答复：  您好！脑干位于颅后窝内，俯卧于颅底蝶鞍斜坡上，上接间脑，下端在枕骨大孔处延续为脊髓，脑干向下向上分为延髓、脑桥和中脑三部分。脑干为第Ⅲ～第Ⅻ颅神经的起源地，与嗅神经及视神经有传导反射联系，是上行及下行的长束必经之处。脑干的网状结构中有呼吸及循环中枢，其网状激动系统与意识有密切关系。脑干症状复杂多样，其特点是:病变同侧的周围性颅神经麻痹和对侧的中枢性偏瘫及偏身感觉障碍—交叉性麻痹。
胶质细胞瘤发病原因目前不清楚，和年龄关系不大。但是发病率最高，约占40.49%，综合发病年龄高峰在30-40岁，或10-20岁。大脑半球发生的胶质瘤约占全部胶质瘤的51.4%，以星形细胞瘤为最多，其次是胶质细胞瘤和少枝胶质细胞瘤，脑室系统也是胶质瘤较多的发生部位，占胶质瘤总数的23 .9%，主要为管膜瘤，髓母细胞瘤，星形细胞瘤，小脑胶质瘤占胶质瘤总数的13%，主要为星形细胞瘤。如果有脑干胶质瘤的可能是由如下几组症状。 中脑症状（1）眼球运动障碍:中脑的动眼神经核、滑车神经核及四叠体三个部分之一或全部发生病变时， 出现动眼神经及滑车神经的麻痹，两眼球上视、下视瘫痪，即Parinaud综合征。（2）感觉障碍:中脑病变同时侵及内侧丘系及脊髓丘脑束， 则出现病灶对侧半身各种感觉障碍，包括痛、温、触觉及深感觉障碍。（3）运动障碍:中脑一侧病变时出现病灶对侧中枢性面神经、舌下神经及中枢性上下肢瘫痪。中脑的大脑脚发生病变时，常侵及动眼神经的髓内或髓外根，而出现Weber综合征，即病变侧动眼神经瘫痪和对侧中枢性瘫痪。中脑红核、黑质损伤，则出现不随意运动，肌张力减低或增高。出现去大脑强直时，全身肌张力显著增高。（4）瞳孔异常:动眼神经的缩瞳核及其纤维受损，病侧瞳孔散大、对光反射减弱或消失。（5）Claude症候群:中脑背侧部近于大脑导水管处病变，同时伴有小脑结合臂的损害时，表现同侧动眼神经麻痹，对侧上下肢共济失调等小脑症状及体征。（6）精神及睡眠障碍:中脑被盖部病变损害了中脑网状结构，表现为中脑幻觉。患者在黄昏时引起幻视或感觉性幻觉。如看到活动的动物、人体、瑰丽景色，患者自知力缺如，并常以此为乐，可伴有嗜睡、感觉障碍。

脑桥症状（1）颅神经症状:脑桥病变引起的三叉神经症状以病灶侧面部感觉障碍为主，角膜反射减低或丧失，同侧咀嚼肌萎缩且肌力弱，张口下颌偏向患侧，外展神经麻痹，眼球内斜。（2）感觉障碍:感觉障碍程度不一，有的完全缺失，有的轻度减退。股体感觉障碍及面部感觉可以呈交叉状态。肢体感觉症状又表现为分离性感觉障碍。（3）运动麻痹:多于病灶对侧出现偏瘫。脑桥下部病变时，病侧出现面神经麻痹，对侧出现偏瘫，同时病灶侧尚有外展神经麻痹。（4）小脑症状:小脑症状为为脑桥病变重要的症状之一 ，脑桥与小脑关系密切，脑桥病变时病灶侧出现共济失调及其他小脑症状。（5）精神及睡眠障碍:脑桥病变因损伤脑干网状结构可出现精神障碍、智力下降及睡眠障碍，起初淡漠、嗜睡、悲痛易哭、继之则好动，语言讷吃。

