Surgical Correction Of Spinal Deformity Research Articles

Planning the Surgical Correction of Spinal Deformities: Toward the Identification of the Biomechanical Principles by Means of Numerical Simulation.

In decades of technical developments after the first surgical corrections of spinal deformities, the set of devices, techniques, and tools available to the surgeons has widened dramatically. Nevertheless, the rate of complications due to mechanical failure of the fixation or the instrumentation remains rather high. Indeed, basic and clinical research about the principles of deformity correction and the optimal surgical strategies (i.e., the choice of the fusion length, the most appropriate instrumentation, and the degree of tolerable correction) did not progress as much as the implantable devices and the surgical techniques. In this work, a software approach for the biomechanical simulation of the correction of patient-specific spinal deformities aimed to the identification of its biomechanical principles is presented. The method is based on three-dimensional reconstructions of the spinal anatomy obtained from biplanar radiographic images. A user-friendly graphical user interface allows for the planning of the desired deformity correction and to simulate the implantation of pedicle screws. Robust meshing of the instrumented spine is provided by using consolidated computational geometry and meshing libraries. Based on a finite element simulation, the program is able to predict the loads and stresses acting in the instrumentation as well as those in the biological tissues. A simple test case (reduction of a low-grade spondylolisthesis at L3–L4) was simulated as a proof of concept, and showed plausible results. Despite the numerous limitations of this approach which will be addressed in future implementations, the preliminary outcome is promising and encourages a wide effort toward its refinement.

Coronal Spinal Balance in Adult Spine Deformity Patients With Long Spinal Fusions

This study was a retrospective one. The objective of the study was to analyze the causes, prevalence of, and risk factors for coronal decompensation in long adult lumbar spinal instrumentation and fusion (from thoracic or upper lumbar spine) to L5 or S1. Coronal and sagittal decompensation after long fusions for spinal deformities can affect outcomes negatively. There is no study reporting the natural history of coronal spinal balance after long spinal fusions. A single-center retrospective review of data from 54 patients with spinal deformity was performed. Inclusion criteria were patients over 18 years with long fusions (>4 segments) to L5 or the pelvis who had full spine standing radiographs before surgery and up to 2-5 years postoperatively. Radiographic data included C7PL, magnitude of scoliotic curve, shoulder or pelvic asymmetry in the coronal plane, thoracic kyphosis, lumbar lordosis, and pelvic parameters (pelvic incidence, pelvic tilt, sacral slope). Coronal imbalance (CI) was considered if the C7PL was >4 cm lateral to the central sacral line, and sagittal imbalance (SI) was considered when the C7 plumbline was >4 cm anterior to the middle of the upper sacral plate. Paired t test, χ test, and repeated measures regression analysis using demographic data (age, sex, body mass index), operative (previous fusion, posterior only or anteroposterior fusion, iliac fixation or not, decompression or not, osteotomy or not) and postoperative (complications, use of bracing) data, and radiographic parameters (including SI) were performed. Patients showing CI equaled 11 (19.3%) preoperatively, remained 11 (19.3%) (4 of whom were new patients with CI) at 6 weeks postoperatively, and increased (P<0.001) to 18 (31.6%) (8 of them without initial CI) at 2-5 years follow-up. However, in terms of numeric distance of C7PL from the midsacrum, there was no statistically significant change (P>0.05) from preoperative to last follow-up. SI showed significant improvement (P<0.05) from preoperative to 6 weeks postoperative and no statistical significant change (P>0.05) from 6 weeks to 2-5 years postoperatively. Repeated measures regression analysis showed that the presence of osteoporosis and the combination of anterior approach surgery with a history of previous surgery were significant (P<0.05) factors predictive of changes in coronal balance. After surgical correction of spinal deformities, coronal spinal decompensation appears in an increased number of patients at last follow-up postoperatively but without significant differences in coronal plane C7PL during the postoperative period. Attention should be paid to patients with osteoporosis and those with a combination of previous same site posterior spine surgery and new anterior approach surgery for changes of coronal balance postoperatively.

Influence of vertebral column distraction on spinal cord volume: an experimental study in a goat model.

