U-shaped sacral fractures: surgical treatment and quality of life.

BACKGROUND: U-shaped sacral fractures are rare and highly unstable pelvic ring fractures. They are not recognised in the standard classification systems of these fractures. The fracture pattern is associated with significant neurological injury and can lead to progressive deformity and chronic pain if not diagnosed and treated properly. In recent years a variety of surgical strategies have been shown to facilitate early mobilisation and reduce early mortality as compared to non-operative strategies. Poor evidence, however, has hampered the development of a standard treatment algorithm. As for the long-term morbidity, the influence of operative treatment may be difficult to assess due to associated injury. However, evidence exists that there is a significant effect on the long-term morbidity. OBJECTIVE: To assess the injury characteristics, choice of treatment and quality of life of U-shaped sacral fractures. METHODS: Eight polytraumatised patients with U-shaped sacral fractures were identified over a 7-year period and evaluated retrospectively. They were analysed for fracture classification, associated injury, and injury severity. Clinical and Radiological results were evaluated. Neurological outcome was retrospectively classified by Gibbons' criteria. Long-term quality of life outcome was evaluated using the EuroQoL-6D questionnaire. RESULTS: The study population consists of five women and three men; with a median age of 29 years. All patients sustained severe associated injury. The Injury Severity Score ranged from 17 to 45 (median 23). The median time between trauma and definitive internal fixation was 4 days (range, 2-22 days). Definitive fixation included either percutaneous iliosacral screws (n=2), transsacral plate osteosynthesis (n=1) or triangular osteosynthesis with (n=4) or without transsacral plating (n=1). Early postoperative mobilisation and early partial weight-bearing were encouraged when possible. Follow-up ranged from 5 to 65 months (median, 36 months). Pain, mood disorders and mobility problems mainly influenced patients' present general health status. CONCLUSION: U-shaped sacral fractures present a rare and heterogeneous injury. Operative treatment depended mainly on fracture type, associated spinal fractures, and the surgeon's preference. Long-term quality of life is dominated by pain, mood disorders and moderate mobility problems.

Esophageal perforation associated with cervical spine surgery: report of two cases and review of the literature.

BACKGROUND/AIMS: Esophageal perforation after anterior cervical spine surgery is a rare complication with various clinical presentations and treatments. METHODS: Two cases of esophageal perforation after anterior cervical spine surgery are described, one occurring in the immediate postoperative period and one several years after plate stabilization of the cervical spine. RESULTS: Primary suturing of the acute perforation and diversion of the salivary flow by means of T-tube placement after delayed presentation allowed successful healing of the esophageal defects. CONCLUSION: When encountering acute dysphagia after cervical spine surgery, one should think of an esophageal perforation and install immediate further diagnostics and therapy. Treatment depends on the time of detection and size of the perforation. In early stages, with vital tissues, primary suturing is the treatment of choice. If presentation is late, it seems advisable to limit the procedure to simple drainage after removal of foreign bodies.

Clinical outcome and radiographic results after surgical treatment of post-traumatic thoracolumbar kyphosis following simple type A fractures.

