Risk assessment of early therapeutic anticoagulation following cranial surgery: an institutional case series

OBJECTIVE

Postoperative thrombotic complications represent a unique challenge in cranial neurosurgery as primary treatment involves therapeutic anticoagulation. The decision to initiate therapy and its timing is nuanced, as surgeons must balance the risk of catastrophic intracranial hemorrhage (ICH). With limited existing evidence to guide management, current practice patterns are subjective and inconsistent. The authors assessed their experience with early therapeutic anticoagulation (≤ 7 days postoperatively) initiation for thrombotic complications in neurosurgical patients undergoing cranial surgery to better understand the risks of catastrophic ICH.

METHODS

Adult patients treated with early therapeutic anticoagulation following cranial surgery were considered. Anticoagulation indications were restricted to thrombotic or thromboembolic complications. Records were retrospectively reviewed for demographics, surgical details, and anticoagulation therapy start. The primary outcome was the incidence of catastrophic ICH, defined as ICH resulting in reoperation or death within 30 days of anticoagulation initiation. As a secondary outcome, post-anticoagulation cranial imaging was reviewed for new or worsening acute blood products. Fisher's exact and Wilcoxon rank-sum tests were used to compare cohorts. Cumulative outcome analyses were performed for primary and secondary outcomes according to anticoagulation start time.

RESULTS

Seventy-one patients satisfied the inclusion criteria. Anticoagulation commenced on mean postoperative day (POD) 4.3 (SD 2.2). Catastrophic ICH was observed in 7 patients (9.9%) and was associated with earlier anticoagulation initiation (p = 0.02). Of patients with catastrophic ICH, 6 (85.7%) had intra-axial exploration during their index surgery. Patients with intra-axial exploration were more likely to experience a catastrophic ICH postoperatively compared to those with extra-axial exploration alone (OR 8.5, p = 0.04). Of the 58 patients with postoperative imaging, 15 (25.9%) experienced new or worsening blood products. Catastrophic ICH was 9 times more likely with anticoagulation initiation within 48 hours of surgery (OR 8.9, p = 0.01). The cumulative catastrophic ICH risk decreased with delay in initiation of anticoagulation, from 21.1% on POD 2 to 9.9% on POD 7. Concurrent antiplatelet medication was not associated with either outcome measure.

CONCLUSIONS

The incidence of catastrophic ICH was significantly increased when anticoagulation was initiated within 48 hours of cranial surgery. Patients undergoing intra-axial exploration during their index surgery were at higher risk of a catastrophic ICH.

Transcervical, retropharyngeal odontoidectomy - Anatomical considerations

Context

Anterior craniocervical junction lesions have always been a challenge for neurosurgeons. Presenting with lower cranial nerve dysfunction and symptoms of brainstem compression, decompression is often required. While posterior approaches offer indirect ventral brainstem decompression, direct decompression via odontoidectomy is necessary when they fail. The transoral and endoscopic endonasal approaches have been explored but come with their own limitations and risks. A novel retropharyngeal approach to the cervical spine has shown promising results with reduced complications.

Aims

This study aims to explore the feasibility and potential advantages of the anterior retropharyngeal approach for accessing the odontoid process.

Methods and Surgical Technique

To investigate the anatomical aspects of the anterior retropharyngeal approach, a paramedian skin incision was performed below the submandibular gland on two cadaveric specimens. The subcutaneous tissue followed by the platysma is dissected, and the superficial fascial layer is opened. The plane between the vascular sheath laterally and the pharyngeal structures medially is entered below the branching point of the facial vein and internal jugular vein. After reaching the prevertebral plane, further dissection cranially is done in a blunt fashion below the superior pharyngeal nerve and artery. Various anatomical aspects were highlighted during this approach.

Results

The anterior, submandibular retropharyngeal approach to the cervical spine was performed successfully on two cadavers highlighting relevant anatomical structures, including the carotid artery and the glossopharyngeal, hypoglossal, and vagus nerves. This approach offered wide exposure, avoidance of oropharyngeal contamination, and potential benefit in repairing cerebrospinal fluid fistulas.

Conclusions

For accessing the craniocervical junction, the anterior retropharyngeal approach is a viable technique that offers many advantages. However, when employing this approach, surgeons must have adequate anatomical knowledge and technical proficiency to ensure better outcomes. Further studies are needed to enhance our anatomical variations understanding and reduce intraoperative risks.

Metastatic Breast Cancer to the Spine: Incidence of Somatic Gene Alterations and Association of Targeted Therapies With Overall Survival

BACKGROUND

The increase in use of targeted systemic therapies in cancer treatments has catalyzed the importance of identifying patient- and tumor-specific somatic mutations, especially regarding metastatic disease. Mutations found to be most prevalent in patients with metastatic breast cancer include TP53, PI3K, and CDH1.

OBJECTIVE

To determine the incidence of somatic mutations in patients with metastatic breast cancer to the spine (MBCS). To determine if a difference exists in overall survival (OS), progression-free survival, and progression of motor symptoms between patients who do or do not undergo targeted systemic therapy after treatment for MBCS.

METHODS

This is a retrospective study of patients with MBCS. Review of gene sequencing reports was conducted to calculate the prevalence of various somatic gene mutations within this population. Those patients who then underwent treatment (surgery/radiation) for their diagnosis of MBCS between 2010 and 2020 were subcategorized. The use of targeted systemic therapy in the post-treatment period was identified, and post-treatment OS, progression-free survival, and progression of motor deficits were calculated for this subpopulation.

RESULTS

A total of 131 patients were included in the final analysis with 56% of patients found to have a PI3K mutation. Patients who received targeted systemic therapies were found to have a significantly longer OS compared with those who did not receive targeted systemic therapies.

CONCLUSION

The results of this study demonstrate that there is an increased prevalence of PI3K mutations in patients with MBCS and there are a significant survival benefit and delay in progression of motor symptoms associated with using targeted systemic therapies for adjuvant treatment.