Spinal cord injury may be related to excessive distraction of the spinal cord during surgical correction of spinal deformities by vertebral column resection. This study aimed to investigate how vertebral column distraction influences spinal cord volume to establish the safe range in a goat model. A vertebral column resection was performed on the tenth thoracic vertebra of 11 goats. The spinal cord was distracted until the somatosensory evoked potential signals were decreased to 50 % from baseline amplitude or were delayed by 10 % of the baseline peak latency. The osteotomy segment was stabilized with a PEEK mesh cage filled with bone graft, and the pedicle screws on the rods were then tightened in this position. Spinal cord volume was calculated using Mimics software, and T10 height, disk height, osteotomy segment height, and spinal segment height were measured using the MRI image workstation. Three goats were excluded, and data obtained from the eight remaining goats were analyzed. The safe limit of distraction distance was 11.8 ± 3.65 mm, and the distraction distance was strongly correlated with the difference between the pre- and postoperative measurements (d value) of spinal cord volume per 1 mm of osteotomy segment height (r = -0.952, p < 0.001), but was not correlated with T10 body height (r = 0.16, p = 0.71), spinal segment height (r = 0.29, p = 0.49), disk height (r = -0.12, p = 0.98), or the d value (pre-post) of spinal cord volume per 1 mm of spinal segment height (r = 0.45, p = 0.26). The mean d value (pre-post) of spinal cord volume per 1 mm of osteotomy segment height was 10.05 ± 0.02 mm(3) (range 10.02-10.08 mm(3)). The maximum change in spinal cord volume per 1-mm change in height was in the osteotomy segment, and its safe limit was 10.05 ± 0.02 mm(3). The safe limit of spinal cord distraction can be calculated using the spinal cord volume per unit 1-mm change in height.

Motor Evoked Potentials for Femoral Nerve Protection in Transpsoas Lateral Access Surgery of the Spine

ABSTRACTDetecting potential intraoperative injuries to the femoral nerve should be the main goal of neuromonitoring of lateral lumber interbody fusion (LLIF) procedures. We propose a theory and technique to utilize motor evoked potentials (MEPs) to protect the femoral nerve (a peripheral nerve), which is at risk in LLIF procedures. MEPs have been advocated and widely used for monitoring spinal cord function during surgical correction of spinal deformity and surgery of the cervical and thoracic spine, but have had limited acceptance for use in lumbar procedures. This is due to the theoretical possibility that MEP recordings may not be sensitive in detecting an injury to a single nerve root considering there is overlapping muscle innervation of adjacent root levels. However, in LLIF procedures, the surgeon is more likely to encounter lumbar plexus elements than nerve roots. Within the substance of the psoas muscle, the L2, L3, and L4 nerve roots combine in the lumbar plexus to form the trunk of the femoral nerve. At the point where the nerve roots become the trunk of the femoral nerve, there is no longer any alternative overlapping innervation to the quadriceps muscles. Insult to the fully formed femoral nerve, which completely blocks conduction in motor axons, should theoretically abolish all MEP responses to the quadriceps muscles. On multiple occasions over the past year, our neuro-monitoring groups have observed significantly degraded amplitudes of the femoral motor and/or sensory evoked potentials limited to only the surgical side. Most of these degraded response amplitudes rapidly returned to baseline values with a surgical intervention (i.e., prompt removal of surgical retraction).

Lumbar nerve root mapping by the spinal cord monitoring in adult spinal deformity surgery

Objective When we perform surgical correction for spinal deformity with degenerative changes, nerve root impingement, traction, or nerve root injury could be occurred. Electromyographic (EMG) monitoring provides a real-time measure of impending spinal nerve root injury during instrumented posterior lumbar fusion. However, the utility of intraoperative EMG monitoring is still questionable because of large variance in muscle domination, morphological abnormality and the abnormal EMG signal from a nearby muscle. The aim of this study was identified clinical mapping of lumbar nerve root motor domination under EMG monitoring in the patients who had normal root morphology.

