頸椎后縱韌帶骨化手術(shù)治療預后相關(guān)因素分析

鐘卓霖 胡建華

（1.浙江大學醫(yī)學院附屬第四醫(yī)院骨科，浙江 義烏322000；2.中國醫(yī)學科學院北京協(xié)和醫(yī)學院北京協(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60年代由Tsukimoto[2]研究報道后才被廣泛認可。OPLL是骨在后縱韌帶中異化形成的一種病理狀態(tài)，其可以逐步導致脊髓受壓，是導致患者發(fā)生頸椎脊髓病變的常見原因，文獻報道頸椎OPLL的發(fā)病率為1.9%～4.3%[3,4]。日本學者根據(jù)頸椎平片上OPLL形態(tài)學特點將其分成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，本文即對頸椎OPLL手術(shù)治療的預后相關(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椎管中點的連線，它同時反映出頸椎曲度與后縱韌帶骨化厚度兩個參數(shù)；OPLL未越過K線時稱為K線（+），反之為K線（-）[6]。Fujiyoshi等[6]報道，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]研究報道，對于K線（-）OPLL患者而言，相對于頸后路，頸前路減壓融合術(shù)更適合。Takeuchi等[8]對K線的臨床意義進行進一步研究，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水平椎管直徑的比值。Kato等[9]報道了一項關(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)生嚴重并發(fā)癥的一個重要因素是術(shù)中失血量，而對于椎管占有率＞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，從而導致術(shù)中靜脈出血增加引起。多數(shù)學者[10-12]認為，當椎管占有率＞50%，尤其是＞60%時，接受頸后路椎板成形術(shù)的患者預后較差。

3 頸椎曲度

Ogawa等[13]報道，術(shù)前頸椎曲度后凸OPLL患者在接受頸后路椎板成形術(shù)治療后預后較差，原因是頸后路椎板成形術(shù)對于此類患者不能實現(xiàn)充分減壓。Yoshii等[14]報道，對于椎管占有率＞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]，其被認為是頸椎OPLL的一種重要影像學征象，對手術(shù)方式的選擇及術(shù)后患者的預后具有重大影響。當硬膜骨化時，頸前路術(shù)中分離后縱韌帶和硬膜時將會變得非常困難，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，但這仍會顯著延長患者住院時間且會增加感染的風險[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（Japanese Orthopedic Association,JOA）評分上，山丘型明顯低于平坦型[19,20]。

6 脊髓信號改變

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

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[24,25]報道在SCI患者中，合并OPLL的發(fā)生率達38%。Soon等[26]報道，OPLL合并SCI的患者手術(shù)預后與術(shù)前MR T2圖像上脊髓信號改變、脊髓受壓的嚴重程度及患者神經(jīng)功能狀態(tài)密切相關(guān)；術(shù)前MR T2像上脊髓信號改變越明顯，脊髓受壓越嚴重，或術(shù)前神經(jīng)功能越差，患者的預后越差。

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，尤其對于脊髓明顯受壓的患者，但是對于某些此類患者而言，脊髓受壓越嚴重也就意味著在行前路手術(shù)時脊髓受損害的風險越高，術(shù)后預后反而較差[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)；也有學者建議對于少數(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，患者的預后會有不同。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)時間；而后路手術(shù)是間接減壓，相對而言發(fā)生脊髓神經(jīng)損傷的風險較小，但是術(shù)中容易出血，尤其是當椎管占有率＞60%時，術(shù)中出血明顯增加，術(shù)后并發(fā)癥風險顯著上升[9,10,14,19]。Kim等[11]報道，對于OPLL椎管占有率≥60%或MR提示脊髓信號改變的頸椎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，相對于頸后路椎板切除內(nèi)固定融合術(shù)，頸后路椎板擴大成形術(shù)在術(shù)后神經(jīng)功能恢復及頸部功能改善方面更具優(yōu)勢，疼痛評分及術(shù)后軸性疼痛也較低。鑒于前后路手術(shù)各自的優(yōu)缺點，有學者提出后前路聯(lián)合治療復雜的頸椎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]報道，行頸后路單開門減壓的頸椎OPLL患者，OPLL影像學上進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)治療的預后與患者年齡也密切相關(guān)，年齡越大，預后差的可能性越大，其原因是滋養(yǎng)脊髓的血管在老年患者中易發(fā)生動脈粥樣硬化，這使脊髓在應激條件下容易發(fā)生缺血，不利于術(shù)后脊髓神經(jīng)功能的恢復[26]；術(shù)前患者癥狀持續(xù)時間長、合并糖尿病史、JOA評分低都是患者術(shù)后恢復較差的預測因素[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及不同的影像學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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