One of the basic tenets of performing surgery is knowledge of the relevant anatomy. Surgeons incorporate this knowledge along with factors, such as biomechanics and physiology, to develop their operative approaches and procedures. In the diagnosis and management of sacral tumors, the need to be familiar with the anatomy of the sacrum is no less important than knowledge of the pathological entity involved. This article will provide an overview of the embryology and anatomy of the sacrum, along with concepts as applied to surgical intervention.
Joseph S. Cheng and John K. Song
Daniel M. Oberer, Oran S. Aaronson and Joseph S. Cheng
✓ The authors describe a previously undocumented complication of suboccipital craniectomy combined with duraplasty for the treatment of Chiari malformation Type I and propose techniques to prevent its occurrence. Although there have been reports of epidural pseudomeningoceles in the setting of spontaneous intracranial hypotension and intracranial hygromas following suboccipital craniectomy with duraplasty, the authors believe this case to be the first instance of quadriparesis caused by the delayed formation of a compressive epidural cerebrospinal fluid collection after suboccipital craniectomy with duraplasty. This complication is significant and must be recognized given the potential severity of neurological insult and the number of these procedures performed yearly in both the pediatric and adult populations.
Joseph F. Cusick, Khang-Cheng Ho and Jay F. Schamberg
✓ Subarachnoid hemorrhage is a frequent finding in patients who have incurred neurological complications following chymopapain chemonucleolysis, but the basis for this occurrence remains controversial. The authors report the clinical and postmortem findings in a 42-year-old man who died 5 days after chemonucleolysis at the L4–5 and L5–S1 disc spaces. The predominant histological abnormality was a severe inflammatory arteritis of a medium-sized artery at the upper cervical level with disruption of the vessel wall. The potential causative role of chymopapain in this situation and the correlation of a vascular basis for many of the complications found after inadvertent intrathecal chymopapain injection are discussed.
Joseph F. Cusick, Khang-Cheng Ho, Thad C. Hagen and Larry E. Kun
✓ Granular-cell pituicytomas of the neurohypophysis have a controversial histogenesis and oncological behavior. The occurrence of such a tumor in a patient whose father and daughter had endocrine neoplasms suggests a neuroectodermal origin for these tumors. Although all of the conditions considered in this report are unusual clinical entities, their correlation offers considerations in understanding the importance of genetic factors in tumor development.
Jonathan A. Forbes, Ahmed J. Awad, Scott Zuckerman, Kevin Carr and Joseph S. Cheng
The authors' goal was to better define the relationship between biomechanical parameters of a helmeted collision and the likelihood of concussion.
The English-language literature was reviewed in search of scholarly articles describing the rotational and translational accelerations observed during all monitored impact conditions that resulted in concussion at all levels of American football.
High school players who suffer concussion experience an average of 93.9g of translational acceleration (TA) and 6505.2 rad/s2 of rotational acceleration (RA). College athletes experience an average of 118.4g of TA and 5311.6 rad/s2 of RA. While approximately 3% of collisions are associated with TAs greater than the mean TA associated with concussion, only about 0.02% of collisions actually result in a concussion. Associated variables that determine whether a player who experiences a severe collision also experiences a concussion remain hypothetical at present.
The ability to reliably predict the incidence of concussion based purely on biomechanical data remains elusive. This study provides novel, important information that helps to quantify the relative insignificance of biomechanical parameters in prediction of concussion risk. Further research will be necessary to better define other factors that predispose to concussion.
Debraj Mukherjee, Kaisorn L. Chaichana, Ziya L. Gokaslan, Oran Aaronson, Joseph S. Cheng and Matthew J. McGirt
Malignant primary osseous spinal neoplasms are aggressive tumors that remain associated with poor outcomes despite aggressive multidisciplinary treatment measures. To date, prognosis for patients with these tumors is based on results from small single-center patient series and controlled trials. Large population-based observational studies are lacking. To assess national trends in histology-specific survival, the authors reviewed patient survival data spanning 30 years (1973–2003) from the Surveillance, Epidemiology, and End Results (SEER) registry, a US population-based cancer registry.
The SEER registry was queried to identify cases of histologically confirmed primary spinal chordoma, chondrosarcoma, osteosarcoma, or Ewing sarcoma using coding from the International Classification of Disease for Oncology, Third Edition. Association of survival with histology, metastasis status, tumor site, and year of diagnosis was assessed using Cox proportional-hazards regression analysis.
