Neurosurgery Blog

Neurosurgery 72:353–366, 2013

Stereoelectroencephalography (SEEG) methodology, originally developed by Talairach and Bancaud, is progressively gaining popularity for the presurgical invasive evaluation of drug-resistant epilepsies.

OBJECTIVE: To describe recent SEEG methodological implementations carried out in our center, to evaluate safety, and to analyze in vivo application accuracy in a consecutive series of 500 procedures with a total of 6496 implanted electrodes.

METHODS: Four hundred nineteen procedures were performed with the traditional 2- step surgical workflow, which was modified for the subsequent 81 procedures. The new workflow entailed acquisition of brain 3-dimensional angiography and magnetic resonance imaging in frameless and markerless conditions, advanced multimodal planning, and robot-assisted implantation. Quantitative analysis for in vivo entry point and target point localization error was performed on a sub–data set of 118 procedures (1567 electrodes).

RESULTS: The methodology allowed successful implantation in all cases. Major complication rate was 12 of 500 (2.4%), including 1 death for indirect morbidity. Median entry point localization error was 1.43 mm (interquartile range, 0.91-2.21 mm) with the traditional workflow and 0.78 mm (interquartile range, 0.49-1.08 mm) with the new one (P , 2.2 · 10216). Median target point localization errors were 2.69 mm (interquartile range, 1.89-3.67 mm) and 1.77 mm (interquartile range, 1.25-2.51 mm; P, 2.2 · 10216), respectively.

CONCLUSION: SEEG is a safe and accurate procedure for the invasive assessment of the epileptogenic zone. Traditional Talairach methodology, implemented by multimodal planning and robot-assisted surgery, allows direct electrical recording from superficial and deep-seated brain structures, providing essential information in the most complex cases of drug-resistant epilepsy.

J Neurosurg Spine 18:398–408, 2013

There have been significant advances in understanding the angioarchitecture of spinal dural arteriovenous fistulas (AVFs). However, the major intradural retrograde venous drainage system has not been investigated in detail, including the most proximal sites of intradural radiculomedullary veins as they connect to the dura mater, which are the final targets of interruption in both microsurgical and endovascular treatments.

Methods. Between April 1984 and March 2011, 27 patients with 28 AVFs were treated for spinal dural AVFs at the authors’ university hospital. The authors assessed vertebral levels of feeding arteries and dural AVFs by using conventional digital subtraction angiography. They also assessed 3D locations of the most proximal sites of intradural radiculomedullary veins and the 3D positional relationship between the major intradural retrograde venous drainage system and intradural neural structures, including the spinal cord, spinal nerves, and the artery of Adamkiewicz, by using operative video recordings plus 3D rotational angiography and/or 3D computer graphics. In addition, they statistically assessed the clinical results of 27 cases. Of these lesions, 23 were treated with open microsurgery and the rest were treated with endovascular methods.

Results. Feeding arteries consisted of T2–10 intercostal arteries with 19 lesions, T-12 subcostal arteries with 3 lesions, and L1–3 lumbar arteries with 6 lesions. The 3D locations of the targets of interruption (the most proximal sites of intradural radiculomedullary veins as they connect to the dura mater) were identified at the dorsolateral portion of the dura mater adjacent to dorsal roots in all 19 thoracic lesions, whereas they were identified at the ventrolateral portion of the dura mater adjacent to ventral roots in 7 (78%) of 9 cases of conus medullaris/lumbar lesions (p < 0.001). The major intradural retrograde venous drainage system was located dorsal to the spinal cord in all 19 thoracic lesions, whereas it was located ventral to the spinal cord in 4 (44%) of 9 cases of conus/lumbar lesions (p = 0.006). In 3 (11%) of 27 cases, AVFs had a common origin of the artery of Adamkiewicz. In 2 lumbar lesions, the artery of Adamkiewicz ascended very close to the vein because of its ventral location. Although all lesions were successfully obliterated without major complications and both gait and micturition status significantly improved (p = 0.005 and p = 0.015, respectively), conus/lumbar lesions needed careful differential diagnosis from ventral intradural perimedullary AVFs, because the ventral location of these lesions contradicted the Spetzler classification system.

Conclusions. The angioarchitecture of spinal dural AVFs in the thoracic region is strikingly different from that in conus/lumbar regions with regard to the intradural retrograde venous drainage system. One should keep in mind that spinal dural AVFs are not always dorsal types, especially in conus/lumbar regions.

J Neurosurg Pediatrics 11:227–241, 2013

The use of endoscopic endonasal surgery (EES) for skull base pathologies in the pediatric population presents unique challenges and has not been well described. The authors reviewed their experience with endoscopic endonasal approaches in pediatric skull base surgery to assess surgical outcomes and complications in the context of presenting patient demographics and pathologies.