Characterizing the Next Generation of Neurosurgeons: A Descriptive Analysis and Publicly Available Web Application of Neurosurgery Residency Programs' Website Data

OBJECTIVE

Neurosurgery program websites serve as a valuable resource for applicants. However, each website exists in isolation, and it can be difficult to understand the general trends in U.S. neurosurgery resident demographics. In the present study, we collected data from program websites and analyzed the trends in the demographics of the current U.S. neurosurgery residents.

METHODS

We used a program list obtained from the American Association of Medical Colleges Electronic Residency Application System to extract data from the current resident complement listed in each program's website, including program, year in program, medical school, sex (male vs. female), graduate and/or PhD degrees, and assessed the trends during 7 years of resident data using linear regression.

RESULTS

We identified 116 neurosurgery residency programs in the United States, with 111 providing information on their current resident complement, yielding a dataset of 1599 residents. Of these 1599 residents, 348 (22%) were female, 301 (19%) had a graduate degree in addition to an MD or DO degree, 151 (9.4%) had a PhD degree, 300 (19%) had matched at the program affiliated with their medical school, and 121 (7.6%) had graduated from a foreign medical school. The proportion of matriculating female residents had increased an average of 2.1% annually (95% confidence interval, 0.6%-3.7%) from 2015 to 2021. The other demographic data had not changed significantly during the same period.

CONCLUSIONS

In addition to summarizing the current resident demographics, our analysis identified a significant increase in the proportion of female residents between 2015 (15.1%) and 2021 (25.6%). This publicly available dataset should enable additional analyses of the evolution of neurosurgery resident demographics.

Attitudes and trends in the use of radiolucent spinal implants: A survey of the North American Spine Society section of spinal oncology

Background

In spinal oncology, titanium implants pose several challenges including artifact on advanced imaging and therapeutic radiation perturbation. To mitigate these effects, there has been increased interest in radiolucent carbon fiber (CF) and CF-reinforced polyetheretherketone (CFR-PEEK) implants as an alternative for spinal reconstruction. This study surveyed the members of the North American Spine Society (NASS) section of Spinal Oncology to query their perspectives regarding the clinical utility, current practice patterns, and recommended future directions of radiolucent spinal implants.

Methods

In February 2021, an anonymous survey was administered to the physicians of the NASS section of Spinal Oncology. Participation in the survey was optional. The survey contained 38 items including demographic questions as well as multiple-choice, yes/no questions, Likert rating scales, and short free-text responses pertaining to the “clinical concept”, “efficacy”, “problems/complications”, “practice pattern”, and “future directions” of radiolucent spinal implants.

Results

Fifteen responses were received (71.4% response rate). Six of the participants (40%) were neurosurgeons, eight (53.3%) were orthopedic surgeons, and one was a spinal radiation oncologist. Overall, there were mixed opinions among the specialists. While several believed that radiolucent spinal implants provide substantial benefits for the detection of disease recurrence and radiation therapy options, others remained less convinced. Ongoing concerns included high costs, low availability, limited cervical and percutaneous options, and suboptimal screw and rod designs. As such, participants estimated that they currently utilize these implants for 27.3% of anterior and 14.7% of all posterior reconstructions after tumor resection.

Conclusion

A survey of the NASS section of Spinal Oncology found a lack of consensus with regards to the imaging and radiation benefits, and several ongoing concerns about currently available options. Therefore, routine utilization of these implants for anterior and posterior spinal reconstructions remains low. Future investigations are warranted to practically validate these devices’ theoretical risks and benefits.

Reducing Wrong-level Spinal Surgeries Through Root Cause Analyses: A 10-year Longitudinal Analysis of a Single Tertiary Institution's Iterative Policy Improvements

MINI

This study is a comprehensive narrative of all wrong-level spine surgeries and prevention strategies employed at our institution between 2008 and 2019, and aims to provide a roadmap for developing a rigorous prevention protocol. We systematically track root cause analyses and policy changes to determine which prevention strategies are most effective.

Factors associated with adjacent-level tumor progression in patients receiving surgery followed by radiosurgery for metastatic epidural spinal cord compression

OBJECTIVE

Separation surgery followed by spine stereotactic radiosurgery (SSRS) has been shown to achieve favorable rates of local tumor control and patient-reported outcomes in patients with metastatic epidural spinal cord compression (MESCC). However, rates and factors associated with adjacent-level tumor progression (ALTP) in this population have not yet been characterized. The present study aimed to identify factors associated with ALTP and examine its association with overall survival (OS) in patients receiving surgery followed by radiosurgery for MESCC.

METHODS

Thirty-nine patients who underwent separation surgery followed by SSRS for MESCC were identified using a prospectively collected database and were retrospectively reviewed. Radiological measurements were collected from preoperative, postoperative, and post-SSRS MRI. Statistical analysis was conducted using the Kaplan-Meier product-limit method and Cox proportional hazards test. Subgroup analysis was conducted for patients who experienced ALTP into the epidural space (ALTP-E).

RESULTS

The authors' cohort included 39 patients with a median OS of 14.7 months (range 2.07-96.3 months). ALTP was observed in 16 patients (41.0%) at a mean of 6.1 ± 5.4 months postradiosurgery, of whom 4 patients (10.3%) experienced ALTP-E. Patients with ALTP had shorter OS (13.0 vs 17.1 months, p = 0.047) compared with those without ALTP. Factors associated with an increased likelihood of ALTP included the amount of bone marrow infiltrated by tumor at the index level, amount of residual epidural disease following separation surgery, and prior receipt of radiotherapy at the index level (p < 0.05). Subgroup analysis revealed that primary tumor type, amount of preoperative epidural disease, time elapsed between surgery and radiosurgery, and prior receipt of radiotherapy at the index level were significantly associated with ALTP-E (p < 0.05).

CONCLUSIONS

To the authors' knowledge, this study is the first to identify possible risk factors for ALTP, and they suggest that it may be associated with shorter OS in patients receiving surgery followed by radiosurgery for MESCC. Future studies with higher power should be conducted to further characterize factors associated with ALTP in this population.

Novel Strategy of Ventral Dural Repair for Idiopathic Thoracic Spinal Cord Herniation: Report of Outcomes and Review of Techniques

BACKGROUND

Idiopathic ventral thoracic spinal cord herniation is a rare condition that usually presents with progressive myelopathy or Brown-Séquard syndrome. More than 100 cases have been reported with significant variance in surgical treatment strategies and likewise, significant variance in patient outcomes. Although laminectomy has often been used, to date, there is no consensus regarding the optimal surgical approach or strategy for ventral dural repair.

