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The surgical management of chronic subdural hematoma

Neurosurg Rev DOI 10.1007/s10143-011-0349-y

Chronic subdural hematoma (cSDH) is an increasingly common neurological disease process. Despite the wide prevalence of cSDH, there remains a lack of consensus regarding numerous aspects of its clinical management. We provide an overview of the epidemiology and pathophysiology of cSDH and discuss several controversial management issues, including the timing of postoperative resumption of anticoagulant medications, the effectiveness of anti-epileptic prophylaxis, protocols for mobilization following evacuation of cSDH, as well as the comparative effectiveness of the various techniques of surgical evacuation.

A PubMed search was carried out through October 19, 2010 using the following keywords: “subdural hematoma”, “craniotomy”, “burr-hole”, “management”, “anticoagulation”, “seizure prophylaxis”, “antiplatelet”, “mobilization”, and “surgical evacuation”, alone and in combination. Relevant articles were identified and back-referenced to yield additional papers. A meta-analysis was then performed comparing the efficacy and complications associated with the various methods of cSDH evacuation.

There is general agreement that significant coagulopathy should be reversed expeditiously in patients presenting with cSDH. Although protocols for gradual resumption of anti-coagulation for prophylaxis of venous thrombosis may be derived from guidelines for other neurosurgical procedures, further prospective study is necessary to determine the optimal time to restart fulldose anti-coagulation in the setting of recently drained cSDH. There is also conflicting evidence to support seizure prophylaxis in patients with cSDH, although the existing literature supports prophylaxis in patients who are at a higher risk for seizures.

The published data regarding surgical technique for cSDH supports primary twist drill craniostomy (TDC) drainage at the bedside for patients who are high-risk surgical candidates with non-septated cSDH and craniotomy as a first-line evacuation technique for cSDH with significant membranes. Larger prospective studies addressing these aspects of cSDH management are necessary to establish definitive recommendations.

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Posterior fossa volume increase after surgery for Chiari malformation Type I: a quantitative assessment using magnetic resonance imaging and correlations with the treatment response

J Neurosurg 115:647–658, 2011.DOI: 10.3171/2010.11.JNS102148

The aim of this paper was to measure the posterior fossa (PF) volume increase resulting from a givensized occipital craniectomy in Chiari malformation Type I surgery and to analyze its correlations with the PF size and the treatment response, with the perspective of tailoring the amount of bone removal to the patient-specific PF dimensions.

Methods. Between January 2005 and June 2006, 11 adult patients with symptomatic Chiari malformation Type I underwent a standardized PF decompression. A prospective evaluation with clinical examination, functional grading, and MR imaging measurement protocols was performed pre- and postoperatively. A method is reported for the measurement of PF volume (PFV) after surgery. The degree of PFV increase was compared with the preoperative size of the PF and with the clinical outcome.

Results. All 11 patients improved postoperatively, with complete and partial recovery in 4 and 7 patients, respectively. No postoperative complication occurred after a mean follow-up period of 45 months. The mean relative increase in PFV accounted for 10% (range 1.5%–19.7%) of the initial PFV; the increase was greater in cases in which the PF was small (r = -0.52, p = 0.09) and the basiocciput was short (r = -0.37, p = 0.2). A statistically significant positive correlation was found between the degree of PFV increase and the treatment response (p = 0.014); complete recovery was observed with a PFV increase of 15% and partial recovery with an increase of 7%.

Conclusions. The treatment response is significantly influenced by the degree of PFV increase, which is dependent on the size of the PF and the extent of the craniectomy, suggesting that the optimal patient-specific PFV increase could be predicted on the basis of preoperative MR imaging and enhancing the perspective that the craniectomy size could be tailored to the individual PFV.

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Minimally invasive evacuation of spontaneous intracerebral hemorrhage using sonothrombolysis

J Neurosurg 115:592–601, 2011. DOI: 10.3171/2011.5.JNS10505

Catheter-based evacuation is a novel surgical approach for the treatment of brain hemorrhage. The object of this study was to evaluate the safety and efficacy of ultrasound in combination with recombinant tissue plasminogen activator (rt-PA) delivered through a microcatheter directly into spontaneous intraventricular (IVH) or intracerebral (ICH) hemorrhage in humans.