Range of instrumentation and complications in the surgical treatment of spinal deformity in patients with Parkinson's Disease

Purpose Parkinson’s Disease (PD) patients are a high-risk population in adult spinal surgery and there is no general consensus regarding the surgical correction of spinal deformity in these patients. We perform long fusion for PD spinal deformity in our institution and this study is a retrospective assessment of the radiological and clinical outcomes of posterior spinal fusion with instrumentation for spinal deformity in Parkinson’s disease (PD).

Pulmonary function following adult spinal deformity surgery: minimum two-year follow-up.

The literature regarding pulmonary function in adult patients with spinal deformity is limited, and the effect of spinal deformity surgery on pulmonary function has not been clearly understood. We hypothesized that adult patients with spinal deformity who had preoperative pulmonary impairment (a percent-predicted value of <65% forced expiratory volume in one second [FEV1] as measured by pulmonary function test) or who were undergoing revision surgery may be at risk for exacerbated decline in pulmonary function. Pulmonary function test results were prospectively collected for 164 adult patients with spinal deformity (mean age, 45.9 years) who underwent surgical treatment at a single institution and were followed for a minimum of two years (mean, 2.8 years). One hundred (61%) of the patients underwent primary surgery, and sixty-four (39%) of the patients had revision surgery. For the majority of patients (77%), a posterior-only surgical approach was used. Radiographs for 154 patients were analyzed for major thoracic and sagittal T5-T12 curve magnitude/correction. For all patients, we noted a significant change in major thoracic Cobb angle, from a mean of 47.4° to 24.9°(p < 0.001), and in sagittal Cobb angle, from a mean of 35.5° to 30.0°(p < 0.001), as well as a significant decline in absolute and percent-predicted pulmonary function values, with percent-predicted FEV1 and percent-predicted forced vital capacity (FVC) decreasing 5.3% (p < 0.001) and 5.7% (p < 0.001), respectively. A clinically significant decline (a decline of ≥10% in percent-predicted FEV1) was observed in 27% of the patients. The number of patients with pulmonary impairment increased nonsignificantly from seventeen (10%) preoperatively to twenty-three (14%) after surgery (p = 0.31). Patients with preoperative pulmonary impairment demonstrated a significant improvement in absolute and percent-predicted FEV1 after surgery compared with those without preoperative impairment (2.7% compared with -6.2%; p < 0.001). Patients who underwent revision surgery did not differ from primary surgery patients in terms of postoperative percent-predicted results. However, revision surgery more frequently resulted in a significant decline in pulmonary function (twenty-three patients [36%] compared with twenty-two [22%]; p = 0.05). There was no difference in pulmonary function when comparing surgical approaches (anterior/combined anterior-posterior or posterior-only) or when comparing results by upper-instrumented vertebra (UIV). We found a significant decline in absolute and percent-predicted results of pulmonary function tests following surgical correction for spinal deformity in adults.

The Changes of SEP/MEP following Ligating Spinal Cord Segmental Vessels in Applying Posterior Vertebral Column Resection (PVCR) to Treat Severe Rigid Spinal Deformity

Intraoperative monitoring (IOM) is well known to improve the security of the spinal cord in spinal surgery, especially in the surgical correction of spinal deformity. In applying posterior vertebral column resection (PVCR) to treat severe spinal deformity, ligating several spinal cord segmental vessels is unavoidable for exposure as well as vertebral resection, and this process threatens the safety of spinal cord. Only a few studies are related to the potential effects to spinal cord following ligating segmental vessels.

Augmentation of motor evoked potentials using multi-train transcranial electrical stimulation in intraoperative neurophysiologic monitoring during spinal surgery

