Somatosensory evoked potential

Summary Somatosensory evoked potentials (SSEPs) have been used to help minimize neurologic morbidity during spinal surgery. While this is a sensory test it has been used as an inference of motor function. The failure to always achieve the latter goal has resulted in some pessimism regarding the value of this test. In this series of 161 operations in 150 patients, it was demonstrated that SSEPs were recordable under anesthesia in 87% of patients. Of these patients, 12% had their spinal surgery interrupted due to significant neurophysiologic changes; of these patients, 18% had new neurologic deficits postoperatively. There were no cases with new neurologic deficits who had no changes in their SSEPs. It was concluded that SSEP monitoring may be helpful in identifying potentially neurologically threatening surgical maneuvers in a significant number of patients.     

Enlargement of cervical spinal cord correlates with improvement of motor function in upper extremities after laminoplasty for cervical myelopathy

OBJECTIVE: The correlation between postoperative spinal cord enlargement at the most compressive disc level and clinical outcome is controversial. The relationship between spinal cord enlargement at neurologically symptomatic disc level and clinical recovery has not been explored. The purpose of this study was to clarify the relationship between postoperative spinal cord enlargement at neurologically symptomatic disc level and neurologic outcome. METHODS: We studied 55 consecutive patients between 1995 and 2002. All patients underwent preoperative neurologic examination to determine the neurologically symptomatic disc level of the spinal cord and computed tomographic myelography twice before and 4 weeks after laminoplasty. The cross-sectional areas of both spinal cord and dural sac from C3/4 to C7/T1 disc levels were measured on computed tomographic myelography images. The Japanese Orthopedic Association scoring system was used for clinical evaluation before and 1 year after surgery. RESULTS: Total score improved significantly from 10.2+/-2.8 (SD) to 13.0+/-3.0 after operation. Motor and sensory function scores of upper and lower extremities also improved significantly. The enlargement of spinal cord area at the neurologically symptomatic disc level correlated significantly with improvement in motor function scores of upper extremities (rs=0.421 P=0.0052). However, there were no significant relationships between the enlargement of the spinal cord at the most compressive disc level or that at the dural sac and any categories of Japanese Orthopedic Association scoring system. CONCLUSION: Postsurgical enlargement of the cervical spinal cord at the neurologically symptomatic disc level at 4 weeks postoperatively correlated with recovery of motor function of the upper extremities at 1 year.     

纳洛酮治疗急性脊髓损伤的临床观察

作者以甲基强的松龙为参照，观察了１４例急性脊髓损伤患者应用纳洛酮后的神经功能恢复。结果表明，急性脊髓损伤６ｈ内的患者，入院后即在１５ｍｉｎ内通过外周静脉滴注纳洛酮５．４μｇ／ｋｇ，暂停４５ｍｉｎ后以４μｇ／ｋｇ／ｈ维持２３ｈ。给药后６周观察，同对照组相比，纳洛酮治疗患者的触觉、痛觉评分明显提高，同对照组相比，甲基强的松龙组给药后６周及６月观察，运动功能、触觉、痛觉功能评分均显著提高。结论：急性脊髓损伤后６ｈ内外周静脉给予纳洛酮也可改善急性脊髓损伤患者的神经功能，但作用不如甲基强的松龙显著。     

颈椎颈髓损伤后外科治疗时间对预后的影响

目的:前瞻性比较颈椎颈髓损伤患者在3d内与10~14d内进行外科干预后神经功能恢复的情况。方法:32名急性颈椎颈髓损伤的患者根据入选标准随机分为早期手术组(3d内手术)和择期手术组(10~14d内手术)。分别记录患者术前和术后2年的Frankel分级和感觉、运动评分(依据美国脊髓损伤学会的标准)。结果:与术前相比,两组患者术后的感觉、运动评分均有明显改善(P<0.01),Frankel分级的改善程度早期手术组明显优于择期手术组(P<0.01)。结论:急性颈椎颈髓损伤在3d内进行手术治疗者神经功能恢复的结果优于10~14d内行手术者。因此,颈椎颈髓损伤后应尽可能地早期进行外科干预。     