Methods. Thirty-three patients presenting to the Swedish Medical Center in Seattle, Washington, with ICH and IVH were screened between November 21, 2008, and July 13, 2009, for entry into this study. Entry criteria included the spontaneous onset of intracranial hemorrhage ≥ 25 ml and/or IVH producing ventricular obstruction. Nine patients (6 males and 3 females, with an average age of 63 years [range 38–83 years]) who met the entry criteria consented to participate and were entered into the trial. A ventricular drainage catheter and an ultrasound microcatheter were stereotactically delivered together, directly into the IVH or ICH. Recombinant tissue plasminogen activator and 24 hours of continuous ultrasound were delivered to the clot. Gravity drainage was performed. In patients with IVHs, 3 mg of rt-PA was injected; in patients with intraparenchymal hemorrhages, 0.9 mg of rt-PA was injected. The rt-PA was delivered in 3 doses over 24 hours.

Results. All patients had significant volume reductions in the treated hemorrhage. The mean percentage volume reduction after 24 hours of therapy, as determined on CT and compared with pretreatment stability scans, was 59 ± 5% (mean ± SEM) for ICH and 45.1 ± 13% for IVH (1 patient with ICH was excluded from analysis because of catheter breakage). There were no intracranial infections and no significant episodes of rebleeding according to clinical or CT assessment. One death occurred by 30 days after admission. Clinical improvements as determined by a decrease in the National Institutes of Health Stroke Scale score were demonstrated at 30 days after treatment in 7 of 9 patients. The rate of hemorrhage lysis was compared between 8 patients who completed treatment, and patient cohorts treated for IVH and ICH using identical doses of rt-PA and catheter drainage but without the ultrasound (courtesy of the MISTIE [Minimally Invasive Surgery plus T-PA for Intracerebral Hemorrhage Evacuation] and CLEAR II [Clot Lysis Evaluating Accelerated Resolution of Intraventricular Hemorrhage II] studies). Compared with the MISTIE and CLEAR data, the authors observed a faster rate of lysis during treatment for IVH and ICH in the patients treated with sonolysis plus rt-PA versus rt-PA alone.

Conclusions. Lysis and drainage of spontaneous ICH and IVH with a reduction in mass effect can be accomplished rapidly and safely through sonothrombolysis using stereotactically delivered drainage and ultrasound catheters via a bur hole. A larger clinical trial with catheters specifically designed for brain blood clot removal is warranted.

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Effect of Antibiotic-Impregnated Shunts on Infection Rate in Adult Hydrocephalus: A Single Institution’s Experience

Neurosurgery 69:625–629, 2011 DOI: 10.1227/NEU.0b013e31821bc435

Cerebrospinal fluid (CSF) shunt infection remains a major cause of morbidity and mortality in the treatment of hydrocephalus. Studies have demonstrated the efficacy of antibiotic-impregnated shunt (AIS) systems in reducing CSF shunt infections in pediatric patients. Fewer studies evaluate the efficacy of AIS systems in adult hydrocephalus.

OBJECTIVE: To determine whether categorical conversion to AIS shunt systems reduced the incidence of shunt infection in adults.

METHODS: All adult patients undergoing CSF shunt insertion over a 7-year period were retrospectively reviewed (2004-2009). In 2006, a categorical switch to AIS catheters was made. Before 2006, standard nonimpregnated shunt catheters were used. We retrospectively reviewed the first 250 cases of AIS catheter implantation and compared them with the immediately preceding 250 non-AIS cases to assess 1-year incidence of CSF shunt infection.

RESULTS: Five hundred shunt surgeries were performed for normal-pressure hydrocephalus in 378 patients (76%), pseudotumor cerebri in 83 patients (17%), and various obstructive/communicating hydrocephalus etiologies in 40 patients (8%). All patients were followed for 12 months. The mean age was 60 6 18 years. Baseline characteristics were similar between AIS (n = 250) and non-AIS (n = 250) cohorts. Overall, 13 patients (2.6%) experienced CSF shunt infection, occurring a mean of 2 6 2 months postoperatively. Shunt infection incidence was decreased in AIS (1.2%) vs non-AIS (4.0%) cohorts (P = .0492). Staphylococcus epidermidis was the most common pathogen in AIS and non-AIS cohorts. Oxacillin resistance was not increased in the AIS cohort.

CONCLUSION: Categorical conversion to AIS catheters was associated with a reduced incidence of shunt infection. AIS catheters may be a reliable instrument for decreasing perioperative shunt colonization and subsequent infection in adults with hydrocephalus.

