Prospective, randomized, double-blinded clinical trial comparing PEEK and allograft spacers in patients undergoing transforaminal lumbar interbody fusion surgeries

BACKGROUND CONTEXT

Allograft and polyether-ether-ketone (PEEK) radiographic, biomechanical, histological properties have been extensively studied and both spacers have their advantages and shortcomings. There are no comparative randomized or double-blinded spinal fusion clinical trials reported to date.

PURPOSE

The study's primary objective was to prospectively investigate clinical and radiological outcomes in patients undergoing lumbar interbody fusions and randomized to receive either PEEK or structural bone allografts.

STUDY DESIGN/ SETTING

A prospective, randomized, double-blinded clinical trial was initiated at a single center.

PATIENT SAMPLE

A total of 138 patients were enrolled, randomized and 121 patients completed the study.

OUTCOME MEASURES

The primary clinical outcome parameters were scored from standardized patient-reported questionnaires. The severity of lower back and leg pain was evaluated using the 11-point Visual Analog Scale (VAS). The Oswestry Disability Questionnaire was used to evaluate chronic disability and activities of daily living. Health-related quality of life and functional outcomes were assessed using Health-related Quality of Life Questionnaire (SF-36 v2). Two scores within the scoring algorithm were analyzed: Physical Component (PCS) and Mental Component Summary (MCS). The primary radiological outcomes included restoration and maintenance of vertebral body height, lumbar sagittal and segmental alignment, and fusion status.

METHODS

All patients were followed for 2 years ± 2 months; radiographic and clinical outcomes were assessed at 3, 6, 12 and 24 months with an additional follow-up at 3 weeks for radiographic assessment.

RESULTS

A total of 138 patients undergoing transforaminal lumbar interbody fusions (TLIF) were randomized (1:1) to receive either cortical allograft or PEEK interbody lordotic spacers. Although no differences were detected between the allograft and PEEK patient groups at any of the follow-up time points, there was a highly significant (p<.0001) improvement in all clinical outcome measures. Overall, evidence of radiographic fusion was achieved in 118 (97.5%) patients at the 24 months follow-up. Three patients, all in the allograft group, had pseudoarthrosis and underwent revision surgeries. Postoperative improvement of sagittal alignment, anterior (ABH) or posterior body height (PBH) was initially achieved, but it was mainly lost or reduced at the final follow-up and there were no statistically significant differences between the groups. At the end of the study, improvement and maintenance of lumbar lordosis were achieved in 43.3% and 49.2% patients and segmental alignment in 38.3% and 36.1% for the allograft and PEEK patient groups, respectively. Similarly, ABH was improved and maintained in 28.3% and 36.1% patients and PBH in 28.3% and 44.3% for the allograft and PEEK groups, respectively.

CONCLUSIONS

Although allograft-assisted surgeries may have reduced fusion rates, the study findings demonstrated that TLIF surgery with two different types of cages and in conjunction with rhBMP-2 resulted in similar radiological or clinical outcomes and a highly statistically significant improvement in all clinical outcome measures at the end of the study regardless of the randomization group.

Local Retropharyngeal Space Anesthetic for Dysphagia Reduction after Anterior Cervical Discectomy and Fusion Surgery: A Single-Center, Prospective, Randomized, Double-Blinded, Placebo-Controlled Clinical Trial

OBJECTIVE

The main objective of this study was to analyze the ability of local anesthetic instillation into the retropharyngeal space to reduce dysphagia symptoms and occurrence rates in patients undergoing anterior cervical discectomy and fusion (ACDF) procedures.

METHODS

A single-center, prospective, randomized, double-blinded, and placebo-controlled clinical study was performed. We enrolled patients undergoing one- or two-level ACDF procedures for cervical degenerative disc disease with disc herniation, radiculopathy and/or myelopathy symptoms. The patients were randomly assigned (1:1 ratio) to receive either 0.5% bupivacaine hydrochloride or 0.9% NaCl solution.

RESULTS

Forty-three (74%) and 41 (77%) of patients reported dysphagia symptoms at the time of discharge in the investigational and control groups, respectively. There were no statistically significant differences in duration of dysphagia symptoms, Swallowing-Quality of Life (SWAL-QOL) survey or pain scores between the investigational and control patient groups at any of the follow-up time points. Controlling for independent variables, only younger age significantly predicted dysphagia symptoms at discharge, 2-week, and 3-month follow-ups (P ≤ 0.03; R ≥ -0.038; OR 0.96, 95% CI 0.93-0.99. Female sex was associated with lower SWAL-QOL scores at discharge (P = 0.046; R = 0.87; OR 2.38, 95% CI 1.02-5.56). A total of 8 (13.8%) and 6 (11.3%) patients in the investigational and control groups, respectively, were referred to a specialist or underwent speech therapy for their dysphagia symptoms. There were no adverse reactions to the study drug observed.

CONCLUSIONS

Local retropharyngeal space anesthetic instillation did not reduce dysphagia symptoms or occurrence rates in patients undergoing anterior discectomy and fusion surgeries.

Medical complications and mortality in octogenarians undergoing elective spinal fusion surgeries

BACKGROUND

The consequences of suffering postoperative complications in elderly undergoing spinal surgeries may be different compared to younger patients. The primary objective of this study was to identify the types and frequency of medical complications and mortality rates in patients 80 years of age or older undergoing elective spinal fusion surgeries for degenerative spinal disease.

METHODS

A prospective observational study with a retrospective chart review was performed, which included all consecutive patients ≥80 years old undergoing elective spinal fusion surgeries from May 2012 to August 2015. We identified a total of 95 patients, of which 39 cervical and 56 lumbar surgeries were performed. There were 41 female and 54 male patients with the mean age of 82.8 years (range, 80-91). The perioperative complications were allocated into the following categories: infection, pulmonary, cardiac, gastrointestinal, hematologic, urologic, neurovascular, thromboembolic, and other. Baseline and postoperative clinical outcome scores were compared to evaluate efficacy.

RESULTS

The mean follow-up time was 14.8 months (range, 5 days to 37 months) with an overall mortality rate of 8.4%. The 30-day, 90-day, and 1-year mortality rates were 2.1, 2.1, and 4.2%, respectively. There were 53.9 and 71.4% patients with complications in the cervical and lumbar patient groups, respectively. The presence of general comorbidities and the number of intervertebral levels predicted the occurrence of perioperative complications. Also, longer OR times were associated with a higher number of complications per patient and the occurrence of a UTI. Dysphagia was a significant predictor in developing pneumonia and atelectasis.

CONCLUSIONS

The incidence of perioperative medical complications and mortality rates in octogenarians undergoing elective spinal surgeries are quite high. The benefits of having surgery must be weighed against the risks of not only surgical but also adverse medical events. An informed decision-making process should include discussion of potential postoperative morbidity specific to this patient population in order to guide patient's acceptance of higher risks and expectations postoperatively. It is also important to identify potential complications and adapt preventive measures in order to help minimize them in this patient population.

Prediction based on preoperative opioid use of clinical outcomes after transforaminal lumbar interbody fusions

OBJECTIVE

Opioid analgesics have become some of the most prescribed drugs in the world, despite the lack of long-term studies evaluating the benefits of opioid medications versus their risks associated with chronic use. In addition, long-term opioid use may be associated with worse long-term clinical outcomes. The primary objective of this study was to evaluate whether preoperative opioid use predicted inferior clinical outcomes among patients undergoing transforaminal lumbar interbody fusion (TLIF) for symptomatic lumbar degenerative disc disease.

METHODS

The authors of this observational study prospectively enrolled 93 patients who underwent 1-level to 2-level TLIFs in 2011–2014; the patient cohort was divided into 2 groups according to preoperative opioid use or no such use. Visual analog scale (VAS) scores for low-back pain and leg pain, Oswestry Disability Index scores, and the scores of the mental component summary (MCS) and physical component summary (PCS) on the 36-Item Short Form Health Survey were used to assess pain, disability, and health-related quality of life outcomes, respectively. The clinical scores for the 2 groups were determined preoperatively and at a 12-month follow-up examination.

