Tao Li

Posterior vertebral column resection for correction of rigid spinal deformity curves greater than 100

OBJECT The surgical treatment of severe and rigid spinal deformities poses difficulties and dangers. In this article, the authors summarize their surgical techniques and evaluate patient outcomes after performing posterior vertebral column resection (PVCR) for the correction of spinal deformities with curves greater than 100°, and investigate the crucial points to ensure neurological safety during this challenging procedure. METHODS The authors retrospectively reviewed their experience with 28 patients with extremely severe (Cobb angles in the coronal or sagittal plane > 100°) and rigid thoracic or thoracolumbar spine deformities who underwent PVCR. The average patient age was 20.2 years and all patients underwent a minimum follow-up of 24 months (range 24-60 months). Patients were divided into groups according to their morphological classification as follows: kyphosis alone (Group A, 6 patients with a mean Cobb angle of 109.0° [range 105°-120°]); kyphoscoliosis with coronal plane curves notably greater than sagittal plane curves (Group B, 14 patients with mean scoliotic curves of 116.6° [range 102°-170°] and kyphotic curves of 77.7° [range 42°-160°]); and kyphoscoliosis with sagittal curves notably greater than coronal plane curves (Group C, 8 patients with a mean coronal curve of 85.4° [range 65°-110°] and a mean sagittal curve of 117.6° [range 102°-155°]). RESULTS A total of 36 vertebrae were removed in 28 patients who had a severe rigid spinal deformity, and the mean fusion extent was 13.3 vertebrae (range 7-17 vertebrae). The mean operating time was 620 minutes (range 320-920 minutes) with an average operative blood loss of 6,680 ml (range 3,000-24,000 ml). The overall final correction rate of scoliosis was 59.0%, and average postoperative kyphotic Cobb angles ranged from 30.4° to 95.9°. In Group A the mean preoperative sagittal angle of 109.0° was corrected to a mean postoperative angle of 32.0°. In the Group B kyphoscoliotic patients, the correction rate in the coronal plane was 58.6%; the Cobb angle in the sagittal plane was corrected from a mean of 77.7° preoperatively to 25.1° postoperatively; in Group C, the correction rate in the coronal plane was 58.5%, and the mean sagittal angle was reduced from a mean of 117.6° preoperatively to 39.0°. Of the 28 patients who underwent PVCR, 46 complications were observed in 18 patients intra- and postoperatively. There were 5 neurological complications including 1 case of late-onset paralysis and 4 cases of thoracic nerve root pain, all of which resolved during the early follow-up period. Nonneurological complications occurred more often in kyphoscoliotic patients (41 complications). The mean follow-up of all patients was 33.7 months (range 24-60 months). CONCLUSIONS Posterior vertebral column resection was effective in correcting severe rigid spinal deformity, although the procedure was technically demanding, exhaustingly lengthy, and was associated with a variety of complications. The PVCR technique created a space for spinal correction and spinal cord tension adjustment and the correction could be performed under direct inspection and by palpation of the tension in the spinal cord through the space. Therefore, in terms of the spinal cord, the deformity correction process involved in the PVCR procedure is relatively safe.

Preliminary investigation of high-dose tranexamic acid for controlling intraoperative blood loss in patients undergoing spine correction surgery.

