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PubMed1993

Scoliosis associated with syringomyelia.

From January 1986 to December 1991, 1,059 patients with scoliosis of 20 degrees or more were reviewed. By magnetic resonance imaging, 43 patients were found to have syringomyelia. Thirty-eight patients had Chiari type 1 malformation. Twenty-two of the patients were younger than 10 years. Scoliosis was the only presenting symptom in 32 patients. All patients had some neurologic abnormalities. Fifteen patients had left thoracic curves. The incidence of scoliosis with syringomyelia in our outpatient clinic was 4.0%; 18.4% in boys, and 2.6% in girls. Magnetic resonance imaging should be performed in patients who have abnormal neurologic findings.

Adolescent↗
PubMed1993

A preliminary investigation of shape memory alloys in the surgical correction of scoliosis.

Nitinol, a shape memory alloy, is flexible at low temperatures but retains its original shape when heated. This offers interesting possibilities for scoliosis correction. Of the shape memory alloys, nitinol is the most promising medically because of biocompatibility and the ability to control transition temperature. In vivo: Six goats with experimental scoliosis were instrumented with 6-mm nitinol rods. The rods were transformed, and the scoliosis corrected, in the awakened goats by 450-kHz radio frequency induction heating. The curves averaged 41 degrees before instrumentation, 33 degrees after instrumentation, and 11 degrees after rod transformation. The animals tolerated the heating without discomfort, neurologic injury, or evidence of thermal injury to the tissues or the spinal cord. In vitro: Nitinol rods were tested under both constant deflection and constant loading conditions and plotted temperature versus either force or displacement. The 6-mm rod generated forces of 200 N. The 9-mm rod generated up to 500 N. We safely coupled shape memory alloy transformation to the spine and corrected an experimental spinal deformity in awake animals. The forces generated can be estimated by the rod's curvature and temperature. The use of shape memory alloys allows continuous neurologic monitoring during awake correction, true rotational correction by rod torsion, and the potential option of periodic correction to take advantage of spinal viscoelasticity and the potential of true rotational correction by rod torsion.

Alloys↗
PubMed1994

Adult lumbar scoliosis. Epidemiologic aspects in a low-back pain population.

The frequency and characteristics of definite lumbar scoliosis in an adult common low-back pain population (n = 671) were assessed by a clinical and radiologic prospective study. The prevalence was 7.5% (N = 50), increasing with age: 2% before 45 years; 15% after 60 years. Scoliosis was revealed by low-back pain in adulthood in 86% of the cases. The mean Cobb angle was 21 +/- 11.4 degrees. A Cobb angle of more than 30 degrees was noted in 16% of the scoliotics, thus 1% of the entire population. The proportion of women increased with the severity of the scoliosis. Right and left side scolioses were equally noted. A correlation between the Cobb angle and age was found (0.3 degrees/yr; P < 0.05). Rotatory olisthesis was noted in 34% of the cases, more often in right side curves (P < 0.01). The lumbar scoliotic patients were distinguished by a more advanced age (62 +/- 12.4 yr vs. 49.6 +/- 15.5 yr; P < 0.001), a greater proportion of women (72% vs. 48%; P < 0.01), and a more likely involvement of L3 and L4 radicular pain (P < 0.05). Radicular thigh pain was related to unstable curves (P < 0.01). The lumbar scoliotic patients thus constitute a subgroup within the low-back pain population.

Adult↗
PubMed1994

Pulmonary functions in congenital scoliosis.