Surgical treatment of posttraumatic cystic and tethered spinal cords

Posttraumatic syringomyelia as a cause of progressive neurologic deterioration has been well described. More recently, the noncystic posttraumatic tethered cord has been associated with identical progressive neurologic deterioration. A retrospective analysis of patients treated surgically with spinal cord untethering and/or cyst shunting to arrest a progressive myelopathy from a posttraumatic tethered and/or cystic cord was performed. Emphasis was on outcome using the American Spinal Injury Association (ASIA) sensory and motor scoring systems. During an 18-month period from May 1993 to December 1994, 70 patients with spinal cord injury were operated upon for tethered and/or cystic spinal cords because of a progressive myelopathy and deteriorating ASIA sensory/motor scores. Fifty-nine patients had follow-up data 1 year postoperatively. At the 1 year follow-up, there was small improvement in light touch sensory scores (0.67 points), pinprick scores (1.3 points), and motor scores (0.41 points) demonstrating that the progression of the myelopathic process was arrested. Thirty-four of these 59 patients had no previous surgery to their spinal cords. At 1 year follow-up, light touch scores improved on average 2.38 points, pinprick scores 3.88 points (p < 0.05), and motor scores 1.47 points, suggesting better outcome with first-time surgery. Of this latter group, 64.3% regained a lost function, 62.5% saw improvement in spasticity, 55.6% had substantial improvement in neurogenic pain, and 95.8% felt that surgery prevented further neurologic deterioration.     

The role of transcranial motor evoked potentials in predicting neurologic and histopathologic outcome after experimental spinal cord ischemia

BACKGROUND: Monitoring of myogenic motor evoked potentials to transcranial stimulation (tcMEPs) is clinically used to assess motor pathway function during aortic and spinal procedures that carry a risk of spinal cord ischemia (SCI). Although tcMEPs presumably detect SCI before irreversible neuronal deficit occurs, and prolonged reduction of tcMEP signals is thought to be associated with impending spinal cord damage, experimental evidence to support this concept has not been provided. In this study, histopathologic and neurologic outcome was examined in a porcine model of SCI after different durations of intraoperative loss of tcMEP signals. METHODS: In 15 ketamine-sufentanil-anesthetized pigs (weight, 35-45 kg) the spinal cord feeding lumbar arteries were exposed. tcMEP were recorded from the upper and lower limbs. Under normothermic conditions, animals were randomly allocated to undergo short-term tcMEP reduction (group A, < 10 min, n = 5) or prolonged tcMEP reduction (group B, 60 min, n = 10), resulting from temporary or permanent clamping of lumbar segmental arteries. Neurologic function was evaluated every 24 h, and infarction volume and the number of eosinophilic neurons and viable motoneurons in the lumbosacral spinal cord was evaluated 72 h after induction of SCI. RESULTS: In all animals except one, segmental artery clamping reduced tcMEP to below 25% of baseline. All but one animal in group A had reduced tcMEP for less than 10 min and had normal motor function and no infarction at 72 h after the initial tcMEP reduction. Seven animals in group B (70%) had reduced tcMEP signals for more than 60 min and were paraplegic with massive spinal cord infarction at 72 h. Two animals (one in both groups) had tcMEP loss for 40 min, with moderate infarction and normal function. In general, histopathologic damage and neurologic dysfunction did not occur when tcMEP amplitude recovered within 10 and 40 min after the initial decline, respectively. CONCLUSION: Prolonged reduction of intraoperative tcMEP amplitude is predictive for postoperative neurologic dysfunction, while recovery of the tcMEP signal within 10 min after the initial decline corresponds with normal histopathology and motor function in this experimental model. This finding confirms that intraoperative tcMEPs have a good prognostic value for neurologic outcome during procedures in which the spinal cord is at risk for ischemia.     