BACKGROUND CONTEXT With a significant increase in the number and complexity of spinal deformity corrective surgeries, blood loss, often requiring massive intraoperative transfusions, becomes a major limiting factor during surgery. This scenario is particularly during posterior vertebral column resection (PVCR), where extensive intraoperative blood loss may pose a major risk to the patient, preventing smooth execution of the procedure. Tranexamic Acid (TXA) has been used in cardiac and orthopedic surgeries, including major spinal surgeries, to reduce blood loss and transfusion requirements for decades. PURPOSE To assess the efficacy and safety of high doses of TXA in posterior spinal deformity corrective surgery, including PVCR procedures. STUDY DESIGN A retrospective study from a single institution. PATIENT SAMPLE Fifty-nine patients (age range 7 to 46 years old) with spinal deformities undergoing spinal corrective surgeries were included. The patients were divided into two groups: the TXA group (total of 26 patients, including 8 PVCR patients) and the control group (total of 33 patients, including 9 PVCR patients). OUTCOME MEASURES The analyzed outcome measures included estimated intraoperative blood loss, real blood loss (RBL; blood loss/blood volume×100%), blood transfusion requirements, coagulation parameters, complete blood count, liver function, and renal function. Lower limb vein thrombus, symptomatic pulmonary embolism, symptomatic myocardial infarction, seizures, and acute renal failure were also recorded. METHODS Before skin incision, the patients in the TXA group received an intravenous loading dose of 100 mg/Kg over a 20-minute period, followed by a maintenance infusion of 10 mg/Kg/h until skin closure was completed. The patients in the control group received saline infusion of a similar volume. Statistics included estimated intraoperative blood loss, RBL, blood transfusion requirements, coagulation parameters, complete blood count, liver function, and renal function. All patients in this study were also carefully monitored for consciousness level, breathing status, chest tightness or pain, and urine output after surgery. These were done to detect the presence or absence of pulmonary embolism, myocardial infarction, seizures, and acute renal failure. Patients treated with TXA were examined via vascular ultrasound before and after surgery. RESULTS There were no significant differences in the demographic or surgical traits between the two groups. The blood loss of the patients in the TXA group was 2,441±1,666 mL, whereas that of the control group patients was 4,789±4,719 mL. The difference was statistically significant (p<.05). The average RBL of the patients in the TXA group was 80.6%±49.6% versus 160.8%±163.1% in the control group (p<.05). The blood transfusion requirements for the patients in the TXA group were significantly less than that in the control group (p<.05). Blood loss, RBL, and blood transfusion requirements were all significantly lower in the TXA group, compared with the control group among both PVCR patients and non-PVCR patients. In the TXA group, there was an average of 57.4% reduced blood loss in patients who received PVCR and 39.8% in patients not receiving PVCR. There were no differences in liver and renal functions between the TXA and control groups. There was no lower limb vein thrombus, symptomatic myocardial infarction, symptomatic pulmonary embolism, seizures, or acute renal failure reported in the TXA group. CONCLUSIONS In our study, high doses of TXA have been shown to effectively control blood loss and reduce the transfusion requirement. This effect was more apparent in patients receiving PVCR. No adverse drug reaction was recorded in the study. In the future, prospective randomized controlled trials to validate our results will be necessary. Future studies conducted on older patient cohort may also be necessary to confirm the safety of extending the use of TXA to the older patients.

Changes in CSF flow after one-stage posterior vertebral column resection in scoliosis patients with syringomyelia and Chiari malformation type I.

OBJECT Phase contrast-cine MRI (PC-cine MRI) studies in patients with syringomyelia and Chiari malformation Type I (CM-I) have demonstrated abnormal CSF flow across the foramen magnum, which can revert to normal after craniocervical decompression with syrinx shrinkage. In order to investigate the mechanisms leading to postoperative syringomyelia shrinkage, the authors studied the hydrodynamic changes of CSF flow in the craniocervical junction and spinal canal in patients with scoliosis associated with syringomyelia after one-stage deformity correction by posterior vertebral column resection. METHODS Preoperative and postoperative CSF flow dynamics at the levels of the foramen magnum, C-7, T-7 (or apex), and L-1 were assessed by electrocardiogram-synchronized cardiac-gated PC-cine MRI in 8 adolescent patients suffering from severe scoliosis with syringomyelia and CM-I (scoliosis group) and undergoing posterior vertebral column resection. An additional 8 patients with syringomyelia and CM-I without spinal deformity (syrinx group) and 8 healthy volunteers (control group) were also enrolled. Mean values were obtained for the following parameters: the duration of a CSF cycle, the duration of caudad CSF flow (CSF downflow [DF]) and cephalad CSF flow (CSF upflow [UF]), the ratio of DF duration to CSF cycle duration (DF%), and the ratio of UF duration to CSF cycle duration (UF%). The ratio of the stationary phase (SP) duration to CSF cycle duration was calculated (SP%). The maximum downflow velocities (VD max) and maximum upflow velocities (VU max) were measured. SPSS (version 14.0) was used for all statistical analysis. RESULTS Patients in the scoliosis group underwent one-stage posterior vertebral column resection for deformity correction without suboccipital decompression. The mean preoperative coronal Cobb angle was 102.4° (range 76°-138°). The mean postoperative Cobb angle was 41.7° (range 12°-75°), with an average correction rate of 59.3%. During the follow-up, 1 patient with hypermyotonia experienced a significant decrease of muscle tension and 1 patient with reduced anal sphincter tone manifested recovery. A total of 5 patients demonstrated a significant decrease (> 30%) in syrinx size. With respect to changes in CSF flow dynamics, the syrinx group was characterized by slower and shorter downflow than the control group, and the difference was more significant at the foramen magnum and C-7 levels. In patients with scoliosis, CSF downflow at the foramen magnum level was significantly restricted, and a prolonged stationary phase indicated increased obstruction of CSF flow. After posterior vertebral column resection, the peak velocity of CSF flow at the foramen magnum increased, and the downflow phase duration was markedly prolonged. The parameters showed a return to almost normal CSF dynamics at the craniocervical region, and this improvement was maintained for 6-12 months of follow-up. CONCLUSIONS There were distinct abnormalities of CSF flow at the craniocervical junction in patients with syringomyelia. Abnormal dynamics of downflow could be aggravated by associated severe spinal deformity and improved by correction via posterior vertebral column resection.

