Factor analysis of the SRS-22 outcome assessment instrument in patients with adult spinal deformity.

PURPOSE: Designed for patients with adolescent idiopathic scoliosis, the SRS-22 is now widely used as an outcome instrument in patients with adult spinal deformity (ASD). No studies have confirmed the four-factor structure (pain, function, self-image, mental health) of the SRS-22 in ASD and under different contexts. Factorial invariance of an instrument over time and in different languages is essential to allow for precise interpretations of treatment success and comparisons across studies. This study sought to evaluate the invariance of the SRS-22 structure across different languages and sub-groups of ASD patients. METHODS: Confirmatory factor analysis was performed on the 20 non-management items of the SRS-22 with data from 245 American English-, 428 Spanish-, 229 Turkish-, 95 French-, and 195 German-speaking patients. Item loading invariance was compared across languages, age groups, etiologies, treatment groups, and assessment times. A separate sample of SRS-22 data from 772 American surgical patients with ASD was used for cross-validation. RESULTS: The factor structure fitted significantly better to the proposed four-factor solution than to a unifactorial solution. However, items 14 (personal relationships), 15 (financial difficulties), and 17 (days off work) consistently showed weak item loading within their factors across all language versions and in both baseline and follow-up datasets. A trimmed SRS (16 non-management items) that used the four least problematic items in each of the four domains yielded better-fitting models across all languages, but equivalence was still not reached. With this shorter version there was equivalence of item loading with respect to treatment (surgery vs conservative), time of assessment (baseline vs 12 months follow-up), and etiology (degenerative vs idiopathic), but not age (< vs ≥50 years). All findings were confirmed in the cross-validation sample. CONCLUSION: We recommend removal of the worst-fitting items from each of the four domains of the SRS-instrument (items 3, 14, 15, 17), together with adaptation and standardization of other items across language versions, to provide an improved version of the instrument with just 16 non-management items.

Treatment of metastatic prostate cancer of the spine.

There is a wide spectrum of presentations for prostate cancer metastatic to the spine. Important factors are the patient's age and general health; the extent and location of spinal involvement; the patient's neurologic status and degree of pain; the relative contribution of a blastic or lytic response; and the experience and training of the spinal surgeon, medical oncologist, and radiation oncologist. The spine is both a weight-bearing structure and a housing for the spinal cord, and failure to consider both functions may lead to unsatisfactory treatment results. Treatment options include hormonal therapy, inhibitors of bone metabolism, glucocorticoid therapy, radiotherapy, halo-vest, surgical debridement, decompression and stabilization, and appropriate pain management and support. One must not lose sight of the fact that the goals are palliation and that ultimate demise is unavoidable in patients with metastatic prostate cancer.

Principles and imaging of spinal instrumentation.

This articles focuses on the principles of spinal surgery, the basic types of spinal instrumentation, and imaging of the postoperative spine. It is the first of three articles in this issue that discuss the spine. Complications are discussed and illustrated throughout. This article should assist radiologists in the review of spinal, chest, and abdominal films of spinal surgery patients.

Fixation techniques and instrumentation used in the cervical spine.

This article emphasizes the techniques and instrumentation used in the cervical spine to provide insight into the identification and function of the fixation, grafting, and wiring techniques used for stabilization and fusion. Fracture reduction and stabilization in degenerative disease, the most common reasons for spinal fixation in the cervical spine, are discussed, as are infections, spinal stenosis, and tumors.

Fixation techniques and instrumentation used in the thoracic, lumbar, and lumbosacral spine.

The radiologist is faced with continual changes in both surgical techniques and instrumentation for the spine. To properly evaluate radiographic and special imaging studies, it is necessary to have a working knowledge of the devices used and the principles that direct their use. This article discusses the identification and function of the most common instrumentation in the thoracic, lumbar, and lumbosacral spine.

Radiographic results of arthrodesis with Cotrel-Dubousset instrumentation for the treatment of adolescent idiopathic scoliosis. A five to ten-year follow-up study.

