颈椎病前路手术中体感诱发电位监护临床研究

目的探讨体感诱发电位监护(SSEP)在颈椎病前路手术中的应用价值。方法收治颈椎病前路手术患者142例,年龄37~75岁,男96例,女46例。神经根型颈椎病35例,脊髓型颈椎病107例。对照组83例无SSEP监护,监护组59例。在麻醉诱导后和摆放体位前确立SSEP基线,波幅降低50%或潜伏期延长10%为报警标准。记录SSEP报警因素及改善措施,术后明确有无医源性神经损伤。结果对照组无医源性神经损伤。监护组:真阳性2例出现报警,采取措施后解除报警;假阳性0例;真阴性56例SSEP无报警,无医源性神经损伤;假阴性1例SSEP无报警,术后右侧三角肌麻痹;SSEP监护医源性神经损伤的敏感性和特异性分别为66.7%和100%。结论 SSEP在颈椎病前路手术中监护脊髓损伤方面较敏感,对神经根损伤不敏感。     

Intraoperative spinal somatosensory evoked potential monitoring

The relationship of intraoperative monitoring of spinal cord somatosensory evoked potentials and postoperative deficit in 220 cases (121 with scoliosis, 41 with neoplasms, and 58 others) is reported. Bilateral posterior tibial nerve stimulation was used in 181 cases and unilateral median nerve stimulation in 39. Spinal cord (interspinous ligament needles), subcortical (neck surface), and cortical (scalp surface) SEP's were monitored. Seven patients had worsening of neurological function after surgery, three of whom demonstrated significant changes in SEP's monitored. In an additional four cases, there was more than a 50% decrease in amplitude of subcortical/cortical SEP's during monitoring, but no change in neurological status postoperatively. Combined monitoring of spinal cord, subcortical, and cortical SEP's enhanced the certainty of detecting spinal cord dysfunction even though there was a significant number of false-negative and false-positive results. A marked change in the SEP's indicated a high chance of developing a neurological deficit (three or 43% of seven cases), and if there was no change the chance of any neurological postoperative deficit was extremely low (four or 1.87% of 213 cases). These data justify the use of intraoperative SEP monitoring.     

Intraoperative somatosensory evoked potential monitoring in achondroplasia

Surgical airway intervention in children with achondroplastic dwarfism poses potential neurological risk secondary to the neck manipulation required for tracheal intubation and operative head positioning. This is particularly true of achondroplastic dwarfs with radiographically documented foramen magnum and spinal canal stenosis. In these children, upper extremity somatosensory evoked potential monitoring establishes the integrity of sensory conduction from peripheral nerve to cortex, providing intraoperative notification of neurologically significant cervicomedullary compression during laryngoscopy and surgical positioning.     

Intraoperative somatosensory evoked potential monitoring in scoliosis

During surgical correction of scoliosis, 63 patients had somatosensory evoked potential (SEP) monitoring of the spinal cord. Tibial nerves were unilaterally stimulated, and the potentials were recorded from the midcervical spine with surface and epidural needle electrodes. Over 85% had no significant change in their SEP and no postoperative neurologic deficits. Eleven percent had a significant change in their potential (amplitude decrease of greater than 60% and/or latency increase of greater than 2.5 msec) with no neurologic complications. One patient had a significant potential change and temporary postoperative sensory deficits did occur. One additional patient experienced postoperative neurologic complications but had no SEP change. This single false negative case, however, was clinically significant only for motor dysfunction, which is not monitored by the SEP. When changes in patient core temperature were compared to changes in SEP amplitude and latency, an intraoperative decrease in core temperature increased SEP latency and decreased amplitude, which may explain in part the false positive rate of the procedure.     

颈椎外伤前路手术中体感诱发电位监护应用

目的探讨体感诱发电位(somatosensory evoked potential,SSEP)在颈椎外伤前路手术中的作用。方法 2008-07-2015-02收治颈椎外伤前路手术患者53例,年龄16~69岁,男44例,女9例。对照组(33例)无SSEP监护,监护组20例。在麻醉诱导后摆放体位前确立SSEP基线,波幅降低50%或潜伏期延长10%为报警标准。记录SSEP报警因素、改善措施及有无医源性神经损伤。计算SSEP监护神经损伤的敏感性和特异性。结果 53例病人术后未出现新的神经损伤。SSEP监护颈椎外伤前路手术中神经损伤的敏感性和特异性为100%。结论在颈椎外伤前路手术中SSEP监护医源性神经损伤是有意义的。     

Intraoperative somatosensory evoked potential monitoring of pelvic and acetabular fractures.

