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Editorial

Infantile idiopathic scoliosis

Mark F. Abel

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Steven W. Hwang, Amer F. Samdani and Patrick J. Cahill

Object

Idiopathic scoliosis is a pathological process influencing the spinal column in 3 dimensions. Initial surgical treatment focused primarily on correction in the coronal plane, and with improved instrumentation, increasing attention has targeted balancing the sagittal profile. Newer surgical techniques now permit operative corrective forces to also directly address axial rotation. Although several technical variations of direct vertebral body derotation (DVBD) have been devised, no studies have compared outcomes from the differing techniques. The purpose of this study was to describe and compare the differences between segmental and en bloc DVBD.

Methods

A large prospectively collected database was queried for patients with adolescent idiopathic scoliosis (AIS) who underwent posterior spinal fusion and for whom there was a minimum of 2 years of follow-up. In all patients some type of DVBD maneuver was performed (segmental, en bloc, or both). Any patients with concurrent thoracoplasties were excluded.

Results

The authors identified 188 patients, of whom 120 underwent segmental derotation, 17 en bloc derotation, and 51 both. No significant radiographic or clinical differences existed among the groups preoperatively. The mean preoperative thoracic curve in the entire cohort was 53.1° ± 14.1° and the mean thoracic rib prominence was 14.0° ± 5.5°, whereas the respective postoperative values were 19.3° ± 8.3° and 7.2° ± 4.0°. No significant difference was identified between the various techniques postoperatively, either. However, when comparing intraoperative variables, significant differences were found for operative duration (p = 0.0001), estimated blood loss (p = 0.0081), and volume of blood transfusions (p = 0.041).

Conclusions

Although each surgical technique of DBVD may have theoretical benefits and risks, no apparent difference in outcomes was observed between techniques. The concurrent use of both techniques was associated with increased blood loss and operative duration without any appreciable benefit. The surgeon should adopt the derotation technique with which he or she is most comfortable, but concurrent use of both does not appear to improve results.

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Ali A. Baaj, Douglas Brockmeyer, Andrew Jea and Amer F. Samdani

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Maria Zuccaro, James Zuccaro, Amer F. Samdani, Joshua M. Pahys and Steven W. Hwang

OBJECTIVE

Intraoperative neuromonitoring (IONM) involves the use of somatosensory evoked potentials (SSEPs) and transcranial electric motor evoked potentials (TceMEPs). In this retrospective study the authors examined the sensitivity and specificity of both SSEPs and TceMEPs during pediatric spinal deformity surgeries.

METHODS

The authors performed a retrospective quantitative analysis of data obtained in 806 patients (197 males and 609 females) treated from December 2011 until October 2015. All patients were diagnosed with scoliosis that was classified as one of the following: adolescent idiopathic scoliosis (AIS) (38%), congenital scoliosis (22%), or syndromic scoliosis (40%). Also, 53 patients underwent vertebral column resection (VCR). All surgeries were monitored by high-level neuromonitoring specialists and were performed with total intravenous anesthesia. Alerts were described as a decrease in amplitude by 50% or greater (bilateral or unilateral) in SSEPs, TceMEPs, or both.

RESULTS

True-positive alerts for TceMEPs were observed in 60 of the 806 patients (7.4%). True-positive alerts for SSEPs were observed in 7 of the 806 patients (0.9%). In contrast, there were no false-positive or false-negative outcomes. Only 1 case (0.1%) was reported with a permanent postoperative deficit. No reported false negatives or false positives were observed, and thus sensitivity was 100% and specificity was 93%–100% for TceMEPs. The rate of sensitivity was 13.2% and the rate of specificity was 100% for SSEPs. The breakdown of total alert was as follows: 6.6% in AIS cases, 24.5% in congenital scoliosis cases, and 10.2% in syndromic scoliosis cases. Neurological injury rates were significantly lower than in previous studies, as there were 0% for AIS cases (p = 0.12), 0.6% for congenital scoliosis cases (p = 0.17), and 0% for syndromic scoliosis cases (p = 0.07). One injury in a patient with congenital scoliosis occurred during a VCR procedure, which brought the injury rate to 1.9% (p < 0.005). IONM alerts occurred during 34% of rod/correction cases, 25% of thoracic screw placements, 20% of the osteotomies, 17% of the resections, 3% of the cage insertions, and 2% of the sublaminar wiring procedures.

CONCLUSIONS

The authors hypothesize that the results of this study will support the necessity, as a standard of care, of multimodality neuromonitoring during high-risk pediatric spinal deformity surgery because of the decrease in postoperative deficits. Their data suggest that the TceMEPs are more sensitive than SSEPs, but when used in combination, they offer the patient a level of safety that would otherwise not exist. Last, these findings support the notion that better outcomes are achieved with high-level IONM professionals.

