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Kevin C. Yao and Adel M. Malek

Object

The resection of spinal hemangiomas is often challenging because of characteristic high-volume and potentially prohibitive intraoperative blood loss. Although transarterial embolization can mitigate this risk, it can be suboptimal when tumor arterial supply is diffuse or poorly defined. The authors present their experience in the use of preoperative percutaneous direct injection of spinal hemangiomas with N-butyl cyanoacrylate (NBCA) as an effective preoperative adjunct that may reduce operative blood loss and facilitate resection of these vascular tumors.

Methods

Four patients with symptomatic spinal hemangiomas were treated using percutaneous transpedicular direct NBCA-Lipiodol injection; 2 patients had undergone prior spinal angiography, with suboptimal transarterial embolization in 1. Each patient underwent percutaneous bilateral transpedicular NBCA-assisted tumor embolization prior to resection. Retrospective analysis of operative times, blood loss, and clinical data is presented.

Results

There were no complications associated with the percutaneous NBCA embolization technique. The procedure was effective at facilitating tumor removal and minimizing intraoperative blood loss, especially at the vertebral body resection stage. Improved tumor filling was achieved as the filling characteristics of dilute NBCA-Lipiodol mixture within large-channel, high-flow hemangiomas were appreciated with experience.

Conclusions

Transpedicular NBCA direct-puncture embolization of spinal hemangiomas is an effective preoperative adjunct that facilitates resection of these highly vascular tumors. It is particularly useful when transarterial embolization is unsafe or suboptimal due to constraints imposed by the local angioarchitecture.

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Kevin C. Yao, Stefano Boriani, Ziya L. Gokaslan and Narayan Sundaresan

Object

Spinal metastases are prevalent in the population of patients with cancer. Effective cancer therapy must incorporate treatment strategies for these lesions. Increasingly, surgery is being recognized as an effective treatment modality both for the patient's quality of life and potential oncological cure. En bloc spondylectomy is the surgical procedure of choice to obtain these goals. The purpose of this study was to examine critically the rationale, indications, and outcomes of en bloc spondylectomy for spinal metastases.

Methods

Outcomes in the authors' series of patients who underwent en bloc spondylectomy for spinal metastases are critically analyzed. The rationale and indications for this procedure are discussed. The Weinstein, Boriani, and Biagini surgical staging system for spinal tumors is described. A review of the literature is performed to examine further the rationale underlying this aggressive surgical approach to metastatic spinal disease.

Conclusions

En bloc spondylectomy is the treatment of choice for solitary and oligometastatic spinal metastases with biologically favorable histological findings. In appropriately selected patients, neurological outcome, pain control, and oncological control are significantly better after en bloc spondylectomy compared with radiation therapy. Oncological outcomes also exceed those of intralesional techniques. The Weinstein, Boriani, and Biagini surgical staging system provides a standard with which to plan surgical approaches and to compare surgical outcomes.

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Peter D. Angevine and Paul C. McCormick

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William R. Miele, Clemens M. Schirmer, Kevin C. Yao and Carl B. Heilman

The pathogenesis of Chiari malformation Type I (CM-I) and associated syringomyelia is incompletely understood. Patients often present in middle age with incidental or minimally symptomatic CM-I, whose management is controversial. One option is clinical and radiographic observation of asymptomatic and minimally symptomatic patients. The authors here present the case of a 36-year-old woman who had been monitored for 6 years for a minimally symptomatic CM-I and cervicothoracic syrinx. After 5 years of follow-up, she suffered spontaneous rupture of a cerebral cavernous malformation when she was 27 weeks pregnant. The ruptured cavernous malformation and hematoma were operatively managed via a right frontal craniotomy. Ten months after the craniotomy for resection of the ruptured cavernous malformation, follow-up MRI demonstrated resolution of the CM-I and syrinx. Few similar cases have been reported in adults. This case argues for the presence of dynamic factors in the development and maintenance of CM-I and supports the nonoperative treatment of asymptomatic and minimally symptomatic patients.

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Kevin C. Yao, Tadashi Komata, Yasuko Kondo, Takao Kanzawa, Seiji Kondo and Isabelle M. Germano

Object. Ionizing radiation is the gold-standard adjuvant treatment for glioblastoma multiforme (GBM), the most aggressive primary brain tumor. The mechanisms underlying neoplastic glial cell growth inhibition after administration of ionizing radiation, however, remain largely unknown. In this report, the authors characterize the response of GBM cells to ionizing radiation and elucidate factors that correlate with the radiosensitivity of these tumors.

