Category: Surgical technique

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Evaluation of Serial Intraoperative Surgical Microscope-Integrated Intraoperative Near-Infrared Indocyanine Green Videoangiography in Patients With Cerebral Arteriovenous Malformations

Neurosurgery 70[ONS Suppl 1]:ons34–ons43, 2012 DOI: 10.1227/NEU.0b013e31822d9749 

With the use of indocyanine green (ICG) as a novel fluorescent dye, fluorescence angiography has recently reemerged as a viable option.

OBJECTIVE: To show the result of ICG videoangiography in cases of cerebral arteriovenous malformations.

METHODS: Twenty-seven ICG videoangiography procedures were performed in 11 patients with cerebral arteriovenous malformations. Intraoperative digital subtraction angiography (DSA) was performed 27 times in these patients. The timing of intraoperative DSA was before dissection, after clipping of feeders, and after dissection of the nidus.

RESULTS: The procedures were performed in 4.7 ± 1.4 minutes (mean ± SD; n = 27 minutes), whereas intraoperative digital subtraction angiography was performed for a mean of 16.6 ± 3.8 minutes (n = 27 minutes). In predissection studies, feeders were visualized by ICG in 3 of 9 cases. The nidus was visualized in all 9 cases, and drainers were visualized in 8. Intraoperative DSA visualized the feeders, nidus, and drainers in all 9 cases. After clipping of feeders, ICG videoangiography showed flow reduction of the nidus in 7 of 7 cases. Intraoperative DSA also showed that finding in 9 of 9 cases. After total dissection of the nidus, all cases disclosed that the drainers were without ICG filling. Intraoperative DSA also showed that result in all of the cases. Unexpected residual nidus was not visualized in our series with either method.

CONCLUSION: We found that ICG videoangiography is helpful for resecting cerebral arteriovenous malformation. It is especially effective in visualizing the nidus and superficial drainers, as well as changes in flow after clipping or coagulating of feeders.

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Mini-open lateral approach for thoracic disc herniation

J Neurosurg Spine 16:264–279, 2012. DOI: 10.3171/2011.10.SPINE11291

Symptomatic herniated thoracic discs remain a surgical challenge and historically have been associated with significant complications. While neurological outcomes have improved with the abandonment of decompressive laminectomy, the attempt to minimize surgical complications and associated morbidities continues through less invasive approaches. Many of these techniques, such as thoracoscopy, have not been widely adopted due to technical difficulties. The current study was performed to examine the safety and early results of a minimally invasive lateral approach for symptomatic thoracic herniated intervertebral discs.

Methods. Sixty patients from 5 institutions were treated using a mini-open lateral approach for 75 symptomatic thoracic herniated discs with or without calcification. The mean age was 57.9 years (range 23–80 years), and 53.3% of the patients were male. Treatment levels ranged from T4–5 to T11–12, with 1–3 levels being treated (mean 1.3 levels). The most common levels treated were T11–12 (14 cases [18.7%]), T7–8 (12 cases [16%]), and T8–9 (12 cases [16%]). Symptoms included myelopathy in 70% of cases, radiculopathy in 51.7%, axial back pain in 76.7%, and bladder and/or bowel dysfunction in 26.7%. Instrumentation included an interbody spacer in all but 6 cases (10%). Supplemental internal fixation included anterolateral plating in 33.3% of cases and pedicle screws in 10%; there was no supplemental internal fixation in 56.7% of cases. Follow-up ranged from 0.5 to 24 months (mean 11.0 months).

Results. The median operating time, estimated blood loss, and length of stay were 182 minutes, 290 ml, and 5.0 days, respectively. Four major complications occurred (6.7%): pneumonia in 1 patient (1.7%); extrapleural free air in 1 patient (1.7%), treated with chest tube placement; new lower-extremity weakness in 1 patient (1.7%); and wound infection in posterior instrumentation in 1 patient (1.7%). Reoperations occurred in 3 cases (5%): one for posterior reexploration, one for infection in posterior instrumentation, and one for removal of symptomatic residual disc material. Back pain, measured using the visual analog scale, improved 60% from the preoperative score to the last follow-up, that is, from 7.8 to 3.1. Excellent or good overall outcomes were achieved in 80% of the patients, a fair or unchanged outcome resulted in 15%, and a poor outcome occurred in 5%. Moreover, myelopathy, radiculopathy, axial back pain, and bladder and/or bowel dysfunction improved in 83.3%, 87.0%, 91.1%, and 87.5% of cases, respectively.

