Category: Spine

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Extension CT scan: its suitability for assessing fusion after posterior lumbar interbody fusion

Eur Spine J (2011) 20:1496–1502. DOI 10.1007/s00586-011-1739-0

Posterior lumbar interbody fusion (PLIF) is a popular procedure for treating lumbar canal stenosis with spinal instability, and several reports concerning fusion assessment methods exist. However, there are currently no definitive criteria for diagnosing a successful interbody fusion in the lumbar spine. We suggested evaluating fusion status using computed tomography (CT) in extension position to detect pseudoarthrosis more precisely.

The purpose of this study was to evaluate its usefulness for determining bone union quality after PLIF.

Eighty-one patients who underwent PLIF at 97 levels were retrospectively enrolled. The study population included 48 men and 33 women (mean age 58.9 years, range 21–85 years). Patients were followed up for more than 12 months after surgery. The mean follow-up period was 27.6 months (range 14–49 months). Fusion status was evaluated using three ways: flexion– extension radiographs, CT images in flexion and extension position. In the flexion–extension radiographs, mobility of more than 3 , a remaining clear zone, or an uncertain bone connection constituted an incomplete union. For CT images, a remaining clear zone, a gas pattern, or an uncertain bone connection constituted an incomplete union.

Flexion– extension radiographs demonstrated a solid fusion in 90.7% of the 97 levels at 10.7 months postoperatively. When fusion was demonstrated on flexion–extension radiographs, the rate of fusion affirmed by flexion CT and extension CT was 87.6 and 69.1% of the levels assessed, respectively. The rate of pseudoarthrosis detected on extension CT images was significantly higher than that on flexion–extension radiographs (P< 0.001) and flexion CT (P< 0.01). The rate of fusion achieved on extension CT was 85.6% at 15.1 months postoperatively.

Extension CT could detect pseudoarthrosis more clearly than flexion–extension radiography and flexion CT. The CT images are influenced by body position and dilating anterior disc space in extension CT contributes to detect pseudoarthrodesis. Thus, extension CT was a useful method for assessing fusion status after PLIF.

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Acidic fibroblast growth factor for repair of human spinal cord injury: a clinical trial

J Neurosurg Spine 15:216–227, 2011. DOI: 10.3171/2011.4.SPINE10404

The study aimed to verify the safety and feasibility of applying acidic fibroblast growth factor (aFGF) with fibrin glue in combination with surgical neurolysis for nonacute spinal cord injury.

Methods. This open-label, prospective, uncontrolled human clinical trial recruited 60 patients with spinal cord injuries (30 cervical and 30 thoracolumbar). The mean patient age was 36.5 ± 15.33 (mean ± SD) years, and the male/ female ratio was 3:1. The mean time from injury to treatment was 25.7 ± 26.58 months, and the cause of injury included motor vehicle accident (26 patients [43.3%]), fall from a height (17 patients [28.3%]), sports (4 patients [6.7%]), and other (13 patients [21.7%]). Application of aFGF with fibrin glue and duraplasty was performed via laminectomy, and an adjuvant booster of combined aFGF and fibrin glue (2 ml) was given at 3 and 6 months postsurgery via lumbar puncture. Outcome measurements included the American Spinal Injury Association (ASIA) motor scores, sensory scores, impairment scales, and neurological levels. Examination of functional independence measures, visual analog scale, MR imaging, electrophysiological and urodynamic studies, hematology and biochemistry tests, tumor markers, and serum inflammatory cytokines were all conducted. All adverse events were monitored and reported. Exclusions were based on refusal, unrelated adverse events, or failure to participate in the planned rehabilitation.

Results. Forty-nine patients (26 with cervical and 23 with thoracolumbar injuries) completed the 24-month trial. Compared with preoperative conditions, the 24-month postoperative ASIA motor scores improved significantly in the cervical group (from 27.6 ± 15.55 to 37.0 ± 19.93, p < 0.001) and thoracolumbar group (from 56.8 ± 9.21 to 60.7 ± 10.10, p < 0.001). The ASIA sensory scores also demonstrated significant improvement in light touch and pinprick in both groups: from 55.8 ± 24.89 to 59.8 ± 26.47 (p = 0.049) and 56.3 ± 23.36 to 62.3 ± 24.87 (p = 0.003), respectively, in the cervical group and from 75.7 ± 15.65 to 79.2 ± 15.81 (p < 0.001) and 78.2 ± 14.72 to 82.7 ± 16.60 (p < 0.001), respectively, in the thoracolumbar group. At 24-month follow-up, the ASIA impairment scale improved significantly in both groups (30% cervical [p = 0.011] and 30% thoracolumbar [p = 0.003]). There was also significant improvement in neurological level in the cervical (from 5.17 ± 1.60 to 6.27 ± 3.27, p = 0.022) and thoracolumbar (from 18.03 ± 4.19 to 18.67 ± 3.96, p = 0.001) groups. The average sum of motor items in functional independence measure also had significant improvement in both groups (p < 0.05). The walking/wheelchair locomotion subscale showed increased percentages of patients who were ambulatory (from 3.4% to 13.8% and from 17.9% to 35.7% in the cervical and thoracolumbar groups, respectively). There were no related adverse events.

