Author: cba

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Percutaneous endoscopic treatment of foraminal and extraforaminal disc herniation at the L5-S1 level

Acta Neurochir (2012) 154:1789–1795

Microsurgery of foraminal and extraforaminal disc herniation at the L5-S1 level remains a challenge because of the limited access by a high iliac crest, the sacral ala, large transverse processes of L5 and hidden disc fragments lateral to the zygapophyseal joint.

Our aim was to present the outcome of percutaneous endoscopic lumbar discectomy (PELD) of these lateral and far lateral disc herniations at the L5-S1 level using the newly described foraminal retreat technique in a group of patients with similar preoperative diagnostic studies.

Methods A total of 22 patients, 13 males and 9 females, with foraminal and extraforaminal lumbar disc herniation at the L5-S1 level were treated by applying the PELD between September 2004 and April 2010. The clinical findings and MRI were the main diagnostic methods. Preoperative evaluation was performed with clinical examinations, the Visual Analog Pain Scale (VAS) and Oswestry Low Back Disability Index (ODI).

Findings According to the Macnab criteria, overall excellent or good outcomes were obtained in 18 patients (81.8 %), fair outcomes in 3 patients (13.6 %) and a poor outcome in 1 patient (4.5 %) at the last follow-up. The mean ODI was 67.3±19.4 preoperatively and 26.7±23.4 postoperatively. Preoperative VAS was 88.6±7.6 and 28.6±22.8 at 2 days, 40.5±22.8 at 3 weeks, 34.3±25.1 at 6-months and 32 at the last follow-up. At follow-up, two patients (9.1 %) had recurrent disc herniations that were corrected with open surgery. At the time of surgery, 16 patients held jobs. Fifteen (15) patients (93.8 %) returned to their original jobs postoperatively; one patient could not return to his original job postoperatively because of a comorbidity.

Conclusions Percutaneous endoscopic discectomy using the foraminal retreat technique is an effective treatment method for patients with foraminal and extraforaminal disc herniations at the L5-S1 level on appropriately selected patients.

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Role of lumbar interspinous distraction on the neural elements

Neurosurg Rev (2012) 35:477–484

The interspinous distraction devices are used to treat variable pathologies ranging from facet syndrome, diskogenic low back pain, degenerative spinal stenosis, diskopathy, spondylolisthesis, and instability. The insertion of a posterior element with an interspinous device (ISD) is commonly judged responsive to a relative kyphosis of a lumbar segment with a moderate but persistent increase of the spinal canal and of the foraminal width and area, and without influence on low-grade spondylolisthesis. The consequence is the need of shared specific biomechanical concepts to give for each degenerative problem the right indication through a critical analysis of all available experimental and clinical biomechanical data. We reviewed systematically the available clinical and experimental data about kyphosis, enlargement of the spinal canal, distraction of the interspinous distance, increase of the neural foramina, ligamentous structures, load of the posterior annulus, intradiskal pressure, strength of the spinous processes, degeneration of the adjacent segment, complications, and cost-effectiveness of the ISD. The existing literature does not provide actual scientific evidence over the superiority of the ISD strategy, but most of the experimental and clinical data show a challenging potential. These considerations are applicable with different types of ISD with only few differences between the different categories. Despite—or because of—the low invasiveness of the surgical implantation of the ISD, this technique promises to play a major role in the future degenerative lumbar microsurgery. The main indications for ISD remain lumbar spinal stenoses and painful facet arthroses. A clear documented contraindication is the presence of an anterolisthesis. Nevertheless, the existing literature does not provide evidence of superiority of outcome and cost-effectiveness of the ISD strategy over laminectomy or other surgical procedures. At this time, the devices should be used in clinical randomized independent trials in order to obtain more information concerning the most advantageous optimal indication or, in selected cases, to treat tailored indications.

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Removal of an ICH through an eyebrow incision