Conclusions. The authors’ early experience with a large multicenter series suggested that the minimally invasive lateral approach is a safe, reproducible, and efficacious procedure for achieving adequate decompression in thoracic disc herniations in a less invasive manner than conventional surgical techniques and without the use of endoscopes. Symptom resolution was achieved at similar rates using this approach as compared with the most efficacious techniques in the literature, and with fewer complications in most circumstances.

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Microscope-Integrated Quantitative Analysis of Intraoperative Indocyanine Green Fluorescence Angiography for Blood Flow Assessment

Neurosurgery 70[ONS Suppl 1]:ons65–ons74, 2012 DOI: 10.1227/NEU.0b013e31822f7d7c

Intraoperative measurements of cerebral blood flow are of interest during vascular neurosurgery. Near-infrared indocyanine green (ICG) fluorescence angiography was introduced for visualizing vessel patency intraoperatively. However, quantitative information has not been available.

OBJECTIVE: To report our experience with a microscope with an integrated dynamic ICG fluorescence analysis system supplying semiquantitative information on blood flow.

METHODS: We recorded ICG fluorescence curves of cortex and cerebral vessels using software integrated into the surgical microscope (Flow 800 software; Zeiss Pentero) in 30 patients undergoing surgery for different pathologies. The following hemodynamic parameters were assessed: maximum intensity, rise time, time to peak, time to halfmaximal fluorescence, cerebral blood flow index, and transit times from arteries to cortex.

RESULTS: For patients without obvious perfusion deficit, maximum fluorescence intensity was 177.7 arbitrary intensity units (AIs; 5-mg ICG bolus), mean rise time was 5.2 seconds (range, 2.9-8.2 seconds; SD, 1.3 seconds), mean time to peak was 9.4 seconds (range, 4.9-15.2 seconds; SD, 2.5 seconds), mean cerebral blood flow index was 38.6 AI/s (range, 13.5-180.6 AI/s; SD, 36.9 seconds), and mean transit time was 1.5 seconds (range, 360 milliseconds-3 seconds; SD, 0.73 seconds). For 3 patients with impaired cerebral perfusion, time to peak, rise time, and transit time between arteries and cortex were markedly prolonged (.20, .9 , and .5 seconds). In single patients, the degree of perfusion impairment could be quantified by the cerebral blood flow index ratios between normal and ischemic tissue. Transit times also reflected blood flow perturbations in arteriovenous fistulas.

CONCLUSION: Quantification of ICG-based fluorescence angiography appears to be useful for intraoperative monitoring of arterial patency and regional cerebral blood flow.

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Intra-arterial Indocyanine Green Angiography in Spinal AVFs

SPINE Volume 37, Number 4, pp E264–E267

We first present 2 cases of spinal arteriovenous fistulae (AVFs) successfully treated with the help of intra-arterial indocyanine green (ICG) angiography.

Objective. To demonstrate the efficacy of intra-arterial ICG angiography in spinal AVFs compared with the role of intravenous ICG injection and intraoperative digital subtraction angiography (DSA).

Summary of Background Data. Intravenous ICG fluorescent angiography is an emerging intraoperative tool to recognize vascular anatomy. The technique is quite simple and provides real-time vascular hemodynamics in the operative field. However, it takes time for the ICG to be washed out; therefore, repeat studies are somewhat tedious and time consuming, especially in spinal AVFs with multiple shunts/drainer. In this setting, intraoperative DSA has still been the standard to confirm the complete obliteration, although this has a risk of radiation exposure and renal failure.

Methods. Two patients, a 46-year-old man with spinal dural AVF at the cervicomedullary junction and a 68-year-old woman with spinal perimedullary AVF at the conus medullaris, were surgically treated with the help of intra-arterial ICG angiography.

Results. We introduced a catheter into the target artery and injected 0.05 mg ICG in 2 mL of normal saline in multiple, short intervals. This approach enabled us to detect the residual shunt/drainer and confirm complete obliteration. With this technique, a tiny amount of ICG was used in the operative field to clearly label only the affected vessels. Intraoperative DSA was not performed in these cases.

Conclusion. These cases demonstrate that intra-arterial ICG angiography is a powerful tool for visualizing spinal AVFs in terms of addressing the disadvantages of intravenous ICG injection and intraoperative DSA.

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The quiet revolution: retractorless surgery for complex vascular and skull base lesions

J Neurosurg 116:291–300, 2012. DOI: 10.3171/2011.8.JNS101896

Smaller operative exposures, endoscopic approaches, and minimally invasive neurosurgery have emerged as a dominant trend in the modern era. In keeping with this evolution, the authors have recently eliminated the use of fixed retractors, instead employing dynamic retraction, with the use of handheld instruments. In the present study, the authors report the results of applying this strategy to challenging vascular and skull base lesions.