STUDY DESIGN: Thirty-six patients with congenital scoliosis underwent full clinical and radiologic evaluation of their deformity and their full pulmonary functions. OBJECTIVES: This study observed pulmonary functions in congenital scoliosis in detail, evaluated pulmonary functions in nonsurgically treated patients, and established whether, in surgically treated patients, there are any differences between those with multiple thoracic anomalies and those with lumbar or one of two thoracic anomalies. SUMMARY OF BACKGROUND DATA: Eighty-six of our patients in both groups (surgically and nonsurgically treated) showed abnormal increases in residual volumes, indicating a restrictive pattern of lung function. The results of their pulmonary functions were analyzed using predicted values to eliminate age affect. METHODS: Pulmonary functions were assessed using the Gould 5000IV Computerized Pulmonary Function System. RESULTS: Overall, mean total lung capacity was 89% of predicted value, and mean vital capacity and forced vital capacity were 74% of predicted value. The mean residual volume was significantly increased, being 154% of predicted value. Nonsurgically treated patients showed normal total lung capacity (mean 99.8% of predicted value); this mean value was 82% of predicted value in surgically treated patients. CONCLUSION: Vital capacity was found to be significantly reduced in surgically treated patients (68% of predicted value), especially in those patients who had multiple thoracic anomalies. We believe that children with congenital scoliosis due to multiple anomalies should be operated on at an early age before deformity is too severe.

Adolescent↗
PubMed1994

Changes in shape of the adolescent idiopathic scoliosis curve after surgical correction.

STUDY DESIGN: The effect of spinal instrumentation in idiopathic scoliosis was studied in 21 patients who had Harrington instrumentation and 15 who had Wisconsin-Drummond instrumentation. OBJECTIVE: Radiographs were analyzed to determine if the frontal and transverse plane shape of the scoliosis curve was changed by surgery, with and without segmental fixation. SUMMARY OF BACKGROUND DATA: Previous reports were based on frontal plane measurements of the curve (Cobb angle). The study reports correction in the frontal plane (Cobb angle) and transverse plane (apical vertebral rotation), as well as the regional distribution of the correction. METHODS: Radiographs before surgery, soon after, and between 5 and 48 months after surgery were marked and digitized to measure the regional distribution of the frontal plane shape and transverse plane vertebral rotation. RESULTS: Despite improvement in the magnitude of the deformity, the scoliosis curve shape remained almost constant postoperatively. There was minimal correction of the apical vertebra axial rotation in either group. CONCLUSION: This study documents that although the Harrington and Wisconsin-Drummond instrumentation systems decrease the Cobb angle, they do not change the shape of the curve or correct apical vertebra axial rotation. Newer instrumentation designs need to look beyond the Cobb angle as the only measure of outcome.

Adolescent↗
PubMed1994

Posterior spinal fusion in neuromuscular scoliosis using a tibial strut graft. Results of a long-term follow-up.

STUDY DESIGN: Risks and benefits of using a tibial graft for posterior spinal fusion in neuromuscular scoliosis were evaluated in a long-term follow-up study. A consecutive series of 72 patients underwent posterior spinal fusion for neuromuscular scoliosis. OBJECTIVES: Radiologic outcome was assessed to evaluate the quality of the spinal fusion. Patients were followed serially to detect donor site complications. Mean follow-up was 17 years and 8 months (minimum: 6 years, 6 months). SUMMARY OF BACKGROUND DATA: Mean age of the patients at the time of surgery was 15 years. Progression of the curvature was minimal at last follow-up (mean progression at last follow-up: lumbar curve, 4.5 degrees; thoracic curve, 5.3 degrees). Concerning donor site complications, four patients had a leg length discrepancy of less than 2 cm at last follow-up. This complication was related to tibial overgrowth at the donor site. METHODS: Solid fusion was defined in this long-term study as the absence of modification of the radiologic aspect at last follow-up in addition to the presence of a massive contagious trabecular fusion mass. RESULTS: The fusion appeared to be solid in all patients. No obvious pseudarthrosis could be documented. The constant successful outcome differs significantly from spinal fusion that uses bank bone. The absence of stress fracture was correlated to the low level of constraint in this essentially nonambulatory population. CONCLUSION: This experience indicates that the tibial graft deserves consideration in posterior spinal fusion for neuromuscular scoliosis.

Adolescent↗
PubMed1994

Progressive congenital scoliosis treatment using a transpedicular anterior and posterior convex hemiepiphysiodesis and hemiarthrodesis. A preliminary report.

