腰椎穿刺檢查
(一)適應(yīng)證
1.了解腦脊液成分和壓力,進(jìn)行診斷及鑒別診斷。
2.鑒別腦震蕩、腦挫裂傷,有蛛網(wǎng)膜下腔出血者而CT還不能證實(shí)的診斷、減壓和引流治療。
3.出血性腦血管病與缺血性血管病的診斷和鑒別診斷,以利于擬定治療方案。
4.診斷脊髓疾病,進(jìn)行腦脊液動(dòng)力學(xué)檢測(cè),確定有無椎管內(nèi)蛛網(wǎng)膜下隙梗阻及梗阻程度,還能用于鑒別與多發(fā)神經(jīng)根病變的鑒別診斷。
5.椎管內(nèi)注射藥物。
6.開顱術(shù)后了解顱內(nèi)壓動(dòng)態(tài)變化及有無出血和感染,或者放腦脊液減壓。
7.造影檢查:如脊髓造影、氣腦造影和核素腦池掃描等。
8.中樞神經(jīng)系統(tǒng)炎癥病變、腦腫瘤、中樞神經(jīng)系統(tǒng)血管性病變、腦挫裂傷及轉(zhuǎn)移瘤的診斷和鑒別診斷。
9.某些原因不明的昏迷、抽搐等疾病的鑒別診斷。
(二)禁忌證
1.凡是有腦疝征象者(雙側(cè)瞳孔不等大、呼吸抑制、去大腦強(qiáng)直等),屬于絕對(duì)禁忌證。
2.臨床有明顯顱內(nèi)壓增高,特別是懷疑有占位性病變者,如視盤水腫、顱骨X線片或CT檢查提示顱內(nèi)占位并有顱內(nèi)壓增高,腰穿可能誘導(dǎo)腦疝發(fā)生者,且具有顱腦手術(shù)條件的情況下,確實(shí)因診斷需要,可慎重進(jìn)行。
3.腰穿穿刺部位有皮膚和軟組織感染者,腰穿易將感染帶入椎管內(nèi)甚至顱內(nèi),可行枕大池(C1~2側(cè)方)穿刺術(shù)。
4.開放性顱腦損傷或顱底骨折有腦脊液漏者,以免增加逆行感染機(jī)會(huì)。
5.穿刺部位有腰椎畸形或骨質(zhì)破壞者。
6.嚴(yán)重全身感染(敗血癥)、休克、呼吸循環(huán)衰竭、躁動(dòng)不安者,均不宜腰穿。
7.高頸段脊髓壓迫性病變、脊髓功能障礙者,腰穿易導(dǎo)致病情惡化,甚至呼吸驟停。
8.懷疑有顱后窩血腫、腫瘤者。
9.血液系統(tǒng)疾病,有出血傾向者,使用肝素等藥物抗凝或血小板<50 000/m3者。
10.未做神經(jīng)系統(tǒng)檢查,特別是未行眼底檢查者,暫不宜做腰穿。
(三)技術(shù)要領(lǐng)及方法
1.體位 穿刺成功與否,體位正確非常重要。一般采取去枕側(cè)臥位,床應(yīng)平直,軀干與床面垂直,頭部向胸前盡量俯屈,膝關(guān)節(jié)盡量向腹部屈曲,使脊柱彎成弓形,椎間隙增大到最大限度,充分暴露L3~4及L4~5間隙(雙側(cè)髂棘最高點(diǎn)連線與背正中線的交點(diǎn)相當(dāng)于L4棘突)。
2.消毒 消毒前確定好穿刺點(diǎn)。嚴(yán)格無菌操作技術(shù),腰穿包必須經(jīng)高壓消毒后再用,術(shù)者戴上無菌手套,局部用碘酊、乙醇消毒皮膚,消毒半徑為穿刺點(diǎn)周圍15cm,鋪無菌巾。
3.穿刺點(diǎn)的確定 擺好體位,先觸摸清楚穿刺的椎間隙,一般取L3~4或L4~5間隙為穿刺點(diǎn)。
