Neurosurgery Blog

Neurosurgery 67[ONS Suppl 1]:ons222-ons228, 2010 DOI: 10.1227/01.NEU.0000374696.84827.22

OBJECTIVE: To evaluate the usefulness of motor evoked potential (MEP) monitoring andmapping in arteriovenous malformation surgery.

METHODS: Intraoperative MEP monitoring was performed in 21 patients whose AVMs were located near the motor area or fed by arteries related to the corticospinal tract to detect blood flow insufficiency and/or direct injury to the corticospinal tract and/or to map the motor area.

RESULTS: In 4 of 16 patients monitored for blood flow insufficiency, the MEP changed intraoperatively. In 2 patients, the changes were attributable to temporary occlusion of the feeding artery (anterior choroidal or lenticulostriate artery): 1 patient had a venous infarction around the internal capsule caused by thrombosis of the draining vein and the other bled intraoperatively from the nidus. In 17 patients, the MEP was monitored to rule out direct injury. In 1 patient, the MEP changed on coagulation of fragile vessels around the nidus in the precentral gyrus; it recovered after coagulation was discontinued. In 1 of 5 patients with MEP changes, the MEP did not recover; permanent hemiparesis developed in this patient because of venous infarction. In 1 of 11 patients subjected to MEP mapping of the motor area, we found translocation to the postcentral sulcus.

CONCLUSION: In arteriovenous malformation surgery, MEP monitoring facilitates the detection of blood flow insufficiency and/or direct injury of the corticospinal tract and mapping of the motor area. It contributes to reducing the incidence of postoperative motor paresis.

J Neurosurg 113:615–621, 2010.DOI: 10.3171/2009.9.JNS08825

Chronic subdural hematoma (CSDH), a condition much more common in the elderly, presents an increasing challenge as the population ages. Treatment strategies for CSDH include bur-hole craniostomy (BHC), twist-drill craniostomy (TDC), and craniotomy. Decision analysis was used to organize existing data and develop recommendations for effective treatment.

Methods. A Medline search was used to identify articles about treatment of CSDH. Direct assessment by health care professionals of the relative health impact of common complications and recurrences was used to generate utility values for treatment outcomes. Monte Carlo simulation and sensitivity analyses allowed comparisons across treatment strategies. A second simulation examined whether intraoperative irrigation or postoperative drainage affect the outcomes following BHC.

Results. On a scale from 0 to 1, the utility of BHC was found to be 0.9608, compared with 0.9202 for TDC (p = 0.001) and 0.9169 for craniotomy (p = 0.006). Sensitivity analysis confirmed the robustness of these values. Craniotomy yielded fewer recurrences, but more frequent and more serious complications than did BHC. There were no significant differences for BHC with or without irrigation or postoperative drainage.

Conclusions. Bur-hole craniostomy is the most efficient choice for surgical drainage of uncomplicated CSDH. Bur-hole craniostomy balances a low recurrence rate with a low incidence of highly morbid complications. Decision analysis provides statistical and empirical guidance in the absence of well-controlled large trials and despite a confusing range of previously reported morbidity and recurrence.

J Neurosurg 113:639–647, 2010.DOI: 10.3171/2010.3.JNS091385

A challenge associated with deep brain stimulation (DBS) in treating advanced Parkinson disease (PD) is the direct visualization of brain nuclei, which often involves indirect approximations of stereotactic targets. In the present study, the authors compared T2*-weighted images obtained using 7-T MR imaging with those obtained using 1.5- and 3-T MR imaging to ascertain whether 7-T imaging enables better visualization of targets for DBS in PD.

Methods. The authors compared 1.5-, 3-, and 7-T MR images obtained in 11 healthy volunteers and 1 patient with PD.

Results. With 7-T imaging, distinct images of the brain were obtained, including the subthalamic nucleus (STN) and internal globus pallidus (GPi). Compared with the 1.5- and 3-T MR images of the STN and GPi, the 7-T MR images showed marked improvements in spatial resolution, tissue contrast, and signal-to-noise ratio.

Conclusions. Data in this study reveal the superiority of 7-T MR imaging for visualizing structures targeted for DBS in the management of PD. This finding suggests that by enabling the direct visualization of neural structures of interest, 7-T MR imaging could be a valuable aid in neurosurgical procedures.

J Neurosurg 113:486–492, 2010.DOI: 10.3171/2010.1.JNS091106

The aim of this study was to compare percutaneous balloon compression (PBC) and percutaneous retrogasserian glycerol rhizotomy (PRGR) in terms of effectiveness, complications, and technical aspects.

Methods. Sixty-six consecutive PBC procedures were performed in 45 patients between January 2004 and December 2008, and 120 PRGR attempts were performed in 101 patients between January 2006 and December 2008. The PRGR procedures were not completed due to technical reasons in 19 cases. Five patients in the Balloon Compression Group and 9 patients in the Glycerol Group were lost to follow-up and were excluded from the study. The medical records and the intraoperative fluoroscopic images from the remaining cases were retrospectively examined, and the follow-up was completed with telephone contact, when necessary. The 2 groups were compared in terms of initial effect, duration of effect, and rates of complications as well as severity and type of complications.

Results. The rates for immediate pain relief were 87% for patients treated with glycerol injection and 85% for patients treated with balloon compression. The Kaplan-Meier plots for the 2 treatment modalities were similar. The 50% recurrence time was 21 months for the balloon procedure and 16 months for the glycerol procedure. When the groups were broken down by the “previous operations” criterion, the 50% recurrence time was 24 months for the Glycerol First Procedure Group, 6 months for the Balloon First Procedure Group, 8 months for the Glycerol Previous Procedures Group, and 21 months for the Balloon Previous Procedures Group. The rates of complications (excluding numbness) were 11% for PRGR and 23% for PBC, and this difference was statistically significant (chi-square test, p = 0.04).