Transcranial motor evoked potentials (TcMEPs) are widely used to monitor motor function during spinal surgery. Improvements in transcranial stimulation techniques and general anesthesia have made it possible to record reliable and reproducible potentials. However, TcMEPs are much smaller in amplitude compared with compound muscle action potentials (CMAPs) evoked by maximal peripheral nerve stimulation. In this study, multi-train transcranial electrical stimulation (mt-TES) was introduced to enhance TcMEPs, and the optimal setting of mt-TES was investigated. In 30 patients undergoing surgical correction of spinal deformities (4 males and 26 females with normal motor status; age range 11-75years), TcMEPs from the abductor hallucis (AH) and quadriceps femoris (QF) were analyzed. A multipulse (train) stimulus with an individual pulse width of 0.5ms and an inter-pulse interval of 2ms was delivered repeatedly (2-7 times) at different rates (2, 5, and 10Hz). TcMEP amplitudes increased with the number of train stimuli for AH, with the strongest facilitation observed at 5Hz. The response amplitude increased 6.1 times on average compared with single-train transcranial electrical stimulation (st-TES). This trend was also observed in the QF. No adverse events (e.g., seizures, cardiac arrhythmias, scalp burns, accidental injury resulting from patient movement) were observed in any patients. Although several facilitative techniques using central or peripheral stimuli, preceding transcranial electrical stimulation, have been recently employed to augment TcMEPs during surgery, responses are still much smaller than CMAPs. Changing from conventional st-TES to mt-TES has potential to greatly enhance TcMEP responses.

RESULTS OF SPINAL DEFORMITY CORRECTION USING TRANSPEDICULAR INSTRUMENTATION IN CHILDREN WITH IDIOPATHIC SCOLIOSIS

Objective. To analyze results of surgical correction of spinal deformity using transpedicular instrumentation in children with idiopathic scoliosis. Material and Methods. A total of 106 patients aged 13 to 18 years with Cobb angle of 40? to 136? were operated on. Out of them 56 (52.8%) patients had Lenke I deformity, 23 (21.7%) – Lenke III, 15 (14.2%) – Lenke V, and 12 (11.3%) – Lenke VI scoliosis. Results. The deformity correction achieved after surgery was 48 % to 100 % in patients with Lenke I, 72 % to 100 % – with Lenke III, 81 % to 100 % – with Lenke V, and 75 % to 100 % – in patients with Lenke VI scoliosis. Derotation of the apical vertebra varied between 0 % and 77 % in Lenke I scoliosis, between 10 % and 79 % in Lenke III, between 9 % and 57 % in Lenke V scoliosis. In patients with Lenke VI idiopathic scoliosis the apical vertebra derotation was 10 % to 58 % in the thoracic spine and 7 % to 50 % in the lumbar spine. Extension of the fixation region ranged from 10 to 14 vertebrae in Lenke I idiopathic scoliosis, from 7 to 12 – in Lenke III, from 5 to 9 – in Lenke V, and from 11 to 14 vertebrae – in Lenke VI idiopathic scoliosis. Conclusion. The total transpedicular fixation along the curvature length allows performing effective correction, true derotation of apical vertebral bodies, and stable preservation of the achieved results postoperatively.

Sexual function in older adults following thoracolumbar to pelvic instrumentation for spinal deformity

Sexual function is an often-overlooked aspect of health-related quality of life among older adults treated for spinal deformity. The authors' objective was to assess sexual function among older adults following thoracolumbar fusion with pelvic fixation for spinal deformity. This was a retrospective review of consecutive older adults (≥50 years) treated with posterior thoracolumbar instrumentation (including pelvic fixation) for spinal deformity and with a minimum 18-month follow-up. Patients completed the Changes in Sexual Function Questionnaire-14 (CSFQ-14), Oswestry Disability Index (ODI), and 12-Item Short-Form Health Survey (SF-12). Sixty-two patients (45 women and 17 men) with a mean age of 70 years (range 50-83 years) met the inclusion criteria. Eight women did not complete all questionnaires and were excluded from the subanalysis. The mean number of instrumented levels was 9.8 (range 6-18), and the mean follow-up was 36 months (range 19-69 months). Based on the CSFQ-14, 13 patients (24%) had normal sexual function, and 8 (15%), 10 (19%), and 23 (42%) had mild, moderate, and severe dysfunction, respectively. Thirty-nine percent of patients reporting severe sexual dysfunction did not have available partners-23% because of a partner's death and 16% because of a partner's illness)-or had significant medical comorbidities of their own (48%). Thirty-nine percent of assessed patients had either no or only mild sexual dysfunction. Patients with minimal or mild disability tended to have no or mild sexual dysfunction. The authors of this study assessed sexual function in older adults following surgical correction of spinal deformity that included posterior instrumented fusion and iliac bolts. Nearly 40% of assessed patients had either no or only mild sexual dysfunction, suggesting that despite an older age and extensive spinopelvic instrumentation, it remains very possible to maintain or achieve satisfactory sexual function.