OBJECTIVE

To report and illustrate a novel approach to repair the ventral dural defect with more than 2 yr of clinical follow-up. The specific approach and graft used are both detailed.

METHODS

A retrospective chart review of all known cases of idiopathic spinal cord herniation at the Cleveland Clinic over the last 15 yr was performed. Postoperative outcome scores (including the Japanese Orthopedic Association score, European Myelopathy score, and Nurick) were calculated preoperatively and postoperatively.

RESULTS

A total of 5 patients were identified. Four of five patients improved clinically after surgery and 1 patient remained unchanged at last follow-up (average 23.2 mo, range 12-60 mo). There were no complications. All patients had postoperative magnetic resonance imaging demonstrating realignment of the spinal cord and no recurrence of tethering.

CONCLUSION

A unilateral dorsolateral, transpedicular approach combined with laminectomy provides excellent exposure for ventral or ventrolateral dural defects associated with idiopathic spinal cord herniation and minimizes spinal cord manipulation. A collagen matrix graft used as an onlay between the spinal cord and ventral dural defect is a safe and effective option for ventral dural repair.

Spinal Dural Arteriovenous Fistula: Diagnosis, Outcomes, and Prognostic Factors

OBJECTIVE

Typically, the clinical presentation of a spinal dural arteriovenous fistula (SDAVF) will be insidious, with patients' symptoms regularly attributed to other conditions. Although previous studies have characterized the neurologic outcomes after treatment for SDAVFs, little is known about the pretreatment patient characteristics associated with poor and/or positive patient outcomes. We sought to characterize the pretreatment patient demographics, diagnostic history, and neurologic outcomes of patients treated for SDAVFs and to identify the patient factors predictive of these outcomes.

METHODS

The medical records of patients who had been treated for SDAVFs from 2006 to 2018 across 1 healthcare system were retrospectively analyzed. Neurologic status was assessed both before and after intervention using the Aminoff-Logue scales for gait and micturition disturbances.

RESULTS

Of 46 total patients, 16 (35%) had a documented misdiagnosis. Patients with a history of misdiagnosis had had a significantly longer symptom duration before treatment compared with those without a misdiagnosis (median, 2.3 vs. 0.9 years; P = 0.018). A shorter symptom duration before intervention was significantly associated with both improved motor function (median, 0.8 vs. 3.1 years; P = 0.001) and improved urinary function (median, 0.8 vs. 2.2 years; P = 0.040) after intervention.

CONCLUSIONS

Misdiagnosis has been relatively common in patients with SDAVFs and contributes to delays in treatment. Delays in diagnosis and treatment of SDAVFs appear to be associated with worse clinical outcomes for patients who, ultimately, receive treatment.

Spine radiosurgery in adolescents and young adults: early outcomes and toxicity in patients with metastatic Ewing sarcoma and osteosarcoma

OBJECTIVE

There are limited data on spine stereotactic radiosurgery (SRS) in treating adolescent and young adult (AYA) patients. SRS has the advantages of highly conformal radiation dose delivery in the upfront and retreatment settings, means for dose intensification, and administration over a limited number of sessions leading to a decreased treatment burden. In this study, the authors report the oncological and toxicity outcomes for AYA patients with metastatic sarcoma treated with spine radiosurgery and provide clinicians a guide for considerations in dose, volume, and fractionation.

METHODS

An institutional review board-approved database of patients treated with SRS in the period from October 2014 through December 2018 was queried. AYA patients, defined by ages 15-29 years, who had been treated with SRS for spine metastases from Ewing sarcoma or osteosarcoma were included in this analysis. Patients with follow-ups shorter than 6 months after SRS were excluded. Local control, overall survival, and toxicity were reported.

RESULTS

Seven patients with a total of 11 treated lesions were included in this study. Median patient age was 20.3 years (range 15.1-26.1 years). Three patients had Ewing sarcoma (6 lesions) and 4 patients had osteosarcoma (5 lesions). The median dose delivered was 35 Gy in 5 fractions (range 16-40 Gy, 1-5 fractions). The median follow-up was 11.1 months (range 6.8-26.0 months). Three local failures were observed within the follow-up period. No acute grade 3 or greater toxicity was observed. One patient developed late grade 3 toxicity consisting of radiation enteritis. This patient had previously received radiation to an overlapping volume with conventional fractionation. SRS re-irradiation for this patient was also performed concurrently with chemotherapy administration. No late grade 4 or higher toxicities were observed. No pain flare or vertebral compression fracture was observed. Three patients died within the follow-up period.

CONCLUSIONS

SRS for spine metastases from Ewing sarcoma and osteosarcoma can be considered as a treatment option in AYA patients and is associated with acceptable toxicity rates. Further studies must be conducted to determine long-term local control and toxicity for this treatment modality.

Development and implementation of a comprehensive spine surgery enhanced recovery after surgery protocol: the Cleveland Clinic experience

Enhanced recovery after surgery (ERAS) protocols have been shown to be effective at reducing perioperative morbidity and costs while improving outcomes. To date, spine surgery protocols have been limited in scope, focusing only on specific types of procedures or specific parts of the surgical episode. The authors describe the creation and implementation of one of the first comprehensive ERAS protocols for spine surgery. The protocol is unique in that it has a comprehensive perioperative paradigm encompassing the entire surgical period that is tailored based on the complexity of each individual spine patient.