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Brandon J. Toll, Amer F. Samdani, M. Burhan Janjua, Shashank Gandhi, Joshua M. Pahys and Steven W. Hwang

OBJECTIVE

High rates of perioperative complications are associated with deformity correction in neuromuscular scoliosis. The current study aimed to evaluate complications associated with surgical correction of neuromuscular scoliosis and to characterize potential risk factors.

METHODS

Data were retrospectively collected from a single-center cohort of 102 consecutive patients who underwent spinal fusions for neuromuscular scoliosis between January 2008 and December 2016 and who had a minimum of 6 months of follow-up. A subgroup analysis was performed on data from patients who had at least 2 years of follow-up. Univariate and multivariate regression analyses, as well as binary correlational models and Student t-tests, were employed for further statistical analysis.

RESULTS

The present cohort had 53 boys and 49 girls with a mean age at surgery of 14.0 years (± 2.7 SD, range 7.5–19.5 years). The most prevalent diagnoses were cerebral palsy (26.5%), spinal cord injury (24.5%), and neurofibromatosis (10.8%). Analysis reflected an overall perioperative complication rate of 27% (37 complications in 27 patients), 81.1% of which constituted major complications (n = 30) compared to a rate of 18.9% for minor complications (n = 7). Complications were predicted by nonambulatory status (p = 0.037), increased intraoperative blood loss (p = 0.012), increased intraoperative time (p = 0.046), greater pelvic obliquity at follow-up (p = 0.028), and greater magnitude of sagittal profile at follow-up (p = 0.048). Pulmonary comorbidity (p = 0.001), previous operations (p = 0.013), history of seizures (p = 0.046), diagnosis of myelomeningocele (p = 0.046), increase in weight postoperatively (p < 0.005), and increased lumbar lordosis at follow-up (p = 0.015) were identified as risk factors for perioperative infection.

CONCLUSIONS

These results suggest that in neuromuscular scoliosis, patients with preexisting pulmonary compromise and greater intraoperative blood loss have the greatest risk of experiencing a major perioperative complication following surgical deformity correction.

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Joseph Ferguson, Steven W. Hwang, Zachary Tataryn and Amer F. Samdani

Object

Intraoperative monitoring of the spinal cord has become the standard of care during surgery for pediatric spinal deformity correction. The use of both somatosensory and motor evoked potentials has dramatically increased the sensitivity and specificity of detecting intraoperative neurophysiological changes to the spinal cord, which assists in the intraoperative decision-making process. The authors report on a large, single-center experience with neuromonitoring changes and outline the surgical management of patients who experience significant neuromonitoring changes during spinal deformity correction surgery.

Methods

The authors conducted a retrospective review of all cases involving pediatric patients who underwent spinal deformity correction surgery at Shriners Hospital for Children, Philadelphia, between January 2007 and March 2010. Five hundred nineteen consecutive cases were reviewed in which neuromonitoring was used, with 47 cases being identified as having significant changes in somatosensory evoked potentials, motor evoked potentials, or both. These cases were reviewed for patient demographic data and surgical characteristics.

Results

The incidence of significant neuromonitoring changes was 9.1% (47 of 519 cases), including 6 cases of abnormal Stagnara wake-up tests, of which 4 had corroborated postoperative neurological deficits (8.5% of 47 cases, 0.8% of 519). In response to neuromonitoring changes, wake-up tests were performed in 37 (79%) of 47 cases, hardware was adjusted in 15 (32%), anesthesiology interventions were reported in 5 (11%), hardware was removed in 5 (11%), the patient was successfully repositioned in 3 (6%), and the procedure was aborted in 13 (28%). In 1 of the 4 patients with new postoperative deficits, the deficit had fully resolved by the last follow-up; the other 3 patients had persistent neurological impairment as of the most recent follow-up examination. The authors observed a sensitivity of 100% for intraoperative neuromonitoring.

Conclusions

Due to the profound risks associated with spinal deformity surgery, intraoperative neurophysiological monitoring is an integral tool to warn of impending spinal cord injury. Intraoperative neuromonitoring appears to provide a safe and useful warning mechanism to minimize spinal cord injury that may arise during scoliosis correction surgery in pediatric patients.