Development of a Detailed Volumetric Finite Element Model of the Spine to Simulate Surgical Correction of Spinal Deformities

A large spectrum of medical devices exists; it aims to correct deformities associated with spinal disorders. The development of a detailed volumetric finite element model of the osteoligamentous spine would serve as a valuable tool to assess, compare, and optimize spinal devices. Thus the purpose of the study was to develop and initiate validation of a detailed osteoligamentous finite element model of the spine with simulated correction from spinal instrumentation. A finite element of the spine from T1 to L5 was developed using properties and geometry from the published literature and patient data. Spinal instrumentation, consisting of segmental translation of a scoliotic spine, was emulated. Postoperative patient and relevant published data of intervertebral disc stress, screw/vertebra pullout forces, and spinal profiles was used to evaluate the models validity. Intervertebral disc and vertebral reaction stresses respected published in vivo, ex vivo, and in silico values. Screw/vertebra reaction forces agreed with accepted pullout threshold values. Cobb angle measurements of spinal deformity following simulated surgical instrumentation corroborated with patient data. This computational biomechanical analysis validated a detailed volumetric spine model. Future studies seek to exploit the model to explore the performance of corrective spinal devices.

Surgical Correction of Spinal Deformity in Patients With Cerebral Palsy Using Pedicle Screw Instrumentation

Retrospective review of a prospectively collected single surgeon's series. To investigate the efficacy of pedicle screw instrumentation in correcting spinal deformity in patients with quadriplegic cerebral palsy. In addition to assess quality-of-life and functional improvement after deformity correction as perceived by the parents of our patients. All pedicle screw constructs have been commonly used to correct adolescent idiopathic scoliosis. There is limited information on their effectiveness in treating patients with cerebral palsy and neuromuscular scoliosis. We reviewed the medical records and serial radiographs of 45 consecutive patients with quadriplegia who underwent spinal arthrodesis using pedicle screw/rod instrumentation and a standardized surgical technique. All patients were wheelchair bound with collapsing thoracolumbar scoliosis and pelvic obliquity. Twenty-eight patients had associated sagittal deformities. A telephone survey was performed by an independent investigator to assess parents' perception on surgical outcome. Thirty-eight patients underwent posterior-only and 7 staged anteroposterior spinal arthrodesis. Mean age at surgery was 13.4 years (range: 9 to 18.3 y) and mean postoperative follow-up was 3.5 years (range: 2.8 to 5 y). Pedicle screw instrumentation extended from T2/T3 to L5 with bilateral pelvic fixation using iliac bolts. Scoliosis was corrected from mean 82.5 to 21.4 degree (74.1%). Pelvic obliquity was corrected from mean 24 to 4 degree (83.3%). In posterior-only procedures, average blood loss was 0.8 blood volumes, intensive care unit stay 3.5 days, and hospital stay 17.6 days. In anteroposterior procedures, average blood loss was 0.9 blood volumes, intensive care unit stay 8.9 days, and hospital stay 27.4 days. Major complications included 1 deep infection and 1 reoperation to remove prominent implants but no deaths, no neurological deficit, and no detected pseudarthrosis. Parents' survey showed 100% satisfaction rate. Pedicle screw instrumentation can achieve excellent correction of spinal deformity in quadriplegic cerebral palsy with low complication and re-operation rates and high parent satisfaction.

Application of Intraoperative Computed Tomography With or Without Navigation System in Surgical Correction of Spinal Deformity

