Surgical management of malignant melanotic nerve sheath tumors: an institutional experience and systematic review of the literature.

OBJECTIVE: Malignant melanotic nerve sheath tumors are rare tumors characterized by neoplastic melanin-producing Schwann cells. In this study, the authors report their institution's experience in treating spinal and peripheral malignant melanotic nerve sheath tumors and compare their results with the literature. METHODS: Data were collected from 8 patients who underwent surgical treatment for malignant melanotic nerve sheath tumors between 1996 and 2023 at Mayo Clinic and 63 patients from the literature. Time-to-event analyses were performed for the combined group of 71 cases to evaluate the risk of recurrence, metastasis, and death based on tumor location and type of treatment received. Unpaired 2-sample t-tests and Fisher's exact tests were used to determine statistical significance between groups. RESULTS: Between 1996 and 2023, 8 patients with malignant melanotic nerve sheath tumors underwent surgery at the authors' institution, while 63 patients were identified in the literature. The authors' patients and those in the literature had the same mean age at diagnosis (43 years). At the authors' institution, 5 patients (63%) experienced metastasis, 6 patients (75%) experienced long-term recurrence, and 5 patients (62.5%) died. In the literature, most patients (60.3%) were males, with a peak incidence between the 4th and 5th decades of life. Nineteen patients (31.1%) were diagnosed with Carney complex. Nerve root tumors accounted for most presentations (n = 39, 61.9%). Moreover, 24 patients (38.1%) had intradural lesions, with 54.2% (n = 13) being intramedullary and 45.8% (n = 11) extramedullary. Most patients underwent gross-total resection (GTR) (n = 41, 66.1%), followed by subtotal resection (STR) (n = 12, 19.4%), STR with radiation therapy (9.7%), and GTR with radiation therapy (4.8%). Sixteen patients (27.6%) experienced metastasis, 23 (39.7%) experienced recurrence, and 13 (22%) died. Kaplan-Meier analyses showed no significant differences among treatment approaches in terms of recurrence-free, metastasis-free, and overall survival (p > 0.05). Similar results were obtained when looking at the differences with respect to intradural versus nerve root location of the tumor (p > 0.05). CONCLUSIONS: Malignant melanotic nerve sheath tumors are rare tumors with a high potential for malignancy. They carry a dismal prognosis, with a pooled local recurrence rate of 42%, distant metastasis rate of 27%, and mortality rate of 26%. The findings from this study suggest a trend favoring the use of GTR alone or STR with radiation therapy over STR alone. Mortality was similar regardless, which highlights the need for the development of effective treatment options to improve survival in patients with melanotic schwannomas.

C1-C2 Posterior Screw-Rod Fixation.

Multiple approaches for instrumentation of the upper cervical spine have evolved to treat atlantoaxial instability which, until the 20th century, was largely considered to be inoperable and managed nonsurgically with immobilization. Surgeons set out to provide safe and effective approaches in a clearly dangerous and technically complex anatomic region. It is important to provide a historical analysis of the evolution of techniques that have shaped C1-C2 instrumentation, and how the diligent efforts of surgeons to improve the biomechanical stability and fusion rates of their constructs eventually led to the prevailing Harms technique. This technique is explored by describing its surgical steps, alternative techniques, and associated outcomes. For successful instrumentation of the atlantoaxial joint, a comprehensive understanding of spinal biomechanics, surgical techniques, and anatomic variations is imperative for surgeons to develop a tailored plan for each patient's individual pathology and anatomy.