Gastrostomy tube placement increases the risk of ventriculoperitoneal shunt infection: a multiinstitutional study

OBJECTIVEGastrostomy tube placement can temporarily seed the peritoneal cavity with bacteria and thus theoretically increases the risk of shunt infection when the two procedures are performed contemporaneously. The authors hypothesized that gastrostomy tube placement would not increase the risk of ventriculoperitoneal shunt infection. The object of this study was to test this hypothesis by utilizing a large patient cohort combined from multiple institutions.METHODSA retrospective study of all adult patients admitted to five institutions with a diagnosis of aneurysmal subarachnoid hemorrhage between January 2005 and January 2015 was performed. The primary outcome of interest was ventriculoperitoneal shunt infection. Variables, including gastrostomy tube placement, were tested for their association with this outcome. Standard statistical methods were utilized.RESULTSThe overall cohort consisted of 432 patients, 47% of whom had undergone placement of a gastrostomy tube. The overall shunt infection rate was 9%. The only variable that predicted shunt infection was gastrostomy tube placement (p = 0.03, OR 2.09, 95% CI 1.07-4.08), which remained significant in the multivariate analysis (p = 0.04, OR 2.03, 95% CI 1.04-3.97). The greatest proportion of shunts that became infected had been placed more than 2 weeks (25%) and 1-2 weeks (18%) prior to gastrostomy tube placement, but the temporal relationship between shunt and gastrostomy was not a significant predictor of shunt infection.CONCLUSIONSGastrostomy tube placement significantly increases the risk of ventriculoperitoneal shunt infection.

Clinical Outcomes Following Surgical Management of Coexisting Parkinson Disease and Cervical Spondylotic Myelopathy

BACKGROUND

Distinguishing the causes of weakness and gait instability in patients with Parkinson disease (PD) and cervical spondylotic myelopathy (CSM) is a diagnostic and therapeutic challenge due to symptomatic similarities. No study has reported outcomes following decompression in patients with PD and CSM.

OBJECTIVE

To report outcomes following cervical decompression for patients with coexisting PD and CSM.

METHODS

A retrospective matched cohort study of all patients with PD and CSM undergoing cervical decompression at a tertiary-care center between January 1996 and December 2014 was conducted. PD patients were matched to patients with CSM alone by age, gender, American Society of Anesthesiologists classification, and operative parameters. Myelopathy was assessed by Nurick and modified Japanese Orthopaedic Association (mJOA) scales. The effect of PD on mJOA was modeled using multivariable regression.

RESULTS

Twenty-one matched pairs were included. PD patients experienced poorer improvement in Nurick (0.0 vs -1.0, P < .01) and mJOA (0.9 vs 2.5, P < .01) composite scores. However, no significant changes in absolute improvement in the upper extremity motor, upper extremity sensory, or sphincter mJOA components were observed. Multivariable regression identified PD as a significant predictor of decreased improvement in mJOA (β = -0.89, P < .01) and failure to achieve a minimal clinically important difference in change in mJOA (OR 0.18, P = .03).

CONCLUSION

This study is the first to characterize outcomes following cervical decompression in patients with PD and CSM. PD patients experienced symptomatic improvement but less overall improvement in myelopathy compared to controls. However, PD patients demonstrated improvement in upper extremity motor, upper extremity sensory, and sphincter symptoms no worse than control patients.

Quality of life outcomes following cervical decompression for coexisting Parkinson's disease and cervical spondylotic myelopathy

BACKGROUND CONTEXT

Coexisting Parkinson's disease (PD) and cervical spondylotic myelopathy (CSM) presents a diagnostic and therapeutic challenge due to symptomatic similarities between the diseases. Whereas CSM patients are routinely treated with surgery, PD patients face poorer outcomes following spine surgery. No studies have investigated the quality of life (QOL) outcomes following decompression in coexisting PD and CSM.

PURPOSE

The purpose of the present study was to characterize QOL outcomes for patients with coexisting PD and CSM following cervical decompression.

STUDY DESIGN/SETTING

This is a matched cohort study at a single tertiary-care center.

PATIENT SAMPLE

Patients with coexisting PD and CSM undergoing cervical decompression between June 2009 and December 2014 were included. These patients were matched to controls with CSM alone by age, gender, American Society of Anesthesiologists classification, Modified Japanese Orthopaedic Association scores, and operative parameters.

OUTCOME MEASURES

The primary outcome measure was QOL outcomes assessed by change in the EuroQol 5-Dimensions (EQ-5D), Pain Disability Questionnaire (PDQ), and Patient Health Questionnaire-9 (PHQ-9) at last follow-up (LFU). Change in QOL exceeding the minimal clinically important difference (MCID) was secondary.

METHODS

QOL data were collected using the institutional prospectively collected database of patient-reported health status measures. Simple and multivariable regressions were used to assess the impact of PD upon change in QOL.

RESULTS

Eleven PD patients were matched to 44 controls. Control patients experienced QOL improvement across all three measures, whereas PD patients only improved with respect to PDQ(89.9-80.7, p=.03). Despite no significant differences in preoperative QOL, PD patients experienced poorer QOL at LFU in EQ-5D (0.526 vs. 0.707, p=.01) and PDQ (80.7 vs. 51.4, p=.03), and less frequently achieved an EQ-5D MCID (18% vs. 57%, p=.04). However, no differences in the achievement of an MCID in PDQ or PHQ-9 were observed between cohorts. Multivariable regression identified PD as a significant independent predictor of poorer improvement in EQ-5D (β=-0.09, p<.01) and failure to achieve an EQ-5D MCID (odds ratio: 0.08, p<.01).

CONCLUSIONS

This is the first study to characterize QOL outcomes following cervical decompression for patients with coexisting PD and CSM. Although myelopathy may have been less severe among PD patients, a significant reduction in pain-related disability was observed following decompression. However, PD predicted diminished improvement in overall QOL measured by the EQ-5D.

Morphological Transformation of Giant-Cell Tumor of Bone After Treatment with Denosumab: A Case Report

CASE

Denosumab, an inhibitor of RANKL (receptor activator of nuclear factor κ-B ligand), was recently introduced for the treatment of giant-cell tumor of bone (GCTB). We describe the clinical, radiographic, and histological features of a GCTB of the spine in a 24-year-old woman that progressed after neoadjuvant treatment with denosumab. Disappearance of the multinuclear osteoclastic giant cells was accompanied by newly formed woven bone, which was deposited in interconnected strands with a prominent fibrovascular stroma that was histologically and radiographically similar to that of an osteoblastoma.

CONCLUSION

Pathologists, radiologists, and surgeons should be aware of this post-treatment transformation to avoid misdiagnosis.