Conclusions. The use of aFGF for spinal cord injury was safe and feasible in the present trial. There were significant improvements in ASIA motor and sensory scale scores, ASIA impairment scales, neurological levels, and functional independence measure at 24 months after treatment. Further large-scale, randomized, and controlled investigations are warranted to evaluate the efficacy and long-term results.

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Meta-analysis of instrumented posterior interbody fusion versus instrumented posterolateral fusion in the lumbar spine

J Neurosurg Spine 15:295–310, 2011.DOI: 10.3171/2011.4.SPINE10330

The authors compared the effectiveness of instrumented posterior lumbar interbody fusion (iPLIF) and instrumented posterolateral fusion (iPLF) for the treatment of low-back pain (LBP) due to degenerative lumbar disease.

Methods. Relevant randomized controlled trials (RCTs) and comparative observational studies through December 2009 were identified using a retrieval strategy of sensitive and specific searches. The study design, participant characteristics, interventions, follow-up rate and period, and outcomes were abstracted after the assessment of methodological quality of the trials. Analyses were performed following the method guidelines of the Cochrane Back Review Group.
Results. Nine studies were identified—3 RCTs and 6 comparative observational studies. No significant difference was found between the 2 fusion procedures in the global assessment of clinical outcome (OR 1.51, 95% CI 0.71–3.22, p = 0.29) and complication rate (OR 0.55, 95% CI 0.16–1.86, p = 0.34). Both techniques were effective in reducing pain and improving functional disability, as well as restoring intervertebral disc height. Instrumented PLIF was more effective in achieving solid fusion (OR 2.60, 95% CI 1.35–5.00, p = 0.004), a lower reoperation rate (OR 0.20, 95% CI 0.03–1.29, p = 0.09), and better restoration of segmental angle and lumbar lordotic angle than iPLF. There were no significant differences between the fusion methods regarding blood loss (weighted mean difference –179.63, 95% CI –516.42 to 157.15, p = 0.30), and operating time (weighted mean difference 8.03, 95% CI –45.46 to 61.53, p = 0.77).

Conclusions. The authors’ analysis provided moderate-quality evidence that iPLIF has the advantages of higher fusion rate and better restoration of spinal alignment over iPLF. No significant differences were identified between iPLIF and iPLF concerning clinical outcome, complication rate, operating time, and blood loss.

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Nonfusion stabilization of the degenerative lumbar spine

J Neurosurg Spine 15:151–158, 2011. DOI: 10.3171/2011.3.SPINE0969

The goal of this study was to assess whether a stable but nonrigid nonfusion implant can stabilize the spine in degenerative diseases and also prevent instability following decompression. Instrumented spondylodesis is a recognized surgical treatment in degenerative disease of the lumbar spine. However, pain can develop at the bone graft donor site and the operative trauma can be very stressful in elderly patients, and it is suspected that there may be increased degenerative changes in the adjacent segments. In 2002, a nonrigid but rotationally stable pedicle screw and rod system was introduced, which could be used without additional fusion (referred to hereafter as the Cosmic system).

Methods. A total of 139 patients with degenerative disease of the lumbar spine underwent spinal stabilization with the Cosmic system without additional spondylodesis. Seventy patients had an additional decompression. The minimum follow-up was 2 years. The perioperative course, the clinical results, and the erect anteroposterior and lateral radiographs were recorded and compared with the preoperative data. The data were obtained from 6 different spine centers in Europe and documented on an Internet platform.

Results. The Oswestry Disability Index score improved from 48.9% to 22.5%, and the visual analog scale score decreased from 7.3 to 2.5. Lumbar lordosis did not change, nor did the adjacent disc height. Eleven patients underwent revision, 4 of them for implant failure. Of the 139 patients, 110 assessed the result as excellent, very good, or good; 24 as fair; and 5 as poor. A total of 122 patients would undergo surgery again. There were no significant differences between patients with or without an additional decompression.

Conclusions. The Cosmic system is a stable but nonrigid posterior nonfusion system. Implant complications are low and the clinical outcome is good. Longer follow-up is necessary to confirm the 2-year results.

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Cost-effectiveness of transforaminal lumbar interbody fusion for Grade I degenerative spondylolisthesis

J Neurosurg Spine 15:138–143, 2011. DOI: 10.3171/2011.3.SPINE10562

Transforaminal lumbar interbody fusion (TLIF) for spondylolisthesis-associated back and leg pain is associated with improvement in pain, disability, and quality of life. However, given the rising health care costs associated with spinal fusion procedures and varying results of recent cost-utility studies, the cost-effectiveness of TLIF remains unclear. The authors set out to assess the comprehensive costs of TLIF at their institution and to determine its cost-effectiveness in the treatment of degenerative spondylolisthesis.

