Neurosurgery Blog


Daily bibliographic review of the Neurosurgery Department. La Fe University Hospital. Valencia, Spain

Expandable vs Static Cages in Transforaminal Lumbar Interbody Fusion

Neurosurgery 81:69–74, 2017

One criticism of transforaminal lumbar interbody fusion (TLIF) is the inability to increase segmental lordosis (SL). Expandable interbody cages are a relatively new innovation theorized to allow improvement in SL.

OBJECTIVE: To compare changes in SL and lumbar lordosis (LL) after TLIF with nonexpandable vs expandable cages. METHODS: We performed a retrospective cohort study of patients who were ≥18 years old and underwent single-level TLIF between 2011 and 2014. Patients were categorized by cage type (static vs expandable). Primary outcome of interestwas change in SL and LL from preoperative values to those at 1 month and 1 year postoperatively.

RESULTS: A total of 89 patients were studied (48 nonexpandable group, 41 expandable group). Groups had similar baseline characteristics. For SL, median (interquartile range) improvement was 3◦ for nonexpandable and 2◦ for expandable (unadjusted, P = .09; adjusted, P = .68) at 1 month postoperatively, and 3◦ for nonexpandable and 1◦ for expandable (unadjusted, P=.41; adjusted, P=.28) at 1 year postoperatively. For LL, median improvement was 1◦ for nonexpandable and 2◦ for expandable (unadjusted, P = .20; adjusted, P = .21), and 2◦ for nonexpandable and 5◦ for expandable (unadjusted, P = .15; adjusted, P=.51) at 1 year postoperatively. After excluding parallel expandable cages, there was still no difference in SL or LL improvement at 1month or 1 year postoperatively between static and expandable cages (both unadjusted and adjusted, P > .05).

CONCLUSION: Patients undergoing single-level TLIF experienced similar improvements in SL and LL regardless of whether nonexpandable or expandable cages were placed.

Does Intrawound Vancomycin Application During Spine Surgery Create Vancomycin-Resistant Organism?

Neurosurgery (2017) 80 (5): 746-753

Surgical site infection (SSI) following spine surgery is a morbid and expensive complication. The use of intrawound vancomycin is emerging as a solution to reduce SSI. The development of vancomycin-resistant pathogens is an understandable concern.

OBJECTIVE: To determine the occurrence of vancomycin-resistant SSI in patients with and without use of intrawound vancomycin.

METHODS: Patients undergoing elective spine surgery were dichotomized based on whether intrawound vancomycin was applied. Outcome was occurrence of SSI requiring return to the operating room within postoperative 90 days. The intrawound culture and vancomycin minimal inhibitory concentrations (MIC) were reviewed. Analyses were conducted to compare the pathogen profile and MIC for vancomycin in patients who received vancomycin and those who did not.

RESULTS: Of the total 2802 patients, 43% (n = 1215) had intrawound vancomycin application during the index surgery. The use of vancomycin was associated with significantly lower deep SSI rates (1.6% [n = 20] vs 2.5% [n = 40], P = .02). The occurrence of Staphylococcus aureus SSI was significantly lower in the patients who had application of intrawound vancomycin (32% vs 65%, P = .003). None of the patients who had application of intrawound vancomycin powder, and subsequently developed an S aureus SSI, demonstrated pathogens with resistance to vancomycin. All patients had MIC < 2 μg/mL, the vancomycin susceptibility threshold. The occurrence of gram-negative SSI (28% vs 7%) and culture negative fluid collection (16% vs 5%) was higher in the vancomycin cohort.

CONCLUSIONS: The use of intrawound vancomycin during the index spine surgery was protective against SSI following spine surgery. The application of intrawound vancomycin during index surgery does not appear to create vancomycin-resistant organisms in the event of an SSI.

Complication Rates Associated With Adult Cervical Deformity Surgery


Neurosurgery 79:378–388, 2016

Few reports have focused on treatment of adult cervical deformity (ACD).

OBJECTIVE: To present early complication rates associated with ACD surgery.

METHODS: A prospective multicenter database of consecutive operative ACD patients was reviewed for early (#30 days from surgery) complications. Enrollment required at least 1 of the following: cervical kyphosis .10 degrees, cervical scoliosis .10 degrees, C2-7 sagittal vertical axis .4 cm, or chin-brow vertical angle .25 degrees.