延髓症状群（1）肢体瘫痪:延髓锥体束交叉上方病变时，病灶对侧上下肢出现中枢性瘫痪，伴肌张力增高，腱反射亢进，锥体束征阳性。锥体交叉处病变时，出现上下肢交叉性瘫痪，病侧上肢瘫，对侧下肢瘫。（2）感觉障碍:延髓病变损伤感觉传导路时，多出现病变对侧肢体的分离性感觉障碍。病灶损害双侧内侧丘系时，可出现双侧深感觉障碍。（3）颅神经障碍:延髓病变时，可出现第Ⅺ、Ⅹ、Ⅺ、Ⅻ对颅神经的损害症状。表现为吞咽困难、声音嘶哑、舌肌萎缩等。（4）小脑症状:延髓病变侵及绳状体，则发生同侧小脑症状，表现为肌张力减退，平衡不稳、患者向病侧倾倒。（5）植物神经症状:一侧延髓病变可出现霍纳氏征， 即眼球内陷、瞳孔及眼裂变小。常伴有汗液、唾液分泌过多。延髓呼吸中枢损伤可出现呼吸节律紊乱，甚至出现呼吸停止。心血管中枢障碍则表现为心动节律紊乱及血压升高。（6）精神症状:延髓病变的患者可出现阵发性焦虑，且常于夜间发作。有的出现幻视及错认。

治疗由于目前的显微神经外科技术比较发达，能够进行一部分病人的全切手术。 同时采用节拍式化疗和血管抑制治疗。是可以对一部分患者进行根治的。

下面是一些详细的脑干区域的解剖结构和功能：
Hopefully, all of you know where the spinal cord is and lots about the organization of the various ascending and descending pathways. Now we will move rostrally into the brain stem. If you look at the drawings below you will see three MRIs in the middle column. The poor little brain stem is so dwarfed by other brain structures that I have had to enclose it with a white box and point to it with a white arrow!!!! However, I have added schematic enlargements of the boxed in areas. Again, as in the spinal cord, ventral is up and dorsal is down and the right side of the patient’s brain is on your left.

  The figure below on the right shows the entire ventral surface of the brain stem. The lines and arrows connecting the ventral view with the three MRI images are to help you understand what is left and right. Do not worry about the bumps, grooves and nerves shown on this ventral view, that will come later.  Right now just orient yourself!!

Both the dorsal and ventral surfaces of the brain stem are shown below.  We already know what is right and left on the ventral view.  Now, take the page out of your notebook and fold it along the dotted line (yes, this is medical school!) and you can see that what lies beneath (is dorsal) the right side of the ventral aspect of the brain stem is the right side of the dorsal aspect of the brain stem, and what lies below the left side of the ventral aspect of the brain stem is left side of the dorsal aspect of the brain stem. 

Like in the spinal cord, in an axial MRI section of the brain stem ventral is up and dorsal is down. Again we will follow tradition (all neuro textbooks!) and “flip” the section so ventral is down and dorsal up. However, make sure to keep the right/left designation of the axial section MRI.  That is, the right side of the patients brain is on your left.

 

As mentioned earlier, the brain stem includes the (1) medulla, the (2) pons and the (3) midbrain. The brain stem contains 10 cranial nerves, and most of the motor and sensory systems pass through this important region. It is a relatively small region (approximately 7 cm long) that links the forebrain (i.e., cerebral cortex) and the spinal cord and all messages going between the two areas must go through the brain stem.

Details regarding the organization of the brain stem will be presented by discussing the nuclear groups and fiber tracts that are present at 10 different caudal to rostral levels.  In each of the ten levels, the tracts (fibers) are drawn in black. Therefore, the nuclei (cell bodies) are the clear spaces. The drawing below shows a rough approximation of the location of where the 10 levels are cut on a ventral view of the brain stem. The following ten pages show drawings of these levels and above each level is the appropriate MRI image.