Neurosurgery Blog

J Neurosurg Spine 16:37–43, 2012. DOI: 10.3171/2011.9.SPINE11283

Present attempts to control health care costs focus on reducing the incidence of complications and hospital-acquired conditions (HACs). One approach uses restriction or elimination of hospital payments for HACs. Present approaches assume that all HACs are created equal and that payment restrictions should be applied uniformly. Patient factors, and especially patient comorbidities, likely impact complication incidence. The relationship of patient comorbidities and complication incidence in spine surgery has not been prospectively reported.

METHODS: The authors conducted a prospective assessment of complications in spine surgery during a 6-month period; an independent auditor and a validated definition of perioperative complications were used. Initial demographics captured relevant patient comorbidities. The authors constructed a model of relative risk assessment based on the presence of a variety of comorbidities. They examined the impact of specific comorbidities and the cumulative effect of multiple comorbidities on complication incidence.

RESULTS: Two hundred forty-nine patients undergoing 259 procedures at a tertiary care facility were evaluated during the 6-month duration of the study. Eighty percent of the patients underwent fusion procedures. One hundred thirty patients (52.2%) experienced at least 1 complication, with major complications occurring in 21.4% and minor complications in 46.4% of the cohort. Major complications doubled the median duration of hospital stay, from 6 to 12 days in cervical spine patients and from 7 to 14 days in thoracolumbar spine patients. At least 1 comorbid condition was present in 86% of the patients. An increasing number of comorbidities strongly correlated with increased risk of major, minor, and any complications (p = 0.017, p < 0.0001, and p < 0.0001, respectively). Patient factors correlating with increased risk of specific complications included systemic malignancy and cardiac conditions other than hypertension.

CONCLUSIONS: Comorbidities significantly increase the risk of perioperative complications. An increasing number of comorbidities in an individual patient significantly increases the risk of a perioperative adverse event. Patient factors significantly impact the relative risk of HACs and perioperative complications.

J Neurosurg Spine 16:44–50, 2012. DOI: 10.3171/2011.9.SPINE11373

Since its original description in 1982, transforaminal lumbar interbody fusion (TLIF) has grown in popularity as a means for achieving circumferential fusion. The authors sought to define the perioperative complication rates of the TLIF procedure at a large academic medical center.

Methods. For all eligible patients from a consecutive series of 531 TLIF procedures, the institution’s complication database and the medical record were reviewed to identify complications. Medical, nonprocedure-related complications such as myocardial infarction and pulmonary embolism were excluded due to inconsistency in the recording of these complications in the database. Rates were calculated for each type of complication, and subgroup analysis was performed to investigate the effect of previous lumbar surgery, and of multilevel versus single-level interbody fusion on complication rates. Odds ratios were calculated and evaluated using chi-square analysis.

Results. Five hundred thirty-one patients underwent a TLIF procedure during the study period. Two hundred forty-four patients (46%) had undergone a previous lumbar operation. Interbody fusion was performed at 1 level in 317 patients, at 2 levels in 188 patients, at 3 levels in 24 patients, and at 4 levels in 2 patients. One hundred thirty-five patients (25.4%) had at least one procedure-related complication. The most common complications were durotomy (14.3% of patients) and infection (3.8% of patients). Symptomatic screw misplacement (2.1% of patients) and interbody cage migration (1.8% of patients) were less common complications. The overall complication rate was greater in those patients who had undergone a previous operation (OR 1.75, 95% CI 1.18–2.59; p < 0.01) and in those who had multilevel surgery (OR 1.54, 95 % CI 1.04–2.28; p = 0.03), and the incidence of durotomy was higher in patients who had a previous operation (OR 1.75, 95% CI 1.07–2.87; p = 0.03). These differences were statistically significant. Durotomy also occurred more frequently in patients who had multilevel interbody fusion (OR 1.49, 95% CI 0.92–2.43; p = 0.13). A trend toward higher infection rates in those patients who underwent multilevel interbody fusion was observed (OR 1.5, 95% CI 0.62–3.68; p = 0.49), but this was not statistically significant. Infection rates did not differ between revision and first-time surgeries.