J Neurosurg 117:767–773, 2012

Surgical evacuation of spontaneous intracerebral hemorrhage (sICH) remains a subject of controversy. Minimally invasive techniques for hematoma evacuation have shown a trend toward improved outcomes. The aim of the present study is to describe a minimally invasive alternative for the evacuation of sICH and evaluate its feasibility.
Methods
The authors reviewed records of all patients who underwent endoscopic evacuation of an sICH at the UCLA Medical Center between March 2002 and March 2011. All patients in whom the described technique was used for evacuation of an sICH were included in this series. In this approach an incision is made at the superior margin of the eyebrow, and a bur hole is made in the supraorbital bone lateral to the frontal sinus. Using stereotactic guidance, the surgeon advanced the endoscopic sheath along the long axis of the hematoma and fixed it in place at two specific depths where suction was then applied until 75%–85% of the preoperatively determined hematoma volume was removed. An endoscope’s camera, then introduced through the sheath, was used to assist in hemostasis. Preoperative and postoperative hematoma volumes and reduction in midline shift were calculated and recorded. Admission Glasgow Coma Scale and modified Rankin Scale (mRS) scores were compared with postoperative scores.
Results
Six patients underwent evacuation of an sICH using the eyebrow/bur hole technique. The mean preoperative hematoma volume was 68.9 ml (range 30.2–153.9 ml), whereas the mean postoperative residual hematoma volume was 11.9 ml (range 5.1–24.1 ml) (p = 0.02). The mean percentage of hematoma evacuated was 79.2% (range 49%–92.7%). The mean reduction in midline shift was 57.8% (p < 0.01). The Glasgow Coma Scale score improved in each patient between admission and discharge examination. In 5 of the 6 patients the mRS score improved from admission exam to last follow-up. None of the patients experienced rebleeding.
Conclusions
This minimally invasive technique is a feasible alternative to other means of evacuating sICHs. It is intended for anterior basal ganglia hematomas, which usually have an elongated, ovoid shape. The approach allows for an optimal trajectory to the long axis of the hematoma, making it possible to evacuate the vast majority of the clot with only one pass of the endoscopic sheath, theoretically minimizing the amount of damage to normal brain.

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Near-infrared indocyanine green videoangiography (ICGVA) and intraoperative computed tomography (iCT): are they complementary or competitive imaging techniques in aneurysm surgery?

Acta Neurochir (2012) 154:1861–1868

In this pilot study we compared advantages and drawbacks of near-infrared indocyanine green videoangiography (ICGVA) and intraoperative computed tomography (iCT) to investigate if these are complementary or competitive methods to acquire immediate information about blood vessels and potential critical impairment of brain perfusion during vascular neurosurgery.
Methods
A small subset of patients (n = 10) were prospectively enrolled in this feasibility study and received ICGVA immediately after placement of the aneurysm clips. An intraoperative cranial CT angiography (iCTA) was followed by dynamic perfusion CT scan (iCTP) using a 40-slice, sliding-gantry, CT scanner. The vascular patency of major (aneurysm bearing) arteries, visualisation of arising perforating arteries and brain perfusion after clip application were analysed with both techniques.
Results
The ICGVA was able to visualise blood flow and vascular patency of all major vessels and perforating arteries within the visual field of the microscope, but failed to display vessels located within deeper areas of the surgical field. Even small coverage with brain parenchyma impaired detection of vessels. With iCTA high image quality could be obtained in 7/10 cases of clipped aneurysms. Intraoperative CTA was not sufficiently evaluable in one PICA aneurysm and one case of a previously coiled recurrent aneurysm, due to extensive coil artefacts. Small, perforating arteries could not be detected with iCTA. Intraoperative CTP allowed the assessment of global blood flow and brain perfusion in sufficient quality in 5/10 cases, and enabled adequate intraoperative decision making.
Conclusion
A combination of ICGVA and iCT is feasible, with very good diagnostic imaging quality associated with short acquisition time and little interference with the surgical workflow. Both techniques are complementary rather than competing analysing tools and help to assess information about local (ICGVA/iCTA) as well as regional (iCTA/iCTP) blood flow and cerebral perfusion immediately after clipping of intracranial aneurysms.

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The prognostic significance of traumatic brainstem injury detected on T2-weighted MRI