Methods. A retrospective review of 133 pediatric patients who underwent EES at our institution from July 1999 to May 2011 was performed.

Results. A total of 171 EESs were performed for skull base tumors in 112 patients and bony lesions in 21. Eightyfive patients (63.9%) were male, and the mean age at the time of surgery was 12.7 years (range 2.3–18.0 years). Skull base tumors included angiofibromas (n = 24), craniopharyngiomas (n = 16), Rathke cleft cysts (n = 12), pituitary adenomas (n = 11), chordomas/chondrosarcomas (n = 10), dermoid/epidermoid tumors (n = 9), and 30 other pathologies. In total, 19 tumors were malignant (17.0%). Among patients with follow-up data, gross-total resection was achieved in 16 cases of angiofibromas (76.2%), 9 of craniopharyngiomas (56.2%), 8 of Rathke cleft cysts (72.7%), 7 of pituitary adenomas (70%), 5 of chordomas/chondrosarcomas (50%), 6 of dermoid/epidermoid tumors (85.7%), and 9 cases of other pathologies (31%). Fourteen patients received adjuvant radiotherapy, and 5 received chemotherapy. Sixteen patients (15.4%) showed tumor recurrence and underwent reoperation. Bony abnormalities included skull base defects (n = 12), basilar invagination (n = 4), optic nerve compression (n = 3) and trauma (n = 2); preexisting neurological dysfunction resolved in 12 patients (57.1%), improved in 7 (33.3%), and remained unchanged in 2 (9.5%). Overall, complications included CSF leak in 14 cases (10.5%), meningitis in 5 (3.8%), transient diabetes insipidus in 8 patients (6.0%), and permanent diabetes insipidus in 12 (9.0%). Five patients (3.8%) had transient and 3 (2.3%) had permanent cranial nerve palsies. The mean follow-up time was 22.7 months (range 1–122 months); 5 patients were lost to follow-up.

Conclusions. Endoscopic endonasal surgery has proved to be a safe and feasible approach for the management of a variety of pediatric skull base pathologies. When appropriately indicated, EES may achieve optimal outcomes in the pediatric population

Neurosurgery 72:353–366, 2013

Stereoelectroencephalography (SEEG) methodology, originally developed by Talairach and Bancaud, is progressively gaining popularity for the presurgical invasive evaluation of drug-resistant epilepsies.

OBJECTIVE: To describe recent SEEG methodological implementations carried out in our center, to evaluate safety, and to analyze in vivo application accuracy in a consecutive series of 500 procedures with a total of 6496 implanted electrodes.

METHODS: Four hundred nineteen procedures were performed with the traditional 2- step surgical workflow, which was modified for the subsequent 81 procedures. The new workflow entailed acquisition of brain 3-dimensional angiography and magnetic resonance imaging in frameless and markerless conditions, advanced multimodal planning, and robot-assisted implantation. Quantitative analysis for in vivo entry point and target point localization error was performed on a sub–data set of 118 procedures (1567 electrodes).

RESULTS: The methodology allowed successful implantation in all cases. Major complication rate was 12 of 500 (2.4%), including 1 death for indirect morbidity. Median entry point localization error was 1.43 mm (interquartile range, 0.91-2.21 mm) with the traditional workflow and 0.78 mm (interquartile range, 0.49-1.08 mm) with the new one (P < 2.2 · 10*16). Median target point localization errors were 2.69 mm (interquartile range, 1.89-3.67 mm) and 1.77 mm (interquartile range, 1.25-2.51 mm; P< 2.2 · 10*16), respectively.

CONCLUSION: SEEG is a safe and accurate procedure for the invasive assessment of the epileptogenic zone. Traditional Talairach methodology, implemented by multimodal planning and robot-assisted surgery, allows direct electrical recording from superficial and deep-seated brain structures, providing essential information in the most complex cases of drug-resistant epilepsy.

Neurosurgery 71:1096–1102, 2012

The lateral extracavitary approach (LECA) and costotransversectomy (CTE) are 2 dorsolateral approaches that avoid entrance into the pleural cavity and facilitate ventral decompression. The indications and outcomes of each of these approaches have not been fully defined in the literature.

OBJECTIVE: To assess the techniques, indications, and complications associated with the LECA and CTE approaches to the thoracic spine.

METHODS: A retrospective analysis was performed on all patients who underwent LECA and CTE between 2000 and 2009 at our institution.

RESULTS: A total of 54 patient charts were reviewed (19 LECA, 35 CTE). Indications for operation included disk herniation, trauma, tumor, osteomyelitis, and scoliosis/kyphosis. Osteomyelitis was treated significantly more often with LECA (47%) than with CTE (9%; P = .002). Mean blood loss was 2134 mL and 1556 mL (P = .3) in LECA and CTE, respectively, and hospital stay was 17.2 days for LECA and 9.8 days for CTE (P = .07). Thirteen LECA patients (68%) and 19 CTE patients (54%; P = 1.0) had preoperative or postoperative complications.

