Lumbar spinal stenosis. Radiographic diagnosis with special reference to transverse axial tomography.

Spinal stenosis due to malalignment and/or hypertrophy of the bony margins of the spinal canal is a recognized cause of cauda equina compression and nerve root entrapment. The plain lumbosacral spine roentgenograms reveal the number of lumbar vertebrae, their alignment, their interpedicular distances, the height of the intervertebral disk spaces and the presence of osteophyte formation. It correlates poorly with encroachment on the spinal canal. The transverse axial tomogram directly demonstrates a cross-section of the spinal canal and will show abnormal areas of bone encroachment usually arising from hypertrophied lamina and articular processes. These narrow the posterior portion of the spinal canal and encroach on the lateral recesses. This examination does not demonstrate soft tissue hypertrophy and the stenosis may be even greater than what is apparent due to the bony encroachment. The myelogram expresses how the narrowed spinal canal affects the dural sac and its contained cauda equina. Not infrequently there is an associated herniated disk.     

Extended posture of lumbar spine precipitating cauda equina compression arising from a postoperative epidural clot

We report a patient with nonoperatively treated acute cauda equina compression arising from an epidural clot that developed after decompressive surgery for lumbar canal stenosis. A 43-year-old woman underwent lumbar laminotomy, and was symptom-free for 3 hours; but this was followed by paresis. Postoperative myelography showed obstruction of the contrast column at the level of the laminotomy; this was relieved by hyperflexion of the lumbar spine. With sustained hyperflexion of the lumbar spine, all neurologic deficits were completely resolved within 5 days. Lumbar lordosis may be present when a patient lies in the supine position on a flat bed with the hips and knees extended; this may exacerbate dural constriction caused by an epidural clot following posterior lumbar spinal surgery. Received: February 23, 2000 / Accepted: August 15, 2000     

The effect of flexion on the level of termination of the dural sac in paediatric patients

Although the anatomy of the spinal cord and its associated structures have been well defined, the effects of body position relevant to neuraxial blockade have not been elucidated. This study was designed to determine the effect of body position on the end of the dural sac in children. After induction of anaesthesia, ultrasound examination was performed to evaluate the location of the dural sac end in the lateral position with a straight back and knee, and in the lateral position with the knees, legs, and neck flexed. The level of the end of the dural sac was determined in relation to the vertebrae. Our data demonstrate that the dural sac shifts significantly cephalad in the lateral flexed position used for neuraxial blockade (p < 0.001). These results suggest that the safety margin to avoid dural puncture during hiatal or S2-3 approach for caudal block can be increased in younger children.     

Posterior epidural migration of an extruded free fragment from a lumbar disc herniation

The majority of symptomatic lumbar disc herniations are located in a posterolateral position with resultant nerve root compression. Although caudal, rostral and lateral migrations of disc fragments are common, posterior epidural migration of an extruded free fragment from a lumbar disc herniation is a rare occurrence and sometimes may cause a dural sac compression with cauda equina syndrome. This retrospective case report describes a 63-year-old man with intractable lower back pain and cauda equina syndrome. Emergency magnetic resonance imaging (MRI) revealed a posterior epidural soft tissue compressing the dural sac. The lesion was hypointense on T1-weighted images, hyperintense on T2-weighted images and showed rim enhancement after intravenous injection of gadolinium. A laminectomy at L3 was performed and the extruded disc fragment was removed with dural sac decompression. Postoperatively the patient's radicular symptoms completely resolved. At the 2-year follow-up visit, the patient had recovered full motor, sensory and urinary functions. MRI is the modality of choice in the evaluation of an extruded free disc fragment and a cauda equina compression. In such cases a wide decompressive laminectomy is recommended. Received: 13 November 2000; Accepted: 4 December 2000     

单节段与双节段腰椎管狭窄对马尾神经影响的实验研究

目的：观察不同的狭窄范围对马尾神经功能的影响。方法：采用家犬制作单、双节段腰椎管狭窄的动物模型。单环扎组在Ｌ７椎体水平用尼龙带环扎硬膜囊使其狭窄２５％,双环扎组分别在Ｌ６、Ｌ７水平环扎使其狭窄２５％。术后观察运动功能、脊髓诱发电位、球海绵体肌反射及病理变化。结果：单环扎组运动功能未见异常,诱发电位和球海绵体肌反射潜伏期轻微延长,狭窄部有轻度病理改变。双环扎组术后运动功能减弱,诱发电位和球海绵体肌反射潜伏期较单环扎组延长,狭窄部和两个狭窄部之间均出现病理改变。结论：在相同的狭窄程度下双节段比单节段狭窄对马尾神经的影响更为明显。     