Paraspinal Sarcopenia is Associated With Worse Patient-Reported Outcomes Following Laminoplasty for Degenerative Cervical Myelopathy.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The present study is the first to assess the impact of paraspinal sarcopenia on patient-reported outcome measures (PROMs) following cervical laminoplasty. BACKGROUND: While the impact of sarcopenia on PROMs following lumbar spine surgery is well-established, the impact of sarcopenia on PROMs following laminoplasty has not been investigated. METHODS: We performed a retrospective review of patients undergoing laminoplasty from C4-6 at a single institution between 2010 and 2021. Two independent reviewers utilized axial cuts of T2-weighted magnetic resonance imaging sequences to assess fatty infiltration of the bilateral transversospinales muscle group at the C5-6 level and classify patients according to the Fuchs Modification of the Goutalier grading system. PROMs were then compared between subgroups. RESULTS: We identified 114 patients for inclusion in this study, including 35 patients with mild sarcopenia, 49 patients with moderate sarcopenia, and 30 patients with severe sarcopenia. There were no differences in preoperative PROMs between subgroups. Mean postoperative neck disability index scores were lower in the mild and moderate sarcopenia subgroups (6.2 and 9.1, respectively) than in the severe sarcopenia subgroup (12.9, P =0.01). Patients with mild sarcopenia were nearly twice as likely to achieve minimal clinically important difference (88.6 vs. 53.5%; P <0.001) and six times as likely to achieve SCB (82.9 vs. 13.3%; P =0.006) compared with patients with severe sarcopenia. A higher percentage of patients with severe sarcopenia reported postoperative worsening of their neck disability index (13 patients, 43.3%; P =0.002) and Visual Analog Scale Arm scores (10 patients, 33.3%; P =0.03). CONCLUSION: Patients with severe paraspinal sarcopenia demonstrate less improvement in neck disability and pain postoperatively and are more likely to report worsening PROMs following laminoplasty. LEVEL OF EVIDENCE: 3.

Semispinalis Cervicis Sarcopenia is Associated With Worsening Cervical Sagittal Balance and Junctional Alignment Following Posterior Cervical Fusion for Myelopathy.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: The present study is the first to investigate whether cervical paraspinal sarcopenia is associated with cervicothoracic sagittal alignment parameters after posterior cervical fusion (PCF). SUMMARY OF BACKGROUND DATA: Few studies have investigated the association between sarcopenia and postoperative outcomes after cervical spine surgery. METHODS: We retrospectively reviewed patients undergoing PCF from C2-T2 at a single institution between the years 2017-2020. Two independent reviewers utilized axial cuts of T2-weighted magnetic resonance imaging sequences to perform Goutallier classification of the bilateral semispinalis cervicis (SSC) muscles. Cervical sagittal alignment parameters were compared between subgroups based upon severity of SSC sarcopenia. RESULTS: We identified 61 patients for inclusion in this study, including 19 patients with mild SSC sarcopenia and 42 patients with moderate or severe SSC sarcopenia. The moderate-severe sarcopenia subgroup demonstrated a significantly larger change in C2-C7 sagittal vertical axis (+6.8 mm) from the 3-month to 1-year postoperative follow-up in comparison to the mild sarcopenia subgroup (-2.0 mm; P =0.02). The subgroup of patients with moderate-severe sarcopenia also demonstrated an increase in T1-T4 kyphosis (10.9-14.2, P =0.007), T1 slope (28.2-32.4, P =0.003), and C2 slope (24.1-27.3, P =0.05) from 3-month to 1-year postoperatively and a significant decrease in C1-occiput distance (6.3-4.1, P =0.002) during this same interval. CONCLUSIONS: In a uniform cohort of patients undergoing PCF from C2-T2, SSC sarcopenia was associated with worsening cervicothoracic alignment from 3-month to 1-year postoperatively.

En bloc resection of a high cervical chordoma followed by reconstruction with a free vascularized fibular graft: illustrative case.

BACKGROUND: Wide excision of chordoma provides better local control than intralesional resection or definitive radiotherapy. The en bloc excision of high cervical chordomas is a challenging endeavor because of the complex anatomy of this region and limited reconstructive options. OBSERVATIONS: This is the first case report to describe reconstruction with a free vascularized fibular graft following the en bloc excision of a chordoma involving C1-3. LESSONS: This report demonstrates the durability of this construct at 10-year follow-up and is the first case report demonstrating satisfactory long-term oncological outcomes after a true margin-negative resection of a high cervical chordoma.

