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Discriminating radiation necrosis from tumor progression in gliomas: a systematic review what is the best imaging modality?

Radiation necrosis

J Neurooncol (2013) 112:141–152

Differentiating post radiation necrosis from progression of glioma and pseudoprogression poses a diagnostic conundrum for many clinicians. As radiation therapy and temozolomide chemotherapy have become the mainstay of treatment for higher-grade gliomas, radiation necrosis and post treatment changes such as pseudoprogression have become a more relevant clinical problem for neurosurgeons and neurooncologists. Due to their radiological similarity to tumor progression, accurate recognition of these findings remains paramount given their vastly different treatment regimens and prognoses. However, no consensus has been reached on the optimal technique to discriminate between these two lesions.

In order to clarify the types of imaging modalities for recurrent enhancing lesions, we conducted a systematic review of case reports, case series, and prospective studies to increase our current understanding of the imaging options for these common lesions and their efficacy. In particular, we were interested in distinguishing radiation necrosis from true tumor progression. A PubMed search was performed to include all relevant studies where the imaging was used to differentiate between radiation necrosis and recurrent gliomas with post-radiation enhancing lesions.

After screening for certain parameters in our study, seventeen articles with 435 patients were included in our analysis including 10 retrospective and 7 prospective studies. The average time from the end of radiation therapy to the onset of a recurrent enhancing lesion was 13.2 months. The most sensitive and specific imaging modality was SPECT with a sensitivity of 87.6 % and specificity of 97.8 %.

Based on our review, we conclude that certain imaging modalities may be preferred over other less sensitive/specific techniques. Overall, tests such as SPECT may be preferable in differentiating TP (tumor progression) from RN (radiation necrosis) due to its high specificity, while nonspecific imaging such as conventional MRI is not ideal.

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Noninvasive Language Mapping in Patients With Epilepsy or Brain Tumors

Noninvasive_Language_Mapping_in_Patients_With

Neurosurgery 72:555–565, 2013

Functional magnetic resonance imaging (fMRI) has become part of routine brain mapping in patients with epilepsy or tumor undergoing resective surgery. However, robust localization of crucial functional areas is required.

OBJECTIVE: To establish a simple, short fMRI task that reliably localizes crucial language areas in individual patients who undergo respective surgery.

METHODS: fMRI was measured during an 8-minute auditory semantic decision task in 28 healthy controls and 35 consecutive patients who had focal epilepsy or a brain tumor. Nineteen underwent resective surgery. Group and individual analyses were performed. Results in patients were compared with postsurgical language outcome and electrocortical stimulation when available.

RESULTS: fMRI activations concordant with the anterior and posterior language areas were found in 96% and 89% of the controls, respectively. The anterior and posterior language areas were both activated in 93% of the patients. These results were concordant with electrocortical stimulation results in 5 patients. Transient postsurgical language deficits were found in 2 patients in whom surgery was performed in the vicinity of the fMRI activations or who had postsurgical complications implicating areas of fMRI activations.

CONCLUSION: The proposed fast fMRI language protocol reliably localized the most relevant language areas in individual subjects. It appears to be a valuable complementary tool for surgical planning of epileptogenic foci and of brain tumors.

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Rigid occipitocervical fixation: indications, outcomes, and complications in the modern era

Rigid occipitocervical fixation- indications, outcomes, and complications in the modern era

J Neurosurg Spine 18:333–339, 2013

Over the past 40 years, various methods and instrumentation types have been developed for occipitocervical fixation (OCF) in the management of occipitocervical instability. This study reports indications, outcomes, and complications with rigid OCF using screw-rod and screw-plate instrumentation, which has comparatively less long-term data.

Methods. A prospectively maintained database identified 100 consecutive patients who underwent rigid OCF in a single unit over a period of 13 years. Patient demographics, clinical indications, pre- and postoperative radiographic findings, neck disability indices (NDIs), myelopathy disability indices (MDIs), visual analog scale (VAS) scores, and Ranawat scores were recorded. Complications including instrumentation failure were also documented.

