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Patient response to awake craniotomy

awake craniotomy

Acta Neurochir (2014) 156:1063–1070

Awake craniotomy is a valuable procedure since it allows brain mapping and live monitoring of eloquent brain functions. The advantage of minimizing resource utilization is also emphasized by some physicians in North America. Data on how well an awake craniotomy is tolerated by patients and how much stress it creates is available from different studies, but this topic has not consequently been summarized in a review of the available literature. Therefore, it is the purpose of this review to shed more light on the still controversially discussed aspect of an awake craniotomy.

Methods We reviewed the available English literature published until December 2013 searching for studies that investigated patients’ responses to awake craniotomies.

Results Twelve studies, published between 1998 and 2013, including 396 patients with awake surgery were identified. Eleven of these 12 studies set the focus on the perioperative time, one study focused on the later postoperative time. The vast majority of patients felt well prepared and overall satisfaction with the procedure was high. In the majority of studies up to 30 % of the patients recalled considerable pain and 10– 14 % experienced strong anxiety during the procedure. The majority of patients reported that they would undergo an awake craniotomy again. A post traumatic stress disorder was present neither shortly nor years after surgery. However, a normal human response to such an exceptional situation can for instance be the delayed appearance of unintentional distressing recollections of the event despite the patients’ satisfaction concerning the procedure.

Conclusions For selected patients, an awake craniotomy presents the best possible way to reduce the risk of surgery related neurological deficits. However, benefits and burdens of this type of procedure should be carefully considered when planning an awake craniotomy and the decision should serve the interests of the patient.

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Contrast-Enhanced Angiographic Computed Tomography for Detection of Aneurysm Remnants After Clipping

Aneurysm

Neurosurgery 74:606–614, 2014 

For preclusion of remnants after aneurysm clipping, a reliable, noninvasive imaging technique is desirable.

OBJECTIVE: To evaluate the reliability of optimized angiographic computed tomography with intravenous contrast agent injection (ivACT) in detecting remnants after aneurysmal clipping compared with digital subtraction angiography (DSA), the gold standard.

METHODS: We included 84 patients with 112 clipped cerebral aneurysms of the anterior circulation. For treatment, 116 clips of cobalt and 57 clips of titanium alloy were used. In each patient, we performed an ivACT with dual rotational acquisition and a DSA. Data from ivACT were postprocessed with a dual-volume technique with newly implemented reconstructions modes. Aneurysm remnants were measured, classified, and correlated with DSA by 2 raters.

RESULTS: In total, 12 remnants were revealed by DSA, meaning a prevalence of 11%. IvACT demonstrated a sensitivity of 75% to 92% and a specificity of 99% in detecting remnants up to a minimal size of 0.7 · 0.3 mm. Classification of remnants by ivACT was identical to that by DSA, and assessment of size showed a significant correlation with DSA (P , .001). No significant differences between cobalt and titanium alloy were revealed concerning artifacts.

CONCLUSION: Optimized ivACT with enhanced postprocessing demonstrated high sensitivity and specificity in detecting remnants after aneurysm clipping in the anterior circulation. Classification and assessment of remnant size and detection of relevant parent artery stenosis showed high accuracy of ivACT compared with DSA. Our results indicate that ivACT might become a noninvasive alternative to DSA for postsurgical control.

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Classification of the Superior Petrosal Veins and Sinus Based on Drainage Pattern

Classification of the Superior Petrosal Veins and Sinus Based on Drainage Pattern

Operative Neurosurgery 10:357–367, 2014

The increasing number of reports of complications after sacrificing the superior petrosal veins, the largest veins in the posterior fossa, has led to a need for an increased understanding of the anatomy of these veins and the superior petrosal sinus into which they empty.

OBJECTIVE: To examine the anatomy of the superior petrosal veins and their size, draining area, and tributaries, as well as the anatomic variations of the superior petrosal sinus.

METHOD: Injected cadaveric cerebellopontine angles and 3-dimensional multifusion angiography images were examined.

RESULTS: The 4 groups of the superior petrosal veins based on their tributaries, course, and draining areas are the petrosal, posterior mesencephalic, anterior pontomesencephalic, and tentorial groups. The largest group was the petrosal group. Its largest tributary, the vein of the cerebellopontine fissure, was usually identifiable in the suprafloccular cistern located above the flocculus on the lateral surface of the middle cerebellar peduncle. The medial or lateral segment of the superior petrosal sinus was absent in 40% of cerebellopontine angles studied with venography.

CONCLUSION: The superior petrosal veins and their largest tributaries, especially the vein of the cerebellopontine fissure, should be preserved if possible. Obliteration of superior petrosal sinuses in which either the lateral or medial portion is absent may result in loss of the drainage pathway of the superior petrosal veins. Preoperative assessment of the superior petrosal sinus should be considered before transpetrosal surgery in which the superior petrosal sinus may be obliterated.