The surgical management of post-traumatic thoracolumbar kyphosis remains controversial. The need for combined procedures is subject to debate, especially for post-traumatic kyphosis after simple type A fractures. The aim of this retrospective study was to evaluate radiographic findings, patient satisfaction and clinical outcome after mono-segmental surgical treatment using an anterior procedure alone (group 1, n = 10 patients) and using a one-stage combined anterior and posterior procedure (group 2, n = 15 patients) for post-traumatic thoracolumbar kyphosis after simple type A fractures. The main indication for surgery was pain. There were no statistically significant differences between the patients in the two groups concerning age, cause of injury, time interval between trauma and surgery, preoperative kyphosis and preoperative back pain score. For all these 25 patients, complete follow-up data were available for retrospective evaluation. The median follow-up was 17 years in group 1 and 8 years in group 2. Radiographic documentation and classification was made on the basis of standing antero-posterior and lateral views and computed tomographic scans. Fractures were categorized according to the Magerl classification. Kyphotic deformity was assessed on lateral radiographs using the Cobb method. Kyphosis angles were measured preoperatively, directly postoperatively, and at final follow-up. For clinical evaluation, the back pain scoring system of Greenough and Fraser was used. Patients were requested to score their status prior to trauma, preoperatively and at follow-up. The Wilcoxon test was used for statistical analysis ( P < 0.05 is significant). In all cases radiographic union was achieved. Median kyphosis in group 1 was corrected from 23 degrees preoperatively to 12 degrees postoperatively ( P < 0.01) and was 11 degrees at follow-up. Median kyphosis in group 2 was corrected from 21 degrees pre-operatively to 12 degrees postoperatively ( P < 0.01) and was 12 degrees at follow-up. The median back score in group 1 changed from 66 points before the trauma to 23 points ( P < 0.01) preoperatively and 35 points at follow-up ( P < 0.01). The median back score in group 2 changed from 67 points before the trauma to 20 points ( P < 0.01) preoperatively and 38 points at follow-up ( P < 0.01). In group 2, four patients had complaints due to annoying prominence of the dorsal instrumentation. In all these cases the dorsal instrumentation was removed. Statistical analysis in this series of ten patients with anterior spondylodesis compared with 15 patients with combined one-stage spondylodesis did not reveal objective advantages of the combined procedure as far as the outcome of radiographic correction of kyphosis or patient outcome is concerned. It is therefore concluded that in cases of post-traumatic thoracolumbar kyphosis after simple type A fractures, mono-segmental correction using an anterior procedure alone, with spondylodesis, is the surgical procedure of choice.

Results of a prospective randomised study comparing a non-invasive surgical zipper versus intracutaneous sutures for wound closure.

A prospective randomised study was undertaken to investigate the advantages and disadvantages of a non-invasive surgical zipper (Medizip) vs intracutaneous sutures skin closure in orthopaedic surgery. The study group consisted of 120 consecutive patients, 45 men and 75 women with a mean age of 47 years. The Medizip was used in 20 surgical knee wounds, 20 hip wounds and 20 orthopaedic spine wounds. The same number of patients received intracutaneous sutures. Handling, wound healing and scar formation on day 1, at 2 weeks and 6 weeks were evaluated. The average time for wound closure with the zipper was 2 min and 9.4 min when the wound was closed with intracutaneous sutures (p = 0 .01). Patients were positive in their assessment of the wound healing progress and results; they found the skin closure device agreeable to wear. The scar result was rated very good in 82% (n = 4 9) of the zipper group, and 85% (n = 5 1) in the intracutaneous group (p = 0 .67). Based on the results obtained, the non-invasive skin closure system Medizip represents a safe option in the spectrum of surgical wound treatment.

Clinical outcome and radiographic results after operative treatment of Scheuermann's disease.

The aim of this prospective study was to evaluate radiographic findings, patient satisfaction and clinical outcome, and to report complications and instrumentation failure after operative treatment of Scheuermann's disease using a combined anterior and posterior spondylodesis. The loss of sagittal plane correction after removal of the posterior instrumentation was analysed. The indication for surgery was a thoracic kyphosis greater than 60 degrees in adolescents and adults with persistent back pain, which failed to respond to conservative treatment. Thoracic kyphosis and lumbar lordosis angles were measured by the Cobb method at preselected time points and at final follow-up. Sagittal plane alignment was measured as translation. The validated Scoliosis Research Society Instrument (SRSI) questionnaire was sent to all patients at follow-up. P-values were calculated using the Wilcoxon signed rank test (P<0.05 is significant). Between October 1987 and August 1999, 23 consecutive patients underwent operative treatment. The median follow-up was 75 months (range 25-126 months). Median preoperative thoracic kyphosis was 70 degrees (range 62 degrees-78 degrees) and median preoperative lumbar lordosis was 68 degrees (range 54 degrees-84 degrees). Immediate postoperative median thoracic kyphosis was 39 degrees (range 28 degrees-54 degrees) (P<0.05) and immediate postoperative median lumbar lordosis was 49 degrees (range 35 degrees-63 degrees) (P<0.05). These significant corrections were maintained at early follow-ups conducted 1 year and 2 years postoperatively. At final follow-up, the median thoracic kyphosis had significantly increased, to 55 degrees (range 36 degrees-65 degrees) (P<0.05 relative to immediate postoperative value), and the median lumbar lordosis had increased to 57 degrees (range 44 degrees-70 degrees) (P<0.05). The late deterioration of correction in the sagittal plane was mainly caused by removal of the posterior instrumentation, and occurred despite radiographs, bone scans and thorough intra-operative explorations demonstrating solid fusions. The median SRSI score was 83 points (range 55-106). There was no significant correlation between the radiographic outcome and the SRSI score (P>0.05). Our series showed relatively fair outcome after operative treatment in Scheuermann's disease. Therefore, the indication for surgery in patients with Scheuermann's disease can be questioned.