Conclusions. Transforaminal lumbar interbody fusion has gained widespread popularity as a procedure for achieving arthrodesis in the lumbar spine. Complications occurred more often in patients undergoing revision surgery or multilevel interbody fusion. Durotomy and infection were the most common complications in this series.

Acta Neurochir (2012) 154:33–41. DOI 10.1007/s00701-011-1209-9

Epidemiological studies indicate a link between low-dose irradiation (<10,000 mGy) to the head and the local occurrence of tumors after decades of delay. Comparable radiation doses can be reached during neuroendovascular procedures (NEP), but the incidence of similar exposures has not been completely delineated. We compared the levels of radiation to the head measured during NEP to those reported for patients developing radiation-induced cancers.

Methods In our prospective study we determined the cumulative maximum entrance skin doses (MESD) and the incidence of epilation in 107 consecutive patients submitted to NEP between 2003 and 2007. We also extensively searched the literature and compared our results with the data we found.

Results The cumulative MESD due to NEP was above 3,000 mGy (range 3,101–5,421 mGy) in 18 patients. In 22 we observed partial epilation within 10 weeks from the initial NEP. Sixty cases of epilation after NEP have been previously reported in the literature. The average of the reported MESD was 4,241 mGy (range 2,000–6,640 mGy).

Conclusion Physical dosimetry and the incidence of partial epilation indicate that about one fifth of the patients submitted to NEP received radiation doses comparable to those linked to the occurrence of tumors. The potential risks of developing tumors after a long delay, when compared to the immediate benefits of endovascular treatment of aneurysm and arteriovenous malformations (AVM) of the brain, do not counterindicate NEP, but increased awareness of the risk should help physicians and patients to make a fully informed decision when other treatments are available.

J Neurosurg 115:1169–1174, 2011. DOI: 10.3171/2011.7.JNS11536

Seizures are the most common presenting symptom of supratentorial cerebral cavernous malformations (CCMs) and progress to medically refractory epilepsy in 40% of patients. Predictors of seizure freedom in the resection of CCMs are incompletely understood.

Methods. The authors systematically reviewed the published literature on seizure freedom following the resection of supratentorial CCMs in patients presenting with seizures. Seizure outcomes were stratified across 12 potential prognostic variables. A total of 1226 patients with supratentorial CCMs causing seizures were identified across 31 predominantly retrospective studies; 361 patients had medically refractory epilepsy.

Results. Seventy-five percent of the patients were seizure free after microsurgical lesion removal, whereas 25% continued to have seizures. All patients had had preoperative seizures and > 6 months of postoperative follow-up. Modifiable predictors of postoperative seizure freedom included gross-total resection (OR 36.6, 95% CI 8.5–157.5) and surgery within 1 year of symptom onset (OR 1.83, 95% CI 1.30–2.58). Additional prognostic indicators of a favorable outcome were a CCM size < 1.5 cm (OR 15.4, 95% CI 5.2–45.4), the absence of multiple CCMs (OR 2.02, 95% CI 1.13–3.60), medically controlled seizures (OR 2.38, 95% CI 1.29–4.39), and the lack of secondarily generalized seizures (OR 3.33, 95% CI 2.09–5.30). Other factors, including extended resection of the hemosiderin ring, were not significantly predictive.

Conclusions. In the surgical treatment of supratentorial CCMs, gross-total resection and early operative intervention may improve seizure outcome. While surgery should not be considered the first-line treatment for CCM-related epilepsy, it is important to understand the variables associated with seizure freedom in CCM resection given the considerable morbidity and diminished quality of life associated with epilepsy.

J Neurosurg Pediatrics 8:539–599, 2011.DOI: 10.3171/2011.9.PEDS11192

Detailed costs to individuals with hydrocephalus and their families as well as to third-party payers have not been previously described. The purpose of this study was to determine the primary caregiver out-of-pocket expenses and the third-party payer reimbursement rate associated with a shunt failure episode.

Methods. A retrospective study of children born between 2000 and 2005 who underwent initial ventriculoperitoneal (VP) shunt placement and who subsequently experienced a shunt failure requiring surgical intervention within 2 years of their initial shunt placement was conducted. Institutional reimbursement and demographic data from Children’s Hospital of Alabama (CHA) were augmented with a caregiver survey of any out-of pocket expenses encountered during the shunt failure episode. Institutional reimbursements and caregiver out-of-pocket expenses were then combined to provide the cost for a shunt failure episode at CHA.

