Factors influencing spinal curvature measurements on ultrasound images for children with adolescent idiopathic scoliosis (AIS).

The measurements of spinal curvatures using the ultrasound (US) imaging method on children with scoliosis have been comparable with radiography. However, factors influencing the reliability and accuracy of US measurement have not been studied. The purpose of this study is to investigate the effects of curve features and patients' demographics on US measurements and to determine which factors influence the reliability and accuracy. Two hundred children with scoliosis were recruited and scanned with US by one experienced operator and three trainees. One experienced rater measured the proxy Cobb angles from US images twice one week apart and compared the results with clinical radiographic records. The correlation and accuracy between the US and radiographic measurements were subdivided by different curve severities, curve types, subjects' weight status and US acquisition experiences. A total of 326 and 313 curves were recognized from radiographs and US images, respectively. The mean Cobb angles of the 13 missing curves were 17.4±7.4° and 11 at the thoracic region. Among the 16 curves showing large discrepancy (≥6°) between US and radiographic measurements, 7 were main thoracic and 6 were lumbar curves. Twelve had axial vertebral rotation (AVR) greater than 8°. The US scans performed by the experienced operator showed fewer large discrepancy curves, smaller difference and higher correlation than the scans from the trainees (3%, 1.7±1.5°, 0.95 vs 6%, 2.4±1.8°, 0.90). Only 4% missing and 5% large discrepancy curves were demonstrated for US measurements in comparison to radiography. The missing curves were mainly caused by small severity and in the upper spinal region. There was a higher chance of the large discrepancy curves in the main thoracic and lumbar regions with AVR>8°. A skilled operator acquired better US images and led to more accurate measurements especially for those subjects with larger curvatures, AVR and body mass index (BMI).

Intraoperative spinal cord monitoring using low intensity transcranial stimulation to remove post-activation depression of the H-reflex.

OBJECTIVE: To investigate whether low intensity transcranial electrical stimulation (TES) can be used to condition post-activation depression of the H-reflex and simultaneously monitor the integrity of spinal motor pathways during spinal deformity correction surgery. METHODS: In 20 pediatric patients undergoing corrective surgery for spinal deformity, post-activation depression of the medial gastrocnemius H-reflex was initiated by delivering two pulses 50-125ms apart, and the second H-reflex was conditioned by TES. RESULTS: Low intensity TES caused no visible shoulder or trunk movements during 19/20 procedures and the stimulation reduced post-activation depression of the H-reflex. The interaction was present in 20/20 patients and did not diminish throughout the surgical period. In one case, the conditioning effect was lost within minutes of the disappearance of the lower extremity motor evoked potentials. CONCLUSION: Post-activation depression was used to detect the arrival of a subthreshold motor evoked potential at the lower motor neuron. The interaction produced minimal movement within the surgical field and remained stable throughout the surgical period. SIGNIFICANCE: This is the first use of post-activation depression during intraoperative neurophysiological monitoring to directly assess the integrity of descending spinal motor pathways.

Improvement on the Accuracy and Reliability of Ultrasound Coronal Curvature Measurement on Adolescent Idiopathic Scoliosis With the Aid of Previous Radiographs.

STUDY DESIGN: Retrospective study of the coronal curvature measurement on ultrasound (US) images with the aid of previous radiographs. OBJECTIVE: To compare the reliability and accuracy of the coronal curvature measurements from US images on children who have adolescent idiopathic scoliosis (AIS) with and without the knowledge of previous radiographs. SUMMARY OF BACKGROUND DATA: Using US imaging technique to measure coronal curvature on children with AIS has demonstrated high intra- and interrater reliabilities. However, the selection of end-vertebrae and the measurement difference between radiography and the US method were only moderately reliable. METHODS: Two raters measured the coronal curvatures from 65 AIS standing US spine images, without (measured one time) and with the aid of previous standing radiographs (measured two times). The intra- and interrater reliability, the correlation and the difference between the radiographic and US measurements, and the error index of the end-vertebrae selection were assessed. RESULTS: Overall, 109 curves were investigated. The intraclass correlation coefficients (ICC) of intra- and interrater reliability of the US coronal curvature measurement with the aid of previous radiographs (AOR) were 0.95 and 0.91, respectively. In comparison with the radiographic measurements, the correlation of AOR method (R) was 0.90 and the MAD was 2.8°; the corresponding results of the US measurement without the AOR (blinded US method) were 0.73° and 4.8°, respectively. The average error index on end-vertebral selection improved 43% with the AOR. CONCLUSION: The AOR method significantly improved reliability and accuracy of the spinal curvature measurement on US images compared with the blinded US method (P<0.001). It indicates that US standing images with the AOR can be used as a reliable and accurate nonionizing imaging method to monitor children with AIS. LEVEL OF EVIDENCE: 3.

