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Navigated Transcranial Magnetic Stimulation and Functional Magnetic Resonance Imaging: Advanced Adjuncts in Preoperative Planning for Central Region Tumors

Neurosurgery 68:1317–1325, 2011 DOI: 10.1227/NEU.0b013e31820b528c

Tumor resection in the vicinity of the motor cortex poses a challenge to all neurosurgeons. For preoperative assessment of eloquent cortical areas, functional magnetic resonance imaging (fMRI) is used, whereas intraoperatively, direct cortical stimulation (DCS) is performed. Navigated transcranial magnetic stimulation (nTMS) is comparable to DCS in activating cortical pyramidal neurons.

OBJECTIVE: To evaluate the reliability of nTMS compared with fMRI and DCS for preoperative resection planning of centrally located tumors.

METHODS: In a prospective series, 11 patients (ages, 20-63 years; mean, 41.9 ± 14.9 years, 2 women) with tumors located in or adjacent to the motor cortex were evaluated for surgery. fMRI and nTMS were applied for preoperative assessment of the extent of tumor resection. A 3-dimensional anatomic data set with superimposed fMRI data was integrated in the eXimia Navigated Brain Stimulation station for ensuing motor cortex mapping by nTMS. Responses from nTMS were evaluated by electromyographic response. During surgery, the coordinates of each DCS site were unambiguously defined and integrated into neuronavigation. A post hoc comparison of the coordinates of nTMS, fMRI, and DCS was performed.

RESULTS: Distances from nTMS to DCS (10.5 ± 5.67 mm) were significantly smaller than those from fMRI to DCS (15.0 ± 7.6 mm).

CONCLUSION: nTMS anticipates information usually only enabled by DCS and therefore allows surgical planning in eloquent cortex surgery.

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Morbidity of Ventricular Cerebrospinal Fluid Shunt Surgery in Adults: An 8-Year Study

Neurosurgery 68:985–995, 2011 DOI: 10.1227/NEU.0b013e318208f36

Cerebrospinal fluid (CSF) shunt procedures have dramatically reduced the morbidity and mortality rates associated with hydrocephalus. However, despite improvements in materials, devices, and surgical techniques, shunt failure and complications remain common and may require multiple surgical procedures.

OBJECTIVE: To evaluate CSF shunt complication incidence and factors that may be associated with increased shunt dysfunction and infection rates in adults.

METHODS: From January 1999 to December 2006, we conducted a prospective surveillance program for all neurosurgical procedures including reoperations and infections. Patients undergoing CSF shunt placement were retrospectively identified among patients labeled in the database as having a shunt as a primary or secondary intervention. Revisions of shunts implanted in another hospital or before the study period were excluded, as well as lumbo- or cyst-peritoneal shunts. Shunt complications were classified as mechanical dysfunction or infection. Follow-up was at least 2 years. Potential risk factors were evaluated using log-rank tests and stepwise Cox regression models.

RESULTS: During the 8-year surveillance period, a total of 14 275 patients underwent neurosurgical procedures, including 839 who underwent shunt placement. One hundred nineteen patients were excluded, leaving 720 study patients. Mechanical dysfunction occurred in 124 patients (17.2%) and shunt infection in 44 patients (6.1%). These 168 patients required 375 reoperations. Risk factors for mechanical dysfunction were atrial shunt, greater number of previous external ventriculostomies, and male sex; risk factors for shunt infection were previous CSF leak, previous revisions for dysfunction, surgical incision after 10 AM, and longer operating time.

CONCLUSION: Shunt surgery still carries a high morbidity rate, with a mean of 2.2 reoperations per patient in 23.3% of patients. Our risk-factor data suggest methods for decreasing shunt-related morbidity, including peritoneal routing whenever possible and special attention to preventing CSF leaks after craniotomy or external ventriculostomy.

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Pineal region tumors: an optimal approach for simultaneous endoscopic third ventriculostomy and biopsy

Neurosurg Focus 30 (4):E3, 2011. DOI: 10.3171/2011.2.FOCUS10301

Simultaneous endoscopic third ventriculostomy (ETV) and tumor biopsy is a widely accepted therapeutic and diagnostic procedure for patients with noncommunicating hydrocephalus secondary to a pineal region tumor. Multiple approaches have been advocated, including the use of a steerable fiberoptic or rigid lens endoscope via 1 or 2 trajectories. However, the optimal approach has not been established based on the individual anatomical characteristics of the patient.

 Methods. A retrospective review of patients undergoing simultaneous ETV and tumor biopsy was undertaken. Preoperative MR images were examined to measure the width of the anterior third ventricle and maximal diameters of the tumor, Monro foramen (right), and massa intermedia. The distances between the tumor and massa intermedia, tumor and anterior commissure, midbrain and massa intermedia, and the dorsum sella and anterior commissure were also recorded. Single and dual trajectory approaches were compared using paired t-tests for each parameter.