CONCLUSION: LECA was used more often to treat complex pathologies such as osteomyelitis and trended toward significance for more frequent use in extensive procedures involving 1- or 2-level corpectomies. As can be expected, CTE was associated with slightly less blood loss and a shorter hospital stay compared with the more extensive LECA operation. Adverse outcomes occurred with similar frequency for CTE and LECA.

Eur Spine J (2012) 21:2573–2579

Dynamic stabilization of the spine was developed as an alternative to rigid fusion in chronic back pain to reduce the risk of adjacent segment degeneration. Dynamic neutralization system (Dynesys, Zimmer CH) is one of the most popular systems available, but some midterm studies show revision rates as high as 30 %. Some late infectious complications in our patients prompted us to review them systematically. Propionibacterium recently has been shown to cause subtle infections of prosthetic material.

Materials and methods Here, we report on a consecutive series of 50 Dynesys implants. In a median follow-up of 51 months (range 0–91), we identified 12 infectious and 11 non-infectious complications necessitating reoperation or removal of the implant in 17 patients.

Results Material infections occurred after a median of 52 months (2–77) and were due to Propionibacterium alone (n = 4) or in combination (n = 3) in seven out of 11 patients. Clinical presentation combines new or increasing pain associated with signs of screw loosening on conventional X-rays; however, as many as 73.5 % of patients present some degree of screw loosening without being at all symptomatic of infection.

Conclusion The high rate of late infections with lowgrade germs and the frequency of screw loosening signs made us suspect a lack of integration at the bone-screw interface. Surgeons should be suspicious if the patient presents a combination of new or increasing pain and signs of screw loosening, and aggressive revision is recommended in these cases.

Neurosurgery 71:632–644, 2012 DOI: 10.1227/NEU.0b013e31825fd247

Stereotactic radiosurgery is an effective treatment modality for small arteriovenous malformations (AVMs) of the brain. For larger AVMs, the treatment dose is often lowered to reduce potential complications, but this decreases the likelihood of cure. One strategy is to divide large AVMs into smaller anatomic volumes and treat each volume separately.

OBJECTIVE: To prospectively assess the long-term efficacy and complications associated with staged-volume radiosurgical treatment of large, symptomatic AVMs.

METHODS: Eighteen patients with AVMs larger than 15 mL underwent prospective staged-volume radiosurgery over a 13-year period. The median AVM volume was 22.9 mL (range, 15.7-50 mL). Separate anatomic volumes were irradiated at 3- to 9-month intervals (median volume, 10.9 mL; range, 5.3-13.4 mL; median marginal dose, 15 Gy; range, 15-17 Gy). The AVM was divided into 2 volumes in 10 patients, 3 volumes in 5 patients, and 4 volumes in 3 patients. Seven patients underwent retreatment for residual disease.

RESULTS: Actuarial rates of complete angiographic occlusion were 29% and 89% at 5 and 10 years. Five patients (27.8%) had a hemorrhage after radiosurgery. Kaplan-Meier analysis of cumulative hemorrhage rates after treatment were 12%, 18%, 31%, and 31% at 2, 3, 5, and 10 years, respectively. One patient died after a hemorrhage (5.6%).

CONCLUSION: Staged-volume radiosurgery for AVMs larger than 15 mL is a viable treatment strategy. The long-term occlusion rate is high, whereas the radiation-related complication rate is low. Hemorrhage during the lag period remains the greatest source of morbidity and mortality.

J Neurosurg 117:265–275, 2012

In this paper the authors’ goal was to define the long-term benefits and risks of stereotactic radiosurgery (SRS) for patients with arteriovenous malformations (AVMs) who underwent prior embolization.

Methods. Between 1987 and 2006, the authors performed Gamma Knife surgery in 996 patients with brain AVMs; 120 patients underwent embolization followed by SRS. In this series, 64 patients (53%) had at least one prior hemorrhage. The median number of embolizations varied from 1 to 5. The median target volume was 6.6 cm3 (range 0.2–26.3 cm3). The median margin dose was 18 Gy (range 13.5–25 Gy).