STUDY DESIGN: Patients treated with a transpedicular anterior and posterior convex hemiepiphysiodesis and hemiarthrodesis for progressive congenital scoliosis were followed to evaluate this treatment. OBJECTIVE: To evaluate an alternative to a separate anterior approach for performing an anterior hemiepiphysiodesis for progressive congenital scoliosis. SUMMARY OF BACKGROUND DATA: Previous investigators have reported a transpedicular anterior fusion combined with a bilateral posterior fusion. The authors are unaware of a previous report on a transpedicular anterior convex hemiepiphysiodesis and fusion combined with a unilateral convex posterior spinal fusion to treat progressive congenital scoliosis. METHODS: Nineteen curves were fused in 16 patients who had a variety of congenital anomalies. The average age at surgery was 4.8 years (range, 11 months to 13 years) The average follow-up period was 4.8 years (range, 2 to 9.6 years). RESULTS: The average preoperative and postoperative fused curves measured 36 degrees and 38 degrees, respectively. Of the 19 fused curves, seven curves (37%) improved, eight curves (42%) were unchanged or progressed less than 7 degrees, three curves (16%) progressed 10 degrees to 15 degrees, and one curve (5%) progressed more than 15 degrees. CONCLUSIONS: This procedure appears to be most effective in arresting growth in the young patient who has an isolated hemivertebrae and no excessive kyphosis. The epiphysiodesis effect is less predictable.

Bone Transplantation↗
PubMed1995

Meta-analysis of surgical outcome in adolescent idiopathic scoliosis. A 35-year English literature review of 11,000 patients.

STUDY DESIGN: Meta-analysis of the English literature on the surgical treatment of adolescent idiopathic scoliosis. OBJECTIVE: To gather comparable data from a number of different sources and combine the data to create a larger, more statistically significant pool of information for the analysis of surgical outcome. SUMMARY OF BACKGROUND DATA: Meta-analysis is a technique of scientific literature review used in outcome evaluation of medical treatment. This technique has been applied to the surgical outcome of adolescent idiopathic scoliosis. METHODS: A structured literature review was performed that cross-referenced English literature articles pertaining to the surgical treatment of adolescent idiopathic scoliosis with a focus on patient-based outcomes. Measures of patient satisfaction were compared with process measures of care. RESULTS: A number of patients (10,989) were reviewed in 139 patient populations. Unspecified curve types (9424) and King curve types (1565) were reviewed over a 35-year period from 1958 to 1993. Of the patients, 87.32% were studied retrospectively and 12.70% prospectively. Effect-weighted follow-up was 6.8 years. Only studies with complete process and patient data for unspecified or King curve types were included for satisfaction correlation calculations. Pearson product moment correlation for n = 33 studies, n' = 2926 patients revealed a positive r' = 0.628 correlation between degree of curve correction and percent satisfaction per study. To determine the degree of curvature correction resulting in patient satisfaction, a stepwise multiple linear regression analysis was performed with level of confidence (P < or = 0.05). Of significance was that the degree of curvature corrected accounted for all the satisfaction variance predicted. A significant correction exists between degree of curve correction and percent of patients satisfied. The percent of correction and the Group type (either unspecified or King classified), did not significantly alter this prediction. The best predictor of satisfaction appears to be degree of curve correction according to these data. CONCLUSION: Patients appear to be more satisfied by the magnitude of curve correction rather than the percent of curve correction. The degree of curvature before surgery did not predict patient satisfaction. Pearsons r' = 0.045. Satisfaction appears to be best predicted by the degree of correction only and not by the percent curve correction, the curve magnitude before surgery, nor the Group type (King, unspecified). Patient satisfaction is subjective. It does not reflect the benefits of surgery with respect to the future preservation of pulmonary function in thoracic curves nor the prevention of osteoarthritis in lumbar curves.

Adolescent↗
PubMed1995

An evaluation of motor-evoked potentials for detection of neurologic injury with correction of an experimental scoliosis.