4.麻醉 2%利多卡因局部浸潤麻醉(或用1%~2%普魯卡因,需要皮試),在該椎間隙正中作一皮丘,然后垂直穿刺,浸潤皮下及深部組織,注射麻醉藥物的同時(shí),還可探明椎間隙的走行方向。
5.進(jìn)針 術(shù)者左手拇指尖壓緊穿刺椎間隙一端皮膚,固定皮膚,右手持7號(hào)或9號(hào)腰穿針,于椎間隙正中垂直進(jìn)針,并稍向頭側(cè)傾斜進(jìn)行穿刺,成人進(jìn)針深度一般為5~7cm,當(dāng)針尖突破黃韌帶和硬脊膜時(shí),均有落空感,即進(jìn)入蛛網(wǎng)膜下隙,緩慢拔出針芯,可見腦脊液流出,穿刺成功;若無腦脊液流出,可適當(dāng)調(diào)整穿刺針方向和深淺。
6.測(cè)壓及放液 囑患者緩慢伸腿致半屈位,頭稍伸直,接測(cè)壓表或測(cè)壓管,然后測(cè)初壓。如果壓力高,避免誘發(fā)腦疝,不放腦脊液,將針芯拔出,將測(cè)壓管內(nèi)的腦脊液收集送腦脊液常規(guī)生化即可,若壓力不高,可緩慢釋放需要量的腦脊液,然后測(cè)末壓。收集標(biāo)本時(shí)腦脊液流速不宜過快,以每分鐘3滴為宜緩慢釋放,量一般不超過10~20ml。
7.拔針 將未污染的針芯插入,拔出穿刺針,亦可直接拔出穿刺針,穿刺點(diǎn)用碘酊消毒,無菌敷料覆蓋。
8.術(shù)畢 最好囑患者俯臥,或去枕平臥6h左右,以免腦脊液從硬脊膜穿刺孔漏入硬膜外,造成低顱壓,引起腰穿后頭痛。
(四)腰穿失敗的原因
1.穿刺方向不當(dāng)、歪斜、太淺或太深。
2.穿刺針選擇不合適,成年人用細(xì)針,患兒用粗針容易失敗。
3.病人過分緊張,亂動(dòng)可使椎間隙變小。
4.脊柱側(cè)彎畸形,病人過度肥胖。
(五)腰穿并發(fā)癥
1.腰穿后頭痛 最為常見,發(fā)生機(jī)制通常是腦脊液釋放過多,造成低顱壓,牽拉三叉神經(jīng)感覺支支配的腦膜及血管組織所致,大多出現(xiàn)在穿刺后24h,可持續(xù)5~8d,頭痛以前額和后枕部為著,跳痛或脹痛多見,還可伴頸部和后背部疼痛,咳嗽、打噴嚏或站立時(shí)癥狀加重,嚴(yán)重者還可伴有惡心、嘔吐和耳鳴。平臥時(shí)癥狀緩解,應(yīng)囑患者大量飲水,必要時(shí)可靜脈輸入生理鹽水。
2.出血 大多為損傷蛛網(wǎng)膜或硬脊膜血管所致,出血量通常很少,而且一般不引起明顯的臨床癥狀,如果出血量很多時(shí)應(yīng)與蛛網(wǎng)膜下腔出血相鑒別。
3.感染 較少見,如消毒不徹底,或者無菌操作不當(dāng),或者局部有感染灶等,可能導(dǎo)致腰穿后感染。
4.腦疝 是腰穿最危險(xiǎn)的并發(fā)癥,易發(fā)生于顱內(nèi)壓增高患者,如果顱內(nèi)壓增高患者一定要進(jìn)行腰穿才能明確診斷,一定要在腰穿前先用脫水藥或完善術(shù)前準(zhǔn)備。
(六)腦脊液壓力及動(dòng)力學(xué)檢查
1.壓力 側(cè)臥位穿刺的正常壓力成年人為80~180mmH2O,兒童為50~100mmH2O。超過200mmH2O時(shí)提示顱內(nèi)壓增高,低于80mmH2O則為低顱壓。為了解椎管是否通暢及通暢程度,常需進(jìn)一步行壓腹試驗(yàn)、壓頸試驗(yàn)。