Results. After embolization, 25 patients (21%) developed symptomatic neurological deficits. The overall rates of total obliteration documented by either angiography or MRI were 35%, 53%, 55%, and 59% at 3, 4, 5, and 10 years, respectively. Factors associated with a higher rate of AVM obliteration were smaller target volume, smaller maximum diameter, higher margin dose, timing of embolization during the most recent 10-year period (1997–2006), and lower Pollock-Flickinger score. Nine patients (8%) had a hemorrhage during the latency period, and 7 patients died of hemorrhage. The actuarial rates of AVM hemorrhage after SRS were 0.8%, 3.5%, 5.4%, 7.7%, and 7.7% at 1, 2, 3, 5, and 10 years, respectively. The overall annual hemorrhage rate was 2.7%. Factors associated with a higher risk of hemorrhage after SRS were a larger target volume and a larger number of prior hemorrhages. Permanent neurological deficits due to adverse radiation effects (AREs) developed in 3 patients (2.5%) after SRS, and 1 patient had delayed cyst formation 210 months after SRS. No patient died of AREs. A larger 12-Gy volume was associated with higher risk of symptomatic AREs. Using a case-control matched approach, the authors found that patients who underwent embolization prior to SRS had a lower rate of total obliteration (p = 0.028) than patients who had not undergone embolization.

Conclusions. In this 20-year experience, the authors found that prior embolization reduced the rate of total obliteration after SRS, and that the risks of hemorrhage during the latency period were not affected by prior embolization. For patients who underwent embolization to volumes smaller than 8 cm3, success was significantly improved. A margin dose of 18 Gy or more also improved success. In the future, the role of embolization after SRS should be explored.

J Neurosurg: Spine / July 17, 2012. DOI: 10.3171/2012.6.SPINE11915

Axial lumbar interbody fusion (AxiaLIF) is a minimally invasive presacral surgical technique that damages neither the anulus fibrosus nor the anterior or posterior longitudinal ligaments. The technique was initially designed and used for L5–S1 interbody fusions and recently was extended to 2-level fusions (L4–5 and L5–S1). Until now, only biomechanical and radiological studies have discussed the feasibility of this new indication, and no clinical study has been published. The purpose of this article is to report results and complications associated with 2-level presacral AxiaLIF with a minimum of 24 months of follow-up.

METHODS
In this prospective, nonrandomized, single-center study, 27 patients underwent presacral AxiaLIF surgery at the L4–5 and L5–S1 levels. Clinical outcomes were assessed using the visual analog scale for back and leg symptoms and the Oswestry Disability Index. Radiographic parameters, such as disc height, segmental lordosis, and bone fusion, were analyzed using radiographs and CT scans. Complications and revision surgeries were recorded as needed. The minimum follow-up was 24 months (up to 72 months).

RESULTS
There were no intraoperative complications. One major complication was observed: a patient developed septicemia that resolved after proper care. Clinical outcomes scores showed overall improvement in pain and physical function. During follow-up, the following complications were observed in the construct: screw breakage (14.8%), proximal/distal transsacral rod detachment (11.1%), radiolucency around the transsacral rod (52%), and cephalic rod migration (24%). Disc height gain was reported early after surgery, but at the 24-month follow-up the disc space was diminished in comparison with the preoperative status. Compared with preoperative values, the 24-month results showed loss of segmental lordosis. Only 22% of all treated levels were considered to have solid fusion at the 24-month radiological evaluation.

CONCLUSIONS
Patients undergoing presacral 2-level AxiaLIF experienced satisfactory short-term clinical outcomes; however, complications were commonly seen on imaging studies obtained 24 months postoperatively. Additional studies are required to better understand the 2-level indications for this technique.

Acta Neurochir DOI 10.1007/s00701-012-1321-5.

Microendoscopic discectomy (MED) is emerging as a minimally invasive alternative to conventional microsurgical discectomy (MSD). EASYGO! is a new system for spinal endoscopy that claims smooth transition from MSD to MED, with a reduced learning curve period. The aims of this study were to describe the complications that appeared during the learning curve period of MED and to compare their incidence with the rate and type of complications that occurred during a simultaneous non-randomised series of standard MSDs.

Methods Between July 2009 and December 2010, 138 patients underwent scheduled first-time discectomy in our institution, 37 using an MED approach and 101 by a conventional MSD. A MED learning curve was obtained by plotting every case with its respective operative time. Complications, length of hospital stay, need of further surgery and outcome were prospectively recorded in both groups.

Results The mean operative time was 66 min for the MSD group and 100 min for the MED group, although for the last 14 cases of the latter group the time was reduced. Curvefitting techniques showed that the inverse equation, ƒ(x)= 122.12/x+73.05, had the best correlation between case number and operative time. The learning curve was overcome after the 30th case. Complications occurred in 9.8 % of the MSD group and 8.1 % of the MED group (P=0.49). Average length of hospital stay was 2.36 days for the MED group and 3.36 days for the MSD group (P=0.01). The procedure successfully relieved patient symptoms in 68.63 % of the MSD group and 89.92 % of the MED group. No revision surgery was required in the MED group, but it was necessary in ten patients of the MSD group.

Conclusions Between 25 and 30 cases are needed to reach the learning curve’s asymptote of MED. Even during this initial learning period MED is a safe procedure, with comparable results to those obtained with conventional MSD and with a similar complication rate. The key points for reducing intraoperative complications are an adequate expertise in MSD, a precise selection of initial cases, a proper surgical planning and a careful technique, which are mandatory to avoid unnecessary neurological injury in an otherwise secure surgical approach.