A retrospective analysis of patients undergoing spinal deformity correction surgery by the assistance of intraoperative computed tomography (iCT) with or without navigation system. To share our preliminary experience and analysis of the iCT navigation system applied to spinal deformity surgery. The iCT navigation system has been shown to improve accuracy and safety in posterior instrumentation. It not only decreased the operation time but also prevented excessive radiation exposure to the medical staff. To date, there are only few reports about the application of the iCT navigation system in spinal deformity surgery. From April 2009 to September 2010, 59 patients who had a diagnosis of scoliosis, kyphosis, or scoliokyphosis and underwent iCT-assisted surgical correction were included. Without randomization, 28 patients were operated with the iCT-navigation system, and the other 31 patients were operated with standard procedure under iCT assistance. The detailed procedures, preoperative and intraoperative images were illustrated. The accuracy of screw placement, time for screw insertion, postoperative correction rate, and iCT scanning data were analyzed. There were significant differences between 2 groups in (1) the preoperative Cobb angle (76.2° and 62.6° in the navigation and non-navigation groups), (2) the accuracy and the revision rate of thoracic pedicle screws and total pedicle screws, and (3) the average screw insertion time. The breach rate and the revision rate of thoracic pedicle screws and total pedicle screws were significantly lower and the average screw insertion time was significantly lesser in the navigation group than in the non-navigation group. There were no statistically significant difference in (1) the breach rate and the revision rate of lumbar pedicle screws, (2) the mean iCT scanning time and time-out, (3) the mean number of fusion segments, (4) the mean number of iCT scans, and (5) the postoperative correction rate. Complications were encountered in 2 patients in the non-navigation group but none in the navigation group. There was no reoperation due to implant malposition in both groups. The iCT navigation system provides desirable accuracy of posterior spinal instrumentation for patients during surgical correction of spinal deformity without radiation exposure to the medical staff, especially in thoracic spine instrumentation. Meanwhile, the iCT in itself is an effective means of assessing complex instrumentation of the spinal deformity.

ADAPTIVE MORPHOGENETIC MECHANISMS IN SCOLIOTIC SPINE STRUCTURES

Objective. Analysis of morphological criteria of formation of secondary growth plate and vertebral body torsion in scoliosis. Material and Methods. Specimens of vertebral body growth plates from convex and concave sides of deformity, intervertebral discs, and bone tissue were obtained during surgical correction of spinal deformity in 60 patients age 6–14 with II–IV grade idiopathic scoliosis. Structural components of the spine of children age 10–14 obtained from the Department of Forensic Medicine were used as controls. Specimens were analyzed using morphological, histochemical, and immunohistochemical methods and ultrastructural analysis. Results. Proliferative activity of chondrocytes in the concave zone of the growth plate and in loose areolar tissue of the disc with isogenous groups and columnar structures, which repeat the stages of growth plate chondroblast differentiation, is specified as a secondary growth plate. Secondary growth zone is a biomechanical adaptive mechanism of congruency formation type. Second process of vertebral body torsion also may be characterized as adaptive mechanism. A change in the structural organization of the growth plate is observed at early stages of scoliotic spinal deformity (Grade II). Formation of columnar structures is disturbed; isogenic groups of cells are at the angle of 45° to the axis of the spine. Conclusion. The formation of bone structures in accordance with the violation of the chondroblast architectonics in the growth plate is a morphological substrate of the torsion, and explains the interdependence or the priority of the torsion in the formation of wedge-shaped vertebrae.

PREVENTION OF NEUROLOGICAL COMPLICATIONS IN CORRECTION SURGERY FOR SEVERE SPINAL DEFORMITIES

Objective. To assess the efficacy of neurological complication prevention by multimodal intraoperative monitoring of spinal cord functioning. Material and Methods. Results of intraoperative spinal cord monitoring in 457 patients during spine correction surgery for grade IV scoliosis with application of the third-generation segmental instrumentation were analyzed. The magnitude of scoliotic curvature exceeded 80 degrees in 353 patients. All patients underwent continuous intraoperative monitoring of lower extremity skin temperature. Out of them, in 45 patients somatosensory evoked potentials were recorded, and in 41 patients intraoperative Stagnara wake-up test was performed. Results. Neurological complications were registered in 4 patients as lower atonic paraplegia which accompanied with rapid rise in lower extremity skin temperature more than by 1 °C during spinal deformity correction. In two of them SSEP recording showed a sharp decrease in the amplitude of potential waves up to their complete disappearance. Skin temperature monitoring of lower extremities did not revealed significant changes in patients without neurological complications. Conclusion. Multimodal intraoperative monitoring of the spinal cord function should be performed in patients with high risk of neurological complications after surgical correction of spinal deformity.