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Should ventriculoatrial shunting be the procedure of choice for normal-pressure hydrocephalus?

hydrocephalus

J Neurosurg 120:1458–1464, 2014

Ventriculoatrial (VA) shunting is rarely used for patients with normal-pressure hydrocephalus (NPH), likely due to surgeon technical preference and case reports indicating cardiopulmonary complications. However, these complications have typically been limited to adults in whom VA shunts had been placed when they were children. Few studies have directly compared VA shunting to ventriculoperitoneal (VP) shunting in cases of NPH.

Methods. The authors retrospectively analyzed all NPH patients treated by a single surgeon at their center from January 2002 through December 2011. Thirty patients were treated with VA shunts (14 male) and 157 with VP shunts (86 male). The patients’ mean age (± SD) at surgery was 73.7 ± 9.4 years for VA shunting and 76.0 ± 8.2 years for VP shunting; the median durations of follow-up were 42.0 months (IQR 19.2–63.6 months) and 34.2 months (IQR 15.8–67.5), respectively. Statistical analysis was performed using chi-square tests and Wilcoxon rank-sum tests.

Results. Perioperative and postoperative complications for VA and VP shunting cohorts, respectively, included distal revision (2.7% vs 6.6%, p = 0.45), proximal revision (2.7% vs 2.5%, p = 0.97), and postoperative seizure (2.7% vs 1.5%, p = 0.62). Shunt drainage–related subdural hematomas/hygromas developed in 8.1%/27.0% of VA shunt– treated patients versus 6.6%/26.4% of VP shunt–treated patients (p = 0.76/0.98) and were nearly always successfully managed with programmable-valve adjustment. Symptomatic intracerebral hemorrhage (1.5%) and shunt infection (2.0%) were only observed in those who underwent VP shunting. Of note, no cardiovascular complications were observed in any patient, and there were no cases of distal occlusion of the VA shunt.

Conclusions. The authors found no significant differences in complication rates between VA and VP shunting, and VA shunting was not associated with any cardiopulmonary complications. Thus, in the authors’ experience, VA shunting is at least as safe as VP shunting for treating NPH. (http://thejns.org/doi/abs/10.3171/2014.1.JNS131808) Key Words • normal-pressure hydrocephalus • ventriculoatrial shunt • ventriculoperitoneal shunt

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Robot-Assisted Stereotactic Laser Ablation in Medically Intractable Epilepsy

Robot_Assisted_Stereotactic_Laser_Ablation_in

Operative Neurosurgery 10:167–173, 2014

Stereotactic laser ablation offers an advantage over open surgical procedures for treatment of epileptic foci, tumors, and other brain pathology. Robotassisted stereotactic laser ablation could offer an accurate, efficient, minimally invasive, and safe method for placement of an ablation catheter into the target.

OBJECTIVE: To determine the feasibility of placement of a stereotactic laser ablation catheter into a brain lesion with the use of robotic assistance, via a safe, accurate, efficient, and minimally invasive manner.

METHODS: A laser ablation catheter (Visualase, Inc) was placed by using robotic guidance (ROSA, Medtech Surgical, Inc) under general anesthesia into a localized epileptogenic periventricular heterotopic lesion in a 19-year-old woman with 10-year refractory focal seizure history. The laser applicator (1.65 mm diameter) position was confirmed by using magnetic resonance imaging (MRI). Ablation using the Visualase system was performed under multiplanar imaging with real-time thermal imaging and treatment estimates in each plane. A postablation MRI sequence (T1 postgadolinium contrast injection) was used to immediately confirm the ablation. RESULTS: MRI showed accurate skin entry point and trajectory, with the applicator advanced to the lesion’s distal boundary. Ablation was accomplished in less than 3 minutes of heating. The overall procedure, from time of skin incision to end of last ablation, was approximately 90 minutes. After confirmation of proper lesioning by using a T1 contrast-enhanced MRI, the applicator was removed, and the incision was closed using a single stitch. No hemorrhage or other untoward complication was visualized. The patient awoke without any complication, was observed overnight after admitting to a regular floor bed, and was discharged to home the following day.

CONCLUSION: This technique, using a combination of Visualase laser ablation, ROSA robot, and intraoperative MRI, facilitated a safe, efficacious, efficient, and minimally invasive approach that could be used for placement of 1 or multiple electrodes in the future.

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Operative management of trigeminal neuromas

trigeminal neuroma

Acta Neurochir (2014) 156:1105–1114

The trigeminal schwannoma is the second most common intracranial schwannoma. Their proximity to the critical skull base neural and vascular structures increases the complexity of surgical treatment. The aim of this study was to better understand the surgical approaches and the prognosis, as well as to assess the optimum therapeutic schedule.

Methods This was a retrospective study of 55 patients with trigeminal schwannomas who visited our department between Jan 2007 and Jan 2012. We analyzed the clinical and radiological presentation, tumor characteristics, surgical approaches, the prognosis.