STUDY DESIGN: Controlled correction of scoliosis in a rat model was used to assess the accuracy of intraoperative motor-evoked potential monitoring. OBJECTIVES: The purpose of this study was to develop a model in which motor-evoked potential changes could be compared with neurologic function after surgery, such that a threshold for responding to motor-evoked potential changes may be established. SUMMARY OF BACKGROUND DATA: Intraoperative motor-evoked potential monitoring has become technically feasible. Clinical application now depends on the development of useful interpretation parameters and correlation with neurologic sequelae. METHODS: Experimental scoliosis was produced in 30 rat pups. After growth, the rats underwent correction of their scoliosis by distraction. Changes in tcMMEP onset latency and amplitude were measured. Distraction was applied either until a 10% delay in tcMMEP onset latency (Group 1), until tcMMEP responses were ablated (Group 2), or for 10 minutes after the loss of transcranial magnetic stimulation response (Group 3). RESULTS: In Group 1 (n = 10), all animals had tcMMEP with normal onset latency and normal neurologic examinations 24 hours after surgery. In Group 2 (n = 10), tcMMEP were normal in four rats, markedly delayed in three rats, and absent in three rats 24 hours after surgery. neurologic examination was normal in the four rats with normal tcMMEP. Moderate deficit was noted in two of the three rats with prolonged onset latency 24 hours after surgery; the third was intact. Moderate neurologic injury was noted in two of three rats with absent tcMMEP 24 hours after surgery; the third rat was paralyzed. In Group 3 (n = 10), vertebral dislocation was noted on lateral radiographs in eight of 10 animals. Twenty-four hours after surgery, tcMMEP remained absent, and paralysis was noted in the eight rats with dislocation. The two rats without dislocation had delayed tcMMEP but some return of neurologic function. CONCLUSIONS: Comparison of the three groups shows a significant correlation between tcMMEP and endpoint neurologic outcome. None of the rats in Group 1 had a neurologic deficit after surgery as opposed to five of 10 rats in Group 2 and 10 of 10 rats in Group 3 with significant neurologic injury. These findings suggest that a 10% delay in onset latency would be an appropriate threshold for responsing to changes in tcMMEP.

Analysis of Variance↗
PubMed1995

A simple method for improving vertebral visualization on a scoliosis series lateral radiograph.

STUDY DESIGN: This technical note describe a method for improving vertebral body visualization on lateral scoliosis radiographs. OBJECTIVE: To improve vertebral column visualization on lateral radiographs. SUMMARY OF BACKGROUND DATA: The different density of the thoracic and abdominal cavities makes complete visualization of the vertebral column difficult on lateral radiographs. METHODS: An inexpensive, simple filter paper method was used to normalize the densities between adjacent body cavity and improve visualization of the vertebral column on a lateral scoliosis series radiograph. RESULTS: Use of a single-exposure, filter paper technique improved simultaneous visualization of the thoracic and lumbar vertebrae, compared with the standard single-exposure unfiltered technique. CONCLUSION: Accurate lateral vertebral visualization allows effective three-dimensional correlation of the sagittal plane deformity concurrent with the coronal plane deformity of scoliosis. Using a single-exposure, filter paper technique improves sagittal plane spinal visualization. Repeat radiographs and patients exposure are reduced by this technique.

Humans↗
PubMed1996

Thoracic volume changes in scoliosis surgery.

STUDY DESIGN: Eighteen patients with adolescent idiopathic scoliosis treated with ISOLA instrumentation and 13 treated with Cotrel-Dubousset instrumentation were studied before and after surgery with computed tomography scans. OBJECTIVES: To analyze and compare the immediate change in chest volume of patients treated with the derotation method of Cotrel-Dubousset versus the sublaminar wire translational technique of ISOLA. SUMMARY OF BACKGROUND DATA: Previous literature suggests a small but variable improvement in pulmonary function with the use of Harrington instrumentation when treating adolescent idiopathic scoliosis. The effect of modern instrumentation techniques on chest volume and ultimately pulmonary function has not been determined. METHODS: An axial computed tomography slice was made through each vertebral body from T3 to T10. Using a technique of spine curve measurements, the cross-sectional area at each level was computed, and from the height measured, the volume of the thoracic cage was computed. RESULTS: Single thoracic curves (King-Moe Type III) managed with ISOLA sublaminar instrumentation showed a statistically significant increase in chest volume when compared with other curve types and when compared with all curves managed with Cotrel-Dubousset. Seventeen of 18 patients treated with ISOLA instrumentation gained chest volume, whereas half of those treated with Cotrel-Dubousset actually lost volume. CONCLUSIONS: ISOLA instrumentation and sublaminar wiring appears to increase the chest volume in patients with adolescent idiopathic scoliosis. Its clinical significance remains to be determined.