The prevention of neural complications in the surgical treatment of scoliosis: the role of the neurophysiological intraoperative monitoring

Iatrogenic spinal cord injury is the most feared complication of scoliosis surgery. The importance of combined somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) monitoring during spine surgery is well known. The current authors retrospectively evaluated the results of neurophysiological intraoperative monitoring (IOM) in a large population of patients who underwent surgical treatment for spinal deformity. Intraoperative monitoring of SEPs and transcranial electrical stimulation MEPs (TES-MEP) was performed in 172 successive patients who underwent surgical treatment of idiopathic (128 pts), congenital (15 pts) or syndromic (29 pts) scoliosis. The first 106 patients (Group 1) underwent only SEP monitoring, while the other 66 patients (Group 2) underwent combined SEP and TES-MEP monitoring, when the technique was introduced in the current authors' institution. Halogenate anaesthesia (Sevoflurane, MAC 0.6-1.2) was performed in Group 1 cases, total intravenous anaesthesia (Propofol infusion, 6-10 mg/kg/h) in Group 2 patients. A neurophysiological "alert" was defined as a reduction in amplitude (unilateral or bilateral) of at least 50% for SEPs and of 65% for TES-MEPs compared with baseline. In Group 1, two patients (1.9%) developed postoperative neurologic deficits following surgical correction of spinal deformity, consisting of permanent paraparesis in one case and transient paraparesis secondary to spinal cord ischaemia in the other. Twelve patients presented intraoperative significant changes of neurophysiological parameters that improved following corrective actions by surgeons and anaesthesiologists, and did not show any postoperative neurologic deficits. In ten cases the alert was apparently unrelated to surgical manoeuvres or to pharmacological interventions and no postoperative neurologic deficits were noted. Considering the patients of Group 2, two patients (3.0%) presented transient postoperative neurologic deficits preceded by significant intraoperative changes in SEPs and TES-MEPs. In five cases a transient reduction in the amplitudes of SEPs (1 patient) and/or TES-MEPs (5 patients) was recorded intraoperatively with no postoperative neurologic deficits. In conclusion, in the current series of 172 patients the overall prevalence of postoperative neurologic deficit was 2.3% (4 patients). When combined SEP and TES-MEP monitoring was performed, the sensitivity and specificity of IOM for sensory-motor impairment was 100 and 98%, respectively. Combined SEP and TES-MEP monitoring must be regarded as the neurophysiological standard for intraoperative detection of emerging spinal cord injury during corrective spinal deformity surgery. Early detection affords the surgical team an opportunity to perform rapid intervention to prevent injury progression or possibly to reverse impending neurologic sequelae.

Structural and functional peculiarities of spine deformity development in neurofibromatosis NF-1

To study pathogenetic mechanisms of the development of spinal deformity in neurofibromatosis.Structural components of the spine were presented as specimens obtained after surgical correction of spinal deformity performed in 10 children with III—IV grade scoliosis associated with neurofibromatosis.Etiologic factor of the development of spinal deformity in neurofibromatosis is a mutation of the NF-1 gene in cells of ganglious lamella. Migration of cells carrying mutant gene into one of the sclerotome zones results in oncogene activation and intensive proliferation of chondro-, osteo-, and fibroblasts in the growth plate, intervertebral disc, and vertebral body.Progressive development of the spinal deformity after surgical intervention is accounted both for proliferation of chondro- and fibroblasts in the vertebral body and intervertebral disc and for disturbance of the NF-1 and lumican genes expression.

Autologous Blood Donation Programs in Surgical Correctionof Spinal Scoliotic Deformity

Objective. To develop the programs of autologous blood deposition to compensate blood loss in surgical correction of spinal deformity. Material and Methods. The study included 145 patients with spinal deformities who underwent one- and two-stage selective surgical interventions. In the study group (n = 100) autologous blood components were preoperatively deposited for intra- and postoperative blood loss compensation; in the control group (n = 45) prior deposition was not performed. Results. It was found that, taking into account the terms of autologous blood shelf life and efficacy, a prior deposition of 20 % of total blood volume (TBV) providing compensation of blood loss up to 40–45 % of TBV is optimal for one-stage surgical intervention, and deposition of 30 % of TBV allowing loss compensation of 50–55 % of TBV is enough for twostage surgery. Conclusion. Autologous blood deposition is an effective method for blood loss compensation. Blood deposition volume and techniques are determined by an expected blood loss associated with specific surgical intervention.