Molecular and clinical prognostic factors for favorable outcome following surgical resection of adult intramedullary spinal cord astrocytomas

OBJECTIVE

Intramedullary spinal cord astrocytomas are uncommon but important entities. Aggressive surgical resection is believed to be critical to prevent subsequent neurological deterioration; however, the prognostic significance of numerous patient and molecular variables remains unclear. We sought to investigate the clinical and molecular factors associated with outcomes following surgical resection of adult spinal cord astrocytomas.

METHODS

A consecutive retrospective chart review of all patients who underwent intramedullary spinal cord astrocytoma resection at a single tertiary-care institution between January 1996 and December 2011 was conducted. Molecular data collected included p53 mutation status, proliferative activity (Ki-67), 1p/19q chromosome loss, and EGFR amplification. Multivariable logistic and Cox proportional hazards regression were used to identify variable associated with postoperative outcomes.

RESULTS

Among 13 patients undergoing surgical resection followed for a median of 54 months, 54% experienced improvement in neurological status, while 15% remained unchanged and 31% deteriorated. Following resection, the 5-year local control (LC), progression-free survival (PFS), and overall survival (OS) rates were 83%, 63%, and 83%. Median PFS time was found to be 5.6 years. Multivariable regression revealed limited characteristics associated with postoperative outcomes, though no molecular characteristics were found to be prognostic. Older age at surgery predicted decreased probability of PFS (HR 0.91, 95% CI 0.81-0.99, p=0.03) and trended towards predicting lack of neurological improvement (OR 0.94, 95% CI 0.83-1.02, p=0.21) and decreased OS (HR 0.93, 95% CI 0.81, 1.03, p=0.15). Preoperative motor symptoms (OR 0.12, 95% CI <0.01-1.91, p=0.14) and adjuvant chemotherapy (OR 0.07, 95% CI <0.01-1.82, p=0.12) also trended towards predicting lack of neurological improvement.

CONCLUSION

Age was the only patient variable found to have a statistically significant association with profession-free survival and no other factors were significantly associated with postoperative outcomes. These findings were limited by a relatively small sample size; thus, future studies with increased power investigating the prognostic effects of molecular characteristics could provide further clarity in identifying patients most likely to benefit from surgical resection.

Spinal cord stimulation: a review of the safety literature and proposal for perioperative evaluation and management

BACKGROUND CONTEXT

There is currently no consensus on appropriate perioperative management of patients with spinal cord stimulator implants. Magnetic resonance imaging (MRI) is considered safe under strict labeling conditions. Electrocautery is generally not recommended in these patients but sometimes used despite known risks.

PURPOSE

The aim was to discuss the perioperative evaluation and management of patients with spinal cord stimulator implants.

STUDY DESIGN

A literature review, summary of device labeling, and editorial were performed, regarding the safety of spinal cord stimulator devices in the perioperative setting.

METHODS

A literature review was performed, and the labeling of each Food and Drug Administration (FDA)-approved spinal cord stimulation system was reviewed. The literature review was performed using PubMed and the FDA website (www.fda.gov).

RESULTS

Magnetic resonance imaging safety recommendations vary between the models. Certain systems allow for MRI of the brain to be performed, and only one system allows for MRI of the body to be performed, both under strict labeling conditions. Before an MRI is performed, it is imperative to ascertain that the system is intact, without any lead breaks or low impedances, as these can result in heating of the spinal cord stimulation (SCS) and injury to the patient. Monopolar electrocautery is generally not recommended for patients with SCS; however, in some circumstances, it is used when deemed required by the surgeon. When cautery is necessary, bipolar electrocautery is recommended. Modern electrocautery units are to be used with caution as there remains a risk of thermal injury to the tissue in contact with the SCS. As with MRI, electrocautery usage in patients with SCS systems with suspected breaks or abnormal impedances is unsafe and may cause injury to the patient.

CONCLUSIONS

Spinal cord stimulation is increasingly used in patients with pain of spinal origin, particularly to manage postlaminectomy syndrome. Knowledge of the safety concerns of SCS and appropriate perioperative evaluation and management of the SCS system can reduce risks and improve surgical planning.

Circumferential intrathecal ossification in oculoleptomeningeal amyloidosis

Oculoleptomeningeal amyloidosis (OLMA) is a variant of familial amyloidosis that results in amyloid deposition in the vitreous and leptomeninges. A 60-year-old woman with a history of OLMA presented to the emergency department for obtundation secondary to apparent shunt malfunction and lower extremity weakness. CT imaging of her spinal axis showed high attenuation material present intradurally from the mid cervical level extending through the thoracic and lumbar spine in the extramedullary space. MRI demonstrated circumferential signal enhancement surrounding the entire spinal cord. The patient underwent open biopsy at L3-L5. Upon opening the dura, a homogenous intradural ossification encasing the nerve roots was seen. Given the extent of the ossification, no further attempt at decompression was performed. Microscopic review of the biopsy sample revealed sclerotic bone with focal amorphous material consistent with amyloid. To our knowledge this is the first case report of a patient with OLMA presenting with extensive circumferential intrathecal ossification from amyloid deposition. Despite examples of leptomeningeal enhancement in patients with OLMA, extensive intradural ossification is a finding that has not been previously reported radiographically or post mortem.

Bow hunter's syndrome secondary to bilateral dynamic vertebral artery compression

Bow hunter's syndrome is a condition in which vertebrobasilar insufficiency is resultant from head rotation, clinically manifested by presyncopal sensation, syncope, dizziness, and nausea. It is usually diagnosed clinically, with supporting vascular imaging demonstrating an occluded or at the very least compromised unilateral vertebral artery, while the dominant vertebral artery remains patent in the neutral position. Dynamic imaging is utilized to confirm the rotational compression of the dominant vertebral artery. We present the rare case of a patient with typical Bow hunter's symptoms, bilaterally patent vertebral arteries on neutral imaging, and bilateral compromise with head rotation. Our patient underwent posterior decompression of the culprit atlanto-axial transverse foramen and subaxial cervical fusion, with resolution of his symptoms. Our patient exemplifies the possibility of bilateral dynamic vertebral artery occlusion. We show that Bow hunter's syndrome cannot be ruled out in the setting of bilaterally patent vertebral arteries on neutral imaging and that severe cervical spondylosis should impart further clinical suspicion of this unusual phenomenon.