Methods. Six human GBM cell lines were subjected to increasing doses of radiation. Each demonstrated a dose-dependent suppression of cell proliferation. In the most radiosensitive cell line, the authors demonstrated a transient increase in the expression of the cyclin-dependent kinase inhibitors (CDKIs) p21 and p27, which corresponded with a G1 cell-cycle arrest. In contrast, the most radioresistant cell line demonstrated a decrease in p21 and p27 expression levels, which correlated with a failure to arrest. Apoptosis did not occur in any cell line following irradiation. Instead, autophagic cell changes were observed following administration of radiation, regardless of the relative radiosensitivity of the cell line.

Conclusions. These findings elucidate some of the molecular responses of GBMs to irradiation and suggest novel targets for future therapy.

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Tomas Dvorak, Arkadiy Finn, Lori Lyn Price, John E. Mignano, Markus M. Fitzek, Julian K. Wu and Kevin C. Yao

Object

Trigeminal neuralgia (TN) is a disorder of the trigeminal nerve that results in intense episodic pain. Primary treatment with Gamma Knife surgery (GKS) is well established; however, a significant number of patients experience recurrence of TN over time. Repeat GKS can be performed, but the retreatment dose has not been well established. In this study, the authors present their institutional retreatment results and compare them with other series.

Methods

Between December 2003 and January 2006, 28 patients were treated at Tufts Medical Center with repeat GKS for recurrence of TN. All patients had been initially treated with GKS at this institution, and only those with significant pain improvement were offered retreatment. The maximum dose was prescribed using a single isocenter; the 4-mm collimator was used. The initial median GKS dose was 80 Gy, the median retreatment dose was 45 Gy, and the median cumulative dose was 125 Gy. The median time between GKS procedures was 18.1 months. Facial pain outcomes were defined using the Marseille scale. Excellent outcome was defined as no pain (with or without medications), and good outcome was defined as > 50% pain relief. Toxicity was categorized as none, mild, or bothersome. The median clinical follow-up after the second GKS was 19.7 months. Our clinical outcomes were compared with 8 previously reported retreatment series (including 1 abstract), both for rate of pain control and for rate of complications.

Results

Outcomes after the second GKS were excellent in 29% (8 patients), good in 32% (9), and poor in 39% (11). Four patients (14%) experienced no improvement after repeat GKS. Eight patients (29%) experienced new trigeminal nerve dysfunction, including numbness (11%), paresthesia (14%), dysesthesia (4%), taste alteration (11%), and bite weakness (4%). None of these were bothersome. No patient developed corneal numbness. Univariate analysis failed to reveal any significant predictors of pain control or complications.

Seven published peer-reviewed retreatment series and the authors' data (total 215 patients) were analyzed. There was a cumulative dose-response relationship for both pain control (p = 0.04) and new trigeminal dysfunction (p = 0.08). Successful pain control was strongly correlated with development of new dysfunction (p = 0.02). A cumulative dose > 130 Gy was more likely to result in successful (> 50%) pain control, but was also more likely (> 20%) to result in development of new dysfunction.

Conclusions

Successful retreatment of patients in whom the initial GKS treatment fails is feasible. Patients who respond initially may be at a higher risk of retreatment-related complications. There appears to be a dose-response relationship for both pain control and development of new side effects. It is important to counsel and treat patients individually based on this dose-response relationship.

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Kevin C. Yao, Matthew J. McGirt, Kaisorn L. Chaichana, Shlomi Constantini and George I. Jallo

Object

Gross-total resection of pediatric intramedullary spinal cord tumors (IMSCTs) can be achieved in the majority of cases, with preservation of long-term neurological function. However, progressive spinal deformity requiring subsequent fusion occurs in many cases. It remains unknown which subgroups of patients have the greatest risk for progressive spinal deformity.

Methods

Data for 161 patients undergoing resection of IMSCTs at a single institution were retrospectively collected and analyzed with regard to the development of progressive spinal deformity requiring fusion and patient functional status (based on the modified McCormick Scale [mMS] and Karnofsky Performance Scale [KPS]) by conducting telephone interviews corroborated by medical records. The independent association of all clinical, radiographic, and operative variables to subsequent progressive spinal deformity was assessed using multivariate logistic regression analysis.

Results

Patients were a mean of 8.6 ± 5.7 years old at the time of surgery. The tumor spanned a mean of six ± three spinal levels. Preoperative scoliotic deformity was present in 56 cases (35%). Seventy-six patients (47%) had undergone a previous biopsy procedure, and 28 (17%) a prior resection. Gross-total resection (> 95%) was achieved in 122 cases (76%). A median of 9 years (range 1–21) after surgery, progressive spinal deformity requiring fusion developed in 43 patients (27%). The median functional scores at the last follow-up were worse in patients who required fusion compared with those who did not (mMS: 3 compared with 2, p = 0.006; KPS: 80 compared with 90, p = 0.04) despite similar mMS scores between the groups at 3 months postoperatively. An age less than 13 years, preoperative scoliotic deformity (Cobb angle > 10°), involvement of the thoracolumbar junction, and tumor-associated syrinx independently increased the odds of a postoperative progressive deformity requiring fusion 4.4-, 3.2-, 2.6-, and 3.4-fold, respectively (p < 0.05). Each subsequent resection increased the odds of a progressive deformity 1.8-fold (p < 0.05). Symptoms lasting less than 1 month before resection decreased the odds of spinal deformity requiring fusion ninefold (p < 0.05).