Predicting success or failure of brace treatment for adolescents with idiopathic scoliosis.

Adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal deformity. Brace treatment is a common non-surgical treatment, intended to prevent progression (worsening) of the condition during adolescence. Estimating a braced patient's risk of progression is an essential part of planning treatment, so method for predicting this risk would be a useful decision support tool for practitioners. This work attempts to discover whether failure of brace treatment (progression) can be predicted at the start of treatment. Records were obtained for 62 AIS patients who had completed brace treatment. Subjects were labeled as "progressive" if their condition had progressed despite brace treatment and "non-progressive" otherwise. Wrapper-based feature selection selected two useful predictor variables from a list of 14 clinical measurements taken from the records. A logistic regression model was trained to classify patients as "progressive" or "non-progressive" using these two variables. The logistic regression model's simplicity and interpretability should facilitate its clinical acceptance. The model was tested on data from an additional 28 patients and found to be 75 % accurate. This accuracy is sufficient to make the predictions clinically useful. It can be used online: http://www.ece.ualberta.ca/~dchalmer/SimpleBracePredictor.html .

Intra- and Inter-rater Reliability of Coronal Curvature Measurement for Adolescent Idiopathic Scoliosis Using Ultrasonic Imaging Method-A Pilot Study.

STUDY DESIGN: Retrospective reliability study of the coronal curvature measurement on ultrasound (US) imaging in adolescent idiopathic scoliosis (AIS). OBJECTIVES: To determine the intra- and inter-rater reliability and validity of the coronal curvature measurements obtained from US images. SUMMARY OF BACKGROUND DATA: Cobb angle measurements on radiographs are the usual method to diagnose and monitor the progression of scoliosis. Repeated ionizing radiation exposure is a frequent concern of patients and their families. Use of US imaging method to measure coronal curvature in children who have idiopathic scoliosis has not been clinically validated. METHODS: The researchers scanned 26 subjects using a medical 3-dimensional US system. Spinal radiographs were obtained on the same day from the local scoliosis clinic. Three raters used the center of lamina method to measure the coronal curvature on the US images twice 1 week apart. The raters also measured the Cobb angle on the radiographs twice. Intra- and inter-rater reliability of the coronal curvature measurement from the US images was analyzed using intra-class correlation coefficients. The correlation coefficient of the US coronal curvature measurements was compared with the Cobb angles. RESULTS: The intra-class correlation coefficient (2,1) values of intra- and inter-rater reliability on the US method were greater than 0.80. Standard error of measurement on both of the intra- and inter-rater US methods was less than 2.8°. The correlation coefficient between the US and radiographic methods ranged between 0.78 and 0.84 among 3 raters. CONCLUSIONS: The US method illustrated substantial intra- and inter-rater reliability. The measurement difference between radiography and the US method was within the range of clinically acceptable error (5°). The US method may be considered a radiation-free alternative to assess children with scoliosis of mild to moderate severity.

rhBMP-2 for posterolateral instrumented lumbar fusion: a multicenter prospective randomized controlled trial.