RESULTS

In total, 60 (64.5%) patients took prescribed opioid medications preoperatively. Compared with those not taking opioids preoperatively, these patients had significantly higher VAS scores for low-back pain (p = 0.016), greater disability (p = 0.013), and lower PCS scores (p = 0.03) at the 12-month follow-up. The postoperative MCS scores were also significantly lower (p = 0.035) in the opioid-use group, but these lower scores were due to significantly lower baseline MCS scores in this group. A linear regression analysis did not detect opioid dose–related effects on leg and back pain, disability, and MCS and PCS scores, suggesting that poorer outcomes are not significantly correlated with higher opioid doses taken by the patients.

CONCLUSIONS

The use of opioid medications to control pain before patients underwent lumbar fusion for degenerative lumbar conditions was associated with less favorable clinical outcomes postoperatively. This is the first study that has demonstrated this association in a homogeneous cohort of patients undergoing TLIF; this association should be studied further to evaluate the conclusions of the present study.

Clinical trial registration no.: NCT01406405 (clinicaltrials.gov)

RhBMP-2-induced radiculitis in patients undergoing transforaminal lumbar interbody fusion: relationship to dose

BACKGROUND CONTEXT

Recombinant human bone morphogenetic protein-2 (rhBMP-2) remains the primary synthetic osteoinductive material used in spinal fusion surgery today. The early inflammation reaction to rhBMP-2 manifesting with radicular symptoms has been previously reported in patients undergoing transforaminal lumbar interbody fusion (TLIF). There is a disagreement with regard to the factors affecting its occurrence and whether such symptoms are dose dependent.

PURPOSE

The purpose of this analysis was to determine the incidence of rhBMP-2-induced radiculitis and its relationship to dose.

STUDY DESIGN/SETTING

A retrospective cohort analysis was performed of the prospectively collected data.

PATIENT SAMPLE

All consecutive patients (n=204) who underwent one- or two-level TLIF and instrumented posterolateral fusion with an off-label rhBMP-2 use were included in this analysis.

OUTCOME MEASURES

The patients who developed new radicular symptoms after initial improvement postoperatively and had sterile fluid collections indicative of inflammatory process, or in the absence of any structural abnormalities that would explain these symptoms on imaging studies, were deemed to have rhBMP-2-induced radiculitis.

METHODS

Magnetic resonance imaging (MRI) scans were obtained for all patients who developed postoperative radicular symptoms. Correlations between the total rhBMP-2 dose, dose per spinal level, and incidence of radiculitis were evaluated while controlling for age, sex, number of TLIF levels, and surgeon.

RESULTS

The incidence of postoperative radiculitis was 11.3% (23 out of 204). The average total rhBMP-2 dose was 4.9 mg (range=2.1-12) and the average dose per spinal level was 3.8 mg (range=1.05-12). Logistic regression analysis did not identify any significant correlations between the rhBMP-2 doses and the incidence of radiculitis (p=.6).

CONCLUSION

The incidence of rhBMP-2-induced radiculitis in patients undergoing TLIF is quite high, but there were no dose-related correlations found. The study, however, cannot rule out a possibility that a larger variation in bone morphogenetic protein (BMP) doses could still be a factor in the development of rhBMP-2-associated radiculitis.

Post-Treatment Gliosarcoma Extension into the Pterygomaxillary Fossa: Literature Review and Case Report

Only four primary gliosarcoma case reports are described in the literature with transcranial (intradural to extradural) penetration into the region of the infratemporal fossa. This is the first report of a primary glioblastoma (GBM) that evolved into secondary or post-treatment gliosarcoma without evidence of a second de novo tumor and with extension into the left pterygomaxillary fossa.

Case Series of Anterior Intervertebral Graft Extrusions in Transforaminal Lumbar Interbody Fusion Surgeries

BACKGROUND

According to the published reports, revision surgery is sometimes recommended even in patients with asymptomatic anterior lumbar intervertebral graft migrations. The main purpose of this chart review study was to report on the clinical course and outcomes of patients who had anterior intervertebral graft extrusions after transforaminal lumbar interbody fusion (TLIF).

METHODS

From July 2002 to July 2014, 1259 consecutive TLIF surgeries were performed. These were reviewed, and patients who had anterior intervertebral graft extrusions were identified.

RESULTS

The incidence of graft extrusion was 0.6% (7 of 1259 patients). There were 6 female patients and 1 male patient with an average age of 65.7 years (range, 44-80 years). All patients underwent TLIF with bilateral pedicle screw fixation, and 6 received recombinant human bone morphogenetic protein-2. Graft migrations were diagnosed between 5 days and 8 months postoperatively except for 2 cases in which migration occurred intraoperatively. The patients were closely followed for an average of 27.4 months (range, 12-43 months). All patients remained asymptomatic during the follow-up period and had solid fusion despite extrusions with an average time to fusion of 13 months (range, 10-18 months). No other adverse events occurred during the follow-up period.

CONCLUSIONS

The risks of additional and highly invasive revision surgery should be weighed against the potential short-term and long-term complications associated with graft extrusions or migrations. It was demonstrated that fusion may take longer but can be achieved, and close observation may be adequate for asymptomatic patients.

A Preliminary Report on the CO2 Laser for Lumbar Fusion: Safety, Efficacy and Technical Considerations

The purpose of this study was to evaluate potential technical advantages of the CO2 laser technology in mini-open transforaminal lumbar interbody fusion (TLIF) surgeries and report our preliminary clinical data on the safety and clinical outcomes. There is currently no literature discussing the recently redeveloped CO2 laser technology application for lumbar fusion. Safety and clinical outcomes were compared between two groups: 24 patients that underwent CO2 laser-assisted one-level TLIF surgeries and 30 patients that underwent standard one-level TLIF surgeries without the laser. There were no neural thermal injuries or other intraoperative laser-related complications encountered in this cohort of patients. At a mean follow-up of 17.4 months, significantly reduced lower back pain scores (P=0.013) were reported in the laser-assisted patient group compared to a standard fusion patient group. Lower extremity radicular pain intensity scores were similar in both groups. Laser-assisted TLIF surgeries showed a tendency (P = 0.07) of shorter operative times that was not statistically significant. Based on this preliminary clinical report, the safety of the CO2 laser device for lumbar fusion surgeries was assessed. There were no neural thermal injuries or other intraoperative laser-related complications encountered in this cohort of patients. Further investigation of CO2 laser-assisted lumbar fusion procedures is warranted in order to evaluate its effect on clinical outcomes.

The duration of symptoms and clinical outcomes in patients undergoing anterior cervical discectomy and fusion for degenerative disc disease and radiculopathy

BACKGROUND CONTEXT

There have been controversial reports published in the literature on the duration of symptoms (DOS) and clinical outcome correlation in patients undergoing anterior cervical discectomy and fusion (ACDF) for painful degenerative disc disease and radiculopathy.

PURPOSE

The primary purpose of this study was to analyze if the DOS has any effect on clinical outcomes.

STUDY DESIGN/SETTING

A post hoc analysis was performed on an original prospective clinical study analyzing clinical outcomes and cervical sagittal alignment correlations.

PATIENTS SAMPLE

Fifty-eight patients undergoing one- or two-level ACDF surgeries for cervical degenerative radiculopathy were analyzed.

OUTCOME MEASURES

Standardized questionnaires were used to evaluate clinical outcomes. Neck and arm pain was evaluated using (Visual Analog Scale [VAS]). Two scales of Health-Related Quality-of-Life Questionnaire (Short-Form 36 Health Survey [SF-36]) were used for this study: the physical component summary (PCS) and mental component summary (MCS). Neck disability index (NDI) was used to evaluate chronic disability in activities of daily living. The patients completed a self-reported Patient Satisfaction with Results Survey.

