Neurosurgery Blog

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

Journal of Neurosurgery: Spine DOI: 10.3171/2011.3.SPINE10445.

The accurate intraoperative localization of the correct thoracic spine level remains a challenging problem in both open and minimally invasive spine surgery. The authors describe a technique of using preoperatively placed percutaneous fiducial screws to localize the area of interest in the thoracic spine, and they assess the safety and efficacy of the technique.

METHODS

To avoid wrong-level surgery in the thoracic spine, the authors preoperatively placed a percutaneous 5-mm fiducial screw at the level of intended surgery using CT guidance. Plain radiographs and CT images with reconstructed views can then be referenced in the operating room to verify the surgical level, and the fiducial screw is easily identified on intraoperative fluoroscopy. The authors compared a group of 26 patients who underwent preoperative (often outpatient) fiducial screw placement prior to open or minimally invasive thoracic spine surgery to a historical group of 26 patients who had intraoperative localization with fluoroscopy alone.

RESULTS

In the treatment group of 26 patients, no complications related to fiducial screw placement occurred, and there was no incidence of wrong-level surgery. In comparison, there were no wrong-level surgeries in the historical cohort of 26 patients who underwent mini-open or open thoracic spine surgery without placement of a fiducial screw. However, the authors found that the intraoperative localization fluoroscopy time was greatly reduced when a fiducial screw localization technique was employed.

CONCLUSIONS

The aforementioned technique for intraoperative localization is safe, efficient, and accurate for identifying the target level in thoracic spine exposures. The fiducial marker screw can be placed using CT guidance on an outpatient basis. There is a reduction in the amount of intraoperative fluoroscopy time needed for localization in the fiducial screw group.

J Neurosurg 115:875–884, 2011. DOI: 10.3171/2011.6.JNS101958

In large vestibular schwannoma (VS), microsurgery is the main treatment option, and complete resection is considered the primary goal. However, previous studies have documented suboptimal facial nerve outcomes in patients who undergo complete resection of large VSs. Subtotal resection is likely to reduce the risk of facial nerve injury but increases the risk of lesion regrowth. Gamma Knife surgery (GKS) can be performed to achieve long-term growth control of residual VS after incomplete resection. In this study the authors report on the results in patients treated using planned subtotal resection followed by GKS with special attention to volumetric growth, control rate, and symptoms.

Methods. Fifty consecutive patients who underwent the combined treatment strategy of subtotal microsurgical removal and GKS for large VSs between 2002 and 2009 were retrospectively analyzed. Patients with neurofibromatosis Type 2 were excluded. Patient charts were reviewed for clinical symptoms. Audiograms were evaluated to classify hearing pre- and postoperatively. Preoperative and follow-up contrast-enhanced T1-weighted MR images were analyzed using volume-measuring software.

Results. Surgery was performed via a translabyrinthine (25 patients) or retrosigmoid (25 patients) approach. The median follow-up was 33.8 months. Clinical control was achieved in 92% of the cases and radiological control in 90%. One year after radiosurgery, facial nerve function was good (House-Brackmann Grade I or II) in 94% of the patients. One of the two patients who underwent surgery to preserve hearing maintained serviceable hearing after resection followed by GKS.

Conclusions. Considering the good tumor growth control and facial nerve function preservation as well as the possibility of preserving serviceable hearing and the low number of complications, subtotal resection followed by GKS can be the treatment option of choice for large VSs.

Neurosurgery 69:1046–1057, 2011 DOI: 10.1227/NEU.0b013e3182287bb9

Nonvestibular schwannomas of the skull base often represent a challenge owing to their anatomic location. With improved techniques in endoscopic endonasal skull base surgery, resection of various ventral skull base tumors, including schwannomas, has become possible.

OBJECTIVE: To assess the outcomes of using endoscopic endonasal approach (EEA) for nonvestibular schwannomas of the skull base.

METHODS: Seventeen patients operated on for skull base schwannomas by EEA at the University of Pittsburgh Medical Center from 2003 to 2009 were reviewed.

RESULTS: Three patients underwent combined approaches with retromastoid craniectomy (n = 2) and orbitopterional craniotomy (n = 1). Three patients underwent multistage EEA. The rest received a single EEA operation. Data on degree of resection were found for 15 patients. Gross total resection (n = 9) and near-total (.90%) resection (n = 3) were achieved in 12 patients (80%). There were no tumor recurrences or postoperative cerebrospinal fluid leaks. In 3 of 7 patients with preoperative sensory deficits of trigeminal nerve distribution, there were partial improvements. Patients with preoperative reduced vision (n = 1) and cranial nerve VI or III palsies (n = 3) also showed improvement. Five patients had new postoperative trigeminal nerve deficits: 2 had sensory deficits only, 1 had motor deficit only, and 2 had both motor and sensory deficits. Three of these patients had partial improvement, but 3 developed corneal neurotrophic keratopathy.

CONCLUSION: An EEA provides adequate access for nonvestibular schwannomas invading the skull base, allowing a high degree of resection with a low rate of complications.

