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Devon Hoover, Aruna Ganju, Christopher I. Shaffrey, Henry Bartkowski and Michael J. Rauzzino

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Christopher B. T. Adams, Michael R. Fearnside and Sean A. O'Laoire

✓ Serial postoperative angiograms were performed in 28 patients with intracranial aneurysms, 26 of whom had presented with a subarachnoid hemorrhage. The clinical state and intracranial pressure (ICP) were also measured. Angiograms were performed in the ward using a cannula, which was passed into the proximal external carotid artery via the superficial temporal artery. Measurements of the vessel diameters were made, with the preoperative angiogram as a baseline. Patients could be placed into one of five groups depending on the presence or absence of significant arterial spasm, the clinical state of the patient, and the normality or otherwise of the ICP. No patient's condition deteriorated without an elevated ICP and/or significant arterial spasm. The study shows that this spasm is usually associated with a poor clinical state if it reaches a maximum 8 to 12 hours after the operation, although the clinical deterioration is not apparent for a further 6 to 12 hours. Knowledge of the natural history of postoperative arterial spasm may allow earlier treatment of the spasm, which may be more successful than delaying treatment until clinical deterioration has occurred. The worth of the varied drugs proposed for the treatment of spasm may be assessed using this type of protocol.

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Shivanand P. Lad, Chirag G. Patil, Christopher Ho, Michael S. B. Edwards and Maxwell Boakye

Object

Previous investigations of health outcome after spinal surgery for tethered cord syndrome (TCS) have been single-institution studies. The aim of this study was to report inpatient complications and outcomes on a nationwide level.

Methods

The Nationwide Inpatient Sample (NIS) was used to identify patients who underwent spinal surgery for TCS in the US between 1993 and 2002. Patients who had a primary diagnosis of TCS (ICD-9 742.59) and also underwent spinal laminectomies were included in this study. Multivariate analysis was performed to analyze the effects of patient and hospital characteristics on variables such as mortality rate, nonfatal complications, LOS, and adverse outcomes in general (defined as death or discharge to an institution rather than home).

Results

The NIS sample included data on 9733 patients with TCS who underwent surgery. The means for mortality rate, complication rate, and LOS, respectively, were 0.0005%, 9.48%, and 5.6 days. Postoperative hemorrhages or hematomas (mean rate 2.3%) were the most common complications reported. Age and complications were the only significant predictors of adverse outcome on multivariate analysis. Patients older than 65 years had a threefold increase in risk of adverse outcome compared with patients 18 to 44 years of age. On average, one postoperative complication led to a 3-day increase in mean LOS and added more than $9000 to hospital charges.

Conclusions

This study provides a national perspective on inpatient complications and outcomes after spinal surgery for TCS in the United States. The authors have demonstrated the impact of age, complications, and medical comorbidities on the outcome of surgery for patients with this common disorder.

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Avital Perry, Thomas J. Sorenson, Christopher S. Graffeo, Colin L. Driscoll and Michael J. Link

Cavernous malformations (CMs) are low-pressure, focal, vascular lesions that may occur within the brainstem and require treatment, which can be a substantial challenge. Herein, we demonstrate the surgical resection of a hemorrhaged brainstem CM through a posterior petrosectomy approach. After dissection of the overlying vascular and meningeal structures, a safe entry zone into the brainstem is identified based on local anatomy and intraoperative neuronavigation. Small ultrasound probes can also be useful for obtaining real-time intraoperative feedback. The CM is internally debulked and resected in a piecemeal fashion through an opening smaller than the CM itself. As brainstem CMs are challenging lesions, knowledge of several surgical nuances and adoption of careful microsurgical techniques are requisite for success.

The video can be found here: https://youtu.be/szB6YpzkuCo.

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Michael M. Safaee, Cecilia L. Dalle Ore, Corinna C. Zygourakis, Vedat Deviren and Christopher P. Ames

OBJECTIVE

Proximal junctional kyphosis (PJK) is a well-recognized complication of surgery for adult spinal deformity and is characterized by increased kyphosis at the upper instrumented vertebra (UIV). PJK prevention strategies have the potential to decrease morbidity and cost by reducing rates of proximal junctional failure (PJF), which the authors define as radiographic PJK plus clinical sequelae requiring revision surgery.

METHODS

The authors performed an analysis of 195 consecutive patients with adult spinal deformity. Age, sex, levels fused, upper instrumented vertebra (UIV), use of 3-column osteotomy, pelvic fixation, and mean time to follow-up were collected. The authors also reviewed operative reports to assess for the use of surgical adjuncts targeted toward PJK prevention, including ligament augmentation, hook fixation, and vertebroplasty. The cost of surgery, including direct and total costs, was also assessed at index surgery and revision surgery. Only revision surgery for PJF was included.

