrate levels. The incidence of formation of aneurysm, pathological findings and expression of iNOS in aneurysmal wall were evaluated with HE staining and immunohistochemical analysis. Results Selective iNOS inhibitor aminoguanidine could significantly inhibit the formation of aneurysms and lower serum levels of nitrate. The pathological features of the experimental aneurysms were similar to that in human, including discontinuation or disappearance of tunica intima, thinning or disappearance of the elastic and muscular layers, and substitution of artery wall by a layer of fibrous connective tissue. iNOS immunoreactivity could be seen in the smooth muscle cells of the intimal pad and distal portion of the newly formed aneurysm. Conclusion Cerebral aneurysm can be induced in rats by alteration in hemodynamics, and it is related to formation of local expression of iNOS and high NO level.

Objective To summarize the experiences of microsurgery for treatment of middle cerebral artery aneurysms (MCAA). Methods The clinical data of 35 patients with MCAA treated by microsurgery in General Hospital of PLA from 2004 to 2008 were retrospectively reviewed. Of them there were 20 males and 15 females, aged 18 to 72 years with a mean of 40 years. Of the 35 patients, subarachnoid hemorrhage occurred formerly in 22, intracerebral hemorrhage occurred in 11 and subdural hematoma in one patient. The MCAA located in the middle cerebral artery trunk in 10 patients, at the bifurcation in 20 patients (including one patient with 2 MCAAs), and in the distal segment in 5 patients. MCAA located on the left side in 13 and on right side in 22 patients. There were 7 patients with giant aneurysms, 11 with large aneurysms and 17 with small aneurysms. Microneurosurgery was performed in all cases, and different approaches were taken according to the locations of aneurysms. Superior temporal gyrus approach was conducted in 3 patients with giant intracerebral hematoma. Bypass of superficial temporal artery to middle cerebral artery was performed before occlusion of the afferent artery in one patient with giant aneurysm. Bypass with saphenous vein to middle cerebral artery was performed in another patient with giant aneurysm. Results The giant and large MCAAs consisted of 51.4% of all cases. Excellent outcomes were achieved in 20 patients, no marked change in 12 patients, and post-operative complications were observed in 3 patients. No perioperative death occurred. Conclusions Giant and large aneurysms are more common in middle cerebral artery aneurysms. Proper surgical approaches based on different situations during operation should be considered to achieve satisfactory outcome.

Objective To improve the diagnosis and treatment of neurenteric cyst. Methods The clinical manifestations, MRI characteristics and surgical results of 11 cases of intraspinal neurenteric cysts were analyzed. Results Positive pathological signs and paresis appeared in all cases, and radicular pain in 9 cases. The symptoms were episodic in 2 cases whose courses were more than 3 years. MRI could clearly demonstrate the exact extension of the cyst and the surrounding structures. These cysts showed as slightly long T 1, long T 2 homogeneous signal on MRI. Their neurological functions improved steadily after complete resection in 8 cases, subtotal resection in 3 cases. Conclusion Neurenteric cysts are rare congenital lesions, often associated with vertebral anomalies and occurred at subdural cervical location, anterior to the cord. MRI is a more effective and convenient method for neurenteric cyst image investigation. Total or subtotal resection of neurenteric cysts with subsequent recovery in neurological function is usually possible.

Objectives To investigate the neuroprotective mechanism of vagus nerve stimulation ( VNS) by stimulating the vagus nerve in ischemic cerebral tissue in a rat model of transient focal cerebral ischemia. Methods Twenty-six adult male Sprague-Dawley ( SD ) rats were randomly divided into sham operation group (n=6),model group (n=10),and VNS-treated group (n=10) . The model of rat transient focal cerebral ischemia was induced by the intraluminal suture method. At 30 min after modeling,the right side neck VNS in the VNS-treated group was stimulated ( stimulus intensity 0. 5 mA, interval 0. 5 ms, frequency 20 Hz),once every 5 min within 1 h,and once for 30 s. The model group repeated the steps of the VNS-treated group,but did not stimulate. The sham operation group repeated the experimental steps,but it neither embolized the vessels nor stimulated nerves. The changes of cerebral blood flow were monitored with a laser Doppler flowmeter. The rats were sacrificed after 24 h. The expressions of interleukin 6(IL-6) and caspase-3 in brain tissue were determined by immunohistochemistry staining. The neuronal apoptosis was observed by the in situ end-labelling technique. Results ( 1 ) Compared with the sham operation group, the number of positive cells of IL-6,caspase-3,and the numbers of neuronal apoptosis in the model group were significantly increased (20. 7 ± 5. 0 cells/HP vs. 2. 3 ± 1. 0 cells/HP,44. 5 ± 9. 5 cells/HP vs. 0,30. 9 ± 9. 0 cells/HP vs.0).Thereweresignificantdifferences(P<0.05).(2)Comparedwiththemodelgroup,thenumber of positive cells of IL-6(10. 9 ± 3. 7 cells/HP),the caspase-3 (18. 9 ± 6. 7 cells/HP),and the numbers of neuronal apoptosis (14. 0 ± 5. 2 cells/HP) in the VNS-treated group decreased significantly. There were significant differences (P<0. 01). (3) Before and after modeling,there were no significant differences in cerebral blood flow in various periods between the model group and the VNS-treated group (P>0. 05). Conclusion The neuroprotective mechanism of VNS for cerebral ischemia may be associated with the inhibition of neuronal apoptosis and decreasing inflammatory response. It may not be associated with the changes of cortical cerebral blood flow.