STUDY DESIGN: Multicenter randomized controlled trial. OBJECTIVE: To evaluate the effect of recombinant human bone morphogenetic protein (rhBMP-2) on radiographical fusion rate and clinical outcome for surgical lumbar arthrodesis compared with iliac crest autograft. SUMMARY OF BACKGROUND DATA: In many types of spinal surgery, radiographical fusion is a primary outcome equally important to clinical improvement, ensuring long-term stability and axial support. Biologic induction of bone growth has become a commonly used adjunct in obtaining this objective. We undertook this study to objectify the efficacy of rhBMP-2 compared with traditional iliac crest autograft in instrumented posterolateral lumbar fusion. METHODS: Patients undergoing 1- or 2-level instrumented posterolateral lumbar fusion were randomized to receive either autograft or rhBMP-2 for their fusion construct. Clinical and radiographical outcome measures were followed for 2 to 4 years postoperatively. RESULTS: One hundred ninety seven patients were successfully randomized among the 8 participating institutions. Adverse events attributable to the study drug were not significantly different compared with controls. However, the control group experienced significantly more graft-site complications as might be expected. 36-Item Short Form Health Survey, Oswestry Disability Index, and leg/back pain scores were comparable between the 2 groups. After 4 years of follow-up, radiographical fusion rates remained significantly higher in patients treated with rhBMP-2 (94%) than those who received autograft (69%) (P = 0.007). CONCLUSION: The use of rhBMP-2 for instrumented posterolateral lumbar surgery significantly improves the chances of radiographical fusion compared with the use of autograft. However, there is no associated improvement in clinical outcome within a 4-year follow-up period. These results suggest that use of rhBMP-2 should be considered in cases where lumbar arthrodesis is of primary concern.

Preservation of motor evoked potentials under anesthesia in children with spinal muscular atrophy type II undergoing spinal deformity surgery.

Spinal muscular atrophy is a progressive condition in which movement is gradually lost as a result of the loss of spinal motor neurons. Individuals with this condition may require surgical correction of a secondary scoliosis. Motor evoked potentials were recorded using transcranial electrical stimulation in four such individuals undergoing surgery. All the patients were nonambulatory and in wheelchairs. Motor evoked potentials were recordable in both upper and lower limb muscles, with similar stimulation parameters to control subjects undergoing surgery for idiopathic scoliosis. The amplitudes of the motor evoked potentials were similar to those in control subjects, although the latencies were shorter reflective of the smaller stature of the spinal muscular atrophy patients. The relative preservation of the motor evoked potentials despite the patients' poor voluntary motor control suggests that there is a selective preservation of the motor neurons mediating the motor evoked potential in spinal muscular atrophy and a maintenance of the conduction velocities of the corticospinal tract.

Smart brace versus standard rigid brace for the treatment of scoliosis: a pilot study.

The outcomes of brace treatment for scoliosis depend on how the brace is used. Simply prescribing a brace does not mean it will be worn properly. A smart brace has been developed to control the brace wear tightness with the expectation that appropriately worn braces will improve outcomes. Twelve brace candidates (10F; 2M) agreed to participate into this study and were randomly divided into 2 groups. The smart brace group used the smart brace for the first year, and then wore the standard brace for the following year. The standard rigid brace group wore their TLSO for 2 years. Both groups were followed for 3 years after they finished the brace treatment. The smart brace group showed better quality of brace wear, wearing their brace at the prescribed tightness level a higher proportion of time than the standard brace group. All subjects in the smart brace group had successful outcomes, Cobb angle changed less than 5°, whereas 2/6 subjects in the standard brace group had unsuccessful bracing. One had 7° increment and 1 underwent surgery. The smart brace group also reported that the smart brace was more comfortable to wear than the standard rigid brace.

Brace wear characteristics during the first 6 months for the treatment of scoliosis.

Bracing is the most commonly used non-surgical treatment for adolescent idiopathic scoliosis (AIS) and requires an extensive commitment on the part of the patient and family. However, demonstrating efficacy of brace treatment for AIS has been hampered by the lack of compressive information about wear characteristics. The first 6 months is considered a critical time to evaluate whether AIS patients will commit to the treatment and may predict the treatment outcome. The characteristics of brace wear can assist clinicians to provide better support and aid long term compliance with treatment. This study describes the first 6 month brace wear characteristics in 15 AIS patients (12F;3M) who were prescribed full-time brace wear. There was a statistically significant increase in wear time (p = 0.02) after brace fitting and the brace wear tightness stabilized after month 4. The force at the major pressure pad area continuously decreased after month 2. A moderate correlation was found between the (quantity * quality) of the brace wear at month 6 and the change of Cobb angle (first out of brace - pre brace) (r2 = 0.47). The more time that the brace was worn and the higher proportion of time worn at the prescribed tightness or above improves the likelihood of a better treatment result.