Intraoperative neurophysiologic monitoring during spinal surgery

Intraoperative neurophysiologic monitoring (IONM) is a battery of neurophysiologic tests used to assess the functional integrity of the spinal cord, nerve roots, and other peripheral nervous system structures (eg, brachial plexus) during spinal surgery. The underlying principle of IONM is to identify emerging insult to nervous system structures, pathways, and/or related vascular supply and to provide feedback regarding correlative changes in neural function before development of irreversible neural injury. IONM data provide an opportunity for intervention to prevent or minimize postoperative neurologic deficit. Current multimodality monitoring techniques permit intraoperative assessment of the functional integrity of afferent dorsal sensory spinal cord tracts, efferent ventral spinal cord motor tracts, and nerve roots. Combined use of these techniques is useful during complex spinal surgery because these monitoring modalities provide important complementary information to the surgery team.     

Neurophysiological monitoring for safe surgical tethered cord syndrome release in adults

BACKGROUND: Release of tethered spinal cord by sectioning of the filum terminale carries a significant risk of injury to the neighboring motor and sensory nerve roots. Intraoperative neurophysiological monitoring techniques can help to minimize these adverse neurologic outcomes. METHODS: We performed a retrospective review of 67 consecutive patients undergoing tethered cord release. We excluded 52 pediatric patients which limited our study to 15 adult patients treated during a four year period, including patients with a thick filum, low lying conus, myelomeningocele, filum tumor, spinal cord malformation, and/or lipoma. Clinical outcomes were determined from postoperative follow-up visits. Two patients were lost to follow up and were excluded from the clinical outcome analysis. Electrical stimulation of the filum terminale and lumbo-sacral nerve roots in conjunction with electromyogram (EMG) recording was performed intraoperatively. RESULTS: The mean electrical threshold for EMG response during stimulation of the filum terminale was 37.1 volts (V), range 15 to 100 V. In comparison, the lowest threshold obtained by direct stimulation of the ventral nerve roots was a mean of 1.46 V, with a range of 0.1 to 7 V. More than 70% of the patients studied demonstrated a filum to motor root threshold ratio of 100:1 or greater. No patient developed new neurologic symptoms or signs postoperatively. Bowel and bladder function improved in 46% of patients, back pain in 39% and motor function in 31%. Eight percent reported decline in bladder control and worsening back pain postoperatively. CONCLUSIONS: The often dramatic difference in the threshold of the filum terminale and adjacent motor nerve roots (100:1) helps to identify, isolate, and safely section the filum terminale. Tethered cord release using intraoperative neurophysiological monitoring is safe and in the majority of cases leads to improvement or at least, stabilization of neurologic function. Monitoring prevented intraoperative nerve root injury that might have resulted in immediate onset of new neurologic deficits caused by the surgical procedure.     

The role of directly applied hypothermia in spinal cord injury

STUDY DESIGN: The effect of intense local hypothermia was evaluated in a precision model of spinal canal narrowing and spinal cord injury in rats. The spinal cord injury was cooled with a custom cooling well used over the epidural surface. Basso, Beattie, and Bresnahan (BBB) motor scores and transcranial magnetic motor-evoked potential (tcMMEP) responses were used after injury to accurately evaluate neurologic recovery. OBJECTIVE: This study was undertaken to determine whether the prognosis for neurologic recovery in a standardized rat spinal cord injury model is altered by the direct application of precisely controlled hypothermia to the area of injury. SUMMARY OF BACKGROUND DATA: The role of hypothermia in the treatment of spinal cord injuries with neurologic deficits remains undefined. Hypothermia may decrease an area of spinal cord injury and limit secondary damage, therefore improving neurologic recovery. However, it has been difficult to consistently apply localized cooling to an area of spinal cord injury, and the use of systemic hypothermia is fraught with complications. This fact, along with the unavailability of a precise spinal cord injury model, has resulted in inconsistent results, both clinically and in the laboratory. In a rat model of spinal cord injury, 37 C and 19 C temperatures were used to study the role of hypothermia on neurologic recovery. METHODS: Male Spraque-Dawley rats (n = 52; weight, 277.7 g) were anesthetized with pentobarbital and subjected to laminectomy at T10. The rats were divided into three groups: 1) placement of a 50% spacer in the epidural space (16 rats), 2) severe (25 g/cm) spinal cord injury (16 rats), 3) 50% spacer in combination with spinal cord injury (16 rats). Eight rats in each group were tested at two temperatures: normothermic (37 C) and hypothermic (19 C). With the use of a specially designed hypothermic pool placed directly over the spinal cord for 2 hours, epidural heating to 37 C, and epidural cooling to 19 C was accomplished. Simultaneous measurements of spinal cord and body temperatures were performed. The rats underwent behavior testing using the BBB motor scores and serial tcMMEPs for 5 weeks. Statistical methods consisted of Student's t tests, one-way analysis of variance, Tukey post hoc t tests and chi2 tests. RESULTS: There was a significant improvement in motor scores in rats subjected to hypothermia compared with those that were normothermic after insertion of a 50% spacer. This improvement was observed during the 5-week duration of follow-up. In the severe spinal cord injury group and the spinal cord injury-spacer groups, no significant improvement in motor scores were obtained when the spinal cord was exposed to hypothermia. CONCLUSION: The results demonstrate that there is a statistically significant (P < 0.05) improvement in neurologic function in rats subjected to hypothermia (19 C) after insertion of a spacer that induced an ischemic spinal cord injury. This indicates that directly applied hypothermia may be beneficial in preventing injury secondary to ischemic cellular damage. The data demonstrated minimal therapeutic benefit of hypothermia (19 C) after a severe spinal cord injury.     