Upper thoracic spinal fractures in trauma patients - a diagnostic pitfall.

The diagnosis of upper thoracic spinal fractures in multiple-trauma patients remains a challenge. The clinical findings are often difficult to detect, especially in the presence of other (extremity) fractures, head injuries or in patients on respiratory support. The findings of chest radiographs and plain spinal films are described in a series of 23 patients with an upper thoracic spinal fracture. Radiographs were retrospectively reviewed by an orthopaedic surgeon and a skeletal radiologist. Fractures were classified according to Magerl and type A1 and A2 compression fractures were excluded. The neurological outcome was assessed using the Frankel scale.Initially, the fracture was missed in 5 patients (22%), mainly due to concomitant life-threatening injuries. Fractures consisted of type A, B and C in one, 10 and 12 patients, respectively. The main findings were: loss of vertical height of vertebra with or without malalignment (21), widened paraspinal line (21), widened mediastinum (4) and no gross abnormalities (2). Neurological lesions were Frankel A, B, C and E in respectively 14, 1, 1 and 7 patients.Upper thoracic spinal fractures are easily missed in patients with multiple injuries. In patients with neurological symptoms CT and/or MRI is required as soon as the general condition of the patient permits this.

Comparison of two types of surgery for thoraco-lumbar burst fractures: combined anterior and posterior stabilisation vs. posterior instrumentation only.

This retrospective study compares clinical outcome following two different types of surgery for thoracolumbar burst fractures. Forty-six patients with thoracolumbar burst fractures causing encroachment of the spinal canal greater than 50% were operated on within 30 days performing either: combined anterior decompression and stabilisation and posterior stabilisation (Group 1) or posterior distraction and stabilisation using pedicle instrumentation (AO internal fixator) (Group 2). We evaluated: neurological status (Frankel Grade), spinal deformities, residual pain, and complications. The average follow-up was 6 years. There were no significant differences between the patients in both groups concerning age, sex, cause of injury and the presence of other severe injuries. Neurological dysfunction was present in 39% of all cases. Bony union occurred in all patients. Loss of reduction greater than 5 degrees and instrumentation failure occurred significantly more often in Group 2 compared to Group 1, but the kyphosis angle at late follow-up did not differ between groups, due to some degree of overcorrection initially after surgery in Group 2. The clinical outcome was similar in both groups, and all but one patient with neurological deficits improved by at least one Frankel grade. Indirect decompression of the spinal canal by posterior distraction and short-segment stabilisation with AO internal fixator is considered appropriate treatment for the majority of unstable thoracolumbar burst fractures. This is a less extensive surgical procedure than a combined anterior and posterior approach.

A comparison of myogenic motor evoked responses to electrical and magnetic transcranial stimulation during nitrous oxide/opioid anesthesia.

