Month: December 2012

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Lateral Extracavitary vs Costotransversectomy Approaches to the Thoracic Spine

Lateral Extracavitary vs Costotransversectomy Approaches to the Thoracic Spine- Reflections on Lessons Learned Lateral Extracavitary vs Costotransversectomy Approaches to the Thoracic Spine- Reflections on Lessons Learned_2

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.

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Frontal cortico-subcortical functional anatomy

Subcortical surgical anatomy of the lateral frontal region

J Neurosurg 117:1053–1069, 2012

Recent neuroimaging and surgical results support the crucial role of white matter in mediating motor and higher-level processing within the frontal lobe, while suggesting the limited compensatory capacity after damage to subcortical structures. Consequently, an accurate knowledge of the anatomofunctional organization of the pathways running within this region is mandatory for planning safe and effective surgical approaches to different diseases. The aim of this dissection study was to improve the neurosurgeon’s awareness of the subcortical anatomofunctional architecture for a lateral approach to the frontal region, to optimize both resection and postoperative outcome.

Methods. Ten human hemispheres (5 left, 5 right) were dissected according to the Klingler technique. Proceeding lateromedially, the main association and projection tracts as well as the deeper basal structures were identified. The authors describe the anatomy and the relationships among the exposed structures in both a systematic and topographical surgical perspective. Structural results were also correlated to the functional responses obtained during resections of infiltrative frontal tumors guided by direct cortico-subcortical electrostimulation with patients in the awake condition.

Results. The eloquent boundaries crucial for a safe frontal lobectomy or an extensive lesionectomy are as follows: 1) the motor cortex; 2) the pyramidal tract and premotor fibers in the posterior and posteromedial part of the surgical field; 3) the inferior frontooccipital fascicle and the superior longitudinal fascicle posterolaterally; and 4) underneath the inferior frontal gyrus, the head of the caudate nucleus, and the tip of the frontal horn of the lateral ventricle in the depth.

Conclusions. Optimization of results following brain surgery, especially within the frontal lobe, requires a perfect knowledge of functional anatomy, not only at the cortical level but also with regard to subcortical white matter connectivity.

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Awake mapping for resection of cavernous angioma and surrounding gliosis in the left dominant hemisphere

Awake mapping for resection of cavernous angioma and surrounding gliosis in the left dominant hemisphere

J Neurosurg 117:1076–1081, 2012

Maximal resection of symptomatic cavernous angioma (CA), including its surrounding gliosis if possible, has been recommended to minimize the risk of seizures or (re)bleeding. However, despite recent neurosurgical advances, such extensive CA removal is still a challenge in eloquent areas. The authors report a consecutive series of patients who underwent awake surgery for CA within the left dominant hemisphere in which intraoperative cortical– subcortical electrical stimulation was used.

Methods. Nine patients harboring a CA that was revealed by seizures in 6 cases and bleeding in 3 cases underwent resection. All CAs were located in the left dominant hemisphere: 3 temporal, 2 insular, 2 parietal, and 2 in the parietotemporal region. Awake mapping was performed in all cases by using intraoperative cortical–subcortical electrical stimulation and ultrasonography (except in 1 insular CA in which a neuronavigation system was used).

Results. Total removal of the CA was achieved in all patients, with identification and preservation of language and sensory-motor structures. In addition, the pericavernomatous gliosis was removed in 7 cases, according to the functional boundaries provided by intraoperative subcortical stimulation. In 2 cases, subcortical mapping revealed eloquent areas within the surrounding gliosis, which was voluntarily avoided. There was no postsurgical permanent deficit, no rebleeding, and no epilepsy in 7 cases (2 patients had rare seizures in the 1st year or two after surgery, and then complete arrest), with a mean follow-up of 28.5 months (range 3–64 months).

Conclusions. These results suggest that intraoperative cortical–subcortical stimulation in awake patients represents a valuable adjunct to image-guided surgery with the aim of selecting the safer surgical approach for CAs involving eloquent areas. Moreover, such online mapping can be helpful when removing the pericavernomatous gliosis while preserving functional structures, which can persist within the hemosiderin rim. Thus, the authors propose that awake surgery be routinely considered, both to optimize the resection and to improve the quality of life through seizure control and avoidance of (re)bleeding for CAs located in the left dominant hemisphere.