Risk to the vertebral artery during C-2 translaminar screw placement: a thin-cut computerized tomography angiogram-based morphometric analysis: clinical article

OBJECT

The goal of this study was to characterize the anatomy relevant to placement of crossing C-2 translaminar screws, including morphometric data, and to evaluate the risk of violating the vertebral artery (VA) during the screw placement. Placement of bilateral crossing C-2 translaminar screws has become an increasingly popular method for dorsal C-2 instrumentation as it is felt to avoid the known risk of VA injury associated with C1-2 transarticular screw fixation and C-1 lateral mass-C-2 pars screw fixation.

METHODS

The source images from 50 CT angiograms of the neck obtained from October to November 2007 were studied. Digital imaging software was used to measure lamina thickness and maximum screw length, perform angulation of screw trajectories in the axial plane, and evaluate the potential for VA injury. In cases where the VA could be injured, the distance between the maximal screw length and artery was measured. Logistic regression was performed to evaluate lamina width, axial angle, and screw length for predicting the potential for VA injury.

RESULTS

Mean lamina thickness, axial angle, and maximal screw length were determined for 100 laminae, and a potential for VA injury was noted in 55 laminae. The anatomically defined ideal screw length was longer in laminae with potential for VA injury than in laminae with no apparent risk (35.2 vs 33.6 mm, p = 0.0131). Only increasing optimal screw length was noted to be a statistically significant predictor of potential VA injury (p = 0.0159). The "buffer zone" (the distance between an optimally placed screw and the VA) was 5.6 ± 1.9 mm (mean ± SD, range 1.8-11.4 mm). A screw limited to 28 mm in length appeared to be safe in all laminae studied.

CONCLUSIONS

Crossing C-2 translaminar screws have been reported to be safe and effective. In addition to morphometric characteristics, the authors have found that screws placed in this trajectory could jeopardize the vertebral arteries in the foramen transversarium or the C1-2 interval. A C-2 translaminar screw limited to 28 mm in length appeared to be safe in all 100 screw trajectories studied in this series.

Dorsal versus ventral surgery for cervical ossification of the posterior longitudinal ligament: considerations for approach selection and review of surgical outcomes

Ossification of the posterior longitudinal ligament is a common cause of radiculopathy and myelopathy that often requires surgery to achieve decompression of the neural elements. With the evolution of surgical technique and a greater understanding of the biomechanics of cervical deformity, the criteria for selecting one approach over the other has been the subject of increased study and remains controversial. Ventral approaches typically consist of variations of the cervical corpectomy, whereas dorsal approaches include a wide range of techniques including laminoplasty, laminectomy, and laminectomy with instrumented fusion. Herein, the features and limitations of these approaches are reviewed with an emphasis on complications and outcomes.

Comparative Effectiveness of Ventral vs Dorsal Surgery for Cervical Spondylotic Myelopathy

BACKGROUND:

Cervical spondylotic myelopathy (CSM) is the most common cause of spinal cord dysfunction.

OBJECTIVE:

To determine the feasibility of a randomized clinical trial comparing the clinical effectiveness and costs of ventral vs dorsal decompression with fusion surgery for treating CSM.

METHODS:

A nonrandomized, prospective, clinical pilot trial was conducted. Patients ages 40 to 85 years with degenerative CSM were enrolled at 7 sites over 2 years (2007–2009). Outcome assessments were obtained preoperatively and at 3 months, 6 months, and 1 year postoperatively. A hospital-based economic analysis used costs derived from hospital charges and Medicare cost-to-charge ratios.

RESULTS:

The pilot study enrolled 50 patients. Twenty-eight were treated with ventral fusion surgery and 22 with dorsal fusion surgery. The average age was 61.6 years. Baseline demographics and health-related quality of life (HR-QOL) scores were comparable between groups; however, dorsal surgery patients had significantly more severe myelopathy (P &lt; .01). Comprehensive 1-year follow-up was obtained in 46 of 50 patients (92%). Greater HR-QOL improvement (Short-Form 36 Physical Component Summary) was observed after ventral surgery (P = .05). The complication rate (16.6% overall) was comparable between groups. Significant improvement in the modified Japanese Orthopedic Association scale score was observed in both groups (P &lt; .01). Dorsal fusion surgery had significantly greater mean hospital costs ($29 465 vs $19 245; P &lt; .01) and longer average length of hospital stay (4.0 vs 2.6 days; P &lt; .01) compared with ventral fusion surgery.

CONCLUSION:

Surgery for treating CSM was followed by significant improvement in disease-specific symptoms and in HR-QOL. Greater improvement in HR-QOL was observed after ventral surgery. Dorsal fusion surgery was associated with longer length of hospital stay and higher hospital costs. The pilot study demonstrated feasibility for a larger randomized clinical trial.

Idiopathic ventral spinal cord herniation: a rare presentation of tethered cord

Idiopathic ventral spinal cord herniation is a rare condition that has been increasingly reported in the last decade. The natural history and optimal management have yet to be defined. Therefore, debate exists regarding the pathogenesis and surgical management of this condition. The purpose of this review article is to further educate neurosurgeons about the surgical techniques and outcomes associated with treating this rare and often misdiagnosed condition.

Postoperative complications associated with dural substitutes in suboccipital craniotomies

OBJECTIVE

Dural replacements are used in cranial surgery when primary closure of native dura is not possible. The goal is to recreate a watertight barrier to prevent cerebrospinal fluid leakage with few associated complications. We reviewed a single-institution experience with a variety of dural substitutes in posterior fossa neurosurgery, for which higher complication rates are well described.

METHODS

Patients were screened for suboccipital posterior fossa neurosurgery between November 2005 and April 2007. Surgical logs were reviewed for diagnosis, procedure, and use of dural replacement. Clinical courses were reviewed for hydrodynamic complications, including delayed hydrocephalus, clinically significant pseudomeningocele, aseptic meningitis, and persistent cerebrospinal leakage.