Results The patients were 30 women and 25 men of mean age 36 years (range, 6–66 years) who received postoperative neurological and neuroradiological follow-up. The tumor was located in the middle fossa (type A) in 13 cases, in the posterior fossa (type B) in ten cases, in the middle and posterior fossae (type C) in 21 cases, and in the branches of the trigeminal nerve (type D) in 11 cases. The most common symptom was facial hypesthesia or numbness in 36 patients (65%) . Total and nearly total tumor resection was achieved in 51 cases (93 %). Three patients (5 %) had worsening of preexisting deficits and there was no perioperative mortality. With an average follow-up period of 35 months, facial hypesthesia persisted in 26 patients (72 %),and improved in ten patients (28 %). Facial pain was relieved in 11 patients (100 %). There has been a recurrence in one case (2%) and all patients resumed independent and social reintegration.

Conclusion This study demonstrates radical surgery with excellent neurological outcomes is the primary treatment of trigeminal schwannomas. Appropriate selection of surgical approach according to tumor types is highly important and necessary. The preoperative facial pain could be relieved, hypesthesia frequently remains or could even be worsened after surgery.

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Corridor-Based Endonasal Endoscopic Surgery for Pediatric Skull Base Pathology

CORRIDOR-BASED EEA IN PEDIATRIC PATIENTS

Operative Neurosurgery 10:273–293, 2014

Pediatric anatomy is more restricted, and the propagation of endonasal endoscopic approaches in the pediatric population has been limited.

OBJECTIVE: To demonstrate the feasibility of the endonasal endoscopic approach in a variety of age groups and to perform measurements of the corridors and spaces available for surgery as a guide for case selection.

METHODS: Only patients ,18 years were included. The choice of operative corridor/ approach is described in relation to pathological entity and location. Preoperative/ postoperative visual fields and endocrine panels, extent of resection, as well as postoperative long-term complications are described. Prospective magnetic resonance image-based anatomic measurements of key distances were performed to determine age-dependent surgical indications and limitations.

RESULTS: Forty purely endoscopic procedures were performed in 33 pediatric patients (5-18 years of age) harboring a variety of skull base lesions, from benign tumors to congenital malformations. For the 20 patients in whom gross total resection was the intended goal of surgery, gross total resection was attained in 15 (75%). There were 2 infections (5%) and no cerebrospinal fluid leaks. Significant improvement was shown in 58.3% of patients with visual deficits. Hormone overproduction resolved in 75% of patients, while preoperative hormone insufficiency only improved in 29.2%. Wider intercarotid distance at the superior clivus (P = .01) and shorter nare-dens working distance (P = .001) predicted improved outcomes and fewer postoperative complications.

CONCLUSION: Endonasal endoscopic skull base approaches are viable in the pediatric population, they are not impeded by sphenoid sinus aeration, and they have minimal risk of cerebrospinal fluid leak and meningitis. Outcomes and complications can be predicted based on specific radio anatomical skull base measurements rather than age.

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Anatomic Study of the Central Core of the Cerebrum Correlating 7-T Magnetic Resonance Imaging and Fiber Dissection With the Aid of a Neuronavigation System

Anatomic Study of the Central Core of the Cerebrum Correlating 7-T Magnetic Resonance Imaging and Fiber Dissection With the Aid of a Neuronavigation System

Neurosurgery 10:294–304, 2014

Different strategies have been used to study the fiber tract anatomy of the human brain in vivo and ex vivo. Nevertheless, the ideal method to study white matter anatomy has yet to be determined because it should integrate information obtained from multiple sources.

OBJECTIVE: We developed an anatomic method in cadaveric specimens to study the central core of the cerebrum combining traditional white matter dissection with highresolution 7-T magnetic resonance imaging (MRI) of the same specimen coregistered using a neuronavigation system.

METHODS: Ten cerebral hemispheres were prepared using the traditional Klingler technique. Before dissection, a structural ultrahigh magnetic field 7-T MRI study was performed on each hemisphere specifically prepared with surface fiducials for neuronavigation. The dissection was then performed from the medial hemispheric surface using the classic white fiber dissection technique. During each step of the dissection, the correlation between the anatomic findings and the 7-T MRI was evaluated with the neuronavigation system.

RESULTS: The anatomic study was divided in 2 stages: diencephalic and limbic. The diencephalic stage included epithalamic, thalamic, hypothalamic, and subthalamic components. The limbic stage consisted of extending the dissection to complete the Papez circuit. The detailed information given by the combination of both methods allowed us to identify and validate the position of fibers that may be difficult to appreciate and dissect (ie, the medial forebrain bundle).

CONCLUSION: The correlation of high-definition 7-T MRI and the white matter dissection technique with neuronavigation significantly improves the understanding of the structural connections in complex areas of the human cerebrum.