At Mean 30-Year Follow-Up, Cervical Spine Disease Is Common and Associated with Thoracic Hypokyphosis after Pediatric Treatment of Adolescent Idiopathic Scoliosis.

Patients with adolescent idiopathic scoliosis (AIS) often have reduced sagittal thoracic kyphosis (hypokyphosis) and cervical lordosis causing an uneven distribution of physiologic load. However, the long-term consequences of hypokyphosis in AIS patients have not been previously documented. To evaluate whether uneven load distribution leads to future complications in patients with AIS, we conducted a retrospective chart review and subsequently surveyed 180 patients treated for idiopathic scoliosis between 1975 and 1992. These patients all had a minimum follow-up time of 20 years since their treatment. We observed a ten-fold increase in the incidence of anterior cervical discectomy and fusion (ACDF) compared to reported rates in the non-pathologic population. Out of the 180 patients, 33 patients met the criteria and returned for follow-up radiographs. This population demonstrated a statistically significant increased rate of cervical osteoarthritis and disc degeneration. Overall, our study suggests that hypokyphosis in patients with AIS presents with increased rates of cervical spine degeneration and dysfunction, suggesting that these patients may require additional follow-up and treatment.

Multifidus Sarcopenia Is Associated With Worse Patient-reported Outcomes Following Posterior Cervical Decompression and Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The present study is the first to assess the impact of paraspinal sarcopenia on patient-reported outcome measures (PROMs) following posterior cervical decompression and fusion (PCDF). SUMMARY OF BACKGROUND DATA: While the impact of sarcopenia on PROMs following lumbar spine surgery is well-established, the impact of sarcopenia on PROMs following PCDF has not been investigated. MATERIALS AND METHODS: We performed a retrospective review of patients undergoing PCDF from C2 to T2 at a single institution between the years 2017 and 2020. Two independent reviewers who were blinded to the clinical outcome scores utilized axial cuts of T2-weighted magnetic resonance imaging sequences to assess fatty infiltration of the bilateral multifidus muscles at the C5-C6 level and classify patients according to the Fuchs Modification of the Goutalier grading system. PROMs were then compared between subgroups. RESULTS: We identified 99 patients for inclusion in this study, including 28 patients with mild sarcopenia, 45 patients with moderate sarcopenia, and 26 patients with severe sarcopenia. There was no difference in any preoperative PROM between the subgroups. Mean postoperative Neck Disability Index scores were lower in the mild and moderate sarcopenia subgroups (12.8 and 13.4, respectively) than in the severe sarcopenia subgroup (21.0, P <0.001). A higher percentage of patients with severe multifidus sarcopenia reported postoperative worsening of their Neck Disability Index (10 patients, 38.5%; P =0.003), Visual Analog Scale Neck scores (7 patients, 26.9%; P =0.02), Patient-Reported Outcome Measurement Information System Physical Component Scores (10 patients, 38.5%; P =0.02), and Patient-Reported Outcome Measurement Information System Mental Component Scores (14 patients, 53.8%; P =0.02). CONCLUSION: Patients with more severe paraspinal sarcopenia demonstrate less improvement in neck disability and physical function postoperatively and are substantially more likely to report worsening PROMs postoperatively. LEVEL OF EVIDENCE: 3.

Does Preoperative Bone Mineral Density Impact Fusion Success in Anterior Cervical Spine Surgery? A Prospective Cohort Study.