Results. Over an 8-year interval, 15 patients underwent simultaneous ETV and tumor management. These patients ranged from 6 to 71 years of age (mean 36.7 years); 5 were younger than 18 years of age. Seven were treated using a dual trajectory approach, and 8 were treated using a single trajectory approach. All cases were completed without complications or the need for an additional CSF diversionary procedure within 6 months. The diagnostic yield at biopsy was 86.7%. There were no statistically significant differences between the single and dual trajectory groups for the measured parameters. However, the dual trajectory group demonstrated a larger anterior third ventricular diameter (1.43 vs 1.21 cm, p = 0.29). The single trajectory group trended toward a smaller tumor– anterior commissure interval (2.23 vs 2.51 cm, p = 0.24) and a larger dorsum sella–anterior commissure distance (1.67 vs 1.49 cm, p = 0.28).

Conclusions. These data confirm the safety and diagnostic efficacy of simultaneous ETV and biopsy for tumors of the pineal region. Although no statistically significant differences were seen in the authors’ recorded measurements, several trends suggest a role for a tailored approach to selecting a single or dual trajectory approach when using a rigid endoscope

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Posterior ring apophysis separation combined with lumbar disc herniation in adults: a 10-year experience in the surgical management of 87 cases

J Neurosurg Spine 14:475–483, 2011 475. DOI: 10.3171/2010.11.SPINE10392

The association of posterior ring apophysis separation (PRAS) with lumbar disc herniation (LDH) is uncommon and represents a true subgroup of disc herniation mainly seen in the adolescent population. The objective of this study was to describe a decade of experience in the care of adult patients with PRAS with LDH, giving particular attention to its diagnosis, surgical treatment, and outcome.

Methods. This retrospective study focuses on a case series of adult patients with PRAS associated with LDH who underwent surgery for lumbar disc disease in the author’s neurosurgical department between 1999 and 2008. Posterior ring apophysis separation was diagnosed in 87 (5.35%) of 1625 patients surgically treated for LDH; these patients made up the PRAS group. During a 6-month period in 2005, LDH without PRAS was diagnosed in 89 consecutive patients at the same facility; these patients constituted the control group. Presenting symptoms, physical examination findings, and preoperative imaging results were obtained from medical records. Immediate operative results were assessed, as were complications, long-term outcome, and the need for repeat surgery.

Results. This study is the first to document the distinguishing features between adult patients with and those without PRAS. The difference in average age was statistically significant (p < 0.001) between the study group (36.22 years) and the control group (44.30 years), as was the incidence of male patients (86.20% vs 71.91%, p = 0.020), incidence of military patients (74.71% vs 57.30%, p = 0.015), average duration of symptoms (16.13 vs 8.4 months, p = 0.016), and incidence of reactive scoliosis (19.54% vs 4.49%, p = 0.002). The most common anatomical location of disc herniation in the PRAS group was L5–S1 (51.72%) versus L4–L5 (53.93%) in the control group (p = 0.017). In terms of previous injury, motor deficits, back and/or leg pain, lateral or central location of LDH, mean anteroposterior diameter of disc herniation, hard or soft discs, and surgical complications, there was no statistical difference between the 2 patient groups. Similarly, there was no difference in recurrence rates and clinical outcomes between the patients with or without PRAS.

Conclusions. Posterior ring apophysis separation with LDH is probably more common in adults than is generally recognized. It must be suspected when young male patients with persistent sciatic scoliosis and no history of injury show signs of calcified LDH. Computed tomography scanning with sagittal reconstructions is the procedure of choice for diagnosing. The L5–S1 intervertebral disc level is most commonly affected, especially the superior endplate of S-1. This condition needs more extensive surgical exposure and resection to relieve the nerve impingement. The occurrence of an apophyseal lesion was not associated with recurrent disc herniation or a fair outcome.

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Fate of Clots in Patients With Subarachnoid Hemorrhage After Different Surgical Treatment Modality: A Comparison Between Surgical Clipping and Guglielmi Detachable Coil Embolization

Neurosurgery 68:966–973, 2011 DOI: 10.1227/NEU.0b013e318208f1ba 

Subarachnoid clot is important in the development of delayed vasospasm after subarachnoid hemorrhage (SAH).

OBJECTIVE: To compare the clearance of subarachnoid clot and the incidence of symptomatic vasospasm in surgical clipping and embolization with Guglielmi detachable coils for aneurysmal SAH.

METHODS: The subjects were 115 patients with Fisher group 3 aneurysmal SAH on computed tomography scan at admission whose aneurysm was treated by surgical clipping (clip group; n = 86) or Guglielmi detachable coil embolization (coil group; n = 29) within 72 hours of ictus. Software-based volumetric quantification of the subarachnoid clot was performed, and the amount of hemoglobin in drained cerebrospinal fluid was measured.