RESULTS

The mean age of the cohort was 64 years (range 25–84 years); 135 (69%) patients were female. The mean number of levels fused was 10 (range 2–18) with the UIV as follows: 2 cervical (1%), 73 upper thoracic (37%), 108 lower thoracic (55%), and 12 lumbar (6%). Ligament augmentation was used in 99 cases (51%), hook fixation in 60 cases (31%), and vertebroplasty in 71 cases (36%). PJF occurred in 18 cases (9%). Univariate analysis found that ligament augmentation and hook fixation were associated with decreased rates of PJF. However, in a multivariate model that also incorporated age, sex, and UIV, only ligament augmentation maintained a significant association with PJF reduction (OR 0.196, 95% CI 0.050–0.774; p = 0.020). Patients with ligament augmentation, compared with those without, had a higher cost of index surgery, but ligament augmentation was overall cost effective and produced significant cost savings. In sensitivity analyses in which we independently varied the reduction in PJF, cost of ligament augmentation, and cost of reoperation by ± 50%, ligament augmentation remained a cost-effective strategy for PJF prevention.

CONCLUSIONS

Prevention strategies for PJK/PJF are limited, and their cost-effectiveness has yet to be established. The authors present the results of 195 patients with adult spinal deformity and show that ligament augmentation is associated with significant reductions in PJF in both univariate and multivariate analyses, and that this intervention is cost-effective. Future studies will need to determine if these clinical results are reproducible, but for high-risk cases, these data suggest an important role of ligament augmentation for PJF prevention and cost savings.

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Christopher B. Shields and Michael West

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Michael P. Kelly, Lawrence G. Lenke, Jakub Godzik, Ferran Pellise, Christopher I. Shaffrey, Justin S. Smith, Stephen J. Lewis, Christopher P. Ames, Leah Y. Carreon, Michael G. Fehlings, Frank Schwab and Adam L. Shimer

OBJECTIVE

The authors conducted a study to compare neurological deficit rates associated with complex adult spinal deformity (ASD) surgery when recorded in retrospective and prospective studies. Retrospective studies may underreport neurological deficits due to selection, detection, and recall biases. Prospective studies are expensive and more difficult to perform, but they likely provide more accurate estimates of new neurological deficit rates.

METHODS

New neurological deficits were recorded in a prospective study of complex ASD surgeries (pSR1) with a defined outcomes measure (decrement in American Spinal Injury Association lower-extremity motor score) for neurological deficits. Using identical inclusion criteria and a subset of participating surgeons, a retrospective study was created (rSR1) and neurological deficit rates were collected. Continuous variables were compared with the Student t-test, with correction for multiple comparisons. Neurological deficit rates were compared using the Mantel-Haenszel method for standardized risks. Statistical significance for the primary outcome measure was p < 0.05.

RESULTS

Overall, 272 patients were enrolled in pSR1 and 207 patients were enrolled in rSR1. Inclusion criteria, defining complex spinal deformities, and exclusion criteria were identical. Sagittal Cobb measurements were higher in pSR1, although sagittal alignment was similar. Preoperative neurological deficit rates were similar in the groups. Three-column osteotomies were more common in pSR1, particularly vertebral column resection. New neurological deficits were more common in pSR1 (pSR1 17.3% [95% CI 12.6–22.2] and rSR1 9.0% [95% CI 5.0–13.0]; p = 0.01). The majority of deficits in both studies were at the nerve root level, and the distribution of level of injury was similar.

CONCLUSIONS

New neurological deficit rates were nearly twice as high in the prospective study than the retrospective study with identical inclusion criteria. These findings validate concerns regarding retrospective cohort studies and confirm the need for and value of carefully designed prospective, observational cohort studies in ASD.

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Michael P. Kelly, Michael A. Kallen, Christopher I. Shaffrey, Justin S. Smith, Douglas C. Burton, Christopher P. Ames, Virginie Lafage, Frank J. Schwab, Han Jo Kim, Eric O. Klineberg, Shay Bess and the International Spine Study Group

OBJECTIVE

After using PROsetta Stone crosswalk tables to calculate Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) and Pain Interference (PI) scores, the authors sought to examine 1) correlations with Scoliosis Research Society–22r (SRS-22r) scores, 2) responsiveness to change, and 3) the relationship between baseline scores and 2-year follow-up scores in adult spinal deformity (ASD).

METHODS

PROsetta Stone crosswalk tables were used to converted SF-36 scores to PROMIS scores for pain and physical function in a cohort of ASD patients with 2-year follow-up. Spearman correlations were used to evaluate the relationship of PROMIS scores with SRS-22r scores. Effect size (ES) and adjusted standardized response mean (aSRM) were used to assess responsiveness to change. Linear regression was used to evaluate the association between baseline scores and 2-year follow-up scores.

RESULTS

In total, 425 (425/625, 68%) patients met inclusion criteria. Strong correlations (all |r| > 0.7, p < 0.001) were found between baseline and 2-year PROMIS values and corresponding SRS-22r domain scores. PROMIS-PI showed a large ES (1.09) and aSRM (0.88), indicating good responsiveness to change. PROMIS-PF showed a moderate ES (0.52) and moderate aSRM (0.69), indicating a moderate responsiveness to change. Patients with greater baseline pain complaints were associated with greater pain improvement at 2 years for both SRS-22r Pain (B = 0.39, p < 0.001) and PROMIS-PI (B = 0.45, p < 0.001). Higher functional scores at baseline were associated with greater average improvements in both SRS-22r Activity (B = 0.62, p < 0.001) and PROMIS-PF (B = 0.40, p < 0.001).