Results. For shunt failures, the median reimbursement total was $5008 (interquartile range [IQR] $2068– $17,984), the median caregiver out-of-pocket expenses was $419 (IQR $251–$1112), and the median total cost was $5411 (IQR $2428–$18,582). Private insurance reimbursed at a median rate of $5074 (IQR $2170–$14,852) compared with public insurance, which reimbursed at a median rate of $4800 (IQR $1876–$19,395). Caregivers with private insurance reported a median $963 (IQR $322–$1741) for out-of-pocket expenses, whereas caregivers with public insurance reported a median $391 (IQR $241–$554) for out-of-pocket expenses (p = 0.017).

Conclusions. This study confirmed that private insurance reimbursed at a higher rate, and that although patients had a shorter length of stay as compared with those with public insurance, their out-of-pocket expenses associated with a shunt failure episode were greater. However, it could not be determined if the significant difference in outof- pocket expenses between those with private and those with public insurance was due directly to the cost of shunt failure. This model does not take into consideration community resources and services available to those with public insurance. These resources and services could offset the out-of-pocket burden, and therefore should be considered in future cost models.

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.

J Neurosurg 115:1047–1052, 2011. DOI: 10.3171/2011.5.JNS101396

In recent years, the authors have noticed a growing number of programmable valve defects at their institution. Therefore, they conducted this study to evaluate the increased incidence of malfunctioning valves.

Methods. They investigated all revisions that had been performed at their institution between 1994 and 2010 for dislodgement of the stator of a standard Medos Hakim programmable valve with a prechamber.

Results. Fifteen valves were removed because of dislodged stators. The valves had been implanted between May 16, 1993, and December 27, 2002, and were explanted between February 19, 2006, and January 22, 2010. Thus, the valves had been in place for a mean period of 11 years (median 11 years, range 7–14 years). The percentage of dislodged stators was almost 3% (15 of 546 valves). Particularly noteworthy is that all malfunctioning valves were found in children who had been younger than 1 year of age at the time of implantation.

Conclusions. Medos Hakim programmable valve malfunctions are rare events but should receive careful attention. When the pressure setting cannot be adjusted, a malfunction should always be suspected and radiographic imaging should be performed to assess the valve. Stator dislodgement is the most serious form of valve adjustment failure.

Neurosurgery 69:774–781, 2011 DOI: 10.1227/NEU.0b013e31821ffa9e

Ventriculoperitoneal shunting is the most widely used neurosurgical procedure for the management of hydrocephalus.

OBJECTIVE: To evaluate our long-term single-institution experience in the management of adult hydrocephalus patients with ventriculoperitoneal shunts.

METHODS: Adult patients who underwent ventriculoperitoneal shunt placement for hydrocephalus from October 1990 to October 2009 were included. Medical charts, operative reports, imaging studies, and clinical follow-up evaluations were reviewed and analyzed retrospectively for clinical outcome in adult hydrocephalus patients.

RESULTS: A total of 683 adult patients were included in the study. The most common etiologies of hydrocephalus include idiopathic (29%), tumors and cysts (20%), postcraniotomy (13%), and subarachnoid hemorrhage (13%). The overall shunt failure rate was 32%, and the majority (74%) of shunt revisions occurred within the first 6 months. The median time to first shunt revision was 9.31 months. Etiology of hydrocephalus showed a significant impact on the incidence of shunt revision/failure and on the median time to shunt revision. Similarly, the type of hydrocephalus had a significant effect on the incidence of shunt failure and the median time to shunt revision.

CONCLUSION: A large proportion of patients (32%) experience shunt failure after shunt placement for hydrocephalus. Although the overall incidence of shunt revision was comparable to previously reported studies, the fact that a large proportion of adult populations with shunt placement experience shunt failure is a concern.

Neurosurgery 69:369–375, 2011 DOI: 10.1227/NEU.0b013e31821bc49c

The Neuroform Stent has facilitated the endovascular treatment of wide-necked cerebral aneurysms. It is unknown which factors pose risks of thromboembolic events after stent placement.