METHODS

Patients who had previous or redo surgeries, were diagnosed with myelopathy or had more than two-level ACDF surgeries were excluded, leaving a total of 58 patients. The mean follow-up was 37.2 months (range 12-54). Patients were divided into two groups for clinical outcome analyses according to the DOS: patients who had surgery within 6 months (n=29) or more than 6 months (n=29) after becoming symptomatic.

RESULTS

There were no statistically significant differences in any demographic or clinical parameters among the patient groups. Controlling for preoperative scores, the patients who had surgery within 6 months reported significantly higher reduction (p=.04) in arm pain scores compared with the patients who waited more than 6 months. No significant differences were detected in postoperative neck pain VAS (p=.3), NDI (p=.06), SF-36 PCS (p=.08), and MCS (p=.8) scores.

CONCLUSIONS

Neck and upper extremity pain can be successfully treated conservatively. In those cases, when surgical intervention is pursued, patients with shorter DOS have better improvement in radiculopathy symptoms that is statistically significant.

The accuracy of pedicle screw placement using intraoperative image guidance systems

OBJECT

Several retrospective studies have demonstrated higher accuracy rates and increased safety for navigated pedicle screw placement than for free-hand techniques; however, the accuracy differences between navigation systems has not been extensively studied. In some instances, 3D fluoroscopic navigation methods have been reported to not be more accurate than 2D navigation methods for pedicle screw placement. The authors of this study endeavored to identify if 3D fluoroscopic navigation methods resulted in a higher placement accuracy of pedicle screws.

METHODS

A systematic analysis was conducted to examine pedicle screw insertion accuracy based on the use of 2D, 3D, and conventional fluoroscopic image guidance systems. A PubMed and MEDLINE database search was conducted to review the published literature that focused on the accuracy of pedicle screw placement using intraoperative, real-time fluoroscopic image guidance in spine fusion surgeries. The pedicle screw accuracy rates were segregated according to spinal level because each spinal region has individual anatomical and morphological variations. Descriptive statistics were used to compare the pedicle screw insertion accuracy rate differences among the navigation methods.

RESULTS

A total of 30 studies were included in the analysis. The data were abstracted and analyzed for the following groups: 12 data sets that used conventional fluoroscopy, 8 data sets that used 2D fluoroscopic navigation, and 20 data sets that used 3D fluoroscopic navigation. These studies included 1973 patients in whom 9310 pedicle screws were inserted. With conventional fluoroscopy, 2532 of 3719 screws were inserted accurately (68.1% accuracy); with 2D fluoroscopic navigation, 1031 of 1223 screws were inserted accurately (84.3% accuracy); and with 3D fluoroscopic navigation, 4170 of 4368 screws were inserted accurately (95.5% accuracy). The accuracy rates when 3D was compared with 2D fluoroscopic navigation were also consistently higher throughout all individual spinal levels.

CONCLUSIONS

Three-dimensional fluoroscopic image guidance systems demonstrated a significantly higher pedicle screw placement accuracy than conventional fluoroscopy or 2D fluoroscopic image guidance methods.

Complications in patients undergoing combined transforaminal lumbar interbody fusion and posterior instrumentation with deformity correction for degenerative scoliosis and spinal stenosis

Background:

Utilization of the transforaminal lumbar interbody fusion (TLIF) approach for scoliosis offers the patients deformity correction and interbody fusion without the additional morbidity associated with more invasive reconstructive techniques. Published reports on complications associated with these surgical procedures are limited. The purpose of this study was to quantify the intra- and postoperative complications associated with the TLIF surgical approach in patients undergoing surgery for spinal stenosis and degenerative scoliosis correction.

Methods:

This study included patients undergoing TLIF for degenerative scoliosis with neurogenic claudication and painful lumbar degenerative disc disease. The TLIF technique was performed along with posterior pedicle screw instrumentation. The average follow-up time was 30 months (range, 15–47).

Results:

A total of 29 patients with an average age of 65.9 years (range, 49–83) were evaluated. TLIFs were performed at 2.2 levels on average (range, 1–4) in addition to 6.0 (range, 4–9) levels of posterolateral instrumented fusion. The preoperative mean lumbar lordosis was 37.6° (range, 16°–55°) compared to 40.5° (range, 26°–59.2°) postoperatively. The preoperative mean coronal Cobb angle was 32.3° (range, 15°–55°) compared to 15.4° (range, 1°–49°) postoperatively. The mean operative time was 528 min (range, 276–906), estimated blood loss was 1091.7 mL (range, 150–2500), and hospitalization time was 8.0 days (range, 3–28). A baseline mean Visual Analog Scale (VAS) score of 7.6 (range, 4–10) decreased to 3.6 (range, 0–8) postoperatively. There were a total of 14 (49%) hardware and/or surgical technique related complications, and 8 (28%) patients required additional surgeries. Five (17%) patients developed pseudoarthrosis. The systemic complications (31%) included death (1), cardiopulmonary arrest with resuscitation (1), myocardial infarction (1), pneumonia (5), and pulmonary embolism (1).

Conclusion:

This study suggests that although the TLIF approach is a feasible and effective method to treat degenerative adult scoliosis, it is associated with a high rate of intra- and postoperative complications and a long recovery process.

Effect on clinical outcomes of patient pain expectancies and preoperative Mental Component Summary scores from the 36-Item Short Form Health Survey following anterior cervical discectomy and fusion

Object

The primary purpose of this study was to analyze what effect preoperative patient expectations and 36-Item Short Form Health Survey (SF-36) Mental Component Summary (MCS) scores have on clinical outcomes. To the authors' knowledge, there are no prospective studies that have examined the effects of both preoperative pain expectations and SF-36 MCS scores on clinical outcomes and satisfaction with results following anterior cervical discectomy and fusion (ACDF).

Methods

This study analyzed 79 patients (38 men, 41 women) undergoing 1- to 3-level ACDF surgery. Preoperatively, patients were divided into 2 groups for the expectation analyses: patients who expected complete resolution of pain postoperatively (44 total) and those who expected some residual pain (35 total) postoperatively. Preoperative SF-36 MCS scores were used to test the possible effects of mental health on clinical outcomes and satisfaction. Clinical outcomes were evaluated using visual analog scales (VASs) for neck/arm pain, Neck Disability Index (NDI), SF-36 Physical Component Summary (PCS)/MCS, and patient satisfaction with results scales. The mean follow-up duration was 38.8 months (range 7–59 months).

Results

All postoperative measures depicted significant improvement overall. Patients who expected no pain reported lower postoperative neck/arm pain scores (p < 0.02), higher SF-36 MCS scores (p = 0.04), and higher satisfaction with results scores (p = 0.01) compared with patients who expected some pain, after controlling for their respective preoperative scores. Higher preoperative SF-36 MCS scores predicted significantly lower postoperative neck pain (p = 0.003) and NDI (p = 0.004) scores, as well as higher postoperative SF-36 PCS (p = 0.002), SF-36 MCS (p = 0.001), and satisfaction (p = 0.03) scores, after controlling for their respective preoperative scores.

Conclusions

Patients who expected no pain postoperatively reported better scores on the nonstandardized outcome measure scales (VAS arm/neck, satisfaction with results), and higher SF-36 MCS scores. Higher preoperative MCS scores were related to better overall (standardized and nonstandardized) clinical outcomes (VAS neck, NDI, SF-36 PCS/MCS, and satisfaction with results). The results suggest that optimism in patients' expectations as well as mental well-being are related to improved clinical outcomes and higher patient satisfaction.

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

BACKGROUND:

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, −7°-36°) and 18° (range, −7°-37°) in the lordotic and parallel graft patient groups, respectively. The mean segmental sagittal alignment was 6° (range, −4°-19°) and 7° (range, −3°-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 &lt; .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.