We evaluated the radiographic results of posterior spinal arthrodesis with use of Cotrel-Dubousset instrumentation in seventy-six patients who had adolescent idiopathic scoliosis. At an average of six years (range, five to ten years) postoperatively, the fusion appeared to be solid in all patients. Comparison of radiographs that had been made immediately postoperatively with those that had been made at the time of the latest follow-up showed that no patient had lost any correction in the coronal plane at the levels with instrumentation and seventy-five had had no change in the thoracic or lumbar sagittal alignment at the levels with or without instrumentation. In the remaining patient, a kyphosis had developed at the junction of the segments with instrumentation and those without instrumentation, necessitating additional operative treatment. Sixty-three patients completed a questionnaire for assessment of the clinical status. Their responses were favorable with regard to function, cosmetic appearance, and general satisfaction with the operative result. Twenty-four (38 per cent) of the sixty-three patients reported occasional pain in the spine that did not interfere with work or school activities. Sixty-two patients stated that, given the hypothetical situation of reverting to the preoperative status, they would have the operation again.

Cotrel-Dubousset instrumentation for adolescent idiopathic scoliosis.

We evaluated the results of segmental fixation of the spine with Cotrel-Dubousset instrumentation in ninety-five patients who had adolescent idiopathic scoliosis. The instrumentation was used in an attempt to achieve three-dimensional correction of the scoliosis, maintain lumbar lordosis, create thoracic kyphosis, and avoid the need for a postoperative cast or brace. The patients were followed for twenty-four to sixty-four months (average, thirty-five months). Cotrel-Dubousset instrumentation provided an average correction of the coronal curve of 48 per cent at the time of the most recent follow-up. The normal sagittal curves at the thoracolumbar junction and in the lumbar spine were maintained, and the thoracic kyphosis was increased slightly (average, +7 degrees). Apical translation improved an average of 60 per cent, and apical rotation improved an average of 11 per cent. Forced vital capacity improved an average of 21 per cent, and the one-second forced expiratory volume improved an average of 18 per cent. There were no major neurological deficits. A symptomatic pseudarthrosis developed in one patient. Postoperatively, decompensation of the spine developed in five of the first twenty-six patients who had a Type-II or Type-III curve. This complication was avoided in the last twenty-four patients who had a Type-II or Type-III curve by means of a stricter adherence to the definition of a Type-II curve, and reversal of the bend of the rod and the hooks between the caudal neutral and stable vertebrae. The major advantages of Cotrel-Dubousset instrumentation are the stable fixation that is achieved and the preservation of segmental lumbar lordosis.

Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis.

BACKGROUND: The lack of a reliable, universally acceptable system for classification of adolescent idiopathic scoliosis has made comparisons between various types of operative treatment an impossible task. Furthermore, long-term outcomes cannot be determined because of the great variations in the description of study groups. METHODS: We developed a new classification system with three components: curve type (1 through 6), a lumbar spine modifier (A, B, or C), and a sagittal thoracic modifier (-, N, or +). The six curve types have specific characteristics, on coronal and sagittal radiographs, that differentiate structural and nonstructural curves in the proximal thoracic, main thoracic, and thoracolumbar/lumbar regions. The lumbar spine modifier is based on the relationship of the center sacral vertical line to the apex of the lumbar curve, and the sagittal thoracic modifier is based on the sagittal curve measurement from the fifth to the twelfth thoracic level. A minus sign represents a curve of less than +10 degrees, N represents a curve of 10 degrees to 40 degrees, and a plus sign represents a curve of more than +40 degrees. Five surgeons, members of the Scoliosis Research Society who had developed the new system and who had previously tested the reliability of the King classification on radiographs of twenty-seven patients, measured the same radiographs (standing coronal and lateral as well as supine side-bending views) to test the reliability of the new classification. A randomly chosen independent group of seven surgeons, also members of the Scoliosis Research Society, tested the reliability and validity of the classification as well. RESULTS: The interobserver and intraobserver kappa values for the curve type were, respectively, 0.92 and 0.83 for the five developers of the system and 0.740 and 0.893 for the independent group of seven scoliosis surgeons. In the independent group, the mean interobserver and intraobserver kappa values were 0.800 and 0.840 for the lumbar modifier and 0.938 and 0.970 for the sagittal thoracic modifier. These kappa values were all in the good-to-excellent range (>0.75), except for the interobserver reliability of the independent group for the curve type (kappa = 0.74), which fell just below this level. CONCLUSIONS: This new two-dimensional classification of adolescent idiopathic scoliosis, as tested by two groups of surgeons, was shown to be much more reliable than the King system. Additional studies are necessary to determine the versatility, reliability, and accuracy of the classification for defining the vertebrae to be included in an arthrodesis.