Methods. This 6-month study prospectively analyzed the use of retractorless surgery in a consecutive series of 223 patients with intracranial vascular or skull base lesions undergoing craniotomy. A single surgeon performed all operations.

Results. The microsurgical approaches (in descending order of frequency) included an orbitozygomatic craniotomy (77 patients [35%]), frontal (36 patients [16%]), retrosigmoid (27 patients [12%]), interhemispheric (16 patients [7%]), and lateral supracerebellar (15 patients [7%]). The most common lesions were aneurysms (83 lesions overall [37%]), 18 of which required a bypass. Of 159 vascular lesions, there were also 46 cavernous malformations (29%). Meningiomas were the most common skull base tumors (37 cases [58%]). Of the 223 patients, 7 cases of various vascular and skull base lesions required fixed retraction. Therefore, 97% of the cases were successfully treated without a self-retaining retractor system.

Conclusions. Fixed retraction can be supplanted by dynamic retraction with surgical instruments, limiting the risk of retractor-induced tissue edema and injury. This quiet revolution has precipitated a major change in surgical techniques. Extensive dissection of arachnoidal planes, careful placement of the handheld suction device, patient positioning that enhances gravity retraction, the refinement of microsurgical instrumentation, and appropriate selection of the operative corridor all serve to obviate the need for fixed retraction in most intracranial procedures. Retractorless neurosurgery is an achievable goal, even when complex lesions of the vasculature and skull base are being treated.

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Image-Guided Thoracoscopic Resection of Thoracic Dumbbell Nerve Sheath Tumors

Neurosurgery 70:461–468, 2012 DOI: 10.1227/NEU.0b013e318235ba96

Surgical removal of dumbbell nerve sheath tumors (NSTs) remains challenging because these neoplasms occupy ≥ 2 spinal and extraspinal spaces. The presence of intraspinal extension, tumor dimension, and/or its location within the thoracic cavity have previously made the resection of these types of neoplasms difficult.

OBJECTIVE: To describe the feasibility of performing minimally invasive thoracoscopic surgery, as facilitated by an image guidance system (IGS), to achieve gross total resection of select dumbbell NSTs located in the thoracic spine.

METHODS: The 3 cases presented here contained small intraspinal or foraminal components. Preoperative symptoms included Horner syndrome and back and chest wall pain. We used IGS to help guide the complete thoracoscopic resection of select dumbbell NSTs, consisting of extradural, intraforaminal, and paravertebral tumor components, which previously would have been challenging with only a thoracoscopic approach.

RESULTS: IGS provided continuous intraoperative anatomic orientation to achieve gross total resection in all 3 cases. All surgical and postsurgical outcomes were satisfactory; preoperative symptoms improved or resolved; and no adverse events were observed.

CONCLUSION: Thoracic dumbbell NSTs that have small intraspinal or foraminal components could be resected thoracoscopically when facilitated by IGS. Image-guided thoracoscopic resection of such dumbbell tumors may not only improve the precision of resection, reduce recurrence, and avoid the need for spinal reconstruction but also obviate the need for more invasive or simultaneous posterior procedures. The IGS enhances the accuracy and safety of 2-dimensional thoracoscopic surgery and may reduce its learning curve.

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Comparative Evaluation of Percutaneous Retrogasserian Glycerol Rhizolysis and Radiofrequency Thermocoagulation Techniques in the Management of Trigeminal Neuralgia

Neurosurgery 70:407–413, 2012 DOI: 10.1227/NEU.0b013e318233a85f

Among the percutaneous procedures for the treatment of trigeminal neuralgia, percutaneous anhydrous glycerol rhizolysis (PRGR) and radiofrequency (RF) ablation of trigeminal neuralgia have stood the test of time.

OBJECTIVE: A prospective study was conducted to compare PRGR and RF ablation techniques in patients with trigeminal neuralgia in terms of (1) efficacy of pain relief, (2) duration of pain relief and (3) side effects.

METHODS: All patients presenting to our pain clinic for the first time for the treatment of trigeminal neuralgia were enrolled to receive either PRGR or RF ablation; the treatment was chosen by the patient. Demographic data, magnetic resonance imaging scan, relevant medical disease, amount of anhydrous glycerol, lesion temperature, and total duration of RF were noted. The presence or absence of cerebrospinal fluid egress, immediate pain relief, duration of pain-free period, need for repeat injection or additional peripheral nerve block, and recurrence of pain were also noted. The degree of pain relief was recorded every 3 months. Any complications during the procedure and side effects were also recorded.