Surgical Treatment of Posttraumatic Cystic and Tethered Spinal Cords

Abstract

Posttraumatic syringomyelia as a cause of progressive neurologic deterioration has been well described. More recently, the noncystic posttraumatic tethered cord has been associated with identical progressive neurologic deterioration.

A retrospective analysis of patients treated surgically with spinal cord untethering and/or cyst shunting to arrest a progressive myelopathy from a posttraumatic tethered and/or cystic cord was performed. Emphasis was on outcome using the American Spinal Injury Association (ASIA) sensory and motor scoring systems.

During an 18-month period from May 1993 to December 1994, 70 patients with spinal cord injury were operated upon for tethered and/or cystic spinal cords because of a progressive myelopathy and deteriorating ASIA sensory/motor scores. Fifty-nine patients had follow-up data 1 year postoperatively. At the 1 year follow-up, there was small improvement in light touch sensory scores (0.67 points), pinprick scores (1.3 points), and motor scores (0.41 points) demonstrating that the progression of the myelopathic process was arrested. Thirty-four of these 59 patients had no previous surgery to their spinal cords. At 1 year follow-up, light touch scores improved on average 2.38 points, pinprick scores 3.88 points (p < 0.05), and motor scores 1.47 points, suggesting better outcome with first-time surgery. Of this latter group, 64.3% regained a lost function, 62.5% saw improvement in spasticity, 55.6% had substantial improvement in neurogenic pain, and 95.8% felt that surgery prevented further neurologic deterioration.     

Traumatic division of the spinal cord demonstrated by magnetic resonance imaging. Report of two cases

Magnetic resonance imaging (MRI) of the spine is a new imaging technique that allows greater visualization of the spinal cord than other imaging modalities. This article reports on two cases of traumatic division of the spinal cord demonstrated by MRI. Both patients had complete transection of the spinal cord and did not have neurologic functional recovery distal to the spinal cord transection. MRI is applicable to diagnosis in acute conditions and to reveal division of the spinal cord, allowing prediction of an unlikely chance of neurologic recovery.     

Failure of motor evoked potentials to predict neurologic outcome in experimental thoracic aortic occlusion