RESULTS: Seventy-eight patients underwent surgical treatment for ACD (mean age, 60.8 years). Surgical approaches included anterior-only (14%), posterior-only (49%), anterior-posterior (35%), and posterior-anterior-posterior (3%). Mean numbers of fused anterior and posterior vertebral levels were 4.7 and 9.4, respectively. A total of 52 early complications were reported, including 26 minor and 26 major. Twenty-two (28.2%) patients had at least 1 minor complication, and 19 (24.4%) had at least 1 major complication. Overall, 34 (43.6%) patients had at least 1 complication. The most common complications included dysphagia (11.5%), deep wound infection (6.4%), new C5 motor deficit (6.4%), and respiratory failure (5.1%). One (1.3%) mortality occurred. Early complication rates differed significantly by surgical approach: anterior-only (27.3%), posterior-only (68.4%), and anterior-posterior/posterior-anterior- posterior (79.3%) (P = .007).

CONCLUSION: This report provides benchmark rates for overall and specific ACD surgery complications. Although the surgical approach(es) used were likely driven by the type and complexity of deformity, there were significantly higher complication rates associated with combined and posterior-only approaches compared with anterior-only approaches. These findings may prove useful in treatment planning, patient counseling, and ongoing efforts to improve safety of care.

High-dose proton-based radiation therapy in the management of spine chordomas


J Neurosurg Spine 23:788–797, 2015

Spinal chordomas can have high local recurrence rates after surgery with or without conventional dose radiation therapy (RT). Treatment outcomes and prognostic factors after high-dose proton-based RT with or without surgery were assessed.

Methods The authors conducted a retrospective review of 126 treated patients (127 lesions) categorized according to disease status (primary vs recurrent), resection (en bloc vs intralesional), margin status, and RT timing.

Results Seventy-one sacrococcygeal, 40 lumbar, and 16 thoracic chordomas were analyzed. Mean RT dose was 72.4 GyRBE (relative biological effectiveness). With median follow-up of 41 months, the 5-year overall survival (OS), local control (LC), locoregional control (LRC), and distant control (DC) for the entire cohort were 81%, 62%, 60%, and 77%, respectively. LC for primary chordoma was 68% versus 49% for recurrent lesions (p = 0.058). LC if treated with a component of preoperative RT was 72% versus 54% without this treatment (p = 0.113). Among primary tumors, LC and LRC were higher with preoperative RT, 85% (p = 0.019) and 79% (0.034), respectively, versus 56% and 56% if no preoperative RT was provided. Overall LC was significantly improved with en bloc versus intralesional resection (72% vs 55%, p = 0.016), as was LRC (70% vs 53%, p = 0.035). A trend was noted toward improved LC and LRC for R0/R1 margins and the absence of intralesional procedures.

Conclusions High-dose proton-based RT in the management of spinal chordomas can be effective treatment. In patients undergoing surgery, those with primary chordomas undergoing preoperative RT, en bloc resection, and postoperative RT boost have the highest rate of local tumor control; among 28 patients with primary chordomas who underwent preoperative RT and en bloc resection, no local recurrences were seen. Intralesional and incomplete resections are associated with higher local failure rates and are to be avoided.

Subsidence after lateral interbody fusion

Assessment and classi cation of subsidence after lateral interbody fusion using serial computed tomography

J Neurosurg Spine 23:589–597, 2015

Intervertebral cage settling during bone remodeling after lumbar lateral interbody fusion (LIF) is a common occurrence during the normal healing process. Progression of this settling with endplate collapse is defined as subsidence. The purposes of this study were to 1) assess the rate of subsidence after minimally invasive (MIS) LIF by CT, 2) distinguish between early cage subsidence (ECS) and delayed cage subsidence (DCS), 3) propose a descriptive method for classifying the types of subsidence, and 4) discuss techniques for mitigating the risk of subsidence after MIS LIF.

Methods A total of 128 consecutive patients (with 178 treated levels in total) underwent MIS LIF performed by a single surgeon. The subsidence was deemed to be ECS if it was evident on postoperative Day 2 CT images and was therefore the result of an intraoperative vertebral endplate injury and deemed DCS if it was detected on subsequent CT scans (≥ 6 months postoperatively). Endplate breaches were categorized as caudal (superior endplate) and/or cranial (inferior endplate), and as ipsilateral, contralateral, or bilateral with respect to the side of cage insertion. Subsidence seen in CT images (radiographic subsidence) was measured from the vertebral endplate to the caudal or cranial margin of the cage (in millimeters). Patient-reported outcome measures included visual analog scale, Oswestry Disability Index, and 36-Item Short Form Health Survey physical and mental component summary scores.

Results Four patients had ECS in a total of 4 levels. The radiographic subsidence (DCS) rates were 10% (13 of 128 patients) and 8% (14 of 178 levels), with 3% of patients (4 of 128) exhibiting clinical subsidence. In the DCS levels, 3 types of subsidence were evident on coronal and sagittal CT scans: Type 1, caudal contralateral, in 14% (2 of 14), Type 2, caudal bilateral with anterior cage tilt, in 64% (9 of 14), and Type 3, both endplates bilaterally, in 21% (3 of 14). The mean subsidence in the DCS levels was 3.2 mm. There was no significant difference between the numbers of patients in the subsidence (DCS) and no-subsidence groups who received clinical benefit from the surgical procedure, based on the minimum clinically important difference (p > 0.05). There was a significant difference between the fusion rates at 6 months (p = 0.0195); however, by 12 months, the difference was not significant (p = 0.2049).