OBJECTIVE: The purpose of this study was to identify risk factors for pseudarthrosis in patients undergoing anterior cervical discectomy and fusion (ACDF) with a focus on the role of bone mineral density (BMD) on arthrodesis. METHODS: We retrospectively reviewed a prospectively collected database of patients undergoing 1- to 4-level ACDF for degenerative indications between 2012 and 2018 at a single institution. All patients were required to have undergone a preoperative dual-energy x-ray absorptiometry (DEXA) scan. Fusion status was assessed on computed tomography (CT) scans obtained 1 year postoperatively. Patients were divided into subgroups based on fusion status and compared on the basis of demographic, BMD, and surgical variables to determine risk factors for pseudarthrosis. RESULTS: We identified 79 patients for inclusion in this study. Fusion was achieved in 65 patients (82%), while 14 patients (18%) developed pseudarthrosis. The pseudarthrosis subgroup demonstrated significantly lower BMD than their counterparts who achieved successful fusion in both mean hip (-1.4 ± 1.2 vs. -0.2 ± 1.2, respectively; P = 0.002) and spine T-scores (-0.8 ± 1.8 vs. 0.6 ± 1.9, respectively; P = 0.02). The pseudarthrosis group had a substantially higher proportion of patients with osteopenia (57.1% vs. 20.0%) and osteoporosis (21.5% vs. 6.2%; P < 0.001) than the fusion group. Multivariate analysis demonstrated osteopenia (odds ratio [OR] 8.76, P = 0.04), osteoporosis (OR 9.97, P = 0.03), and low BMD (OR 11.01, P = 0.002) to be associated with an increased likelihood of developing pseudarthrosis. CONCLUSIONS: The results of this study suggest that both osteopenia and osteoporosis are associated with increased rates of pseudarthrosis in patients undergoing elective ACDF.

Cervical myelopathy in a patient with Klippel-Feil syndrome treated with a patient-specific custom cervical spine locking plate.

INTRODUCTION: Klippel-Feil Syndrome is the congenital fusion of at least two cervical vertebrae. Often asymptomatic, though in rare cases it may lead to severe cervical spine deformity and neurologic injury. CASE PRESENTATION: We report a case of a 48-year-old woman with a history of Klippel-Feil Syndrome and congenital scoliosis who developed progressive cervical myelopathy. She was surgically treated with anterior C5 corpectomy and arthrodesis. Pre-operative evaluation was facilitated by 3D printed models. The surgical decompression and spinal reconstruction was completed with the use of a patient-specific, custom-made cervical spine locking plate. DISCUSSION: Pre-operative evaluation with 3D printing technology was useful in understanding the patient's complex curve pattern and in designing a patient specific implant. Custom designed implant is a reasonable option to treat cervical myelopathy associated with complex cervical deformity.

Average Lumbar Hounsfield Units Predicts Osteoporosis-Related Complications Following Lumbar Spine Fusion.

STUDY DESIGN: Retrospective Study. OBJECTIVE: To compare methods of assessing pre-operative bone density to predict risk for osteoporosis related complications (ORC), defined as proximal junctional kyphosis, pseudarthrosis, accelerated adjacent segment disease, reoperation, compression fracture, and instrument failure following spine fusions. METHODS: Chart review of primary posterior thoracolumbar or lumbar fusion patients during a 7 year period. Inclusion criteria: preoperative dual-energy x-ray absorptiometry (DXA) test within 1 year and lumbar CT scan within 6 months prior to surgery with minimum of 1 year follow-up. Exclusion criteria: <18 years at time of index procedure, infection, trauma, malignancy, skeletal dysplasia, neuromuscular disorders, or anterior-posterior procedures. RESULTS: 140 patients were included. The average age was 67.9 years, 83 (59.3%) were female, and 45 (32%) had an ORC. There were no significant differences in patient characteristics between those with and without an ORC. Multilevel fusions were associated with ORCs (46.7% vs 26.3%, p = 0.02). Patients with ORCs had lower DXA t-scores (-1.62 vs -1.10, p = 0.003) and average Hounsfield units (HU) (112.1 vs 148.1, p ≤ 0.001). Multivariable binary logistic regression analysis showed lower average HU (Adj. OR 0.00 595% CI 0.0001-0.1713, p = 0.001) was an independent predictor of an ORC. The odds of an ORC increased by 1.7-fold for every 25 point decrease in average HU. CONCLUSIONS: The gold standard for assessing bone mineral density has been DXA t-scores, but the best predictor of ORC remains unclear. While both lower t-scores and average HU were associated with ORC, only HU was an independent predictor of ORC.