Intraobserver and interobserver reliability of the classification of thoracic adolescent idiopathic scoliosis.

The system described by King et al. is the standard method for the classification of thoracic adolescent idiopathic scoliosis. Although it is widely used and referenced, its reliability and reproducibility among scoliosis surgeons are unknown. We used a scoliosis case-presentation format to examine the interobserver and intraobserver reliability of the classification of thoracic adolescent idiopathic scoliosis with the system of King et al. Eight active, current members of the Scoliosis Research Society reviewed twenty-seven full-length radiographs that had been made before operative correction of the scoliotic deformity. On the basis of these images, which included posteroanterior and lateral radiographs made with the patient standing as well as right and left forced-side-bending radiographs made with the patient supine, the reviewers assigned a type to each curve according to the classification system of King et al. Kappa coefficients were used to test statistical reliability. The mean interobserver reliability of the classification was only 64 per cent (range, 54 to 77 per cent) when the responses of seven of the reviewers were compared with those of one of the originators of the classification. The mean kappa coefficient was 0.49 (range, 0.27 to 0.73), which indicates poor reliability. When each reviewer's responses were compared with those of the other reviewers, the reliability was similarly poor (interobserver reliability, 55 per cent [range, 33 to 81 per cent] and mean kappa coefficient, 0.40 [range, 0.21 to 0.63]). Intraobserver reliability was evaluated in a trial in which five reviewers in a group setting were shown the same radiographs in a different order at two different viewings. Comparison of the results at the two viewings revealed a mean intraobserver reliability of 69 per cent (range, 56 to 85 per cent) and a mean kappa coefficient of 0.62 (range, 0.34 to 0.95), which indicates fair reliability. The current method of classification of adolescent idiopathic scoliosis does not appear to have sufficient intraobserver or interobserver reliability among scoliosis surgeons to portray curve types accurately. Thus, it may not help to guide treatment with use of modern spinal fixation methods.

The effect of nerve-root injections on the need for operative treatment of lumbar radicular pain. A prospective, randomized, controlled, double-blind study.

BACKGROUND: The purpose of the present study was to determine the effectiveness of selective nerve-root injections in obviating the need for an operation in patients with lumbar radicular pain who were otherwise considered to be operative candidates. Although selective nerve-root injections are used widely, we are not aware of any prospective, randomized, controlled, double-blind studies demonstrating their efficacy. METHODS: Fifty-five patients who were referred to four spine surgeons because of lumbar radicular pain and who had radiographic confirmation of nerve-root compression were prospectively randomized into the study. All of the patients had to have requested operative intervention and had to be considered operative candidates by the treating surgeon. They then were randomized and referred to a radiologist who performed a selective nerve-root injection with either bupivacaine alone or bupivacaine with betamethasone. The treating physicians and the patients were blinded to the medication. The patients were allowed to choose to receive as many as four injections. The treatment was considered to have failed if the patient proceeded to have the operation, which he or she could opt to do at any point in the study. RESULTS: Twenty-nine of the fifty-five patients, all of whom had initially requested operative treatment, decided not to have the operation during the follow-up period (range, thirteen to twenty-eight months) after the nerve-root injections. Of the twenty-seven patients who had received bupivacaine alone, nine elected not to have the operation. Of the twenty-eight patients who had received bupivacaine and betamethasone, twenty decided not to have the operation. The difference in the operative rates between the two groups was highly significant (p < 0.004). CONCLUSIONS: Our data demonstrate that selective nerve-root injections of corticosteroids are significantly more effective than those of bupivacaine alone in obviating the need for a decompression for up to thirteen to twenty-eight months following the injections in operative candidates. This finding suggests that patients who have lumbar radicular pain at one or two levels should be considered for treatment with selective nerve-root injections of corticosteroids prior to being considered for operative intervention.