RESULTS: Seventy-nine patients underwent either PRGR (n = 40) or RF thermocoagulation (n = 39). A total of 23 patients (58.9%) in the PRGR group and 33 patients (84.6%) in the RF group experienced excellent pain relief. The mean duration of excellent pain relief in the PRGR and RF groups was comparable. By the end of the study period, 39.1% patients in the PRGR group and 51.5% patients in the RF group experienced recurrence of pain.

CONCLUSION: Both PRGR and RF techniques can achieve acceptable pain relief with minimal side effects.

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Accuracy of Diffusion Tensor Magnetic Resonance Imaging-Based Tractography for Surgery of Gliomas Near the Pyramidal Tract

Neurosurgery 70:283–294, 2012 DOI: 10.1227/NEU.0b013e31823020e6

Diffusion tensor (DT) imaging-based fiber tracking is a noninvasive magnetic resonance technique that can delineate the course of white matter fibers.

OBJECTIVE: To evaluate the accuracy and usefulness of this DT imaging-based fiber tracking for surgery in patients with gliomas near the pyramidal tract (PT).

METHODS: Subjects comprised 32 patients with gliomas near the PT. DT imagingbased fiber tracks of the PT were generated before and within 3 days after surgery in all patients. A tractography-integrated navigation system was used during the operation. Cortical and subcortical motor-evoked potentials (MEPs) were also monitored during resection to maximize the preservation of motor function. The threshold intensity for subcortical MEPs was examined by searching the stimulus points and changing the stimulus intensity. Minimum distance between the resection border and the illustrated PT was measured on postoperative tractography.

RESULTS: In all subjects, DT imaging-based tractography of the PT was successfully performed, preoperatively demonstrating the relationship between tumors and the PT. With the use of the tractography-integrated navigation system and intraoperative MEPs, motor function was preserved postoperatively in all patients. A significant correlation was seen between threshold intensity for subcortical MEPs and the distance between the resection border and PT on postoperative DT imaging.

CONCLUSION: DT imaging-based fiber tracking is a reliable and accurate method for mapping the course of subcortical PTs. Fiber tracking and intraoperative MEPs were useful for preserving motor function in patients with gliomas near the PT.

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A Prospective, Randomized Trial Comparing Expansile Cervical Laminoplasty and Cervical Laminectomy and Fusion for Multilevel Cervical Myelopathy

Neurosurgery 70:264–277, 2012 DOI: 10.1227/NEU.0b013e3182305669

Controversy exists as to the best posterior operative procedure to treat multilevel compressive cervical spondylotic myelopathy.

OBJECTIVE: To determine clinical, radiological, and patient satisfaction outcomes between expansile cervical laminoplasty (ECL) and cervical laminectomy and fusion (CLF).

METHODS: We performed a prospective, randomized study of ECL vs CLF in patients suffering from cervical spondylotic myelopathy. End points included the Short Form-36, Neck Disability Index, Visual Analog Scale, modified Japanese Orthopedic Association score, Nurick score, and radiographic measures.

RESULTS: A survey of academic North American spine surgeons (n = 30) demonstrated that CLF is the most commonly used (70%) posterior procedure to treat multilevel spondylotic cervical myelopathy. A total of 16 patients were randomized: 7 to CLF and 9 to ECL. Both groups showed improvements in their Nurick grade and Japanese Orthopedic Association score postoperatively, but only the improvement in the Nurick grade for the ECL group was statistically significant (P < .05). The cervical range of motion between C2 and C7 was reduced by 75% in the CLF group and by only 20% in the ECL group in a comparison of preoperative and postoperative range of motion. The overall increase in canal area was significantly (P < .001) greater in the CLF group, but there was a suggestion that the adjacent level was more narrowed in the CLF group in as little as 1 year postoperatively.

CONCLUSION: In many respects, ECL compares favorably to CLF. Although the patient numbers were small, there were significant improvements in pain measures in the ECL group while still maintaining range of motion. Restoration of spinal canal area was superior in the CLF group.

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Midterm outcome after a microsurgical unilateral approach for bilateral decompression of lumbar degenerative spondylolisthesis

J Neurosurg Spine 16:68–76, 2012. DOI: 10.3171/2011.7.SPINE11222

The aim of this study was to evaluate the results and effectiveness of bilateral decompression via a unilateral approach in the treatment of lumbar degenerative spondylolisthesis (DS).

