鐘卓霖 胡建華

（1.浙江大學(xué)醫(yī)學(xué)院附屬第四醫(yī)院骨科，浙江 義烏322000；2.中國醫(yī)學(xué)科學(xué)院北京協(xié)和醫(yī)學(xué)院北京協(xié)和醫(yī)院骨科，北京 100730）

頸椎后縱韌帶骨化（ossification of the posterior longitudinal ligament,OPLL）于1838年被首次介紹[1],直至19世紀(jì)60年代由Tsukimoto[2]研究報(bào)道后才被廣泛認(rèn)可。OPLL是骨在后縱韌帶中異化形成的一種病理狀態(tài)，其可以逐步導(dǎo)致脊髓受壓，是導(dǎo)致患者發(fā)生頸椎脊髓病變的常見原因，文獻(xiàn)報(bào)道頸椎OPLL的發(fā)病率為1.9%～4.3%[3,4]。日本學(xué)者根據(jù)頸椎平片上OPLL形態(tài)學(xué)特點(diǎn)將其分成4種類型：節(jié)段型、連續(xù)型、混合型以及局灶型[5]。治療上，頸椎OPLL的治療包括保守治療及手術(shù)治療，前者包括密切隨訪、物理治療及口服止痛藥物等；后者包括前路減壓融合術(shù)、后路單開門成形術(shù)以及后路椎板切除術(shù)等。

臨床上，對(duì)于無癥狀的頸椎OPLL患者，并不提倡手術(shù)治療，手術(shù)只適用于已經(jīng)發(fā)生脊髓病變的患者，其方式通常包括前路手術(shù)及后路手術(shù)。頸椎OPLL患者術(shù)后療效及并發(fā)癥發(fā)生率不盡相同，本文即對(duì)頸椎OPLL手術(shù)治療的預(yù)后相關(guān)因素做簡要闡述。

1 K線

K線，于2008年被首次提出，是指頸椎側(cè)位平片上C2至C7椎管中點(diǎn)的連線，它同時(shí)反映出頸椎曲度與后縱韌帶骨化厚度兩個(gè)參數(shù)；OPLL未越過K線時(shí)稱為K線（+），反之為K線（-）[6]。Fujiyoshi等[6]報(bào)道，在接受頸后路減壓術(shù)后，K線（-）組患者的治愈率為13.9%，而K線（+）組的為66.1%，后者的預(yù)后明顯優(yōu)于前者，其原因是K線（-）組患者術(shù)后脊髓不能完全漂移以獲得充分減壓。Koda等[7]研究報(bào)道，對(duì)于K線（-）OPLL患者而言，相對(duì)于頸后路，頸前路減壓融合術(shù)更適合。Takeuchi等[8]對(duì)K線的臨床意義進(jìn)行進(jìn)一步研究，發(fā)現(xiàn)術(shù)后K線（-）組患者的治愈率明顯低于K線（+）組（前者為23.8%，后者為46.3%）。

2 OPLL的椎管占有率

OPLL的椎管占有率是指后縱韌帶骨化的最大厚度與相應(yīng)水平椎管直徑的比值。Kato等[9]報(bào)道了一項(xiàng)關(guān)于545例頸椎OPLL患者行椎板成形術(shù)的多中心研究結(jié)果，發(fā)現(xiàn)OPLL患者椎板成形術(shù)后發(fā)生嚴(yán)重并發(fā)癥的一個(gè)重要因素是術(shù)中失血量，而對(duì)于椎管占有率＞60%的患者其術(shù)中失血量明顯升高，可能由骨化組織壓迫硬膜外椎靜脈叢，使靜脈壓力增加，從而導(dǎo)致術(shù)中靜脈出血增加引起。多數(shù)學(xué)者[10-12]認(rèn)為，當(dāng)椎管占有率＞50%，尤其是＞60%時(shí)，接受頸后路椎板成形術(shù)的患者預(yù)后較差。

3 頸椎曲度

Ogawa等[13]報(bào)道，術(shù)前頸椎曲度后凸OPLL患者在接受頸后路椎板成形術(shù)治療后預(yù)后較差，原因是頸后路椎板成形術(shù)對(duì)于此類患者不能實(shí)現(xiàn)充分減壓。Yoshii等[14]報(bào)道，對(duì)于椎管占有率＞50%的頸椎OPLL患者，前路減壓融合術(shù)與后路減壓融合術(shù)在術(shù)后治愈率上無顯著差異，但對(duì)于合并頸椎后凸的此類患者，在神經(jīng)功能改善程度上，前者會(huì)比后者更勝一籌。