OBJECTIVE: This series is the largest single-center study reporting on the incidence of and factors influencing thromboembolic complications after Neuroform stent placement.

METHODS: A total of 235 patients were treated with 274 Neuroform stents. The thromboembolic event rate was determined by imaging or clinical evidence of cerebrovascular accident within 90 days of stent placement; for patients with incomplete follow-up through chart review, telephone interviews were conducted. Analyses were performed to investigate patient factors that may be associated with stroke.

RESULTS: Most aneurysms were unruptured; 30 patients (12.8%) presented with acute subarachnoid hemorrhage. Twelve patients of the 224 with follow-up (5.4%, 95% confidence interval: 2.4%-8.3%) demonstrated imaging or clinical evidence of a new thromboembolic event within 90 days of stent placement. There was a 3.1% thromboembolic rate for unruptured aneurysms and a 20% rate in patients with subarachnoid bleed. Hemorrhage was significantly associated with having a thromboembolic event (P = .002). There was a trend toward an increased thromboembolic event rate for patients with hypertension (P = .07). Larger stent caliber was significantly associated with a decreased thromboembolic event rate (P = .032).

CONCLUSION: Our results suggest that the thromboembolic event rate associated with Neuroform stent use is low in unruptured aneurysms. In ruptured aneurysms, the complication rate is high, possibly partly related to restricted use of antiplatelet therapy. Stent size and hypertension may be associated with the risk of stroke, but additional studies are needed to confirm their significance.

KEY WORDS: Cerebral aneurysms, Neuroform stent, Stent-assisted aneurysm coiling, Stent thrombosis, Thromboembolic complications

J Neurosurg 115:202–209, 2011. DOI: 10.3171/2011.4.JNS101924

Microvascular decompression (MVD) offers an effective and durable treatment for patients suffering from trigeminal neuralgia (TN). Because the disorder has a tendency to occur in older persons, the risks of surgical treatment in the elderly have been a topic of recent interest. To date, evidence derived from several small retrospective and a single prospective case series has suggested that age does not increase the complication rate associated with surgery. Using a large national database, the authors aimed to study the impact of age on in-hospital complications following MVD for TN.

Methods. Using the Nationwide Inpatient Sample (NIS) for the 10-year period from 1999 to 2008, the authors selected all patients who underwent MVD for TN. The primary outcome of interest was the in-hospital mortality rate. Secondary outcomes of interest were cardiac, pulmonary, thromboembolic, cerebrovascular, and wound complications as well as the duration of hospital stay, total hospital charges, and discharge location. An elderly cohort of patients was first defined as those 65 years of age and older and then redefined as those 75 years and older.

Results. A total of 3273 patients who underwent MVD for TN were identified, having a median age of 57 years. Within this sample, 31.5% were 65 years and older and 10.7% were 75 years and older. The in-hospital mortality rate was 0.68% for patients 65 years or older (p = 0.0087) and 1.16% for those 75 years or older (p = 0.0026). In patients younger than 65 years, the in-hospital mortality rate was 0.13% (3 deaths among 2241 patients). As analyzed using the chi-square test (for both 65 and 75 years as the age cutoff) and the Pearson rank correlation coefficient, the risk of cardiac, pulmonary, thromboembolic, and cerebrovascular complications was higher in older patients (that is, those 65 and older and those 75 and older), but the risks of wound complications and CNS infection were not. The risk of any in-hospital complication occurring in a patient 65 years and older was 7.36% (p < 0.0001) and 10.0% in those 75 years and older (p < 0.0001). There was no difference in the total hospital charges associated with age. The duration of the hospital stay was longer in older patients, and the likelihood of discharge home was lower in older patients.

Conclusions. Microvascular decompression for TN in the elderly population remains a reasonable surgical option. However, based on data from a large national database, authors of the present study suggest that complications do tend to gradually increase in tandem with an advanced age. While age does not act as a risk factor in isolation, it may serve as a convenient surrogate for complication rates. The authors hope that this information can be of use in guiding older patients through decisions for the surgical treatment of TN.