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Bare Platinum vs Matrix Detachable Coils for the Endovascular Treatment of Intracranial Aneurysms: A Multivariate Logistic Regression Analysis and Review of the Literature

Neurosurgery 69:557–565, 2011 DOI: 10.1227/NEU.0b013e31821a86da

Despite increasing acceptance of endovascular coiling for treating intracranial aneurysms, incomplete occlusion remains a limitation. Attempts to reduce recanalization have prompted creation of polyglycolic/polylactic acid–coated (Matrix) coils shown to improve neointima formation; however, previous publications demonstrate conflicting results regarding their efficacy. Few studies account for factors influencing recurrence, and only 4 studies include bare platinum (BP) coil control groups.

OBJECTIVE: To compare initial and short- and mid-term occlusion as well as retreatment rates using Matrix compared with BP coils.

METHODS: Retrospective review of patients undergoing coiling of cerebral aneurysms from 2001 to 2005 was performed. Analysis included a multivariate logistic regression model designed to detect a 35% absolute difference in initial occlusion between coil treatment groups with 80% power.

RESULTS: Complete initial occlusion was achieved in 64% of BP (n = 45) and 63% of Matrix (n = 56) cases (P = 1.0). Follow-up occlusion rates in the short term and mid term were 52% and 60%, respectively, for BP cases and 42% and 67%, respectively, for Matrix cases (P = .24 and P = .38, respectively). After adjusting for size, morphology, volumetric packing density, location, rupture, and balloon remodeling, no difference in initial and subsequent occlusion or retreatment rates for BP coils versus Matrix coils was appreciated.

CONCLUSION: After controlling for factors influencing recanalization, this investigation failed to show a significant difference between coil groups.

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Surgical clipping as the preferred treatment for aneurysms of the middle cerebral artery

Acta Neurochir. DOI 10.1007/s00701-011-1139-6

In recent years the endovascular treatment of intracranial aneurysms (coiling) has progressively gained recognition, particularly after the publication of the International Subarachnoid Aneurysm Trial (ISAT) in 2002. Despite the fact that in ISAT middle cerebral artery (MCA) aneurysms were clearly underrepresented, the study is often used as an argument to favor coiling above surgery in MCA aneurysms. Taken into account that MCA aneurysms are very well accessible for surgery, a contemporary assessment of the benefits of a preferred surgical strategy for MCA aneurysms was performed in a tertiary neurovascular referral center.

Methods A prospectively kept single-center database of 151 consecutive patients with an MCA aneurysm was reviewed over a 6-year period (2001–2006). Long-term follow-up after surgical treatment of a ruptured MCA aneurysm was obtained in 74 out of 77 (96%) patients. The outcome was compared with relevant series in the literature.

Results After a mean follow-up of 4.7 years, 59 out of 74 surgically treated patients (80%) with a ruptured MCA aneurysm had a good outcome (mRankin 0–2). All patients with an unruptured MCA aneurysm also had a good outcome after clipping. This is well-matched with the findings of the literature search, and competitive with the endovascular results.

Conclusion Surgical clipping is recommended as the principal treatment strategy for MCA aneurysms. This is not only ethically defendable in view of the surgical results but also in line with a strategy to maintain surgical experience within centralized neurovascular centers.

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Preoperative Functional Mapping for Rolandic Brain Tumor Surgery: Comparison of Navigated Transcranial Magnetic Stimulation to Direct Cortical Stimulation

Neurosurgery 69:581–589, 2011 DOI: 10.1227/NEU.0b013e3182181b89

Transcranial magnetic stimulation (TMS) is the only noninvasive method for presurgical stimulation mapping of cortical function. Recent technical advancements have significantly increased the focality and usability of the method.

OBJECTIVE: To compare the accuracy of a 3-dimensional magnetic resonance imaging– navigated TMS system (nTMS) with the gold standard of direct cortical stimulation (DCS).

METHODS: The primary motor areas of 20 patients with rolandic tumors were mapped preoperatively with nTMS at 110% of the individual resting motor threshold. Intraoperative DCS was available from 17 patients. The stimulus locations eliciting the largest electromyographic response in the target muscles (‘‘hotspots’’) were determined for both methods.

RESULTS: The nTMS and DCS hotspots were located on the same gyrus in all cases. The mean 6 SEM distance between the nTMS and DCS hotspots was 7.83 6 1.18 mm for the abductor pollicis brevis (APB) muscle (n = 15) and 7.07 6 0.88 mm for the tibialis anterior muscle (n = 8). When a low number of DCS stimulations was performed, the distance between the nTMS and DCS hotspots increased substantially (r = 20.86 for APB). After the exclusion of the cases with , 15 DCS APB responses, the mean 6 SEM distance between the hotspots was only 4.70 6 1.09 mm for APB (n = 8).