Adolescent↗
PubMed1996

Efficacy and cost considerations of intraoperative autologous transfusion in spinal fusion for idiopathic scoliosis with predeposited blood.

STUDY DESIGN: One hundred five patients with adolescent idiopathic scoliosis who underwent posterior spinal instrumentation and fusion with predeposited autologous blood, with or without intraoperative autologous transfusion, were reviewed. OBJECTIVE: To determine the benefit/nonbenefit of intraoperative autologous transfusion in diminishing the need for homologous blood and influencing post-operative hematocrit values in healthy adolescents undergoing spinal fusion for scoliosis. SUMMARY OF BACKGROUND DATA: A steady increase in the use of intraoperative autologous transfusion in recent years has occurred without guidelines regarding which procedures and patient populations would be best served. Previous studies have failed to determine the cost effectiveness and actual reduction in homologous blood exposure attributable to intraoperative autologous transfusion in adolescents who have undergone preoperative phlebotomy. METHODS: Fifty-five adolescents (intraoperative autologous transfusion group) who underwent posterior instrumentation and fusion for idiopathic scoliosis with the use of an intraoperative autologous transfusion device were compared to 50 patients (control group) who underwent the same procedure without the intraoperative autologous transfusion device. RESULTS: The average percent salvage of red blood cells by the intraoperative autologous transfusion device was 35%. The control group utilized significantly more of the predonated autologous blood than the intraoperative autologous transfusion group (1.34 units/case vs. 1.78 units/case, P < 0.05). Homologous blood usage was the same in both groups. Two patients in the intraoperative autologous transfusion group required nondirected homologous blood (total of four units), compared to three patients in the control group (total of four units) (P = 0.048). Using multiple regression analysis, the total number of transfusions was significantly correlated with the estimated blood loss and the duration of surgery in both groups. Postoperative hematocrit levels were slightly higher in the control group, but there was not a significant difference. CONCLUSIONS: The addition of intraoperative autologous transfusion to a preoperative phlebotomy program had no benefit on homologous blood exposure or post-operative hematocrit changes in this population. Blood requirements for this procedure can be met less expensively and more reliably by merely donating one's own blood.

Adolescent↗
PubMed1996

Melatonin. A possible role in pathogenesis of adolescent idiopathic scoliosis.

STUDY DESIGN: The serum melatonin levels during 24-hour periods were compared between patients with idiopathic and age-matched normal control subjects. OBJECTIVE: To find if the melatonin deficiency may have some role for progression or etiology of idiopathic scoliosis in humans. SUMMARY OF BACKGROUND DATA: Experimentally induced scoliosis in chicken by pinealectomy can be attributed to the defect in melatonin metabolism. METHOD: Blood samples were correlated every 3 hours during 24-hour periods, and serum melatonin levels were measured and statistically analyzed. RESULTS: The level of melatonin, integrated concentration through 24 hours and night time (0:00 am-6:00 am), in the patients who had progressive curve (more than 10 degrees of progression in the previous 12 months) was significantly lower than the level in the patients who had a stable curve (less than 10 degrees of progression in the previous 12 months) or in the control subjects (P < 0.05). CONCLUSION: The study suggests that normal melatonin synthesis or metabolism may have crucial role in regulating normal spine growth. The level of melatonin appears to be a useful predictor for progression of spine curvature in idiopathic scoliosis.

Adolescent↗
PubMed1996

The use of pedicle screw fixation to improve correction in the lumbar spine of patients with idiopathic scoliosis. Is it warranted?