2.壓腹試驗(yàn) 壓腹時(shí),腹腔深靜脈脊髓腔靜脈叢受壓,引起脊髓腦脊液壓力上升,去除壓力后,恢復(fù)原有水平。具體方法是:用手掌或拳頭壓迫腹部時(shí),可見腦脊液壓力迅速上升,一般約增高1倍;壓迫去除后(放手后)壓力迅速下降。15~20s恢復(fù)致正常水平。如穿刺針未在蛛網(wǎng)膜下隙,不通暢或椎管內(nèi)完全梗阻,則壓腹時(shí)壓力不升。
3.壓頸試驗(yàn)(Queckenstedt test) 當(dāng)壓迫頸靜脈時(shí),阻斷顱內(nèi)靜脈回流,引起顱內(nèi)壓驟然升高,其壓力必然通過腦脊液迅速反應(yīng)在連接的腰穿測(cè)壓管或測(cè)壓表上,正常顱壓時(shí)亦見相應(yīng)升高,解除壓迫后壓力隨之下降,借此可幫助了解腦和脊髓蛛網(wǎng)膜下隙是否通暢,顱內(nèi)靜脈竇是否阻塞。
具體操作方法:①手壓法:腰穿成功后,接測(cè)壓管或測(cè)壓表,然后助手用雙手壓迫頸靜脈10s,記錄壓力上升情況,解壓后10s,再記錄壓力下降情況。測(cè)試側(cè)竇是否梗阻,可先后壓迫一側(cè)頸靜脈,觀察上述壓力變化,并將雙側(cè)進(jìn)行比較。②頸部壓力表氣囊法:用一血壓氣囊纏于病人頸部,安上血壓表,術(shù)者腰穿完成后,測(cè)定初壓,先行壓腹試驗(yàn),確定腰穿針位于蛛網(wǎng)膜下隙,在迅速充氣至20mmHg,5s記錄上升壓力一次,直到壓力不能在上升為止,然后迅速放氣,除去壓頸,5s記錄一次壓力,直到不能下降為止,隨后在分別用同法將血壓計(jì)氣囊充氣到40mmHg及60mmHg,測(cè)定腦脊液壓力變化。以時(shí)間為橫坐標(biāo),壓力變化數(shù)值為縱坐標(biāo),描記出壓力-時(shí)間曲線。
壓頸壓力-時(shí)間曲線分析:①蛛網(wǎng)膜下隙無阻塞時(shí),腦脊液壓力在15s左右上升至最高點(diǎn),減壓后15s左右降至初壓水平,加壓至60mmHg可使顱內(nèi)壓升高至500mmH2O左右;②蛛網(wǎng)膜下隙部分阻塞時(shí),頸部加壓后腦脊液壓力上升及下降均較為緩慢,或上升迅速而下降緩慢,或減壓后壓力不能降至初壓水平;③蛛網(wǎng)膜下隙完全阻塞時(shí),頸部加壓后腦脊液壓力不上升,甚至加壓至60mmHg仍不上升;④當(dāng)一側(cè)乙狀竇血栓形成時(shí),壓迫病灶側(cè)頸靜脈,腦脊液壓力可不上升,壓迫健側(cè)頸靜脈則腦脊液壓力上升正常;⑤腰椎椎管內(nèi)腫瘤時(shí),壓腹試驗(yàn)可不上升或上升很慢,甚至為“干性”穿刺。
(七)腦脊液檢查
1.腦脊液常規(guī)