Methods. Operations were performed in 84 selected patients (mean age 62.1 ± 10 years) with lumbar DS between the years 2001 and 2008. The selection criteria included lower back pain with or without sciatica, neurogenic claudication that had not improved after at least 6 months of conservative treatment, and a radiological diagnosis of Grade I DS and lumbar stenosis. Decompression was performed at 3 levels in 15.5%, 2 levels in 54.8%, and 1 level in 29.7% of the patients with 1 level of spondylolisthesis. All patients were followed up for at least 24 months. For clinical evaluations, a visual analog scale, Oswestry Disability Index (ODI), and Neurogenic Claudication Outcome Score (NCOS) were used. Spinal canal size and (neutral and dynamic) slip percentages were measured both pre- and postoperatively.

Results. Neutral and dynamic slip percentages did not significantly change after surgery (p = 0.67 and p = 0.63, respectively). Spinal canal size increased from 50.6 ± 5.9 to 102.8 ± 9.5 mm2 (p < 0.001). The ODI decreased significantly in both the early and late follow-up evaluations, and good or excellent results were obtained in 64 cases (80%). The NCOS demonstrated significant improvement in the late follow-up results (p < 0.001). One patient (1.2%) required secondary fusion during the follow-up period.

Conclusions. Postoperative clinical improvement and radiological findings clearly demonstrated that the unilateral approach for treating 1-level and multilevel lumbar spinal stenosis with DS is a safe, effective, and minimally invasive method in terms of reducing the need for stabilization.

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Localization of Primary Language Areas by Arcuate Fascicle Fiber Tracking

Neurosurgery 70:56–65, 2012 DOI: 10.1227/NEU.0b013e31822cb882

To reduce the risk of disabling postoperative functional deficit in patients with lesions in the dominant hemisphere, information about the localization of eloquent language areas is mandatory.

OBJECTIVE: To demonstrate the feasibility of arcuate fascicle (AF) tractography for proper localization of eloquent language areas in the superior temporal (STG) and inferior frontal gyrus (IFG).

METHODS: Between January and June 2010, we performed surgery in 13 patients with highly eloquent lesions with close spatial relationship to the primary language areas. All of them received preoperative diffusion tensor imaging for AF tractography. The STG and IFG were delineated at the ends of the AF. Five patients underwent functional magnetic resonance imaging of the primary language areas. The results were compared with tractography.

RESULTS: Tractography of the AF without prior knowledge of the localization of the STG and IFG was feasible in all cases. In the cases with functional magnetic resonance imaging, the activation maps matched the tractography results. In all but 1 patient, preservation of the primary language areas was possible, proven by the good neurological outcome. One patient suffered from a language dysfunction caused by a lesion in the medial and inferior temporal gyrus along the surgical pathway.

CONCLUSION: Tractography of the AF is a useful tool for identification of parts of the main primary language areas. Using tractography as a localization procedure to determine the primary language areas aids in the delineation of the STG and IFG and thus may help reduce the risk of postoperative permanent neurological deficit.

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Experience in Using the Excimer Laser–Assisted Nonocclusive Anastomosis Nonocclusive Bypass Technique for High-Flow Revascularization: Mannheim-Helsinki Series of 64 Patients

Neurosurgery 70:49–55, 2012 DOI: 10.1227/NEU.0b013e31822cb979

The excimer laser–assisted nonocclusive anastomosis (ELANA) technique enables large-caliber bypass revascularization without temporary occlusion of the parent artery.

OBJECTIVE: To present the surgical experience of 2 bypass centers using ELANA in the treatment of complex intracranial lesions.

METHODS: Between July 2002 and December 2007, 64 consecutive patients (37 in Germany and 27 in Finland) were selected for high-flow bypass surgery with ELANA. Modified Rankin Scale, a bypass success rate, and the success rate of the laser arteriotomy were assessed.

RESULTS: In 66 surgeries for 64 intent-to-treat patients, 58 ELANA procedures were completed successfully. A favorable outcome (postoperative modified Rankin Scale score less than or equal to preoperative modified Rankin Scale) at 3 months was achieved in 43 of 56 patients (77%) with anterior circulation lesions (37 of the 43 patients had aneurysms, 4 had ischemia, and 2 received a bypass before tumor removal) and only in 2 of 8 patients (25%) with posterior circulation aneurysms. Perioperative (, 7 days) mortality for anterior and posterior circulation aneurysms was 6% and 50%, respectively. At the 3-month follow-up, 12% and 63% of patients with anterior and posterior circulation aneurysms, respectively, were dead. The success rate of the laser arteriotomy was 70%. Another 14% were retrieved manually after a nearly complete laser arteriotomy.