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The Anatomical and Electrophysiological Subthalamic Nucleus Visualized by 3-T Magnetic Resonance Imaging

The Anatomical and Electrophysiological Subthalamic Nucleus Visualized by 3-T Magnetic Resonance Imaging

Neurosurgery 71:1089–1095, 2012

Accurate localization of the subthalamic nucleus (STN) is critical to the success of deep brain stimulation surgery for Parkinson disease. Recent developments in high-field-strength magnetic resonance imaging (MRI) have made it possible to visualize the STN in greater detail. However, the relationship of the MR-visualized STN to the anatomic, electrophysiological, or atlas-predicted STN remains controversial.

OBJECTIVE: To evaluate the size of the STN visualized on 3-T MRI compared with anatomic measurements in cadaver studies and to compare the predictions of 3-T MRI and those of the Schaltenbrand-Wahren (SW) atlas for intraoperative STN microelectrode recordings.

METHODS: We evaluated the STN by 3-T MRI and intraoperative microelectrode recordings in 20 Parkinson disease patients undergoing deep brain stimulation surgery. We compared our findings with anatomic cadaver studies and with the individually scaled SW atlas-based predictions for each patient.

RESULTS: The dimensions of the 3-T MR-visualized STN were very similar to those of the largest anatomic study (MRI length, width, and height: 9.8 6 1.6, 11.5 6 1.6, and 3.7 6 0.7 mm, respectively; n = 40; cadaver length, width, and height: 9.3 6 0.7, 10.6 6 0.9, and 3.1 6 0.5 mm, respectively; n = 100). The amount of STN traversed during intraoperative microelectrode recordings was better correlated to the 3-T MR-visualized STN than the SW atlas-predicted STN (R = 0.38 vs R = 20.17).

CONCLUSION: The STN as visualized on 3-T MRI corresponds well with cadaveric anatomic studies and intraoperative electrophysiology. STN visualization with 3-T MRI may be an improvement over SW atlas-based localization for STN deep brain stimulation surgery in Parkinson disease.

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Increased Frameless Stereotactic Accuracy With High-Field Intraoperative Magnetic Resonance Imaging

Captura de pantalla 2012-12-23 a la(s) 11.07.11 

Neurosurgery 71[ONS Suppl 2]:ons321–ons328, 2012

Frameless stereotaxy commonly registers preoperative magnetic resonance imaging (MRI) to patients by using surface scalp anatomy or adhesive fiducial scalp markers. Patients’ scalps may shift slightly between preoperative imaging and final surgical positioning with pinion placement, introducing error. This might be reduced when frameless stereotaxy is performed in a high-field intraoperative MRI (iMRI), as patients are positioned before imaging. This could potentially improve accuracy.

OBJECTIVE: To compare frameless stereotactic accuracy using a high-field iMRI with that using standard preoperative MRI.

METHODS: Data were obtained in 32 adult patients undergoing frameless stereotacticguided brain tumor surgery. Stereotactic images were obtained with 1.5T MRI scanner either preoperatively (14 patients) or intraoperative (18 patients). System-generated accuracy measurements and distances from the actual center of each fiducial marker to that represented by neuronavigation were recorded. Finally, accuracy at multiple deep targets was assessed by using a life-sized human head stereotactic phantom in which fiducials were placed on deformable foam to mimic scalp.

RESULTS: System-generated accuracy measurements were significantly better for the iMRI group (mean 6 SEM = 1.04 6 0.05 mm) than for the standard group (1.82 6 0.09 mm; P , .001). Measured distances from the actual center of scalp fiducial markers to that represented by neuronavigation were also significantly smaller for iMRI (1.72 6 0.10 mm) in comparison with the standard group (3.17 6 0.22 mm; P , .001). Deep accuracy in the phantom model was significantly better with iMRI (1.67 6 0.12 mm) than standard imaging (2.28 6 0.14 mm; P = .003).

CONCLUSION: Frameless stereotactic accuracy is increased by using high-field iMRI compared with standard preoperative imaging.

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Late infections after dynamic stabilization of the lumbar spine with Dynesys

Late infections after dynamic stabilization of the lumbar spine with Dynesys

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.

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The intracranial volume pressure response in increased intracranial pressure patients

The intracranial volume pressure response in increased intracranial pressure patients- Part 1

Acta Neurochir (2012) 154:2271–2275

The intracranial pressure (ICP) is usually continuously monitored in the management of patients with increased ICP. The aim of this study was to discover a mathematic equation to express the intracranial pressure– volume (P–V) curve and a single indicator to reflect the status of the curve.