J Neurosurg 116:54–65, 2012. DOI: 10.3171/2011.9.JNS11177

The object of this study was to define the long-term outcomes and risks of arteriovenous malformation (AVM) management using 2 or more stages of stereotactic radiosurgery (SRS) for symptomatic large-volume lesions unsuitable for surgery.

Methods. In 1992, the authors prospectively began to stage the treatment of anatomical components to deliver higher single doses to AVMs with a volume of more than 10 cm3. Forty-seven patients with such AVMs underwent volume-staged SRS. In this series, 18 patients (38%) had a prior hemorrhage and 21 patients (45%) underwent prior embolization. The median interval between the first-stage SRS and the second-stage SRS was 4.9 months (range 2.8–13.8 months). The median target volume was 11.5 cm3 (range 4.0–26 cm3) in the first-stage SRS and 9.5 cm3 in the second-stage SRS. The median margin dose was 16 Gy (range 13–18 Gy) for both stages.

Results. In 17 patients, AVM obliteration was confirmed after 2–4 SRS procedures at a median follow-up of 87 months (range 0.4–209 months). Five patients had near-total obliteration (volume reduction > 75% but residual AVM). The actuarial rates of total obliteration after 2-stage SRS were 7%, 20%, 28%, and 36% at 3, 4, 5, and 10 years, respectively. The 5-year total obliteration rate after the initial staged volumetric SRS with a margin dose of 17 Gy or more was 62% (p = 0.001). Sixteen patients underwent additional SRS at a median interval of 61 months (range 33–113 months) after the initial 2-stage SRS. The overall rates of total obliteration after staged and repeat SRS were 18%, 45%, and 56% at 5, 7, and 10 years, respectively. Ten patients sustained hemorrhage after staged SRS, and 5 of these patients died. Three of 16 patients who underwent repeat SRS sustained hemorrhage after the procedure and died. Based on Kaplan-Meier analysis (excluding the second hemorrhage in the patient who had 2 hemorrhages), the cumulative rates of AVM hemorrhage after SRS were 4.3%, 8.6%, 13.5%, and 36.0% at 1, 2, 5, and 10 years, respectively. This corresponded to annual hemorrhage risks of 4.3%, 2.3%, and 5.6% for Years 0–1, 1–5, and 5–10 after SRS. Multiple hemorrhages before SRS correlated with a significantly higher risk of hemorrhage after SRS. Symptomatic adverse radiation effects were detected in 13% of patients, but no patient died as a result of an adverse radiation effect. Delayed cyst formation did not occur in any patient after SRS.

Conclusions. Prospective volume-staged SRS for large AVMs unsuitable for surgery has potential benefit but often requires more than 2 procedures to complete the obliteration process. To have a reasonable chance of benefit, the minimum margin dose should be 17 Gy or greater, depending on the AVM location. In the future, prospective volumestaged SRS followed by embolization (to reduce flow, obliterate fistulas, and occlude associated aneurysms) may improve obliteration results and further reduce the risk of hemorrhage after SRS.

Neurosurgery 69:1255–1260, 2011 DOI: 10.1227/NEU.0b013e31822ba315

Patients with medically unresponsive trigeminal neuralgia (TN) who are >70 years of age often undergo operations that typically provide pain relief for <5 years despite having a life expectancy that can exceed 15 years.

OBJECTIVE: To review the safety and efficacy of posterior fossa exploration (PFE) for TN patients >70 years of age.

METHODS: From 1999 to 2009, 67 TN patients >70 years of age (median, 74 years) underwent a PFE. Thirty-seven patients (55%) had failed ≥1 prior surgeries (median, 2). Fifty-nine patients (88%) had a microvascular decompression, and 8 patients (12%) underwent a partial sensory rhizotomy. Follow-up (median, 40 months) was censored at the time of last contact (n = 51), additional surgery (n = 12), or death (n = 4).

RESULTS: Complete pain relief (no pain, no medications) was 87% at 1 year and 78% at 5 years. Facial pain outcomes did not correlate with patient age, sex, prior surgery, or pain duration. Postoperative complications were noted in 10 patients (15%) and included ataxia (10%), hearing loss (5%), trigeminal dysesthesias (5%), facial weakness (3%), aseptic meningitis (2%), and pulmonary embolus (2%). Factors associated with postoperative complications were prior PFE (P = .01) and neurovascular compression from a dolicoectatic basilar artery (P = .03).

CONCLUSION: Posterior fossa exploration is safe and effective for physiologically healthy TN patients .70 years of age. It should be deferred in older patients with TN secondary to a dolicoectatic basilar artery and patients who have persistent/recurrent pain after a previous PFE unless simpler procedures prove ineffective at controlling their facial pain.