CONCLUSION: Peritumoral mapping of the motor cortex by nTMS agreed well with the gold standard of DCS. Thus, nTMS is a reliable tool for preoperative mapping of motor function.

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Volumetric analysis of syringomyelia following hindbrain decompression for Chiari malformation Type I: syringomyelia resolution follows exponential kinetics

Neurosurg Focus 31 (3):E4, 2011. DOI: 10.3171/2011.6.FOCUS11106

Resolution of syringomyelia is common following hindbrain decompression for Chiari malformation, yet little is known about the kinetics governing this process. The authors sought to establish the volumetric rate of syringomyelia resolution.

Methods. A retrospective cohort of patients undergoing hindbrain decompression for a Chiari malformation Type I with preoperative cervical or thoracic syringomyelia was identified. Patients were included in the study if they had at least 3 neuroimaging studies that detailed the entirety of their preoperative syringomyelia over a minimum of 6 months postoperatively. The authors reconstructed the MR images in 3 dimensions and calculated the volume of the syringomyelia. They plotted the syringomyelia volume over time and constructed regression models using the method of least squares. The Akaike information criterion and Bayesian information criterion were used to calculate the relative goodness of fit. The coefficients of determination R2 (unadjusted and adjusted) were calculated to describe the proportion of variability in each individual data set accounted for by the statistical model.

Results. Two patients were identified as meeting inclusion criteria. Plots of the least-squares best fit were identified as 4.01459e-0.0180804x and 13.2556e-0.00615859x. Decay of the syringomyelia followed an exponential model in both patients (R2 = 0.989582 and 0.948864).

Conclusions. Three-dimensional analysis of syringomyelia resolution over time enables the kinetics to be estimated. This technique is yet to be validated in a large cohort. Because syringomyelia is the final common pathway for a number of different pathological processes, it is possible that this exponential only applies to syringomyelia related to treatment of Chiari malformation Type I.

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Convexity meningiomas: study of recurrence factors with special emphasis on the cleavage plane in a series of 100 consecutive patients

J Neurosurg 115:491–498, 2011. DOI: 10.3171/2011.4.JNS101922

Convexity meningiomas are expected to have a low recurrence rate given their classically “easy resectability.” Nonetheless, recurrence can occur. Factors playing a role in their recurrence are analyzed here, including the extent of resection and tumor histological type, among others, with a special emphasis on the cleavage plane.

Methods. The authors reviewed 100 cases of convexity meningiomas surgically treated between 1987 and 2001 with a median follow-up of 86 months (range 2–16 years). Preoperative and postoperative functional status, Simpson resection grade, histological type, and intraoperative surgical plane with pial vessel invasion were studied and cor- related with the recurrence rate.

Results. The average tumor size was 3.6 ± 0.4 cm. The pre- and postoperative Karnofsky Performance Scale scores were 92.6 ± 4.6 and 97.9 ± 2.2, respectively. Ninety-five lesions were benign (WHO Grade I) and 5 were atypical (WHO Grade II). Ninety-one and 9 tumors were subjected to Simpson Grade 1 and 3 resections (three Grade 3a and six Grade 3b), respectively. Surgical deaths did not occur. After a mean follow-up of 7.2 years, 4 meningiomas recurred; 2 (2.2%) after Simpson Grade 1 resections and 2 after Simpson Grade 3 (3a and 3b) resections (22.2%; p = 0.0034). When just the subgroup of Simpson Grade 1/WHO Grade I was studied, the recurrence rate decreased to 1.2% (1 of 86 cases). The recurrence of WHO Grade I tumors was higher in the subpial group than in the extrapial group (p = 0.025). No difference in recurrence according to the cleavage plane was seen in the WHO Grade II sub- group (p = 0.361). As for the subpial group, no difference in recurrence was noted between the WHO Grade I and II subgroups (p = 0.608). Importantly, however, the extrapial subgroup of WHO Grade II lesions had a higher recurrence rate compared with its counterpart in the WHO Grade I subgroup (p = 0.005).

Conclusions. Pial and vascular invasion affect the recurrence rate in convexity meningioma surgery. The recurrence rate of WHO Grade I tumors was higher among those with a subpial plane of dissection than among those with an extrapial one. Histological type did not determine the degree of pial invasion in WHO Grade I and II lesions.