J Neurosurg 117:722–728, 2012

Magnetic resonance imaging is frequently used to evaluate patients with traumatic brain injury in the acute and subacute setting, and it can detect injuries to the brainstem, which are often associated with poor outcomes. This study was undertaken to determine which MRI and clinical factors provide prognostic information in patients with traumatic brainstem injuries.
Methods
The authors performed a retrospective analysis of cases involving patients admitted to a Level I trauma center who were identified in a prospective database as having suffered traumatic brainstem injury identified on MRI. Patient outcomes were dichotomized to dead/vegetative versus functional groups. Standard demographic data, admission Glasgow Coma Scale (GCS) scores, results of the motor component of the GCS examination at admission and 24 hours later, CT scan findings, and peak intracranial pressure were collected from medical records. Volumetric analysis of each patient’s injuries was performed with T2-weighted and gradient echo sequences. The T2-weighted MRI sequence for each patient was reviewed to determine the anatomical location of injury within the brainstem and whether the injury crossed the midline.
Results
Thirty-six patients who met the study inclusion criteria were identified. At 6-month follow-up, 53% of these patients had poor outcomes and 47% had recovered. Patients with injuries to the medulla or deep bilateral injuries to the pons did not recover. The T2 volumes were found superior to gradient echo sequences in regard to predicting survival (ROC/AUC 0.67, p = 0.07 vs 0.60, p = 0.29, respectively), but neither reached statistical significance. The timing of MR image acquisition did not influence the findings. The time from admission to MRI did not differ significantly between the recovered group and the poor-outcome group (p = 0.52, Mann-Whitney test), and lesion size as measured by T2 volume did not vary with time to scan (R2 = 0.03, p = 0.3, linear regression). Performing a stepwise logistic regression with all the variables yielded the following factors related to recovery: crossing midline, p = 0.0156, OR 0.075; and 24-hour GCS motor score, p = 0.0045, OR = 2.25, c-statistic 0.913. Further examination of these 2 factors disclosed the following: none of 15 patients with midline-crossing lesions and a 24-hour GCS motor score of 4 or less recovered; conversely, 12 of 13 patients with lesions that did not cross midline recovered, regardless of GCS motor score.
Conclusions
Bilateral injury to the pons and medulla as detected on T2-weighted MRI sequences was associated with poor outcome in patients with brainstem injuries; T2 volumes were found superior to gradient echo sequences in regard to predicting survival, but neither reached statistical significance. When MRI findings were coupled with clinical examination findings, a strong correlation existed between poor outcome and the combination of bilateral brainstem injury and a motor GCS score of 4 or less 24 hours after admission.

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Long-term Recordings of Local Field Potentials From Implanted Deep Brain Stimulation Electrodes

Neurosurgery 71:804–814, 2012 

Deep brain stimulation (DBS) of the subthalamic nucleus is an effective treatment for Parkinson disease. However, DBS is not responsive to an individual’s disease state, and programming parameters, once established, do not change to reflect disease state. Local field potentials (LFPs) recorded from DBS electrodes are being investigated as potential biomarkers for the Parkinson disease state. However, no patient data exist about what happens to LFPs over the lifetime of the implant.

OBJECTIVE: We investigated whether LFP amplitude and response to limb movement differed between patients implanted acutely with subthalamic nucleus DBS electrodes and patients implanted 2 to 7 years previously.

METHODS: We recorded LFPs at DBS surgery time (9 subjects), 3 weeks after initial placement (9 subjects), and 2 to 7 years (median: 3.5) later during implanted programmable generator replacement (11 sides). LFP power-frequency spectra for each of 3 bipolar electrode derivations of adjacent contacts were calculated over 5-minute resting and 30-second movement epochs. Monopolar impedance data were used to evaluate trends over time.

RESULTS: There was no significant difference in b-band LFP amplitude between initial electrode implantation (OR) and 3-week post-OR times (P = .94). However, b-band amplitude was lower at implanted programmable generator replacement times than in OR (P = .008) and post-OR recordings (P = .039). Impedance measurements declined over time (P < .001).

CONCLUSION: Postoperative LFP activity can be recorded years after DBS implantation and demonstrates a similar profile in response to movement as during acute recordings, although amplitude may decrease. These results support the feasibility of constructing a closed-loop, patient-responsive DBS device based on LFP activity.

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Management of C2 fractures using Iso-C3D guidance

Acta Neurochir 154 (10):1781-1787, 2012

About 20 % of cervical fractures involve the C2 vertebra. Many surgical techniques have been proposed according to the type of fracture. However, morbidity and mortality of these procedures is often high, which can be attributed to the old age and significant co-morbidities of the affected population and the complex anatomy of C2. To target the latter, several authors have applied iso-C3D guidance for most of the common techniques. We here present our experience using a fixed protocol and iso-C3D guidance in all cases of traumatic C2 fractures.
Methods: Sixteen patients were operated upon between April 2011 and April 2012 using Iso-C3D guidance, following a fixed routine protocol. The screw position was verified by CT-scanning. Intraoperative and clinical parameters were evaluated.
Results: Six patients received anterior lag-screw fixation of odontoid fractures. Two underwent isolated posterior lag-screw fixation of hangman’s fracture. C1 and/or C3 lateral mass, and/or C2 isthmic screws were placed in eight patients. No screw had to be revised, 3 minor breachings of the cortical bone of <2 mm were observed.The same standard protocol for draping, registration of the navigation and Iso-C3D guided drilling could be applied for anterior and posterior procedures, leaving only two variables. This led to rapid acceptance of the technique among OR-staff and surgeons, who felt comfortable with iso-C3D guidance after only five cases.
Conclusions: Iso-C3D guidance is a safe and straightforward technique for anterior and posterior screw placement in the upper cervical spine.