Methods. Forty-five patients undergoing TLIF for Grade I degenerative spondylolisthesis–associated back and leg pain after 6–12 months of conservative therapy were included. The authors assessed the 2-year back pain visual analog scale (VAS) score, leg pain VAS score, Oswestry Disability Index, and total back-related medical resource utilization, missed work, and health-state values (quality-adjusted life years [QALYs], calculated from EQ-5D with US valuation). Two-year resource use was multiplied by unit costs based on Medicare national allowable payment amounts (direct cost), and patient and caregiver workday losses were multiplied by the self-reported gross-of-tax wage rate (indirect cost). The mean total 2-year cost per QALY gained after TLIF was assessed.

Results. Compared with preoperative health states reported after at least 6 months of medical management, a significant improvement in back pain VAS score, leg pain VAS score, and Oswestry Disability Index was observed 2 years after TLIF, with a mean 2-year gain of 0.86 QALYs. The mean ± SD total 2-year cost of TLIF was $36,836 ± $11,800 (surgery cost, $21,311 ± $2800; outpatient resource utilization cost, $3940 ± $2720; indirect cost, $11,584 ± $11,363). Transforaminal lumbar interbody fusion was associated with a mean 2-year cost per QALY gained of $42,854.

Conclusions. Transforaminal lumbar interbody fusion improved pain, disability, and quality of life in patients with degenerative spondylolisthesis–associated back and leg pain. The total cost per QALY gained for TLIF was $42,854 when evaluated 2 years after surgery with Medicare fees, suggesting that TLIF is a cost-effective treatment of lumbar spondylolisthesis.

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Ability of electromyographic monitoring to determine the presence of malpositioned pedicle screws in the lumbosacral spine: analysis of 2450 consecutively placed screws

J Neurosurg Spine 15:130–135, 2011.DOI: 10.3171/2011.3.SPINE101

Pedicle screws provide efficient stabilization along all 3 columns of the spine, but they can be technically demanding to place, with malposition rates ranging from 5% to 10%. Intraoperative electromyographic (EMG) monitoring has the capacity to objectively identify a screw breaching the medial pedicle cortex that is in proximity to a nerve root. The purpose of this study is to describe and evaluate the authors’ 7-year institutional experience with intraoperative EMG monitoring during placement of lumbar pedicle screws and to determine the clinical utility of intraoperative EMG monitoring.

Methods. The authors retrospectively studied 2450 consecutive lumbar pedicle screws placed in 418 patients from June 2002 through June 2009. All screws were inserted using a free-hand technique and anatomical landmarks, stimulated at 10.0 mA, and evaluated with CT scanning within 48 hours postoperatively. Medial pedicle screw breach was defined as having greater than 25% of the screw diameter extend outside of the pedicle, as confirmed on CT scanning or intraoperatively by a positive EMG response indicating a medial breach. The sensitivity and specificity of intraoperative EMG monitoring in detecting the presence of a medial screw breach was evaluated based on the following definitions: 1) true positive (a positive response to EMG stimulation confirmed as a breach intraoperatively or on postoperative CT scans); 2) false positive (positive response to EMG stimulation confirmed as a correctly positioned screw on postoperative CT scans); 3) true negative (no response to EMG stimulation confirmed as a correctly positioned screw on postoperative CT scans); or 4) false negative (no response to EMG stimulation but confirmed as a breach on postoperative CT scans).

Results. One hundred fifteen pedicle screws (4.7%) showed positive stimulation during intraoperative EMG monitoring. At stimulation thresholds less than 5.0, 5.0–8.0, and > 8.0 mA, the specificity of a positive response was 99.9%, 97.9%, and 95.9%, respectively. The sensitivity of a positive response at these thresholds was only 43.4%, 69.6%, and 69.6%, respectively. At a threshold less than 5.0 mA, 91% of screws with a positive EMG response were confirmed as true medial breaches. However, at thresholds of 5.0–8.0 mA or greater than 8.0 mA, a positive EMG response was associated with 89% and 100% false positives (no breaches), respectively.

Conclusions. When using intraoperative EMG monitoring, a positive response at screw stimulation thresholds less than 5.0 mA was highly specific for a medial pedicle screw breach but was poorly sensitive. A positive response to stimulation thresholds greater 5.0 mA was associated with a very high rate of false positives. The authors’ experience suggests that pedicle screws showing positive stimulation below 5.0 mA warrants intraoperative investigation for malpositioning while responses at higher thresholds are less reliable at accurately representing a medial breach

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Postoperative Magnetic Resonance Imaging Can Predict Neurological Recovery After Surgery for Cervical Spondylotic Myelopathy: A Prospective Study With Blinded Assessments

Neurosurgery 69:362–368, 2011 DOI: 10.1227/NEU.0b013e31821a418

Factors that can predict the recovery of cervical spondylotic myelopathy (CSM) patients postoperatively are of significant interest to physicians and patients and their families. Magnetic resonance imaging (MRI) scans are a common method of examination after surgery, and thus of interest as a predictor of outcome.