Eur Spine J (2011) 20:1596–1606.DOI 10.1007/s00586-011-1873-8
Despite an increasing implantation rate of interspinous process distraction (IPD) devices in the treatment of intermittent neurogenic claudication (INC), definitive evidence on the clinical effectiveness of implants is lacking. The main objective of this review was to perform a meta-analysis of all systematic reviews, randomized clinical trials and prospective cohort series to quantify the effectiveness of IPDs and to evaluate the potential sideeffects.
Methods  Data from all studies prospectively describing clinical results based on validated outcome scales and reporting complications of treatment of patients with INC with IPD placement. We searched MEDLINE, EMBASE, Web of Science, Cochrane (CENTRAL), CINAHL, Academic Search Premier, Science Direct up to July 2010. Studies describing patients with INC caused by lumbar stenosis, reporting complication rate and reporting based on validated outcome scores, were eligible. Studies with only instrumented IPD results were excluded.
Results  Eleven studies eligible studies were identified. Two independently RCTs and eight prospective cohorts were available. In total 563 patients were treated with IPDs. All studies showed improvement in validated outcome scores after 6 weeks and 1 year. Pooled data based on the Zurich Claudication Questionnaire of the RCTs were more in favor of IPD treatment compared with conservative treatment (pooled estimate 23.2, SD 18.5–27.8). Statistical heterogeneity after pooled data was low (I-squared 0.0, p =  0.930). Overall complication rate was 7%.
Conclusion  As the evidence is relatively low and the costs are high, more thorough (cost-) effectiveness studies should be performed before worldwide implementation is introduced.

J Neurosurg 115:151–158, 2011. DOI: 10.3171/2011.1.JNS101492

Traditional ventriculoperitoneal (VP) shunt surgery involves insertion of the distal catheter by minilaparotomy. However, minilaparotomy may be a significant source of morbidity during shunt surgery. Laparoscopic insertion of the distal catheter is an alternative technique that may simplify and improve the safety of shunt surgery.

Methods. The authors performed a retrospective review of hospital records of all patients undergoing new VP shunt insertion at a tertiary care center between 2004 and 2009. Patient characteristics and outcomes were compared between patients undergoing open or laparoscopic insertion of the distal catheter. Independent variables in the analysis included age, sex, race, body mass index, surgical technique, previous VP shunt placement, previous abdominal procedures, American Society of Anesthesiology (ASA) score, and indication for shunt placement. Dependent variables included the occurrence of shunt failure, cause of shunt failure, complications, length of stay (LOS), LOS after shunt placement, estimated blood loss, and operative time.

Results. The authors identified 810 patients who met the inclusion criteria; open or laparoscopic distal catheter insertion was performed in 335 and 475 patients, respectively. There were no significant differences between the groups regarding age, race, ASA score, or indication for shunt placement. The most common indication was hydrocephalus due to subarachnoid hemorrhage, followed by tumor-associated hydrocephalus, normal pressure hydrocephalus (NPH), and hydrocephalus due to trauma. The incidence of shunt failure was not statistically different between cohorts, occurring in 20.0% of laparoscopic and 20.9% of open catheter placement cases (p = 0.791). With analysis of causes of shunt failure, shunt obstruction occurred significantly more often in the open surgery cohort (p = 0.012). In patients with a known cause shunt obstruction, distal obstruction occurred in 35.7% of the open cohort obstructions and 4.8% of the laparoscopic cohort obstructions (p = 0.014). The relative risk of distal obstruction in open cases compared with laparoscopic cases was 7.50. Infections occurred in 8.2% of laparoscopic cases compared with 6.6% of open cases (p = 0.419). Within the NPH subgroup, the laparoscopically treated patients had significantly more overdrainage (p = 0.040), whereas those in the open cohort experienced significantly more shunt obstructions (p = 0.034). Laparoscopically treated patients had shorter operative times (p < 0.0005), inpatient LOS (p < 0.001), and inpatient LOS after VP shunt placement (p = 0.01) as well as less blood loss (p = 0.058).

Conclusions. To our knowledge this is the largest reported comparison of distal VP shunt catheter insertion techniques. Compared with minilaparotomy, the laparoscopic approach was associated with decreased time in the operating room and a decreased LOS. Moreover, laparoscopy was associated with fewer distal shunt obstructions. Laparoscopic shunt surgery is a viable alternative to traditional shunt surgery.

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.

Neurosurgery 68:1259–1269, 2011 DOI: 10.1227/NEU.0b013e31820c0441

In order to weigh the risks of surgery against the presumed advantages, it is important to have specific knowledge about complication rates.

OBJECTIVE: To study the surgical mortality and rate of reoperations for hematomas and infections after intracranial surgery for brain tumors in a large, contemporary, single-institution consecutive series.