Minimally invasive versus open transforaminal lumbar interbody fusion

Background

Available clinical data are insufficient for comparing minimally invasive (MI) and open approaches for transforaminal lumbar interbody fusion (TLIF). To date, a paucity of literature exists directly comparing minimally invasive (MI) and open approaches for transforaminal lumbar interbody fusion (TLIF). The purpose of this study was to directly compare safety and effectiveness for these two surgical approaches.

Materials and Methods

Open or minimally invasive TLIF was performed in 63 and 76 patients, respectively. All consecutive minimally invasive TLIF cases were matched with a comparable cohort of open TLIF cases using three variables: diagnosis, number of spinal levels, and history of previous lumbar surgery. Patients were treated for painful degenerative disc disease with or without disc herniation, spondylolisthesis, and/or stenosis at one or two spinal levels. Clinical outcome (self-report measures, e.g., visual analog scale (VAS), patient satisfaction, and MacNab's criteria), operative data (operative time, estimated blood loss), length of hospitalization, and complications were assessed. Average follow-up for patients was 37.5 months.

Results:

The mean change in VAS scores postoperatively was greater (5.2 vs. 4.1) in theopen TLIF patient group (P = 0.3). MacNab's criteria score was excellent/good in 67% and 70% (P = 0.8) of patients in open and minimally invasive TLIF groups, respectively. The overall patient satisfaction was 72.1% and 64.5% (P = 0.4) in open and minimally invasive TLIF groups, respectively. The total mean operative time was 214.9 min for open and 222.5 min for minimally invasive TLIF procedures (P = 0.5). The mean estimated blood loss for minimally invasive TLIF (163.0 ml) was significantly lower (P < 0.0001) than the open approach (366.8 ml). The mean duration of hospitalization in the minimally invasive TLIF (3 days) was significantly shorter (P = 0.02) than the open group (4.2 days). The total rate of neurological deficit was 10.5% in the minimally invasive TLIF group compared to 1.6% in the open group (P = 0.02).

Conclusions:

Minimally invasive TLIF technique may provide equivalent long-term clinical outcomes compared to open TLIF approach in select population of patients. The potential benefit of minimized tissue disruption, reduced blood loss, and length of hospitalization must be weighted against the increased rate of neural injury-related complications associated with a learning curve.

Cyberknife radiosurgery for trigeminal neuralgia treatment: a preliminary multicenter experience

OBJECTIVE

Radiosurgery has gained acceptance as a treatment option for trigeminal neuralgia. We report our preliminary multicenter experience treating trigeminal neuralgia with the CyberKnife (Accuray, Inc., Sunnyvale, CA).

METHODS

A total of 95 patients were treated for idiopathic trigeminal neuralgia between May 2002 and October 2005. Radiosurgical dose and volume parameters were retrospectively analyzed in relation to pain response, complications, and recurrence of symptoms. Optimal treatment parameters were identified for patients who had excellent and sustained pain relief with no complications, including severe or moderate hypesthesia.

RESULTS

Excellent pain relief was initially experienced by 64 out of 95 patients (67%). The median time to pain relief was 14 days (range, 0.3-180 d). Posttreatment numbness occurred in 45 (47%) of the patients treated. Using higher radiation doses and treating longer segments of the nerve led to both better pain relief and a higher incidence of hypesthesia. The presence of posttreatment numbness was predictive of better pain relief. The overall rate of complications was 18%. At the mean follow-up time of 2 years, 47 of the 95 patients (50%) had sustained pain relief, all of whom were completely off pain medications.

CONCLUSION

The results of this study suggest the following optimal radiosurgical treatment parameters for treatment of idiopathic trigeminal neuralgia: a median maximal dose of 78 Gy (range, 70-85.4 Gy) and a median length of the nerve treated of 6 mm (range, 5-12 mm).

Neck pain in multisport athletes

OBJECT

The sport of triathlon is very physically demanding and has experienced rapid growth in recent years. The number of triathletes seen for spine disorders at neurosurgery clinics is increasing. Neck pain and overuse injuries have not been adequately studied in multisport athletes. The authors undertook an epidemiological study to establish the lifetime incidence of neck pain and the prevalence of possible discogenic pain, and to identify risk factors among triathletes in the Boulder, Colorado area.

METHODS

An online questionnaire was developed to collect information about physical characteristics, training habits, athletic status, number of races completed, and neck pain among triathletes. The incidence of possible cervical discogenic pain was defined according to the duration of symptoms for the most recent pain episode.

RESULTS

One hundred and sixty-four athletes responded to the questionnaire. The lifetime incidence of neck pain was 47.6% (78 athletes), with 15.4% possibly being of discogenic origin based on the duration of symptoms. Approximately 64% of responding athletes reported that their neck pain was sports related. Although the number of previous triathlons was not predictive of neck pain, total years in the sport (p = 0.029) and number of previous sports-related injuries (p < 0.0001) were.

CONCLUSIONS

Two major risk factors for long-term spinal problems in triathletes are sports-related injuries and overuse. This report is one of the first comprehensive studies of neck pain and overuse injury in multisport athletes.

The safety of instrumented outpatient anterior cervical discectomy and fusion

BACKGROUND CONTEXT

Reported hospitalization times after an anterior cervical discectomy and fusion (ACDF) procedure range between 20 hours to 4 days. Reasons for this wide variation are manifold, but the safety of an instrumented ACDF in the setting of a hostile medical-legal climate is most likely the primary concern influencing such a discrepancy.

PURPOSE

The purpose of this study was to evaluate the safety and feasibility of performing single, two- and three-level ACDF with instrumentation on an outpatient or 23-hour observation period basis in order to potentially diminish the additional cost of hardware without compromising the purported benefits of surgery.

STUDY DESIGN/SETTING

A retrospective chart review of patients undergoing instrumented ACDF on an outpatient basis was performed.

PATIENT SAMPLE

A total of 103 patients with neck pain and/or radiculopathy undergoing ACDF were enrolled into this study.

OUTCOME MEASURES

Included the evaluation of intraoperative and perioperative complications, which were reported for a total of 6 months after surgery. Clinical examination and radiographical assessment, including plain radiographs and computed tomography and magnetic resonance imaging (when required), were performed to assess complications.

METHODS

Complications were divided into two groups: major and minor. Major complications included vertebral fracture and dehydration resulting in readmission. Minor complications included allergic reactions to medications that did not require hospitalization, and transient (< or = 3 months) neurologic deficit. A comprehensive literature search and meta-analysis was performed to generate a large comparison group in order to compare the complication rates in our outpatient series to those reported in the literature.

RESULTS

A total of 99 patients (96.1%) undergoing single and two-level ACDF were discharged less than 15 hours after their surgeries (median time: 8 hours; range: 2-15 hours), and 4 patients (3.9%) were discharged after a 23-hour observation period following three-level ACDF. The overall complication rate in our outpatient series was 3.8% (n=4), including 1.9% (n=2) major and 1.9% (n=2) minor complications. The overall complication rate in the 633 patient meta-analysis derived comparison group was 0.95% (n=6). The difference between overall complication rates was not found to be significantly different (p = .12). The hardware-related complication rate in the meta-analysis comparison group was 0.5% (n=3), and was not found to be significantly different from our rate of 0% (p < or = 1).

CONCLUSION

Performing ACDF with instrumentation on an outpatient basis is feasible, and it is not associated with higher overall or hardware-related complication rates as compared with complication rates reported in the literature, suggesting that this procedure is safe to perform on an outpatient basis.

Back and neck pain in triathletes

OBJECT

As the sport of triathlon has continued to grow, increasing numbers of triathletes have presented in the neurosurgery clinics with various spinal disorders. This epidemiological study was undertaken to establish the lifetime incidence of neck and back pain, to gauge the prevalence of discogenic pain, and to identify risk factors among triathletes in the Boulder, Colorado, area.