RESULTS: Clearance of the subarachnoid clot on the computed tomography scan was rapid in the clip group until the day after the operation but slow in the coil group (58.9% removed vs 27.8% removed; P = .008). However, postoperative clearance of the clot occurred more rapidly in the coil group. Reduction of the clot until days 3 through 5 did not differ significantly between the 2 groups (72.9% removed vs 75.2% removed). The amount of hemoglobin in the clip group was . 0.8 g/d until day 3 and then gradually decreased (n = 15), but hemoglobin in the coil group remained at . 0.8 g/d until day 5 (n = 17). The incidence of symptomatic vasospasm did not differ between the groups.

CONCLUSION: Subarachnoid clot can be removed directly during surgical clipping, which is not possible with endovascular treatment. However, the percentage reduction of the clot on days 3 through 5 did not differ between the 2 groups.

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Transsphenoidal pseudocapsule-based extracapsular resection for pituitary adenomas

Acta Neurochir (2011) 153:799–806. DOI 10.1007/s00701-011-0961-1

In the past several years, increasing attention has been paid to the utility of a pseudocapsule in transphenoidal surgery for pituitary adenomas. However, prior studies focused more on the histological structure of the pseudocapsule and surgical technique. The objective of this study was to evaluate the overall therapeutic effectiveness of transsphenoidal pseudocapsule-based extracapsular resection for pituitary adenomas.

Methods Between January 2004 and October 2007, 78 patients with pituitary adenomas underwent transsphenoidal pseudocapsule-based extracapsular removal surgery (extracapsular resection group, ER group). During the same period, 64 patients underwent transsphenoidal intracapsular resection operations (intracapsular resection group, IR group).

Results Complete resection rates were achieved in 90.6%, 84.6% and 65.5%, 52.6% of modified Hardy types II and III in the ER and IR groups, showing a significant difference (both P<0.05). Statistical significance in the remission rates was also found between the two groups with modified Hardy types II and III, respectively (both P<0.05). Complications occurred in 29.5% of the ER group and 26.6% of the IR group, with no difference between groups (P>0.05). The recurrence rate of the ER group (2.56%) was lower than that of the IR group (14.06%).

Conclusion The transsphenoidal pseudocapsule-based extracapsular resection approach provides a more effective and safe alternative compared to the traditional intracapsular one because of its higher tumor removal and remission rates, and lower recurrence rate.

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Endoscopic Third Ventriculostomy for the Management of Chiari I and Related Hydrocephalus: Outcome and Pathogenetic Implications

Neurosurgery 68:950–956, 2011 DOI: 10.1227/NEU.0b013e318208f1f3

Hydrocephalus affects 7% to 10% of patients with Chiari I malformation (CIM). It can be successfully treated by endoscopic third ventriculostomy (ETV), possibly improving related CIM and syringomyelia.

OBJECTIVE: To confirm the effectiveness of ETV in the management of Chiari-related hydrocephalus and symptoms and to estimate the posterior cranial fossa volume (PCFV) to find the possible reasons for the success or failure of ETV.

METHODS: Fifteen patients (11 children and 4 adults) underwent ETV for hydrocephalus associated with CIM (syringomyelia was present in 6 patients). Preoperative PCFV, posterior fossa brain volume (PFBV), and PFBV/PCFV ratio were calculated in the last 12 patients in the series by a magnetic resonance imaging–based computerized method.

RESULTS: All patients had symptomatic hydrocephalus (mean third ventricle diameter, 14.1 mm). Mean tonsillar ectopia was 12.7 mm. Postoperatively, hydrocephalus symptoms improved in all cases (mean third ventricle diameter, 8.3 mm); signs and symptoms of CIM and syringomyelia resolved or improved in all patients, although the malformation remained radiologically stable in half of the patients (postoperative mean tonsillar ectopia, 8.8 mm). There were no remarkable differences between cases and controls with regard to PCFV and PFBV. The PFBV/PCFV ratio was comparable in pediatric cases and controls but not among adult patients, suggesting a PCF overcrowding in the controls.

CONCLUSION: ETV is an effective treatment for hydrocephalus associated with CIM. It is successful in improving CIM and syringomyelia in patients with no overcrowding (mainly in children) or with reversible overcrowding of the PCF (mainly in adults).

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Neuroendoscopic biopsy of ventricular tumors: a multicentric experience

Neurosurg Focus 30 (4):E2, 2011. DOI: 10.3171/2011.1.FOCUS10326

Although neuroendoscopic biopsy is routinely performed, the safety and validity of this procedure has been studied only in small numbers of patients in single-center reports. The Section of Neuroendoscopy of the Italian Neurosurgical Society invited some of its members to review their own experience, gathering a sufficient number of cases for a wide analysis.