Conclusions The authors distinguished between ECS and DCS. Radiographic subsidence (DCS) was categorized using descriptors for the location and severity of the subsidence. Neither interbody fusion rates nor clinical outcomes were affected by radiographic subsidence. To protect patients from subsidence after MIS LIF, the surgeon needs to take care with the caudal endplate during cage insertion. If a caudal bilateral (Type 2) endplate breach is detected, supplemental posterior fixation to arrest progression and facilitate fusion is recommended.

The Neurological Compromised Spine Due to Ewing Sarcoma. What First: Surgery or Chemotherapy?

The Neurological Compromised Spine Due to Ewing Sarcoma

Neurosurgery 77:718–725, 2015

The vertebral column is an infrequent site of primary involvement in Ewing sarcoma. Yet when Ewing sarcoma is found in the spine, the urge for decompression is high because of the often symptomatic compression of neural structures. It is unclear in alleviating a neurological deficit whether chemotherapy is preferred over decompressive laminectomy.

OBJECTIVE: To underline, in this case series, the efficiency of initial chemotherapy before upfront surgery in the setting of high-grade spinal cord or cauda equina compression of primary Ewing sarcoma.

METHODS: Fifteen patients with Ewing sarcoma primarily located in the spine were treated at our institution between 1983 and 2015. Localization, neurological deficit expressed as Frankel grade, and outcome expressed as Rankin scale before and after initial chemotherapy, the recurrence rate, and overall survival were evaluated. The multidisciplinary approach of 1 case will be discussed in detail.

RESULTS: Nine patients (60%) were female. The age at presentation was 15.0 ± 5.5 years (range: 0.9-22.8 years). Ten patients (67%) were initially treated with chemotherapy, and 1 patient (7%) was treated primarily with radiotherapy followed by chemotherapy. The remaining 4 patients (27%) were initially treated with decompressive surgery. All patients treated primarily nonsurgically improved neurologically at followup, showing the importance of chemotherapy as an effective initial treatment option.

CONCLUSION: Adequate and quick decompression of neural structures with similar results can be achieved by chemotherapy and radiotherapy, avoiding the local spill of malignant cells.

Three-Dimensional Computed Tomography-Based Spinal Navigation in Minimally Invasive Lateral Lumbar Interbody Fusion

Three-Dimensional Computed Tomography-Based Spinal Navigation in Minimally Invasive Lateral Lumbar Interbody Fusion4

Operative Neurosurgery 11:259–267, 2015

As with most minimally invasive spine procedures, lateral lumbar interbody fusion (LLIF) requires the use of biplanar fluoroscopy for localization and safe interbody cage placement. Computed tomography (CT)-based intraoperative spinal navigation has been shown to be more effective than fluoroscopic guidance for posterior-based approaches such as pedicle screw instrumentation. However, the use of spinal navigation in LLIF has not been well studied.

OBJECTIVE: To present the technique for using an intraoperative cone-beam CT and image-guided navigation system in LLIF and to provide a preliminary analysis of outcomes.

METHODS: We retrospectively analyzed a prospectively acquired database and the electronic records of patients undergoing LLIF with spinal navigation. Eight patients were identified. Postoperative neurological deficits were recorded. All patients underwent postprocedural CT and x-ray imaging for analysis of accuracy of cage placement. Accuracy of cage placement was determined by location within the disk space.

RESULTS: The mean age was 66 years, and 6 patients were women. A mean 2.8 levels were treated with a total of 22 lateral cages implanted via navigation. All cages were placed within quarters 1 to 2 or 2 to 3, signifying the anterior half or middle portions of the disk space. There were no sensory or motor deficits postoperatively.

CONCLUSION: Use of an intraoperative cone-beam CT with an image-guided navigation system is feasible and safe and appears to be accurate, although a larger study is required to confirm these results.

Atlantoaxial instability in acute odontoid fractures is associated with nonunion and mortality


The Spine Journal 15 (2015) 910–917

Odontoid fractures are the most common geriatric cervical spine fractures. Nonunion rates have been reported to be up to 40% and mortality up to 35%, and poor functional outcomes are common. Atlantoaxial instability (AAI) is a plausible prognostic factor, but its role has not been previously examined.

PURPOSE: To determine the effect of severe AAI on the outcomes of nonunion and mortality in patients with acute odontoid fractures.

STUDY DESIGN: Retrospective cohort/single institution.

PATIENT SAMPLE: One hundred twenty-four consecutive patients with acute odontoid fractures.