METHODS

A live online questionnaire was developed that was used to collect information about physical characteristics, training habits, athletic status, number of races completed, and back pain among triathletes. The incidence of cervical and/or lumbar discogenic back pain was defined according to the duration of symptoms for the most recent pain episode. The lifetime incidence of low-back pain was 67.8%, with 23.7% of cases possibly being discogenic in origin. The number of triathlons in which the respondents had participated and the presence of previous sports-related injuries were predictive of low-back pain (p = 0.02 and p < 0.00001, respectively). The lifetime incidence of neck pain was 48.3%, with 21.4% of cases being consistent with intervertebral disc involvement. The number of previous sports-related injuries was predictive of neck pain (p < 0.00001), and a strong tendency toward neck pain was observed for athletes with more total years of participation in sports (p = 0.06).

CONCLUSIONS

The two main risk factors for long-term spinal problems include sports-related injuries and overuse. The study results definitely support the influence of both mechanisms for low-back pain. Neck pain was associated with an injury event, and a strong (although not statistically significant) tendency toward neck pain was observed in respondents with overuse injuries.

Three-dimensional computed tomographic analysis of the relationship between the arcuate eminence and the superior semicircular canal

OBJECTIVE

The location of the superior semicircular canal (SSC) is often determined intraoperatively based on its topographic association with the arcuate eminence (AE). This determination is not always possible because of the potential variability in the relationship between these two structures. The goal of this study was to describe the three-dimensional (3-D) relationship between the AE and SSC using 3-D computed tomography (CT) and to evaluate the utility of 3-D CT for preoperative planning for surgical approaches to the middle cranial fossa.

METHODS

We studied 11 patients (22 sides) radiographically using 0.8- to 1-mm thick reconstructed CT images. A standard set of structural relationships was measured between the AE, SSC, and other regional landmarks.

RESULTS

3-D CT clearly demonstrated the relationships between traditional landmarks along the petrous ridge and middle cranial fossa. The relationship between the arcuate eminence and SSC was found to be highly variable. The average distance between the tips of the two structures was found to be 5.7 mm (range, 2.7-10.4 mm).

CONCLUSIONS

There is significant variability in the relationship between the AE and the SSC. The AE is not a consistent or reliable landmark for identifying the precise position of the SSC. Detailed preoperative information regarding the relationship between the AE, SSC, and other bony landmarks can be easily and quickly assessed using 3-D CT.

Perioperative complications in transforaminal lumbar interbody fusion versus anterior-posterior reconstruction for lumbar disc degeneration and instability

OBJECTIVES

Multiple different approaches are used to treat lumbar degenerative disc disease and spinal instability. Both anterior-posterior (AP) reconstructive surgery and transforaminal lumbar interbody fusion (TLIF) provide a circumferential fusion and are considered reasonable surgical options. The purpose of this study was to quantitatively assess clinical parameters such as surgical blood loss, duration of the procedure, length of hospitalization, and complications for TLIF and AP reconstructive surgery for lumbar fusion.

METHODS

A retrospective analysis was completed on 167 consecutive cases performed between January 2002 and March 2004. TLIF surgical procedure was performed on 124 patients, including 73 minimally invasive and 51 open cases. AP surgery was performed on 43 patients. Patients were treated for painful degenerative disc disease, facet arthropathy, degenerative instability, and spinal stenosis.

RESULTS

The mean operative time for AP reconstruction was 455 minutes, for minimally invasive TLIF 255 minutes, and open TLIF 222 minutes. The mean blood loss for AP fusion surgery was 550 mL, for minimally invasive TLIF 231 mL, and open TLIF 424 mL. The mean hospitalization time for AP reconstruction was 7.2 days, for minimally invasive TLIF 3.1 days, and open TLIF 4.1 days. The total rate of complications was 76.7% for AP reconstruction, including 62.8% major and 13.9% minor complications. The minimally invasive TLIF patients group had the total 30.1% rate of complications, 21.9% of which were minor and 8.2% major complications. There were no major complications in the open TLIF patients group, with 35.3% minor complications.

CONCLUSIONS

AP lumbar interbody fusion surgery is associated with a more than two times higher complication rate, significantly increased blood loss, and longer operative and hospitalization times than both percutaneous and open TLIF for lumbar disc degeneration and instability.

Safety of transforaminal lumbar interbody fusion and intervertebral recombinant human bone morphogenetic protein-2

OBJECT

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is being increasingly used for spinal fusion. There are few data regarding its clinical safety, effectiveness, and clinical outcome when applied on an absorbable collagen sponge (ACS) in conjunction with allograft for transforaminal lumbar interbody fusion (TLIF).

METHODS

Seventy-four consecutive patients undergoing TLIF for degenerative disc disease were divided into five groups depending on whether the patient underwent a minimally invasive or open approach, as well as the number of spinal levels surgically treated. Surgery-related data, fusion results, complications, and clinical outcome were evaluated. The mean follow-up duration was 20.6 months (range 14-28 months). The radiographic fusion rate was 100% at 12 and 24 months after the surgery. No bone overgrowth or other complications related to BMP use were demonstrated.

CONCLUSIONS

Analysis of the results demonstrated that TLIF combined with a BMP-2-soaked ACS is a feasible, effective, and safe method to promote lumbar fusion. There were no significant intergroup differences in clinical outcome between patients who underwent open compared with minimally invasive procedures. Patient satisfaction rates, however, were higher in the minimally invasive procedure group. The efficacy of BMP-2 was not dependent on which approach was used or the number of spinal levels that were treated.

Thoracolumbar vertebral reconstruction after surgery for metastatic spinal tumors: long-term outcomes

Object

Metastatic spinal tumors continue to represent a major problem for patients and treating physicians. The purpose of this study was to assess quantitatively the functional outcome, quality of life, and survival rates of patients after major reconstructive spine surgery.

Methods

A prospective database was established and 58 patients were identified who had undergone thoracolum-bar vertebral reconstruction for metastatic spinal tumors between March 1993 and October 1999. Surgical indications included disabling pain (92%) and/or progressive neurological dysfunction (60%).

Forty-nine patients (85%) had clinical improvement in pain as determined based on the Oswestry pain scale (p < 0.05); 60% demonstrated improvement in their neurological status. The mean neurological improvement in Frankel grade was 1.2 (p < 0.05). The 12-month survival rate was 65%, and all patients who were ambulatory after surgery remained so until the time of death. Instrumentation failure requiring repeated operation occurred in two patients (3.5%), and in 12 patients (21%) local tumor recurrence necessitated repeated surgery. There were no cases of neurological deficit or death related to surgery.

Conclusions

Major anterior thoracolumbar vertebral reconstruction is an effective treatment for local tumor control. More importantly, the authors have demonstrated that surgical treatment can significantly improve the quality of life by improvement of pain control and maintenance of ambulation during the patient's remaining life span.

Utility of Computerized Isocentric Fluoroscopy for Minimally Invasive Spinal Surgical Techniques

OBJECTIVE

The purpose of this study was to prospectively evaluate the clinical utility and accuracy of intraoperative three-dimensional fluoroscopy as an adjunct for the placement of a complex spinal instrumentation.

METHODS

The Siemens Iso-C three-dimensional fluoroscopy unit in the combination with the Stealth Treon computer volumetric navigational system was used. A total of 279 spinal instrumentation screws or transpedicular cannulations were performed in 69 patients. Accuracy, operative time, and amount of fluoroscopy utilization time were assessed for transforaminal lumbar interbody fusion (TLIF) and kyphoplasty cases.

RESULTS

Only 4 percutaneous transpedicular lumbar screws out of 265 total (1.5%) were malpositioned. Average operative time for TLIF cases was 185 minutes (range 114-311 minutes) for one-level and 292.6 minutes (range 173-390 minutes) for two-level procedures. Biplanar fluoroscopy utilization time was 93 seconds (range 27-280 seconds) for one-level procedures and 216 seconds (range 80-388 seconds) for two-level procedures. Average surgery duration for kyphoplasty was 60 minutes (range 36-79 minutes) for one-level procedures and 68.5 minutes (range 65-75 minutes) for two-level cases. Biplanar fluoroscopy utilization time was 41.3 seconds per case (range 25-62 seconds).