Motor evoked potential monitoring was tested as an alternative to somatosensory evoked potential monitoring in evaluating spinal cord function during thoracic aortic occlusion in dogs. Twenty-seven animals underwent 60 minutes of cross-clamping of the proximal descending thoracic aorta with (n = 18) or without (n = 9) cerebrospinal fluid drainage. Spinal cord blood flow was measured with microspheres, and neurologic outcome was evaluated at 24 hours with Tarlov's scoring system. Cerebrospinal fluid drainage improved neurologic outcome (p less than 0.05). Motor evoked potentials recorded over the lumbar spinal cord were lost in 9 of 20 dogs with ischemic cord injury and were not lost in any of the 7 dogs that were neurologically normal. Somatosensory evoked potential were lost in 19 of 20 paraplegic/paraparetic dogs and lost in 3 of 7 normal dogs (p less than 0.01). After reperfusion, motor evoked potentials returned in all nine neurologically injured dogs that lost the potentials and were still present at 24 hours. Changes in amplitude, latency, or time until loss or return of motor evoked potentials or somatosensory evoked potentials did not predict neurologic injury. Loss of somatosensory evoked potentials had a high sensitivity (95%) but had low specificity (67%) because of peripheral nerve ischemia. Loss of motor evoked potentials recorded from the spinal cord had high specificity (100%) but a low sensitivity (46%) and was therefore not a reliable predictor of neurologic injury. Return of motor evoked potentials during reperfusion did not correlate with functional recovery. Motor evoked potentials stimulated in the cortex and recorded from the spinal cord had low overall accuracy (59%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Intrathecal Magnesium Sulfate Administration at the Time of Experimental Ischemia Improves Neurological Functioning by Reducing Acute and Delayed Loss of Motor Neurons in the Spinal Cord

Background: In this study, the authors determined the effect of magnesium sulfate on intrathecal glutamate concentrations, hindlimb motor function, and histopathology after a transient episode of spinal cord ischemia.

Methods: Fifty-two New Zealand White rabbits underwent spinal cord ischemia for 30 min. Fifteen minutes before ischemia, animals received intrathecal magnesium sulfate (MgSO4) (3 mg/kg) or placebo (artificial cerebrospinal fluid). Intrathecal microdialysis samples were measured for glutamate using high-performance liquid chromatography. Neurologic function and spinal cord histopathology were assessed throughout the recovery period.

Results: Intrathecal glutamate levels in placebo-treated animals were higher after spinal cord ischemia compared with sham- and MgSO4-treated animals. MgSO4-treated animals had increased lower extremity motor function compared with the placebo group (64.7% vs 14.3%, P < 0.01). Histologic examination of placebo-treated animals revealed significant motor neuron cell loss at thoracolumbar levels by Day 7 (P < 0.05), whereas lower lumbar regions displayed significant neuron loss on Day 1. Spinal cords from MgSO4-treated animals exhibited less neuronal loss in lumbar regions. Similar effects were present in the thoracolumbar segments on Day 7. A significant correlation existed between diminished neuronal loss and hind leg movement (Tarlov score) and demonstrates that the neurologic outcome after MgSO4 treatment was related to lower lumbar ventral horn cell survival (r2 = 0.812, P < 0.001).     

Nerve repair using acidic fibroblast growth factor in human cervical spinal cord injury: a preliminary Phase I clinical study

OBJECT: The aim of this study was to assess functional outcomes of nerve repair using acidic fibroblast growth factor (FGF) in patients with cervical spinal cord injury (SCI). METHODS: Nine patients who had cervical SCI for longer than 5 months were included in pre- and postoperative assessments of their neurological function. The assessments included evaluating activities of daily living, associated functional ability, and degree of spasticity, motor power, sensation, and pain perception. After the first set of assessments, the authors repaired the injured segment of the spinal cord using a total laminectomy followed by the application of fibrin glue containing acidic FGF. Clinical evaluations were conducted 1, 2, 3, 4, 5, and 6 months after the surgery. Preoperative versus postoperative differences in injury severity and grading of key muscle power and sensory points were calculated using the Wilcoxon signed-rank test. RESULTS: The preoperative degree of injury severity, as measured using the American Spinal Injury Association (ASIA) scoring system, showed that preoperative motor (52.4 +/- 25.9 vs 68.6 +/- 21.5), pinprick (61.0 +/- 34.9 vs 71.6 +/- 31.0), and light touch scores (57.3 +/- 33.9 vs 71.9 +/- 30.2) were significantly lower than the respective postoperative scores measured 6 months after surgery (p = 0.005, 0.012, and 0.008, respectively). CONCLUSIONS: Based on the significant difference in ASIA motor and sensory scale scores between the preoperative status and the 6-month postoperative follow-up, this novel nerve repair strategy of using acidic FGF may have a role in the repair of human cervical SCI. Modest nerve regeneration occurred in all 9 patients after this procedure without any observed adverse effects. This repair strategy thus deserves further investigation, clinical consideration, and refinement.     