CONCLUSION: The ELANA procedure requires a meticulous and careful operative technique. Morbidity and especially mortality rates, usually unrelated to ELANA, are comparable to those of contemporary series of conventional high-flow revascularization operations. This underscores the overall complexity of treating neurovascular pathologies by high-flow bypasses.

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The Barrow Ruptured Aneurysm Trial

J Neurosurg 116:135–144, 2012.DOI: 10.3171/2011.8.JNS101767

The purpose of this ongoing study is to compare the safety and efficacy of microsurgical clipping and endovascular coil embolization for the treatment of acutely ruptured cerebral aneurysms and to determine if one treatment is superior to the other by examining clinical and angiographic outcomes. The authors examined the null hypothesis that no difference exists between the 2 treatment modalities in the setting of subarachnoid hemorrhage (SAH). The current report is limited to the clinical results at 1 year after treatment.

Methods. The authors screened 725 patients with SAH, resulting in 500 eligible patients who were enrolled prospectively in the study after giving their informed consent. Patients were assigned in an alternating fashion to surgical aneurysm clipping or endovascular coil therapy. Intake evaluations and outcome measurements were collected by nurse practitioners independent of the treating surgeons. Ultimately, 238 patients were assigned to aneurysm clipping and 233 to coil embolization. The 2 treatment groups were well matched. There were no anatomical exclusions. Crossing over was allowed, but primary outcome analysis was based on the initial treatment modality assignment. Posttreatment care was standardized for both groups. Patient outcomes at 1 year were independently assessed using the modified Rankin Scale (mRS). A poor outcome was defined as an mRS score > 2 at 1 year. The primary outcome was based on the assigned group; that is, by intent to treat.

Results. One year after treatment, 403 patients were available for evaluation. Of these, 358 patients had actually undergone treatment. The remainder either died before treatment or had no identifiable source of SAH. A poor outcome (mRS score > 2) was observed in 33.7% of the patients assigned to aneurysm clipping and in 23.2% of the patients assigned to coil embolization (OR 1.68, 95% CI 1.08–2.61; p = 0.02). Of treated patients assigned to the coil group, 124 (62.3%) of the 199 who were eligible for any treatment actually received endovascular coil embolization. Patients who crossed over from coil to clip treatment fared worse than patients assigned to coil embolization, but no worse than patients assigned to clip occlusion. No patient treated by coil embolization suffered a recurrent hemorrhage.

Conclusions. One year after treatment, a policy of intent to treat favoring coil embolization resulted in fewer poor outcomes than clip occlusion. Although most aneurysms assigned to the coil treatment group were treated by coil embolization, a substantial number crossed over to surgical clipping. Although a policy of intent to treat favoring coil embolization resulted in fewer poor outcomes at 1 year, it remains important that high-quality surgical clipping be available as an alternative treatment modality.

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Thoracoscopic Resection of Symptomatic Herniated Thoracic Discs

Spine 2012 ; 37 : 35 – 40

Study Design. Retrospective review of a prospectively maintained surgical database.

Objective. To report the indications, surgical procedures performed, and outcomes from the largest series of thoracoscopically treated herniated thoracic discs (HTDs). We also compared approach-related complications with an unmatched cohort undergoing thoracotomy for HTD.

Summary of Background Data. Symptomatic HTDs are rare, and their surgical management is technically challenging.

Methods. A prospectively maintained surgical database of all patients undergoing surgery for symptomatic HTDs by the senior author (blinded for review) was reviewed. As needed, the database was supplemented with hospital and clinic charts and telephone conversations with patients. A triportal method of thoracoscopic discectomy was performed in all cases.

Results. Between 1994 and 2008, 121 patients underwent 125 thoracoscopic-assisted operations for 139 HTDs. Their mean age at surgery was 46.6 years. Indications for thoracoscopic resection currently include small symptomatic disc, anterior location, nonmorbidly obese patient, favorable chest anatomy, and T4–T11 location. Symptom duration averaged 32 months. Radiculopathy was the most common presentation, followed by myelopathy and pain (radiculopathic or back). The mean hospital stay was 4.8 days. Chest tubes remained in place for a mean of 3.2 days. At a mean follow-up of 2.4 years, myelopathy, radiculopathy, and back pain had resolved or improved at a rate of 91.1%, 97.6%, and 86.5%,of cases, respectively. Most patients (97.4%) would be willing to undergo the operation again. The complication rate was acceptable. Patients undergoing thoracoscopic excision had less approachrelated morbidity than an unmatched cohort undergoing excision using thoracotomy.

Conclusion. Thoracoscopic-assisted microsurgical resection is a safe, effective, and minimally invasive method of treating symptomatic HTDs in appropriately selected patients. The symptoms of most patients improve or resolve with minimal morbidity.