Methods Patients with severe brain damage who had bilateral external ventricular drainage (EVD) from December 2008 to February 2010 were included in this study. The EVD was used as drainage of CSF and ICP monitor. The successive volume pressure response values were obtained by successive drainage of CSF from ICP 20–25 to 10 mmHg. Parabolic, exponential, and linear regression models were designed to have a single parameter as the indicator to determine the P–V curves.

Results The mean of parameter “a” in the exponential equation is 1.473±0.054; in the parabolic equation, it is 0.332±0.061; and in the linear equation, it is 1.717±0.209. All regression equations of P–V curves had statistical significance (p<0.005). Parabolic and exponential equations are closer to the original ICP curve than linear equation (p< 0.005). There is no statistically significant difference between parabolic and exponential regressions.

Conclusions The P–V curve can be expressed with linear, parabolic, and exponential regression models in increased ICP patients. The parabolic and exponential equations are more accurate methods to represent the P–V curve. The single parameter in the three regression equations can be compared in different conditions of one patient in clinical practice.

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The Naso-Axial Line: A New Method of Accurately Predicting the Inferior Limit of the Endoscopic Endonasal Approach to the Craniovertebral Junction

The Naso-Axial Line- A New Method of Accurately Predicting the Inferior Limit of the Endoscopic Endonasal Approach to the Craniovertebral Junction

Neurosurgery 71[ONS Suppl 2]:ons308–ons314, 2012

The endoscopic endonasal approach (EEA) has developed as an emerging surgical corridor to the craniovertebral junction (CVJ). In addition to understanding its indications and surgical anatomy, the ability to predict its inferior limit is vital for optimal surgical planning.

OBJECTIVE: To develop a method that accurately predicts the inferior limit of the EEA on the CVJ radiologically and to compare this with other currently used methods.

METHODS: Predissection computerized tomographic scans of 9 cadaver heads were used to delineate a novel line, the naso-axial line (NAxL), to predict the inferior EEA limit on the upper cervical spine. A previously described method with the use of the nasopalatine line (NPL or Kassam line) was also used. On computerized tomographic scans obtained following dissection of the EEA, the predicted inferior limits were compared with the actual extent of dissection.

RESULTS: The postdissection inferior EEA limit ranged from the dens tip to the upper half of the C2 body, which matched the limit predicted by NAxL, with no statistically significant difference between them. In contrast to the NAxL, the NPL predicted a significantly lower EEA limit (P , .001), ranging from the lower half of the C2 body to the superior end plate of C3.

CONCLUSION: The novel NAxL more accurately predicts the inferior limit of the EEA than the NPL. This method, which can be easily used on preoperative sagittal scans, accounts for variations in patients’ anatomy and can aid surgeons in the assessment of the EEA to address caudal CVJ pathology.

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Safety and Efficacy of Intraoperative Angiography in Craniotomies for Cerebral Aneurysms and Arteriovenous Malformations

Intraoperative angiography in aneurysms surgery

Neurosurgery 71:1162–1169, 2012

In an era of indocyanine angiography, the routine use of intraoperative angiography (IOA) in the surgical treatment of aneurysms and vascular malformations is controversial.

OBJECTIVE: To retrospectively assess the safety and efficacy of IOA and to determine predictors of surgical revision.

METHODS: Between 2003 and 2011, IOA was performed during surgical treatment of 976 aneurysms, 101 arteriovenous malformations (AVMs), and 16 arteriovenous fistulas.

RESULTS: In 80 of 976 aneurysms (8.2%), IOA prompted clip repositioning. The reason for readjustment was residual aneurysm in 54.7%, parent vessel occlusion in 42.9%, and both in 2.4% of cases. In multivariate analysis, increasing aneurysm size (P,.001), ruptured aneurysm (P,.001), and increasing number of vessels injected (P,.001) were strong predictors of clip readjustment. There was a strong trend for posterior circulation aneurysm location to predict clip repositioning (P = .06). IOA revealed residual nidus/ fistula requiring further intervention in 9 of 101 AVMs (8.9%) and 3 of 16 arteriovenous fistulas (18.8%). Of 9 AVMs requiring a surgical revision, 2 (22.2%) were Spetzler-Martin grade II, 5 (55.6%) were grade III, and 2 (22.2%) were grade IV. Mean Spetzler-Martin grade was 3.0 in AVMs requiring surgical revision compared with 2.3 in those not requiring revision (P = .05). IOA-related complications were all transient or minor and occurred in 0.99% of patients; none resulted in permanent morbidity.