Perioperative Major Non-neurological Complications in 105 Patients Undergoing Posterior Vertebral Column Resection Procedures for Severe Rigid Deformities.

Study Design. Retrospective study. Objective. To analyze the perioperative major non-neurological complications (MNNCs) in posterior vertebral column resection (PVCR) procedures for severe rigid deformities and to identify the factors that may increase the risk. Summary of Background Data. Although surgeons constantly attempted to increase the corrective efficacy and neurological safety after PVCR, there are still significant risks of major and potentially life-threatening complications. Methods. A total of 105 consecutive patients with severe rigid deformity who underwent 1-stage PVCR at a single center from 2004 to 2013 were reviewed. The demographic data, medical and surgical histories, perioperative and final follow-up radiographical measurements, and prevalence of perioperative MNNCs were reviewed. Results. The mean age of patients at the time of surgery was 18.9 years (range: 10–45 yr). The major curve of scoliosis was 108.9 ± 25.5 preoperatively and 37.2 ± 16.8 at the final follow-up, and segmental kyphosis was from 89.8 ± 31.1 to 30.4 ± 15.3. There were 31 MNNCs in 24 patients: 16 respiratory complications in 13 patients, 9 cardiovascular adverse events in 7 cases, 1 malignant hyperthermia, and 1 optic deficit. There were 3 patients with wound infection, and 1 of them had to undergo partial removal of the implant for infection control. One patient with neurofibromatosis died 1 day after operation. Factors that showed no relationships with an increased prevalence of MNNCs were age, sex, presence of cardiac disease or neural axis malformation, and both sagittal and coronal correction rate. Patients with T6 and upper resected level, undergoing PVCR at the early period, showed a trend toward more MNNCs encountered. Moreover, nonidiopathic deformity, large scoliotic curve greater than 150°, percent predicated forced vital capacity and forced expiratory volume in 1 second (FEV1.0) less than 40%, and estimated blood loss volume more than 5000 mL were identified as risk factors associated with MNNCs. Conclusion. Patients who had undergone PVCR experienced expected higher rate of MNNCs, with an overall prevalence of 22.9%. When considering PVCR, it is important to recognize the significantly higher inherent risks and provide appropriate preoperative counseling on the risks and benefits of surgery. Level of Evidence: 3

Proper Responding Strategies to Neuromonitoring Alerts During Correction Step in Posterior Vertebral Column Resection Patients With Severe Rigid Deformities Can Reduce Postoperative Neurologic Deficits

Study Design. Retrospective study. Objective. To analyze the intraoperative neuromonitoring (IOM) changes in posterior vertebral column resection (PVCR) for severe rigid deformity patients, and describe our stepwise responding strategies. Summary of Background Data. Obvious neurological deficit risk accompanied with PVCR correction has been emphasized repeatedly. Methods. The records of 46 patients who underwent PVCR achieved IOM were reviewed. IOM alerts triggered responding protocols: (1) exchange the convex corrective rod to concave stabilizing rod, (2) appropriate compression for spinal shortening, (3) reversed in situ rod bending, (4) translation technique and unisegmental derotation, (5) adjacent segmental resection. Results. The overall scoliotic correction rate was 65.4% (from 112 ± 28.6 to 39 ± 13.4) and segmental kyphotic correction rate was 64.2% (from 101 ± 37.3 to 36 ± 19.2). During correction step, somatosensory-evoked potential warning (3) and somatosensory-evoked potential/transcranial motor-evoked potential warning (8) were detected in 11 patients (23.9%). Probable cause identification including rule out IOM technical factors, residual impingement, and if there was unstable spinal column (1), spinal cord excessive tension on concave side (3), and the excessive opposite spinal displacement between two aspects of resected area (7). After rod change (1), compression (2), bending (3), derotation (3), and adjacent resection (2), all IOM changes went to under warning criteria. All 11 patients revealed neurologically intact postoperatively. There was no difference of correction rate between IOMs alert or not. However, adult, extremely severe or sharp angular curves tend to be more common in IOM alert patients. Conclusion. As three-dimensional spinal column divided and relinked in PVCR, and the correction maneuvers were restricted on single dimension, inevitably resulted in spinal cord tension changes and spinal column opposite displacement. To timely identify them, prompt interventions should be performed, and even enlarge the resected area to reduce the abrupt turning tendency of the spinal cord. Level of Evidence: 5