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The behavior of residual tumors and facial nerve outcomes after incomplete excision of vestibular schwannomas

 incomplete excision of vestibular schwannomas

J Neurosurg 120:1278–1287, 2014

The authors evaluated the behavior of residual tumors and facial nerve outcomes after incomplete excision of vestibular schwannomas (VSs).

Methods. The case records of all patients who underwent surgical treatment of VSs were analyzed. All patients in whom an incomplete excision had been performed were analyzed. Incomplete excision was defined as near-total resection (NTR), subtotal resection (STR), and partial resection (PR). Tumors in the NTR and STR categories were followed up with a wait-and-rescan approach, whereas the tumors in the PR category were subjected to a second- stage surgery and were excluded from this series. All patients included in the study underwent baseline MRI at the 3rd and 12th postoperative months, and repeat imaging was subsequently performed every year for 7–10 years postoperatively or as indicated clinically. Preoperative and postoperative facial function was noted.

Results. Of the 2368 patients who underwent surgery for VS, 111 patients who had incomplete excisions of VSs were included in the study. Of these patients, 73 (65.77%) had undergone NTR and 38 (34.23%) had undergone STR. Of the VSs, 62 (55.86%) were cystic and 44 (70.97%) of these cystic VSs underwent NTR. The residual tumor was left behind on the facial nerve alone in 62 patients (55.86%), on the facial nerve and vessels in 2 patients (1.80%), on the facial nerve and brainstem in 15 patients (13.51%), and on the brainstem alone in 25 patients (22.52%). In the 105 patients with normal preoperative facial nerve function, postoperative facial nerve function was House-Brackmann (HB) Grades I and II in 51 patients (48.57%), HB Grade III in 34 patients (32.38%), and HB Grades IV–VI in 20 pa- tients (19.05%). Seven patients (6.3%) showed evidence of tumor regrowth on follow-up MRI. All 7 patients (100%) who showed evidence of tumor regrowth had undergone STR. No patient in the NTR group exhibited regrowth. The Kaplan-Meier plot demonstrated a 5-year tumor regrowth-free survival of 92%, with a mean disease-free interval of 140 months (95% CI 127–151 months). The follow-up period ranged from 12 to 156 months (mean 45.4 months).

Conclusions. The authors’ report and review of the literature show that there is undoubtedly merit for NTR and STR for preservation of the facial nerve. On the basis of this they propose an algorithm for the management of incomplete VS excisions. Patients who undergo incomplete excisions must be subjected to follow-up MRI for a period of at least 7–10 years. When compared with STR, NTR via an enlarged translabyrinthine approach has shown to have a lower rate of regrowth of residual tumor, while having almost the same result in terms of facial nerve function.

 

 

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Use of intraoperative fluorescein sodium fluorescence to improve the accuracy of tissue diagnosis during stereotactic needle biopsy of high-grade gliomas

stereotactic biopsy specimen obtained under the YELLOW560

Acta Neurochir (2014) 156:1071–1075

Stereotactic needle biopsy is valuable for tissue diagnosis of suspected high-grade gliomas, but limited by a sampling error that can lead to inappropriate grading of the tumor or failure to provide diagnosis. Increasing the number of biopsy attempts can increase morbidity. The authors designed a protocol to increase safety and efficiency of the procedure.

Methods Six consecutive patients with suspected high-grade gliomas who were not candidates for cytoreductive surgery underwent fluorescein-guided stereotactic needle biopsy. All received an injection of 3 mg/kg fluorescein sodium during anesthesia induction. Samples were obtained and observed under a microscope-integrated fluorescent module. If the initial specimens were fluorescent, the procedure was complete if the pathologist confirmed diagnostic tissue. Additional specimens were obtained only at the pathologist’s request. An independent neuropathologist later analyzed and graded samples for diagnostic value, tumor, and necrosis. This information was correlated to the degree of intraoperative fluorescent signal in biopsy samples.

Results During six biopsy procedures, 26 specimens were obtained: 15 (58 %) fluorescent and 11 (42%) nonfluorescent. All fluorescent specimens contained diagnostic tissue appropriate for tumor grading. Of 11 nonfluorescent specimens, four (36 %) did not contain tumor, three (27 %) contained minor hypercellularity or gliosis, and four (36 %) contained tumor with a high proportion of necrosis. All six tumors were diagnosed as glioblastoma multiforme. The sensitivity and specificity for fluorescein fluorescence was 79 % and 100 %, respectively.

Conclusions Fluorescein fluorescence may improve diagnostic accuracy and expedite stereotactic biopsy procedures.

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An Optimized 3-T Magnetic Resonance Imaging Sequence for Targeting the Subthalamic Nucleus

High-Resolution 3-Dimensional T2*-Weighted Angiography (HR 3-D SWAN)- An Optimized 3-T Magnetic Resonance Imaging Sequence for Targeting the Subthalamic Nucleus

Neurosurgery 74:615–627, 2014

Subthalamic nucleus deep brain stimulation (STN-DBS) is an established treatment for Parkinson’s disease.