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A Simple and Quantitative Method to Predict Symptomatic Vasospasm After Subarachnoid Hemorrhage Based on Computed Tomography: Beyond the Fisher Scale

Neurosurgery 71:869–876, 2012

Although the Fisher scale is commonly used to grade vasospasm risk in aneurysmal subarachnoid hemorrhage (aSAH) patients, it fails to account for increasing subarachnoid hemorrhage (SAH) thickness.

OBJECTIVE: We developed a simple quantitative scale based on maximal SAH thickness and compared its reproducibility and ability to predict symptomatic vasospasm against the Fisher scale.

METHODS: The incidence of radiographic and symptomatic vasospasm among 250 aSAH patients treated at our institution was investigated. Admission head computed tomography scans were graded according to the Fisher scale and the proposed scale, which assigns a score from 1 to 5 based on a single measurement of maximum SAH thickness. We calculated vasospasm risk per grade for the Fisher scale and the proposed scale, and compared inter- and intraobserver variability for both scales.

RESULTS: Forty-five patients (20.6%) developed symptomatic vasospasm. On the proposed scale, grade 5 patients were at highest risk, with an odds ratio for symptomatic vasospasm of 11 (95% confidence interval [CI] 2.27-53.37). Odds ratios for proposed grades 4 and 3 were 4.63 (95% CI 1.10-19.59) and 3.04 (95% CI 0.85-10.90), respectively. The odds ratio for Fisher grade 3 was 3.3 (0.96-11.30). Mean inter- and intraobserver agreement was greater for the proposed scale in comparison with the Fisher scale (k0.65 and k0.81 vs k0.51 and k0.35, respectively).

CONCLUSION: The new scale accounted for increasing SAH thickness and was superior to the Fisher scale in inter- and intraobserver agreement and in predicting symptomatic vasospasm, particularly among the highest-risk patients.

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Giant anterior clinoidal meningiomas: surgical technique and outcomes

J Neurosurg 117:654–665, 2012

Surgery for giant anterior clinoidal meningiomas that invade vital neurovascular structures surrounding the anterior clinoid process is challenging. The authors present their skull base technique for the treatment of giant anterior clinoidal meningiomas, defined here as globular tumors with a maximum diameter of 5 cm or larger, centered around the anterior clinoid process, which is usually hyperostotic.

Methods. Between 2000 and 2010, the authors performed 23 surgeries in 22 patients with giant anterior clinoidal meningiomas. They used a skull base approach with extradural unroofing of the optic canal, extradural clinoidectomy (Dolenc technique), transdural debulking of the tumor, early optic nerve decompression, and early identification and control of key neurovascular structures.

Results. The mean age at surgery was 53.8 years. The mean tumor diameter was 59.2 mm (range 50–85 mm) with cavernous sinus involvement in 59.1% (13 of 22 patients). The tumor involved the prechiasmatic segment of the optic nerve in all patients, invaded the optic canal in 77.3% (17 of 22 patients), and caused visual impairment in 86.4% (19 of 22 patients). Total resection (Simpson Grade I or II) was achieved in 30.4% of surgeries (7 of 23); subtotal and partial resections were each achieved in 34.8% of surgeries (8 of 23). The main factor precluding total removal was cavernous sinus involvement. There were no deaths. The mean Glasgow Outcome Scale score was 4.8 (median 5) at a mean of 56 months of follow-up. Vision improved in 66.7% (12 of 18 patients) with consecutive neuroophthalmological examinations, was stable in 22.2% (4 of 18), and deteriorated in 11.1% (2 of 18). New deficits in cranial nerve III or IV remained after 8.7% of surgeries (2 of 23).

Conclusions. This modified surgical protocol has provided both a good extent of resection and a good neurological and visual outcome in patients with giant anterior clinoidal meningiomas.

 

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Unilateral Extradural Motor Cortex Stimulation Is Safe and Improves Parkinson Disease at 1 Year

Neurosurgery 71:815–825, 2012

The primary motor cortex, which is part of the corticobasal ganglia loops, may be an alternative option for the surgical treatment of Parkinson disease.

OBJECTIVE: To report on the 1-year safety and efficacy of unilateral extradural motor cortex stimulation in Parkinson disease.

METHODS: A quadripolar electrode strip was extradurally implanted over the motor cortex. Stimulation was continuously delivered through the electrode paddle contralateral to the most affected clinical side. Subjects were prospectively evaluated by the Unified Parkinson’s Disease Rating Scale (UPDRS) and the Parkinson’s Disease Quality of Life Questionnaire. In addition, an extensive cognitive and behavioral assessment and electroencephalogram recording were performed.