Conclusions

Progressive spinal deformity requiring fusion occurred in 27% of children undergoing resection of an IMSCT and was associated with a decreased functional status. Preoperative scoliotic deformity, an increasing number of resections, an age less than 13 years, tumor-associated syrinx, and surgery spanning the thoracolumbar junction increased the risk for progressive spinal deformity. Patients possessing one or more of these characteristics should be monitored closely for progressive spinal deformity following surgery.

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Matthew J. McGirt, Kaisorn L. Chaichana, April Atiba, Ali Bydon, Timothy F. Witham, Kevin C. Yao and George I. Jallo

Object

Gross-total resection of pediatric intramedullary spinal cord tumor (IMSCT) can be achieved in the majority of cases while preserving long-term neurological function. Nevertheless, postoperative progressive spinal deformity often complicates functional outcome years after surgery. The authors set out to determine whether laminoplasty in comparison with laminectomy has reduced the incidence of subsequent spinal deformity requiring fusion after IMSCT resection at their institution.

Methods

The first 144 consecutive patients undergoing resection of IMSCTs at a single institution underwent laminectomy with preservation of facet joints. The next 20 consecutive patients presenting for resection of IMSCTs underwent osteoplastic laminotomy regardless of patient or tumor characteristics. All patients were followed up with telephone interviews corroborated by medical records for the following outcomes: 1) neurological and functional status (modified McCormick Scale [MMS] score and Karnofsky Performance Scale [KPS] score); and 2) development of progressive spinal deformity requiring fusion. The incidence of progressive spinal deformity and the long-term neurological function were compared between the laminectomy and osteoplastic laminotomy cohorts. The means are expressed ± the standard deviation.

Results

Overall, the patients' mean age was 8.6 ± 5 years, and they presented with median MMS scores of 2 (interquartile range [IQR] 2–4). A > 95% resection was achieved in 125 cases (76%). There were no differences (p > 0.10) between patients treated with osteoplastic laminotomy and those treated with laminectomy in terms of the following characteristics: age; sex; duration of symptoms; location of tumor; incidence of preoperative scoliosis (Cobb angle > 10°: 7 [35%] with laminoplasty compared with 49 [34%] with laminectomy); involvement of the cervicothoracic junction (7 [35%] compared with 57 [40%]); thoracolumbar junction (4 [20%] compared with 36 [25%]); tumor size; extent of resection; radiation therapy; histopathological findings; or mean operative spinal levels (7.5 ± 2 compared with 7.5 ± 3). Nevertheless, patients who underwent osteoplastic laminotomy had better median preoperative MMS scores than those treated with laminectomy (2 [IQR 2–2] compared with 2 [IQR 2–4]; p = 0.04). A median of 3.5 years (IQR 1–7 years) after surgery, only 1 patient (5%) in the osteoplastic laminotomy cohort required fusion for progressive spinal deformity, compared with 43 (30%) in the laminectomy cohort (p = 0.027). Adjusting for the inter-cohort difference in preoperative MMS scores, osteoplastic laminotomy was associated with a 7-fold reduction in the odds of subsequent fusion for progressive spinal deformity (odds ratio 0.13, 95% confidence interval 0.02–1.00; p = 0.05). The median MMS and KPS scores were similar between patients who underwent osteoplastic laminotomy and those in whom laminectomy was performed (MMS Score 2 [IQR 2–3] for laminotomy compared with 2 [IQR 2–4] for laminectomy, p = 0.54; KPS Score 90 [IQR 70–100] for laminotomy compared with 90 [IQR 80–90] for laminectomy, p = 0.545) at a median of 3.5 years after surgery.

Conclusions

In the authors' experience, osteoplastic laminotomy for the resection of IMSCT in children was associated with a decreased incidence of progressive spinal deformity requiring fusion but did not affect long-term functional outcome. Laminoplasty used for pediatric IMSCT resection may decrease the incidence of progressive spinal deformity requiring subsequent spinal stabilization in some patients.

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Matthew J. McGirt, Kaisorn L. Chaichana, April Atiba, Frank Attenello, Kevin C. Yao and George I. Jallo

Object

With modern surgical advances, radical resection of pediatric intramedullary spinal cord tumors (IMSCTs) can be expected to preserve long-term neurological function. Nevertheless, postoperative neurological decline is not uncommon after surgery, and many patients continue to experience long-term dysesthetic symptoms. Preoperative predictors of postoperative neurological decline and sensory syndromes have not been investigated and may serve as a guide for surgical risk stratification.