CONCLUSIONS

Use of intraoperative three-dimensional fluoroscopy for image guidance in minimally invasive complex spinal instrumentation procedures is feasible and safe. This technique provides excellent visualization of three-dimensional relationships. This potentially results in improved accuracy of screw positioning and the ability to detect misplaced screws prior to wound closure. This technique also potentially results in a significant reduction in radiation exposure for both the patient and the staff.

CyberKnife radiosurgery for idiopathic trigeminal neuralgia

OBJECT

Gamma knife surgery is an accepted treatment option for trigeminal neuralgia (TN). The safety and efficacy of CyberKnife radiosurgery as a treatment option for TN, however, has not been established.

METHODS

Forty-one patients were treated between May 2002 and September 2004 for idiopathic TN at Stanford University and the Rocky Mountain CyberKnife Center. Patients with atypical pain, multiple sclerosis, or previous radiosurgical treatment or a follow-up duration of less than 6 months were excluded. Patients were evaluated for the level of pain control, response rate, time to pain relief, occurrence of hypesthesia, and time to pain recurrence with respect to the length of the nerve treated and the maximum and the minimum dose to the nerve margin. Thirty-eight patients (92.7%) experienced initial pain relief at a median of 7 days after treatment (range, 24 hours-4 months). Pain control was ranked as excellent in 36 patients (87.8%), moderate in two (4.9%), and three (7.3%) reported no change. Six (15.8%) of the 38 patients with initial relief experienced a recurrence of pain at a median of 6 months (range 2-8 months). Long-term response after a mean follow-up time of 11 months was found in 32 (78%) of 41. Twenty-one patients (51.2%) experienced numbness after treatment.

CONCLUSIONS

CyberKnife radiosurgery for TN has high rates of initial pain control and short latency to pain relief compared with those reported for other radiosurgery systems. The doses used for treatment were safe and effective. Higher prescribed doses were not associated with improvement in pain relief or recurrence rate. The hypesthesia rate was related to the length of the trigeminal nerve treated.

Intraoperative three-dimensional fluoroscopy-based computerized tomography guidance for percutaneous kyphoplasty

Object

Percutaneous kyphoplasty is an established method for the treatment of pathological vertebral compression fractures (VCFs). This procedure is usually performed with the aid of biplanar fluoroscopic image guidance. There are currently no published clinical studies in which the use of three-dimensional (3D) image guidance to facilitate this technique has been evaluated. The purpose of this study was to evaluate the efficacy of isocentric fluoroscopy-based navigation for the kyphoplasty procedure, with special reference to operating time and the amount of radiation exposure.

Methods

A prospective clinical study was performed in which 11 consecutive patients with painful pathological VCFs that did not respond to conservative treatment underwent the kyphoplasty procedure. During this procedure, cannulation of the pedicle and vertebral body was performed with the aid of isocentric 3D fluoroscopy visualization. Total operating time and intraoperative fluoroscopy time for this group was compared with a cohort of nine patients who underwent the procedure prior to the availability of isocentric fluoroscopy (only biplanar fluoroscopy was used). Possible complications such as cement extravasations were evaluated during the procedure and on postoperative computerized tomography scans.

The mean duration of surgery for the 3D isocentric fluoroscopic guidance group was 60 minutes (range 36–89 minutes) for one-level and 68.5 minutes (range 65–75 minutes) for two-level cases. Because of a learning curve with the equipment, the operating time for the initial cases was significantly longer than with the later ones. Even with the initial cases included, the mean operating time was shorter compared with the biplanar fluoroscopy-assisted procedures, which averaged 69.2 minutes (range 44–113 minutes) for one-level procedures. This difference was not statistically significant. The mean fluoroscopy exposure time was 41.3 seconds (range 25–62 seconds) in the isocentric fluoroscopy-assisted procedures, with an additional 40 seconds of fluoroscopy time used for the 3D fluoroscopy “spin,” compared with 293.2 seconds (range 180–400 seconds) in the biplanar fluoroscopy-assisted procedures. The difference was statistically significant (p = 0.02). All pedicles were accessed without difficulty and no complications were encountered in either group of patients.

Conclusions

The main advantage of isocentric fluoroscopy is the significant reduction in radiation exposure for the patient and surgical staff without an increase in the mean operating time. This technique is a significant advancement over biplanar fluoroscopy in this setting.

Endoscopic lateral transpsoas approach to the lumbar spine

STUDY DESIGN

A description of a novel surgical approach to the lumbar spine and a prospective evaluation of the early surgical outcomes.

OBJECTIVES

Describe the early postoperative results and the operative technique of a new, minimally invasive transpsoas approach for anterior fusion of the lumbar spine that minimizes the risk to large vessels and other critical structures.

SUMMARY OF BACKGROUND DATA

Standard anterior endoscopic approaches to the lumbar spine require mobilization of the great vessels and sympathetic plexus. Vascular injury and retrograde ejaculation are complications clearly associated with this approach. A retroperitoneal, transpsoas approach to the lumbar spine may reduce these risks.

METHODS

From 1996 to 2002, 21 patients (13 females, 8 males; mean age 50.0 years) underwent an endoscopic, retroperitoneal transpsoas approach for exposure of the lumbar spine. Surgical indications included discogenic pain in 14 patients, spinal instability at a level adjacent to a previous fusion in 3 patients, and progressive degenerative scoliosis in 4 patients. Data were reviewed to document the early postoperative results for this procedure. Illustrations were created to clearly describe this approach.

RESULTS

Average operative time for the single level cases was 149 minutes (range 120-170 minutes); blood loss was 150 cc (range 50-650); postoperative hospital stay was 4.1 days. At long-term follow-up, visual analogue scale scores had decreased an average of 5.9. Mean follow-up was 3.1 years (range 2 months-6.0 years). Six patients (30%) experienced paresthesias in the groin/thigh region. Five of these same patients also complained of groin/thigh pain (27%). Two patients had symptoms that lasted longer than 1 month. One patient was converted to a mini-open lateral approach. There were no vascular injuries.

CONCLUSIONS

Early results show the endoscopic lateral transpsoas approach to the lumbar spine to be a safe, minimally invasive method for anterior fusion of the first through the fourth lumbar vertebrae. Although there is a risk of groin/thigh numbness or pain, and these symptoms are mostly transient. This approach allows for exposure of the lumbar spine without mobilization of the great vessels or sympathetic plexus.

Comparison of revision rates following endoscopically versus nonendoscopically placed ventricular shunt catheters

BACKGROUND

Endoscopic placement of ventriculoperitoneal (VP) shunt catheters in pediatric patients has been increasingly used in an attempt to minimize the unacceptably high rates of revision. Although this procedure carries an increased expense, there is currently no evidence to support an improved long-term outcome. This paper compares the rates of revision following ventricular catheter placement for shunted hydrocephalus with and without the use of endoscopy.

METHODS

We retrospectively reviewed the records of all pediatric patients who had undergone shunt placement for hydrocephalus between April 1992 and February 1998. All shunts placed before March 1995 were performed without the endoscope; all subsequent shunts were placed endoscopically. The independent effect of endoscopic versus nonendoscopic shunt placement on subsequent shunt failure was analyzed via multivariate proportional hazards regression model. Multiple logistic regression analyses were used to determine the independent effect of endoscopic placement on subsequent etiology of failure (infection, proximal obstruction, distal malfunction) in the 511 failing shunts.