OBJECTIVE: To investigate whether findings on MRI at 6 months postoperatively could predict recovery at 1 year in CSM patients.

METHODS: In 52 consecutive prospective patients, MRI was performed preoperatively and 6 months postoperatively. T1 and T2 signal change (area, height, and segmentation) and spinal cord re-expansion were measured. Outcome measures evaluated at 1 year postoperatively were compared with preoperative values. Univariate and stepwise multiple regressions were undertaken.

RESULTS: Using univariate analysis, patients whose cord failed to re-expand had poorer outcome according to the modified Japanese Orthopedic Association score and Nurick score (P = .014) and grip test (P = .006) postoperatively. Stepwise multivariate regression showed lack of cord re-expansion to be predictive of prognosis postoperatively in the modified Japanese Orthopedic Association score (P = .013) and Berg Balance Scale (P = .014), and walking test (P = .011). Postoperative hyperintense T2 signal change was predictive of worse outcome on the Berg Balance Scale (P = .014) and walking test (P = .020), Nurick score (P = .001), and Short Form-36 scores (P = .020). In cases in which the T2 signal intensified, there was a poorer outcome on Nurick scores (P = .013), grip test (P = .017), and Short Form-36 scores (P = .030).

CONCLUSION: Findings on postoperative MRI at 6 months is of predictive value in determining outcomes in CSM patients. The persistence and type of T2 signal change and lack of re-expansion of the cord correlate with poorer recovery and likely reflect irreversible structural changes in the spinal cord.

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Occult Spinous Process Fractures Associated With Interspinous Process Spacers

Spine 2011;36:E1080–E1085. DOI: 10.1097/BRS.0b013e318204066a

Biomechanical cadaveric studies have suggested adequate spinous process strength to support placement of interspinous process spacers (IPS). Postoperative spinous process fractures have been reported in one%—to 5.8% of patients in previous series based on routine biplanar radiographic evaluation. However, most fractures occur between the base and midportion of the spinous process in an area that is typically diffi cult to visualize on plain radiographs due to device design.

Methods. All patients underwent preoperative biplanar plain radiographs and computed tomography (CT) of the lumbar spine to confirm anatomy favorable for IPS placement and rule out fracture or spondylolysis. Postoperatively, all patients underwent repeat CT imaging within six months of surgery, biplanar radiographs at two weeks, six weeks, three months, six months, and one year. All studies were reviewed independently by a neuroradiologist and two orthopedic spine surgeons.

Results. Fifty implants (38 L4–5, 12 L3–4) were placed in 38 patients who completed follow-up and were included in final analysis. Three IPS designs were included (34 Medtronic X-STOP titanium, 8 X-STOP PEEK, 8 Lanx Aspen). Postoperative CT revealed 11 nondisplaced spinous process fractures in 11 patients (28.9% of patients, 22% of levels). Five fractures were associated with mild to moderate lumbar back pain and six fractures were asymptomatic. No patient reported a traumatic incident. No fracture was identifiable on plain radiographs. One fracture displaced during follow-up evaluation. Three patients underwent IPS removal and laminectomy. Three fractures healed by CT in one year. Overall, patients with fractures tended toward poorer outcomes by Zurich Claudication Questionnaire (ZCQ) (28.5% vs. 34.8% improvement in symptom severity, P=  0.496; 21.4% vs. 30.7% improvement in physical function, P = 0.199) and tended toward lower satisfaction rates (50% vs. 73.7%, P = 0.24) at one year compared to patients without fracture.

Conclusion. Interspinous process spacer surgery appears associated with a higher rate of early postoperative spinous process fracture than previously reported. In all cases, in this series, plain radiographs were inadequate to identify fractures because all fractures were initially minimal or nondisplaced, many patients were osteopenic, and the metallic wings of the devices often obscured fractures. Moreover, in most patients, fractures were associated with mild or no acute localized pain. This study suggests that unrecognized spinous process fracture may be responsible for a signifi cant number of patients who experience unsatisfactory outcome after IPS surgery. CT imaging is required to identify the vast majority of such fractures.

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How I do it: cervical lateral mass screw fixation

Acta Neurochir. DOI 10.1007/s00701-011-1068-4

Cervical lateral mass screw fixation is indicated for the treatment of cervical subaxial C3-C7 lesions associated with instability.

Method The authors first describe the surgical anatomy of the subaxial cervical posterior approach. Then the Magerl technique is detailed. In particular, tricks to avoid complications are presented. The ideal screw entry point, direction, size and exit point are mentioned. A surgical video, artist’s drawings and a radiological case report are included.

Conclusion The Magerl technique is a safe and effective lateral mass fixation technique. Respecting anatomical landmarks is crucial to avoid nerve root, vertebral artery and facet joint injury.