Methods. Retrospective data were collected by 7 centers routinely performing neuroendoscopic biopsies over a period of 10 years. Sixty patients with newly diagnosed intraventricular and paraventricular tumors were included. No patient harboring a colloid cyst was included. Data regarding clinical presentation, neuroimaging findings, operative techniques, pathological diagnosis, postoperative complications, and subsequent therapy were analyzed.

Results. In all patients, a neuroendoscopic tumor biopsy was performed. In 38 patients (64%), obstructive hydrocephalus was present. In addition to the tumor biopsy, 32 patients (53%) underwent endoscopic third ventriculostomy (ETV), and 7 (12%) underwent septum pellucidotomy. Only 2 patients required a ventriculoperitoneal shunt shortly after the endoscopy procedure because ETV was not feasible. The major complication due to the endoscopy procedure was ventricular hemorrhage noted on the postoperative images in 8 cases (13%). Only 2 patients were symptomatic and required medical therapy. Infection occurred in only 1 case, and the other complications were all reversible. In no case did clinically significant sequelae affect the patient’s outcome. Tumor types ranged across the spectrum and included glioma (low- and high-grade [27%]), pure germinoma (15%), pineal parenchymal tumor (12%), primary neuroectodermal tumor (4%), lymphoma (9%), metastasis (4%), craniopharyngioma (6%), and other tumor types (13%). In 10% of patients, the pathological findings were inconclusive. According to diagnosis, specific therapy was performed in 35% of patients: 17% underwent microsurgical removal, and 18% underwent chemotherapy or radiotherapy.

Conclusions. This is one of the largest series confirming the safety and validity of the neuroendoscopic biopsy procedure. Complications were relatively low (about 13%), and they were all reversible. Neuroendoscopic biopsy provided meaningful pathological data in 90% of patients, making subsequent tumor therapy feasible. Cerebrospinal fluid pathways can be restored by ETV or septum pellucidotomy (65%) to control intracranial hypertension. In light of the results obtained, a neuroendoscopic biopsy should be considered a possible alternative to the stereotactic biopsy in the diagnosis and treatment of ventricular or paraventricular tumors. Furthermore, it could be the only surgical procedure necessary for the treatment of selected tumors.

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Anatomical triangles defining surgical routes to posterior inferior cerebellar artery aneurysms

J Neurosurg 114:1088–1094, 2011. DOI: 10.3171/2010.8.JNS10759

Surgical routes to posterior inferior cerebellar artery (PICA) aneurysms are opened between the vagus (cranial nerve [CN] X), accessory (CN XI), and hypoglossal (CN XII) nerves for safe clipping, but these routes have not been systematically defined. The authors describe 3 anatomical triangles and their relationships with PICA aneurysms, routes for surgical clipping, outcomes, and angiographically demonstrated anatomy.

Methods. The vagoaccesory triangle is defined by CN X superiorly, CN XI laterally, and the medulla medially. It is divided by CN XII into the suprahypoglossal triangle (above CN XII) and the infrahypoglossal triangle (below CN XII). From a consecutive surgical series of 71 PICA aneurysms in 70 patients, 51 aneurysms were analyzed using intraoperative photographs.

Results. Forty-three PICA aneurysms were located inside the vagoaccessory triangle and 8 were outside. Of the aneurysms inside the vagoaccessory triangle, 22 (51%) were exposed through the suprahypoglossal triangle and 19 (44%) through the infrahypoglossal triangle; 2 were between triangles. The lesions were evenly distributed between the anterior medullary (16 aneurysms), lateral medullary (19 aneurysms), and tonsillomedullary zones (16 aneurysms). Neurological and CN morbidity linked to aneurysms in the suprahypoglossal triangle was similar to that associated with aneurysms in the infrahypoglossal triangle, but no morbidity was associated with PICA aneurysms outside the vagoaccessory triangle. A distal PICA origin on angiography localized the aneurysm to the suprahypoglossal triangle in 71% of patients, and distal PICA aneurysms were localized to the infrahypoglossal triangle or outside the vagoaccessory triangle in 78% of patients.

Conclusions. The anatomical triangles and zones clarify the borders of operative corridors to PICA aneurysms and define the depth of dissection through the CNs. Deep dissection to aneurysms in the anterior medullary zone traverses CNs X, XI, and XII, whereas shallow dissection to aneurysms in the lateral medullary zone traverses CNs X and XI. Posterior inferior cerebellar artery aneurysms outside the vagoaccessory triangle are frequently distal and superficial to the lower CNs, and associated surgical morbidity is minimal. Angiography may preoperatively localize a PICA aneurysm’s triangular anatomy based on the distal PICA origin or distal aneurysm location.