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Supraorbital Endoscopic Approach to Colloid Cysts

Neurosurgery 69[ONS Suppl 2]:ons176–ons183, 2011 DOI: 10.1227/NEU.0b013e318219563c

Surgical approaches to colloid cysts of the third ventricle have evolved over time. In recent years, endoscopy has been recognized as an effective alternative to open surgery. The disadvantage of endoscopic treatment is the difficulty in controlling the adhesion of the cyst to the roof of the third ventricle and in obtaining complete removal of the cyst.

OBJECTIVE: To design and carry out a supraorbital approach to obtain a better viewing angle of the cyst and better control of the adhesion of the cyst to the roof of the third ventricle.

METHODS: From September 2005 to February 2008, we operated on 7 consecutive patients with colloid cysts in the third ventricle. All procedures were performed with the endoscopic supraorbital approach. The endoscopic procedure was performed with a rigid STORZ endoscope with 3 working channels. In 4 patients, the surgical supraorbital trajectory was planned with the help of a navigator.

RESULTS: The procedures lasted between 60 and 110 minutes, including the registration on the navigation system. Near-total removal of the cyst was achieved in 6 patients. All patients were discharged within 6 days.

CONCLUSION: Endoscopic treatment may be an effective and safe alternative to open surgical craniotomy. Our series shows that the endoscopic supraorbital endoscopic resection is a valuable approach to colloid cysts of the third ventricle.

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Microsurgical Management of Hypoglossal Schwannomas Over 3 Decades: A Modified Grading Scale to Guide Surgical Approach

Neurosurgery 69[ONS Suppl 2]:ons121–ons140, 2011. DOI: 10.1227/NEU.0b013e31822a547b

Schwannomas originating from the hypoglossal nerve are extremely rare. Microsurgical resection with the goal for cure has traditionally been associated with a high risk of postoperative deficits.

OBJECTIVE: To summarize our clinical experience using tailored cranial base approaches for these formidable lesions.

METHODS: The clinical records of 13 patients were retrospectively reviewed. In addition, all reported patients in the literature were reviewed. The extreme lateral infrajugular transcondylar-transtubercular exposure approach was used in all of our patients. Based on our experience and literature analysis, we propose the following modified grading scale to facilitate surgical planning: type A, intradural tumors; type B, dumbbell-shaped tumors; type C, extracranial tumors; and type D, peripheral tumors.

RESULTS: All 13 patients underwent total, near-total, or subtotal tumor resection. Eight patients were men, 5 were women (mean age, 41.7 years). Sural nerve graft reconstruction for the hypoglossal nerve was performed in 4 patients. Three of the 4 patients in whom nerve reconstruction was performed regained satisfactory movement of their tongue. In the review of the literature, the mean patient age was 45.8 years. Patients presented with tongue atrophy (91.6%), headache (60.9%), and dysphagia (31.8%). The tumors were categorized as type A in 31.7% of these patients, type B in 38.6%, type C in 6.2%, and type D in 23.4%.

CONCLUSION: The extreme lateral infrajugular transcondylar-transtubercular exposure approach, which is a modification of the extreme lateral suboccipital approach, provides sufficient exposure for most intracranial dumbbell-shaped hypoglossal schwannomas. Hypoglossal nerve reconstruction using a sural nerve graft improves tongue atrophy and movement for patients with resected nerves.

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Accuracy of Image-Guided Pedicle Screw Placement Using Intraoperative Computed Tomography- Based Navigation With Automated Referencing. Part II: Thoracolumbar Spine

Neurosurgery 69:1307–1316, 2011 DOI: 10.1227/NEU.0b013e31822ba190

Image-guided spinal instrumentation may reduce complications in spinal instrumentation.

OBJECTIVE: To assess accuracy, time efficiency, and staff radiation exposure during thoracolumbar screw instrumentation guided by intraoperative computed tomography (iCT)-based neuronavigation (iCT-N).

METHODS: In 55 patients treated for idiopathic and degenerative deformities, 826 screws were inserted in the thoracic (T2–T12; n = 243) and lumbosacral (L1–S1; n = 545) spine, as well as ilium (n = 38) guided by iCT-N. Up to 17 segments were instrumented following a single automated registration sequence with the dynamic reference arc (DRA) uniformly attached to L5. Accuracy of iCT-N was assessed by calculating angular deviations between individual navigated tool trajectories and final implant positions. Final screw positions were also graded according to established classification systems. Clinical and radiological outcome was assessed at 12 to 14 months.