RESULTS

One hundred twenty-eight patients were included, and a dural replacement was used in 106. Overall, the complication rate was 21.9% (28 patients). Complications were seen for acellular human dermis in 33.3%, for collagen matrix in the original formulation in 18.2%, for the reformulation in 16.9%, for the suturable formulation in 50%, for nonautologous materials in 24%, and for no dural replacement in 16.7%. Univariate and multivariate analysis demonstrated that hydrodynamic complications were associated with use of the suturable collagen matrix (odds ratio, 10.8; 95% confidence interval, 2.5-46.1; P = 0.0014) and trended with use of acellular human dermis (odds ratio, 4.6; 95% confidence interval, 0.9-23.1; P = 0.06).

CONCLUSION

The increased risk of hydrodynamic complications associated with suboccipital neurosurgery is modified by choice of dural replacement. Similar complication rates were seen for most materials with a variety of primary abnormalities, with the exception of suturable bovine collagen matrix, with hydrodynamic complications in 50% of patients.

Surgical Management of Neck and Low Back Pain

Surgical intervention for neck pain and low back pain may be of benefit to some patients. It should be considered, however, only in cases where medical management has failed and there is a clearly identifiable anatomic lesion that likely is the pain generator. Indications, preoperative evaluation, and common surgical procedures are reviewed.

Regional instability following cervicothoracic junction surgery

Object

The cervicothoracic junction (CTJ) is the transitional region between the cervical and thoracic sections of the spinal axis. Because it is a transitional zone between the mobile lordotic cervical and rigid kyphotic thoracic spines, the CTJ is a region of potential instability. This potential for instability may be exaggerated by surgical intervention.

Methods

A retrospective review of all patients who underwent surgery involving the CTJ in the Department of Neurosurgery at the Cleveland Clinic Foundation during a 5-year period was performed. The CTJ was strictly defined as encompassing the C-7 vertebra and C7–T1 disc interspace. Patients were examined after surgery to determine if treatment had failed. Failure was defined as construct failure, deformity (progression or de novo), or instability. Variables possibly associated with treatment failure were analyzed. Statistical comparisons were performed using the Fisher exact test.

Between January 1998 and November 2003, 593 CTJ operations were performed. Treatment failed in 14 patients. Of all variables studied, failure was statistically associated with laminectomy and multilevel ventral corpectomies with fusion across the CTJ. Other factors statistically associated with treatment failure included histories of cervical surgery, tobacco use, and surgery for the correction of deformity.

Conclusions

The CTJ is a vulnerable region, and this vulnerability is exacerbated by surgery. Results of the present study indicate that laminectomy across the CTJ should be supplemented with instrumentation (and fusion). Multilevel ventral corpectomies across the CTJ should also be supplemented with dorsal instrumentation. Supplemental instrumentation should be considered for patients who have undergone prior cervical surgery, have a history of tobacco use, or are undergoing surgery for deformity correction.

Anterior cervical plating

Although anterior cervical instrumentation was initially used in cervical trauma, because of obvious benefits, indications for its use have been expanded over time to degenerative cases as well as tumor and infection of the cervical spine. Along with a threefold increase in incidence of cervical fusion surgery, implant designs have evolved over the last three decades. Observation of graft subsidence and phenomenon of stress shielding led to the development of the new generation dynamic anterior cervical plating systems. Anterior cervical plating does not conclusively improve clinical outcome of the patients, but certainly enhances the efficacy of autograft and allograft fusion and lessens the rate of pseudoarthrosis and kyphosis after multilevel discectomy and fusions. A review of biomechanics, surgical technique, indications, complications and results of various anterior cervical plating systems is presented here to enable clinicians to select the appropriate construct design.

Biomechanics of metastatic spine cancer

The spine is the most common site of skeletal metastases. Most of these occur within the vertebral body, thereby predisposing patients to pathologic fracture. The risk of fracture is related to the extent of bony destruction, location of the lesion, and inherent bone quality. The regional variation in spine anatomy exposes the cervical,thoracic, and lumbar spines to different forces,resulting in varying fracture types.

Outcome after the treatment of spinal dural arteriovenous fistulae: a contemporary single-institution series and meta-analysis

OBJECTIVE

Spinal dural arteriovenous fistulae (Type I spinal AVMs) are the most common type of spinal vascular malformations. The optimal treatment strategy has yet to be defined, and endovascular embolization is being offered with increasing frequency. A 7-year single-institution retrospective review of outcome with surgical management of Type I spinal AVMs is presented along with a meta-analysis of existing literature.

METHODS

For the institutional analysis, a retrospective review of all patients who underwent treatment at our institution for Type I spinal AVMs was performed. Between 1995 and the present (the time frame during which endovascular treatments were available), 19 consecutive patients were treated. Follow-up was performed by clinical examination or telephone interview, and functional status was measured by use of the Aminoff-Logue score. For the meta-analysis, a MEDLINE search between 1966 and the present was performed for surgical, endovascular, or combined treatment of spinal dural arteriovenous fistula. These series were included in a meta-analysis to evaluate success and failure rates, complications, and functional outcome. Specifically, embolization and microsurgery were compared.

RESULTS

For the institutional analysis, 18 of 19 patients were available for long-term follow-up after surgery. There were no surgical failures, but one complication was seen. Patients demonstrated a statistically significant improvement in gait and bladder function after surgery. For the meta-analysis, 98% of those patients treated with microsurgery had their dural arteriovenous fistulae successfully obliterated after the initial treatment, compared with only 46% with embolization, as judged by radiographic or clinical follow-up. 89% percent of patients demonstrated improvement or stabilization in neurological symptoms after surgical treatment. Few complications were demonstrated with either surgery or embolization.

CONCLUSION

At this point, surgery seems to be superior to embolization for the management of spinal dural arteriovenous fistula. The fistula is usually obliterated after the initial treatment, with few clinical or radiographic recurrences. The majority of patients either improve or stabilize after treatment. Few worsen, and the morbidity is minimal. It is reasonable to attempt initial embolization, especially at the time of the initial diagnostic spinal angiogram. The treating physicians and patients should be aware of the high chance of recurrence, and patients may ultimately require surgery or repeat embolization. After endovascular therapy, patients are committed to repeat angiography and probably embolization. For these reasons, it is the authors' opinion that surgery should be used as the first-line therapy for spinal dural arteriovenous fistulae.