脊髓型颈椎病脊髓受压征象的MRI分级及其临床意义

目的:建立脊髓型颈椎病(cervical spondylotic myelopathy,CSM)脊髓受压征象的MRI分级系统,探讨其可靠性及其与年龄、病程和JOA评分的相关性。方法:收集2010年1月～2011年9月就诊的78例多节段CSM患者的颈椎MRI资料,男51例,女27例;年龄42～77岁,平均55.1岁;病程0.25～276个月,平均48.8个月。以颈椎MRI中脊髓形态、脊髓信号、脊髓与硬膜囊关系作为分级依据征象,将每个征象按照其严重程度分为3个等级,相应赋予0～2分,按3个征象总分划分为四级:0级,0分;Ⅰ级,1～2分;Ⅱ级,3～4分;Ⅲ级,5～6分。由3位初、中、高级职称医师对78例患者的颈椎MRI从C2/3～C6/7进行2次独立分级和1次共同分级,Kappa分析评价每位医师前后2次之间及3位医师之间分级结果的一致性。将3位医师对三个征象共同分级的结果进行Spearman相关分析,同时将患者年龄、病程、术前JOA评分与分级结果进行Spearman相关分析。结果:3位医师分别2次对78例患者的390个节段进行分级,0级82～94个(21.03%～24.10%),Ⅰ级112～126个(28.72%～32.31%),Ⅱ级111～137个(28.46%～35.13%),Ⅲ级47～70个(12.05%～17.95%)。同一医师前后2次分级一致的节段占74.6%～78.5%,Kappa值为0.657～0.706;不同级别医师分级一致的节段占71.5%～76.7%,Kappa值为0.614～0.683。三个征象分级的结果之间相关系数分别为0.552、0.603、0.577,呈显著性正相关(P<0.05)。患者年龄、病程与3位医师共同分级结果的相关系数分别为0.372～0.511、0.388～0.498,呈显著性正相关(P<0.05);术前JOA评分与3位医师共同分级结果的相关系数为-0.409～-0.546,呈显著性负相关(P<0.05)。结论:依据脊髓形态、脊髓信号、脊髓与硬膜囊关系建立的脊髓型颈椎病脊髓受压征象的MRI分级系统具有良好的一致性,其与患者年龄、病程呈正性相关,而与术前JOA评分呈负性相关,对脊髓受压后病变的严重程度评估和研究有指导意义。     

ASIA脊髓损伤分类标准在颈髓损伤患者神经功能评定中的应用

目的：探讨ASIA标准在颈髓损伤患者神经功能评估中的意义。方法：应用ASIA标准对139例急性颈髓损伤患者的神经功能情况进行回顾性评估。结果：82例完全性脊髓损伤患者中5例逆转为不完全性损伤，77例无逆转者随访时ASIA感觉、运动评分有明显增加。57例不完全性颈髓损伤患者感觉、运动功能改善明显优于完全性损伤患者。结论：完全性颈髓损伤患者可能逆转为不完全性颈髓损伤，并且可有明显节段性神经功能恢复。在脊髓损伤神经功能评定中，ASIA感觉、运动评分具有重要意义。     

Infolding of the ligamentum flavum: a cause of spinal cord compression after reduction of cervical facet injuries