OUTCOME MEASURES: Rates of nonunion and mortality.

METHODS: Two independent blinded reviewers measured AAI using postinjury computed tomography scans. Patients were classified as having ‘‘severe’’ or ‘‘minimal’’ AAI on the basis of greater versus less than or equal to 50% mean subluxation across each C1–C2 facet joint. Rates of nonunion and mortality were compared using independent samples t tests and adjusted for age, displacement, and subtype using binary logistic regression.

RESULTS: One hundred seven patients had minimal AAI and 17 had severe AAI. Mean follow-up was 4.4 months (standard deviation54.6). Patients with severe AAI were more likely to experience nonunion (29% vs. 10%, respectively; p5.03) and mortality (35% vs. 14%, respectively; p5.03) regardless of treatment modality. Fracture displacement correlated with AAI (r250.65). When adjusted for patient age, the odds ratio of nonunion with severe AAI approached significance at 3.3 (95% confidence interval [CI]: 0.9–11.7). Mortality prediction with AAI approached a twofold increased risk (odds ratio52.1; 95% CI: 0.6–6.8). In patients with Type-II fractures, the odds of mortality with severe AAI approached a threefold higher risk (odds ratio53.3; 95% CI: 0.9–12.3).

CONCLUSIONS: Patients with acute odontoid fractures and severe AAI may be more likely to experience nonunion and mortality, suggesting the possibility that aggressive management could be warranted. Further investigation with a large prospective study including patient-important functional outcomes is justified. 

Minimally invasive lateral fusion for adjacent disease

Minimally invasive lateral interbody fusion for the treatment of rostral adjacent-segment lumbar degenerative stenosis without supplemental pedicle screw fixation

J Neurosurg Spine 21:861–866, 2014

Adjacent-segment degeneration and stenosis are common in patients who have undergone previous lumbar fusion. Treatment typically involves a revision posterior approach, which requires management of postoperative scar tissue and previously implanted instrumentation. A minimally invasive lateral approach allows the surgeon to potentially reduce the risk of these hazards. The technique relies on indirect decompression to treat central and foraminal stenosis and placement of a graft with a large surface area to promote robust fusion and stability in concert with the surrounding tensioned ligaments. The goal in this study was to determine if lateral interbody fusion without supplemental pedicle screws is effective in treating adjacent-segment disease.

Methods. For a 30-month study period at two institutions, the authors obtained all cases of lumbar fusion with new back and leg pain due to adjacent-segment stenosis and spondylosis failing conservative measures. All patients had undergone minimally invasive lateral interbody fusion from the side of greater leg pain without supplemental pedicle screw fixation. Patients were excluded from the study if they had undergone surgery for a nondegenerative etiology such as infection or trauma. They were also excluded if the intervention involved supplemental posterior instrumented fusion with transpedicular screws. Postoperative metrics included numeric pain scale (NPS) scores for leg and back pain. All patients underwent dynamic radiographs and CT scanning to assess stability and fusion after surgery.

Results. During the 30-month study period, 21 patients (43% female) were successfully treated using minimally invasive lateral interbody fusion without the need for subsequent posterior transpedicular fixation. The mean patient age was 61 years (range 37–87 years). Four patients had two adjacent levels fused, while the remainder had single-level surgery. All patients underwent surgery without conversion to a traditional open technique, and recombinant human bone morphogenetic protein–2 was used in the interbody space in all cases. The mean follow-up was 23.6 months. The mean operative time was 86 minutes, and the mean blood loss was 93 ml. There were no major intraoperative complications, but one patient underwent subsequent direct decompression in a delayed fashion. The leg pain NPS score improved from a mean of 6.3 to 1.9 (p < 0.01), and the back pain NPS score improved from a mean of 7.5 to 2.9 (p < 0.01). Intervertebral settling averaged 1.7 mm. All patients had bridging bone on CT scanning at the last follow-up, indicating solid bony fusion.

Conclusions. Adjacent-segment stenosis and spondylosis can be treated with a number of different operative techniques. Lateral interbody fusion provides an attractive alternative with reduced blood loss and complications, as there is no need to re-explore a previous laminectomy site. In this limited series a minimally invasive lateral approach provided high fusion rates when performed with osteobiological adjuvants.

Aneurysmal bone cysts of the spine: treatment options and considerations


J Neurooncol (2014) 120:171–178

Aneurysmal bone cysts (ABCs) are benign bone lesions with annual incidences ranging from 1.4 to 3.2 cases per million people. Approximately, 10–30 % of ABCs are found in the spine. Such lesions are traditionally treated with curettage or other intralesional techniques.

Because ABCs can be locally aggressive, intralesional resection can be incomplete and result in recurrence. This has led to increased use of novel techniques, including selective arterial embolization (SAE).