UNLABELLED: Transcranial motor evoked potentials (tc-MEPs) are used to monitor spinal cord integrity intraoperatively. We compared myogenic motor evoked responses with electrical and magnetic transcranial stimuli during nitrous oxide/opioid anesthesia. In 11 patients undergoing spinal surgery, anesthesia was induced with i.v. etomidate 0.3 mg/kg and sufentanil 1.5 microg/kg and was maintained with sufentanil 0.5 microg x kg(-1) x h(-1) and N2O 50% in oxygen. Muscle relaxation was kept at 25% of control with i.v. vecuronium. Electrical stimulation was accomplished with a transcranial stimulator set at maximal output (1200 V). Magnetic transcranial stimulation was accomplished with a transcranial stimulator set at maximal output (2 T). Just before skin incision, triplicate responses to single stimuli with both modes of cortical stimulation were randomly recorded from the tibialis anterior muscles. Amplitudes and latencies were compared using the Wilcoxon signed rank test. Bilateral tc-MEP responses were obtained in every patient with electrical stimulation. Magnetic stimulation evoked only unilateral responses in two patients. With electrical stimulation, the median tc-MEP amplitude was 401 microV (range 145-1145 microV), and latency was 32.8 +/- 2.3 ms. With magnetic stimulation, the tc-MEP amplitude was 287 microV (range 64-506 microV) (P < 0.05), and the latency was 34.7 +/- 2.1 ms (P < 0.05). We conclude that myogenic responses to magnetic transcranial stimulation are more sensitive to anesthetic-induced motoneural depression compared with those elicited by electrical transcranial stimulation. IMPLICATIONS: Transcranial motor evoked potentials are used to monitor spinal cord integrity intraoperatively. We compared the relative efficacy of electrical and magnetic transcranial stimuli in anesthetized patients. It seems that myogenic responses to magnetic transcranial stimulation are more sensitive to anesthetic-induced motoneural depression compared with electrical transcranial stimulation.

Influence of isoflurane on myogenic motor evoked potentials to single and multiple transcranial stimuli during nitrous oxide/opioid anesthesia.

OBJECTIVE: Transcranial motor evoked potentials (tc-MEPs) are used to monitor the spinal cord intraoperatively. Volatile anesthetics considerably depress amplitudes of tc-MEPs. This study was undertaken to determine whether multipulse stimulation might overcome this depressant effect. METHODS: In 10 patients undergoing spinal surgery, incremental doses of isoflurane were added to a nitrous oxide/opioid anesthetic regimen and maintained constant at 0.2, 0.4, and 0.6% end tidal for at least 15 minutes. tc-MEP responses to single-pulse and trains of three and five (interstimulus interval, 2 ms) transcranial electrical stimuli were recorded from the tibialis anterior muscles. RESULTS: Before the addition of isoflurane, tc-MEPs were recordable in all patients, even with single-pulse stimuli (median amplitude, 428 microV). With 0.2% end-tidal isoflurane, tc-MEPs were recordable in eight patients with single-pulse stimulation and in all patients with three and five successive stimuli. At 0.4% isoflurane, responses were recordable in only one patient using single-pulse stimuli and in all patients using three and five stimuli. With 0.6% isoflurane, tc-MEPs to trains of three and five stimuli were recordable in all patients except one. The amplitude of the responses obtained with 0.2, 0.4, and 0.6% end-tidal isoflurane was significantly smaller than that of control responses (P < 0.05). CONCLUSION: These data suggest that despite the powerful depressant effects of isoflurane on myogenic motor responses, tc-MEP monitoring during isoflurane anesthesia may be feasible, provided that multipulse stimulation paradigms are used and the concentration of isoflurane does not exceed 1 minimal anesthetic concentration unit.

[One hundred years of orthopedics in the Netherlands. IV. Spinal abnormalities]. / Honderd jaar orthopedie in Nederland. IV. Wervelkolomaandoeningen.

In recent years there has been spectacular progress in the approach to various disorders of the spinal column. Owing to improved methods of osteosynthesis there is no longer so much need for long periods of postoperative bed rest. Of all the scolioses, idiopathic scoliosis is most common. The vast majority of these cases are not clinically significant. What is seen in the remaining cases if left untreated is a progression in the curvature during growth. Progressive idiopathic scoliosis can be effectively treated using conservative methods. Screening at school is an important part of this process. If the curvature proves progressive and skeletal growth is not complete a brace can be prescribed. Use of this strategy and form of treatment can avoid progression of the curvature and development of serious deformities. This conservative therapy has markedly reduced the need for corrective surgery. Scheuermann's disease is characterized by a fixed dorsal thoracic kyphosis. Progressive Scheuermann's kyphosis can be effectively treated using a brace. The majority of fractures of the vertebral bodies can be treated conservatively. However, serious fractures normally require surgical intervention. In the industrialised Western world, low back pain is a major health problem and the foremost cause of disability and unfitness for work. Low back pain caused by degenerative disease of the spinal column should be treated using a multidisciplinary approach. The development of advanced operative techniques and osteosynthesis methods has made it possible to treat metastases of the spine surgically. The effects of this treatment on the quality of life are encouraging.