CONCLUSION: IOA remains a valuable tool in the surgical treatment of brain vascular abnormalities, guiding surgical re-exploration in >8% of cases. Easy access to an angiographer and routine use of IOA are important factors contributing to procedural safety and efficacy.

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Shunting with gravitational valves—can adjustments end the era of revisions for overdrainage-related events?

overshunting with gravitational valves—can adjustments end the era of revisions for overdrainage-related events?

J Neurosurg 117:1197–1204, 2012

Overdrainage of CSF remains an unsolved problem in shunt therapy. The aim of the present study was to evaluate treatment options on overdrainage-related events enabled by the new generation of adjustable gravityassisted valves.

Methods. The authors retrospectively studied the clinical course of 250 consecutive adult patients with various etiologies of hydrocephalus after shunt insertion for different signs and symptoms of overdrainage. Primary and secondary overdrainage were differentiated. The authors correlated the incidence of overdrainage with etiology of hydrocephalus, opening valve pressure, and patient parameters such as weight and size. Depending on the severity of overdrainage, they elevated the opening pressure, and follow-up was performed until overdrainage was resolved.

Results. The authors found 39 cases (15.6%) involving overdrainage-related problems—23 primary and 16 secondary overdrainage. The median follow-up period in these 39 patients was 2.1 years. There was no correlation between the incidence of overdrainage and any of the following factors: sex, age, size, or weight of the patients. There was also no statistical significance among the different etiologies of hydrocephalus, with the exception of congenital hydrocephalus. All of the “complications” could be resolved by readjusting the opening pressure of the valve in one or multiple steps, avoiding further operations.

Conclusions. Modern adjustable and gravity-assisted valves enable surgeons to set the opening pressure relatively low to avoid underdrainage without significantly raising the incidence of overdrainage and to treat overdrainagerelated clinical and radiological complications without surgical intervention.

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Ultrasonographic quantification of spinal cord and dural pulsations during cervical laminoplasty in patients with compressive myelopathy

Eur Spine J (2012) 21:2450–2455

Pulsatile movements of the dura mater have been interpreted as a sign that the cord is free within the subarachnoid space, with no extrinsic compression. However, the association between restoration of pulsation and adequate decompression of the spinal cord has not been established. The present study investigated the relationship between the extent of spinal cord decompression and spinal cord and dural pulsations based on quantitative analysis of intraoperative ultrasonography (US).

Methods Eighty-five consecutive patients (55 males, 30 females; mean age, 64 ± 13 years) who underwent cervical double-door laminoplasty to relieve compressive myelopathy were enrolled. Spinal cord decompression status was classified as: Type 1 (non-contact), the subarachnoid space was retained on the ventral side of the cord, Type 2 (contact and apart), the cord showed both contact with and separation from the anterior element of the cervical spine, or Type 3 (contact), the cord showed continuous contact with the anterior element of the cervical spine. Spinal cord and dura mater dynamics were quantitatively analyzed using automatic video-tracking software. Furthermore, the intensity of spinal and dural pulsation was compared with the recovery of motor function at 1 year after surgery as measured by increase in the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ).

Results Spinal cord pulsation amplitude ranged from 0.01 to 0.84 mm (mean 0.30 ± 0.16 mm) and dural pulsation amplitude ranged from 0.01 to 0.38 mm (mean 0.14 ± 0.08 mm). Average spinal cord pulsation amplitude in Type 2 patients was significantly larger than that in the other groups, whereas, average dural pulsation amplitudes were similar for all three groups. There was a significant correlation between spinal cord and dural pulsation amplitudes in Type 1 patients, but not in Type 2 or Type 3 patients. Type 3 patients showed a particularly poor correlation between spinal cord and dural pulsations. Spinal cord pulsation amplitude was moderately correlated with the recovery of motor function evaluated by JOACMEQ.

Conclusion The present results suggest that restoration of dural pulsation is not an adequate indicator of sufficient decompression of the spinal cord following a surgical procedure.