METHODS: All adult patients from a well-defined population of 2.7 million inhabitants who underwent craniotomies for intracranial tumors at Oslo University Hospital from 2003 to 2008 were included (n = 2630). The patients were identified from our prospectively collected database and their charts studied retrospectively. Follow-up was 100%.

RESULTS: The overall surgical mortality, defined as death within 30 days of surgery, was 2.3% (n = 60). The mortality rates for high- and low-grade gliomas, meningiomas, and metastases were 2.9%, 1.0%, 0.9%, and 4.5%, respectively. Age >60 (odds ratio 1.84, P< 0.05) and biopsy compared with resection (odds ratio 4.67, P <0.01) were significantly positively associated with increased surgical mortality. Hematomas accounted for 35% of the surgical mortality. Postoperative hematomas needing evacuation occurred in 2.1% (n = 54). Age >60 was significantly correlated to increased risk of postoperative hematomas (odds ratio 2.43, P < 0.001). A total of 39 patients (1.5%) were reoperated for postoperative infection. Meningiomas had an increased risk of infections compared with high-grade gliomas (odds ratio 4.61, P < 0.001).

CONCLUSION: The surgical mortality within 30 days of surgery was 2.3%, with age >60 and biopsy vs resection being the 2 factors significantly associated with increased mortality. Postoperative hematomas caused about one third of the surgical mortality.

Neurosurgery 68:491–495, 2011 DOI: 10.1227/NEU.0b013e3181ffa21c

Cerebrospinal fluid (CSF) diversionary methods are fraught with complications (eg, infection, obstruction, and CSF malabsorption at the distal site).

INTRODUCTION: The authors investigated the sternum, specifically the manubrium, as a potential CSF receptacle for patients with hydrocephalus.

METHODS: Five fresh adult human cadavers had the manubrium cannulated in a suprasternal location. Tap water was infused via a metal trocar for approximately 60 minutes. Additionally, morphometric examination of the manubrium from 40 adult human skeletons was performed. Next, 4 anesthetized rhesus monkeys underwent cannulation of the manubrium: 2 were infused with 50 mL of saline over approximately 1 hour, and 2 were infused by gravity drip of saline over 24 hours. Finally, 2 adult pigs underwent long-term ventriculosternal tube placement with analysis for function and potential development of osteomyelitis.

RESULTS: Thirty liters of water were injected into all cadaveric specimens without overflow or noticeable edema. No fluid accumulation was identified. The manubrium had a mean length, width, and thickness of 5.1 cm, 5.0 cm, and 1 cm, respectively. The animals that underwent infusion of 50 mL of saline and the animals that underwent gravity drip tolerated the procedure without vital sign changes or evidence of saline leakage into the pleural cavity. The 2 pigs did not show any vital sign changes, and, 2 weeks post procedure, they had no findings of osteomyelitis.

CONCLUSION: Based on our studies, the manubrium of the sternum appears to be an ideal location for the placement of the distal end of a CSF diversionary shunt when other anatomic receptacles are not an option. In vivo human studies are now required to verify our findings.

Spine 2010;35: S322–S330

Study Design. Prospective multicenter nonrandomized institutional review board-approved observational study of clinical and radiographic outcomes of the extreme lateral interbody fusion (XLIF) procedure in adult scoliosis.

Objective. Perioperative measures from this longitudinal study were compiled to identify the short-term results and complications of the procedure.

Summary of Background Data. The surgical treatment of adult scoliosis presents a treatment challenge. Neural decompression with combined anterior/posterior instrumented fusion is often performed. These procedures have been reported to carry a high risk of complication, particularly in the elderly patient population. Over the past decade, less invasive surgical approaches to neural decompression and fusion have been popularized and have recently been applied in the treatment of degenerative scoliosis. To date, there has been little published data evaluating these treatment approaches.

Methods. A total of 107 patients who underwent the XLIF procedure with or without supplemental posterior fusion for the treatment of degenerative scoliosis were prospectively studied. Intraoperative data collection included surgical procedural details, operative time, estimated blood loss, and surgical complications. Postoperative complications, length of hospital stay, and neurologic status were recorded. For this report, perioperative data (inclusive of outcomes through the 6-week postoperative clinic visit) were evaluated.

Results. In all, 107 patients (mean age, 68 years; range, 45–87) were treated with XLIF; 28% had at least 1 comorbidity. A mean of 4.4 levels (range, 1–9) were treated per patient. Supplemental pedicle screw fixation was used in 75.7% of patients, 5.6% had lateral fixation, and 18.7% had stand-alone XLIF. Mean operative time and blood loss were 178 minutes (58 minutes/level) and 50 to 100 mL. Mean hospital stay was 2.9 days (unstaged), 8.1 day (staged, 16.5%), 3.8 days overall. Five patients (4.7%) received a transfusion, 3 (2.8%) required intensive care unit admission, and 1 (0.9%) required rehabilitation services. Major complications occurred in 13 patients (12.1%): 2 (1.9%) medical, 12 (11.2%) surgical. Of procedures that involved only less invasive techniques (XLIF stand-alone or with percutaneous instrumentation), 9.0% had one or more major complications. In those with supplemental open posterior instrumentation, 20.7% had one or more major complication. Early reoperations (3) (all for deep wound infections) were associated with open posterior instrumentation procedures.