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Supraorbital keyhole approach for removal of midline anterior cranial fossa meningiomas

Neurosurg Rev. DOI 10.1007/s10143-011-0340-7

The paper describes a retrospective study of a consecutive series of 20 midline anterior cranial fossa meningiomas (five of the olfactory groove, 14 of the tuberculum sellae, and one clinoidal), which were operated on via a supraorbital keyhole approach between 2002 and 2008.

The series includes three males and 17 females (mean age 57 years, mean size of the tumors 3.5×3 cm, and mean follow-up 48 months). Gross total excision was achieved in 18 cases and subtotal resection in two. Out of 14 patients with visual deficits, nine patients improved, one remained stable, and three deteriorated. Two patients presented a recurrence 3 years after surgery. One peri-operative death was recorded.

The subgroup of patients with tuberculum sellae meningiomas was analyzed in details. A meta-analysis of the major series of such meningiomas in the last 20 years has been performed in order to compare results of different surgical techniques. With regard to primary outcomes of these tumors, gross total removal, restoration of visual function, morbidity, mortality, and recurrence rates, the supraorbital approach, for selected cases, seems to offer valuable results, comparable with those reported in conventional and endoscopic approaches and with very low surgical aggressiveness. However, statistical data available from the literature, particularly on visual function, are still too limited to draw definitive conclusions.

The best surgical option for the individual patient cannot yet be standardized and should be chosen on the basis of tumor anatomy, pre-operative clinical symptoms, and surgeon’s experience.

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Neurocytomas: Long-term experience of a single institution

Neuro-Oncology 13(9):943–949, 2011. doi:10.1093/neuonc/nor074

There is a lack of studies reporting on outcomes of control and treatment toxicities for neurocytomas.

A 25-year retrospective review of a tertiary center’s experience with neurocytomas was completed to report on these outcomes. All cerebral neurocytoma cases (19 patients; median age, 31 years; range, 18–62 years; 18 intraventricular and 1 extraventricular) treated between 1984 and 2009 were analyzed, including central pathology and radiology reviews.

Median follow-up was 104.5 months (range, 0.75–261.7 months). Primary treatment was surgery alone (n = 18 patients), followed by surgery and adjuvant radiotherapy (n = 1). The crude local control rate after surgery was 68% for all cases (cerebral neurocytomas) and 74% for central neurocytomas. Salvage therapies included further surgery (n = 4), radiation (n = 3), and chemotherapy (n = 1). Ten-year Kaplan-Meier overall and relapse-free survival rates were 82% and 62% and 81% and 57%, respectively, for all cases and for central neurocytomas only. The median overall survival and relapse-free survival were 104.5 and 79.3 months, respectively, for all cases and for central neurocytomas. Ten patients had grade 3/4 toxicity, and 1 patient had a grade 5 perioperative hemorrhage that resulted in death 23 days after surgery. Late grade 3/4 toxicities occurred in 9 patients. Three patients had permanent grade 2 motor or cognitive deficits.

We provide the first report outlining toxicities and survival outcomes in a series of 19 patients. Our experience suggests that initial surgery provides durable local control rates in two-thirds of patients, with low risk for significant permanent deficits. Salvage therapy with surgery and/or radiation provides durable local control in tumors that recur after surgery.

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Motor-evoked potentials (MEP) during brainstem surgery to preserve corticospinal function

Acta Neurochir (2011) 153:1753–1759. DOI 10.1007/s00701-011-1065-7

Brainstem surgery bears a risk of damage to the corticospinal tract (CST). Motor-evoked potentials (MEPs) are used intraoperatively to monitor CST function in order to detect CST damage at a reversible stage and thus impede permanent neurological deficits. While the method of MEP is generally accepted, warning criteria in the context of brainstem surgery still have to be agreed on.

Method We analyzed 104 consecutive patients who underwent microsurgical resection of lesions affecting the brainstem. Motor grade was documented prior to surgery, early postoperatively and at discharge. A baseline MEP stimulation intensity threshold was defined and intraoperative testing aimed to keep MEP response amplitude constant. MEPs were considered deteriorated and the surgical team was notified whenever the threshold was elevated by ≥20 mA or MEP response fell under 50%.