Controversy exists regarding management of cervical facet injuries. Previous literature has focused on associated disc herniations reported to cause neurologic injury upon reduction. Although rupture of the ligamentum flavum has been noted with these injuries, its clinical significance has not been examined. In this case report, we present two patients in whom neurologic deterioration occurred due to infolding of the torn ligamentum flavum with spinal cord compression after reduction of cervical facet subluxations. Both had large flaps of ligamentum flavum arising from the caudal lamina which infolded upon reduction and became trapped between the spinal cord and cephalad lamina. Both patients regained normal motor function after removal of the pathologically infolded ligamentum. Neither patient had a disc herniation, hypotensive/anemic/hypoxic event, or epidural hematoma that could have otherwise been causative of the neurologic deficit. Pathologic infolding of ligamentum flavum, in addition to extruded disc herniations, should be recognized as another potential cause for spinal cord compression with reduction of cervical facet injuries. In particular, if there is a long flap of flavum arising from the caudal lamina poised to become entrapped in the spinal canal with reduction and the patient has a congenitally narrow canal, the surgeon should consider removal of the ligamentum flavum prior to reduction.     

Vascular malformations of the spinal cord and dura

Current techniques of diagnosis and treatment allow for earlier detection, precise delineation of the vascular anatomy, and, most important, successful treatment of most patients with spinal AVMs. Magnetic resonance imaging is useful in the initial assessment of patients with progressive myelopathy but cannot replace myelography or arteriography in screening patients who may have a spinal AVM. The most common variety of spinal AVM is a dural arteriovenous fistula. Dural arteriovenous fistulas cause cord injury by producing venous congestion, and symptoms can be reversed by elimination of venous congestion of the spinal cord. Dural arteriovenous fistulas can be treated successfully by interrupting the arteriovenous fistula either in the dura or by disconnecting the dural fistula from the coronal venous plexus in the subarachnoid space. This can be done by interrupting the medullary vein that drains the arterial blood from the dural fistula into the coronal venous plexus of the spinal cord. Stripping of the engorged venous network on the surface of the spinal cord is unwarranted and may cause further cord injury. In dural arteriovenous fistulas embolization is often beneficial in patients with acute neurologic deterioration, to permit time for stabilization and improvement in spinal cord hemodynamics and in cord function before neurosurgical intervention is undertaken. Embolization also may be indicated in patients with intradural spinal AVMs in which surgery cannot be performed safely. Although embolic occlusion does not permanently occlude most intradural AVMs, it often permits stabilization of neurologic function and may be repeated later if neurologic dysfunction returns or progresses. Although the outcome after treatment is dependent on the type and location of the spinal AVM, as in most treatable neurologic disorders the functional outcome of patients with spinal AVMs is directly related to their neurologic condition at the time of treatment. Patients with minimal dysfunction, and with easily accessible AVMs, such as dural arteriovenous fistulas, have the greatest chance for useful recovery or stabilization. Since these patients represent the largest number of patients with spinal AVMs, they must be diagnosed and treated early to achieve the best possible outcome.     

Assessment of spinal cord ischemia by means of evoked potential monitoring during thoracoabdominal aortic surgery

Besides renal failure and mesenteric infarction, spinal cord ischemia is the most dreaded complication after thoracoabdominal aortic surgery. Several techniques have been developed to improve neurologic outcome of these massive surgical procedures, including pharmacologic adjuncts, epidural cooling, distal aortic perfusion, cerebrospinal fluid drainage, and reattachment of segmental arteries. The authors developed a technique to assess spinal cord integrity as part of the surgical protocol, dictating operative strategies to restore blood supply to the endangered grey matter. Monitoring motor evoked potentials (MEPs) was performed in experimental studies and in 170 patients with a thoracoabdominal aortic aneurysm. The surgical protocol included left heart bypass and cerebrospinal fluid drainage, and MEP monitoring was applied to identify critical intercostal and lumbar arteries. Based on MEPs, the aggressive surgical approach resulted in a significant reduction of neurologic complications (2.3%).     

关于颈脊髓损害功能评定标准的讨论：（介绍一种新标准—四十分法）

本文综述了国内外常用的几种关于脊髓损害的功能评定方法，并提出了一个新的四十分评定法。此方法用数字描述颈脊髓损害患者的四肢运动功能、感觉和括约肌功能情况，较细致全面地反映病变的程度，把颈脊髓损害所造成的残疾分为四级，与中残联制定的肢体残疾整体功能评定相一致。经实践证明四十分法对颈脊髓损害功能的评定是较为合理简便和准确的。