Transdural cauda equina incarceration after microsurgical lumbar discectomy: case report

OBJECTIVE AND IMPORTANCE: Complications usually occur when they are least expected. We present an unusual case of nerve entrapment after microsurgical discectomy. CLINICAL PRESENTATION: A patient undergoing uneventful first lumbar microsurgical discectomy developed severe back and leg pain and a progressive neurological deficit during the first postoperative night. Herniation of cauda equina nerve roots had occurred through an unnoticed minimal defect in the dura, which had not caused cerebrospinal fluid leakage. The roots were incarcerated and swollen, and they filled the space of the resected nucleus pulposus. It was presumed that elevation of intra-abdominal pressure and consequent increased intraspinal pressure during extubation led to the herniation of arachnoid and cauda equina roots. The nerve roots were then trapped and incarcerated in the manner of bowel loops in an abdominal wall hernia. INTERVENTION: During reoperation, the nerve roots were repositioned into the dural sac. The patient recovered without further complications and without long-term sequelae. CONCLUSION: All dural tears that occur during intraspinal surgery, even if they are small and the arachnoid is intact, should be closed with stitches or at a minimum with a patch of muscle or gelatin sponge with fibrin glue. Care should be taken to avoid increased intra-abdominal pressure during extubation. Excessive pain and progressive neurological dysfunction occurring shortly after microsurgical lumbar discectomy or any intraspinal procedure is indicative of possible hemorrhage with subsequent compression of nerve roots. The case reported here provides anecdotal evidence that this situation can also be caused by a herniation of cauda equina nerve roots through a small dural defect that was not evident during the initial operation.     

Anterior lumbar interbody fusion: changes in area of the dural tube, disc height, and prevalence of cauda equina adhesion in magnetic resonance images

OBJECTIVE: Many investigators have reported satisfactory outcome in anterior lumbar interbody fusion (ALIF) performed for lumbar disc herniation or "multiply operated back" (MOB), but without comparing preoperative and postoperative dural tube area and cauda equina adhesion in magnetic resonance imaging (MRI). We conducted this study to determine these data in ALIF performed for lumbar disc herniation and MOB. METHODS: Thirty-two patients who underwent ALIF, involving 38 discs, were studied. In MRI obtained before and after surgery (interval 9-48 months, mean 19.2 months), cross-sectional areas of the lumbar dural tube were measured from axial T2-weighted images using a computer-linked digitizer. At 30 disc levels operated on, the cauda was identified in images; cauda equina adhesions were classified according to Matsui et al (grade I-III). Clinical improvement was scored. RESULTS: Bony union was observed in radiographs of all patients. Preoperative and postoperative cross-sectional areas of the lumbar dural tube were 1.32 +/- 0.4 and 1.87 +/- 0.5 cm, respectively, and expansion ratio was 1.43 +/- 0.4. Recovery did not correlate with expansion ratio. Positive correlation was noted between expansion ratio and disc height ratio. At 30 disc levels where cauda equina was identified, 22 represented grade I and 8 represented grade II. At three of the latter, prior surgery had been performed via a posterior approach. CONCLUSIONS: No significant difference was noted in occurrence of grade II adhesions between primary ALIF and ALIF performed for MOB. Dural tube expansion was accomplished even without exposure of the tube, and cauda equina adhesion was uncommon in primary ALIF.     

游离型腰椎间盘突出症的诊断与手术治疗

为了解游离型腰椎间盘突出症的诊断与治疗特点,我们对17例该病患者的临床资料进行分析。结果17例患者均得到诊断,手术效果满意。结论:根据有慢性腰腿痛病史、再度外伤后症状加剧、强迫体位、直腿抬高〈30°、屈颈试验阳性以及马尾神经损伤症状,再结合MRI或CT即可对该病作出确诊。并认为MRI是诊断该病的最佳影像学检查方法。治疗提倡早期手术,根据游离物在椎管内的位置选用对腰椎稳定性破坏低的术式。     