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Parafalcine and midline arteriovenous malformations: surgical strategy, techniques, and outcomes

J Neurosurg 114:984–993, 2011. DOI: 10.3171/2010.12.JNS101297

Parafalcine arteriovenous malformations (AVMs) have a midline plane in common, but differ in their location (anterior, middle, or posterior) and depth (superficial or deep). Surgical management varies with AVM location and depth in terms of patient position, head position, craniotomy, and surgical approach. This study examined surgical strategies, patient outcomes, and regional factors influencing results.

Methods. Patients with AVMs located on the medial surface of the cerebral hemisphere were identified retrospectively from a consecutive, single-neurosurgeon series that is registered prospectively as part of the UCSF Brain Arteriovenous Malformation Study Project. During a 12-year period, 443 patients with AVMs were treated surgically. Of these 443 patients, 132 (30%) had parafalcine AVMs, which were distributed in zones as follows: superficialanterior, 25 (18.9%); superficial-middle, 26 (19.7%); superficial-posterior, 39 (29.5%); deep-anterior, 25 (18.9%); deep-posterior, 17 (12.9%). Five different surgical strategies were used depending on AVM zone.

Results. Complete AVM resection was achieved in 123 (93.2%) of 132 patients. Overall, neurological condition improved in 74 patients (56.1%) and remained unchanged in 41 patients (31.1%). Neurological condition deteriorated in 12 patients (9.1%), and 5 patients (3.8%) died. Patients with AVMs in the superficial-middle zone had the highest rate of neurological deterioration (26.9%).

Conclusions. Parafalcine AVMs lie on a midline surface that, when exposed with a bilateral craniotomy across the superior sagittal sinus and a wide opening of the interhemispheric fissure, makes them superficial. However, unlike convexity AVMs, which are approached perpendicularly, parafalcine AVMs are approached tangentially. Gravity retraction is useful with deeply located AVMs (those in the deep-anterior and deep-posterior zones), because it widens the interhemispheric fissure and accesses deep arterial feeding vessels from the anterior and posterior cerebral arteries. Surgical risks were increased in the superficial-middle zone, which is likely explained by the proximity of sensorimotor cortex. The authors’ regional classification of parafalcine AVMs may serve as a guide to surgical planning.

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Classification and Analysis of the Errors in Neuronavigation

Neurosurgery 68:1131–1143, 2011 DOI: 10.1227/NEU.0b013e318209cc45

There are many different types of errors in neuronavigation, and the reasons and results of these errors are complex. For a neurosurgeon using the neuronavigation system, it is important to have a clear understanding of when an error may occur, what the magnitude of it is, and how to avoid it or reduce its influence on the final application accuracy.

In this article, we classify all the errors into 2 groups according to the working principle of neuronavigation systems. The first group contains the errors caused by the differences between the anatomic structures in the images and that of the real patient, and the second group contains the errors occurring in transforming the position of surgical tools from the patient space to the image space. Each group is further divided into 2 subgroups.

We discuss 16 types of errors and classify each of them into one of the subgroups. The classification and analysis of these errors should help neurosurgeons understand the power and limits of neuronavigation systems and use them more properly.

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Individual Fiber Anatomy of the Subthalamic Region Revealed With Diffusion Tensor Imaging: A Concept to Identify the Deep Brain Stimulation Target for Tremor Suppression

Neurosurgery 68:1069–1076, 2011 DOI: 10.1227/NEU.0b013e31820a1a20

Deep brain stimulation (DBS) has been proven to alleviate tremor of various origins. Distinct regions have been targeted. One explanation for good clinical tremor control might be the involvement of the dentatorubrothalamic tract (DRT) as has been suggested in superficial (thalamic) and inferior (posterior subthalamic) target regions. Beyond a correlation with atlas data and the postmortem evaluation of patients treated with lesion surgery, proof for the involvement of DRT in tremor reduction in the living, the scope of this work, is elusive.

OBJECTIVE: To report a case of unilateral refractory tremor in tremor-dominant Parkinson disease treated with thalamic DBS.

METHODS: Preoperative diffusion tensor imaging (DTI) was performed. Correlation with individual DBS electrode contact locations was obtained through postoperative fusion of helical computed tomography (CT) data with DTI fiber tracking.

RESULTS: Tremor was alleviated effectively. An evaluation of the active electrode contact position revealed clear involvement of the DRT in tremor control. A closer evaluation of clinical effects and side effects revealed a highly detailed individual fiber map of the subthalamic region with DTI fiber tracking.

CONCLUSION: This is the first time the involvement of the DRT in tremor reduction through DBS has been shown in the living. The combination of DTI with postoperative CT and the evaluation of the electrophysiological environment of distinct electrode contacts led to an individual detailed fiber map and might be extrapolated to refined DTI-based targeting strategies in the future. Data acquisition for a larger study group is the topic of our ongoing research.