OBJECTIVE: To characterize an optimized magnetic resonance imaging (MRI) sequence (high-resolution 3-dimensional T2*-weighted angiography [HR 3-D SWAN]) for direct STN targeting.

METHODS: Sequence distortions were measured using the Leksell stereotactic phantom. Eight consecutive candidates for STN-DBS underwent HR 3-D SWAN MRI for direct identification of the 16 STN. Two senior neurosurgeons independently determined the boundaries of STN on a semiquantitative scale (ranging from 1 [identification very easy] to 4 [identification very difficult]) and the anatomic target within the nucleus. The anatomic data were compared with electrophysiological recordings (48 microrecordings). We examined the anatomic location of the active contacts on MRI.

RESULTS: The mean distortion error over the phantom was 0.16 mm. For the 16 STNs, identification of the upper, internal, anterior, and external edges was considered to be easy (scores of 1 or 2). The distinction between the substantia nigra and the STN was rated 1 or 2 for all but 6 nuclei. In the mediolateral axis, electrophysiological recordings covered perfectly anatomic data. In the craniocaudal axis, the mean differences between the electrophysiological data and the anatomic data were 0.8 mm and 0.19 mm for the “entry” and “exit” of the STN, respectively. All active contacts were located within the STN on MRI.

CONCLUSION: HR 3-D SWAN allows easy visualization of the STN. Adapted to stereotactic requirement, the sequence simplifies direct targeting in STN-DBS surgery.

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Surgery in lumbar degenerative spondylolisthesis: indications, outcomes and complications. A systematic review

Lumbar spondylolisthesis

Eur Spine J (2014) 23:945–973

This systematic review summarises the literature on patient selection, decision-making, effectiveness and outcomes in the surgical treatment of lumbar degenerative spondylolisthesis (LDS). Introduction In daily practice, decision-making in the treatment of LDS is challenging. There is little consensus on either the precise indications or prognostic factors for any specific therapy (operative or non-operative).

Methods We searched for LDS trials published between 01.01.1990 and 16.11.2011 in Medline, Embase, Cochrane Library and Cinahl. Two independent reviewers selected studies according to the inclusion criteria. Data were then extracted by two of the authors. Quality assessment was performed using the Downs and Black list for the clinical trials/studies and AMSTAR for the reviews. Results Data synthesis: 21 papers met the inclusion criteria (2 studies comprising both a RCT and a concurrent observational analysis, 1 RCT, 6 prospective studies, 8 retrospective studies, 3 reviews, 1 review guideline). The quality of the clinical studies was on average ‘‘fair’’ [mean score 15.6 points (range 10–19) out of 24 points (Downs and Black)]. The quality of the reviews ranged from 1 to 7 out of 11 points with an average of 5 points (AMSTAR). The study outcomes could not be subject to meta-analysis due to heterogeneity of study design and variable measure used.

Conclusions Despite there being many articles describing and/or comparing different surgical options for LDS, there was insufficient evidence to draw conclusions concerning clear indications for specific types of surgical treatment, predictors of outcome or complication rates. There remains a need to establish a decision-making tool to facilitate daily clinical practice and to assure appropriate treatment for patients with LDS.

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Novel embalming solution for neurosurgical simulation in cadavers

Novel embalming solution for surgical simulation

J Neurosurg 120:1229–1237, 2014

Surgical simulation using postmortem human heads is one of the most valid strategies for neurosurgical research and training. The authors customized an embalming formula that provides an optimal retraction profile and lifelike physical properties while preventing microorganism growth and brain decay for neurosurgical simulations in cadavers. They studied the properties of the customized formula and compared its use with the standard postmortem processing techniques: cryopreservation and formaldehyde-based embalming.

Methods. Eighteen specimens were prepared for neurosurgical simulation: 6 formaldehyde embalmed, 6 cryopreserved, and 6 custom embalmed. The customized formula is a mixture of ethanol 62.4%, glycerol 17%, phenol 10.2%, formaldehyde 2.3%, and water 8.1%. After a standard pterional craniotomy, retraction profiles and brain stiffness were studied using an intracranial pressure transducer and monitor. Preservation time—that is, time that tissue remained in optimal condition—between specimen groups was also compared through periodical reports during a 48-hour simulation.

Results. The mean (± standard deviation) retraction pressures were highest in the formaldehyde group and lowest in the cryopreserved group. The customized formula provided a mean retraction pressure almost 3 times lower than formaldehyde (36 ± 3 vs 103 ± 14 mm Hg, p < 0.01) and very similar to cryopreservation (24 ± 6 mm Hg, p < 0.01). For research purposes, preservation time in the cryopreserved group was limited to 4 hours and was unlimited for the customized and formaldehyde groups for the duration of the experiment.