Methods Used to Generate Consensus Statements for Clinical Practice Guidelines: A Primer for the Spine Surgeon.

STUDY DESIGN: This was a research methodology study. OBJECTIVE: This review discusses the most commonly utilized consensus group methodologies for formulating clinical practice guidelines and current methods for accessing rigorous up-to-date clinical practice guidelines. SUMMARY OF BACKGROUND DATA: In recent years, clinical practice guidelines for the management of several conditions of the spine have emerged to provide clinicians with evidence-based best-practices. Many of these guidelines are used routinely by administrators, payers, and providers to determine the high-quality and cost-effective surgical practices. Most of these guidelines are formulated by consensus groups, which employ methodologies that are unfamiliar to most clinicians. METHODS: An extensive literature review was performed. The literature was then summarized in accordance with the authors' clinical experience. RESULTS: The Nominal Group Technique, Delphi method, and RAND-UCLA Appropriateness Model are 3 commonly utilized consensus group methodologies employed in the creation of clinical practice guidelines. Each of these methodologies has inherent advantages and disadvantages, is dependent on rigorously performed systematic reviews and meta-analyses to inform the panel of experts, and can be used to answer challenging clinical questions that remain unanswered due to a paucity of class I evidence. CONCLUSIONS: This review highlights the most commonly utilized consensus group methodologies and informs spine surgeons regarding options to access current clinical practice guidelines. LEVEL OF EVIDENCE: Level V.

Teriparatide Treatment Increases Hounsfield Units in the Thoracic Spine, Lumbar Spine, Sacrum, and Ilium Out of Proportion to the Cervical Spine.

STUDY DESIGN: This was a retrospective chart review. OBJECTIVE: The objective of this study was to compare the effect of teriparatide on Hounsfield Units (HU) in the cervical spine, thoracic spine, lumbar spine, sacrum, and pelvis. Second, to correlate HU changes at each spinal level with bone mineral density (BMD) on dual-energy x-ray absorptiometry (DXA). SUMMARY OF BACKGROUND DATA: HU represent a method to estimate BMD and can be used either separately or in conjunction with BMD from DXA. MATERIALS AND METHODS: A retrospective chart review included patients who had been treated with at least 6 months of teriparatide. HU were measured in the vertebral bodies of the cervical, thoracic, and lumbosacral spine and iliac crests. Lumbar and femoral neck BMD as measured on DXA was collected when available. RESULTS: One hundred twenty-five patients were identified for analysis with an average age of 67 years who underwent a mean (±SD) of 22±8 months of teriparatide therapy. HU improvement in the cervical spine was 11% (P=0.19), 25% in the thoracic spine (P=0.002), 23% in the lumbar spine (P=0.027), 17% in the sacrum (P=0.11), and 29% in the iliac crests (P=0.09). Lumbar HU correlated better than cervical HU with BMD as measured on DXA. CONCLUSIONS: Teriparatide increased average HU in the thoracolumbar spine to a proportionally greater extent than the cervical spine. The cervical spine had a higher baseline starting HU than the thoracolumbar spine. Lumbar HU correlated better than cervical and thoracic HU with BMD as measured on DXA.

C1 and C2 Fractures Above a Previous Fusion Treated with Internal Fixation without Fusion: A Case Report.

CASE: A 71-year-old woman sustained C1 lateral mass and type 2 odontoid fractures 3 years after C2-T2 anterior-posterior fusion. She was treated with C1-C4 instrumentation without fusion for 9 months followed by instrumentation removal to restore atlantoaxial motion. After instrumentation removal, she maintained clinically relevant cervical lateral bending, rotation, and flexion and extension. CONCLUSION: The loss of upper cervical motion after C1-C2 instrumented fusion may be debilitating for patients in the setting of previous subaxial cervical fusion. Temporary instrumentation without fusion may allow for preservation of upper cervical motion in patients with concomitant C1 and C2 fractures above a previous cervical fusion.