STUDY DESIGN: A retrospective assessment of coronal, sagittal, and axial correction using convex lumbar pedicle screw constructs compared with hook constructs in patients with idiopathic scoliosis. OBJECTIVE: To determine if pedicle screw constructs can improve coronal, sagittal, and axial correction without increased complications and therefore warrant their use in the lumbar spine. SUMMARY OF BACKGROUND DATA: Although hooks have been the traditional fixation choice for posterior scoliosis correction of the lumbar spine, pedicle screws may offer advantages for improved correction of lumbar spinal deformity. METHODS: Twenty-two patients constituted Group A (hooks), in which 17 were double major and five were King Type IV curves. These patients had a minimum follow-up period of 2 years and an average of one hook per lumbar fusion segment. Twenty-two patients constituted Group B (screws), in which 20 were double major and two were King Type IV curves. These patients had a minimum follow-up period of 2 years, and screw configuration consisted of pedicle fixation on the convex side for correction and at times on the concave side for fixation. RESULTS: Pedicle screw fixation constructs had improved lumbar Cobb correction (P < 0.05), lowest instrumented vertebra tilt (P < 0.05), lowest instrumented vertebra translation (P < 0.01), and segmental sagittal alignment from T12 to lowest instrumented vertebra (P < 0.01). There was no significant change in axial rotation using either surgical method. CONCLUSIONS: The use of pedicle screw fixation on the convex portion of the lumbar spine in patients with double major idiopathic scoliosis allows for improved correction of the lumbar Cobb measurement, horizontalization and translation of the lowest instrumented vertebra, and improved segmental lordization over the instrumented levels without increased complications.

Adolescent↗
PubMed1996

The possibility of creating lordosis and correcting scoliosis simultaneously after partial disc removal. Balance lines of lumbar motion segments.

STUDY DESIGN: The feasibility of correcting scoliosis and creating lordosis simultaneously in the thoracolumbar and lumbar spine by anterior instrumentation was investigated by in vitro testing. OBJECTIVES: To evaluate the vertebral zones in which a compressive load applied in a motion segment creates side bending and lordosis in intact motion segments and after partial disc removal. SUMMARY OF BACKGROUND DATA: Most investigators have observed a kyphogenic effect of anterior scoliosis instrumentation and recommended dorsal placement of screws and the use of wedge grafts, although wedge grafts were not used routinely by all surgeons. METHODS: Zones of lordosization and side bending were determined by evaluation of balance lines between extension-flexion and side bending, respectively, by axial loading on ligamentous human motion segments with intact discs and after partial disc removal. RESULTS: In lumbar motion segments with intact discs, it is possible to achieve ipsilateral side bending and lordosization by anterior instrumentation. After partial disc removal, the balance line between extension and flexion runs through the ipsilateral pedicle, and, therefore, a compressive load between the vertebral bodies always creates kyphosis. CONCLUSIONS: After partial disc removal, it is not possible to create lordosis and correction of scoliosis simultaneously by ipsilateral anterior instrumentation without the use of intervertebral wedge grafts.

Adult↗
PubMed1997

Rib cage-spine coupling patterns involved in brace treatment of adolescent idiopathic scoliosis.

STUDY DESIGN: The three-dimensional (3-D) interrelations in the correction of the spine and rib cage produced by the Boston brace were analyzed in a group of adolescents with idiopathic scoliosis. OBJECTIVES: To investigate the coupling movements between the spine and rib cage initiated by brace wear (i.e., the displacements of the spine that take place in other directions than the ones generated by brace pressures on the thorax). SUMMARY OF BACKGROUND DATA: The effects of thoraco-lumbo-sacral orthosis in the frontal plane have been well documented, but they have never been studied in terms of 3-D coupled movements between the spine and rib cage. METHODS: The spine and rib cage of 36 adolescents with idiopathic scoliosis with and without their Boston brace were reconstructed in 3-D using a stereo-radiographic technique. Several geometric indices were evaluated on the trunk, and the relative motions of the spine and rib cage resulting from brace wearing were compared by means of Student t tests, Pearson correlation matrices, and linear regressions. RESULTS: Rib cage transverse plane translations resulting from brace pressures are related to those of the spine. Coupled movements between the spine and rib cage were found to alter substantially the expected 3-D correction of the trunk. Significant anterior displacements of the thorax were observed and were statistically associated with lateral displacements of the spine and with an increase of spinal thoracic curvatures in the frontal and sagittal planes. CONCLUSION: Brace loads are not applied in an optimal way to correct the 3-D deformities associated with thoracic idiopathic scoliosis. Loads applied on the posterior rib hump should be reequilibrated to reduce anterior displacement of the trunk.