RESULTS: Nine patients were included in this study. No surgical complications or adverse events occurred. Moreover, no cognitive or behavioral changes were observed. Under the off-medication condition, the UPDRS III at baseline was decreased by 14.1%, 23.3%, 19.9%, and 13.2%, at 1, 3, 6, and 12 months, respectively. The motor effects were bilateral, appeared after 3 to 4 weeks of stimulation, and outlasted the stimulation itself for 3 to 4 weeks in 1 case of stimulator accidental switching off. The UPDRS IV was decreased by 40.8%, 42.1%, and 35.5% at 1, 3, and 12 months, respectively. The scores on the Parkinson’s Disease Quality of Life Questionnaire were increased at months 3, 6, and 12.

CONCLUSION: Extradural motor cortex stimulation is a safe procedure. After 12 months, the patients demonstrated a moderate improvement of motor symptoms (particularly axial symptoms) and quality of life.

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Who Should Have Surgery for Spinal Stenosis?

Spine 2012 ; 37 : 1791 – 1802

Study Design. Combined prospective randomized controlled trial and observational cohort study of spinal stenosis (SpS) with an as-treated analysis.

Objective. To determine modifiers of the treatment effect (TE) of surgery (the difference between surgical and nonoperative outcomes) for SpS using subgroup analysis.

Summary of Background Data. The Spine Patient Outcomes Research Trial demonstrated a positive surgical TE for SpS at the group level. However, individual characteristics may affect TE. No previous studies have evaluated TE modifiers in SpS.

Methods. SpS patients were treated with either surgery (n = 419) or nonoperative care (n = 235) and were analyzed according to treatment received. Fifty-three baseline variables were used to define subgroups for calculating the time-weighted average TE for the Oswestry Disability Index (ODI) over 4 years (TE = ΔODI surgery – ΔODI nonoperative ). Variables with significant subgroup × treatment interactions ( P < 0.05) were simultaneously entered into a multivariate model to select independent TE predictors.

Results. Other than smokers, all analyzed subgroups including at least 50 patients improved signifi cantly more with surgery than with nonoperative treatment ( P < 0.05). Multivariate analysis demonstrated: baseline ODI ≤ 56 (TE –15.0 vs. –4.4, ODI > 56, P < 0.001), not smoking (TE –11.7 vs. –1.6 smokers, P < 0.001), neuroforaminal stenosis (TE –14.2 vs. –8.7 no neuroforaminal stenosis, P = 0.002), predominant leg pain (TE –11.5 vs. –7.3 predominant back pain, P = 0.035), not lifting at work (TE –12.5 vs . –0.5 lifting at work, P = 0.017), and the presence of a neurological deficit (TE –13.3 vs . –7.2 no neurological deficit, P < 0.001) were associated with greater TE.

Conclusion. With the exception of smokers, patients who met strict inclusion criteria improved more with surgery than with nonoperative treatment, regardless of other specific characteristics. However, TE varied significantly across certain subgroups, and these data can be used to individualize shared decision making discussions about likely outcomes. Smoking cessation should be considered before surgery for SpS.

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Microsurgical clipping of true posterior communicating artery aneurysms

Acta Neurochir (2012) 154:1707–1710

“True” posterior communicating artery (PCOM) aneurysms are rare variants in which the aneurysm arises solely from the PCOM rather than the junction of the internal carotid artery and the PCOM.

Methods It is critical to note that for true PCOM aneurysms, the neck arises distal to the origin of the PCOM and therefore lies in what is traditionally an intra-operative blind spot. The PCOM must be followed posteriorly to visualise the aneurysm neck for microsurgical clipping.

Conclusions A thorough pre-operative understanding of this unique anatomy is essential in minimising morbidity associated with microsurgical clipping of this aneurysm configuration.

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Intraoperative subcortical electrical mapping of optic radiations in awake surgery for glioma involving visual pathways

J Neurosurg 117:466–473, 2012

Preservation of the visual field in glioma surgery, especially avoidance of hemianopia, is crucial for patients’ quality of life, particularly for driving. Recent studies used tractography or cortical occipital stimulation to try to avoid visual deficit. However, optic radiations have not been directly mapped intraoperatively. The authors present, for the first time to their knowledge, a consecutive series of awake surgeries for cerebral glioma with intrasurgical identification and preservation of visual pathways using subcortical electrical mapping.

Methods. Fourteen patients underwent awake resection of a glioma (1 WHO Grade I, 11 WHO Grade II, 2 WHO Grade III) involving the optic radiations. The patients had no presurgical visual field deficit. Intraoperatively, a picture-naming task was used, with presentation of 2 objects situated diagonally on a screen divided into 4 quadrants. An image was presented in the quadrant to be saved and another image was presented in the opposite quadrant. Direct subcortical electrostimulation was repeatedly performed without the patient’s knowledge, until optic radiations were identified (transient visual disturbances). All patients underwent an objective visual field assessment 3 months after surgery.