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Selective-Targeted Extra-Intracranial Bypass Surgery in Complex Middle Cerebral Artery Aneurysms: Correctly Identifying the Recipient Artery Using Indocyanine Green Videoangiography

Neurosurgery 71[ONS Suppl 2]:ons274–ons285, 2012

Treatment of complex middle cerebral artery (MCA) aneurysms often requires vessel sacrifice or prolonged temporary occlusion with extra- to intracranial (EC-IC) bypass to preserve perfusion. A crucial surgical step is the identification of the bypass recipient artery matching the distal territory of the involved vessel.

OBJECTIVE: To report about the feasibility and efficiency of an indocyanine green videoangiography (ICG-VA) assisted technique for identification of cortical recipient vessels to perform selective-targeted EC-IC bypass.

METHODS: The proposed technique is based on the analysis of differences in the timing of filling of M4 vessels seen on serial ICG-VAs. A delayed fluorescence can be visualized either primarily on a baseline ICG-VA or secondarily on an ICG-VA performed during temporary occlusion of the involved MCA branch. M4 branches presenting delayed fluorescence represent suitable bypass recipient arteries. We report 7 consecutive patients treated for complex MCA aneurysms with selective-targeted EC-IC bypass.

RESULTS: Application of the proposed technique permitted the correct identification of recipient arteries (cortical branches of the involved MCA segment) in all patients. The cortex distal to the occlusion filled concomitantly on ICG-VA at the end of surgery. All patients underwent successful treatment of the aneurysm, including a cortical bypass. There were no ischemic complications, and a favorable clinical outcome was achieved in all patients (modified Rankin Scale at follow-up # modified Rankin Scale preoperative).

CONCLUSION: The proposed ICG-VA-based technique enables reliable and accurate identification of the cortical recipient artery and eliminates the risk of erroneous revascularization of noninvolved territories.

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Clinical Application of Motor Pathway Mapping Using Diffusion Tensor Imaging Tractography and Intraoperative Direct Subcortical Stimulation in Cerebral Glioma Surgery

Neurosurgery 71:1170–1184, 2012

Glioma surgery in eloquent areas remains a challenge because of the risk of postoperative motor deficits.

OBJECTIVE: To prospectively evaluate the efficiency of using a combination of diffusion tensor imaging (DTI) tractography functional neuronavigation and direct subcortical stimulation (DsCS) to yield a maximally safe resection of cerebral glioma in eloquent areas.

METHODS: A prospective cohort study was conducted in 58 subjects with an initial diagnosis of primary cerebral glioma within or adjacent to the pyramidal tract (PT). The white matter beneath the resection cavity was stimulated along the PT, which was visualized with DTI tractography. The intercept between the PT border and DsCS site was measured. The sensitivity and specificity of DTI tractography for PT mapping were evaluated. The efficiency of the combined use of both techniques on motor function preservation was assessed.

RESULTS: Postoperative analysis showed gross total resection in 40 patients (69.0%). Seventeen patients (29.3%) experienced postoperative worsening; 1-month motor deficit was observed in 6 subjects (10.3%). DsCS verified a high concordance rate with DTI tractography for PT mapping. The sensitivity and specificity of DTI were 92.6% and 93.2%, respectively. The intercepts between positive DsCS sites and imaged PTs were 2.0 to 14.7 mm (5.262.2 mm). The 6-month Karnofsky Performance Scale scores in 50 postoperative subjects were significantly increased compared with their preoperative scores.

CONCLUSION: DTI tractography is effective but not completely reliable in delineating the descending motor pathways. Integration of DTI and DsCS favors patient-specific surgery for cerebral glioma in eloquent areas.

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Higher incidence of epilepsy in meningiomas located on the premotor cortex: a voxel-wise statistical analysis

Acta Neurochir (2012) 154:2241–2249

A substantial number of patients with brain tumors develop recurrent seizures, known as tumorassociated epilepsy. It is important to identify specific subgroups of brain tumor patients with higher incidences of epilepsy because a meta-analysis failed to certify the effectiveness of prophylactic anti-epileptic drugs (AEDs) to abort tumor-associated epilepsy as a whole.

Methods To investigate the relationship between tumor location and incidence of epilepsy, we performed voxel-wise comparison between 3D MRI scans obtained from patients with meningioma-associated epilepsy and those from control patients using spatial normalization techniques on neuroimaging data. Variables such as age, tumor size, the degree of edema, and pathological diagnosis were also compared between the two groups.