This study aims to: (1) compare outcomes based on extent of surgical resection, and (2) compare the efficacy of SAE versus surgical resection.

Clinical data pertaining to 71 cases of spinal ABCs were ambispectively collected from nine institutions in Europe, North America, and Australia. Twenty-two spinal ABCs were treated with surgery, 32 received preoperative embolization and surgery, and 17 were treated with SAE.

Most tumors were classified as Enneking stage 2 (n = 29, 41 %) and stage 3 (n = 29, 41 %). Local recurrence and survival were investigated and a significant difference was not observed between treatment groups. However, all three local recurrences occurred following surgical resection. Surgical resection was further categorized based on Enneking appropriateness. Recurrences only occurred following intralesional Enneking inappropriate (EI) resections (P = 0.10), a classification that characterized 47 % of all surgical resections. Furthermore, 56 % of intralesional resections were EI, compared to only 10 % of en bloc resections (P = 0.01). Although SAE treatment did not result in any local recurrences, 35 % involved more than five embolization procedures.

Spinal ABCs can be effectively treated with intralesional resection, en bloc resection, or SAE. Preoperative embolization should be considered before intralesional resection to limit intraoperative bleeding. Treatment plans must be guided by lesion characteristics and clinical presentation.

Surgical treatment of pathological loss of lumbar lordosis (flatback)


J Neurosurg Spine 21:160–170, 2014

Increased sagittal vertical axis (SVA) correlates strongly with pain and disability for adults with spinal deformity. A subset of patients with sagittal spinopelvic malalignment (SSM) have flatback deformity (pelvic incidence–lumbar lordosis [PI-LL] mismatch > 10°) but remain sagittally compensated with normal SVA. Few data exist for SSM patients with flatback deformity and normal SVA. The authors’ objective was to compare baseline disability and treatment outcomes for patients with compensated (SVA < 5 cm and PI-LL mismatch > 10°) and decompensated (SVA > 5 cm) SSM.

Methods. The study was a multicenter, prospective analysis of adults with spinal deformity who consecutively underwent surgical treatment for SSM. Inclusion criteria included age older than 18 years, presence of adult spinal deformity with SSM, plan for surgical treatment, and minimum 1-year follow-up data. Patients with SSM were divided into 2 groups: those with compensated SSM (SVA < 5 cm and PI-LL mismatch > 10°) and those with decompensated SSM (SVA ≥ 5 cm). Baseline and 1-year follow-up radiographic and health-related quality of life (HRQOL) outcomes included Oswestry Disability Index, Short Form–36 scores, and Scoliosis Research Society–22 scores. Percentages of patients achieving minimal clinically important difference (MCID) were also assessed.

Results. A total of 125 patients (27 compensated and 98 decompensated) met inclusion criteria. Compared with patients in the compensated group, patients in the decompensated group were older (62.9 vs 55.1 years; p = 0.004) and had less scoliosis (43° vs 54°; p = 0.002), greater SVA (12.0 cm vs 1.7 cm; p < 0.001), greater PI-LL mismatch (26° vs 20°; p = 0.013), and poorer HRQOL scores (Oswestry Disability Index, Short Form-36 physical component score, Scoliosis Research Society-22 total; p ≤ 0.016). Although these baseline HRQOL differences between the groups reached statistical significance, only the mean difference in Short Form–36 physical component score reached threshold for MCID. Compared with baseline assessment, at 1 year after surgery improvement was noted for patients in both groups for mean SVA (compensated –1.1 cm, decompensated +4.8 cm; p ≤ 0.009), mean PI-LL mismatch (compensated 6°, decompensated 5°; p < 0.001), and all HRQOL measures assessed (p ≤ 0.005). No significant differences were found between the compensated and decompensated groups in the magnitude of HRQOL score improvement or in the percentages of patients achieving MCID for each of the outcome measures assessed.

Conclusions. Decompensated SSM patients with elevated SVA experience significant disability; however, the amount of disability in compensated SSM patients with flatback deformity caused by PI-LL mismatch but normal SVA is underappreciated. Surgical correction of SSM demonstrated similar radiographic and HRQOL score improvements for patients in both groups. Evaluation of SSM should extend beyond measuring SVA. Among patients with concordant pain and disability, PI-LL mismatch must be evaluated for SSM patients and can be considered a primary indication for surgery.

Minimally invasive spine surgery in the treatment of thoracolumbar and lumbar spine trauma

Minimally invasive spine surgery in the treatment of thoracolumbar and lumbar spine trauma

Neurosurg Focus 37 (1):E11, 2014

Thoracolumbar and lumbar trauma account for the majority of traumatic spinal injuries. The mainstay of current treatments is still nonoperative therapy with bracing. Classic treatment algorithms reserved absolute surgical intervention for spinal trauma patients with neurological compromise or instability. Relative indications included incapacitating pain and obesity/body habitus making brace therapy ineffective.