Results. All patients experienced visual symptoms during stimulation. These disturbances led the authors to stop the tumor resection at that level. Postoperatively, only 1 patient had a permanent hemianopia, despite an expected quadrantanopia in 12 cases. The mean extent of resection was 93.6% (range 85%–100%).

Conclusions. Online identification of optic radiations by direct subcortical electrostimulation is a reliable and effective method to avoid permanent hemianopia in surgery for gliomas involving visual pathways.

 

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Endoscopic Endonasal Transclival Approach to the Jugular Tubercle

Neurosurgery 71[ONS Suppl 1]:ons146–ons159, 2012

The jugular tubercle is a rounded bony prominence that arises from the inferolateral margin of the clivus. In a previous publication, we described the surgical anatomy of the expanded endonasal approach to the jugular tubercle.

OBJECTIVE: To illustrate the translation of laboratory work to the operating room describing the anatomic and technical nuances of the endonasal approach to the jugular tubercle.

METHODS: We review the relevant surgical anatomy needed to perform an endonasal approach to the jugular tubercle, and we select 4 different lesions to illustrate the application of our laboratory findings.

RESULTS: In the first case, exposure and partial drilling of the jugular tubercle was critical to gain an adequate corridor to the meningioma, particularly to its inferolateral margin. This allowed for early devascularization, safe extracapsular dissection, and preservation of surrounding neurovascular structures. In addition, the jugular tubercle was hyperostotic and its resection, along with generous dural removal, provided a grade I Simpson tumor resection. In the second (chondrosarcoma) and third (chordoma) cases, the jugular tubercle was infiltrated by tumor, and consequently its complete resection was essential to achieve total tumor removal. In the last case, an unusual adrenocorticotropic hormone-secreting adenoma recurrence at the jugular tubercle region, the technical modification of the transclival approach presented here was successfully applied to achieve complete resection and Cushing disease remission.

CONCLUSION: The transjugular tubercle variant of the expanded endonasal transclival approach allows for direct access to ventrolateral lesions in the inferior clival/petroclival region with no cerebral or cerebellar retraction, or cranial nerve manipulation during the approach.

 

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Independent predictors for recurrence of chronic subdural hematoma

Acta Neurochir (2012) 154:1541–1548 DOI 10.1007/s00701-012-1399-9

Chronic subdural hematoma is characterized by blood in the subdural space that evokes an inflammatory reaction. Numerous factors potentially associated with recurrence of chronic subdural hematoma have been reported, but these factors have not been sufficiently investigated. In this study, we evaluated the independent risk factors of recurrence.

Methods We analyzed data for 420 patients with chronic subdural hematoma treated by the standard surgical procedure for hematoma evacuation at our institution.

Results Ninety-two (21.9 %) patients experienced at least one recurrence of chronic subdural hematoma during the study period. We did not identify any significant differences between chronic subdural hematoma recurrence and current antiplatelet therapy. The recurrence rate was 7 % for the homogeneous type, 21 % for the laminar type, 38 % for the separated type, and 0 % for the trabecular type. The rate of recurrence was significantly lower in the homogeneous and trabecular type than in the laminar and separated type. We performed a multivariate logistic regression analysis and found that postoperative midline shifting (OR, 3.6; 95 % CI, 1.618-7.885; p00.001), diabetes mellitus (OR, 2.2; 95 % CI, 1.196-3.856; p=0.010), history of seizure (OR, 2.6; 95 % CI, 1.210-5.430; p=0.014), width of hematoma (OR, 2.1; 95 % CI, 1.287-3.538; p=0.003), and anticoagulant therapy (OR, 2.7; 95 % CI, 1.424-6.960; p=0.005) were independent risk factors for the recurrence of chronic subdural hematoma.

Conclusions We have shown that postoperative midline shifting (≥5 mm), diabetes mellitus, preoperative seizure, preoperative width of hematoma (≥20 mm), and anticoagulant therapy were independent predictors of the recurrence of chronic subdural hematoma. According to internal architecture of hematoma, the rate of recurrence was significantly lower in the homogeneous and the trabecular type than the laminar and separated type.

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Visual Outcomes After Surgical Treatment of Adult Craniopharyngiomas

Neurosurgery 71:715–721, 2012 DOI: 10.1227/NEU.0b013e318262146b

Craniopharyngiomas (CRPs) often cause visual deterioration (VD) due to the close vicinity of the optic apparatus.

OBJECTIVE: To evaluate longitudinal visual outcomes after surgery of CRP and determine the prognostic factors thereof.

METHODS: One hundred forty-six adult patients who underwent surgery for newly diagnosed CRP were retrospectively reviewed. There were 87 male patients (60%), and the median age was 41 years (range, 18-75). The mean follow-up duration was 88.7 months (range, 24-307). A visual impairment score was used to assess the short-term (,1 month) and long-term (.2 years) visual outcomes.