Conclusions. The customized embalming solution described herein is optimal for allowing retraction and surgical maneuverability while preventing decay. The authors were able to significantly lower the formaldehyde content as compared with that in standard formulas. The custom embalming solution has the benefits from both cryopreservation (for example, biological brain tissue properties) and formaldehyde embalming (for example, preservation time and microorganism growth prevention) and minimizes their drawbacks, that is, rapid decay in the former and stiffness in the latter. The presented embalming formula provides an important advance for neurosurgical simulations in research and teaching.

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Treatment of Blister-Like Aneurysms With the Pipeline Embolization Device

Treatment of Blister-Like Aneurysms With the Pipeline Embolization Device

Neurosurgery 74:527–532, 2014

Endovascular vessel reconstruction with the pipeline embolization device (PED) has become common practice. Data on the safety and efficacy of the PED in blister-like aneurysms (BLAs) are limited.

OBJECTIVE: To retrospectively present our experience with use of the PED in BLAs.

METHODS: A total of 8 patients harboring 8 BLAs were treated with the PED at our institution between November 2011 and April 2013.

RESULTS: Aneurysm size was 2.5 mm on average. Five patients had sustained a subarachnoid hemorrhage (SAH), 1 patient presented with sentinel headaches, and in 2 patients the aneurysm was incidentally discovered. Seven aneurysms arose from the ICA and 1 from the basilar artery. Placement of the PED was successful in all 8 patients. There were no procedural or perioperative complications in any of the patients. At the latest follow-up, all 8 patients achieved a favorable outcome (mRS 0-2). Angiographic follow-up was available for 6 patients at a mean time point of 3.9 months. Follow-up angiography showed 100% aneurysm occlusion in 5 patients and marked decrease in aneurysm size in 1 patient.

CONCLUSION: The findings of this study suggest that the PED may be a safe and effective treatment for BLAs. Given the limitations of other treatment modalities and the challenging nature of BLAs, flow diversion may be a valuable option for these lesions.

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Multitarget, dual-electrode stimulation for Holmes’ tremor

Multitarget, dual-electrode stimulation for Holmes’ tremor

J Neurosurg 120:1025–1032, 2014

Holmes’ tremor (HT) is generally considered to be a symptomatic tremor associated with lesions of the cerebellum, midbrain, or thalamus. Deep brain stimulation (DBS) therapy for essential tremor and parkinsonian tremor has proved quite successful. In contrast, surgical treatment outcomes for HT have often been disappointing. The use of 2 ipsilateral DBS electrodes implanted in parallel within the thalamus for severe essential tremor has been reported. Since dual-lead stimulation within a single target can cover a wider area than single-lead stimulation, it produces greater effects. On the other hand, DBS of the subthalamic area (SA) was recently reported to be effective for refractory tremor.

Methods. The authors implanted 2 DBS electrodes (one at the nucleus ventralis oralis/nucleus ventralis intermedius and the other at the SA) in 4 patients with HT. For more than 2 years after implantation, each patient’s tremor was evaluated using a tremor rating scale under the following 4 conditions of stimulation: “on” for both thalamus and SA DBS; “off” for both thalamus and SA DBS; “on” for thalamus and “off” for SA DBS; and “on” for SA and “off” for thalamus DBS.

Results. The tremor in all patients was improved for more than 2 years (mean 25.8 ± 3.5 months). Stimulation with 2 electrodes exerted greater effect on the tremor than did 1-electrode stimulation. Interestingly, in all patients progressive effects were observed, and in one patient treated with DBS for 1 year, tremor did not appear even while stimulation was temporarily switched off, suggesting irreversible improvement effects. The presence of both resting and intentional/action tremor implies combined destruction of the pallidothalamic and cerebellothalamic pathways in HT. A larger stimulation area may thus be required for HT patients. Multitarget, dual-lead stimulation permits coverage of the wide area needed to suppress the tremor without adverse effects of stimulation. Some reorganization of the neural network may be involved in the development of HT because the tremor appears several months after the primary insult. The mechanism underlying the absence of tremor while stimulation was temporarily off remains unclear, but the DBS may have normalized the abnormal neural network.

Conclusions. The authors successfully treated patients with severe HT by using dual-electrode DBS over a long period. Such DBS may offer an effective and safe treatment modality for intractable HT.

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Minimally invasive spine surgery for adult degenerative lumbar scoliosis

Minimally invasive spine surgery for adult degenerative lumbar scoliosis

Neurosurg Focus 36 (5):E7, 2014

Historically, adult degenerative lumbar scoliosis (DLS) has been treated with multilevel decompression and instrumented fusion to reduce neural compression and stabilize the spinal column. However, due to the profound morbidity associated with complex multilevel surgery, particularly in elderly patients and those with multiple medical comorbidities, minimally invasive surgical approaches have been proposed. The goal of this meta-analysis was to review the differences in patient selection for minimally invasive surgical versus open surgical procedures for adult DLS, and to compare the postoperative outcomes following minimally invasive surgery (MIS) and open surgery.