Biomechanical Phenomena↗
PubMed1997

Measurement of vertebral rotation in adolescent idiopathic scoliosis using three-dimensional magnetic resonance imaging.

STUDY DESIGN: This report examines a technique for measurement of axial vertebral rotation using magnetic resonance imaging. OBJECTIVES: To assess the reproducibility of three-dimensional magnetic resonance imaging in the measurement of vertebral rotation at individual endplates in patients with adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Deformity in the sagittal and coronal planes in patients with adolescent idiopathic scoliosis can be readily assessed from plain radiographs, but the degree of deformity in the axial plane is more difficult to determine. Plain film techniques have inherent inaccuracies because of loss of definition of anatomic landmarks, and the use of computed tomography is limited by the high radiation dose associated. Magnetic resonance imaging provides a means of imaging scoliotic deformity that allows multiplanar reconstruction and that involves no use of ionizing radiation. METHODS: Ten patients with adolescent idiopathic scoliosis were imaged in a Siemens 1-Tesla impact scanner. Three-dimensional volume images of the apical five vertebrae were obtained in the axial plane and were postprocessed through multiplanar reconstruction. Sections through the superior and inferior endplates of each vertebra were selected in the sagittal and coronal planes, allowing axial reconstructions to be obtained in the plane of each endplate. Vertebral rotation was measured by identifying datum points on the inner surfaces and at the junction of the laminas and comparing the angle subtended by these points with a vertical drawn by the computer. Measurements were obtained from the single scanning sequence on two occasions by one observer and on one occasion by a second observer. Interobserver and intraobserver error was evaluated and correlation with readings obtained from plain films using Perdriolle's torsiometer method assessed. RESULTS: The interobserver variation had a mean of 3.02 degrees (range, 0-10 degrees) and a 95% confidence interval of [2.51 degrees, 3.53 degrees]. The intraobserver variation had a mean of 2.56 degrees (range, 0-7 degrees) and a 95% confidence interval of [1.83 degrees, 3.29 degrees]. The mean difference between measurements obtained from magnetic resonance imaging and plain film was 3.29 degrees (range, 0-12 degrees) with a 95% confidence interval of [1.43 degrees, 5.15 degrees]. CONCLUSIONS: The degree of vertebral rotation can be accurately and reproducibly assessed by three-dimensional magnetic resonance imaging. Measurements can be made through individual endplates that allow assessment of the relative amount of intervertebral and intravertebral deformity.

Adolescent↗
PubMed1997

Continuous electromyographic monitoring to detect nerve root injury during thoracolumbar scoliosis surgery.

STUDY DESIGN: The results of intraoperative monitoring during a case of nerve root injury sustained from scoliosis surgery to the thoracolumbar spine are described. OBJECTIVES: To improve the efficacy of intraoperative monitoring in preventing nerve root injury during scoliosis surgery. SUMMARY OF BACKGROUND DATA: Posterior tibial nerve somatosensory-evoked potentials are the electrophysiologic modality most commonly used for spinal cord monitoring during thoracolumbar spine surgery. Although radiculopathy is a more frequent postoperative complication than myelopathy, monitoring of mixed-nerve, somatosensory-evoked potentials may not detect injuries to individual nerve roots. METHODS: The patient described in this report developed left L5 radiculopathy after scoliosis surgery to the thoracolumbar spine. During surgery, intraoperative electromyographic monitoring identified frequent trains of neurotonic discharges in the left anterior tibial muscle. Bilateral, posterior, tibial nerve, somatosensory-evoked potentials remained normal. The left L5 nerve root was explored 9 days after the original surgery and was found to be compressed by bony structures. Electrophysiologic testing showed that the nerve root had undergone significant Wallerian degeneration, but remained in partial continuity. RESULTS: Nerve root injury was detected by neurotonic discharges identified during intraoperative electromyographic monitoring, but not by somatosensory-evoked potentials, which remained normal. When the injured nerve root was explored, a simple electromyographic technique was used to characterize the extent and type of injury. CONCLUSIONS: The authors of this study recommend electromyographic monitoring of appropriate lumbosacral myotomes in addition to somatosensory-evoked potentials during this type of procedure.

Adult↗