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Cost effectiveness of disc prosthesis versus lumbar fusion in patients with chronic low back pain: randomized controlled trial with 2-year follow-up

Eur Spine J (2011) 20:1001–1011. DOI 10.1007/s00586-010-1607-3

This  randomized  controlled  health  economic study assesses the cost-effectiveness of the concept of total disc replacement (TDR) (Charité/Prodisc/Maverick) when compared with the concept of instrumented lumbar fusion (FUS) [posterior lumbar fusion (PLF) /posterior lumbar interbody fusion (PLIF)]. Social and healthcare perspectives after 2 years are reported.

In all, 152 patients were randomized  to  either  TDR  (n = 80)  or  lumbar  FUS (n = 72). Cost to society (total mean cost/patient, Swedish kronor = SEK,  standard  deviation)  for  TDR  was  SEK 599,560  (400,272),  and  for  lumbar  FUS  SEK  685,919 (422,903) (ns). The difference was not significant: SEK 86,359 (-45,605  to 214,332). TDR was significantly less costly from a healthcare perspective, SEK 22,996 (1,202 to 43,055). Number of days on sick leave among those who returned to work was 185 (146) in the TDR group, and 252 (189) in the FUS group (ns). Using EQ-5D, the total gain in quality adjusted life years (QALYs) over 2 years was 0.41 units for TDR and 0.40 units for FUS (ns). Based on EQ- 5D,  the  incremental  cost-effectiveness  ratio  (ICER)  of using TDR instead of FUS was difficult to analyze due to the ‘‘non-difference’’ in treatment outcome, which is why cost/QALY  was  not  meaningful  to  define. Using  cost- effectiveness probabilistic analysis, the net benefit (with CI) was found to be SEK 91,359 (-73,643  to 249,114) (ns). We used the currency of 2006 where 1 EURO = 9.26 SEK and 1 USD = 7.38 SEK.

It was not possible to state whether TDR or FUS is more cost-effective after 2 years. Since  disc replacement and lumbar fusion are based on different conceptual approaches, it is important to follow these results over time.

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Tubular Diskectomy vs Conventional Microdiskectomy for the Treatment of Lumbar Disk Herniation: 2-Year Results of a Double-Blind Randomized Controlled Trial

Neurosurgery 69:135–144, 2011 DOI: 10.1227/NEU.0b013e318214a98c

Transmuscular tubular diskectomy has been introduced to increase the rate of recovery, although evidence is lacking.

OBJECTIVE: To evaluate the 2-year results of tubular diskectomy compared with conventional microdiskectomy.

METHODS: Three hundred twenty-eight patients with persistent leg pain caused by lumbar disk herniation were randomly assigned to undergo tubular diskectomy (167 patients) or conventional microdiskectomy (161 patients). Main outcome measures were scores from Roland-Morris Disability Questionnaire for Sciatica, Visual Analog Scale for leg pain and low-back pain, and Likert self-rating scale of global perceived recovery.

RESULTS: On the basis of intention-to-treat analysis, there was no significant difference between tubular diskectomy and conventional microdiskectomy in Roland-Morris Disability Questionnaire for Sciatica scores during 2 years after surgery (between-group mean difference [∆] = 0.6; 95% confidence interval [CI], 20.3-1.6). Patients treated with tubular diskectomy reported more leg pain (∆ = 3.3 mm; 95% CI, 0.2-6.2) and more lowback pain (∆ = 3.0 mm; 95% CI, 20.2-6.3) than those patients treated with conventional microdiskectomy. At 2 years, 71% of patients assigned to tubular diskectomy documented a good recovery vs 77% of patients assigned to conventional microdiskectomy (odds ratio, 0.76; 95% CI, 0.45-1.28; P = .35). Repeated surgery rates within 2 years after tubular diskectomy and conventional microdiskectomy were 15% and 10%, respectively (P = .22).

CONCLUSION: Tubular diskectomy and conventional microdiskectomy resulted in similar functional and clinical outcomes. Patients treated with tubular diskectomy reported more leg pain and low-back pain, although the differences were small and not clinically relevant.

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SPORT: Does Incidental Durotomy Affect Longterm Outcomes in Cases of Spinal Stenosis?

Neurosurgery 69:38–44, 2011 DOI: 10.1227/NEU.0b013e3182134171

Incidental durotomy is a familiar encounter during surgery for lumbar spinal stenosis. The impact of durotomy on long-term outcomes remains a matter of debate.

OBJECTIVE: To determine the impact of durotomy on the long-term outcomes of patients in the Spine Patient Outcomes Research Trial (SPORT).

METHODS: The SPORT cohort participants with a confirmed diagnosis of spinal stenosis, without associated spondylolisthesis, undergoing standard, first-time, open decompressive laminectomy, with or without fusion, were followed up from baseline at 6 weeks, and 3, 6, and 12 months and yearly thereafter at 13 spine clinics in 11 US states. Patient data from this prospectively gathered database were reviewed. As of May 2009, the mean follow-up among all analyzed patients was 43.8 months.