Pedicle screw insertion in the thoracolumbar spine: comparison of 4 guidance techniques in the intact cadaveric spine.

OBJECT: Pedicle screw fixation is a mainstay of thoracolumbar stabilization. Screw insertion using anatomical landmarks and fluoroscopy is common but can be technically challenging and generally involves substantial exposure to ionizing radiation. Computerized navigation has been reported to improve accuracy but is expensive and complex. The authors undertook this study to evaluate these 3 methods in comparison with a fourth technique using standard cervical distractor screws to mark the entry point and trajectory. METHODS: Four cadaveric human spines were used for this study. After an initial CT scan, 34 pedicle screws were inserted in each intact spine from T-1 to L-5 using the following 4 screw insertion guidance techniques (1 technique per specimen): use of anatomical landmarks, use of cervical distractor screws and spot fluoroscopy, fluoroscopy-based navigation, and fluoroscopy- and CT-based navigation (using merged imaging data). Postprocedural CT and anatomical dissection were then performed to evaluate screw position for site and degree of breach. RESULTS: The cervical distractor screw method had a breach rate of 5.9% versus 29.4%, 32.4%, and 20.6% for use of anatomical landmarks, fluoroscopic navigation, and fluoroscopic-CT navigation, respectively (p < 0.05). There is also a significant association between degree of medial and distal breach and the method of screw insertion (p < 0.05). CONCLUSIONS: Cervical distractor screws as pedicle markers offer favorable insertion accuracy and reduction of radiation exposure compared with the other 3 methods used in clinical practice.

Using ultrasound to guide the insertion of pedicle screws during scoliosis surgery.

Scoliosis surgery involves the insertion of screws and/or hooks into selected vertebrae to secure a pre-bent rod placed along the concave side of the spine. Usually conventional x-rays will be taken before the surgery to plan the alignment and positioning of the pedicle screws. However, reports state that perforation rate range from 6% to 54%. A misalignment of a pedicle screw can potentially cause permanent neurological spinal cord injury or even a life-threatening vascular injury. Because of the importance of positioning and aligning of pedicle screws, we are working on an ultrasound method to guide the insertion of pedicle screws in real time. A pulse-echo immersion experiment was set up to study how well the edges of cortical bone could be detected using a bovine spinous process in-vitro. Two ultrasound frequencies (3.5 MHz and 5.0 MHz) were considered in this study. This preliminary study shows that ultrasound is able to penetrate cortical bone and reflect back from the outer boundary. All interfaces are clearly identified for both frequencies. Strong reflection signals are obtained when the beam is normal to the interface. Derived thickness values from the reflections are comparable with those from micro-CT image. The 5.0 MHz ultrasound frequency provided better resolution than the 3.0 MHz frequency.

The association between Scoliosis Research Society-22 scores and scoliosis severity changes at a clinically relevant threshold.

STUDY DESIGN: Cross-sectional correlation study. OBJECTIVE: To determine the threshold in spinal deformity severity measurements beyond which there is a progressive decline in health-related quality-of-life (HRQOL). SUMMARY OF BACKGROUND DATA: The associations between HRQOL and scoliosis deformity measures are at best moderate when assessed using linear regressions. This may be because HRQOL is not affected until a severity threshold is reached. Identifying the thresholds in deformity beyond which HRQOL deteriorates could assist in treatment recommendations. METHODS: The Scoliosis Research Society-22 (SRS-22) questionnaire was completed by 101 females with adolescent idiopathic scoliosis (age, 15.0 +/- 1.8; largest Cobb angle, 36.9 degrees +/- 14.6 degrees). Radiographs and surface topography were used to quantify the severity of the internal (largest Cobb angle) and external deformity (cosmetic score, decompensation, trunk twist), respectively. Segmented linear regression models were estimated to determine the association between SRS-22 domains and spinal deformity measures. This analysis also identifies deformity thresholds beyond which HRQOL is more affected. The percentage of variance explained (R2) by linear and segmented models were compared (alpha = 0.05) to identify the best models. RESULTS: Cobb angle predicted significantly more variance in all SRS-22 domains except mental health using segmented models (R2: 0.09-0.30) than linear models (R2: 0.02-0.21). Segmented models with a single threshold estimated at a Cobb angle between 43 degrees and 48 degrees predicted between 3% and 11% more variance compared to corresponding linear model using the same variables. Surface topography parameters were not strongly associated with SRS-22 variables with linear and segmented models explaining less than 10% of the variance. CONCLUSION: Deterioration in SRS-22 scores is mildly associated with increases in the severity of the internal deformity. HRQOL is stable until the curve reaches a maximal Cobb angle threshold at approximately 45 degrees where HRQOL declines linearly with increasing internal deformity. The association between HRQOL and scoliosis severity is low, but is better explained by segmented rather than linear models.