Methods. In this meta-analysis the authors analyzed the complication rates and the clinical outcomes for patients with adult DLS undergoing complex decompressive procedures with fusion versus minimally invasive surgical approaches. Minimally invasive surgical approaches included decompressive laminectomy, microscopic decompression, lateral and extreme lateral interbody fusion (XLIF), and percutaneous pedicle screw placement for fusion. Mean patient age, complication rates, reoperation rates, Cobb angle, and measures of sagittal balance were investigated and compared between groups.

Results. Twelve studies were identified for comparison in the MIS group, with 8 studies describing the lateral interbody fusion or XLIF and 4 studies describing decompression without fusion. In the decompression MIS group, the mean preoperative Cobb angle was 16.7° and mean postoperative Cobb angle was 18°. In the XLIF group, mean pre- and postoperative Cobb angles were 22.3° and 9.2°, respectively. The difference in postoperative Cobb angle was statistically significant between groups on 1-way ANOVA (p = 0.014). Mean preoperative Cobb angle, mean patient age, and complication rate did not differ between the XLIF and decompression groups. Thirty-five studies were identified for inclusion in the open surgery group, with 18 studies describing patients with open fusion without osteotomy and 17 papers detailing outcomes after open fusion with osteotomy. Mean preoperative curve in the open fusion without osteotomy and with osteotomy groups was 41.3° and 32°, respectively. Mean reoperation rate was significantly higher in the osteotomy group (p = 0.008). On 1-way ANOVA comparing all groups, there was a statistically significant difference in mean age (p = 0.004) and mean preoperative curve (p = 0.002). There was no statistically significant difference in complication rates between groups (p = 0.28).

Conclusions. The results of this study suggest that surgeons are offering patients open surgery or MIS depending on their age and the severity of their deformity. Greater sagittal and coronal correction was noted in the XLIF versus decompression only MIS groups. Larger Cobb angles, greater sagittal imbalance, and higher reoperation rates were found in studies reporting the use of open fusion with osteotomy. Although complication rates did not significantly differ between groups, these data are difficult to interpret given the heterogeneity in reporting complications between studies.

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Medial acoustic neuromas: clinical and surgical implications

Medial VIII schwannoma

J Neurosurg 120:1095–1104, 2014

Medial acoustic neuroma is a rare entity that confers a distinct clinical syndrome. It is scarcely discussed in the literature and is associated with adverse features. This study evaluates the clinical and imaging features, pertinent surgical challenges, and treatment outcome in a large series of this variant. The authors postulate that the particular pathological anatomy with its arachnoidal rearrangement has a profound implication on the surgical technique and outcome.

Methods. The authors conducted a retrospective analysis of 52 cases involving 33 women and 19 men who underwent resection of medial acoustic neuromas performed by the senior author (O.A.) over a 20-year period (1993– 2013). Clinical, radiological, and operative records were reviewed, with a specific focus on the neurological outcomes and facial nerve function and hearing preservation. Intraoperative findings were analyzed with respect to the effect of arachnoidal arrangement on the surgeon’s ability to resect the lesion and the impact on postoperative function.

Results. The average tumor size was 34.5 mm (maximum diameter), with over 90% of tumors being 25 mm or larger and 71% being cystic. Cerebellar, trigeminal nerve, and facial nerve dysfunction were common preoperative findings. Hydrocephalus was present in 11 patients. Distinguishing intraoperative findings included marked tumor adherence to the brainstem and frequent hypervascularity, which prompted intracapsular dissection resulting in enhancement on postoperative MRI in 18 cases, with only 3 demonstrating growth on follow-up. There was no mortality or major postoperative neurological deficit. Cerebrospinal fluid leak was encountered in 7 patients, with 4 requiring surgical repair. Among 45 patients who had intact preoperative facial function, only 1 had permanent facial nerve paralysis on extended follow-up. Of the patients with preoperative Grade I–II facial function, 87% continued to have Grade I–II function on follow-up. Of 10 patients who had Class A hearing preoperatively, 5 continued to have Class A or B hearing after surgery.

Conclusions. Medial acoustic neuromas represent a rare subgroup whose site of origin and growth patterns produce a distinct clinical presentation and present specific operative challenges. They reach giant size and are frequently cystic and hypervascular. Their origin and growth pattern lead to arachnoidal rearrangement with marked adherence against the brainstem, which is critical in the surgical management. Excellent surgical outcome is achievable with a high rate of facial nerve function and attainable hearing preservation. These results suggest that similar or better results may be achieved in less complex tumors.

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Occipital artery to posterior inferior cerebellar artery bypass

How I do it- occipital artery to posterior inferior cerebellar artery bypass

Acta Neurochir (2014) 156:971–975

Aneurysms located at the proximal posterior inferior cerebellar artery (PICA) may need to be addressed by trapping and concomitant bypass. An anastomosis of the Occipital Artery (OA) to PICA is one bypass option in these cases. This bypass is highly challenging and its technical description is seldom cited in the literature.