家犬马尾及其受压模型的建立

目的:观察家犬腰骶部神经结构与人类马尾的异同点,建立与人类马尾受压类似的动物模型,研究其病理变化。方法:废弃家犬4只经颈静脉加压灌注后,自后侧入路剖开腰骶椎管,测量椎管的直径及硬膜外间隙,观察马尾神经的组成及走行。2只家犬麻醉后自L6椎板潜行置入水囊,关闭注水,用诱发电位和MR检测。结果:犬的腰椎共有7节,椎管在L6水平横径为1.4~1.6 cm,前后径1.2~1.4 cm,硬膜外间隙约0.2 cm,共计5对神经根围绕在终丝斜向外下形成马尾。脊髓圆锥下端平L6水平。在L5,6椎板下,硬膜外间隙置入硅胶水囊后,在未注水加压时,犬的行为学及诱发电位均无改变;逐渐注水后随着压力的上升,行为学及诱发电位均有相应的改变。MR可以显示相对应的水囊所占椎管的容积。结论:家犬马尾与人类的相似,硅胶水囊置入和注水法,重复性好,动物生存率高,可以成功建立马尾慢性压迫模型。     

Cauda equina syndrome as a postoperative complication in five patients operated for lumbar disc herniation

STUDY DESIGN: A retrospective analysis of records and radiographs in five patients who developed acute cauda equina syndrome after surgery for lumbar disc herniation. OBJECTIVES: To postulate as a possible pathophysiologic mechanism the venous congestion caused by preexisting spinal stenosis and to present a management plan: extended decompression within 48 hours. SUMMARY OF BACKGROUND DATA: Cauda equina syndrome is reported as a sequela in 0.2%-1% of the surgeries for lumbar disc herniation. There is, however, no consensus on the possible pathophysiologic mechanism to the complication or to its management. METHODS: Preoperative investigations consisted of magnetic resonance imaging, or myelography and computed tomography. There was a good correlation between clinical appearance and radiographic findings in all patients. When the complication became apparent in four of the patients, they were investigated with magnetic resonance imaging and reoperated on within 48 hours with wide decompressions. RESULTS: The index operation was reported uneventful in all patients. Postoperative magnetic resonance imaging did not show the cause of the cauda equina syndrome, nor could this be established at the reoperation. Before surgery, all five patients had preexisting narrowing of the spinal canal. In no case was the lumbosacral disc the index level. Two patients recovered fully, whereas the other three experienced varying degrees of residual symptoms. There was no correlation between the end result and the delay until secondary decompression. CONCLUSION: Relative spinal stenosis may contribute to the development of cauda equina syndrome after surgery for lumbar disc herniation. A venous congestion can be triggered by postoperative edema, leading to nerve root ischemia. The treatment of choice seems to be extended decompression within 48 hours.     

Percutaneous endoscopic lumbar discectomy and interbody fusion with B-Twin expandable spinal spacer

Background  

Posterior lumbar interbody fusion (PLIF) is biomechanically sound as it ablates the degenerated disc, restores the intervertebral height, relieves foraminal stenosis, and positions the bone graft along the weight-bearing axis. But this conventional procedure also results in significant traction on the dural sac and the cauda equina and is thereby a potential source of neurologic damage. Therefore, we performed a minimally invasive technique: percutaneous endoscopic discectomy and interbody fusion (PEDIF) with B-Twin expandable spinal spacer (B-twin ESS) to treat symptomatic lumbar degenerative disc disease and explored the clinical outcome.     

Cauda equina syndrome secondary to posterior epidural migration of a lumbar disc fragment: a rare phenomenon

Most symptomatic lumbar disc herniations occur in a postero-lateral direction. Disc fragments also commonly migrate both caudally and rostrally. The extrusion of lumbar discs is usually limited by the posterior longitudinal ligament and its attachments. Migration of disc tissue around the dural sac to the posterior epidural space is a rare occurrence. There have been even fewer reports, in the published literature, of cauda equina syndrome resulting from posterior epidural migration of lumbar disc fragments. We present a case of cauda equina syndrome due to compression of the neural elements by a large fragment of sequestered lumbar disc tissue, which had migrated to the posterior epidural space.     