RESULTS: Additional intraoperative fluoroscopy was unnecessary, eliminating staff radiation exposure. Unisegmental K-wire insertion required 4.6 6 2.9 minutes. Of the thoracic pedicle screws 98.4% were assigned grades I to III according to the Heary classification, with 1.6% grade IV placement. In the lumbar spine, 94.4% of screws were completely contained (Gertzbein classification grade 0), 4.6% displayed minor pedicle breaches ,2 mm(grade 1), and 1% of lumbar screws deviated by.2 to,4 mm (grade 2). The accuracy of iCT-N progressively deteriorates with increasing distance from the DRA, but allows safe instrumentation of up to 12 segments.

CONCLUSION: iCT-N using automated referencing allows for safe, highly accurate multilevel instrumentation of the entire thoracolumbosacral spine and ilium, rendering additional intraoperative imaging dispensable. In addition, automated registration is time-efficient and significantly reduces the need for re-registration in multilevel surgery.

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Tumor origin and hearing preservation in vestibular schwannoma surgery

J Neurosurg 115:900–905, 2011. DOI: 10.3171/2011.7.JNS102092

Preservation of cochlear nerve function in vestibular schwannoma (VS) removal is usually dependent on tumor size and preoperative hearing status. Tumor origin as an independent factor has not been systematically investigated.

Methods. A series of 90 patients with VSs, who underwent surgery via a suboccipitolateral route, was evaluated with respect to cochlear nerve function, tumor size, radiological findings, and intraoperatively confirmed tumor origin. All patients were reevaluated 12 months after surgery.

Results. Despite comparable preoperative cochlear nerve status and larger tumor sizes, hearing preservation was achieved in 42% of patients with tumor originating from the superior vestibular nerve, compared with 16% of those with tumor originating from the inferior vestibular nerve.

Conclusions. Tumor origin is an important prognostic factor for cochlear nerve preservation in VS surgery.

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Enhanced analysis of intracerebral arteriovenous malformations by the intraoperative use of analytical indocyanine green videoangiography: technical note

Acta Neurochir (2011) 153:2181–2187. DOI 10.1007/s00701-011-1141-z

In cerebral arteriovenous malformations (AVMs) detailed intraoperative identification of feeding arteries, nidal vessels and draining veins is crucial for surgery.

Intraoperative imaging techniques like indocyanine green videoangiography (ICG-VAG) provide information about vessel architecture and patency, but do not allow time-dependent analysis of intravascular blood flow.

Here we report on our first experiences with analytical indocyanine green videoangiography (aICG-VAG) using FLOW 800 software as a useful tool for assessing the time-dependent intraoperative blood flow during surgical removal of cerebral AVMs. Microscope-integrated colour-encoded aICG-VAG was used for the surgical treatment of a 38-year-old woman diagnosed with an incidental AVM, Spetzler Martin grade I, of the left frontal lobe and of a 26-year-old man suffering from seizures caused by a symptomatic AVM, Spetzler Martin grade III, of the right temporal lobe. Analytical ICG-VAG visualization was intraoperatively correlated with in situ micro-Doppler investigation, as well as preoperative and postoperative digital subtraction angiography (DSA).

Analytical ICG-VAG is fast, easy to handle and integrates intuitively into surgical procedures. It allows colour-encoded visualization of blood flow distribution with high temporal and spatial resolution. Superficial major and minor feeding arteries can be clearly separated from the nidus and draining veins. Effects of stepwise vessel obliteration on velocity and direction of AVM blood flow can be objectified. High quality of visualization, however, is limited to the site of surgery. Colour-encoded aICG-VAG with FLOW 800 enables intraoperative real-time analysis of arterial and venous vessel architecture and might, therefore, increase efficacy and safety of neurovascular surgery in a selected subset of superficial AVMs.

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Exclusively intradural exposure and clip reconstruction in complex paraclinoid aneurysms

Acta Neurochir (2011) 153:2103–2109. DOI 10.1007/s00701-011-1171-6

The management of complex paraclinoid aneurysms is still challenging. In this article we describe our approach to paraclinoid aneurysms, which has evolved over several years, using an exclusively intradural approach.

Method All procedures are done under continuous electrophysiological monitoring. A standard pterional approach is used to access the paraclinoid region exclusively intraduraly. After optic nerve unroofing and tailored clinoidectomy, the aneurysm neck is visualized and clipped using the tandem clipping technique and suction decompression if necessary. Aneurysm occlusion is verified using intraoperative ICG angiography and postoperative 3D DSA.

Conclusion The exclusively intradural approach to complex paraclinoid aneurysms with tailored clinoidectomy offers an excellent surgical corridor for the treatment of these challenging lesions

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