Neurosurgery 69:255–260, 2011 DOI: 10.1227/NEU.0b013e31821a45ba

Ventriculostomy placement is an important diagnostic and therapeutic tool for neurosurgeons. Multiple authors have presented retrospective series of patients evaluating periprocedure hemorrhage.

OBJECTIVE: We performed a meta-analysis of existing studies to determine a more accurate rate of hemorrhage.

METHODS: A MEDLINE and PubMed search was performed to find all studies of 25 or more patients conducted since 1970 that found a hemorrhagic complication rate from placement of a ventriculostomy. Studies in which a non-neurosurgeon placed the ventriculostomy and studies involving premature infants were excluded.

RESULTS: Sixteen studies were used to obtain data from 2428 ventriculostomy procedures. Hemorrhage was found after 203 procedures, and 52 of these hemorrhages were deemed significant by the authors. The cumulative rate of hemorrhage was 7.0% (95% confidence interval: 4.5%-9.4%), with P , .05. The cumulative rate of significant hemorrhage was 0.8% (95% confidence interval: 0.2%-1.4%) with P , .05.

CONCLUSION: Based on our meta-analysis, the overall hemorrhagic complication rate from ventriculostomy placement by neurosurgeons is approximately 7%. The rate of significant hemorrhage from ventriculostomy placement is approximately 0.8%. Further prospective studies are warranted to better address this question.

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

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

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

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

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

J Neurosurg Pediatrics 8:177–183, 2011. DOI: 10.3171/2011.5.PEDS10362

Posterior fossa decompression with duraplasty for Chiari malformation Type I (CM-I) is a common pediatric neurosurgery procedure. Published series report a complication rate ranging from 3% to 40% for this procedure. Historically, many dural substitutes have been used, including bovine grafts, human cadaveric pericardium, synthetic dura, and autologous pericranium. The authors hypothesized that a recently observed increase in complications was dependent on the graft used.

Methods. Between January 2004 and January 2008, 114 consecutive patients ≤ 18 years old underwent primary CM-I decompression using duraplasty. Records were retrospectively reviewed for short- and intermediate-term complications and operative technique, focusing on the choice of duraplasty graft with or without application of a tissue sealant.

Results. The average age of the patients was 8.6 years. The dural graft used was variable: 15 were treated with cadaveric pericardium, 12 with Durepair, and 87 with EnDura. Tisseel was used in 75 patients, DuraSeal in 12, and no tissue sealant was used in 27 patients. The overall complication rate was 21.1%. The most common complications included aseptic meningitis, symptomatic pseudomeningocele, or a CSF leak requiring reoperation. The overall complication rates were as follows: cadaveric pericardium 26.7%, Durepair 41.7%, and EnDura 17.2%; reoperation rates were 13%, 25%, and 8.1%, respectively. Prior to adopting a different graft product, the overall complication rate was 18.1%; following the change the rate increased to 35%. Complication rates for tissue sealants were 14.8% for no sealant, 18.7% for Tisseel, and 50% for DuraSeal. Nine patients were treated with the combination of Durepair and DuraSeal and this subgroup had a 56% complication rate.

Conclusions. Complication rates after CM-I decompression may be dependent on the dural graft with or without the addition of tissue sealant. The complication rate at the authors’ institution approximately doubled following the adoption of a different graft product. Tissue sealants used in combination with a dural substitute to augment a duraplasty may increase the risk of aseptic meningitis and/or CSF leak. The mechanism of the apparent increased inflammation with this combination remains under investigation.

Neurosurgery 69:294–300, 2011 DOI: 10.1227/NEU.0b013e318214abda

Deep brain stimulation (DBS) at the subthalamic nucleus (STN) is an effective treatment for the motor manifestations of advanced medically refractory Parkinson disease. Because of the medial location of the target, surgical trajectories to the STN may violate the ipsilateral lateral ventricle.

OBJECTIVE: To determine whether violating the ventricle during STN DBS surgery is associated with postoperative confusion.

METHODS: A retrospective chart review of all STN implantation procedures for Parkinson disease performed by 1 surgeon between January 2005 and September 2008 was performed. Postoperative magnetic resonance imaging was performed in all cases, and each scan was reviewed for evidence of ventricular wall violation. All charts were reviewed for postoperative confusion and/or increased length of hospital stay.