RESULTS

There were 447 pediatric patients who underwent a total of 965 shunt placements or revisions. Six hundred and five (63%) catheters were placed with the use of the endoscope. Three hundred and sixty (37.3%) were placed without the use of the endoscope. Neuroendoscopy did not independently affect the risk of subsequent shunt failure [Hazard Ratio (95% Confidence Interval) = 1.08 (0.84-1.41)]. Endoscopic placement independently decreased the odds [Odds Ratio (95% Confidence Interval) = 0.56 (0.32-0.93)] of proximal obstruction, increased the odds of distal malfunction [1.52 (1.02-2.72)], and was not associated with infection [1.42 (0.78-2.61)].

CONCLUSIONS

Endoscopic assisted ventricular catheter placement decreased the odds of proximal obstruction but failed to improve overall shunt survival in this 6 year experience.

MRI-guided stereotactic biopsy in the diagnosis of glioma: comparison of biopsy and surgical resection specimen

BACKGROUND

Although there has been a dramatic increase in the accessibility and utilization of high-resolution MRI techniques for the evaluation of brain tumors, there is currently only a single report comparing stereotactic brain biopsy specimen to subsequent resection specimen exclusively in the management of gliomas.

METHODS

The diagnoses in 43 cases of astrocytic brain tumors were derived using MRI-guided stereotactic biopsy followed by open resection of the lesion. The histologic diagnoses yielded by biopsy were compared with subsequent histologic diagnosis after open tumor resection. All biopsies and histologic diagnoses were made by the same surgeon and pathologist, respectively.

RESULTS

In 23 patients undergoing resection <60 days after biopsy, the biopsy diagnosis was consistent with resection diagnosis in 18 cases (79%) and led to the correct treatment in 22 cases (96%). Recurrent glioblastoma multiforme (GBM) was undergraded as anaplastic astrocytoma in 4 patients. GBM was misdiagnosed as radiation necrosis in 1 patient. MR-nonenhancing lesions [10/10 (100%)] yielded histology that correlated with subsequent craniotomy, while only 8/13 (61%) MR-enhancing lesions yielded histology that was consistent with that at craniotomy (p < 0.05). In 20 patients undergoing resection because of radiologic tumor progression (mean 7 months after biopsy), 6/6 (100%) biopsy diagnoses of a specific glioma grade correlated with resection diagnosis, while only 6/14 (43%) biopsy diagnoses of radiation effect correlated with resection diagnosis (p < 0.01).

CONCLUSION

MRI-guided stereotactic brain biopsy specimen accurately represents the grade of the larger glioma mass sufficiently to guide subsequent therapy. Enhancement on MR may be a negative prognostic indicator of biopsy accuracy.

MRI-guided frameless stereotactic percutaneous cordotomy

BACKGROUND

Use of intraoperative myelography as a radiologic guidance for percutaneous cervical cordotomy (PCC) has been superseded by more modern imaging. The only significant advancement in cordotomy techniques over the last 30 years has been CT-guided PCC. The goal of this study was to demonstrate the feasibility of an MRI-guided frameless technique in high cervical cordotomy.

METHODS

We describe 6 patients with intractable pain treated using a frameless, MRI-guided, stereotactic, PCC technique in combination with standard physiological localization procedures. Results were compared with those from 32 patients who underwent PCC in the last 5 years using physiological localizing techniques only.

RESULTS

Six patients (100%) who underwent the frameless technique had excellent pain relief postoperatively. Patients in the non-stereotactic group, on average, required a higher number of lesions (2.5 vs. 1.2, p < 0.005), and 7 (22%) of these patients had unsatisfactory pain relief following PCC (p = 0.21). Five patients in the non-stereotactic group had weakness postoperatively and 1 had changes in bladder function. Postoperative weakness occurred in 1 patient undergoing the frameless technique. At an average of 6 months of follow-up (range 5-11), excellent pain relief was achieved in 83% (5/6) of MRI frameless PCC patients and 55% (16/29) of standard PCC patients (p = 0.20).

CONCLUSIONS

Intraoperative frameless stereotaxy provides surgeons with accurate information that helps to guide the operative approach and precisely tailor the trajectory and depth of the electrode, potentially increasing the safety and efficacy of the operation.

Use of the peak troponin value to differentiate myocardial infarction from reversible neurogenic left ventricular dysfunction associated with aneurysmal subarachnoid hemorrhage

OBJECT

Differentiating myocardial infarction (MI) from reversible neurogenic left ventricular dysfunction (stunned myocardium [SM]) associated with aneurysmal subarachnoid hemorrhage (SAH) is critical for early surgical intervention. The authors hypothesized that the cardiac troponin (cTn) trend and/or echocardiogram could be used to differentiate between the two entities.

METHODS

A retrospective study was conducted for the period between 1995 and 2000. All patients included in the study met the following criteria: 1) no history of cardiac problems; 2) new onset of abnormal cardiac function (ejection fraction [EF] < 40% on echocardiograms); 3) serial cardiac markers (cTn and creatine kinase MB isoform [CK-MB]); 4) surgical intervention for their aneurysm; and 5) cardiac output monitoring either by repeated echocardiograms or invasive hemodynamic monitoring during the first 4 days post-SAH when the patients were euvolemic. Of the 350 patients with SAH, 10 (2.9%) had severe cardiac dysfunction. Of those 10, six were women and four were men. The patients' mean age was 53.5 years (range 29-75 years) and their SAH was classified as Hunt and Hess Grade III or IV. Aneurysm distribution was as follows: basilar artery tip (four); anterior communicating artery (two); middle cerebral artery (one); posterior communicating artery (two); and posterior inferior cerebellar artery (one). The mean EFonset was 33%. The changes on echocardiograms in these patients did not match the findings on electrocardiograms (EKGs). Within 4.5 days, dramatic improvement was seen in cardiac output (from 4.93 +/- 1.16 L/minute to 7.74 +/- 0.88 L/minute). Compared with historical controls in whom there were similar levels of left ventricular dysfunction after MI, there was no difference in peak CK-MB. A 10-fold difference, however, was noted in cTn values (0.22 +/- 0.25 ng/ml; control 2.8 ng/ml; p < 0.001).

CONCLUSIONS

The authors determined the following: 1) that the CK-MB trend does not allow differentiation between SM and MI; 2) that echocardiograms revealing significant inconsistencies with EKGs are indicative of SM; and 3) that cTn values less than 2.8 ng/ml in patients with EFs less than 40% are consistent with SM.

Successful aqueductal plasty and stenting for tectal plate tumor after failed third ventriculostomy: a case report

BACKGROUND

Tectal region tumors can lead to hydrocephalus secondary to aqueductal compression. Surgical options for these patients include extracranial cerebrospinal fluid (CSF) shunts, third ventriculostomy, and/or aqueductal plasty. In cases of third ventriculostomy failure, the accepted alternative is an extracranial CSF shunt. We report a patient in whom a repeat third ventriculostomy with aqueductal plasty and stenting was successful after a failed initial third ventriculostomy.

CASE PRESENTATION

A 12-year-old patient with hydrocephalus secondary to a tectal tumor presented with headaches and blurry vision. She had no focal neurologic findings. She underwent a third ventriculostomy. Five months after the procedure she had recurrence of her symptoms. Therefore, she underwent a secondary third ventriculostomy with aqueductal plasty and stenting. She has been symptom-free for 1 year.

CONCLUSION

Aqueductal plasty with stenting may be an alternative to CSF shunts in some patients with hydrocephalus because of aqueductal compression resulting from tectal tumors.

A new millenium for spinal cord regeneration: growth-associated genes

INTRODUCTION

Neurons surviving spinal cord injury undergo extensive reorganization that may result in the formation of functional synaptic contacts. Many neurons, however, fail to activate the necessary mechanisms for successful regeneration. In this review, we discuss the implications of growth cone genes that we have correlated with successful spinal cord axonal regeneration.

METHOD

Factors that inhibit regeneration, and activation of genes that promote it are discussed.

RESULTS/DISCUSSION

The early progress n understanding mechanisms that seem to promote or inhibit regeneration in the central nervous system may have significant clinical utility in the future.

