Abstract
目的
总结成人先天性皮窦道(dermal sinus tract, DST)合并脊髓拴系综合征(tethered cord syndrome, TCS)的临床特点、影像学特征及手术治疗经验。
方法
回顾性分析2010年9月至2019年10月经手术治疗的25例成人先天性DST合并TCS患者的临床资料。本组男10例，女15例，年龄18~48岁，平均年龄29.7岁。25例在腰骶部中线附近见皮窦口，周围皮肤变性，临床上以腰腿痛、双下肢麻木无力、大小便功能障碍为主要症状，2例以急性脑脊液漏合并脑膜炎急诊入院。根据术前磁共振(magnetic resonance imaging, MRI)影像了解DST在硬膜下走行、脊髓圆锥位置、硬膜下有无病变、内终丝直径等，显微镜下行DST分离并切除、内终丝切断、TCS松解、脊膜囊重建术，术后患者俯卧位7 d。
结果
MRI显示，25例患者脊髓圆锥位置均低于腰2椎体水平，DST远端进入硬膜下构成脊髓牵张因素之一，24例患者见内终丝脂肪浸润增粗，另1例患者终丝增粗直径5 mm牵张脊髓圆锥。手术将DST的异常皮肤、皮下瘘管及硬膜下索条全切除，将增粗终丝离断，松解TCS，2例患者合并硬膜下皮样囊肿，予以分离切除。手术后病理符合皮窦道和终丝结构，患者术后疼痛缓解或消失，双下肢无力及大小便功能障碍逐渐恢复，无手术并发症。随访3个月至9年，平均3.9年，所有患者神经功能完好，复查MRI显示胸腰椎生理曲度完好，随访期间未见TCS复发。
结论
先天性DST合并的成人型TCS均合并内终丝增粗牵张，手术在显微镜下行皮窦道全程分离切除、终丝离断、TCS松解及硬膜重建，手术预后较好。
Keywords: 脊髓拴系综合征, 皮窦道, 内终丝, 显微外科手术
Abstract
Objective
To summarize the clinical manifestations, imaging characteristics and experience of surgical treatment of tethered cord syndrome (TCS) accompanied by dermal sinus tract (DST) in adulthoods.
Methods
The authors retrospectively analyzed a series of 25 adult patients with TCS due to DST that were surgically treated under microscope from September 2010 to October 2019. There were 10 males and 15 females with an average age of 29.7 years (rang, 18-48 years). Characterized cutaneous malformation and dermal sinus were found in the lumbosacral region in all the 25 patients. Clinically, all the patients presented with chronic back and lower-extremity pain, numbness and weakness of lower limbs, and bowel and bladder dysfunction. Two cases were admitted to the emergency room with acute infectious cerebral spinal fluid (CSF) leakage complicated with meningitis. According to magnetic resonance imaging (MRI) images, the subdural course of DST whose traction of the spinal cord, the location of the conus medullaris, the presence of subdural lesions, and the diameter of the internal filum terminale were evaluated. The surgical procedure included separating and excising of the DST, section of the internal filum terminale, detethering of the TCS, and reconstruction of the dural sac under microscopy. The patients remained in prone position in 7 days postoperation.
Results
MRI showed that the position of the conus medullaris was lower than the level of lumbar 2 vertebrae, and the distal part of the DST entered the subdural stretched part of the spinal cord, to constitute one of the factors of TCS in all the 25 patients. Twenty patients had fatty infiltration of internal filum terminale and another patient had thickened (approximately 5 mm in diameter) internal filum terminale resulting in tightening the conus medullaris. A total of 25 operations were performed including completely dissection and resection of the DST through the skin down to the subdural space, section of the internal filum terminale, detethering of the TCS, and the subdural dermoid cysts were removed in two patients. There were no postoperative complications. The postoperative pathology was consistent with the structure of the DST and internal filum terminale. The local pain was relieved, and the lower-extremity weakness and bowel and bladder dysfunction were gradually relieved postoperatively. The period of follow-up ranged from 3 months to 9 years (mean, 3.9 years). The neurological function of all the patients was intact, and MRI showed that the physiological curvature of the thoracolumbar spine remained normal. There was no recurrence of TCS observed during the follow-up.