CONCLUSIONS

The authors found strong correlations between the SRS-22r Pain and Activity domains with corresponding PROMIS-PI and -PF scores. Pain measurements showed similar and strong ES and aSRM while the function measurements showed similar, moderate ES and aSRM at 2-year follow-up. These data support further exploration of the use of PROMIS–computer adaptive test instruments in ASD.

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Gregory C. Wiggins, Michael J. Rauzzino, Christopher I. Shaffrey, Russ P. Nockels, Richard Whitehill, Mark E. Shaffrey, James Wagner and Tord D. Alden

This study was conducted to determine the safety, efficacy, and complication rate associated with the anterior approach in the use of a new titanium mesh interbody fusion cage for the treatment of unstable thoracolumbar burst fractures. The experience with this technique is compared with the senior authors' (C.S., R.W., and M.S.) previously published results in the management of patients with unstable thoracolumbar burst fractures.

Between 1996 and 1999, 21 patients with unstable thoracolumbar (T12-L3) burst fractures underwent an anterolateral decompressive procedure in which a titanium cage and Kaneda device were used. Eleven of the 21 patients had sustained a neurological deficit, and all patients improved at least one Frankel grade (average 1.2 grades). There was improvement in outcome in terms of blood loss, correction of kyphosis, and pain, as measured on the Denis Pain and Work Scale, in our current group of patients treated via an anterior approach when compared with the results in those who underwent a posterior approach.

In our current study the anterior approach was demonstrated to be a safe and effective technique for the management of unstable thoracolumbar burst fractures. It offers superior results compared with the posterior approach. The addition of the new titanium mesh interbody cage to our previous anterior technique allows the patient's own bone to be harvested from the corpectomy site and used as a substrate for fusion, thereby obviating the need for iliac crest harvest. The use of the cage in association with the Kaneda device allows for improved correction of kyphosis and restoration of normal sagittal alignment in addition to improved functional outcomes.

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Michael Safaee, Andrew T. Parsa, Nicholas M. Barbaro, Dean Chou, Praveen V. Mummaneni, Philip R. Weinstein, Tarik Tihan and Christopher P. Ames

OBJECT

Intradural extramedullary spine tumors represent two-thirds of all primary spine neoplasms. Approximately half of these are peripheral nerve sheath tumors, mainly neurofibromas and schwannomas. Given the rarity of this disease and, thus, the limited analyses of clinical outcomes, the authors examined the association of tumor location, extent of resection, and neurofibromatosis (NF) status with clinical outcomes.

METHODS

Patients were identified through a search of the University of California, San Francisco, neuropathology database and a separate review of current procedural terminology codes. Data recorded included patient age, patient sex, clinical presentation, presence of NF, tumor type, tumor location, extent of resection (gross-total resection [GTR] or subtotal resection [STR]), and clinical follow-up.

RESULTS

Of 221 tumors in 199 patients (mean age 45 years), 53 were neurofibromas, 163 were schwannomas, and 5 were malignant peripheral nerve sheath tumors. The most common presenting symptom was spinal pain (76%), followed by weakness (36%) and sensory abnormalities (34%). Mean symptom duration was 16 months. In terms of spinal location, neurofibromas were more common in the cervical spine (74% vs 27%, p < 0.001), and schwannomas were more common in the thoracic and lumbosacral spine (73% vs 26%, p < 0.001). Rates of GTR were lower for neurofibromas than schwannomas (51% vs 83%, p < 0.001), regardless of location. Rates of GTR were lower for cervical (54%) than thoracic (90%) and lumbosacral (86%) lesions (p < 0.001). NF was associated with lower rates of GTR among all tumors (43% vs 86%, p < 0.001). The mean follow-up time was 32 months. Recurrence/progression was more common for neurofibromas than schwannomas (17% vs 7%, p = 0.03), although the mean time to recurrence/progression did not differ according to tumor type (45 vs 53 months, p = 0.63). As expected, GTR was associated with lower recurrence rates (4% vs 22%, p < 0.001). According to multivariate analysis, cervical location (OR 0.239, 95% CI 0.110–0.520) and presence of NF (OR 0.166, 95% CI 0.054–0.507) were associated with lower rates of GTR. In a separate model, only GTR (OR 0.141, 95% CI 0.046–0.429) was associated with tumor recurrence.

CONCLUSIONS

Resection is an effective treatment for spinal nerve sheath tumors. Neurofibromas were found more commonly in the cervical spine than in other regions of the spine and were associated with higher rates of recurrence and lower rates of GTR than other tumor types, particularly in patients with NF Types 1 or 2. According to multivariate analysis, both cervical location and presence of NF were associated with lower rates of GTR. According to a second multivariate model, the only variable associated with tumor recurrence was extent of resection. Maximal safe resection remains ideal for these lesions; however, patients with cervical tumors or NF should be counseled about their increased risk for recurrence.