4 硬膜骨化

硬膜骨化于1997年首次被提出[15]，其被認(rèn)為是頸椎OPLL的一種重要影像學(xué)征象，對(duì)手術(shù)方式的選擇及術(shù)后患者的預(yù)后具有重大影響。當(dāng)硬膜骨化時(shí)，頸前路術(shù)中分離后縱韌帶和硬膜時(shí)將會(huì)變得非常困難，術(shù)中更容易發(fā)生硬膜外出血及腦脊液漏[16,17]。對(duì)于合并硬膜骨化的OPLL患者，選擇前路減壓融合術(shù)術(shù)后發(fā)生腦脊液漏的概率高，雖然大多數(shù)發(fā)生腦脊液漏的患者經(jīng)過保守治療后能痊愈，但這仍會(huì)顯著延長患者住院時(shí)間且會(huì)增加感染的風(fēng)險(xiǎn)[16,18]。此外，腦脊液漏也可能繼發(fā)腦膜炎、傷口延遲愈合、氣管堵塞以及假性腦膜膨出等并發(fā)癥[19]。

5 后縱韌帶骨化形態(tài)

依據(jù)頸椎側(cè)位片上后縱韌帶骨化的形態(tài)，可以把OPLL分為平坦型和山丘型，對(duì)于平坦型的OPLL患者而言，頸后路椎板成形術(shù)是一種有效而又安全的手術(shù)方式；而對(duì)于山丘型的OPLL患者而言，椎板成形術(shù)的治療效果較差，其原因是山丘型的后縱韌帶骨化在局部銳性擠壓脊髓，影響脊髓功能，在日本骨科協(xié)會(huì)（Japanese Orthopedic Association,JOA）評(píng)分上，山丘型明顯低于平坦型[19,20]。

6 脊髓信號(hào)改變

頸椎OPLL患者手術(shù)預(yù)后與術(shù)前頸椎核磁（magnetic resonance,MR）圖像上脊髓信號(hào)的改變也有密切關(guān)系，這與既往脊髓型頸椎病合并脊髓信號(hào)改變與手術(shù)預(yù)后關(guān)系的研究結(jié)果相似[21,22]。Ito等[22]根據(jù)MR T2序列上脊髓信號(hào)的特點(diǎn)將脊髓變性分為3級(jí)：1級(jí)，輕度，信號(hào)沒有任何改變；2級(jí)，中度，信號(hào)模糊改變；3級(jí)，重度，信號(hào)明顯改變。隨訪119例患者后發(fā)現(xiàn)，術(shù)前脊髓信號(hào)改變與手術(shù)的預(yù)后密切相關(guān)，脊髓信號(hào)級(jí)別越高，預(yù)后越差[22]。也有研究[23]報(bào)道，術(shù)前頸椎MR T1序列圖像上信號(hào)降低也是術(shù)后預(yù)后較差的因素之一。

7 合并外傷

OPLL合并脊髓損傷（spinal cord injury,SCI）在臨床中也常見，文獻(xiàn)[24,25]報(bào)道在SCI患者中，合并OPLL的發(fā)生率達(dá)38%。Soon等[26]報(bào)道，OPLL合并SCI的患者手術(shù)預(yù)后與術(shù)前MR T2圖像上脊髓信號(hào)改變、脊髓受壓的嚴(yán)重程度及患者神經(jīng)功能狀態(tài)密切相關(guān)；術(shù)前MR T2像上脊髓信號(hào)改變?cè)矫黠@，脊髓受壓越嚴(yán)重，或術(shù)前神經(jīng)功能越差，患者的預(yù)后越差。