RESULTS: Gross total removal was performed in 53 patients (36%), and tumor recurrence occurred in 40 patients (27%). The average preoperative, short- and longterm visual impairment scores were 44.4, 38.5, and 38.1, respectively, on a 0- to 100-point scale (with 100 indicating the worst vision). Short- and long-term VD occurred in 28 (19%) and 39 patients (27%), respectively. Subtotal removal (STR) alone (P = .010; OR = 4.8), short-termVD (P<.001; OR = 39.7), and tumor recurrence (P<.001; OR = 28.2) were significant risk factors for long-term VD in the multivariate analysis. Patients undergoing STR alone had higher tumor recurrence rates in comparison with those who underwent gross total removal or STR with adjuvant therapy (P < .001).

CONCLUSION: Short-term VD secondary to the surgical insult and the recurrence of the tumor were strong predictors of long-term visual outcomes after surgical treatment for CRP. STR alone may be an ineffective strategy for achieving tumor control and optimal visual outcomes in patients with CRP.

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Surgery for vestibular schwannomas: a systematic review of complications by approach

Neurosurg Focus 33 (3):E14, 2012

Various studies report outcomes of vestibular schwannoma (VS) surgery, but few studies have compared outcomes across the various approaches. The authors conducted a systematic review of the available data on VS surgery, comparing the different approaches and their associated complications.

Methods. MEDLINE searches were conducted to collect studies that reported information on patients undergoing VS surgery. The authors set inclusion criteria for such studies, including the availability of follow-up data for at least 3 months, inclusion of preoperative and postoperative audiometric data, intraoperative monitoring, and reporting of results using established and standardized metrics. Data were collected on hearing loss, facial nerve dysfunction, persistent postoperative headache, CSF leak, operative mortality, residual tumor, tumor recurrence, cranial nerve (CN) dysfunction involving nerves other than CN VII or VIII, and other neurological complications. The authors reviewed data from 35 studies pertaining to 5064 patients who had undergone VS surgery.

Results. The analyses for hearing loss and facial nerve dysfunction were stratified into the following tumor categories: intracanalicular (IC), size (extrameatal diameter) < 1.5 cm, size 1.5–3.0 cm, and size > 3.0 cm. The middle cranial fossa approach was found to be superior to the retrosigmoid approach for hearing preservation in patients with tumors < 1.5 cm (hearing loss in 43.6% vs 64.3%, p < 0.001). All other size categories showed no significant difference between middle cranial fossa and retrosigmoid approaches with respect to hearing loss. The retrosigmoid approach was associated with significantly less facial nerve dysfunction in patients with IC tumors than the middle cranial fossa method was; however, neither differed significantly from the translabyrinthine corridor (4%, 16.7%, 0%, respectively, p < 0.001). The middle cranial fossa approach differed significantly from the translabyrinthine approach for patients with tumors < 1.5 cm, whereas neither differed from the retrosigmoid approach (3.3%, 11.5%, and 7.2%, respectively, p = 0.001). The retrosigmoid approach involved less facial nerve dysfunction than the middle cranial fossa or translabyrinthine approaches for tumors 1.5–3.0 cm (6.1%, 17.3%, and 15.8%, respectively; p < 0.001). The retrosigmoid approach was also superior to the translabyrinthine approach for tumors > 3.0 cm (30.2% vs 42.5%, respectively, p < 0.001). Postoperative headache was significantly more likely after the retrosigmoid approach than after the translabyrinthine approach, but neither differed significantly from the middle cranial fossa approach (17.3%, 0%, and 8%, respectively; p < 0.001). The incidence of CSF leak was significantly greater after the retrosigmoid approach than after either the middle cranial fossa or translabyrinthine approaches (10.3%, 5.3%, 7.1%; p = 0.001). The incidences of residual tumor, mortality, major non-CN complications, residual tumor, tumor recurrence, and dysfunction of other cranial nerves were not significantly different across the approaches.

Conclusions. The middle cranial fossa approach seems safest for hearing preservation in patients with smaller tumors. Based on the data, the retrosigmoid approach seems to be the most versatile corridor for facial nerve preservation for most tumor sizes, but it is associated with a higher risk of postoperative pain and CSF fistula. The translabyrinthine approach is associated with complete hearing loss but may be useful for patients with large tumors and poor preoperative hearing.

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C1-C2 Posterior Fixation: Are 4 Screws Better Than 2?

Neurosurgery 71[ONS Suppl 1]:ons86–ons95, 2012 

Several types of C1-C2 fixation techniques have been described over the years in order to treat atlantoaxial instability.