Surgical treatment of concomitant atlantoaxial instability and subaxial spondylotic stenosis in rheumatoid arthritis-a case report.

INTRODUCTION: This case report details the surgical treatment of an RA patient who presented with concomitant AAI and subaxial spondylotic stenosis and was subsequently treated via a C1-2 screw-rod construct, semispinalis cervicis sparing C3 laminectomy, and C4-C7 laminoplasty. Our case report is the first to describe a surgical approach for treatment of concomitant AAI and subaxial spondylotic stenosis in a patient with RA. CASE PRESENTATION: A 66-year-old male with a history of rheumatoid arthritis and atlantoaxial instability presented to an outpatient spine clinic with complaints of neck pain and worsening gait imbalance. A flexion-extension MRI revealed compression of the posterior aspect of the C1 ring on the back of the spinal cord during flexion, resulting in cord deformation; subaxial spondylosis with moderate associated stenosis and congenital narrowing from C3-7; and central cord compression with T2 signal change at C5-6. A C1-2 arthrodesis was performed and the subaxial spinal cord was then decompressed by performing a seminspinalis-sparing C3 laminectomy, C4-6 laminoplasties, and C7 dome laminectomy. Follow-up flexion-extension radiographs demonstrated satisfactory hardware position at C1-2 and full range of motion at C3-7. DISCUSSION: This is the first study to describe the surgical management of an RA patient with concomitant AAS and subaxial spondylotic stenosis. Patients with these simultaneous pathologies can be considered for decompression caudal to the C1-2 arthrodesis, though they should be adequately counseled regarding the risk of developing SAS requiring subsequent fusion.

Change in pelvic incidence between the supine and standing positions in patients with bilateral sacroiliac joint vacuum signs.

OBJECTIVE: Pelvic incidence (PI) is a commonly utilized spinopelvic parameter in the evaluation and treatment of patients with spinal deformity and is believed to be a fixed parameter. However, a fixed PI assumes that there is no motion across the sacroiliac (SI) joint, which has been disputed in recent literature. The objective of this study was to determine if patients with SI joint vacuum sign have a change in PI between the supine and standing positions. METHODS: A retrospective chart review identified patients with a standing radiograph, supine radiograph, and CT scan encompassing the SI joints within a 6-month period. Patients were grouped according to their SI joints having either no vacuum sign, unilateral vacuum sign, or bilateral vacuum sign. PI was measured by two independent reviewers. RESULTS: Seventy-three patients were identified with an average age of 66 years and a BMI of 30 kg/m2. Patients with bilateral SI joint vacuum sign (n = 27) had an average absolute change in PI of 7.2° (p < 0.0001) between the standing and supine positions compared to patients with unilateral SI joint vacuum sign (n = 20) who had a change of 5.2° (p = 0.0008), and patients without an SI joint vacuum sign (n = 26) who experienced a change of 4.1° (p = 0.74). ANOVA with post hoc Tukey test showed a statistically significant difference in the change in PI between patients with the bilateral SI joint vacuum sign and those without an SI joint vacuum sign (p = 0.023). The intraclass correlation coefficient between the two reviewers was 0.97 for standing PI and 0.96 for supine PI (p < 0.0001). CONCLUSIONS: Patients with bilateral SI joint vacuum signs had a change in PI between the standing and supine positions, suggesting there may be increasing motion across the SI joint with significant joint degeneration.

Nonsurgical Management of Combined Occipitocervical and Atlantoaxial Distraction Injuries: A Case Report.