Surgical treatment of adolescent idiopathic scoliosis: the basics and the controversies.

Decisions about when to operate should be based on more than just an arbitrary Cobb measurement. The patient's skeletal maturity, balance, and other parameters of curve size also should be considered. Although it is desirable to fuse as few segments as possible, there is no benefit to fusing short if the top and bottom of the fusion is not neutral and stable. Especially for lumbar fusions, the last instrumented vertebra must be stable, neutral, and horizontal to the sacrum postoperatively. Many thoracic/lumbar curve patterns are Type II (false double major) and not double major curves. They often can be treated with selective thoracic fusion. However, many variables are involved, and the potential for decompensation should be discussed with the patient and the patient's family so they know that it may be necessary to later add the lumbar curve. The rod rotation maneuver and anterior segmental spinal instrumentation often may save fusion levels over what may have been needed with Harrington instrumentation. However, there are many variables here as well. Surgeons should be particularly concerned with maintaining and re-creating enough segmental lordosis for the patient so the spine can withstand the inevitable aging process.

Segmental analysis of the sagittal plane alignment of the normal thoracic and lumbar spines and thoracolumbar junction.

Recent advances in spinal instrumentation have brought about a new emphasis on the three-dimensional spinal deformity of scoliosis and especially on the restoration of normal sagittal plane contours. Normal alignment in the coronal and transverse planes is easily defined; however, normal sagittal plane alignment is not so simple. This retrospective study was undertaken to increase the understanding of the normal alignment of the spine in the sagittal plane, with a special emphasis on the thoracolumbar junction. Measurements were made from the lateral radiographs of 102 subjects with clinically and radiographically normal spines. Cobb measurements of the thoracic kyphosis (T3-T12), the thoracolumbar junction (T10-T12 and T12-L2), and the lumbar lordosis (L1-L5) were determined. The spices of the thoracic kyphosis and lumbar lordosis also were determined. Using a computerized digitalizing table, the segmental angulation was determined at each level from T1-2 to L5-S1. In conclusion, there is a wide range of normal sagittal alignment of the thoracic and lumbar spines. When using composite measurements of the combined frontal and sagittal plane deformity of scoliosis, this wide range of sagittal variance should be taken into consideration. Using norms established here for segmental alignment, areas of hypokyphosis and hypolordosis commonly seen in scoliosis can be more objectively evaluated. The thoracolumbar junction is for all practical purposes straight; lumbar lordosis usually starts at L1-2 and gradually increases at each level caudally to the sacrum.

Incidence of neural axis abnormalities in infantile and juvenile patients with spinal deformity. Is a magnetic resonance image screening necessary?

STUDY DESIGN: A prospective and retrospective review of patients 10 years and younger with idiopathic scoliosis evaluated with a total spine magnetic resonance imaging (MRI) scan. OBJECTIVES: To determine the incidence of neural axis abnormalities in infantile and juvenile patients with idiopathic scoliosis without neurologic findings on history and examination, to determine the need for a screening MRI in this age group. SUMMARY OF BACKGROUND DATA: In previous studies, a 19.2% and 26% incidence of neural axis abnormalities were found in infantile and juvenile patients with "idiopathic" scoliosis, respectively, raising the question of routine MRI screening of the spinal canal in these patients. METHODS: A prospective study included 34 consecutive patients newborn to 10 years of age treated between 1992 and 1996 at a spinal deformity clinic with idiopathic scoliosis > 20 degrees without neurologic findings. In addition, a retrospective review of 64 patients age newborn to 10 years of age with idiopathic scoliosis was performed. All patients were evaluated by a total spine MRI protocol for examination of neural axis abnormalities. RESULTS: The incidence of neural axis abnormalities in the prospective group of 34 patients was 17.6% (6 of 34); the incidence of neural axis abnormalities was 20.3% (13 of 64) in the retrospective group. Of 6 patients in the infantile age range, 3 (50%) had neural axis abnormalities. CONCLUSIONS: A total spine MRI is recommended at presentation in patients with juvenile onset idiopathic scoliosis (> 20 degrees) because of the high incidence of neural axis abnormalities. Further study appears warranted to establish the incidence of neural axis abnormalities in infantile idiopathic scoliosis to determine the need for total spine MRI screening in this age group.