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Outcomes in pediatric patients with Chiari malformation Type I followed up without surgery

J Neurosurg Pediatrics 7:000–000, 2011.DOI: 10.3171/2011.1.PEDS10341

The natural history of untreated Chiari malformation Type I (CM-I) is poorly defined. The object of this study was to investigate outcomes in pediatric patients with CM-I who were followed up without surgical intervention.

Methods. The authors retrospectively reviewed 124 cases involving patients with CM-I who presented between July 1999 and July 2008 and were followed up without surgery. The patients ranged in age from 0.9 to 19.8 years (mean 7 years). The duration of follow-up ranged from 1.0 to 8.6 years (mean 2.83 years). Imaging findings, symptoms, and findings on neurological examinations were noted at presentation and for the duration of follow-up.

Results. The mean extent of tonsillar herniation at presentation was 8.35 mm (range 5–22 mm). Seven patients had a syrinx at presentation. The syrinx size did not change in these patients on follow-up imaging studies. No new syrinxes developed in the remaining patients who underwent subsequent imaging. The total number of patients with presenting symptoms was 81. Of those 81 patients, 67 demonstrated symptoms that were not typical of CM-I. Of the 14 patients with symptoms attributed to CM-I, 9 had symptoms that were not severe or frequent enough to warrant surgery, and surgery was recommended in the remaining 5 patients. Chiari malformation Type I was also diagnosed in 43 asymptomatic patients who had imaging studies performed for various reasons. No new neurological deficits were noted in any patient for the duration of follow-up.

Conclusions. The majority of patients with CM-I who are followed up without surgery do not progress clinically or radiologically. Longer follow-up of this cohort will be required to determine if symptoms or new neurological findings develop over the course of many years.

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Onyx embolization for the treatment of brain arteriovenous malformations

Acta Neurochir (2011) 153:869–878. DOI 10.1007/s00701-010-0848-6

Onyx has emerged in recent years for the endovascular treatment of brain arteriovenous malformations (AVMs). However, the role of Onyx embolization is still under discussion. We report our initial experiences in the treatment of brain AVMs with Onyx embolization.

Methods Between January 2004 and December 2007, 86 patients with brain AVMs were embolized with Onyx. Clinical presentation included intracerebral hemorrhage in 32 patients, seizures in 25 patients, headaches in 20 patients, neurologic deficits in 3 patients, and in 6 patients the AVM was an incidental finding. According to the Spetzler–Martin scale, three AVMs were grade I, 13 were grade II, 45 were grade III, 19 were grade IV, and 6 were grade V. Seventy-four AVMs were located in eloquent regions.

Results Initial complete obliteration after final embolization was achieved in 16 patients (18.6%), with an average of 80.5% (range, 30–100%) volume reduction. Partial embolization was followed by surgery in 18 patients, whereas 17 AVMs were cured. In 48 patients treated by embolization and radiosurgery, four patients were lost to follow-up. Three-year follow-up angiography was performed on 30 patients and showed complete obliteration after radiosurgery in 23 patients. The remaining 14 patients are awaiting 3-year postradiosurgery results. Embolization-related permanent morbidity was 3.5%, whereas mortality was 1.2%.

Conclusions Although Onyx allows moderate obliteration rates, combined management, such as adjunctive embolization with microsurgery or radiosurgery, may be effective for selected large AVMs.

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Early endoscope-assisted hematoma evacuation in patients with supratentorial intracerebral hemorrhage: case selection, surgical technique, and long-term results

Neurosurg Focus 30 (4):E9, 2011. DOI: 10.3171/2011.2.FOCUS10313

Currently, the effectiveness of minimally invasive evacuation of intracerebral hemorrhage (ICH) utilizing the endoscopic method is uncertain and the technique is considered investigational.

The authors analyzed their experience with this method in terms of case selection, surgical technique, and long-term results.

Methods. The authors performed a retrospective analysis of the clinical and radiographic data obtained in 68 patients treated with endoscope-assisted ICH evacuation. Rebleeding, morbidity, and mortality were recorded as primary end points. Hematoma evacuation rate was calculated by comparing the pre- and postoperative CT scans. Glasgow Coma Scale scores and scores on the extended Glasgow Outcome Scale (GOSE) were recorded at the 6-month postoperative follow-up. The technical aspect of this report explains details of the procedure, the instruments that are used, the methods for hemostasis, and the role of hemostatic agents in the management of intraoperative hemorrhage. The pertinent literature was reviewed and summarized.

Results. All surgeries were performed within 12 hours of ictus, and 84% of the surgeries were performed within 4 hours. The mortality rate was 5.9%, and surgery-related morbidity occurred in 3 cases (4.4%). The hematoma evacuation rate was 93% overall—96% in the putaminal group, 86% in the thalamic group, and 98% in the subcortical group. The rebleeding rate was 1.5%. The mean operative time was 85 minutes, and the average blood loss was 56 ml. The mean GOSE score was 4.9 at 6-month follow-up. The authors acknowledge the limitations of these preliminary results in a small number of patients.