Results. Underlying etiologies included rheumatoid arthritis (RA; 41%), tumor (16%), trauma (15%), congenital etiologies (14%), metabolic (6%) and inflammatory (6%) conditions, and infection (2%). The pre- and postoperative MDI and VAS scores for neck pain showed significant improvements in the RA group (MDI 64.5% vs 42.5%, p = 0.02; mean VAS 7.5 of 10 vs 3.7 of 10, p < 0.001). Improvements in MDI and NDI outcome measures were also seen in the trauma and tumor categories. Overall, there were 4 cases of instrumentation failure; all included broken rods in the stress riser region of occipitocervical rod curvature, and 1 patient also had occipital plate screw pullout. Other complications included 5 wound infections requiring wound washout, 1 vertebral artery injury (no clinical sequelae), and 1 perioperative death due to myocardial infarction.

Conclusions. Rigid OCF is a safe and effective method of managing occipitocervical instability due to a variety of causes. Outcome measures are favorable, and patients with chronically debilitating diseases such as RA may benefit in terms of improvements in neurological deficit and neck pain. The complication profile is comparable to that reported in other series of OCF in the literature, as well as to the previously used semirigid type of rod/sublaminar wire fixation.

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Subarachnoid Hemorrhage With Negative Initial Catheter Angiography

Subarachnoid_Hemorrhage_With_Negative_Initial

Neurosurgery 72:646–652, 2013

Subarachnoid hemorrhage (SAH) is found to have no vascular origin by initial catheter angiography in approximately 15% of cases. The most appropriate course for the type and frequency of additional diagnostic workup remains controversial.

OBJECTIVE: To retrospectively assess the diagnostic yield of short-term and long-term repeat catheter angiography in the era of advanced imaging.

METHODS: Between 2003 and 2011, 254 consecutive patients diagnosed with SAH had negative initial angiography. SAH was perimesencephalic (PM) in 46.5% and nonperimesencephalic (NPM) in 53.5%. Angiography was repeated at 1-week (short-term) and 6-week (long-term) intervals from the initial negative angiogram.

RESULTS: Ten of 254 patients had a vascular source of hemorrhage on short-term follow-up angiography with a diagnostic yield of 3.9%. One hundred seventy-four patients with negative findings on the first 2 angiograms received a third angiogram, and 7 of these patients were found to have a vascular abnormality. The estimated yield of this third angiogram was 4.0%. The overall diagnostic yield of repeat angiography was 0% in the PM group and 12.5% in the NPM group. The diagnostic yield of shortterm and long-term follow-up angiography in patients with NPM SAH was 7.3% and 7.8%, respectively. NPM patients were more likely to experience vasospasm and hydrocephalus requiring external ventricular drainage or cerebrospinal fluid diversion than PM patients.

CONCLUSION: Our results support a protocol of short-term and long-term angiographic follow-up in patients with NPM SAH and negative initial angiography. Aggressive protocols of follow-up angiography may not be necessary in patients with PM SAH.

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Navigated transcranial magnetic stimulation for mapping the motor cortex in patients with rolandic brain tumors

Navigated transcranial

Neurosurg Focus 34 (4):E3, 2013

Navigated transcranial magnetic stimulation (nTMS) is a novel technology in the field of neurosurgery for noninvasive delineation of cortical functional topography. This study addresses the spatial accuracy and clinical usefulness of nTMS in brain tumor surgery in or near the motor cortex based on a systematic review of observational studies.

Methods. A systematic search retrieved 11 reports published up to October 2012 in which adult patients were examined with nTMS prior to surgery. Quality criteria consisted of documentation of the influence of nTMS brain mapping on clinical decision making in a standardized prospective manner and/or performance of intraoperative direct electrical stimulation (DES) and comparison with nTMS results. Cross-observational assessment of nTMS accuracy was established by calculating a weighted mean distance between nTMS and DES.

Results. All studies reviewed in this article concluded that nTMS correlated well with the “gold standard” of DES. The mean distance between motor cortex identified on nTMS and DES by using the mean distance in 81 patients described in 6 quantitatively evaluated studies was 6.18 mm. The nTMS results changed the surgical strategy based on anatomical imaging alone in 25.3% of all patients, based on the data obtained in 87 patients in 2 studies.