A total of 1892 patients were identified with primary osseous spinal neoplasms (414 with chordomas, 579 with chondrosarcomas, 430 with osteosarcomas, and 469 with Ewing sarcomas). Chordomas presented in older patients (60 ± 17 years; p < 0.01) whereas Ewing sarcoma presented in younger patients (19 ± 11 years; p < 0.01) compared with patients with all other tumors. The relative incidence of each tumor type remained similar per decade from 1973 to 2003. African Americans comprised a significantly greater proportion of patients with osteosarcomas than other tumors (9.6% vs 3.5%, respectively; p < 0.01). Compared with the sacrum, the mobile spine was more likely to be the site of tumor location for chordomas than for all other tumors (47% vs 23%, respectively; p < 0.05). Osteosarcoma and Ewing sarcoma were 3 times more likely than chondrosarcoma and chordoma to present with metastasis (31% vs 8%, respectively). Resection was performed more frequently for chordoma (88%) and chondrosarcoma (89%) than for osteosarcoma (61%) and Ewing sarcoma (53%). Overall median survival was histology-specific (osteosarcoma, 11 months; Ewing sarcoma, 26 months; chondrosarcoma, 37 months; chordoma, 50 months) and significantly worse in patients with metastasis at presentation for all tumor types. Survival did not significantly differ as a function of site (mobile spine vs sacrum/pelvis) for any tumor type, but more recent year of diagnosis was associated with improved survival for isolated spinal Ewing sarcoma (hazard ration [HR] 0.95; p = 0.001), chondrosarcoma (HR 0.98; p = 0.009), and chordoma (HR 0.98; p = 0.10), but not osteosarcoma.
In this analysis of a 30-year, US population-based cancer registry (SEER), the authors provide nationally representative prognosis and survival data for patients with malignant primary spinal osseous neoplasms. Overall patient survival has improved for isolated spine tumors with advancements in care over the past 4 decades. These results may be helpful in providing historical controls for understanding the efficacy of new treatment paradigms, patient education, and guiding level of aggressiveness in treatment strategies.
Comparison of cervical spine kinematics using a fluoroscopic model for adjacent segment degeneration
Invited submission from the Joint Section on Disorders of the Spine and Peripheral Nerves, March 2007
Joseph S. Cheng, Fei Liu, Richard D. Komistek, Mohamed R. Mahfouz, Adrija Sharma and Diana Glaser
In this cervical spine kinematics study the authors evaluate the motions and forces in the normal, degenerative, and fused states to assess how alteration in the cervical motion segment affects adjacent segment degeneration and spondylosis.
Fluoroscopic images obtained in 30 individuals (10 in each group with disease at C5–6) undergoing flexion/extension motions were collected. Kinematic data were obtained from the fluoroscopic images and analyzed with an inverse dynamic mathematical model of the cervical spine that was developed for this analysis.
During 20° flexion to 15° extension, average relative angles at the adjacent levels of C6–7 and C4–5 in the fused patients were 13.4° and 8.8° versus 3.7° and 4.8° in the healthy individuals. Differences at C3–4 averaged only about 1°. Maximum transverse forces in the fused spines were two times the skull weight at C6–7 and one times the skull weight at C4–5, compared with 0.2 times the skull weight and 0.3 times the skull weight in the healthy individuals. Vertical forces ranged from 1.6 to 2.6 times the skull weight at C6–7 and from 1.2 to 2.5 times the skull weight at C4–5 in the patients who had undergone fusion, and from 1.4 to 3.1 times the skull weight and from 0.9 to 3.3 times the skull weight, respectively, in the volunteers.
Adjacent-segment degeneration may occur in patients with fusion due to increased motions and forces at both adjacent levels when compared with healthy individuals in a comparable flexion and extension range.
Owoicho Adogwa, Scott L. Parker, David Shau, Stephen K. Mendelhall, Joseph Cheng, Oran Aaronson, Clinton J. Devin and Matthew J. McGirt
The number of low-back fusion procedures for the treatment of spine disorders has increased steadily over the past 10 years. Lumbar pseudarthrosis is a potential complication of lumbar arthrodesis and can be associated with significant pain and disability. The aim of this study was to assess, using validated patient-reported outcomes measures, the long-term effectiveness of revision arthrodesis in the treatment of symptomatic pseudarthrosis.
This is a retrospective study of 47 patients who underwent revision lumbar arthrodesis for pseudarthrosis-associated back pain. Baseline 2-year outcomes were assessed using the following: visual analog scale (VAS) for back pain, Oswestry Disability Index (ODI), Zung Self-Rating Depression Scale, time to narcotic independence, time to return to work, EuroQol health-state utility, and physical and mental quality of life (Short Form [SF]–12 Physical and Mental Component Summary scores).
The mean duration of time between prior fusion and development of symptomatic pseudarthrosis was 2.69 years. Bone morphogenetic protein was used in 4 cases (8.5%) of revision arthrodesis. A significant improvement in VAS back pain (7.31 ± 0.81 vs 5.06 ± 2.64, p = 0.001), ODI (29.74 ± 5.35 vs 25.42 ± 6.0, p = 0.001), and physical health SF-12 (23.83 ± 6.89 vs 27.85 ± 8.90, p = 0.001) scores was observed when comparing baseline and 2-year post–revision arthrodesis scores, respectively, with a mean cumulative 2-year gain of 0.35 quality-adjusted life years. The median time to narcotics independence was 12.16 (interquartile range 1.5–24.0) months and the median time to return to work was 4 months (interquartile range 3–5 months). By 2 years after revision surgery, no patients had experienced pseudarthrosis. The SF-12 Mental Component Summary (44.72 ± 7.90 vs 43.46 ± 7.51, p = 0.43) and Zung Self-Rating Depression Scale scores (39.36 ± 7.48 vs 41.39 ± 10.72, p = 0.37) were not significantly improved by 2 years.