Cervical spinal cord delivery of a rabies G protein pseudotyped lentiviral vector in the SOD-1 transgenic mouse. Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2004

OBJECT

Lentiviral vectors may constitute a vehicle for long-term therapeutic gene expression in the spinal cord. In amyotrophic lateral sclerosis, spinal cord sclerosis and altered axonal transport pose barriers to therapeutic gene distribution. In the present study the authors characterize gene expression distribution and the behavioral impact of the rabies G (RabG) protein pseudotyped lentiviral vector EIAV.LacZ through cervical spinal cord injection in control and Cu/Zn superoxide dismutase-1 (SOD-1) transgenic mice.

METHODS

Seven-week-old SOD-1 transgenic mice and their wild-type littermates underwent exposure of the cervicomedullary junction and microinjection of RabG.EIAV.LacZ or vehicle. The Basso-Beattie-Bresnahan locomotor score, grip strength meter, and Rotarod assays were used to assess the effects of disease progression, spinal cord microinjection, and lentiviral gene expression. Spinal cords were removed when the mice were in the terminal stage of the disease. The distribution of LacZ gene expression was histologically evaluated and quantified. Direct cervical spinal cord microinjection of RabG.EIAV.LacZ results in extensive central nervous system uptake in SOD-1 transgenic mice; these findings were statistically similar to those in wild-type mice (p > 0.05). Gene expression lasts for the duration of the animal's survival (132 days). The SOD-1 mutation does not prevent retrograde axonal transport of the vector. Three behavioral assays were used to demonstrate that long-term gene expression does not alter sensorimotor function. In comparison with normative data, vector injection and transgene expression do not accelerate disease progression.

CONCLUSIONS

Direct spinal cord injection of RabG.EIAV vectors represents a feasible method for delivering therapeutic genes to upper cervical spinal cord and brainstem motor neurons. Distribution is not affected by the SOD-1 mutation or disease phenotype.

Bilateral tentorial subdural hematoma without subarachnoid hemorrhage secondary to anterior communicating artery aneurysm rupture: a case report and review of the literature

A case of acute subdural hematoma over the tentorium secondary to rupture of an anterior communicating artery aneurysm is reported. A 42-year-old female patient presented with acute-onset, severe bifrontal and retro-orbital headache. CT revealed only symmetric thickening of the tentorium. MR imaging revealed the presence of a 10-mm anterior communicating artery aneurysm, which was confirmed by digital subtraction angiography. The radiologic findings and possible mechanisms of this hemorrhage are discussed.

Protective effect of rotavirus VP6-specific IgA monoclonal antibodies that lack neutralizing activity

Rotaviruses are the leading cause of severe gastroenteritis and dehydrating diarrhea in young children and animals worldwide. A murine model and "backpack tumor" transplantation were used to determine the protective effect of antibodies against VP4(an outer capsid viral protein) and VP6(a major inner capsid viral protein). Only two non-neutralizing immunoglobulin A (IgA) antibodies to VP6 were capable of preventing primary and resolving chronic murine rotavirus infections. These antibodies were not active, however, when presented directly to the luminal side of the intestinal tract. These findings support the hypothesis that in vivo intracellular viral inactivation by secretory IgA during transcytosis is a mechanism of host defense against rotavirus infection.

Cleavage of rotavirus VP4 in vivo

The infectivity of rotavirus particles is dependent on proteolytic cleavage of the outer capsid protein, VP4, at a specific site. This cleavage event yields two fragments, identified as VP5* and VP8*. It has been hypothesized that the particle is more stable, but non-infectious, when VP4 is in the uncleaved state. Uncleaved VP4 and the resultant increased stability might be advantageous for the virus to resist environmental degradation until it infects a susceptible host. When VP4 is cleaved in the lumen of the host's gastrointestinal tract, the virus particle would become less stable but more infectious. To test this hypothesis, a series of experiments was undertaken to analyse the cleavage state of VP4 on virus shed by an infected host into the environment. Immunoblots of intestinal wash solutions derived from infant and adult BALB/c mice infected with a virulent cell culture-adapted variant of the EDIM virus (EW) or wild-type murine rotavirus EDIM-Cambridge were analysed. Virtually all of the VP4 in these samples was in the cleaved form. Moreover, cell culture titration of trypsin-treated and untreated intestinal contents from pups infected with EW indicated that excreted virus is fully activated prior to trypsin addition. It was also observed that trypsin-activated virus has no disadvantage in initiating infection in naive animals over virions containing an intact VP4. These studies indicate that VP4 is cleaved upon release from the intestinal cell and that virus shed into the environment does not have an intact VP4.

Analyses of homologous rotavirus infection in the mouse model

The group A rotaviruses are significant human and veterinary pathogens in terms of morbidity, mortality, and economic loss. Despite its importance, an effective vaccine remains elusive due at least in part to our incomplete understanding of rotavirus immunity and protection. Both large and small animal model systems have been established to address these issues. One significant drawback of these models is the lack of well-characterized wild-type homologous viruses and their cell culture-adapted variants. We have characterized four strains of murine rotaviruses, EC, EHP, EL, and EW, in the infant and adult mouse model using wild-type isolates and cell culture-adapted variants of each strain. Wild-type murine rotaviruses appear to be equally infectious in infant and adult mice in terms of the intensity and duration of virus shedding following primary infection. Spread of infection to naive cagemates is seen in both age groups. Clearance of shedding following primary infection appears to correlate with the development of virus-specific intestinal IgA. Protective immunity is developed in both infant and adult mice following oral infection as demonstrated by a lack of shedding after subsequent wild-type virus challenge. Cell culture-adapted murine rotaviruses appear to be highly attenuated when administered to naive animals and do not spread efficiently to nonimmune cagemates. The availability of these wild-type and cell culture-adapted virus preparations should allow a more systematic evaluation of rotavirus infection and immunity. Furthermore, future vaccine strategies can be evaluated in the mouse model using several fully virulent homologous viruses for challenge.