Conclusions. The nTMS technique spatially correlates well with the gold standard of DES. Its functional information benefits surgical decision making and changes the treatment strategy in one-fourth of cases.

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Minimal access to deep intracranial lesions using a serial dilatation technique

Minimal access to deep intracranial lesions

Neurosurg Rev (2013) 36:321–330

Surgical access to deep intracranial lesions causing the least amount of iatrogenic trauma to the surrounding brain tissue remains a challenging task. In this article, we evaluate the use of a set of sequential tubes that dilate and provide retraction of the overlying brain tissue acting as a surgical corridor for deep-seated brain lesions resection. In addition, we conducted a comprehensive review of the literature of previously described techniques using variable brain tubular retractor systems. We discuss the adaptation of a system designed for spinal use to intracranial pathologies and evaluate the outcomes for the patients involved in the study. Moreover, the advantages and limitations of the described technique were presented.

Between August 2005 and 2011, a total of 30 patients with deep brain lesions were operated on using an incremental increase of tubing size for brain retraction guided by a frameless navigation device. Of these, seven cases were intraventricular, and 23 were intraparenchymal. Gross total resection was achieved in 70 % of cases, and the remaining had planned subtotal resections due to involvement of an eloquent area.

In conclusion, the technique of serial dilatation of the brain tissue can be used in conjunction with a microscope or endoscope to provide satisfactory access to deep intracranial pathologies. It appears to minimize the associated retraction injury to the surrounding tissue by gradually dilating the white fiber tracts. This operative approach may be considered as an effective and safe alternative for brain tumor resections in selected cases, especially deep-seated lesions.

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Accuracy and complications associated with the freehand C-1 lateral mass screw fixation technique

Accuracy and complications associated with the freehand C-1 lateral mass screw fixation technique

J Neurosurg Spine 18:372–377, 2013

The aims of this study were to evaluate a large series of posterior C-1 lateral mass screws (LMSs) to determine accuracy based on CT scanning findings and to assess the perioperative complication rate related to errant screw placement.

Methods. Accuracy of screw placement was evaluated using postoperative CT scans obtained in 196 patients with atlantoaxial instability. Radiographic analysis included measurement of preoperative and postoperative CT scans to evaluate relevant anatomy and classify accuracy of instrumentation placement. Screws were graded using the following definitions: Type I, screw threads completely within the bone (ideal); Type II, less than half the diameter of the screw violates the surrounding cortex (safe); and Type III, clear violation of transverse foramen or spinal canal (unacceptable).

Results. A total of 390 C-1 LMSs were placed, but 32 screws (8.2%) were excluded from accuracy measurements because of a lack of postoperative CT scans; patients in these cases were still included in the assessment of potential clinical complications based on clinical records. Of the 358 evaluable screws with postoperative CT scanning, 85.5% of screws (Type I) were rated as being in the ideal position, 11.7% of screws (Type II) were rated as occupying a safe position, and 10 screws (2.8%) were unacceptable (Type III). Overall, 97.2% of screws were rated Type I or II. Of the 10 screws that were unacceptable on postoperative CT scans, there were no known associated neurological or vertebral artery (VA) injuries. Seven unacceptable screws erred medially into the spinal canal, and 2 patients underwent revision surgery for medial screws. In 2 patients, unilateral C-1 LMSs penetrated the C-1 anterior cortex by approximately 4 mm. Neither patient with anterior C-1 penetration had evidence of internal carotid artery or hypoglossal nerve injury. Computed tomography scanning showed partial entry of C-1 LMSs into the VA foramen of C-1 in 10 cases; no occlusion, associated aneurysm, or fistula of the VA was found. Two patients complained of postoperative occipital neuralgia. This was transient in one patient and resolved by 2 months after surgery. The second patient developed persistent neuralgia, which remained 2 years after surgery, necessitating referral to the pain service.