RESULTS: Four hundred nine patients underwent first-time open laminectomy with or without fusion. Thirty-seven of these patients (9%) had an incidental durotomy. No significant differences were observed with or without durotomy in age; sex; race; body mass index; the prevalence of smoking, diabetes mellitus, and hypertension; decompression level; number of levels decompressed; or whether an additional fusion was performed. The durotomy group had significantly increased operative duration, operative blood loss, and inpatient stay. There were, however, no differences in incidence of nerve root injury, mortality, additional surgeries, or primary outcomes (Short Form-36 Bodily Pain or Physical Function scores or Oswestry Disability Index) at yearly follow-ups to 4 years.

CONCLUSIONS: Incidental durotomy during first-time lumbar laminectomy for spinal stenosis did not impact long-term outcomes in affected patients.

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Assessment of adjacent-segment mobility after cervical disc replacement versus fusion: RCT with 1 year’s results

Eur Spine J (2011) 20:934–941. DOI 10.1007/s00586-010-1588-2

Disc prostheses have been designed to restore and maintain cervical segmental motion and reduce the accelerated degeneration of the adjacent level. There is no knowledge about the reaction of the neighboured asymptomatic segments after implantation of prostheses or fusion. The effects of these procedures to segmental movement of the uninvolved vertebrae have not been subjected to studies so far.

The objective of this study was to compare the segmental motion following cervical disc replacement versus fusion and the correlation to the clinical outcome. Another aim was to compare the segmental motion of the asymptomatic segments above the treated ones and to compare both with Roentgen stereometric analysis (RSA) including the asymptomatic segments.

20 patients with one-level cervical radiculopathy scheduled for surgery were randomized to arthroplasty (10 patients, study group) or anterior cervical discectomy and fusion (10 patients, control group). Clinical results were evaluated using Visual Analogue Scale and Neck Disability Index. RSA was performed immediately postoperative, after 6 and 12 months.

The adjacent segment showed a significantly higher segmental motion in all three-dimensional axes in comparison to the segment treated with prostheses (P< 0.05). In the fusion group the segmental motion of the adjacent segment was significantly higher in all three dimensional axes (P< 0.05) at each examination time. When the adjacent level of both groups is compared, the fusion group could show a higher segmental motion in all three-dimensional axes, but without significant difference (P> 0.05) 1 year after surgery. Regarding the clinical results, there was no significant difference in pain relief between both groups (P> 0.05).

In conclusion, the adjacent segment could show a higher segmental motion, when compared with the segment either treated with prostheses or fusion. There was no significant difference in segmental motion adjacent to prosthesis or fusion. Clinical results did also show no significant difference in pain relief between both groups.

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Facetal distraction as treatment for single- and multilevel cervical spondylotic radiculopathy and myelopathy

J Neurosurg Spine 14:689–696, 2011. DOI: 10.3171/2011.2.SPINE10601
The authors discuss their successful preliminary experience with 36 cases of cervical spondylotic disease by performing facetal distraction using specially designed Goel cervical facet spacers. The clinical and radiological results of treatment are analyzed. The mechanism of action of the proposed spacers and the rationale for their use are evaluated. Between 2006 and February 2010, 36 patients were treated using the proposed technique. Of these patients, 18 had multilevel and 18 had single-level cervical spondylotic radiculopathy and/or myelopathy. The average follow-up period was 17 months with a minimum of 6 months. The Japanese Orthopaedic Association classification system, visual analog scale (neck pain and radiculopathy), and Odom criteria were used to monitor the clinical status of the patient. The patients were prospectively analyzed. The technique of surgery involved wide opening of the facet joints, denuding of articular cartilage, distraction of facets, and forced impaction of Goel cervical facet spacers into the articular cavity. Additionally, the interspinous process ligaments were resected, and corticocancellous bone graft from the iliac crest was placed and was stabilized over the adjoining laminae and facets after adequately preparing the host bone. Eighteen patients underwent single-level, 6 patients underwent 2-level, and 12 patients underwent 3-level treatment. The alterations in the physical architecture of spine and canal dimensions were evaluated before and after the placement of intrafacet joint spacers and after at least 6 months of follow-up. All patients had varying degrees of relief from symptoms of pain, radiculopathy, and myelopathy. Analysis of radiological features suggested that the distraction of facets with the spacers resulted in an increase in the intervertebral foraminal dimension (mean 2.2 mm), an increase in the height of the intervertebral disc space (range 0.4–1.2 mm), and an increase in the interspinous distance (mean 2.2 mm). The circumferential distraction resulted in reduction in the buckling of the posterior longitudinal ligament and ligamentum flavum. The procedure ultimately resulted in segmental bone fusion. No patient worsened after treatment. There was no noticeable implant malfunction. During the follow-up period, all patients had evidence of segmental bone fusion. No patient underwent reexploration or further surgery of the neck. Distraction of the facets of the cervical vertebra can lead to remarkable and immediate stabilization-fixation of the spinal segment and increase in space for the spinal cord and roots. The procedure results in reversal of several pathological events related to spondylotic disease. The safe, firm, and secure stabilization at the fulcrum of cervical spinal movements provided a ground for segmental spinal arthrodesis. The immediate postoperative improvement and lasting recovery from symptoms suggest the validity of the procedure.