In the past decade, minimally invasive surgical (MIS) techniques for spine surgery have been increasingly used for degenerative conditions. These same minimally invasive techniques have seen increased use in trauma patients. The goal of minimally invasive surgery is to decrease surgical morbidity through decreased soft-tissue dissection while providing the same structural stability afforded by classic open techniques.

These minimally invasive techniques involve percutaneous posterior pedicle fixation, vertebral body augmentation, and utilization of endoscopic and thoracoscopic techniques.

While MIS techniques are somewhat in their infancy, an increasing number of studies are reporting good clinical and radiographic outcomes with these MIS techniques. However, the literature is still lacking high-quality evidence comparing these newer techniques to classic open treatments. This article reviews the relevant literature regarding minimally invasive spine surgery in the treatment of thoracolumbar and lumbar trauma.

Cost-effectiveness analysis in minimally invasive spine surgery

Cost-effectiveness analysis in MISS

Neurosurg Focus 36 (6):E4, 2014

Medical care has been evolving with the increased influence of a value-based health care system. As a result, more emphasis is being placed on ensuring cost-effectiveness and utility in the services provided to patients. This study looks at this development in respect to minimally invasive spine surgery (MISS) costs.

Methods. A literature review using PubMed, the Cost-Effectiveness Analysis (CEA) Registry, and the National Health Service Economic Evaluation Database (NHS EED) was performed. Papers were included in the study if they reported costs associated with minimally invasive spine surgery (MISS). If there was no mention of cost, CEA, cost-utility analysis (CUA), quality-adjusted life year (QALY), quality, or outcomes mentioned, then the article was excluded.

Results. Fourteen studies reporting costs associated with MISS in 12,425 patients (3675 undergoing minimally invasive procedures and 8750 undergoing open procedures) were identified through PubMed, the CEA Registry, and NHS EED. The percent cost difference between minimally invasive and open approaches ranged from 2.54% to 33.68%—all indicating cost saving with a minimally invasive surgical approach. Average length of stay (LOS) for minimally invasive surgery ranged from 0.93 days to 5.1 days compared with 1.53 days to 12 days for an open approach. All studies reporting EBL reported lower volume loss in an MISS approach (range 10–392.5 ml) than in an open approach (range 55–535.5 ml).

Conclusions. There are currently an insufficient number of studies published reporting the costs of MISS. Of the studies published, none have followed a standardized method of reporting and analyzing cost data. Preliminary findings analyzing the 14 studies showed both cost saving and better outcomes in MISS compared with an open approach. However, more Level I CEA/CUA studies including cost/QALY evaluations with specifics of the techniques utilized need to be reported in a standardized manner to make more accurate conclusions on the cost effectiveness of minimally invasive spine surgery.

Traumatic injuries to the craniovertebral junction: a review of rare events

Traumatic injuries CVJ

Neurosurg Rev (2014) 37:203–216

The craniovertebral junction is a specific region of the spine with unique anatomical and biomechanical properties that yields a wide variety of injury patterns.

Junctional traumatic fractures and/or dislocations are widely reported in clinical practice, but we could identify only a subgroup of upper cervical spine traumatic injuries with very few cases reported in the literature, and for this reason may be considered rare.

In some of these cases, the absence of spinal biomechanical instability, in association with moderate clinical symptoms (neck stiffness and pain) and the difficulty in fracture identification through standard cervical radiographs, leads to a high percentage of missed injuries.

In other cases, traumatic events have been commonly described only in autopsy series due to the high degree of spinal biomechanical instability.

Herein, we have summarized all the relevant literature concerning this issue and also included our cases, with the aim of emphasizing prompt diagnosis and correct management.

We provide a guide for correctly identifying “rare” craniovertebral junction traumatic injuries.

A standardized nomenclature for cervical spine soft-tissue release and osteotomy for deformity correction

Standardized nomenclature cervical osteotomies

J Neurosurg Spine 19:269–278, 2013

Cervical spine osteotomies are powerful techniques to correct rigid cervical spine deformity. Many variations exist, however, and there is no current standardized system with which to describe and classify cervical osteotomies. This complicates the ability to compare outcomes across procedures and studies. The authors’ objective was to establish a universal nomenclature for cervical spine osteotomies to provide a common language among spine surgeons.


A proposed nomenclature with 7 anatomical grades of increasing extent of bone/soft tissue resection and destabilization was designed. The highest grade of resection is termed the major osteotomy, and an approach modifier is used to denote the surgical approach(es), including anterior (A), posterior (P), anterior-posterior (AP), posterior-anterior (PA), anterior-posterior-anterior (APA), and posterior-anterior-posterior (PAP). For cases in which multiple grades of osteotomies were performed, the highest grade is termed the major osteotomy, and lower-grade osteotomies are termed minor osteotomies. The nomenclature was evaluated by 11 reviewers through 25 different radiographic clinical cases. The review was performed twice, separated by a minimum 1-week interval. Reliability was assessed using Fleiss kappa coefficients.