Relationship among level of distraction, evoked potentials, spinal cord ischemia and integrity, and clinical status in animals.

Somatosensory evoked potentials (SEPs) and neurogenic-motor evoked potentials (NMEPs) were recorded after overdistraction of the spinal cord at T5-T6, T12-L1, or L3-L4. Measures of spinal cord perfusion and clinical status were also administered. Results indicated that stiffer spinal segments allowed less distraction than more flexible segments. SEPs and NMEPs were lost quickly after overdistraction in stiff segments and slowly in more flexible segments. However, SEPs were less sensitive than NMEPs to effects from overdistraction. Spinal cord perfusion and integrity were consistent with reduced perfusion and structural damage after overdistraction in stiff segments; extremely reduced perfusion but no structural changes in more flexible segments. The application of these results to the clinical situation was provided.

Analysis of pulmonary function and chest cage dimension changes after thoracoplasty in idiopathic scoliosis.

STUDY DESIGN: A prospective study of 19 adolescents and seven adults with idiopathic scoliosis undergoing posterior spinal fusion with segmental spinal instrumentation and a concomitant thoracoplasty had pulmonary function evaluation before surgery and at selected time points up to a minimum 2 years after surgery. OBJECTIVES: The objectives were to determine the effects thoracoplasty had on pulmonary function and chest cage dimension changes at a minimum 2-year follow-up in idiopathic scoliosis patients. SUMMARY OF BACKGROUND DATA: The cosmetic benefits of thoracoplasty on the rib hump deformity are well accepted. The rib resection procedure allowed for procurement of autogenous bone used for the arthrodesis. Short- and long-term pulmonary function evaluation was necessary to determine proper patient selection and any potential sequelae from the rib resection procedure. METHODS: All patients had pulmonary function tests consisting of forced vital capacity, forced expiratory volume in 1 second, and total lung capacity performed before surgery and 3 months, 1 year, and 2 years after surgery. Ten adolescents also had computed tomographic scans before and after surgery to evaluate chest cage dimension changes after the procedure. RESULTS: The 3-month postoperative pulmonary function test values of the 19 adolescents experienced a statistically significant decline, averaging 16% (P < 0.05), however, the mean values for each parameter returned to just slightly below the preoperative value at 2-years follow-up. The pulmonary function test values of the seven adults experienced a 27% initial decline 3 months after surgery and a residual 23% decline 2 years after surgery; both values were statistically significant (P < 0.05). CONCLUSIONS: We reserve the thoracoplasty procedure for adolescents and adults with preoperative pulmonary function values that will tolerate the morbidity associated with the rib resection. Adolescent patients appear to normalize their pulmonary function tests by 2 years follow-up, whereas long-term pulmonary function in the adult patient remains a concern.

Prospective analysis of nutritional status normalization after spinal reconstructive surgery.

STUDY DESIGN: A prospective analysis of nutritional status after surgery in 57 spinal reconstructive surgery patients. OBJECTIVES: To determine the length of time required for patients to return to their preoperative nutritional baseline and to investigate risk factors for patients with prolonged normalization. SUMMARY OF BACKGROUND DATA: The preoperative nutritional status of spinal reconstructive surgery patients appears to be an important parameter of surgical morbidity, complication rates (especially wound healing), patient acceptance, and overall surgical success. METHODS: The nutritional parameters of albumin, pre-albumin, total protein, transferrin, and the absolute lymphocyte count were investigated before surgery and at various time points after surgery. RESULTS: Forty-four patients (Group A) with an average 6.4 fusion levels returned to their preoperative baseline nutritional values by 6 weeks after surgery, whereas 13 patients (Group B) with a statistically increased number of fusion levels of 13.8 (P = 0.0009) took 12 weeks or longer to return to their preoperative baseline. Risk factors for prolonged normalization (Group B) included increased total number of fusion levels, especially 10 or more (P < 0.05); patients undergoing circumferential fusions (P < 0.05); and, to a lesser extent, older patients undergoing multiple fusion levels (P = 0.055). CONCLUSIONS: These data are important when counseling spinal reconstructive surgery patients before surgery and provides information to those patients who may benefit from perioperative nutritional supplementation.