Conclusion. The morbidity in adult scoliosis surgery is minimized with less invasive techniques. The rate of major complications in this study (12.1%) compares favorably to that reported from other studies of surgery for degenerative deformity.

Neurosurgery 68:117–124, 2011 DOI: 10.1227/NEU.0b013e3181fcf14e

Unintended durotomy is a common complication of spinal surgery. However, the incidences reported in the literature vary widely and are based primarily on relatively small case numbers from a single surgeon or institution.

OBJECTIVE: To provide spine surgeons with a reliable incidence of unintended durotomy in spinal surgery and to assess various factors that may influence the risk of durotomy.

METHODS: We assessed 108.478 surgical cases prospectively submitted by members of the Scoliosis Research Society to a deidentified database from 2004 to 2007.

RESULTS: Unintended durotomy occurred in 1.6% (1745 of 108.478) of all cases. The incidence of unintended durotomy ranged from 1.1% to 1.9% on the basis of preoperative diagnosis, with the highest incidence among patients treated for kyphosis (1.9%) or spondylolisthesis (1.9%) and the lowest incidence among patients treated for scoliosis (1.1%). The most common indication for spine surgery was degenerative spinal disorder, and among these patients, there was a lower incidence of durotomy for cervical (1.0%) vs thoracic (2.2%; P = .01) or lumbar (2.1%, P < .001) cases. Scoliosis procedures were further characterized by etiology, with the highest incidence of durotomy in the degenerative subgroup (2.2% vs 1.1%; P < .001). Durotomy was more common in revision compared with primary surgery (2.2% vs 1.5%; P < .001) and was significantly more common among elderly (. 80 years of age) patients (2.2% vs 1.6%; P = .006). There was a significant association between unintended durotomy and development of a new neurological deficit (P < .001).

CONCLUSION: Unintended durotomy occurred in at least 1.6% of spinal surgeries, even among experienced surgeons. Our data provide general benchmarks of durotomy rates and serve as a basis for ongoing efforts to improve safety of care.

SPINE Volume 36, Number 1, pp 26–33

Study Design. Prospective analysis of 600 extreme lateral interbody fusion (XLIF) approach procedures for intraoperative and perioperative complications.

Objective. To delineate and describe complications in a large, prospective series of minimally invasive lateral lumbar fusion procedures (XLIF).

Summary of Background Data. While some small series of lateral lumbar fusion have discussed complications, no results from large studies have been reported.

Methods. A total of 600 patients were treated with a lateral approach to fusion (XLIF) for degenerative spinal conditions. Data were collected prospectively on all patients and analyzed for demographic, diagnostic, and hospitalization information to identify operative and early postoperative complications. Documented complication types and rates in this large series were compared with smaller prior reports on lateral approach fusions, as well as other minimally invasive (mini-anterior lumbar interbody fusion and minimally invasive surgical [MIS] transforaminal lumbar interbody fusion) and more traditional fusion approaches (posterior intertransverse fusion, anterior lumbar interbody fusion, posterior lumbar interbody fusion, transforaminal lumbar interbody fusion).

Results. Seven hundred forty-one levels were treated, 80.8% single level, 15.0% 2 level, 4.0% 3 level, 0.2% 4 level; 59.3%, including the L4 to L5 levels. A total of 99.2% included supplemental internal fi xation; 83.2% included pedicle screw fi xation (predominantly unilateral). Hemoglobin change from pre- to postoperation averaged 1.38. Hospital stay averaged 1.21 days. The overall incidence of perioperative complications (intraoperation and out to 6 weeks postoperation) was 6.2%: 9 (1.5%) in-hospital surgery-related events, 17 (2.8%) in-hospital medical events, 6 (1.0%) out-of-hospital surgery-related events, and 5 (0.8%) out-of-hospital medical events. There were no wound infections, no vascular injuries, no intraoperative visceral injuries, and 4 (0.7%) transient postoperative neurologic defi cits. Eleven events (1.8%) resulted in additional procedures/reoperation.

Conclusions. Compared with traditional open approaches, the MIS lateral approach to fusion by using the XLIF technique resulted in a lower incidence of infection, visceral and neurologic injury, and transfusion as well as markedly shorter hospitalization. Complications in MIS XLIF compare favorably with those from other MIS fusion procedures; duration of hospitalization is shorter than with any previously reported technique.