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O-Arm–Guided Balloon Kyphoplasty: Prospective Single-Center Case Series of 54 Consecutive Patients

Neurosurgery 68[ONS Suppl 2]:ons250–ons256, 2011 DOI: 10.1227/NEU.0b013e31821421b9

Balloon kyphoplasty is widely used to treat vertebral compression fractures. Procedure outcome and safety are directly linked to precise radiological imaging requiring 1 or 2 C arms to allow correct visualization throughout the procedure. This minimally invasive spinal surgery is associated with radiation exposure for both patient and surgeon. In our center, we switched from using a C-arm to an O-arm image guidance system to perform balloon kyphoplasty. Our preliminary experience is reported in Acta Neurochirurgica, and the encouraging results led us to study this subject more extensively. This article presents our complete results. To the best of our knowledge, there is no comparable clinical series describing O-arm use in kyphoplasty procedures published in the literature. OBJECTIVE: To report our complete results of using the O-arm guidance system to perform balloon kyphoplasty.

METHODS: We prospectively evaluated O-arm–guided kyphoplasty procedure in 54 consecutive patients and measured x-ray exposure and fluoroscopy time.

RESULTS: The mean surgical time for the procedure was 38 minutes with a mean fluoroscopy procedure time of 3.1 minutes. The mean fluoroscopy time by level was 2.5 minutes. Mean irradiation dose by procedure was 220 mGy and by level was 166 mGy. There was a significant reduction in fluoroscopy time and x-ray exposure from 5.1 minutes with classic C-arm use to 3.1 minutes when with O-arm use without additional time required for positioning the system.

CONCLUSION: With this new intraoperative system, the overall surgical and fluoroscopy times can be further reduced in the near future.

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Long-term Outcome After Microendoscopic Diskectomy for Lumbar Disk Herniation: A Prospective Clinical Study With a 5-Year Follow-up

Neurosurgery 68:1568–1575, 2011 DOI: 10.1227/NEU.0b013e31820cd16a

Several authors have reported results obtained with the microendoscopic diskectomy (MED) technique, but the long-term outcome has not been described. This report summarizes our clinical experience with the lumbar MED technique with a long-term follow-up period.

OBJECTIVE: To evaluate the efficacy of the MED for lumbar disk herniation and to report long-term outcome and complications (5-year follow-up).

METHODS: One hundred twenty consecutive patients with lumbar disk herniation were treated with the METRx system.We included all types of lumbar herniated disks: contained, not contained, foraminal, and migrated disk herniations. The results were evaluated with the Visual Analog Scale (VAS) pain score, Oswestry Disability Index score, patient satisfaction questionnaire, and modified Macnab criteria.

RESULTS: The average age of patients was 41 years; 65 were men and 55 were women. The most commonly affected level was L5-S1 (54.2%). The follow-up time after surgery was 5 years in all cases. We obtained good or excellent results in 75% of patients and regular results in 18%. Good subjective satisfaction was observed with surgery in 92% of patients. The mean decrease in the Oswestry Disability Index score was 52.8 ± 21.6; the mean decrease in leg VAS score was 6.1 ± 2.3; and the mean decrease in lumbar VAS score was 1.9 ± 3.3. Adjusted mean differences were statistically significant in all cases (P < .05).

CONCLUSION: MED not only reduces the incision, tissue damage, and postoperative period of incapacity but also offers long-term results comparable to those of conventional techniques.

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Cauda equina syndrome: a review of the current clinical and medico-legal position

Eur Spine J (2011) 20:690–697. DOI 10.1007/s00586-010-1668-3

Cauda equina syndrome (CES) is a rare condition with a disproportionately high medico-legal profile. It occurs most frequently following a large central lumbar disc herniation, prolapse or sequestration.

Review of the literature indicates that around 50–70% of patients have urinary retention (CES-R) on presentation with 30–50% having an incomplete syndrome (CES-I). The latter group, especially if the history is less than a few days, usually requires emergency MRI to confirm the diagnosis followed by prompt decompression by a suitably experienced surgeon. Every effort should be made to avoid CES-I with its more favourable prognosis becoming CES-R while under medical supervision either before or after admission to hospital. The degree of urgency of early surgery in CES-R is still not in clear focus but it cannot be doubted that earliest decompression removes the mechanical and perhaps chemical factors which are the causes of progressive neurological damage.

A full explanation and consent procedure prior to surgery is essential in order to reduce the likelihood of misunderstanding and litigation in the event of a persistent neurological deficit.

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Robotic Digital Subtraction Angiography Systems Within the Hybrid Operating Room

Neurosurgery 68:1427–1433, 2011 DOI: 10.1227/NEU.0b013e31820b4f1c

Fully equipped high-end digital subtraction angiography (DSA) within the operating room (OR) environment has emerged as a new trend in the fields of neurosurgery and vascular surgery.