Cerebrospinal fluid shunt survival and etiology of failures: a seven-year institutional experience

BACKGROUND

Innovations in shunt technology and neuroendoscopy have been increasingly applied to shunt management. However, the relative life span of shunts and the etiology of shunt failure have not been characterized recently.

METHODS

We reviewed the records of all shunting procedures at our institution between January 1992 and December 1998. Independent predictors of shunt failure were analyzed via multivariate Cox regression analysis in 836 shunting procedures. Independent predictors of the etiology of failure (infection, proximal obstruction, distal malfunction) were analyzed via multivariate logistic regression analysis in the 383 shunts which failed.

RESULTS

A total of 353 pediatric patients underwent 308 shunt placements and 528 revisions. The risk (hazard ratio; HR) of shunt failure decreased as a function of time in both primary placements and revised shunts. In failed shunts, the odds of infection decreased 4-fold per year of shunt function, while the odds of distal malfunction increased 1.45-fold per year. Increasing number of shunt revisions (HR 1.31, p < 0.05), decreasing patient age in years (HR 1.04, p < 0.001), gestational age <40 weeks (HR 2.15, p < 0.001) but not the etiology of hydrocephalus were associated with an increased risk of shunt failure. Revisions versus primary placements, Dandy-Walker cysts and gestational age <40 weeks were independently associated with proximal, distal and infectious causes of failure, respectively.

CONCLUSIONS

The long-term shunt revision rates observed here are similar to those reported over the past 2 decades. Shunt life span remains poorer in shunt revisions and in younger patients. Patient characteristics may suggest a specific risk and mechanism of failure, aiding in the long-term management of shunted hydrocephalus.

De novo cerebral arteriovenous malformation: case report

OBJECTIVE AND IMPORTANCE

Arteriovenous malformations (AVMs) are generally thought to have a congenital cause. This is the first report of an angiographically proven de novo cerebral AVM in an adult patient without previous vascular abnormality.

CLINICAL PRESENTATION

A 26-year-old African-American woman developed multiple cranial nerve deficits and ataxia over the course of a few days after a streptococcal throat infection. T2-weighted magnetic resonance imaging scans revealed a hyperintense signal in the midbrain with extension into the diencephalon. A cerebral angiogram performed at that time to exclude vasculitis revealed normal cerebral vasculature. The patient was treated with corticosteroids, and symptoms resolved. Subsequently, at the age of 32, this patient presented with a severe headache and emesis, but with no focal neurological deficit.

INTERVENTION

The patient's cranial computed tomographic and magnetic resonance imaging scans revealed a right posterior temporal intraparenchymal hemorrhage, and cerebral angiography revealed a new 3- by 2-cm AVM. The patient underwent microsurgical resection of the AVM and associated hematoma. Postoperative angiography revealed no evidence of residual AVM.

CONCLUSION

This study details the case of a woman who developed a de novo cerebral AVM during a 6-year period. This report challenges the conventional belief that all AVMs have a congenital cause.

Management of tumor bed cysts after chemotherapeutic wafer implantation. Report of four cases

Adjuvant use of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) wafers with surgical resection is becoming common for the treatment of malignant gliomas. Cyst formation in the tumor resection cavity is a recently described complication associated with the use of BCNU wafers. There is currently no report in which successful management of this complication without additional surgical intervention is described. The authors describe four patients in whom postoperative cysts developed in the tumor resection cavity after placement of BCNU wafers. These include a 38-year-old man with a left frontoparietal tumor, a 48-year-old man with a right frontal lobe tumor, a 78-year-old man with a left parietooccipital tumor, and a 61-year-old woman with a left frontotemporal tumor. Histopathological studies of biopsy samples revealed malignant glioma in each patient. All four patients had unremarkable perioperative courses, were discharged within 3 to 8 days of surgery, and subsequently returned with acute neurological deterioration. Follow-up magnetic resonance (MR) imaging demonstrated cyst formation with significant mass effect at the previous resection site. Three patients were treated with high-dose dexamethasone and returned to their neurological baseline over an 8-day period. The fourth patient improved after surgical drainage and biopsy sampling of the cyst, which revealed no evidence of infection or recurrent tumor, but again sought medical care 2 weeks later with cyst recurrence necessitating high-dose steroid therapy. On MR images at least a 30% reduction in cyst size was demonstrated in all four patients, each of whom remained clinically stable at 2, 6, 6, and 4 months of follow-up review. Neurosurgeons should be aware of the potential for postoperative cyst formation accompanied by clinically significant mass effect after BCNU wafer implantation, as well as the potential for successful nonsurgical management leading to clinical and radiological improvement.

Aggressive surgery and focal radiation in the management of meningiomas of the skull base: preservation of function with maintenance of local control

BACKGROUND

Recent study series have reported that post-operative external beam radiation therapy and stereotactic radiosurgery with the linear accelerator or gamma knife improves long-term local control of subtotally resected or recurrent meningiomas.

METHODS

Analysis of treatment results in 100 consecutive patients with skull base meningiomas managed by one surgeon with a median follow-up of five years. Treatment principles included observation for asymptomatic tumors; surgery for progressive or symptomatic tumors unless surgery was medically contraindicated or refused by the patient; to make surgery as aggressive as possible but with the goal of preserving full function of the patient; and to use radiosurgery or conformal fractionated radiation therapy if residual tumor was demonstrated. Preoperative, postoperative, and observational data were prospectively accumulated and stored in a large database system. Median follow up was 5 years with a range from 2 to 10 years.

FINDINGS

The most frequent presenting symptoms were headache (45%) and changes in vision (29%). Cranial nerve deficits (49%) and cerebellar signs (24%) were the most common physical findings. Seventy-two patients had surgical resection. Of these, 93% had greater than 50% resection and 47% had radiographically complete resection. There were no perioperative deaths and there were five surgical complications for a rate of 7%. Complications included hemiparesis (2.8%), new cranial nerve palsy (2.8%), and indolent osteomyelitis (1.4%). Fifteen patients had observation only; none of who progressed. Thirteen patients had radiation only, primarily because of patient preference or medical contraindications to surgery in the setting of substantial symptoms. There were no complications of this therapy. With a median five-year follow-up, only one patient (1%) demonstrated tumor progression using the treatment paradigm outlined here.

INTERPRETATION

These results demonstrate that skull base meningiomas which require treatment can be managed with a combination of aggressive surgery and conformal radiation with an acceptable functional status in 99% of cases.

Posterior atlantoaxial stabilization: new alternative to C1–2 transarticular screws

Object

Surgical treatment of atlantoaxial instability has evolved to include various posterior wiring techniques including Brooks, Gallie, and Sonntag fusions in which success rates range from 60 to 100%. The Magerl–Seemans technique in which C1–2 transarticular screws are placed results in fusion rates between 87 and 100%. This procedure is technically demanding and requires precise knowledge of the course of the vertebral arteries (VAs). The authors introduce a new C1–2 fixation procedure in which C-1 lateral mass and C-2 pedicle screws are placed that may have advantages over C1–2 transarticular screw constructs.

Methods

A standard posterior C1–2 exposure is obtained. Polyaxial C-2 pedicle screws and C-1 lateral mass screws are placed bilaterally. Rods are connected to the screws and secured using locking nuts. A cross-link is then placed. Fusion can be performed at the atlantoaxial joint by elevating the C-2 nerve root.

The technique for this procedure has been used in four cases of atlantoaxial instability at the author's institution. There have been no C-2 nerve root– or VA-related injuries. No cases of construct failure have been observed in the short-term follow up period.

Conclusions

Atlantoaxial lateral mass and axial pedicle screw fixation offers an alternative means of achieving atlantoaxial fusion. The technique is less demanding than that required for transarticular screw placement and may avoid the potential complication of VA injury. The cross-linked construct is theoretically stable in flexion, extension, and rotation. Laminectomy or fracture of the posterior elements does not preclude use of this fixation procedure.