Results Our results showed the highest incidence of epilepsy when the tumor was located on the premotor cortex in the frontal lobe (Z-scores >2.0, Liebermeister’s quasi-exact test). The stepwise multiple regression analysis on the clinical data revealed that the tumor diameter (p<0.001) and the patient’s age (p=0.024) were positive and negative predictors, respectively, for the onset of epilepsy.

Conclusions The incidence of epilepsy was higher in meningiomas located on the premotor cortex than on the other cortex. Larger volume also contributed to the onset of epilepsy. We suggest that variations of epilepsy incidence dependent on tumor characteristics can be considered when treating tumor-associated epilepsy.

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Augmented Autologous Pericranium Duraplasty in 100 Posterior Fossa Surgeries—A Retrospective Case Series

Neurosurgery 71[ONS Suppl 2]:ons302–ons307, 2012

Primary closure of the dura in posterior fossa (p-fossa) surgeries is technically difficult and usually requires the use of a dural substitute. A variety of substitutes are currently available and data suggest that autologous materials are preferred in comparison with nonautologous substitutes.

OBJECTIVE: To report our experience using locally harvested autologous pericranium as a dural substitute in patients who underwent p-fossa surgeries.

METHODS: Retrospective analysis of patients who had undergone p-fossa craniotomies between 2005 and 2011. All patients received locally harvested autologous pericranium for duraplasty augmented with a dural sealant. Data were reviewed for complications including: surgical site infection, meningitis, cerebrospinal fluid leak, the radiographic formation of a pseudomeningocele, and any new neurological symptoms related to the incision or repair.

RESULTS: One hundred patients were identified. Indications for surgery included tumor, vascular lesions, or hemorrhage requiring surgical intervention, symptomatic Chiari I malformation, microvascular decompression for trigeminal neuralgia, and trauma requiring surgical decompression. The complication rate was 1% with 1 patient developing an nonsteroidal anti-inflammatory drug-induced aseptic meningitis and graft dehiscence requiring surgical revision.

CONCLUSION: Autologous pericranium with dural sealant augmentation is an effective way to repair the durotomy in p-fossa surgeries. To the best of our knowledge, this is currently the largest study using this technique in the adult neurosurgical literature. Our results report a much lower rate of complications in comparison with other duraplasty studies.

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Cerebellar Arteriovenous Malformations: Anatomic Subtypes, Surgical Results, and Increased Predictive Accuracy of the Supplementary Grading System

Neurosurgery 71:1111–1124, 2012

Anatomic diversity among cerebellar arteriovenous malformations (AVMs) calls for a classification that is intuitive and surgically informative. Selection tools like the Spetzler-Martin grading system are designed to work best with cerebral AVMs but have shortcomings with cerebellar AVMs.

OBJECTIVE: To define subtypes of cerebellar AVMs that clarify anatomy and surgical management, to determine results according to subtypes, and to compare predictive accuracies of the Spetzler-Martin and supplementary systems.

METHODS: From a consecutive surgical series of 500 patients, 60 had cerebellar AVMs, 39 had brainstem AVMs and were excluded, and 401 had cerebral AVMs.

RESULTS: Cerebellar AVM subtypes were as follows: 18 vermian, 13 suboccipital, 12 tentorial, 12 petrosal, and 5 tonsillar. Patients with tonsillar and tentorial AVMs fared best. Cerebellar AVMs presented with hemorrhage more than cerebral AVMs (P,.001). Cerebellar AVMs were more likely to drain deep (P = .04) and less likely to be eloquent (P,.001). The predictive accuracy of the supplementary grade was better than that of the Spetzler-Martin grade with cerebellar AVMs (areas under the receiver-operating characteristic curve, 0.74 and 0.59, respectively). The predictive accuracy of the supplementary system was consistent for cerebral and cerebellar AVMs, whereas that of the Spetzler-Martin system was greater with cerebral AVMs.

CONCLUSION: Patients with cerebellar AVMs present with hemorrhage more often than patients with cerebral AVMs, justifying an aggressive treatment posture. The supplementary system is better than the Spetzler-Martin system at predicting outcomes after cerebellar AVM resection. Key components of the Spetzler-Martin system such as venous drainage and eloquence are distorted by cerebellar anatomy in ways that components of the supplementary system are not.