Conclusions. The technique for freehand C-1 LMS fixation appears to be safe and effective without intraoperative fluoroscopy guidance. Preoperative planning and determination of the ideal screw insertion point, the ideal trajectory, and screw length are the most important considerations. In addition, fewer malpositioned screws were inserted as the study progressed, suggesting a learning curve to the technique.

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Brainstem gangliogliomas: a retrospective series

Brainstem gangliogliomas- a retrospective series

J Neurosurg 118:884–888, 2013

The authors retrospectively analyzed data on brainstem gangliogliomas treated in their department and reviewed the pertinent literature to foster understanding of the preoperative characteristics, management, and clinical outcomes of this disease.

Methods. In 2006, the authors established a database of treated lesions of the posterior fossa. The epidemiology findings, clinical presentations, radiological investigations, pathological diagnoses, management, and prognosis for brainstem gangliogliomas were retrospectively analyzed.

Results. Between 2006 and 2012, 7 patients suffering from brainstem ganglioglioma were treated at the West China Hospital of Sichuan University. The mean age of the patients, mean duration of symptoms prior to diagnosis, and mean duration of follow-up were 28.6 years, 19.4 months, and 38.1 months, respectively. The main presentations were progressive cranial nerve deficits and cerebellar signs. Subtotal resection was achieved in 2 patients, and partial resection in 5. All tumors were pathologically diagnosed as WHO Grade I or II ganglioglioma. Radiotherapy and adjuvant chemotherapy were not administered. After 21–69 months of follow-up, patient symptoms were resolved or stable without aggravation, and MRI showed that the size of residual lesions was unchanged without progression or recurrence.

Conclusions. The diagnosis of brainstem ganglioglioma is of great importance given its favorable prognosis. The authors recommend the maximal safe resection followed by close observation without adjuvant therapy as the optimal treatment for this disease.

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Stereoelectroencephalography: Surgical Methodology, Safety, and Stereotactic Application Accuracy in 500 Procedures

Stereoelectroencephalography___Surgical

Neurosurgery 72:353–366, 2013

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

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

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

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

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

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Use of diffusion tensor imaging in glioma resection

DTI.glioma

Neurosurg Focus 34 (4):E1, 2013 

Diffusion tensor imaging (DTI) is increasingly used in the resection of both high- and low-grade gliomas. Whereas conventional MRI techniques provide only anatomical information, DTI offers data on CNS connectivity by enabling visualization of important white matter tracts in the brain

Importantly, DTI allows neurosurgeons to better guide their surgical approach and resection. Here, the authors review basic scientific principles of DTI, include a primer on the technology and image acquisition, and outline the modality’s evolution as a frequently used tool for glioma resection.

Current literature supporting its use is summarized, highlighting important clinical studies on the application of DTI in preoperative planning for glioma resection, preoperative diagnosis, and postoperative outcomes.

The authors conclude with a review of future directions for this technology.

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Three-dimensional angioarchitecture of spinal dural arteriovenous fistulas, with special reference to the intradural retrograde venous drainage system

Three-dimensional angioarchitecture of spinal dural arteriovenous fistulas, with special reference to the intradural retrograde venous drainage system

J Neurosurg Spine 18:398–408, 2013

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

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

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

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

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A systematic review of functional magnetic resonance imaging and diffusion tensor imaging modalities used in presurgical planning of brain tumour resection

fMRI and DTI

Neurosurg Rev (2013) 36:205–214

Historically, brain tumour resection has relied upon standardised anatomical atlases and classical mapping techniques for successful resection. While these have provided adequate results in the past, the emergence of new technologies has heralded a wave of less invasive, patient-specific techniques for the mapping of brain function.

Functional magnetic resonance imaging (fMRI) and, more recently, diffusion tensor imaging (DTI) are two such techniques. While fMRI is able to highlight localisation of function within the cortex, DTI represents the only technique able to elucidate white matter structures in vivo. Used in conjunction, both of these techniques provide important presurgical information for thorough preoperative planning, as well as intraoperatively via integration into frameless stereotactic neuronavigational systems.