(1)性狀:正常腦脊液是無色透明的液體。當(dāng)腦脊液紅細(xì)胞數(shù)<360/m3時(shí),外觀可無明顯改變;當(dāng)紅細(xì)胞>1 000/m3時(shí)為肉眼血性腦脊液。如腦脊液為紅色或粉紅色,可用三管試驗(yàn)法予以鑒別。具體方法是:用3根試管連續(xù)接取腦脊液,前后各管為均勻一致的紅色為新鮮出血,可見于蛛網(wǎng)膜下腔出血,前后各管顏色依次變淡,為穿刺道損傷。血性腦脊液離心后顏色變?yōu)闊o色,可能為新鮮出血或穿刺道副損傷;若變?yōu)辄S色,提示為陳舊性出血;若為煙霧狀,通常是細(xì)菌感染引起的細(xì)胞數(shù)增多,見于各種化膿性腦膜炎,嚴(yán)重者可為米湯狀;放置后有纖維蛋白膜形成,見于結(jié)核性腦膜炎,該現(xiàn)象稱為蛛網(wǎng)樣凝固(cobweb-like coagulation);腦脊液呈黃色,離體后不久自動(dòng)凝固為膠凍樣,稱為弗洛因綜合征(Frion syndrome),是因?yàn)槟X脊液蛋白質(zhì)過多所致,常見于椎管梗阻。
(2)細(xì)胞數(shù):正常腦脊液細(xì)胞數(shù)為(0~5)×106/L,多為單核細(xì)胞。白細(xì)胞增多見于腦脊髓炎或腦實(shí)質(zhì)炎性病變,涂片檢查如發(fā)現(xiàn)致病菌(細(xì)菌、真菌)及脫落的瘤細(xì)胞等,有助于病因診斷。
(3)潘氏試驗(yàn)(Pandy test):是一種腦脊液蛋白定性試驗(yàn)方法。利用腦脊液中球蛋白能和飽和石炭酸結(jié)合形成不溶性蛋白鹽的原理,球蛋白含量越高反應(yīng)反而越明顯,通常作為蛋白定性的參考試驗(yàn),可出現(xiàn)假陽性反應(yīng)。
2.腦脊液生化檢查
(1)蛋白:正常人(腰穿)腦脊液蛋白含量為0.15~0.45g/L,腦池液位0.1~0.25g/L,腦室液為0.05~0.15g/L,蛋白質(zhì)增高見于中樞神經(jīng)系統(tǒng)感染、腦腫瘤、腦出血、脊髓壓迫癥、吉蘭-巴雷綜合征、糖尿病性神經(jīng)根神經(jīng)病、黏液性水腫及全身感染等;蛋白降低見于腰穿或硬膜損傷腦脊液丟失,身體極度虛弱和營養(yǎng)不良者。
(2)糖:腦脊液糖含量取決于血糖水平,正常值為2.5~4.4mmol/L,為血糖的50%~70%。通常腦脊液糖低于2.25mmol/L為異常,見于化膿性腦膜炎,輕至中度減少見于結(jié)核性或真菌性腦膜炎(特別是隱球菌性腦膜炎)以及腦膜癌病;糖含量增高見于糖尿病。
(3)氯化物:正常腦脊液含氯化物120~130mmol/L,較血氯水平高,細(xì)菌性或真菌性腦膜炎均可使氯化物含量降低,尤其以結(jié)核性腦膜炎最為明顯,氯化物降低還可見于全身性疾病引起的電解質(zhì)紊亂等。
3.特殊檢查 其他較為特殊的檢查包括細(xì)胞學(xué)檢查、蛋白電泳、免疫球蛋白、寡克隆區(qū)帶、酶、病毒學(xué)檢測(cè)、囊蟲特異性抗體檢測(cè)、抗酸染色、墨汁染色、細(xì)菌及真菌培養(yǎng)等,外傷合并顱內(nèi)感染,抗酸染色、墨汁染色、細(xì)菌及真菌培養(yǎng)往往是常用的腦脊液檢查,明確感染原因,以利于對(duì)癥下藥。
(吳國材 李明榮 楊 慧 陳 鵬 張世彬 張 弦 高伯元 張禮均)
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