The use of ketamine or etomidate to supplement sufentanil/N2O anesthesia does not disrupt monitoring of myogenic transcranial motor evoked responses.

Intraoperative monitoring of myogenic transcranial motor evoked responses (tc-MERs) requires an anesthetic technique that minimally depresses response amplitudes. Acceptable results have been obtained during opioid/N2O anesthesia, provided that the concentration of N2O does not exceed 50%. However, this technique may necessitate supplementation with additional agents to achieve adequate depth of anesthesia. Etomidate and ketamine have been reported anecdotally or in nonsurgical situations to produce little tc-MER depression. We investigated the effects on tc-MER amplitude and latency of supplementation of a sufentanil/N2O anesthetic with etomidate or ketamine in patients undergoing spinal instrumentation. Anesthesia was induced with etomidate 0.3 mg/kg and sufentanil 1.5 mg/kg and maintained with sufentanil 0.5 mg/kg/h and N2O 50%. Muscle relaxation was kept at 25% of control. Paired transcranial electrical stimulation was performed. Each patient randomly received either ketamine (0.5 mg/kg) or etomidate (0.1 mg/kg) as a single bolus intravenously, during stable surgical conditions. Triplicate tc-MERs were recorded from the tibialis anterior muscles before and 2, 5, 10, and 15 min after drug administration. Administration of ketamine did not significantly change tc-MER amplitudes, whereas etomidate resulted in a transient amplitude depression to 72% of control (p < 0.05) at 2 min after injection. Latency remained unchanged with both drugs. In conclusion, the data suggest that both ketamine (0.5 mg/kg) and etomidate (0.1 mg/kg) can be used to supplement sufentanil/N2O anesthetic without disrupting tc-MER monitoring.

Differential effects of nitrous oxide and propofol on myogenic transcranial motor evoked responses during sufentanil anaesthesia.

We have compared the effects of 50% nitrous oxide and propofol, each administered concurrently with sufentanil, on the amplitudes and latencies of the compound muscle action potential (CMAP) response to transcranial electrical stimulation. Using a crossover design, 12 patients undergoing spinal surgery were exposed to both 50% nitrous oxide and propofol, the latter in a bolus-infusion regimen. Six patients received nitrous oxide first and six received propofol first. CMAP were recorded from the tibialis anterior muscle in response to both single and paired transcranial electrical stimuli. With single pulse stimulation, median CMAP amplitude was significantly greater during administration of nitrous oxide than propofol (nitrous oxide 335 (10th-90th percentiles 35-849) microV; propofol 36 (0-251) microV) (P < 0.01). With paired stimulation, there was no significant difference in CMAP amplitude during the two regimens (nitrous oxide 1031 (296-1939) microV; propofol 655 (0-1867) microV). The results indicate that propofol caused more depression of transcranial electrical motor evoked responses than 50% nitrous oxide but that the difference was probably clinically unimportant when a paired stimulation paradigm was used.

The use of a circumferential cathode improves amplitude of intraoperative electrical transcranial myogenic motor evoked responses.

Measurement of motor evoked responses to transcranial electrical stimulation (tc-MER) is a technique for intraoperative monitoring of motor pathways. Since most anesthetics significantly reduce motoneuronal excitability, optimal stimulation paradigms should be sought. We compared the efficiency of stimulus delivery using two different configurations of the cathode component of the stimulating electrode pair (circumferential: Fz, F3, F4, A1, and A2 versus a single cathode at Fz). The anode was positioned at Cz with both cathode configurations. Fourteen neurologically normal patients undergoing spinal surgery were anesthetized with sufentanil-N2O-ketamine. Partial neuromuscular blockade (single twitch height 25%) was maintained with vecuronium. Compound action potentials to transcranial stimulation with both cathode configurations were recorded from the tibialis anterior muscle. All recordings were completed before spinal manipulation. The median amplitude response using the Fz cathode configuration was 256 microV (10th-90th percentiles: 50-641 microV). With the circumferential cathode configuration, tc-MER amplitude increased to 281 (87-1479) microV (P < 0.01). There was no significant difference in onset latency between electrode configurations. The observed tc-MER amplitude augmentation with the use of a circumferential cathode might allow tc-MER monitoring in those patients who do not have sufficiently reproducible responses when a single cathode is used. A possible explanation is that the circumferential cathode alters the direction of the electrical currents in the cortex, resulting in more efficient depolarization of cortical motor neurons.