Conclusion
The adult TCS accompanied with DST is characterized by typical cutaneous malformation in the lumbosacral region and tethering of the spinal cord. The patients are usually combined with internal filum terminale enlargement tightening of conus medullaris as well. The surgical treatment including totally resection of the DST and section of the internal filum terminale to detethering the TCS at the same time under microscopy. The outcome of surgical treatment is satisfactory.
Keywords: Tethered cord syndrome, Dermal sinus tract, Filum terminale, Microsurgery
先天性皮窦道(dermal sinus tract, DST)是开口于躯体背侧中线皮肤的外胚层管道，其深度可以是皮下至硬膜下任何一点。普遍认为DST是神经管缺陷(neural tube defect, NTD)的一种，源于胚胎期神经外胚层与皮肤外胚层分离失败所致，主要发生在神经轴的背侧，以腰骶部多见[1-2]。DST发病率为1/2 500，于新生儿或婴幼儿期发现局部皮肤异常，其中50%以上皮下瘘管穿过硬脊膜，皮下瘘道盲端还会并发皮样或表皮样囊肿，严重者并发细菌性脑膜炎等急症[3]。DST可引起脊髓拴系综合征(tethered cord syndrome, TCS)，需要早期手术治疗[4-5]。
成人DST型TCS多见个案报道，本研究收集2010年9月至2019年10月间收治的25例患者，就其临床及影像学表现、手术方法及疗效等进行总结。
1. 资料与方法
1.1. 一般资料
2010年9月至2019年10月，北京大学第三医院神经外科收治的25例DST型TCS患者，纳入标准：(1)以DST为主要原因的TCS成人患者；(2)临床资料完整且获得3个月以上随访者。排除标准：(1)由于其他畸形为主导致的TCS，如脊髓纵裂、脂肪脊髓脊膜膨出或脊髓脊膜膨出；(2)儿童患者。本组25例，其中男10例，女15例，年龄18~48岁，平均年龄29.7岁，病程2 d至17年。
1.2. 临床表现
以慢性腰腿痛为主19例，以下肢肌力下降为主、继发肌萎缩、发生马蹄内翻足或高弓足6例，其中下肢无力合并腰腿痛5例。25例中伴大小便障碍8例。查体见腰骶部皮肤异常开口，周围见变性的皮肤呈橘皮样，伴有异常毛发、色素沉着、血管瘤、异常凹陷或隆起(图 1)。2例因高热、寒战、头痛、呕吐等中枢神经系统感染急诊入院。既往史中，6例有瘘口间断性渗液及发热头痛病史。术前神经功能Hoffman分级[6], 0级4例，1级11例，2级10例。
图 1.
先天性皮窦道表面瘘口(箭头所示)及周围皮肤色素沉着
Fistula of the dermal sinus tract (arrow) and pigmentation of the surrounding skin
1.3. 术前磁共振成像
磁共振成像(magnetic resonance imaging, MRI)显示皮下瘘道管走行，位于腰背部10例，位于腰骶结合处10例，位于骶部5例(图 2)。MRI均显示脊髓圆锥下降至第二腰椎以下水平，24例可见脂肪浸润增粗的内终丝，另外1例见内终丝增粗直径约5 mm，牵张脊髓圆锥。合并硬膜下囊肿2例。
图 2.
不同部位DST型TCS术前MRI
Preoperative MRI of DST accompanied with TCS on different level
A, lumbar MRI enhanced sagittal scan showed lumbar 2-3 segmental cutaneous sinus and subcutaneous fistula, which entered the subdural area and pulled the spinal cord; B, sagittal T2-weighted MRI of lumbosacral, showing cutaneous sinus and subcutaneous fistula to subdural at lumbar 5-sacral 1 level, with congenital tumors of the spinal cord; C, sagittal T2-weighted MRI of lumbosacral, showing cutaneous sinus and subcutaneous fistula at the level of sacral 2-3, with fistula entering the subdural space. DST, dermal sinus tract; TCS, tethered cord syndrome; MRI, magnetic resonance imaging.