Surgical correction of spinal deformity in patients with congenital muscular dystrophy

BackgroundCongenital muscular dystrophy (CMD), among the myopathic disorders is one form of flaccid neuromuscular disorder (NMD). Patients with NMD frequently develop progressive spinal deformity. For NMD patients who have a severe spinal deformity, sitting is often difficult and is accompanied by pain and breakdown of the skin. Spinal deformity surgery in these patients has been highly effective in stabilizing the spine, maintaining upright, comfortable sitting balance, and improving patients’ quality of life. However, many studies have reported significant rates of peri/postoperative complications in these patients. To our knowledge, there has been no study on the results of spinal deformity surgery in patients with CMD. The purpose of this study was to review the clinical and radiological results of spinal deformity surgery in this group of patients with CMD. MethodsBetween 2004 and 2007, a total of 10 CMD patients underwent scoliosis surgery. There were three patients with Fukuyama CMD, three with Ullrich CMD, and 4 with nonsyndromic CMD (merosin-negative). They were nonambulatory. All the patients had standard posterior spinal fusion and pedicle-screw-alone fixation from T3 or T4 to L5 for spinal deformity. Our inclusion criteria required that each patient (1) had considerable difficulty with sitting balance and pain or breakdown of the skin due to scoliosis; (2) was able to ventilate his or her lung autonomously; (3) was not ventilator-dependent; and (4) did not have cardiac failure. Sufficient informed consent was important, and the decision to perform surgery was made by the patient/family with sufficient preoperative informed consent. Patients were trained with inspiratory muscle training (IMT) using an inspiratory muscle trainer (Threshold IMT) for 6 weeks prior to surgery Cardiac function was assessed preoperatively. Pulmonary function tests were performed preoperatively and postoperatively. Radiographic assessments were performed on sitting anteroposterior (AP) and lateral radiographs. These assessments were made periodically. The Cobb angles of the curves and spinal pelvic obliquity (SPO) on the coronal plane, thoracic kyphosis, and lumbar lordosis were measured. The preoperative AP radiograph and side-bending films were examined to determine flexibility. Patients’ and parents’ satisfaction were surveyed by a self-completed questionnaire at the last follow-up. ResultsPercent forced vital capacity (%FVC) increased from a mean of 30% before IMT to a mean of 34% the day before surgery. The preoperative scoliosis was 75° (range 61°–95°). The scoliotic curvature on preoperative side-bending films was 19° (range 11°–28°). All patients were extubated on the day of surgery. No patients developed cardiac or respiratory complications. The scoliotic curvature was 18° (range 10°–25°) immediately after surgery, and 19° (range 12°–27°) at the last follow-up. The pelvic obliquity improved from a mean of 17° (range 14°–20°) preoperatively to a mean of 6° (range 4°–9°) postoperatively and to 7° (range 4°–10°) at the last follow-up. Balanced sitting posture was achieved and maintained. On the sagittal plane, good reconstruction of sagittal plane alignment was recreated and maintained. There were no major complications or deaths. All patients/parents completed the outcome satisfaction questionnaire. Eight patients/parents were very satisfied and two were satisfied. ConclusionsPedicle-screw-alone fixation and fusion to L5 was safe and effective in CMD patients with scoliosis of <95° and pelvic obliquity of <20°. Scoliosis curves were flexible (75% correction) on side-bending films preoperatively. Curve correction and maintenance of correction in the coronal and sagittal plane was excellent. The pelvic obliquity significantly improved. Balanced sitting posture was achieved and maintained in all patients. Our patients with CMD spinal deformity and a moderately and severely decreased FVC could be operated on safely and successfully with general anesthesia. All patients were extubated in the operating room. There were no major complications or deaths. We believe a FVC of <30% alone is not a predisposition to pulmonary complications. However, cardiomyopathy might be a determining risk of mortality, and we believe surgery for these patients should be avoided. Patients’ and parents’ satisfaction was high.