The average intrarater reliability was classified as “almost perfect agreement” for the major osteotomy (0.89 [range 0.60–1.00]) and approach modifier (0.99 [0.95–1.00]); it was classified as “moderate agreement” for the minor osteotomy (0.73 [range 0.41–1.00]). The average interrater reliability for the 2 readings was the following: major osteotomy, 0.87 (“almost perfect agreement”); approach modifier, 0.99 (“almost perfect agreement”); and minor osteotomy, 0.55 (“moderate agreement”). Analysis of only major osteotomy plus approach modifier yielded a classification that was “almost perfect” with an average intrarater reliability of 0.90 (0.63–1.00) and an interrater reliability of 0.88 and 0.86 for the two reviews.


The proposed cervical spine osteotomy nomenclature provides the surgeon with a simple, standard description of the various cervical osteotomies. The reliability analysis demonstrated that this system is consistent and directly applicable. Future work will evaluate the relationship between this system and health-related quality of life metrics.

Pathology of Spinal Ependymomas

Pathology of Spinal Ependymomas

Neurosurgery 73:247–255, 2013

Ependymomas constitute approximately 40% of primary intraspinal tumors. Current World Health Organization (WHO) grading may not correlate with observed progression-free survival (PFS).

OBJECTIVE: This retrospective study of prospectively collected data examines whether PFS is influenced by the histological grade or by the extent of resection. It also analyzes the usage and effectiveness of postoperative adjuvant radiotherapy.

METHODS: We reviewed 134 consecutive patients with ependymomas of all grades. Pathology slides were re-reviewed and the histological grades were confirmed by a single neuropathologist. Postoperative residual or recurrence was evaluated with follow-up magnetic resonance imaging.

RESULTS: There were 85 male and 49 female patients, ranging from 10 to 79 (median 41) years of age. Thirty patients had WHO grade I tumors, 101 had grade II tumors, and 3 had grade III tumors. Kaplan-Meier analysis of PFS demonstrated a mean duration of 6 years for grade I, 14.9 years for grade II, and 3.7 years for grade III (P , .001). In grade II ependymomas, mean PFS was 11.2 years with subtotal resection and 17.8 years with gross total resection (P, .01). PFS of patients who underwent subtotal resection was not significantly changed by adjuvant radiotherapy (P , .36).

CONCLUSION: Patients with grade II ependymoma have significantly longer PFS than patients with grade I ependymoma. The extent of resection did not affect PFS in grade I ependymoma but it did in grade II. Contrary to its higher grade, WHO grade II ependymoma carries a better prognosis than WHO grade I ependymoma.

Axial Spondylectomy and Circumferential Reconstruction via a Posterior Approach

Axial spondylectomy

Neurosurgery 72:300–309, 2013

Spinal metastases of the second cervical vertebra are a subset of tumors that are particularly difficult to address surgically. Previously described techniques require highly morbid circumferential dissection posterior to the pharynx for resection and reconstruction.

OBJECTIVE: To perform a biomechanical analysis of instrumented reconstruction configurations used after axial spondylectomy and to demonstrate safe use of a novel construct in a patient case report.

METHODS: Several different published and novel reconstruction configurations were inserted into 7 occipitocervical spines that underwent axial spondylectomy. A biomechanical analysis of the stiffness of the constructs in flexion and extension, lateral bending, and rotation was performed. A patient then underwent a posterior-only approach for axial spondylectomy and circumferential reconstruction.

RESULTS: Biomechanical analysis of different constructs demonstrated that anterior column reconstruction with bilateral cages spanning the C1 lateral mass to the C3 facet in combination with occipitocervical instrumentation was superior in flexion-extension and equivalent in lateral bending and rotation to currently used constructs. The patient in whom this construct was placed via a posterior-only approach for axial spondylectomy and instrumentation remained at neurological baseline and demonstrated no recurrence of local disease or failure of instrumentation to date.

CONCLUSION: When C1 lateral mass to C3 facet bilateral cage plus occipitocervical instrumentation is compared with existing anterior and posterior constructs, this novel reconstruction is biomechanically equivalent if not superior in performance. In a patient, the posterior-only approach for C2 spondylectomy with the novel reconstruction was safe and durable and avoided the morbidity of the anterior approach.