CASE: A 41-year-old man sustained occipitocervical dislocation (OCD) and atlantoaxial dislocation (AAD) injuries in a motor vehicle collision. These injuries were treated nonoperatively with a hard cervical collar and activity restrictions with an excellent result at 4-year follow-up. CONCLUSION: OCD and AAD injuries require prompt diagnosis and immobilization. Standard of care for coexisting injuries is occipitocervical fusion; however, some patients have coexisting injuries which may prevent operative treatment. These polytrauma patients require a creative nonoperative approach with close follow-up to avoid neurologic decline.

Anterior Cervical Osteophyte Resection for Treatment of Dysphagia.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVES: When anterior cervical osteophytes become large enough, they may cause dysphagia. There is a paucity of work examining outcomes and complications of anterior cervical osteophyte resection for dysphagia. METHODS: Retrospective review identified 19 patients who underwent anterior cervical osteophyte resection for a diagnosis of dysphagia. The mean age was 71 years and follow-up, 4.7 years. The most common level operated on was C3-C4 (13, 69%). RESULTS: Following anterior cervical osteophyte resection, 79% of patients had improvement in dysphagia. Five patients underwent cervical fusion; there were no episodes of delayed or iatrogenic instability requiring fusion. Fusion patients were younger (64 vs 71 years, P = .05) and had longer operative times (315 vs 121 minutes, P = .01). Age of 75 years or less trended toward improvement in dysphagia (P = .09; OR = 18.8; 95% CI 0.7-478.0), whereas severe dysphagia trended toward increased complications (P = .07; OR = 11.3; 95% CI = 0.8-158.5). Body mass index, use of an exposure surgeon, diffuse idiopathic skeletal hyperostosis diagnosis, surgery at 3 or more levels, prior neck surgery, and fusion were not predictive of improvement or complication. CONCLUSIONS: Anterior cervical osteophyte resection improves swallowing function in the majority of patients with symptomatic osteophytes. Spinal fusion can be added to address stenosis and other underlying cervical disease and help prevent osteophyte recurrence, whereas intraoperative navigation can be used to ensure complete osteophyte resection without breaching the cortex or entering the disc space. Because of the relatively high complication rate, patients should undergo thorough multidisciplinary workup with swallow evaluation to confirm that anterior cervical osteophytes are the primary cause of dysphagia prior to surgery.

Regional improvements in lumbosacropelvic Hounsfield units following teriparatide treatment.

OBJECTIVE: Opportunistic Hounsfield unit (HU) determination from CT imaging has been increasingly used to estimate bone mineral density (BMD) in conjunction with assessments from dual energy x-ray absorptiometry (DXA). The authors sought to compare the effect of teriparatide on HUs across different regions in the pelvis, sacrum, and lumbar spine, as a surrogate measure for the effects of teriparatide on lumbosacropelvic instrumentation. METHODS: A single-institution retrospective review of patients who had been treated with at least 6 months of teriparatide was performed. All patients had at least baseline DXA as well as pre- and post-teriparatide CT imaging. HUs were measured in the pedicle, lamina, and vertebral body of the lumbar spine, in the sciatic notch, and at the S1 and S2 levels at three different points (ilium, sacral body, and sacral ala). RESULTS: Forty patients with an average age of 67 years underwent a mean of 20 months of teriparatide therapy. Mean HUs of the lumbar lamina, pedicles, and vertebral body were significantly different from each other before teriparatide treatment: 343 ± 114, 219 ± 89.2, and 111 ± 48.1, respectively (p < 0.001). Mean HUs at the S1 level for the ilium, sacral ala, and sacral body were also significantly different from each other: 124 ± 90.1, -10.7 ± 61.9, and 99.1 ± 72.1, respectively (p < 0.001). The mean HUs at the S2 level for the ilium and sacral body were not significantly different from each other, although the mean HU at the sacral ala (-11.9 ± 52.6) was significantly lower than those at the ilium and sacral body (p = 0.003 and 0.006, respectively). HU improvement occurred in most regions following teriparatide treatment. In the lumbar spine, the mean lamina HU increased from 343 to 400 (p < 0.001), the mean pedicle HU increased from 219 to 242 (p = 0.04), and the mean vertebral body HU increased from 111 to 134 (p < 0.001). There were also significant increases in the S1 sacral body (99.1 to 130, p < 0.05), S1 ilium (124 vs 165, p = 0.01), S1 sacral ala (-10.7 vs 3.68, p = 0.04), and S2 sacral body (168 vs 189, p < 0.05). CONCLUSIONS: There was significant regional variation in lumbar and sacropelvic HUs, with most regions significantly increasing following teriparatide treatment. The sacropelvic area had lower HU values than the lumbar spine, more regional variation, and a higher degree of correlation with BMD as measured on DXA. While teriparatide treatment resulted in HUs > 110 in the majority of the lumbosacral spine, the HUs in the sacral ala remained suggestive of severe osteoporosis, which may limit the effectiveness of fixation in this region.