Together, these techniques show great promise for improved neurosurgical outcomes. While further research is required for more widespread clinical validity and acceptance, results from the literature provide a clear road map for future research and development to cement these techniques into the clinical setup of neurosurgical departments globally.

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Spontaneous speech of patients with gliomas in eloquent areas before and early after surgery

Aphasia induced by gliomas

Acta Neurochir Volume 155, Issue 4, April 2013, 685-692

Glioma patients often complain about problems in daily conversation. A detailed spontaneous speech analysis could provide more insight in these communicative problems; no previous studies are reported.
Objective
To select sensitive parameters in spontaneous speech pre- and post-operatively in patients with gliomas in eloquent areas.
Methods
We included 27 patients and 21 healthy controls. In addition to a naming and category fluency test, spontaneous speech was collected 1 month pre-operatively and 3 months post-operatively, and analysed with the variables: Self-corrections, Repetitions, Lexical Diversity, Incomplete Sentences and Mean Length of Utterance (MLUw). A correlation analysis was performed between the linguistic variables and tumour characteristics (grade, localisation and volume), treatment related factors, and between the linguistic variables and the language tasks.
Results
Pre-operatively, patients produced more Incomplete Sentences than the controls (p < 0.001). Post-operatively, patients’ utterance length (MLUw) (p < 0.05) was also deviant. The quality of the spontaneous speech was influenced by tumour grade and localisation. There was no influence of tumour volume or treatment-related factors. Pre- and post-operatively, patients’ performance on the naming and the fluency task deviated from normal (p < 0.001). The majority of the linguistic variables did not correlate with the language tasks, pointing to a measurement of distinct linguistic aspects.
Conclusion
Pre- and post-operatively there was a disorder in naming, category fluency and spontaneous speech, partly influenced by tumour characteristics. A spontaneous speech analysis appeared to be a valuable addition to standardised language tasks. Both measurements are important tools to obtain a complete linguistic profile.
Keywords

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Cavernous Malformation of Brainstem, Thalamus, and Basal Ganglia: A Series of 176 Patients

Cavernous_Malformation_of_Brainstem,_Thalamus,_and

Neurosurgery 72:573–589, 2013

Cavernous malformations (CMs) in deep locations account for 9% to 35% of brain malformations and are surgically challenging.

OBJECTIVE: To study the clinical features and outcomes following surgery for deep CMs and the complication of hypertrophic olivary degeneration (HOD).

METHODS: Clinical records, radiological findings, operative details, and complications of 176 patients with deep CMs were reviewed retrospectively.

RESULTS: Of 176 patients with 179 CMs, 136 CMs were in the brainstem, 27 in the basal ganglia, and 16 in the thalamus. Cranial nerve deficits (51.1%), hemiparesis (40.9%), numbness (34.7%), and cerebellar symptoms (38.6%) presented most commonly. Hemorrhage presented in 172 patients (70 single, 102 multiple). The annual retrospective hemorrhage rate was 5.1% (assuming CMs are congenital with uniform hemorrhage risk throughout life); the rebleed rate was 31.5%/patient per year. Surgical approach depended on the proximity of the CM to the pial or ependymal surface. Postoperatively, 121 patients (68.8%) had no new neurological deficits. Follow-up occurred in 170 patients. Delayed postoperative HOD developed in 9/134 (6.7%) patients with brainstem CMs. HOD occurred predominantly following surgery for pontine CMs (9/10 patients). Three patients with HOD had palatal myoclonus, nystagmus, and oscillopsia, whereas 1 patient each had limb tremor and hemiballismus. At follow-up, 105 patients (61.8%) improved, 44 (25.9%) were unchanged, and 19 (11.2%) worsened neurologically. Good preoperative modified Rankin Score (98.2% vs 54.5%, P = .001) and single hemorrhage (89% vs 77.3%, P , .05) were predictive of good longterm outcome.

CONCLUSION: Symptomatic deep CMs can be resected with acceptable morbidity and outcomes. Good preoperative modified Rankin Score and single hemorrhage are predictors of good long-term outcome.