Combined “Hybrid” Open and Minimally Invasive Surgical Correction of Adult Thoracolumbar Scoliosis: A Retrospective Cohort Study


Neurosurgery 72:151–159, 2013

Surgery for scoliosis requires extensive exposure, resulting in significant tissue injury and longer recovery times. To minimize morbidity in scoliosis surgery, several studies have shown successful application of a combination of minimally invasive techniques; however, the extent of scoliosis treated has been modest.

OBJECTIVE: To achieve some of the benefits of minimally invasive surgery and yet treat curves of greater degree, we have used a combined approach, incorporating both open and minimally invasive techniques.

METHODS: We analyzed a prospectively acquired database in addition to reviewing electronic records of patients undergoing hybrid surgery for thoracolumbar scoliosis. Nine patients were identified. The minimally invasive portion involved the lumbar region in all cases. Pain was assessed by the visual analog scale and disability was measured by the Oswestry Disability Index.

RESULTS: Mean preoperative scoliosis was 47.8 degrees, which was corrected to a mean 15.2 degrees. An average of 7.8 spinal levels was treated. Estimated blood loss averaged 1094.4 mL, and length of hospital stay averaged 7.2 days. Acute complications occurred in 2 patients. Longer term complications occurred in 2 patients, consisting of adjacent segment disease. The mean improvement in the visual analog scale score was 3.7 and the mean improvement on the Oswestry Disability Index was 30.5. Average follow-up was 29.2 months.

CONCLUSION: The hybrid approach for the treatment of scoliosis results in acceptable radiographic and clinical outcomes. Complications did not appear increased compared with those expected with scoliosis surgery. Although decreased adjacent tissue injury was achieved with the minimally invasive component of the procedure, a larger comparative study is required to determine magnitude of this benefit.

Incidental durotomy after spinal surgery: a prospective study in an academic institution

J Neurosurg Spine 17:30–36, 2012

Incidental durotomies (IDs) are an unfortunate but anticipated potential complication of spinal surgery. The authors surveyed the frequency of IDs for a single spine surgeon and analyzed the major risk factors as well as the impact on long-term patient outcomes.

Methods. The authors conducted a prospective review of elective spinal surgeries performed over a 15-year period. Any surgery involving peripheral nerve only, intradural procedures, or dural tears due to trauma were excluded from analysis. The incidence of ID was categorized by surgery type including primary surgery, revision surgery, and so forth. Incidence of ID was also examined in the context of years of physician experience and training. Furthermore, the incidence and types of sequelae were examined in patients with an ID.

Results. Among 3000 elective spinal surgery cases, 3.5% (104) had an ID. The incidence of ID during minimally invasive procedures (3.3%) was similar, but no patients experienced long-term sequelae. The incidence of ID during revision surgery (6.5%) was higher. There was a marked difference in incidence between cervical (1.3%) and thoracolumbar (5.1%) cases. The incidence was lower for cases involving instrumentation (2.4%). When physician training was examined, residents were responsible for 49% of all IDs, whereas fellows were responsible for 26% and the attending for 25%. Among all of the cases that involved an ID, 7.7% of patients went on to experience a neurological deficit as compared with 1.5% of those without an ID. The overall failure rate of dural repair was 6.9%, and failure was almost 3 times higher (13%) in revision surgery as compared with a primary procedure (5%).

Conclusions. The authors established a reliable baseline incidence for durotomy after spine surgery: 3.5%. They also identified risk factors that can increase the likelihood of a durotomy, including location of the spinal procedure, type of procedure performed, and the implementation of a new procedure. The years of physician training or resident experience did not appear to be a major risk for ID.

Role of Cancer Stem Cells in Spine Tumors

Neurosurgery 71:117–125, 2012 DOI: 10.1227/NEU.0b013e3182532e71

The management of spinal column tumors continues to be a challenge for clinicians. The mechanisms of tumor recurrence after surgical intervention as well as resistance to radiation and chemotherapy continue to be elucidated. Furthermore, the pathophysiology of metastatic spread remains an area of active investigation.

There is a growing body of evidence pointing to the existence of a subset of tumor cells with high tumorigenic potential in many spine cancers that exhibit characteristics similar to those of stem cells. The ability to self-renew and differentiate into multiple lineages is the hallmark of stem cells, and tumor cells that exhibit these characteristics have been described as cancer stem cells (CSCs).

The mechanisms that allow nonmalignant stem cells to promote normal developmental programming by way of enhanced proliferation, promotion of angiogenesis, and increased motility may be used by CSCs to fuel carcinogenesis.

The purpose of this review is to discuss what is known about the role of CSCs in tumors of the osseous spine. First, this article reviews the fundamental concepts critical to understanding the role of CSCs with respect to chemoresistance, radioresistance, and metastatic disease. This discussion is followed by a review of what is known about the role of CSCs in the most common primary tumors of the osseous spine.

Neurosurgery Department. “La Fe” University Hospital. Valencia, Spain


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