Osteoporosis in spine surgery patients: what is the best way to diagnose osteoporosis in this population?

OBJECTIVE: The goal of this study was to compare different recognized definitions of osteoporosis in patients with degenerative lumbar spine pathology undergoing elective spinal fusion surgery to determine which patient population should be considered for preoperative optimization. METHODS: A retrospective review of patients in whom lumbar spine surgery was planned at 2 academic medical centers was performed, and the rate of osteoporosis was compared based on different recognized definitions. Assessments were made based on dual-energy x-ray absorptiometry (DXA), CT Hounsfield units (HU), trabecular bone score (TBS), and fracture risk assessment tool (FRAX). The rate of osteoporosis was compared based on different definitions: 1) the WHO definition (T-score ≤ -2.5) at total hip or spine; 2) CT HU of < 110; 3) National Bone Health Alliance (NBHA) guidelines; and 4) "expanded spine" criteria, which includes patients meeting NBHA criteria and/or HU < 110, and/or "degraded" TBS in the setting of an osteopenic T-score. Inclusion criteria were adult patients with a DXA scan of the total hip and/or spine performed within 1 year and a lumbar spine CT scan within 6 months of the physician visit. RESULTS: Two hundred forty-four patients were included. The mean age was 68.3 years, with 70.5% female, 96.7% Caucasian, and the mean BMI was 28.8. Fracture history was reported in 53.8% of patients. The proportion of patients identified with osteoporosis on DXA, HUs, NBHA guidelines, and the authors' proposed "expanded spine" criteria was 25.4%, 36.5%, 75%, and 81.9%, respectively. Of the patients not identified with osteoporosis on DXA, 31.3% had osteoporosis based on HU, 55.1% had osteoporosis with NBHA, and 70.4% had osteoporosis with expanded spine criteria (p < 0.05), with poor correlations among the different assessment tools. CONCLUSIONS: Limitations in the use of DXA T-scores alone to diagnose osteoporosis in patients with lumbar spondylosis has prompted interest in additional methods of evaluating bone health in the spine, such as CT HU, TBS, and FRAX, to inform guidelines that aim to reduce fracture risk. However, no current osteoporosis assessment was developed with a focus on improving outcomes in spinal surgery. Therefore, the authors propose an expanded spine definition for osteoporosis to identify a more comprehensive cohort of patients with potential poor bone health who could be considered for preoperative optimization, although further study is needed to validate these results in terms of clinical outcomes.

Computer-assisted navigation in complex cervical spine surgery: tips and tricks.

Stereotactic navigation is quickly establishing itself as the gold standard for accurate placement of spinal instrumentation and providing real-time anatomic referencing. There have been substantial improvements in computer-aided navigation over the last decade producing improved accuracy with intraoperative scanning while shortening registration time. The newest iterations of modeling software create robust maps of the anatomy while tracking software localizes instruments in multiple display modes. As a result, stereotactic navigation has become an effective adjunct to spine surgery, particularly improving instrumentation accuracy in the setting of atypical anatomy. This article provides an overview of stereotactic navigation applied to complex cervical spine surgery, details the means for registration and direct referencing, and shares our preferred methods to implement this promising technology.