The efficacy of intraoperative somatosensory evoked potential (SSEP) monitoring was evaluated in the surgical management of 82 patients with pelvic and acetabular fractures. The injuries consisted of 45 acetabular fractures, 30 pelvic ring disruptions, and seven combined injuries. Preoperative neurological deficits were recorded in 34% of the study group (29% of those with an acetabular fracture and 47% of those with a pelvic ring injury). Three patients sustained an iatrogenic sciatic nerve injury during the study period (all of which were documented in the first 40 cases). Two patients sustained an exacerbation of an existing sciatic nerve injury. In the group of pelvic fractures, hazardous parts of the exposure, reduction, and fixation were identified by the SSEP monitoring. Removal of the provocative stimulus by the surgeon led to reversal of the SSEP abnormalities, and none of this group of patients sustained an iatrogenic injury. When the intraoperative SSEP changes were noted during an acetabular fracture fixation, immediate attempts were made to relieve the excessive tension on the sciatic nerve by replacing or removing a retractor, flexing the knee, extending the hip, or dividing the femoral insertion of the gluteus maximus. None of the SSEP changes were associated with the lacerative injury to the sciatic nerve. For the method to be clinically effective in reducing the incidence of neurological deficit, even subtle changes in the SSEP tracing must be recognized immediately by the neurophysiologist so that a corresponding corrective measure can be rapidly undertaken by the surgeon to remove the offending stimulus.     

Intraoperative facet joint injury during anterior cervical discectomy and fusion: an experimental study

OBJECT: Disorders of the cervical spine can be successfully addressed by surgical intervention when the choice of such intervention takes into account the possible complications in the treated and adjacent structures. The aim of this study was to investigate the potential for intraoperative trauma in cervical zygapophysial joints and to describe possible pathological changes that may occur during cervical spine surgery. METHODS: Fifteen sheep underwent surgical intervention via an anterior cervical approach; discectomy at the C5-6 level was performed. In 10 animals, the discectomy was accompanied by titanium cage fusion. The sheep were killed immediately after completion of the operation. Radiological examination of the isolated cervical spines followed. Furthermore, the cervical spines were submitted to decalcification and incised using a microtome, and tissue sections were then studied using light microscopy. RESULTS: Radiological examination was used to assess vertebral alignment, vertebral body (VB) morphology, implant position, and endplate and facet joint gross morphology. Histological examination of the endplate and VB demonstrated degenerative lesions as well as cellular necrosis. The study of the facet joints at the treated as well as at adjacent segments (both above and below) revealed in some cases edema between the collagen fibers of the joint capsules, congestion, and microhemorrhages. Injuries were evident in animals in which the Caspar device was used. CONCLUSIONS: Histopathologically confirmed lesions occurred in facet joints while anterior cervical spine surgery was being performed in sheep. The findings were indicative of trauma and, in the case of human spine surgery, could possibly account for several postoperative complications and patient complaints.     

Intraoperative motor evoked potential monitoring: a review of 115 cases

We reviewed our experiences of intraoperative motor evoked potentials (MEPs) monitoring for 115 operations on the spine or spinal cord. We observed compound muscle action potentials from bilateral anterior tibial muscles by electrical transcranial stimulation of the motor cortex under general anesthesia induced and maintained with intravenous anesthetics (ketamine, propofol, or droperidol), fentanyl, and 50% nitrous oxide. Partial neuromuscular blockade was obtained with continuous infusion of vecuronium. MEPs were recorded bilaterally in 91 cases (79%) and laterally in 18 cases (16%). Postoperative deterioration of motor function was observed in 2 cases and amplitude of MEPs decreased more than 50% of control values in both cases. Intraoperative monitoring of MEPs might be a reliable indicator of spinal cord motor function.     

Outpatient anterior cervical discectomy and fusion.