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Low-grade glioma surgery in eloquent areas

J Neurosurg 117:1039–1052, 2012

A growing number of published studies have recently demonstrated the role of resection in overall survival (OS) for patients with gliomas. In this retrospective study, the authors objectively investigated the role of the extent of resection (EOR) in OS in patients with low-grade gliomas (LGGs).

Methods. Between 1998 and 2011, 190 patients underwent surgery for LGGs. All surgical procedures were conducted under corticosubcortical stimulation. The EOR was established by analyzing the pre- and postoperative volumes of the gliomas on T2- weighted MRI studies. The difference between the preoperative tumor volumes was also investigated by measuring the volumetric difference between the T2- and T1-weighted MRI images (DVT2T1) to evaluate how the diffusive tumor-growing pattern affected the EOR achieved.

Results. The median preoperative tumor volume was 55 cm3, and in almost half of the patients the EOR was greater than 90%. In this study, patients with an EOR of 90% or greater had an estimated 5-year OS rate of 93%, those with EOR between 70% and 89% had a 5-year OS rate of 84%, and those with EOR less than 70% had a 5-year OS rate of 41% (p < 0.001). New postoperative deficits were noted in 43.7% of cases, while permanent deficits occurred in 3.16% of cases. There were 41 deaths (21.6%), and the median follow-up was 4.7 years. A further volumetric analysis was also conducted to compare 2 different intraoperative protocols (Series 1 [intraoperative electrical stimulation alone] vs Series 2 [intraoperative stimulation plus overlap of functional MRI/fiber tracking diffusion tensor imaging data on a neuronavigation system]). Patients in Series 1 had a median EOR of 77%, while those in Series 2 had a median EOR of 90% (p = 0.0001). Multivariate analysis showed that OS is influenced not only by EOR (p = 0.001) but also by age (p = 0.003), histological subtype (p = 0.005), and the DVT2T1 value (p < 0.0001). Progression-free survival is similarly influenced by histological subtype (fibrillary astrocytoma, p = 0.003), EOR (p < 0.0001), and DVT2T1 value (p < 0.0001), as is malignant progression– free survival (p = 0.003, p < 0.0001, and p < 0.0001, respectively). Finally, the study shows that the higher the DVT2T1 value, the less extensive the currently possible resection, highlighting an apparent correlation between the DVT2T1 value itself and EOR (p < 0.0001).

Conclusions. The EOR and the DVT2T1 values are the strongest independent predictors in improving OS as well as in delaying tumor progression and malignant transformation. Furthermore, the DVT2T1 value may be useful as a predictive index for EOR. Finally, due to intraoperative corticosubcortical mapping and the overlap of functional data on the neuronavigation system, major resection is possible with an acceptable risk and a significant increase in expected OS.

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Brain Tumor Surgery With 3-Dimensional Surface Navigation

Neurosurgery 71[ONS Suppl 2]:ons286–ons295, 2012

Precise lesion localization is necessary for neurosurgical procedures not only during the operative approach, but also during the preoperative planning phase. OBJECTIVE: To evaluate the advantages of 3-dimensional (3-D) brain surface visualization over conventional 2-dimensional (2-D) magnetic resonance images for surgical planning and intraoperative guidance in brain tumor surgery.

METHODS: Preoperative 3-D brain surface visualization was performed with neurosurgical planning software in 77 cases (58 gliomas, 7 cavernomas, 6 meningiomas, and 6 metastasis). Direct intraoperative navigation on the 3-D brain surface was additionally performed in the last 20 cases with a neurosurgical navigation system. For brain surface reconstruction, patient-specific anatomy was obtained from MR imaging and brain volume was extracted with skull stripping or watershed algorithms, respectively. Threedimensional visualization was performed by direct volume rendering in both systems. To assess the value of 3-D brain surface visualization for topographic lesion localization, a multiple-choice test was developed. To assess accuracy and reliability of 3-D brain surface visualization for intraoperative orientation, we topographically correlated superficial vessels and gyral anatomy on 3-D brain models with intraoperative images.

RESULTS: The rate of correct lesion localization with 3-D was significantly higher (P = .001, x2), while being significantly less time consuming (P , .001, x2) compared with 2-D images. Intraoperatively, visual correlation was found between the 3-D images, superficial vessels, and gyral anatomy.