OBJECTIVE: To compare the pros and cons of the most popular C1-C2 posterior fixation used today: C1 lateral mass-C2 pedicle screw and rods (Harms) and transarticular screw (Magerl) fixations.

METHODS: Retrospective review of 122 patients who underwent Harms or Magerl fixation for atlantoaxial instability. Surgical, clinical, and radiological outcomes were compared in the 2 groups.

RESULTS: 123 operations were performed, of which 47 were by the Harms technique (group H) and 76 by the Magerl technique (group M). No significant differences were found in duration of surgery, blood loss, postoperative pain, and length of hospitalization. Postoperatively, neck pain, C2-radiculopathy, and hand function improved in both groups, with better, but not statistically significant, results for group H. The intraoperative complication rate was 2.1% in group H and 21% in group M (P < .05); postoperative complication rate was 10.6% in group H and 21%in groupM(P>.05). The major complications were vertebral artery injury (2.1% in group H, 13.1% in group M, P = .05) and screw fracture (2.1% in group H, 9.2% in group M, P > .05). Fusion rate at the end of follow-up was not significantly higher in group H. C1-C2 range of movements in flexion/extension at the end of follow-up was lower in group H (P = .017).

CONCLUSION: Magerl with posterior wiring and Harms techniques are both effective options for stabilizing the atlantoaxial complex. However, the Harms technique appears to be safer, to have fewer complications, and to demonstrate a more robust long-term fixation.

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Intracranial hypotension producing reversible coma

J Neurosurg 117:615–628, 2012

Intracranial hypotension is a disorder of CSF hypovolemia due to iatrogenic or spontaneous spinal CSF leakage. Rarely, positional headaches may progress to coma, with frequent misdiagnosis. The authors review reported cases of verified intracranial hypotension–associated coma, including 3 previously unpublished cases, totaling 29. Most patients presented with headache prior to neurological deterioration, with positional symptoms elicited in almost half. Eight patients had recently undergone a spinal procedure such as lumbar drainage. Diagnostic workup almost always began with a head CT scan. Subdural collections were present in 86%; however, intracranial hypotension was frequently unrecognized as the underlying cause. Twelve patients underwent one or more procedures to evacuate the collections, sometimes with transiently improved mental status. However, no patient experienced lasting neurological improvement after subdural fluid evacuation alone, and some deteriorated further. Intracranial hypotension was diagnosed in most patients via MRI studies, which were often obtained due to failure to improve after subdural hematoma (SDH) evacuation. Once the diagnosis of intracranial hypotension was made, placement of epidural blood patches was curative in 85% of patients. Twenty-seven patients (93%) experienced favorable outcomes after diagnosis and treatment; 1 patient died, and 1 patient had a morbid outcome secondary to duret hemorrhages. The literature review revealed that numerous additional patients with clinical histories consistent with intracranial hypotension but no radiological confirmation developed SDH following a spinal procedure. Several such patients experienced poor outcomes, and there were multiple deaths. To facilitate recognition of this treatable but potentially life-threatening condition, the authors propose criteria that should prompt intracranial hypotension workup in the comatose patient and present a stepwise management algorithm to guide the appropriate diagnosis and treatment of these patients.

 

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Frameless image-guided stereotaxy with real-time visual feedback for brain biopsy

Acta Neurochir (2012) 154:1663–1667 DOI 10.1007/s00701-012-1425-y

Frame-based stereotaxy remains the “gold standard” for cerebral biopsies and functional neurosurgery though new frameless stereotactic systems are evolving continually. As the technique of frameless stereotaxy gains increasing acceptance among neurosurgeons, this study assesses the feasibility of a system for frameless imageguided stereotaxy.

Methods All patients biopsied for intracranial lesions between February 2007 and August 2010 using the BrainLAB VarioGuide frameless stereotactic system were evaluated prospectively. Prior to surgery, patients underwent magnetic resonance (MR) imaging; additionally, fluoroethyl-tyrosine (FET)-positron emission tomography (PET) images were acquired and fused to MR images in selected cases. Biopsy trajectory length, lesion volume, procedure duration, and diagnostic yield were assessed.

Results Ninety-six diagnostic biopsies in 91 patients were evaluated. Lesion volume ranged from 0.17 to 121.8 cm3; trajectory length from 25.3 to 101.9 mm. Diagnostic yield was 93.8%. Mean operation time from skin incision to wound closure was 42 min; in the operating room, it was 99 min.

Conclusions Clinical experience indicates VarioGuide to be safe and accurate. Reachable range of lesion localisation appears to be comparable to a frame-based stereotaxy system. Operation times are brief. The unique design of this frameless stereotactic system allows real-time visual feedback of needle positioning.

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