The study reported here examined patient safety and satisfaction in 56 patients with cervical radiculopathy secondary to foraminal stenosis or a herniated disc who underwent a total of 58 outpatient anterior cervical discectomy and fusion (ACDF) procedures with iliac crest bone graft or fibular allograft. Patients were discharged 0.8 hour to 6.5 hours (mean, 2.4 hours) after surgery and received 3 home health care visits over 24 hours. Of the 45 satisfaction questionnaires that were completed, 43 (95.6%) indicated patients were satisfied or very satisfied with the surgery, and 35 (77.8%) indicated patients would have the procedure performed on an outpatient basis again. Eleven (19.6%) of the 56 patients did not respond to a satisfaction questionnaire. Outpatient ACDF has high patient satisfaction but does not compromise patient safety.     

Continuous somatosensory evoked potential monitoring during brain tumor resection. Report of four cases and review of the literature

The neurosurgical management of intrinsic brain tumors and brain metastases mandates maximum resection with preservation of functional cortex. There have been previous reports on the use of cortical somatosensory evoked potentials (SSEPs) for localization of functional cortex prior to resection. The identification of rolandic cortex with the use of intraoperative SSEP monitoring enables the neurosurgeon to tailor the surgery to achieve a greater extent of resection while minimizing the risk of morbidity. The use of continuous SSEP monitoring during resection to provide an ongoing functional assessment of somatosensory cortex has not been reported. This powerful technique is illustrated using four case examples.     

Outpatient anterior cervical discectomy and fusion

The study reported here examined patient safety and satisfaction in 56 patients with cervical radiculopathy secondary to foraminal stenosis or a herniated disc who underwent a total of 58 outpatient anterior cervical discectomy and fusion (ACDF) procedures with iliac crest bone graft or fibular allograft. Patients were discharged 0.8 hour to 6.5 hours (mean, 2.4 hours) after surgery and received 3 home health care visits over 24 hours. Of the 45 satisfaction questionnaires that were completed, 43 (95.6%) indicated patients were satisfied or very satisfied with the surgery, and 35 (77.8%) indicated patients would have the procedure performed on an outpatient basis again. Eleven (19.6%) of the 56 patients did not respond to a satisfaction questionnaire. Outpatient ACDF has high patient satisfaction but does not compromise patient safety.     

Comparison of transcranial electric motor and somatosensory evoked potential monitoring during cervical spine surgery

BACKGROUND: There has been little enthusiasm for somatosensory evoked potential monitoring in cervical spine surgery as a result, in part, of the increased risk of motor tract injury at this level, to which somatosensory monitoring may be insensitive. Transcranial electric motor evoked potential monitoring allows assessment of the motor tracts; therefore, we compared transcranial electric motor evoked potential and somatosensory evoked potential monitoring during cervical spine surgery to determine the temporal relationship between the changes in the potentials demonstrated by each type of monitoring and neurological sequelae and to identify patient-related and surgical factors associated with intraoperative neurophysiological changes. METHODS: Somatosensory evoked potential and transcranial electric motor evoked potential data recorded for 427 patients undergoing anterior or posterior cervical spine surgery between January 1999 and March 2001 were analyzed. All patients who showed substantial (at least 60%) or complete unilateral or bilateral amplitude loss, for at least ten minutes, during the transcranial electric motor evoked potential and/or somatosensory evoked potential monitoring were identified. RESULTS: Twelve of the 427 patients demonstrated substantial or complete loss of amplitude of the transcranial electric motor evoked potentials. Ten of those patients had complete reversal of the loss following prompt intraoperative intervention, whereas two awoke with a new motor deficit. Somatosensory evoked potential monitoring failed to identify any change in one of the two patients, and the change in the somatosensory evoked potentials lagged behind the change in the transcranial electric motor evoked potentials by thirty-three minutes in the other. No patient showed loss of amplitude of the somatosensory evoked potentials in the absence of changes in the transcranial electric motor evoked potentials. Transcranial electric motor evoked potential monitoring was 100% sensitive and 100% specific, whereas somatosensory evoked potential monitoring was only 25% sensitive; it was, however, 100% specific. CONCLUSIONS: Transcranial electric motor evoked potential monitoring appears to be superior to conventional somatosensory evoked potential monitoring for identifying evolving motor tract injury during cervical spine surgery. Surgeons should strongly consider using this modality when operating on patients with cervical spondylotic myelopathy in general and on those with ossification of the posterior longitudinal ligament in particular.     