Neurosurgical Focus Oct 2011 / Vol. 31 / No. 4 / Page E4

Recently, the minimally invasive, lateral retroperitoneal, transpsoas approach to the thoracolumbar spinal column has been described by various authors. This is known as the minimally invasive lateral lumbar interbody fusion. The purpose of this study is to elucidate the approach-related morbidity associated with the minimally invasive transpsoas approach to the lumbar spine. To date, there have been only a couple of reports regarding the morbidity of the transpsoas muscle approach.

METHODS

A nonrandomized, prospective study utilizing a self-reported patient questionnaire was conducted between January 2006 and June 2008 at Northwestern University. Data were collected in 53 patients with a follow-up period ranging from 6 months to 3.5 years. Only 2 patients were lost to follow-up.

RESULTS

Thirty-six percent (19 of 53) of patients reported subjective hip flexor weakness, 25% (13 of 53) anterior thigh numbness, and 23% (12 of 53) anterior thigh pain. However, 84% of the 19 patients reported complete resolution of their subjective hip flexor weakness by 6 months, and most experienced improved strength by 8 weeks. Of those reporting anterior thigh numbness and pain, 69% and 75% improved to their baseline function by the 6-month follow-up evaluations, respectively. All patients with self-reported subjective hip flexor weakness underwent examinations during subsequent clinic visits after surgery; however, these examinations did not confirm a motor deficit less than Grade 5. Subset analysis showed that the L3–4 and L4–5 levels were most often affected.

CONCLUSIONS

The minimally invasive, transpsoas muscle approach to the lumbar spine has a number of advantages. The data show that a percentage of the patients undergoing the transpsoas approach will have temporary sensory and motor symptoms related to this approach. The majority of the symptoms are thought to be related to psoas muscle inflammation and/or stretch injury to the genitofemoral nerve due to the surgical corridor traversed during the operation. No major injuries to the lumbar plexus were encountered. It is important to educate patients prior to surgery of the possibility of these largely transient symptoms.

Journal of Neurosurgery Oct 2011 / Vol. 115 / No. 4 / Pages 700-706

For oculomotor nerve palsy (ONP) induced by unruptured posterior communicating artery (PCoA) aneurysms, the authors performed surgical clipping via a superciliary keyhole approach as an optimal treatment modality with high efficiency and low invasiveness. In this study, they then evaluated the technical feasibility, safety, clinical outcomes, including recovery from ONP as well as cosmetic results, and durability of the procedure.

METHODS Thirteen patients presenting with complete (7 patients) or incomplete (6 patients) ONP underwent surgery via a superciliary approach. The operative video record was used to evaluate the technical feasibility, neurological examinations and CT were performed to analyze the safety of the treatment, and neuroophthalmological examinations and 3D CT angiography were undertaken to determine the effectiveness and durability of the treatment.

RESULTS In all cases, the aneurysms were successfully clipped using a 3.5-cm eyebrow incision and supraorbital minicraniotomy. The mean operative time was 108 ± 24 minutes. Twelve (92.3%) of the 13 patients showed complete resolution of the ONP. All 6 patients (100%) with incomplete ONP recovered completely within 1–2 months after surgery, whereas 6 (85.7%) of the 7 patients with complete ONP recovered completely within 1–6 months after surgery. Cosmetic results for the operative wounds were excellent without frontalis palsy. The durability of the treatment was ascertained based on 3D CT angiograms obtained 1 year after surgery.

CONCLUSIONS Surgical clipping via a superciliary keyhole approach can be an optimal treatment modality for PCoA aneurysms inducing ONP because it is effective, safe, and durable.

Eur Spine J (2011) 20:1684–1690. DOI 10.1007/s00586-011-1821-7
We present clinical findings, radiological characteristics and surgical modalities of various posterior approaches to thoracic disc herniations and report the clinical results in 27 consecutive patients. Within an 8-year period 27 consecutive patients (17 female, 10 male) aged 30–83 years (mean 53 years.) were surgically treated for 28 symptomatic herniated thoracic discs in our department. Six of these lesions (21%) were calcified. In all cases surgery was performed via individually tailored posterior approaches. We evaluated the pre- and postoperative clinical status and the complication rate in a retrospective study.
Nearly one half of the lesions (46.4%) were located at the three lowest thoracic segments. Clinical symptoms included back pain or radicular pain (77.8%), altered sensitivity (77.8%), weakness (40.7%), impaired gait (51.9%) or bladder dysfunction (22%). Costotransversectomy was performed in 8 patients, 1 lateral extracavitary approach, 2 foraminotomies, 15 transfacet and/or transpedicular approaches and 2 interlaminar approaches were used for removing the pathologies. After a mean follow-up of 38.6 months (3–100 months), complete normalization or reduction of local pain was recorded in 87%of the patients and of radicular pain in 70%of the cases, increased motor strength could be achieved in 55%, sensitivity improved in 76.2% and improvement of myelopathy was noted in 71.4%. Two patients suffered from postoperative impairment of sensory deficits, which in one case was discrete. The overall recovery rate within the modified JOA score was 39.5%. In 1 patient, two revisions were required because of instability and a persisting osteophyte, respectively. The rate of major complications was 7.1% (2/28).
Surgical treatment of thoracic disc herniations via posterior approaches tailored to the individual patient produces satisfying results referring to clinical outcome. Posterior approaches remain a viable alternative for a large proportion of patients with symptomatic thoracic disc herniations.