1.4. 手术方法
手术在气管插管全身麻醉下进行，患者采取俯卧位，腰骶部处于最高位，设计以皮窦道口及周围变性组织为中心的横行或纵行梭状切口线，术中神经电生理监测，(1)逐层切开皮肤、皮下组织，至筋膜层，沿途完整分离皮下瘘道，平筋膜层夹闭并横断瘘道；(2)沿瘘道走行，行骨膜下剥离椎旁肌显露至瘘道进入脊柱裂处，扩大咬除此处异常的棘突及椎板，显露硬膜层；(3)显微镜下剪开硬脊膜，向两侧悬吊显露硬膜下腔，沿硬膜下部分追索瘘道，彻底切除DST(图 3)；(4)常规进行终丝探查及切断术，利用同一切口或附加切口行内终丝分离切除；(5)向头端松解蛛网膜及马尾神经粘连，直到马尾神经松弛于椎管内腹侧，将蛛网膜覆盖其表面，将硬膜严密缝合，重建完整的硬膜囊。
图 3.
第五腰椎至第一骶椎水平DST型TCS
DST accompanied with TCS at the lumbar 5-sacral 1 level
A, sagittal CT of the lumbar spine, showing spina bifida of lumbar 5-sacral 1, with cutaneous sinus and subcutaneous fistula shadow; B, sagittal T2-weighted MRI of lumbosacral vertebrae, showing cutaneous sinus and subcutaneous fistula at lumbar 5-sacral 1 level to subdural level, combined with low conus spinal cord; C, intraoperative imaging showing the fistula entering the subdural space and moving towards the head to stretch the spinal cord(arrow). DST, dermal sinus tract; TCS, tethered cord syndrome; CT, computerized tomography; MRI, magnetic resonance imaging.
1.5. 术后观察及随访
按照Kirollos等[7]的TCS松解评分评价手术松解程度。术后患者取俯卧位7 d，切口区域予以沙袋压迫。术后3周开始腰背肌功能康复训练。根据症状、体征记录评价患者出院时的治疗效果分为好转、不变及恶化，具体指标包括，以视觉模拟疼痛评分(visual analogue scale VAS)评价疼痛改变，采用关键肌肉力量0~5级评分评价下肢运动功能，用日本骨科协会(Japanese orthopeadic association, JOA)括约肌功能评分[8]评价膀胱功能，即，0分，尿闭或尿失禁；1分，排尿不尽感，排尿费力，排尿时延长，尿痛；2分，排尿延迟，尿频；3分，正常。采用Hoffman分级标准[6]评价患者脊髓功能状态。随访时以MRI及腰椎正、侧屈伸位X线片结果评价脊髓形态及脊柱稳定性。
1.6. 统计学分析
经Kolmogorov-Smirnov检验，所有数据均符合正态分布。VAS评分结果、下肢关键肌肉力量、JOA括约肌评分以均数±标准差表示。以方差及t检验进行统计学分析，P < 0.05为差异有统计学意义。
2. 结果
2.1. 手术情况
手术时间1.2~3.6 h，平均1.7 h；出血量50~350 mL，平均165 mL。25例均将DST全程切除，按Kirollos标准行TCS Ⅰ级松解术，术后组织学检查显示：DST瘘管内衬鳞状上皮，上皮细胞内含有纤维、脂肪组织，可见少量神经胶质细胞；内终丝可见脂肪组织及纤维结缔组织浸润增粗；2例硬膜下肿瘤符合皮样囊肿。无手术相关并发症发生。
2.2. 近期临床疗效
(1) 术前疼痛19例患者手术后疼痛缓解或消失，VAS评分从术前的(6.37 ± 3.50)分降到术后的(2.10 ± 3.72)分，差异有统计学意义(P < 0.05)；(2)6例运动障碍者手术后肌力提高1~2级；(3)8例括约肌功能障碍者，JOA括约肌评分从(1.76±1.90)分上升到(2.77±1.23)分，术后近期运动及括约肌障碍差异无统计学意义(P＞0.05)。