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Separation surgery and postoperative SRS for spinal metastases

Local disease control for spinal metastases following “separation surgery” and adjuvant hypofractionated or high-dose single-fraction stereotactic radiosurgery

J Neurosurg Spine 18:207–214, 2013

Decompression surgery followed by adjuvant radiotherapy is an effective therapy for preservation or recovery of neurological function and achieving durable local disease control in patients suffering from metastatic epidural spinal cord compression (ESCC). The authors examine the outcomes of postoperative image-guided intensity-modulated radiation therapy delivered as single-fraction or hypofractionated stereotactic radiosurgery (SRS) for achieving long-term local tumor control.

Methods. A retrospective chart review identified 186 patients with ESCC from spinal metastases who were treated with surgical decompression, instrumentation, and postoperative radiation delivered as either single-fraction SRS (24 Gy) in 40 patients (21.5%), high-dose hypofractionated SRS (24–30 Gy in 3 fractions) in 37 patients (19.9%), or low-dose hypofractionated SRS (18–36 Gy in 5 or 6 fractions) in 109 patients (58.6%). The relationships between postoperative adjuvant SRS dosing and fractionation, patient characteristics, tumor histology–specific radiosensitivity, grade of ESCC, extent of surgical decompression, response to preoperative radiotherapy, and local tumor control were evaluated by competing risks analysis.

Results. The total cumulative incidence of local progression was 16.4% 1 year after SRS. Multivariate Gray competing risks analysis revealed a significant improvement in local control with high-dose hypofractionated SRS (4.1% cumulative incidence of local progression at 1 year, HR 0.12, p = 0.04) as compared with low-dose hypofractionated SRS (22.6% local progression at 1 year, HR 1). Although univariate analysis demonstrated a trend toward greater risk of local progression for patients in whom preoperative conventional external beam radiation therapy failed (22.2% local progression at 1 year, HR 1.96, p = 0.07) compared with patients who did not receive any preoperative radiotherapy (11.2% local progression at 1 year, HR 1), this association was not confirmed with multivariate analysis. No other variable significantly correlated with progression-free survival, including radiation sensitivity of tumor histology, grade of ESCC, extent of surgical decompression, or patient sex.

Conclusions. Postoperative adjuvant SRS following epidural spinal cord decompression and instrumentation is a safe and effective strategy for establishing durable local tumor control regardless of tumor histology–specific radiosensitivity. Patients who received high-dose hypofractionated SRS demonstrated 1-year local progression rates of less than 5% (95% CI 0%–12.2%), which were superior to the results of low-dose hypofractionated SRS. The local progression rate after singlefraction SRS was less than 10% (95% CI 0%–19.0%).

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Use of the NeuroBalloon catheter for endoscopic third ventriculostomy

endoscopic third ventriculostomy

J Neurosurg Pediatrics 11:302–306, 2013

Endoscopic third ventriculostomy (ETV) has become the procedure of choice for treatment of obstructive hydrocephalus.

While patient selection is the most critical factor in determining the success of an ETV procedure, the technical challenge lies in the proper site of fenestration and the successful creation of a patent stoma.

Positioning of a single balloon catheter at the level or below the floor of the third ventricle to achieve an optimal ventriculostomy can at times be challenging.

Here, the authors describe the use of a double-barrel balloon catheter (NeuroBalloon catheter), which facilitates positioning across, as well as dilation of, the floor of the third ventricle.

The surgical technique and nuances of using the NeuroBalloon catheter and the experience in more than 1000 cases are described. The occurrence of vascular injury was less than 0.1%, and the risk of balloon rupture was less than 2%.

The authors found that the placement and deployment of this balloon catheter facilitate the creation of an adequate ventriculostomy in a few simple steps.

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Flat-Panel Fluoroscopy O-arm–Guided Percutaneous Radiofrequency Cordotomy: A New Technique for the Treatment of Unilateral Cancer Pain

O-arm cordotomy

Neurosurgery 72[ONS Suppl 1]:ons27–ons34, 2013

Percutaneous radiofrequency cordotomy (PRFC) involves controlled ablation of the anterolateral quadrant of the spinal cord, thereby relieving pain. Evolving from a morbid open surgery, the procedure has been modernized through the application of physiological target confirmation, well-regulated thermal ablation, and improved intraoperative imaging.