Conclusions. The data suggest that early endoscope-assisted ICH evacuation is safe and effective in the management of supratentorial ICH. The rebleeding, morbidity, and mortality rates are low compared with rates reported in the literature for the traditional craniotomy method. This study also showed that early and complete evacuation of ICH may lead to improved outcomes in selected patients. However, the safety and efficacy of endoscope-assisted ICH evacuation should be further investigated in a large, prospective, randomized trial.

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Trigeminal schwannomas: experience with 57 cases and a review of the literature

Neurosurg Rev (2011) 34:159–171. DOI 10.1007/s10143-010-0289-y

Trigeminal schwannoma is a mostly benign tumor that can be cured by complete resection. Over the last few decades, several pioneers have developed surgical approaches enabling the total removal of such tumors.

We analyzed 57 patients who underwent radical surgery, including 45 patients who underwent skull base surgery as their initial treatment, for removal of trigeminal schwannomas. Here, we report the surgical management of these cases. Since 1990, all such patients have been treated using three main types of middle fossa skull base approaches, which minimize the exposure of the brain: the anterior transpetrosal approach, subtemporal interdural approach (Dolenc), or a combination of these approaches.

Before 1990, total tumor removal was achieved in only three of eight patients (38%). After 1990, the tumors were totally removed in 43 patients (90%) and were nearly completely removed in an additional three patients (6%). Among the patients who underwent skull base surgery as their initial treatment, a complete resection was achieved in 93% (42/45 patients) of the cases. However, total surgical removal after surgery and Gamma knife surgery was very difficult because of dense adhesions to the brain stem and cranial nerves. No surgery-related mortalities occurred in this series, and the individual KPS scores were more than 90% among the patients who underwent skull base surgery. No recurrences requiring additional surgery have occurred after an average follow-up period of 4.9 years.

Most of the trigeminal schwannomas could be removed totally and safely during a single operation after the introduction of skull base surgery. Therefore, radiosurgery should not be applied as the treatment of first choice for younger patients. A correct anatomical knowledge is critical for minimizing brain exposure and avoiding surgical complications.

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Prevention of Ventriculostomy-Related Infections With Prophylactic Antibiotics and Antibiotic- Coated External Ventricular Drains: A Systematic Review

Neurosurgery 68:996–1005, 2011 DOI: 10.1227/NEU.0b013e3182096d84

Ventriculostomy-related infection (VRI) is a severe complication of external ventricular drain use, occurring in 5% to 23% of patients. Preventive measures for VRI include prolonged prophylactic systemic antibiotics (PSAs) and an antibioticcoated external ventricular drains (ac-EVDs).

OBJECTIVE: We performed a systematic review of all studies evaluating PSAs and ac-EVD for VRI prevention through July 2010.

METHODS: Two reviewers independently assessed eligibility and evaluated study quality based on pre-established criteria. Observational studies and randomized clinical trials (RCTs) that fulfilled inclusion criteria were included in the meta-analysis.

RESULTS: Three RCTs and 7 observational studies met our inclusion criteria and were included in the analysis. The type of antibiotics and VRI definitions varied among these studies. Pooled analysis showed a protective effect of PSAs and ac-EVDs for VRI (risk ratio: 0.32; 95% CI: 0.18-0.56). Results showed moderate heterogeneity (I2 = 53%) explained by the difference in quality among the studies and the inclusion of 1 large positive cohort study. The effect of PSAs and ac-EVDs was unrelated to the type of study (RCT or observational, P for interaction = .55), the route of antibiotic administration (PSAs or ac-EVDs, P = .13), or the quality of the studies (suboptimal vs good/excellent, P = .55).

CONCLUSION: RCTs and observational-derived evidence support the use of PSAs throughout the duration of external ventricular drainage; similarly, the use of ac-EVDs to prevent VRI seems to be beneficial. Available data are heterogeneous and of suboptimal quality. Further research is needed to confirm the findings of this meta-analysis. There are not sufficient data to compare the protective effect of ac-EVDs and PSAs.

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HyperForm balloon remodeling in the endovascular treatment of anterior cerebral, middle cerebral, and anterior communicating artery aneurysms: clinical and angiographic follow-up results in 800 consecutive patients Clinical article

J Neurosurg 114:944–953, 2011. DOI: 10.3171/2010.3.JNS081131

The purpose of this paper was to present the safety, efficacy, and clinical/angiographic follow-up results of HyperForm balloon-assisted endosaccular coil occlusion of distal anterior circulation bifurcation aneurysms.

Methods. Over a 7-year period, the authors treated 864 middle cerebral artery, distal anterior cerebral artery bifurcation, and anterior communicating artery aneurysms by means of coil embolization with HyperForm balloon assistance in 800 patients. In 37 aneurysms, 2 HyperForm balloons were used simultaneously for remodeling.