Improved amplitude of myogenic motor evoked responses after paired transcranial electrical stimulation during sufentanil/nitrous oxide anesthesia.

BACKGROUND: Measurement of motor evoked responses to transcranial stimulation (tc-MER) is a technique for intraoperative monitoring of motor pathways in the brain and spinal cord. However, clinical application of tc-MER monitoring is hampered because most anesthetic techniques severely depress the amplitude of motor evoked responses. Because paired electrical stimuli increase tc-MER responses in awake subjects, we examined their effects in anesthetized patients undergoing surgery. METHODS. Eleven patients whose neurologic condition was normal and who were undergoing spinal or aortic surgery were anesthetized with sufentanil-N20-ketamine. Partial neuromuscular blockade (single-twitch height 25% of baseline) was maintained with vecuronium. Single and paired electrical stimuli were delivered to the scalp, and compound action potentials were recorded from the tibialis anterior muscle. The amplitude and latency of the tc-MERs were measured as the interval between paired stimuli was varied between 0 (single stimulus) and 10 ms. All recordings were completed before spinal manipulation or aortic clamping. RESULTS: Median amplitude of the tc-MER after a single stimulus was 106 microV (10th-90th percentiles: 23-1,042 microV), and the latency to onset was 33.2 +/- 1.4 ms (SD). With paired stimuli (interstimulus interval 2-3 ms), tc-MER amplitudes increased to 285 (79-1,605) microV, or 269% of the single-pulse response (P < 0.01). Reproducibility of individual responses increased with paired stimulation. Onset latency decreased to 31.4 +/- 3.2 ms (P < 0.05). Maximum amplitude augmentation was observed with interstimulus intervals between 2 and 5 ms and in patients with low-amplitude responses after single-pulse stimulation. CONCLUSIONS: Application of paired transcranial electrical stimuli increases amplitudes and reproducibility of tc-MERs during anesthetic-induced depression of the motor system. The effect may represent temporal summation of stimulation at cortical or spinal sites. The results of this study warrant further clinical evaluation of paired transcranial stimulation.

Neurologic injury after insertion of laminar hooks during Cotrel-Dubousset instrumentation.

BACKGROUND DATA: Although the use of Cotrel-Dubousset (CD) instrumentation has improved results of operative treatment of scoliotic deformities, this technique may be associated with increased risk of neurologic injury. CASE HISTORIES: Two cases of neurologic complications immediately after insertion of lumbar laminar hooks during CD instrumentation for correction of scoliosis are reported. METHODS: Between 1986 and 1992, the authors performed 220 CD instrumentations for various spinal deformities. All patients were monitored with posterior tibial nerve somatosensory cortical evoked potentials (PTN-SSEPs). CONCLUSION: These cases demonstrate that caution should be exercised during introduction of laminar hooks on the concave side during CD instrumentation for scoliotic deformities. Continuous neurophysiologic monitoring of spinal cord conduction may aid in early detection of local compression at the spinal cord or cauda equina level.

Cellular hemangioma and angioblastoma of the spine, originally classified as hemangioendothelioma. A confusing diagnosis.

STUDY DESIGN: The authors report two cases of vascular tumors of the spine, classified originally as benign and malignant hemangioendothelioma, and after revision, as cellular hemangioma and angioblastomatosis, respectively. OBJECTIVES: Problems in interpretation of the confusing term hemangioendothelioma and treatment modalities for vascular tumors of the spine are discussed. SUMMARY OF BACKGROUND DATA: Hemangioendothelioma is a confusing term and is often used to cover bewilderment at the biological behavior of a vascular tumor. Its spectrum ranges, depending the references used, from benign to malignant and can mistakenly include benign lesions like cellular hemangioma and angioblastoma (solitary and multicentric). METHODS: Of two patients with a cellular tumor of the spine, the clinicopathologic data and modes of treatment are reviewed. The relevant literature is discussed. RESULTS: In the first case, the diagnosis of benign cellular hemangioendothelioma was changed to cellular hemangioma. In the second case, the original diagnosis of malignant hemangioendothelioma with metastasis to liver and lungs was changed to angioblastomatosis, most probably benign. In both cases, a correct interpretation of the initial diagnosis or proper diagnosis would have influenced the mode of treatment. CONCLUSION: Avoid the confusing term hemangioendothelioma. If a vascular lesion is benign, it should be classified as a variant of hemangioma. If malignant as angiosarcoma, use a separate category, in which lesions like angioblastoma and angioblastomatosis can be put until their nature has been clarified.