OBJECTIVE: To evaluate the utility in PRFC of a new high-resolution, portable flatpanel fluoroscopic imaging technology, the O-arm Imaging System. The O-arm allows traditional 2-dimensional fluoroscopy in addition to axial and 3-dimensional reconstructed computed tomography imaging.

METHODS: PRFC was performed using the O-arm Imaging System in 6 patients with unilateral cancer pain.

RESULTS: Patients experienced 90% to 100% initial pain relief, with 50% to 100% sustained pain relief at the time of death at 2 to 12 months. There were no complications.

CONCLUSION: Portable flat-panel fluoroscopy allows high-resolution, readily updated computed tomography and fluoroscopic image guidance during PRFC. Use of this new technology may assist neurosurgeons in providing an important analgesic intervention at centers possessing the imaging technology.

KEY WORDS:

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Endoscopic endonasal skull base surgery in the pediatric population

Epeds12160-1

J Neurosurg Pediatrics 11:227–241, 2013

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

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

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

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

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Definition of a Stereotactic 3-Dimensional Magnetic Resonance Imaging Template of the Human Insula

3D MRI template of the insula

Neurosurgery 72[ONS Suppl 1]:ons35–ons46, 2013

This study proposes a 3-dimensional (3-D) template of the insula in the bicommissural reference system with posterior commissure (PC) as the center of coordinates.

OBJECTIVE: Using the bicommissural anterior commissure (AC)–PC reference system, this study aimed to define a template and design a method for the 3-D reconstruction of the human insula that may be used at an individual level during stereotactic surgery.

METHODS: Magnetic resonance imaging (MRI)–based morphometric analysis was performed on 100 cerebral cortices with normal insulae based on a 3-step procedure: Step 1: AC-PC reference system–based reconstruction of the insula from the 1-mm thick 3-D T1-weighted MRI slices. Step 2: Digitalization and superposition of the data obtained in the 3 spatial planes. Step 3: Representation of pixels as colors on a scale corresponding to the probability of localization of each insular anatomic component.

RESULTS: The morphometric analysis of the insula confirmed our previously reported findings of a more complex shape delimited by 4 peri-insular sulci. A very significant correlation between the coordinates of the main insular structures and the length of AC-PC was demonstrated. This close correlation allowed us to develop a method that allows the 3-D reconstruction of the insula from MRI slices and only requires the localization of AC and PC. This process defines an area deemed to contain insula with 100% probability.

CONCLUSION: This 3-D reconstruction of the insula should be useful to improve its localization and other cortical areas and allow the differentiation of insular cortex from opercular cortex. KEY WORDS:

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Pelvic Schwannoma: Robotic Laparoscopic Resection

Pelvic Schwannoma- Robotic Laparoscopic Resection

Neurosurgery 72[ONS Suppl 1]:ons2–ons5, 2013

Schwannoma is a rare benign tumor of peripheral nerves arising from Schwann cells of the ubiquitous nerve sheath.

OBJECTIVE: To describe the operative steps and technical aspects of robotic laparoscopic resection of pelvic schwannoma.

METHODS: We describe 2 patients with pelvic schwannoma: a 34-year-old woman with schwannoma of the right lumbosacral trunk and a 58-year-old woman with schwannoma of a left S1 nerve. Pain was the main symptom in both patients. The diagnosis was confirmed by magnetic resonance imaging and nerve biopsies. Both patients were operated on by robotic laparoscopy.

RESULTS: Lesions were totally enucleated after incising the epineurium. After dissection of the schwannoma, the vascular pedicle and nerve fascicles involved were identified, coagulated, and then sectioned. The remaining fascicles of the nerve were preserved. The postoperative course was uneventful in both patients. With follow-up of 9 and 13 months, both patients obtained complete pain relief with no neurological sequelae. CONCLUSION: Robotic laparoscopic resection of pelvic nerve tumors such as schwannomas is technically feasible.

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