Methods We describe the technical nuances of an OA-PICA end-to-side bypass in a 63-year-old man with a dissecting ruptured aneurysm of the third segment (tonsilomedullary) of the PICA.

Conclusion OA-PICA bypass option should remain as a treatment modality in the armamentarium of neurovascular surgeons.

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Trigeminal neuralgia occurs and recurs in the absence of neurovascular compression

NVC-TN

J Neurosurg 120:1048–1054, 2014

Vascular compression of the trigeminal nerve is the most common factor associated with the etiology of trigeminal neuralgia (TN). Microvascular decompression (MVD) has proven to be the most successful and durable surgical approach for this disorder. However, not all patients with TN manifest unequivocal neurovascular compression (NVC). Furthermore, over time patients with an initially successful MVD manifest a relentless rate of TN recurrence.

Methods. The authors performed a retrospective review of cases of TN Type 1 (TN1) or Type 2 (TN2) involving patients 18 years or older who underwent evaluation (and surgery when indicated) at Oregon Health & Science University between July 2006 and February 2013. Surgical and imaging findings were correlated.

Results. The review identified a total of 257 patients with TN (219 with TN1 and 38 with TN2) who underwent high-resolution MRI and MR angiography with 3D reconstruction of combined images using OsiriX. Imaging data revealed that the occurrence of TN1 and TN2 without NVC was 28.8% and 18.4%, respectively. A subgroup of 184 patients underwent surgical exploration. Imaging findings were highly correlated with surgical findings, with a sensitivity of 96% for TN1 and TN2 and a specificity of 90% for TN1 and 66% for TN2.

Conclusions. Magnetic resonance imaging detects NVC with a high degree of sensitivity. However, despite a diagnosis of TN1 or TN2, a significant number of patients have no NVC. Trigeminal neuralgia clearly occurs and recurs in the absence of NVC.

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Radiographic outcomes of adult spinal deformity surgeries

Spinal adult deformity

Neurosurg Focus 36 (5):E13, 2014

Various surgical approaches, including open, minimally invasive, and hybrid techniques, have gained momentum in the management of adult spinal deformity. However, few data exist on the radiographic outcomes of different surgical techniques. The objective of this study was to compare the radiographic and clinical outcomes of the surgical techniques used in the treatment of adult spinal deformity.

Methods. The authors conducted a retrospective review of two adult spinal deformity patient databases, a prospective open surgery database and a retrospective minimally invasive surgery (MIS) and hybrid surgery database. The time frame of enrollment in this study was from 2007 to 2012. Spinal deformity patients were stratified into 3 surgery groups: MIS, hybrid surgery, and open surgery. The following pre- and postoperative radiographic parameters were assessed: lumbar major Cobb angle, lumbar lordosis, pelvic incidence minus lumbar lordosis (PI-LL), sagittal vertical axis, and pelvic tilt. Scores on the Oswestry Disability Index (ODI) and a visual analog scale (VAS) for both back and leg pain were also obtained from each patient.

Results. Of the 234 patients with adult spinal deformity, 184 patients had pre- and postoperative radiographs and were thus included in the study (MIS, n = 42; hybrid, n = 33; open, n = 109). Patients were a mean of 61.7 years old and had a mean body mass index of 26.9 kg/m2. Regarding radiographic outcomes, the MIS group maintained a significantly smaller mean lumbar Cobb angle (13.1°) after surgery compared with the open group (20.4°, p = 0.002), while the hybrid group had a significantly larger lumbar curve correction (26.6°) compared with the MIS group (18.8°, p = 0.045). The mean change in the PI-LL was larger for the hybrid group (20.6°) compared with the open (10.2°, p = 0.023) and MIS groups (5.5°, p = 0.003). The mean sagittal vertical axis correction was greater for the open group (25 mm) compared with the MIS group (≤ 1 mm, p = 0.008). Patients in the open group had a significantly larger postoperative thoracic kyphosis (41.45°) compared with the MIS patients (33.5°, p = 0.005). There were no significant differences between groups in terms of pre- and postoperative mean ODI and VAS scores at the 1-year follow-up. However, patients in the MIS group had much lower estimated blood loss and transfusion rates compared with patients in the hybrid or open groups (p < 0.001). Operating room time was significantly longer with the hybrid group compared with the MIS and open groups (p < 0.001). Major complications occurred in 14% of patients in the MIS group, 14% in the hybrid group, and 45% in the open group (p = 0.032).

Conclusions. This study provides valuable baseline characteristics of radiographic parameters among 3 different surgical techniques used in the treatment of adult spinal deformity. Each technique has advantages, but much like any surgical technique, the positive and negative elements must be considered when tailoring a treatment to a patient. Minimally invasive surgical techniques can result in clinical outcomes at 1 year comparable to those obtained from hybrid and open surgical techniques.

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