Magnetic stimulation of the spine to produce lower extremity EMG responses. Significance of coil position and the presence of bone.

STUDY DESIGN: Magnetic stimulation of the spinal cord in 14 pigs was performed, and compound muscle action potentials (CMAPs) were recorded from lower extremities before and after nerve root and spinal cord lesioning. OBJECTIVES: The authors determined whether magnetic stimulation of the spinal cord produced lower extremity CMAPs. SUMMARY OF BACKGROUND DATA: Previous studies indicated that the magnetic stimulation of the spinal cord would result in lower extremity CMAP if appropriate amounts of spinal bone were removed to expose the spinal cord. RESULTS: Our findings demonstrated that the presence of intervening bone did not affect the reliability or presence of lower extremity CMAPs. Additionally, magnetic stimulation did not result in spinal cord activation but produced activity in nerve roots lateral to nerve root foramen. Lesioning of the spinal cord and complete rhizotomies did not affect magnetically elicited CMAPs. CONCLUSIONS: Magnetic stimulation of the spinal canal does not result in activation of spinal cord motor tracts. Lower extremity CMAPs were elicited by stimulation of nerve roots lateral to nerve root foramen and not of the spinal cord. Magnetic stimulation of the spinal cord is not appropriate for monitoring spinal cord motor tract function.

Innervation pattern of dorsal roots and their effects on the specificity of dermatomal somatosensory evoked potentials.

Dermatomal somatosensory evoked potentials are used to monitor individual nerve root function during degenerative spinal surgery. However, a less than 100% agreement between level(s) of dermatomal somatosensory evoked potentials abnormality and nerve root involvement has been reported. The purpose of this article was to determine the possible cause of this discrepancy. Results from humans suggest that variations in peripheral innervation patterns of the dorsal nerve roots are the main reason for dermatomal somatosensory evoked potentials discrepancy both for cervical and lumbar nerve roots. Because these variations cannot be controlled, the authors recommend that dermatomal somatosensory evoked potentials and additional neurophysiologic methods be used during degenerative surgeries to provide the surgeon with information about individual nerve root function. A patient profile for these methods was provided.

Effects of distraction on physiologic integrity of the spinal cord, spinal cord blood flow, and clinical status.

The authors determined the effects of distraction of the spine on physiologic integrity of the spinal cord using neurogenic motor evoked potentials (NMEPs), somatosensory evoked potentials (SEPs), spinal cord blood flow measurements, and clinical status in nine hogs. Spinal cord blood flow was measured after each level of distraction using the hydrogen washout technique. The results indicated that blood flow of at least 65% of baseline was required to maintain physiologic integrity of the spinal cord, and that a decrease of blood flow to 12% of baseline was associated with paraplegia. Neurogenic motor evoked potentials always correlated with the animal's postsurgical clinical status, whereas the SEP was falsely negative in one animal.

Major intraoperative neurologic deficits in pediatric and adult spinal deformity patients. Incidence and etiology at one institution.

STUDY DESIGN: A retrospective study of 1,090 patients undergoing corrective spinal deformity surgery for scoliosis (n = 920), kyphosis (n = 77), or a combination of the two (n = 93) at one institution. OBJECTIVES: To ascertain the etiologies and incidence of neurologic deficits occurring at the time of surgery. SUMMARY OF BACKGROUND DATA: Potential etiologies of intraoperative neurologic deficits include cord compression, overdistraction, purely vascular, or a combination. METHODS: The study group included only patients with useful function of their lower extremities and normal bowel and bladder control, and patients whose surgeries were in spinal cord territory as opposed to purely cauda equina territory. RESULTS: There were four major neurologic deficits that occurred during surgery. Three of the four deficits were purely vascular in etiology. The fourth may have had a vascular and mechanical etiology. All four patients had anterior and posterior surgery with harvesting of the unilateral convex segmental vessels, and each had a component of hyperkyphosis, as well as intraoperative controlled hypotension. All four patients showed marked improvement of motor weakness with time. CONCLUSIONS: Significant risk factors were combined anterior and posterior surgery (P = 0.009) and hyperkyphosis (P = 0.0006).