Objective To investigate the neuroprotective effect of vagus nerve stimulation ( VNS) on a model rat of focal cerebral ischemia. Methods A total of 42 adult male Sprague-Dawle ( SD) rats were randomly divided into a sham operation group (n=10),a model group (n=16),and a VNS-treated group ( n = 16 ) . Each group was randomly redivided into 2 subgroups:left VNS subgroup and right VNS subgroup. A model of focal cerebral ischemia (2 h) in rats was induced by the intraluminal suture method. At 30 minutes after modeling, the VNS-treated group received cervical VNS, the stimulation intensity was 0. 5 mA,the interval was 0. 5 ms,and the frequency was 20 Hz. Stimulation was once every 5 min within 1 h and each lasted for 30 s. The model group did not give any stimulation. Neither blood vessels were embolized nor were the nerves stimulated in the sham operation group. The changes of somatosensory evoked potentials ( SEP) on the lesion sides during operation were monitored. At 24 h after modeling,the neurobehavioral scores were performed. The rats were sacrificed,and their brain infarct volume was measured. Results (1) During the stimulation of left VNS in rats,the neurobehavioral scores of the sham operation group,model group and VNS-treated group were 0. 4 ± 0. 2,9. 5 ± 0. 4,6. 4 ± 0. 3,respectively;during the stimulation of right VNS in rats,the neurobehavioral scores of the 3 groups were 0. 6 ± 0. 2,9. 3 ± 0. 4,and 6. 9 ± 0. 4,respectively. There were significant differences between the scores of the model group and those of the other 2 groups (P<0. 05). (2) Compared with the model group,the brain infarct volume of the VNS-treated group was reduced ( stimulating the left VNS of the 2 groups was 120 ± 7 and 56 ± 7 mm3 respectively;stimulating the right VNS was 115 ± 10 and 54 ± 8 mm3 respectively ) . There were significant differences ( P <0. 05). (3) Compared with the sham operation group and the VNS-treated group,the SEP N1 amplitude of the model group was decreased significantly and the P1 latency was prolonged significantly. There was significant difference (P<0. 05). (4) There were no significant differences in the stimulation of the left or right VNS in the VNS-treated group among the infarct volume, neurobehavioral scores, SEP amplitude,and latency (P>0. 05). Conclusion No matter whether to stimulate the left or right vagus nerves, they both have neuroprotective effects on ischemic brain injury, and there was no significant difference on the action effects.

Objective To evaluate the reliability and accuracy of three-dimensional digital fusion anatomy in the preoperative evaluation and therapeutic strategy choice of intracranial tumors.Methods MRI scan,including regular MRI,MRA,MRV and DTI,were performed in 87 case.Then tumor themselves as well as tumor-associated structures were reconstructed and fused through iPlan 2.6 software.Based on the reconstructed images,therapeutic strategy were established,preoperative and intraoperative imags were compared.Results The digital reconstruction were successfully finished in all cases.Meanwhile,digital images,originally radiological images and actual images matched well.No approach-associated complication were met in our series.Among tumors in the convexity,the relationship of the reflux veins and the tumors were divided into three types:anterior(12 cases),posterior(19 cases) and overriding(3 cases).All of the relationships were seen in the preoperative fusion image,and the veins were all effectively protected during operation.The tumor-associated arteries could be pushed or wraped by the tumors,and the three-dimensional fusion image could provided their virtually aberrant pathway as well as their relationship with tumor.During microsurgical managment of tumors in the deep brain parenchyma,safe approach were found with the help of comprehensive understanding of the tumors and their adjacent structures.Conclusion Three-dimensional digital fusion anatomy can vividly and accurately display full rang of information about the tumor,and facilitate tumor treatment safely.