RESULTS: A total of 145 leads were implanted in 81 patients over 102 admissions. Fortythree patients underwent contemporaneous bilateral lead implantation; 23 underwent unilateral implantation; and 18 underwent staged bilateral implantation. The cases of 8 patients were complicated by postoperative confusion and increased length of stay. Sixteen magnetic resonance imaging scans demonstrated evidence of ventricular wall violation including all 8 patients with postoperative confusion. The relative risk of having postoperative confusion after traversing the ventricle is 87 (P , .001).

CONCLUSION: Violating the ventricular system during STN DBS surgery correlated significantly with postoperative altered mental status and subsequent increased length of hospital stay. This finding may explain why cognitive complications are observed more frequently in Parkinson disease patients undergoing DBS at the STN compared with the internal globus pallidus.

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

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

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

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

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

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

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

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

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

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 68:897–902, 2011 DOI: 10.1227/NEU.0b013e3182098bfa

The number of spine operations performed in the elderly population is rising.

OBJECTIVE: To identify and describe perioperative and postoperative complications in patients 70 years and older who have undergone minimally invasive lumbar interbody spine fusion.

METHODS: A retrospective analysis was performed on 66 consecutive patients aged 70 years or older who underwent a minimally invasive interbody lumbar fusion. Electronic medical records were analyzed for patient demographics, procedures, and perioperative and postoperative complications.

RESULTS: Between 2000 and 2009, 66 patients with an average age of 74.9 years (range, 70-86 years) underwent 68 lumbar interbody fusions procedures. The mean follow-up was 14.7 months (range, 1.5-50 months). The minimally invasive approaches included 41 cases of extreme lateral interbody fusion and 27 minimally invasive transforaminal lumbar interbody fusions. We observed 5 major (7.4%) and 17 minor (25%) complications. The 5 major complications consisted of 4 cases of interbody graft subsidence and 1 adjacent level disease. There were no intraoperative medical complications. There were no myocardial infarctions, pulmonary embolisms, hardware complications requiring removal, wound infections, major visceral, vascular, neural injuries, or death in the study period.

CONCLUSION: Minimally invasive interbody fusions can be performed in the elderly (ages 70 years and older) with an overall low rate of major complications. Graft subsidence in this population when not supplemented with posterior instrumentation is a concern. Age should not be a deterrent to performing complex minimally invasive interbody fusions in the elderly.

Neurosurgery 68:731–737, 2011 DOI: 10.1227/NEU.0b013e3182077373

Intraprocedural rupture is a dangerous complication of endovascular treatment. Small ruptured anterior communicating artery (ACoA) aneurysms and microaneurysms present a challenge for both surgical and endovascular therapies to achieve obliteration. An understanding of the complication rates of treating ruptured ACoA microaneurysms may help guide therapeutic options.

OBJECTIVE: To report the largest cohort of ACoA microaneurysms treated with endovascular therapy over the course of the past 10 years.

METHODS: We performed a retrospective review of 347 ACoA aneurysms treated in 347 patients at Cleveland Clinic and Emory University over a 10-year period. Patient demographics, aneurysmal rupture, size, use of balloon remodeling, patient outcomes, intraprocedural rupture, and rerupture were reviewed.

RESULTS: Rupture rates were examined by size for all patients and subgroups and dichotomized to evaluate for size ranges associated with increased rupture rates. The highest risk of rupture was noted in aneurysms less than 4 mm. Of 347 aneurysms, 74 (21%) were less than 4 mm. The intraprocedural rupture rate was 5% (18/347) for ACoA aneurysms of any size. There was an intraprocedural rupture rate of 2.9% (8/273) among ACoA aneurysms greater than 4 mm compared with 13.5% (10/74) in less than 4-mm aneurysms. Procedural rupture was a statistically significant predictor of modified Rankin score after adjusting for Hunt and Hess grades (HH).

CONCLUSION: ACoA aneurysms less than 4 mm have a 5-fold higher incidence of intraprocedural rerupture during coil embolization. Outcome is negatively affected by intraprocedural rerupture after adjusting for HH grade.