Findings On the first postoperative day, 18 patients experienced new paresis that resolved by discharge in 11. MEPs deteriorated in 39 patients, and 16 of these showed new postoperative paresis, indicating a 41% risk of new paresis. In the remaining 2/18 patients, intraoperative MEPs were stable, although new paresis appeared postoperatively. In one of these patients, intraoperative hemorrhage caused postoperative swelling, and the new motor deficit persisted until discharge. Of all 104 patients, 7 deteriorated in motor grade at discharge, 92 remained unchanged, and 5 patients have improved.

Conclusions Adjustment of surgical strategy contributed to good motor outcome in 33/39 patients. MEP monitoring may help significantly to prevent motor deficits during demanding neurosurgical procedures on the brainstem.

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Impact of Multiorgan Fusion Imaging and Interactive 3-Dimensional Visualization for Intraventricular Neuroendoscopic Surgery

Neurosurgery 69[ONS Suppl 1]:ons40–ons48, 2011. DOI: 10.1227/NEU.0b013e318211019a

Imaging technologies have evolved to meet the demand for improved presurgical simulations, particularly with the introduction of endoscopic surgery in the neurosurgical field.

OBJECTIVE: To evaluate the effectiveness of a 3-dimensional interactive visualization method with a computer graphics model, which was created using hybrid rendering and multimodal fusion methods for neuroendoscopic surgery, and to assess whether the 2-dimensional interactive visualization method could effectively represent the microsurgical anatomical information necessary for endoscopic surgery compared with conventional 3-dimensional computer graphics models.

METHODS: Ten patients scheduled for neuroendoscopic surgery for intraventricular lesions were included in the study. For the 3-dimensional interactive visualization method, a hybrid model of volume and surface rendering was created from magnetic resonance images combined with computed tomography and positron emission tomography. Preoperative radiographic images were fused with the normalized mutual information method. Visibility of anatomic structures was compared between the multifusion models and nonfusion models created from only heavy-T2-weighted images that rely solely on the surface rendering method.

RESULTS: The average visibility score of the multifusion models was 97.5% (range, 95.6% to 100%), which was significantly higher than that for nonfusion models (35.9% to 64.1%; P = .002). The multifusion model represents an improved visualization method for preoperative virtual simulation for neuroendoscopic intraventricular surgery.

CONCLUSION: Our 3-dimensional imaging method is superior to conventional methods and will greatly improve the safety and effectiveness of neuroendoscopic surgical procedures for complex intraventricular lesions.

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Cranial vault remodeling for sagittal craniosynostosis in older children

Neurosurg Focus 31 (2):E3, 2011,DOI: 10.3171/2011.5.FOCUS1196

Sagittal craniosynostosis is the most common form of craniosynostosis and is commonly treated within the first year of life. Optimal treatment of patients older than 1 year of age is not well characterized. The authors reviewed cases of sagittal craniosynostosis involving patients who were treated surgically at their institution when they were older than 1 year in order to determine the rate of intracranial hypertension (ICH), potential to develop nonhealing cranial defects, and the need for various surgical procedures to treat the more mature phenotype.

Methods. A retrospective chart review was conducted of all cases in the Children’s Hospital of Pittsburgh Neurosurgery Database involving patients who underwent cranial vault remodeling for scaphocephaly after 1 year of age between October 2000 and December 2010.

Results. Ten patients were identified who met the inclusion criteria. Five patients underwent anterior two-thirds cranial vault remodeling procedures, 3 patients underwent posterior vault remodeling, and 2 patients underwent 2-staged total vault remodeling. All patients had improved head shapes, and mean cephalic indices improved from 65.4 to 69.1 (p = 0.05). Six patients exhibited signs of ICH. No patients with more than 3 months of follow-up exhibited palpable calvarial defects.

Conclusions. Patients with sagittal synostosis treated after 1 year of age demonstrate increased rates of ICH, warranting diligent evaluations and surveillance to detect it; rarely develop clinically significant cranial defects if appropriate bone grafting is performed at the time of surgery; and achieve acceptable improvements in head shape.

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Long-term Outcomes After Gamma Knife Radiosurgery for Patients With a Nonfunctioning Pituitary Adenoma

Neurosurgery 69:284–293, 2011 DOI: 10.1227/NEU.0b013e31821bc44e

Nonfunctioning pituitary adenomas recur after microsurgery. Gamma Knife radiosurgery (GKRS) has been used to treat recurrent adenomas.

OBJECTIVE: To evaluate the long-term rates of tumor control and development of hypopituitarism in patients with nonfunctioning pituitary adenomas after GKRS.