Methods

Neurological function (as determined using the modified McCormick Scale [mMS]) preoperatively, postoperatively, and 3 months after surgery was retrospectively recorded from patient charts in 164 consecutive patients undergoing resection of IMSCTs. A median 4 years (interquartile range [IQR] 1–8 years) after surgery, long-term motor and sensory symptoms were assessed by telephone interviews and corroborated by subsequent medical visits in 120 available patients. This long-term assessment was retrospectively reviewed for the purposes of this study. The authors reviewed this series to assess long-term motor, sensory, and urinary outcomes and to determine independent risk factors of postoperative neurological decline and long-term sensory dysfunction.

Results

Patients were 8.6 ± 5.7 years old and presented with a median mMS of 2 (IQR 2–4). Three months after surgery, 38 patients (23%) continued to experience decreased neurological function (1 mMS point) incurred perioperatively. Increasing age (p = 0.028), unilateral symptoms (p = 0.046), and urinary dysfunction at presentation (p = 0.004) independently predicted persistent 3-month perioperative decline. At long-term follow-up (median 4 years), 39 (33%) exhibited improvements in their mMS scores, 13 (30%) had improvement in their urinary dysfunction, and 27 (30%) had resolution of their dysesthesias. Seventy-eight patients (65%) experienced long-term dysesthetic symptoms. Increasing age (p = 0.024), preoperative symptom duration > 12 months (p = 0.027), and worsened postoperative mMS score at hospital discharge (p = 0.013) independently increased the risk of long-term dysesthesias.

Conclusions

In the authors' experience, nearly one third of patients may experience improvement in motor, sensory, and urinary dysfunction years after IMSCT resection, whereas the majority will continue to experience long-term dysesthetic symptoms. Improvement in motor deficits preceded improvement in sensory syndromes, and urinary dysfunction typically resolved much longer after surgery. The risk of persistent perioperative motor decline was increased with older age, unilateral symptoms, preoperative urinary symptoms, and less severe preoperative neurological deficit. The risk of long-term dysesthesias was increased with older age, increased duration of symptoms prior to resection, and greater postoperative neurological deficit.

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Jonathan J. Rasouli, Brooke T. Kennamer, Frank M. Moore, Alfred Steinberger, Kevin C. Yao, Omar N. Syed, Marc S. Arginteanu and Yakov Gologorsky

OBJECTIVE

The C7 vertebral body is morphometrically unique; it represents the transition from the subaxial cervical spine to the upper thoracic spine. It has larger pedicles but relatively small lateral masses compared to other levels of the subaxial cervical spine. Although the biomechanical properties of C7 pedicle screws are superior to those of lateral mass screws, they are rarely placed due to increased risk of neurological injury. Although pedicle screw stimulation has been shown to be safe and effective in determining satisfactory screw placement in the thoracolumbar spine, there are few studies determining its utility in the cervical spine. Thus, the purpose of this study was to determine the feasibility, clinical reliability, and threshold characteristics of intraoperative evoked electromyographic (EMG) stimulation in determining satisfactory pedicle screw placement at C7.

METHODS

The authors retrospectively reviewed a prospectively collected data set. All adult patients who underwent posterior cervical decompression and fusion with placement of C7 pedicle screws at the authors’ institution between January 2015 and March 2019 were identified. Demographic, clinical, neurophysiological, operative, and radiographic data were gathered. All patients underwent postoperative CT scanning, and the position of C7 pedicle screws was compared to intraoperative neurophysiological data.

RESULTS

Fifty-one consecutive C7 pedicle screws were stimulated and recorded intraoperatively in 25 consecutive patients. Based on EMG findings, 1 patient underwent intraoperative repositioning of a C7 pedicle screw, and 1 underwent removal of a C7 pedicle screw. CT scans demonstrated ideal placement of the C7 pedicle screw in 40 of 43 instances in which EMG stimulation thresholds were > 15 mA. In the remaining 3 cases the trajectories were suboptimal but safe. When the screw stimulation thresholds were between 11 and 15 mA, 5 of 6 screws were suboptimal but safe, and in 1 instance was potentially dangerous. In instances in which the screw stimulated at thresholds ≤ 10 mA, all trajectories were potentially dangerous with neural compression.

CONCLUSIONS

Ideal C7 pedicle screw position strongly correlated with EMG stimulation thresholds > 15 mA. In instances, in which the screw stimulates at values between 11 and 15 mA, screw trajectory exploration is recommended. Screws with thresholds ≤ 10 mA should always be explored, and possibly repositioned or removed. In conjunction with other techniques, EMG threshold testing is a useful and safe modality in determining appropriate C7 pedicle screw placement.