2.3. 随访情况
随访3个月至9年，平均3.9年。随访期间，脊髓功能状态按Hoffman分级标准，0级9例，1级11例，2级5例；改善7例，稳定18例。与术前相比差异有统计学意义(P < 0.05)，末次随访期间行MRI检查证实脊髓圆锥及马尾神经松弛，脊柱序列及曲度完好。
3. 讨论
TCS是由于非弹力结构牵张脊髓末端导致的神经障碍症候群，其常见病因为神经管缺陷类疾病，如脊髓纵裂、脂肪脊髓脊膜膨出、脊髓脊膜膨出、终丝增粗牵张、DST等[9]。
DST包括位于背部皮肤中线及附近的异常皮肤开口、皮下瘘管、盲端病变，主要发生于神经轴背侧，从枕部到腰骶尾部的任何部位均可发生，以腰骶部多见，50%以上的DST可通过脊柱裂进入椎管内，并穿透硬脊膜进入蛛网膜下腔[2-5]，从而牵张脊髓导致临床上TCS[10-12]。另外，由于DST与蛛网膜下沟通，继发脑脊液漏，导致逆行中枢神经系统感染，属于神经外科急症[3-5]。皮下瘘道盲端还可继发椎管内硬膜下皮样及表皮样囊肿[12]，导致脊髓及神经根压迫及刺激症状。由于胚胎发育因素，导致皮毛窦与瘘道远端硬膜下部分不一定处于同一水平，可能相差1~3个椎体节段。MRI检查可以在术前明确窦道是否进入椎管内，是否合并椎管内先天性肿瘤，从而指导手术方案，但这不是绝对的，通过实践总结，学者提出应该对DST进行全程解剖分离和硬膜下探查[13]。
鉴于DST在其他类型TCS中亦会合并发生，本研究收集了近9年来，以DST为主要因素的成人TCS患者25例，所纳入的病例中DST均位于腰骶部，其皮下瘘道管位于腰背部10例，位于腰骶结合处10例，位于骶部5例，临床特点分为三部分：(1)DST症状及体征，成年人DST发病者，因病程长，皮下组织反复刺激或继发感染，导致局部皮肤变性影响外观，表现为腰骶部背侧中线或中线旁异常皮肤窦口呈火山口样凹陷或增生，周围伴色素沉着、毛发增生、毛细血管瘤等，本组既往有反复脑脊液漏及感染发作6例；(2)继发的TCS特点，以慢性腰腿痛为主19例，以下肢肌力下降为主、继发肌萎缩、发生马蹄内翻足或高弓足6例，其中下肢无力合并腰腿痛5例，25例中伴大小便障碍8例；(3)合并感染及肿瘤，继发中枢神经系统感染起病急骤，伴有颈项强直等急诊入院2例，6例既往曾经有局部脑脊液漏发热头痛病史，继发椎管内肿瘤出现脊髓压迫症状及体征2例，都属于神经外科急症。
基于胚胎发生学及既往经验总结[14]，笔者推测DST型TCS其终丝增粗牵张脊髓圆锥会成为重要附加因素。本组25例中，术前X线片及CT检查可显示脊柱裂部位，MRI检查能显示皮窦道全程，皮下瘘管呈长T1、长T2类似脑脊液信号，其硬膜下部分经蛛网膜下腔终止于脊髓、神经根，从而造成脊髓牵拉。本组25例患者，24例术前MRI显示内终丝因脂肪浸润增粗，另外1例内终丝明显增粗至5 mm，从尾端牵张脊髓圆锥, 也印证了术前推断。
伴有DST的成人TCS应尽早手术治疗，手术目的是全程解剖及切除DST、松解脊髓栓系、重建硬膜囊。在临床实践中，我们总结该类手术的操作要点包括：(1)皮肤至筋膜层操作过程中，注意保持皮下瘘道完整，防止污染，将皮窦及变性皮肤皮下组织切除；(2)以瘘道进入椎管部位为中心，行椎板切除显露硬膜层，显微镜下沿硬膜下部分追索至蛛网膜下腔，进一步向瘘管盲端分离，彻底切除病灶；(3)利用同一切口或附加切口行内终丝分离切断术，终丝切断才能完全松解TCS，向头端松解蛛网膜及粘连的马尾神经，直到马尾神经松弛于椎管内腹侧，将蛛网膜覆盖其表面，将硬膜严密缝合，重建完整的硬膜囊；(4)为了避免手术对脊髓及马尾神经的损伤，有效的术中监护特别重要[15]；(5)术后嘱患者俯卧5~7 d，保证切口愈合，以及脊髓末端升高。
本组25例DST型TCS成人患者，采取及时正确的手术，近期临床疗效满意，疼痛症状得到不同程度缓解，虽然在术后早期，下肢肌力提高及膀胱括约肌功能改善较慢，在平均3.9年的随访中，神经功能恢复良好，无再发生TCS的病例。MRI检查显示脊髓及马尾神经形态学恢复良好，脊柱的生理曲度被完好保留。
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