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Daniel J. Cognetti, Amer F. Samdani, Joshua M. Pahys, Mari L. Groves and Steven W. Hwang

Growing rod surgery for skeletally immature patients helps correct severe scoliosis while allowing continued spinal column growth. Previous reports have studied vertebral body changes following growing rod surgery, but there are currently no published reports on alterations in pedicle morphology. Given the potential need for definitive spinal fusion with pedicle screw instrumentation, an awareness of changes in pedicle morphology is critical. A morphometric analysis of pedicles was performed using 3D reconstructions of 3 CT scans (preoperative and at 3 and 6 years) obtained in a young girl with infantile idiopathic scoliosis (T7 apex) who underwent unilateral rib-to-spine growing rod (2nd–4th ribs to L1) implantation with lengthening every 6 months for 6 years. The pedicle widths on the growing rod side from T5 to T9 (apex ± 2) were all smaller at 6 years postoperatively than preoperatively, while the same-level pedicles opposite the device significantly increased in width. These findings support anecdotal intraoperative reports by surgeons and provide evidence of pedicle stress shielding due to growing rod distraction and force deprivation.

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Steven W. Hwang, Ornella M. Dubaz, Robert Ames, Alex Rothkrug, Jeff S. Kimball and Amer F. Samdani

Object

The thoracic rib hump, caused by axial rotation of the spine, is one of the most dissatisfying cosmetic features associated with adolescent idiopathic scoliosis (AIS). However, advances in instrumentation and surgical techniques, such as direct vertebral body derotation (DVBD), have allowed improved correction in the axial plane and the rib hump. In cases of thoracolumbar/lumbar curves (Lenke Type 5), the lumbar prominence can be equally disfiguring and is often associated with waist asymmetry, another cosmetic concern. Although DVBD has been evaluated in the thoracic spine, little is known about its impact on the lumbar spine. The authors investigated the outcomes of DVBD on the lumbar prominence.

Methods

A prospectively collected multicenter database was queried for pediatric patients with AIS and Lenke Type 5 curves. All patients who underwent thoracoplasty procedures were excluded. A total of 34 patients underwent surgical correction via a posterior-only approach using pedicle screw constructs. Nineteen patients underwent concurrent DVBD, and the remaining 15 patients served as a control group and did not undergo DVBD. All patients had a minimum of 2 years of follow-up.

Results

The mean age of the entire cohort was 14.9 ± 2.3 years, and the majority of patients were female (88%). All patients had Lenke Type 5C curves with a mean major curve of 46.0° ± 8.7°, which corrected to 13.7° ± 7.2° (70% correction). A mean of 10.7 ± 3.0 levels were fused. Only thoracic kyphosis was significantly different between the groups preoperatively. Similarly, postoperative radiographic parameters were comparable between the groups, with equivalent percentages of correction. Although improvement in the thoracic rib hump was comparable between the groups, the DVBD group had 56.2% correction of the lumbar prominence, and the control group had 76% improvement (p = 0.05).

Conclusions

Although DVBD has been a valuable tool in the management of AIS, the authors' results suggest that its application for thoracolumbar curves may be limited. Further analysis with a larger cohort is required to better ascertain the impact of DVBD on thoracolumbar curves.

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Shabbar F. Danish, Amer Samdani, Amgad Hanna, Phillip Storm and Leslie Sutton

Object

Posterior fossa decompression with duraplasty is routinely used for the treatment of Chiari malformations. It has been traditionally believed that this procedure requires a watertight seal with primary closure of the dura with either pericranium or allograft. In this study, the authors evaluated two synthetic dural substitutes in this patient population for feasibility of use and identification of perioperative morbidity.

Methods

The authors evaluated 56 patients who underwent duraplasty with a synthetic collagen matrix (Dura-Gen) after suboccipital craniectomy and C-1 laminectomy, and 45 patients in whom the dural closure involved acellular human dermis (AlloDerm). Patients in both groups were assessed for the presence of a pseudomeningocele, wound infection, cerebrospinal fluid (CSF) leak, and the need for repeated operation either for wound revision or the placement of a ventriculoperitoneal shunt. Operative times for which DuraGen duraplasty was used were compared with those for AlloDerm closure.

In the DuraGen group, complications included five pseudomeningoceles (8.9%), two wound infections (3.6%), one CSF leak (1.8%), and four repeated operations (three shunt revisions and one reexploration; 7.1%) in nine patients. In the AlloDerm group, there were five pseudomeningoceles (11.1%), one wound infection (2.2%), one CSF leak (2.2%), and two repeated operations (two shunt revisions; 4.4%) in seven patients. The operative time associated with DuraGen was significantly shorter than that of duraplasty that required closure with sutures (92 minutes compared with 128 minutes, p < 0.01).

Conclusions

The synthetic dural substitutes DuraGen and AlloDerm provide a suitable alternative duraplasty with comparable complication rates. DuraGen requires a significantly shorter operative time than AlloDerm.