METHODS: Forty-eight patients with a nonfunctioning pituitary adenoma treated between 1991 and 2004 at the University of Virginia were studied. All patients had more than 4 years of clinical and imaging follow-up.

RESULTS: All patients underwent follow-up imaging and endocrine evaluations, with a duration ranging from 50 to 215 months (median, 80.5 months) and 57 to 201 months (median, 95 months), respectively. New hormone deficiency after GKRS occurred in 19 of 48 patients (39%). Corticotropin/cortisol deficiency developed in 8% of patients, thyroid hormone deficiency in 20.8%, gonadotropin deficiency in 4.2%, growth hormone/insulin-like growth factor 1 in 16.7%, and diabetes insipidus in 2%. Panhypopituitarism including diabetes insipidus developed in 1 patient. Overall, control of tumor volume was 83%. Tumor volume decreased in 36 patients (75%), increased in 8 patients (17%), and was unchanged in 4 patients (8%). Tumor volumes greater than 5 mL at the time of GKRS were associated with a significantly greater rate of growth (P = .003) compared with an adenoma with a volume of 5 mL or less.

CONCLUSION: GKRS resulted in a high and durable rate of tumor control in patients with a nonfunctioning pituitary adenoma. A higher preoperative tumor volume was associated with an increased rate of tumor growth.

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Natural history of Chiari malformation Type I

J Neurosurg Pediatrics 8:214–221, 2011.  DOI: 10.3171/2011.5.PEDS1122

The natural history of the Chiari malformation Type I (CM-I) is incompletely understood. The authors report on the outcome of a large group of patients with CM-I that were initially selected for nonsurgical management.

Methods. The authors identified 147 patients in whom CM-I was diagnosed on MR imaging, who were not offered surgery at the time of diagnosis, and in whom at least 1 year of clinical and MR imaging follow-up was available after the initial CM-I diagnosis. These patients were included in an outcome analysis.

Results. Patients were followed clinically and by MR imaging for a mean duration of 4.6 and 3.8 years, respectively. Of the 147 patients, 9 had new symptoms attributed to the CM-I during the follow-up interval. During this time, development of a spinal cord syrinx occurred in 8 patients; 5 of these patients had a prior diagnosis of a presyrinx state or a dilated central canal. Spontaneous resolution of a syrinx occurred in 3 patients. Multiple CSF flow studies were obtained in 74 patients. Of these patients, 23 had improvement in CSF flow, 39 had no change, and 12 showed worsening CSF flow at the foramen magnum. There was no significant change in the mean amount of cerebellar tonsillar herniation over the follow-up period. Fourteen patients underwent surgical treatment for CM-I. There were no differences in initial cerebellar tonsillar herniation or CSF flow at the foramen magnum in those who ultimately underwent surgery compared with those who did not.

Conclusions. In patients with CM-Is that are selected for nonsurgical management, the natural history is usually benign, although spontaneous improvement and worsening are occasionally seen.

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Increased incidence of nonaccidental head trauma in infants associated with the economic recession

J Neurosurg Pediatrics 8:171-176, 2011.DOI: 10.3171/2011.5.PEDS1139

Nonaccidental head trauma (NAHT) is a major cause of death in infants. During the current economic recession, the authors noticed an anecdotal increase in infants with NAHT without an increase in the overall number of infants admitted with traumatic injuries. An analysis was performed to determine whether there was an association between economic recession and NAHT.

Methods. With Institutional Review Board approval, the trauma database was searched for NAHT in infants 0–2 years old during nonrecession (December 2001 to November 2007) and recession (December 2007 to June 2010) periods. Incidence is reported as infants with NAHT per month summarized over time periods. Continuous variables were compared using Mann-Whitney U-tests, and proportions were compared using the Fisher exact test.

Results. Six hundred thirty-nine infant traumas were observed during the study time period. From the nonrecession to the recession period, there was an 8.2% reduction in all traumas (458 in 72 months [6.4 /month] vs 181 in 31 months [5.8/month]) and a 3.5% reduction in accidental head traumas (142 in 72 months [2.0/month] vs 59 in 31 months [1.9/month]). Nonaccidental head trauma accounted for 14.6% of all traumas (93/639). The median patient age was 4.0 months and 52% were boys. There were no significant differences in the representative counties of referral or demographics between nonrecession and recession populations (all p > 0.05). The monthly incidence rates of NAHT doubled from nonrecession to recession periods (50 in 72 months [0.7/month] vs 43 in 31 months [1.4/month]; p = 0.01). During this recession, at least 1 NAHT was reported in 68% of the months compared with 44% of the months during the nonrecession period (p = 0.03). The severity of NAHTs also increased, with a greater proportion of deaths (11.6% vs 4%, respectively; p = 0.16) and severe brain injury (Glasgow Coma Scale score ≤ 8: 19.5% vs 4%, respectively; p = 0.06) during the recession.