Intraoperative somatosensory evoked potential monitoring of the sciatic nerve: an animal model.

Sciatic, peroneal, and tibial nerves were isolated in 18 hind limbs in 10 adult mongrel cats. A pair of needle electrodes was used to stimulate both divisions of the sciatic nerve individually at the level of the popliteal fossa. The sciatic nerve was injured by complete or partial transection, crush, and controlled compression. Motor function was correlated with intraoperative cortical somatosensory evoked potential and spinal somatosensory evoked potential tracings. We observed that significant changes in the waveforms of cortical somatosensory evoked potential and spinal somatosensory evoked potential tracings immediately precede postoperative peripheral nerve deficits, and that loss of motor function may be avoided by immediate response to significant spinal somatosensory evoked potential and cortical somatosensory evoked potential waveform changes. A complete motor palsy can be created in one division of the sciatic nerve while normal tracings are being obtained in the other division of the nerve. Stimulating both divisions may result in a spinal somatosensory-evoked potential/cortical somatosensory evoked potential tracing that masks the deficit that is present in only one nerve division.     

Microsurgical anterior approach to cervical discs review of 60 consecutive cases of discectomy without fusion

Summary During the past six years 60 patients have undergone anterior cervical microsurgical discectomy without exogenous intercorporal grafting using the operating microscope. This alternative method of treatment is a further refinement of previous techniques for the removal of cervical disc protrusions, which fulfils all the criteria of effective surgery. Discectomy provides ample exposure of the neural elements through the disc space. The visualisation of the underlying pathology is adequate through direct light and magnification of the operating microscope. A radical surgery is possible without danger of injury to the nervous structures or to the vertebral artery. The functional stability of the adjacent vertebral segment is present immediately after discectomy. A spontaneous fusion occurs in 70% of cases in six months to one year. Risks and complications of the procedure are few. Long term results are excellent, with overall benefit from surgery in 95% of cases. Comparing the results of anterior microdiscectomy without bone grafting with those of other procedures, there are no significant differences.Presented at the 7th European Congress of Neurosurgery in Brussels, September 1983.     

Variability of somatosensory evoked potential monitoring during scoliosis surgery

OBJECTIVE: Somatosensory evoked potentials (SEPs) of 65 patients undergoing scoliosis surgery were monitored by stimulation of posterior tibial nerve to observe variations in latencies and amplitudes. METHODS: Monitoring was divided into five stages: pre incision, spine exposure, instrumentation loading, deformity correction, and wound closure (stages 1-5, respectively). RESULTS: We found the latency showed significant increase and the amplitude significant reduction from stages 1 to 2. There was no significant variability from stages 2, 3, and 4, but both latency and amplitude recovered significantly from stage 4 to 5. This variability correlated with the changes in mean arterial pressure and end-tidal concentrations of isoflurane and was not dependent on the type of surgical procedure. If either 50% amplitude reduction or 10% latency prolongation of SEP compared with baseline recordings at stage 1 (pre incision) was used as warning criterion, the overall false-positive rate was 23.1%. It was significantly reduced to 7.7% if stage 2 (spine exposure) recordings were used as the baseline (P < 0.05). The false-positive rate decreased to 0% if a combined 50% amplitude reduction and 10% latency prolongation of SEP compared with the stage 2 baseline were used (P < 0.001). CONCLUSION: Based on these findings, we concluded that the time to obtain SEP baseline data should be adjusted to be post incision instead of pre incision.     

Assessment of fusion after anterior cervical discectomy

There is no established method to assess fusion in patients following anterior cervical discectomy. In this study we have made a series of measurements to detect movement between vertebrae adjacent to an operated space. The absence of movement implies structural union between adjacent vertebrae. Measurements have been made in two distinct surgical groups. Group A patients had anterior cervical discectomy with insertion of a BOP graft into the disc space. Group B patients underwent simple anterior cervical discectomy with no spacer or graft material inserted, the disc space being left empty. Details of the measurements and interpretation of results are described. In the absence of a 'gold standard' to assess bony union we propose that these measurement methods provide an objective and scientific method to assess fusion at the operated level after anterior cervical discectomy. Objective measurement of fusion will allow comparison between different surgical techniques that claim fusion as an end point. It will also become possible to study the influence of fusion on clinical outcome in different surgical populations.