Assessment of lumbar spinal canal stenosis by magnetic resonance phlebography

 There is evidence to suggest that cauda equina intermittent claudication is caused by local circulatory disturbances in the cauda equina as well as compression of the cauda equina. We evaluated the role of magnetic resonance phlebography (MRP) in identifying circulatory disturbances of the vertebral venous system in patients with lumbar spinal canal stenosis. Extensive filling defects of the anterior internal vertebral venous plexus were evident in patients with lumbar spinal canal stenosis (n = 53), whereas only milder abnormalities were noted in patients with other lumbar diseases (n = 16) and none in normal subjects (n = 13). The extent of the defect on MRP correlated with the time at which intermittent claudication appeared. In patients with lumbar spinal canal stenosis, extensive defects of the internal vertebral venous plexus on MRP were noted in the neutral spine position, but the defect diminished with anterior flexion of the spine. This phenomenon correlated closely with the time at which intermittent claudication appeared. Our results highlight the importance of MRP for assessing the underlying mechanism of cauda equina intermittent claudication in patients with lumbar spinal canal stenosis and suggest that congestive venous ischemia is involved in the development of intermittent claudication in these patients. Received: January 16, 2002 / Accepted: August 5, 2002 Offprint requests to: M. Manaka     

Cerebrospinal fluid volume and nerve root vulnerability during lumbar puncture or spinal anaesthesia at different vertebral levels

Cerebrospinal fluid (CSF) and nerve root volumes within the lumbosacral dural sac were estimated at various vertebral levels, in an attempt to determine any possible relevance to the incidence of nerve root trauma during lumbar puncture or spinal anaesthesia. Magnetic resonance images from seven patients were studied. Volumes were calculated by semi-automatic threshold segmentation combined with manual editing of each slice. The mean dural sac volume from S1 to T12 was 42.8±5.8 ml and the mean CSF volume 34.3±5.1 ml with the mean root volume being 10.4±2.2 cm(3). The mean CSF volume per vertebral segment ranged from 4.3±0.7 ml at L5, to 5.8±2.5 ml at L1, with high inter-individual variability. The mean root volume ranged from 0.6±0.1 cm(3) at L5 to 2.4±0.5 cm(3) at T12. The conus medullaris was located at L1 in four of the five patients scanned at upper lumbar levels, and at the lower border of L2 in the other. Vulnerability to nerve root damage was expressed as the Vulnerability Index (%), being defined as the ratio of root volume to dural sac volume (CSF volume + root volume). The value ranged between 7 and 14% at L5, increasing rostrally to 30 to 43% at T12. Caution is obviously required in high punctures to avoid contact with the conus medullaris, but the cauda equina is also vulnerable to contact with more caudal punctures and had a Vulnerability Index of about 25% at L4, that increased rostrally.     

Redundant nerve roots in patients with degenerative lumbar spinal stenosis

Extensive fundamental and clinical investigations have been performed concerning redundant nerve roots (RNR) and the pathogenesis of cauda equina claudication (CEC) in degenerative lumbar canal stenosis (DLCS). These investigations consisted of (1) anatomic observations on RNR in 117 fixed cadaveric specimens, (2) myelographic study in 117 patients with or without DLCS, (3) operative observation on neural elements with special reference to the cauda equina in 56 DLCS patients (including a postoperative follow-up), and (4) electrophysiologic tests using spinal cord action potential recording under walking load preoperatively and intraoperative measurement of nerve conduction velocity of RNR. The RNR have neuronal losses resulting from a longer duration stenosis that suggests a sort of friction neuritis. Complicated factors contribute to the pathogenesis of CEC and the development of root gripping, such as the magnitude of RNR, the extent of the stenosis, a narrowed sac, age-dependent axial shortening of the spinal canal, and dynamic or postural factors. In cases with severe RNR, satisfactory operative results can be obtained only after thorough decompression with dural incision.     

Simultaneous intra‐operative repair for inadvertent dural tear under posterior lumbar disk scope

Objective: To introduce a microsurgical suture technique for repair of dural tear under posterior lumbar disk scope. Methods: Micro endoscopic discectomy was performed on a 26‐year‐old male under local anesthesia. During the operation, an irregular tear of about 1.0 cm was inadvertently made in the dura.The cauda equina herniated through the tear with fluctuations and leakage of cerebrospinal fluid. The tear was successfully sutured with a 7/0 microsurgical thread which was held by small disk forceps in a parallel position. Results: Once the repair had been performed, minor cerebrospinal fluid leakage persisted but there was no herniation of the cauda equina. The original planned operation was completed smoothly under posterior lumbar disk scope. Conclusion: The microsurgical suture technique for dural tear under posterior lumbar disk scope described here is simple and reliable.     

The effect of Lipo prostaglandin E1 on cauda equina blood flow in patients with lumbar spinal canal stenosis: myeloscopic observation.