Conclusions. In the context of an overall reduction in head trauma, the significant increase in the incidence of NAHT appears coincident with economic recession. Although the cause is likely multifactorial, a full analysis of the basis of this increase is beyond the scope of this study. This study highlights the need to protect vulnerable infants during challenging economic times.

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Outcome of surgically treated giant internal carotid artery aneurysms

Acta Neurochir (2011) 153:1611–1619. DOI 10.1007/s00701-011-1021-6

Internal carotid artery (ICA) is predominant localization of giant intracranial aneurysms (GIAs). The rupture of GIA is supposed to be related to higher risk of poor clinical outcome. Although endovascular techniques are still being developed, they seem to be unsatisfactory in the mean of GIAs.

Methods Included in the retrospective analysis were 78 giant and 250 smaller surgically treated ICA aneurysms. Exclusion criteria were multiple and blood blister-like aneurysms. Neurological deficit on admission, clinical and radiological presentation, gender, age, segment of ICA, surgical methods, accessory techniques and complications were analyzed. Death rate and short- and long-term outcome of giant aneurysms were compared with smaller aneurysms and risk factors formortality, unfavorable short- and long-term outcome were determined.

Results There was no difference in general and surgical complications between ICA aneurysm size groups, as well as in occurrence of newly diagnosed neurological deficit after the operation. There were similar mortality rates, proportion of unfavorable outcome, and low health related quality of life for giant and smaller aneurysms. A 12.2% death rate for all ICA aneurysms was achieved. Trapping method as well as Fisher grades 3 and 4 increased mortality risk in the smaller aneurysm group. No significant factors were related to an unfavorable outcome in the ruptured giant aneurysm group. Patients older than 65, Hunt-Hess grades 4 and 5, Fisher grade 4, and newly diagnosed deficit after operation were connected with unfavorable outcome in the ruptured smaller aneurysm group. Newly diagnosed neurological deficit was also an unfavorable outcome risk factor in both giant and smaller ICA unruptured aneurysms. No difference was noted in long-term health-related quality of life between the giant and smaller ICA groups. Higher age and presence of concomitant disease were independent factors affecting quality of life, although obtained data were incomplete.

Conclusions The study breaks the stereotype of unfavorable giant ICA aneurysms treatment results. Mortality rate, shortand long-term outcome after the operation of giant and smaller ICA aneurysms are similar. Higher age, patients’ condition at admission, and the amount of extravasated blood and trapping method are poor prognostic factors in patients with smaller ICA aneurysm

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Nonfusion stabilization of the degenerative lumbar spine

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

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

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

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

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

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Dural Landmark to Locate the Internal Auditory Canal in Large and Giant Vestibular Schwannomas: The Tübingen Line

Neurosurgery 69[ONS Suppl 1]:ons99–ons102, 2011.  DOI: 10.1227/NEU.0b013e31821664c6

In cases of large and giant vestibular schwannomas (VS), the visualization of the internal auditory canal (IAC) opening is difficult or impossible.

OBJECTIVE: To describe the Tübingen line and explore its relationships with the IAC as a landmark to help locate the IAC.

METHODS: Ten cadaveric heads were used in this study. Between 2004 and 2009, the senior author (M.T.) used the Tübingen line as a landmark to recognize the IAC in 300 consecutive patients with VS. To locate the Tübingen  line, the initial step was to identify several vertical foldings of dura located around the area of the vestibular aqueduct. After this, foldings upward consistently reached a linear level where all of the foldings ended and the dura tightly adhered to the bony surface in a smooth, foldless shape.

RESULTS: The Tübingen line was identified in all temporal bones studied and in all 300 patients operated on, with the exception of 2 cases (,1%). Removal of the bone just above the Tübingen line located the IAC in all temporal bone specimens studied. Similarly, the surgical cases showed that the Tübingen line helped locate the IAC in all patients.

CONCLUSION: The Tübingen line is an easy, consistent, and safe method to locate the projection of the IAC along the posterior surface of the temporal bone.

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