OBJECTIVE: To describe initial clinical experience with a robotic DSA system in the hybrid OR.

METHODS: A newly designed robotic DSA system (Artis zeego; Siemens AG, Forchheim, Germany) was installed in the hybrid OR. The system consists of a multiaxis robotic C arm and surgical OR table. In addition to conventional neuroendovascular procedures, the system was used as an intraoperative imaging tool for various neurosurgical procedures such as aneurysm clipping and spine instrumentation.

RESULTS: Five hundred one neurosurgical procedures were successfully conducted in the hybrid OR with the robotic DSA. During surgical procedures such as aneurysm clipping and arteriovenous fistula treatment, intraoperative 2-/3-dimensional angiography and C-arm-based computed tomographic images (DynaCT) were easily performed without moving the OR table. Newly developed virtual navigation software (syngo iGuide; Siemens AG) can be used in frameless navigation and in access to deep-seated intracranial lesions or needle placement.

CONCLUSION: This newly developed robotic DSA system provides safe and precise treatment in the fields of endovascular treatment and neurosurgery.

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Prospective, Randomized, Double-Blind Clinical Study Evaluating the Correlation of Clinical Outcomes and Cervical Sagittal Alignment

Neurosurgery 68:1309–1316, 2011. DOI:10.1227/NEU.0b013e31820b51f3

Sagittal alignment of the cervical spine has received increased attention in the literature as an important determinant of clinical outcomes after anterior cervical diskectomy and fusion. Surgeons use parallel or lordotically fashioned grafts depending on preference or simple availability.

OBJECTIVE: To quantitatively assess and compare cervical sagittal alignment and clinical outcome when lordotic or parallel allografts were used for fusion.

METHODS: A prospective, randomized, double-blind clinical study that enrolled 122 patients was performed. The mean follow-up was 37.5 months (range, 12-54 months).

RESULTS: The mean postoperative cervical sagittal alignment was 19 (range, 27-36) and 18 (range, 27-37) in the lordotic and parallel graft patient groups, respectively. The mean segmental sagittal alignment was 6 (range, 24-19) and 7 (range, 23-19) in the lordotic and parallel graft patient groups, respectively. There were no statistically significant differences in clinical outcome scores between the lordotic and parallel graft patient groups. However, patients who had maintained or improved segmental sagittal alignment, regardless of graft type, achieved a higher degree of improvement in Short Form-36 Physical Component Summary and Neck Disability Index scores. This was statistically significant (P , .038).

CONCLUSION: The use of lordotically shaped allografts does not increase cervical/ segmental sagittal alignment or improve clinical outcomes. Maintaining a consistent segmental sagittal alignment or increasing segmental lordosis was related to a higher degree of improvement in clinical outcomes.

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Surgical management and outcome of schwannomas in the craniocervical region

J Neurosurg 114:1257–1267, 2011. DOI: 10.3171/2010.5.JNS0966

Schwannomas occupying the craniocervical junction (CCJ) are rare and usually originate from the jugular foramen, hypoglossal nerves, and C-1 and C-2 nerves. Although they may have different origins, they may share the same symptoms, surgical approaches, and complications. An extension of these lesions along the posterior fossa cisterns, foramina, and spinal canal—usually involving various cranial nerves (CNs) and the vertebral and cerebellar arteries—poses a surgical challenge. The primary goals of both surgical and radiosurgical management of schwannomas in the CCJ are the preservation and restoration of function of the lower CNs, and of hearing and facial nerve function. The origins of schwannomas in the CCJ and their clinical presentation, surgical management, adjuvant stereotactic radiosurgery, and outcomes in 36 patients treated at Barrow Neurological Institute (BNI) are presented.

Methods. Between 1989 and 2009, 36 patients (mean age 43.6 years, range 17–68 years) with craniocervical schwannomas underwent surgical resection at BNI. The records were reviewed retrospectively regarding clinical presentation, radiographic assessment, surgical approaches, adjuvant therapies, and follow-up outcomes.

Results. Headache or neck pain was present in 72.2% of patients. Cranial nerve impairments, mainly involving the vagus nerve, were present in 14 patients (38.9%). Motor deficits were found in 27.8% of the patients. Sixteen tumors were intra- and extradural, 15 were intradural, and 5 were extradural. Gross-total resection was achieved in 25 patients (69.4%). Adjunctive radiosurgery was used in the management of residual tumor in 8 patients; tumor control was ultimately obtained in all cases.

Conclusions. Surgical removal, which is the treatment of choice, is curative when schwannomas in the CCJ are excised completely. The far-lateral approach and its variations are our preferred approaches for managing these lesions. Most common complications involve deficits of the lower CNs, and their early recognition and rehabilitation are needed. Stereotactic radiosurgery, an important tool for the management of these tumors as adjuvant therapy, can help decrease morbidity rates.

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