Novel fixation technique for the surgical repair of lung hernias.

We describe a novel technique for dealing with the rare complication of post-traumatic or post-thoracotomy lung herniation. The method uses techniques and fixation devices that have been developed for stabilization and fixation of the spine and surgical management of scoliosis. It allows for a secure, reliable, and easily reproducible fixation of the chest-wall in patients with large intercostal lung hernias using standard spinal instruments.

The effect of time on qualitative compliance in brace treatment for AIS.

Brace treatment is the most commonly used non-surgical treatment method for adolescent idiopathic scoliosis (AIS). This study is to determine the force changes exerted by a brace over time during both day and night-time wear and to explore correlations between force changes to bracing outcomes. Twenty subjects (three male, 17 female) diagnosed with idiopathic scoliosis who had worn their braces for six months participated into this study. However, due to non-continuous brace wear and exclusion of subjects with large curves (Cobb angle >40 degrees), only nine subjects were included into the day-time analysis and 11 subjects were included into night-time analysis. All subjects used a load monitor system from four days up to 14 days with Boston braces. Cobb angle measurements were taken at initiation of brace treatment as well as after weaning upon completion of the treatment. After the monitoring period, the data was extracted and analyzed. Forces were compared between hours 1, 2, and 5 for the day and night groups, and the correlation of force changes to bracing outcomes were analyzed. In daytime wear, a significant decrease in force over time was found. Most of the decrease occurred within hours 1 and 2 of brace wear. There was no significant decrease during night wear. There were no significant correlations between force decline and outcome.

Spontaneous spinal epidural hematoma causing Brown-Sequard syndrome: case report and review of the literature.

Spinal epidural hematoma is a rare clinical entity and has a varied etiology. Urgent surgical evacuation to prevent serious permanent neurologic deficits is generally indicated. We describe a case of a 52-year-old man, on oral anticoagulant therapy, who presented with Brown-Sequard syndrome due to spontaneous spinal epidural hematoma at the cervicothoracic junction. This diagnosis was initially overlooked, given the asymmetric pattern of deficit. He later underwent cervical laminectomy and had complete restoration of neurologic function.

Adjunct continuous intravenous ketamine infusion for postoperative pain relief following posterior spinal instrumentation for correction of scoliosis: a case report.

Providing effective analgesia is challenging for correction of idiopathic scoliosis, as nonsteroidal anti-inflammatory drugs and epidural anesthesia are controversial and large-dose opioids can cause significant side effects. Perioperative adjuvant low-dose ketamine has been shown to provide good supplementary analgesia as well as to potentially spare opioid consumption. Ketamine may also improve early ease of mobility without addition of any noticeable adverse effects. This case describes the combined use of a continuous low-dose ketamine infusion and patient-controlled analgesia (PCA) morphine for postoperative analgesia in an adolescent girl undergoing posterior spinal instrumentation and correction of scoliosis. The patient had excellent postoperative analgesia and was able to participate in early rehabilitation. The opioid-sparing effect of ketamine was not demonstrated in this case. Further study of continuous low-dose ketamine infusions in this patient population would be beneficial to provide more evaluation of the efficacy and tolerability of ketamine and of its opioid-sparing potential.