Results. The overall mortality rate was 7.1%, including 1.4% procedural mortality. Various neurological deficits were present at discharge in 8.9% of the patients, and 4.4% had permanent disabling morbidity 6 months posttreatment (modified Rankin Scale score ≥ 2). Thromboembolic complications developed during the treatment of 15 aneurysms (1.7%) causing morbidity or mortality in 10 cases (1.3%). There were 14 intraoperative perforations (1.6%). In all 14 cases, the HyperForm balloon saved patients from severe bleeding. The perforation led to morbidity or mortality in 3 cases (0.4%); there were no negative consequences in 11. There were 726 patients with 757 aneurysms (87.6%) available for follow-up. Control angiograms were obtained at 6 months in 386 patients, at 1 year in 267, and at 2 years in 104, revealing an 82% complete obliteration rate according to the most recent follow-up angiograms.

Conclusions. The satisfactory results obtained in this experience demonstrate that HyperForm balloon remodeling provides strong benefits for the endovascular management of middle cerebral, anterior cerebral, and anterior communicating artery aneurysms without increasing the risk of treatment. Not only does this technique allow for the safe treatment of these aneurysms, but it also expands the indications of endovascular treatment to include aneurysms that otherwise cannot be treated with simple coil embolization.

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The role of DTI in early detection of cervical spondylotic myelopathy: a preliminary study with 3-T MRI

Neuroradiology. DOI 10.1007/s00234-011-0844-4

The radiological diagnosis of cervical spondylotic myelopathy (CSM) has to be made as soon as possible, since surgery performed in earlier stages during the course of CSM was reported to be more successful when compared with later stages. We hypothesized that diffusion tensor imaging (DTI) may detect CSM in earlier stages, before the appearance of signal increase in T2- weighted sequences.

Methods A total of 16 patients with neurological signs and symptoms of CSM but without hyperintensity in spinal cord on T2-weighted sequences enrolled in the study. The magnetic resonance (MR) examinations were performed on a 3-T MR imaging system. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps were generated on axial plane. The ADC and FA measurements in each individual were made at the level of most severe cervical canal stenosis and at a nonstenotic level. Student’s t test was used to compare FA and ADC values of the spinal cord in stenotic and nonstenotic segments. We also investigated if there was a correlation between DTI parametrics and duration of clinical symptoms by using Pearson correlation analysis.

Results All patients showed changes in DTI parametrics at stenotic segments. While FA values of the spinal cord at the stenotic level showed a statistically significant reduction, there was a statistically significant increase in the measured ADC values (p<0.001). There was no statistical correlation between the duration of symptoms and DTI parametrics.

Conclusion Our preliminary findings indicate that DTI may show abnormalities in the spinal cord before the development of T2 hyperintensity on conventional sequences in patients with CSM.

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Intraventricular craniopharyngioma: morphological analysis and outcome evaluation of 17 cases

Acta Neurochir (2011) 153:773–784. DOI 10.1007/s00701-010-0938-5

There is still some confusion with regard to the tumor–third ventricle floor (3rd VF) relationship of craniopharyngiomas located exclusively within the third ventricle. This study aims to provide some evidence to clarify the growth pattern of intraventricular craniopharyngiomas (IVC), and to summarize the surgical strategy and outcome.

Methods Seventeen cases of IVC were reviewed retrospectively in relation to preoperative imaging, clinical presentation, intraoperative findings, tumor pathology, and surgical outcome. The tumor–3rd VF relationship and the tumor’s stratification were analyzed based on intraoperative inspection and histology.

Findings: Variable adherence patterns of IVC to the 3rd VF were found, which were classified as (a) purely IVC with pedicle attachment to 3rd VF (two cases), (b) intra-3rd VF tumors with wide-based attachment but a dissectible tumor boundary (seven cases), and (c) intra-3rd VF tumors with an undissectible wide, tight attachment (eight cases). Histological analysis revealed that both of the two cases with growth pattern “a” intruded into the third ventricular cavity without a covering layer of neural tissue (which only exists in the squamous-papillary subtype). Tumors with growth pattern “b” and “c,” in contrast, were noted to have a thin layer of neural tissue. This occurred in both subtypes (11 adamantinomatous, 4 papillary). Total removal was accomplished in all tumors demonstrating growth pattern “a” and “b.” There was also better preservation of the 3rd VF and consequently a better outcome. On the other hand, total removal was only achieved in 50% of tumors showing growth pattern “c” including one mortality. No recurrence has been encountered in patients whose tumors were totally removed.

Conclusion Variable adherence patterns and tumor subtypes were observed in IVCs, which were correlated to the tumor pathology, resectability, and subsequent prognosis.

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