CONCLUSION: The proposed method of 3-D brain surface visualization is fast, clinically reliable for preoperative anatomic lesion localization and patient-specific planning, and, together with navigation, improves intraoperative orientation in brain tumor surgery and is relatively independent of brain shift.

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Interhemispheric approach for tuberculum sellae meningiomas

J Neurosurg 117:1013–1021, 2012

The objective of this study was to evaluate the ophthalmological outcome, nonvisual morbidity, and surgical complications after tuberculum sellae meningioma (TSM) removal using a superior interhemispheric approach.

Methods. In the last decade, 20 consecutive patients with TSM underwent operations using the superior interhemispheric approach. Visual acuity, visual field, and ocular fundus examination were assessed both preoperatively and 6-months postoperatively. Nonvisual morbidity was determined at an early postoperative period and at 6 months based on assessment of the Karnofsky Performance Scale score, leakage of CSF, endocrinological status, and olfactory function, which was assessed using a visual analog scale (VAS). The potential brain injury related to the approach was assessed by MRI at 6 months. Magnetic resonance imaging was then performed yearly to detect a recurrence.
The mean follow up was 56.3 ± 34 months.

Results. The primary presenting symptom for diagnosis of TSM in 20 patients (female:male ratio of 6.6:1, mean age 59.1 ± 11.1 years) was visual disturbance in 12 patients (60%), headache in 4 (20%), cognitive alteration in 1 (5%), epilepsy in 2 (10%), and accidental in 1 (5%). In a total of 40 eyes, 17 eyes in 11 patients presented with preoperative deterioration of visual acuity. Postoperatively, the visual acuity improved in 13 eyes in 8 patients (72.8%), remained unchanged in 3 eyes in 2 patients (18.2%) and deteriorated in 1 patient (9%). The nonvisual morbidity included olfactory deterioration in 7 patients (35%), and panhypopituitarism in 1 patient (5%). No patients experienced a CSF leak. The impact of olfactory deterioration on the quality of life, as estimated by a VAS score (range 0–10), was a mean of 5.7 ± 2.2 (95% CI 4.1–7.3). On the follow-up MRI, no additional lesions or recurrences were observed on the medial aspect of the frontal lobe along the surgical corridor.

Conclusions. The superior interhemispheric approach appears to be effective in resolving the problem of visual deterioration due to a TSM, without inducing surgical injury on the brain surface along the surgical corridor. Olfactory deterioration remained the challenging predominant nonvisual morbidity using this approach.

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Selective-Targeted Extra-Intracranial Bypass Surgery in Complex Middle Cerebral Artery Aneurysms: Correctly Identifying the Recipient Artery Using Indocyanine Green Videoangiography

Neurosurgery 71[ONS Suppl 2]:ons274–ons285, 2012

Treatment of complex middle cerebral artery (MCA) aneurysms often requires vessel sacrifice or prolonged temporary occlusion with extra- to intracranial (EC-IC) bypass to preserve perfusion. A crucial surgical step is the identification of the bypass recipient artery matching the distal territory of the involved vessel.

OBJECTIVE: To report about the feasibility and efficiency of an indocyanine green videoangiography (ICG-VA) assisted technique for identification of cortical recipient vessels to perform selective-targeted EC-IC bypass.

METHODS: The proposed technique is based on the analysis of differences in the timing of filling of M4 vessels seen on serial ICG-VAs. A delayed fluorescence can be visualized either primarily on a baseline ICG-VA or secondarily on an ICG-VA performed during temporary occlusion of the involved MCA branch. M4 branches presenting delayed fluorescence represent suitable bypass recipient arteries. We report 7 consecutive patients treated for complex MCA aneurysms with selective-targeted EC-IC bypass.

RESULTS: Application of the proposed technique permitted the correct identification of recipient arteries (cortical branches of the involved MCA segment) in all patients. The cortex distal to the occlusion filled concomitantly on ICG-VA at the end of surgery. All patients underwent successful treatment of the aneurysm, including a cortical bypass. There were no ischemic complications, and a favorable clinical outcome was achieved in all patients (modified Rankin Scale at follow-up # modified Rankin Scale preoperative).

CONCLUSION: The proposed ICG-VA-based technique enables reliable and accurate identification of the cortical recipient artery and eliminates the risk of erroneous revascularization of noninvolved territories.

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