Variability of somatosensory cortical evoked potentials during spinal surgery. Effects of anesthetic technique and high-pass digital filtering.

The effects of anesthetic technique (nitrous oxide or propofol) and high-pass digital filtering on within-patient variability of posterior tibial nerve somatosensory cortical evoked potentials (PTN-SCEP) were compared prospectively in two groups of 20 patients undergoing spinal surgery. Average P1N1 amplitude was significantly higher and P1N1 amplitude variability lower during propofol/alfentanil anesthesia than during nitrous oxide/alfentanil anesthesia. Off-line 30-Hz high-pass digital filtering significantly reduced P1N1 amplitude variability without decreasing P1N1 amplitude. In 93 patients studied retrospectively, a significant negative logarithmic correlation (r = -0.77) was observed between P1N1 amplitude and P1N1 amplitude variability. This study shows the importance of maintaining the highest possible PTN-SCEP amplitudes during spinal surgery. Propofol/opioid anesthesia may be an alternative anesthetic technique to nitrous oxide/opioid anesthesia during spinal cord function monitoring.

Anterior decompression and stabilization of thoracolumbar burst fractures using the Slot-Zielke-device.

A retrospective study was performed on 62 patients treated for thoracolumbar burst fractures. The Fracture Study Protocol of the Scoliosis Research Society was used for data collection. The first group consisted of 29 patients, treated between July 1983 and November 1986 with an one-stage operation consisting of anterior decompression by subtotal vertebrectomy, reduction and stabilization with the Slot-Zielke device. The mean follow-up was 3.1 years. The second group consisted of 33 patients, who were treated between November 1986 and November 1988. In this second group treatment was performed by an anterior decompression by subtotal vertebrectomy, reduction and stabilization with the Slot-Zielke-device, in the same session followed by an additional posterior spondylodesis and instrumentation with the Zielke D.K.S.-system or by the Cotrel-Dubousset compression-rod system. Mean follow-up of this second group was 1.7 years. In all patients bony union occurred. Loss of reduction of more than 5 degrees occurred in 41% of the patients of the first group, but in only one patient (3%) of the second group. In both groups most patients with incomplete neurologic lesions improved postoperatively and were upgraded one or two steps on the Frankel-scale. No patient showed neurologic deterioration after surgery. In both groups a high percentage of patients were painfree at follow-up. The complication rate in both groups was low, despite the rather difficult anterior approach. Because of the high rate of loss of reduction in the first group of 29 patients and the low degree of flexion-bending loading and torsional stability in biomechanical evaluation in vitro of the Slot-Zielke device on human cadaver spine, an additional posterior stabilization of the spine after an anterior approach for anterior- and middle-column fractures should be considered.

Anterior decompression and stabilization of thoracolumbar burst fractures by the use of the Slot-Zielke device.

Between July 1983 and November 1986, 29 patients with thoracolumbar burst fractures underwent a one-stage operation consisting of anterior decompression by subtotal vertebrectomy, reduction, and stabilization with the Slot-Zielke device. The mean follow-up was 3.1 years. Most patients with incomplete neurologic lesions showed postoperative improvement and were upgraded one or two steps in the Frankel scale. No patient showed neurologic deterioration after surgery. In all patients, bony union occurred. Loss of reduction of more than 5 degrees occurred in 41% of the patients. Because of this high rate of loss of reduction in patients and the low degree of flexion-bending loading and torsional stability in biomechanical evaluation in vitro of the Slot-Zielke device on human cadaveric spines, an additional posterior stabilization of the spine after an anterior approach for anterior- and middle-column fractures should be considered.