The authors' study suggests that revision lumbar arthrodesis for symptomatic pseudarthrosis provides improvement in low-back pain, disability, and quality of life. Revision lumbar arthrodesis should be considered a viable treatment option for patients with pseudarthrosis-related back pain. Mental health symptoms from pseudarthrosis-associated back pain may be more refractory to revision surgery.
Owoicho Adogwa, Scott L. Parker, David N. Shau, Stephen K. Mendenhall, Clinton J. Devin, Joseph S. Cheng and Matthew J. McGirt
Over the past decade, there has been a dramatic increase in the number of spinal fusions performed in the US and a corresponding increase in the incidence of adjacent-segment disease (ASD). Surgical management of symptomatic ASD consists of decompression of neural elements and extension of fusion. It has been shown to have favorable long-term outcomes, but the cost-effectiveness remains unclear. In this study, the authors set out to assess the cost-effectiveness of revision surgery in the treatment of ASD over a 2-year period.
Fifty patients undergoing neural decompression and extension of fusion construct for ASD-associated back and leg pain were included in the study. Two-year total back-related medical resource utilization, missed work, and health state values (quality-adjusted life years [QALYs], calculated from the EQ-5D with US valuation) were assessed. Two-year resource use was multiplied by unit costs based on Medicare national allowable payment amounts (direct cost), and patient and caregiver workday losses were multiplied by the self-reported gross-of-tax wage rate (indirect cost). Mean total 2-year cost per QALY gained after revision surgery was assessed.
The mean (± SD) interval between prior fusion and revision surgery for ASD was 3.07 ± 2.02 years. A mean cumulative 2-year gain of 0.76 QALYs was observed after revision surgery. The mean total 2-year cost of extension of fusion constructs was $47,846 ± $32,712 (surgery cost: $24,063 ± $300; outpatient resource utilization cost: $4175 ± $3368; indirect cost: $19,607 ± $32,187). Revision decompression and extension of fusion was associated with a mean 2-year cost per QALY gained of $62,955.
In the authors' practice, revision decompression and extension of fusion provided a significant gain in health state utility for patients with symptomatic ASD, with a 2-year cost per QALY gained of $62,995. When indicated, revision surgery for ASD is a valuable treatment option for patients experiencing back and leg pain secondary to ASD. The findings provide a value measure of surgery that can be compared with future cost-per-QALY-gained studies of medical management or alternative surgical approaches.
Kaisorn L. Chaichana, Debraj Mukherjee, Owoicho Adogwa, Joseph S. Cheng and Matthew J. McGirt
Lumbar discectomy is the most common surgical procedure performed in the US for patients experiencing back and leg pain from herniated lumbar discs. However, not all patients will benefit from lumbar discectomy. Patients with certain psychological predispositions may be especially vulnerable to poor clinical outcomes.
The goal of this study was therefore to determine the role that preoperative depression and somatic anxiety have on long-term back and leg pain, disability, and quality of life (QOL) for patients undergoing single-level lumbar discectomy.
In 67 adults undergoing discectomy for a single-level herniated lumbar disc, the authors determined quantitative measurements of leg and back pain (visual analog scale [VAS]), quality of life (36-Item Short Form Health Survey [SF-36]), and disease-specific disability (Oswestry Disability Index) preoperatively and at 6 weeks, 3, 6, and 12 months after surgery. The degree of preoperative depression and somatization was assessed using the Zung Self-Rating Depression Scale and a modified somatic perception questionnaire (MSPQ). Multivariate regression analyses were performed to assess associations between Zung Scale and MSPQ scores with achievement of a minimum clinical important difference (MCID) in each outcome measure by 12 months postoperatively.
All patients completed 12 months of follow-up. Overall, a significant improvement in VAS leg pain, VAS back pain, Oswestry Disability Index, and SF-36 Physical Component Summary scores was observed by 6 weeks after surgery. Improvements in all outcomes were maintained throughout the 12-month follow-up period. Increasing preoperative depression (measured using the Zung Scale) was associated with a decreased likelihood of achieving an MCID in disability (p = 0.006) and QOL (p = 0.04) but was not associated with VAS leg pain (p = 0.96) or back pain (p = 0.85) by 12 months. Increasing preoperative somatic anxiety (measured using the MSPQ) was associated with decreased likelihood of achieving an MCID in disability (p = 0.002) and QOL (p = 0.03) but was not associated with leg pain (p = 0.64) or back pain (p = 0.77) by 12 months.
The Zung Scale and MSPQ are valuable tools for stratifying risk in patients who may not experience clinically relevant improvement in disability and QOL after discectomy. Efforts to address these confounding and underlying contributors of depression and heightened somatic anxiety may improve overall outcomes after lumbar discectomy.