STUDY DESIGN: Myeloscopic examination was performed to observe the cauda equina in patients with lumbar spinal canal stenosis before and after treatment with Lipo prostaglandin E1, a strong peripheral vasodilator. OBJECTIVES: The purpose of this study was to clarify the effects of Lipo prostaglandin E1 on blood flow in the cauda equina in patients with lumbar spinal canal stenosis. SETTING: Japan, Kagoshima METHODS: We performed myeloscopic observations of morphological changes in blood vessels running along the cauda equina in 11 patients with lumbar spinal canal stenosis before and after treatment with Lipo prostaglandin E1. RESULTS: In six of these patients, dilation of the running blood vessels was observed immediately after administration. In all of the patients who exhibited a dilation of vessels on the surface of the cauda equina, intermittent claudication and lower extremity pain and/or numbness lessened immediately after examination. However, none of the patients who exhibited no morphological changes in the vessels along the cauda equina after administration of Lipo prostaglandin E1 experienced any improvement of symptoms at the time of examination. CONCLUSION: Results of this study suggest that Lipo prostaglandin E1 may enhance blood flow in the cauda equina and improve clinical symptoms in some patients with lumbar spinal stenosis.     

腰椎过伸位MRI在腰椎管狭窄诊断中的临床应用

目的：通过腰椎过伸位MRI检查,研究腰椎过伸位下椎管狭窄程度的变化,评估腰椎过伸位MRI扫描对腰椎管狭窄的诊断价值。方法：2018年9月至2020年2月,纳入26例腰椎管狭窄进行腰椎中立位和过伸位MRI扫描,男11例,女15例;年龄43~85（64.00±10.37）岁。由于6例患者在过伸位下诱发并加重了腰腿痛症状,无法采集到合格的MRI数据,最终完成检查共采集到20例患者的合格数据,采用Mimics 21.0医学图像处理软件测量腰椎管狭窄的相关诊断参数,统计分析其变化规律,评价过伸位下腰椎管的狭窄程度和神经受压情况。结果：腰椎管矢径及横截面积不随体位发生明显变化;硬膜囊矢径、盘黄间隙在过伸位时均有不同程度变小。结论：对于腰椎管狭窄的影像学诊断,腰椎过伸位MRI扫描可较好地补充常规中立位MRI检查,对腰椎管狭窄程度的临床诊断更具敏感性。     

Synovial cysts and the lithotomy position causing cauda equina syndrome

We describe a case of cauda equina syndrome caused by synovial cysts and the lithotomy position. A transurethral resection of the prostate was performed under spinal anesthesia in the lithotomy position. We believe that this is the first case report of facet joint synovial cysts and the lithotomy position causing ischemic neurologic injury to the cauda equina. Other etiologies such as needle trauma, neurotoxicity, hematoma, and abscess were not evident. We believe that positioning the patient in the lithotomy position narrowed the cross-sectional area of the spinal canal in a patient with a coexisting critically stenosed lumbar spinal canal. The resultant mechanical pressure caused an ischemic compression injury to the cauda equina.     

A case of indirect cauda equina syndrome from metastatic prostate cancer

We report the case of a patient with metastatic hormone refractory prostate cancer in whom “indirect” cauda equina syndrome developed concurrent with multilevel spinal cord compression (SCC). Three months after his first positive bone scan, a 65-year-old otherwise healthy man presented with severe back pain, bilateral lower extremity paresthesias, leg weakness and urinary retention. Magnetic resonance imaging (MRI) showed a dural-based mass causing SCC at the T9, T10 and T11 vertebrae, with a normal cauda equina. He received corticosteroids and palliative external beam radiotherapy, resulting in good pain control and gradual improvement in his neurological symptoms. He did well for 8 months, at which time his residual bilateral leg weakness abruptly worsened and he experienced numbness, paresthesias, urinary incontinence and constipation. Repeat MRI showed progression of epidural metastatic disease compressing the spinal cord or thecal sac at 7 thoracic vertebral levels. The cauda equina was also distorted and flattened without evidence of direct solid tumour impingement. We hypothesized that the etiology was increased intrathecal pressure due to disrupted cerebrospinal fluid flow resulting from multiple levels of upstream thecal sac compression. It is essential to image the entire spinal cord and cauda equina when patients with metastatic bone disease present with neurological symptoms to institute correct treatment and preserve function and mobility.