8 手術(shù)方式

手術(shù)是有癥狀的頸椎OPLL患者的主要治療方式，主要包括頸前路手術(shù)、頸后路手術(shù)以及后前路聯(lián)合手術(shù)。前路減壓手術(shù)能獲得更好的減壓效果，尤其對(duì)于脊髓明顯受壓的患者，但是對(duì)于某些此類患者而言，脊髓受壓越嚴(yán)重也就意味著在行前路手術(shù)時(shí)脊髓受損害的風(fēng)險(xiǎn)越高，術(shù)后預(yù)后反而較差[19]。前路手術(shù)主要包括椎體次全切除合并融合術(shù)、椎間盤切除合并融合術(shù)，以及漂浮減壓術(shù)；后路手術(shù)是間接減壓，手術(shù)技術(shù)上比較容易達(dá)到，該術(shù)式主要包含椎板成形術(shù)、椎板切除術(shù)及椎板切除合并融合術(shù)；也有學(xué)者建議對(duì)于少數(shù)頸椎OPLL患者可以選擇后前路聯(lián)合手術(shù)[14,27-29]。選擇不同的手術(shù)方式，患者的預(yù)后會(huì)有不同。技術(shù)上，因前路手術(shù)是直接減壓神經(jīng)，術(shù)中容易發(fā)生脊髓損傷和腦脊液漏，尤其對(duì)于合并硬膜骨化的患者，且相比較而言，頸前路通常需要更長的手術(shù)時(shí)間；而后路手術(shù)是間接減壓，相對(duì)而言發(fā)生脊髓神經(jīng)損傷的風(fēng)險(xiǎn)較小，但是術(shù)中容易出血，尤其是當(dāng)椎管占有率＞60%時(shí)，術(shù)中出血明顯增加，術(shù)后并發(fā)癥風(fēng)險(xiǎn)顯著上升[9,10,14,19]。Kim等[11]報(bào)道，對(duì)于OPLL椎管占有率≥60%或MR提示脊髓信號(hào)改變的頸椎OPLL患者，頸椎前路減壓融合術(shù)的手術(shù)治療效果要優(yōu)于頸后路椎板成形術(shù)。Liu等[30]比較頸后路椎板擴(kuò)大成形術(shù)與椎板切除內(nèi)固定融合術(shù)治療頸椎曲度偏直（C2-7的Cobb角介于0°～10°）的OPLL患者的治療效果，結(jié)果表明，相對(duì)于頸后路椎板切除內(nèi)固定融合術(shù)，頸后路椎板擴(kuò)大成形術(shù)在術(shù)后神經(jīng)功能恢復(fù)及頸部功能改善方面更具優(yōu)勢(shì)，疼痛評(píng)分及術(shù)后軸性疼痛也較低。鑒于前后路手術(shù)各自的優(yōu)缺點(diǎn)，有學(xué)者提出后前路聯(lián)合治療復(fù)雜的頸椎OPLL患者。Lee等[27]提出540°頸椎組合術(shù)式治療頸椎廣泛OPLL伴頸椎后突患者，該術(shù)式一期行后路椎板切除及小關(guān)節(jié)松解+螺釘固定術(shù)，二期行前路椎間盤切除融合+后路內(nèi)固定融合術(shù)，術(shù)后JOA評(píng)分由術(shù)前8.2分提高到14.8分，OPLL椎管占有率從73.5%降到38.4%。此外，薈萃分析[4]報(bào)道，行頸后路單開門減壓的頸椎OPLL患者，OPLL影像學(xué)上進(jìn)展率明顯高于頸椎減壓融合術(shù)組（前者為62.5%，后者為7.6%）。

9 其他

此外，頸椎OPLL手術(shù)治療的預(yù)后與患者年齡也密切相關(guān)，年齡越大，預(yù)后差的可能性越大，其原因是滋養(yǎng)脊髓的血管在老年患者中易發(fā)生動(dòng)脈粥樣硬化，這使脊髓在應(yīng)激條件下容易發(fā)生缺血，不利于術(shù)后脊髓神經(jīng)功能的恢復(fù)[26]；術(shù)前患者癥狀持續(xù)時(shí)間長、合并糖尿病史、JOA評(píng)分低都是患者術(shù)后恢復(fù)較差的預(yù)測因素[23,31,32]。

盡管頸椎OPLL已被臨床醫(yī)師所熟知，但目前仍有較多問題需要進(jìn)一步研究。手術(shù)是頸椎OPLL患者的主要治療方式，如何根據(jù)患者不同的臨床特點(diǎn)及不同的影像學(xué)特征選擇合適的手術(shù)方式需要每一位脊柱外科醫(yī)師思考，在以后的臨床治療中，需要更多的長期隨訪研究為臨床決策提供參考依據(jù)。

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