Conclusions. Both PRGR and PBC are effective techniques for the treatment of trigeminal neuralgia, with PRGR presenting some advantages in terms of milder and fewer complications and allowing lighter anesthesia without compromise of analgesia. For these reasons the authors consider PRGR as the first option for the treatment of trigeminal neuralgia in patients who are not suitable candidates or are not willing to undergo microvascular decompression, while PBC is reserved for patients in whom the effect of PRGR has proven to be short or difficult to repeat due to cisternal fibrosis.

Acta Neurochir (2010) 152:1519–1525.DOI 10.1007/s00701-010-0723-5

The quality of surgical treatment of intracranial aneurysms is determined by complete aneurysm occlusion and restoration of flow in the parent, branching and perforating vessels. In postoperative digital subtraction angiography (DSA), unexpected aneurysm residuals and vessel occlusions are frequently detected. Here, the value of two nearly noninvasive and cost-effective techniques for intraoperative flow evaluation (near-infrared indocyanine green video angiography (ICG-VA) and microvascular Doppler sonography (mDs)) is investigated in a prospective study.

Patients and methods Over a period of 10months, the authors surgically clipped 50 aneurysms under intraoperative pre- and post-clipping evaluation of flow in the parent, branching and perforating vessels and the aneurysm sack by the two techniques. Intraoperative applicability of each technique was compared to each other and to postoperative digital subtraction angiography as standard evaluation technique.

Results Forty-five aneurysms were totally occluded without vessel compromise (90%). Intraoperatively, ICG-VA was considered useful in 43 cases (86%) and mDs in 44 cases (88%), respectively. Both techniques could compensate each other’s weak points to a certain degree; but two branch occlusions (4%) and three neck remnants (6%) were revealed by postoperative DSA.

Conclusion Both techniques have specific drawbacks that could be compensated by each other, to a certain extent. Intraoperatively, ICG-VA and mDs should not be considered competitive, but complementary. This study implicates that the combination of both applications on a routine basis assures the quality of aneurysm surgery by nearly noninvasive and cost-effective techniques. However, DSA remains the gold standard for evaluation of aneurysm occlusion.

Neurosurgery 67:824-836, 2010 DOI: 10.1227/01.NEU.0000377852.75544.E4

Surgical treatment of arachnoid cysts remains under debate. Although many authors favor endoscopic techniques, others attribute a higher recurrence rate to the endoscope.

OBJECTIVE: The authors report their experience with endoscopic procedures for arachnoid cyst.

METHODS: All pure endoscopic procedures for arachnoid cysts performed by the authors were analyzed. Particular reference was given to surgical complications and patient outcome in relation to cyst location and endoscopic technique.

RESULTS: Sixty-six endoscopic procedures were performed in 61 patients (mean age, 28 years; range, 23 days to 74 years; 35 males, 26 females). The main presenting symptoms were cephalgia (61%), hemisymptoms (18%), and macrocephalus (18%). Cyst location was temporobasal (34%), suprasellar (21%), at the cisterna quadrigemina (18%), paraxial supratentorial (16%), and various (10%). Thirty cystocisternostomies, 14 ventriculocystostomies, 12 cystoventriculostomies, and 10 ventriculocystocisternostomies were performed. The overall clinical success rate was 90%. The endoscopic technique was abandoned in 4 cases (7%). Postoperative complications were found in 16%; there was only one permanent deficit (2%). Five recurrences (8%) occurred up to 7 years after the first procedure. Of the various locations, the temporobasal cysts were the most difficult to treat with lowest clinical success (81%), highest recurrence (19%), and highest complication rate (24%). Of the various endoscopic techniques, ventriculocystostomy and ventriculocystocisternostomy reached the highest success rates with 100%.

CONCLUSIONS: Endoscopic techniques provide very good results in arachnoid cyst treatment. The most frequent cyst location is the most difficult to treat. A long-term follow-up is recommended since recurrences can occur many years after the procedure

Neurosurg Focus 29 (2):E3, 2010. (DOI: 10.3171/2010.4.FOCUS10103)

Deep brain stimulation (DBS) is the treatment of choice for otherwise healthy patients with advanced Parkinson disease who are suffering from disabling dyskinesias and motor fluctuations related to dopaminergic therapy. As DBS is an elective procedure, it is essential to minimize the risk of morbidity. Further, precision in targeting deep brain structures is critical to optimize efficacy in controlling motor features. The authors have already established an operational checklist in an effort to minimize errors made during DBS surgery. Here, they set out to standardize a strict, step-by-step approach to the DBS surgery used at their institution, including preoperative evaluation, the day of surgery, and the postoperative course. They provide careful instruction on Leksell frame assembly and placement as well as the determination of indirect coordinates derived from MR images used to target deep brain structures. Detailed descriptions of the operative procedure are provided, outlining placement of the stereotactic arc as well as determination of the appropriate bur hole location, lead placement using electrophysiology, and placement of the internal pulse generator. The authors also include their approach to preventing postoperative morbidity. They believe that a strategic, step-by-step approach to DBS surgery combined with a standardized checklist will help to minimize operating room mistakes that can compromise targeting and increase the risk of complication.

Neurosurgery 67:251-264, 2010 DOI: 10.1227/01.NEU.0000371731.20246.AC

Functional neuronavigation with intraoperative 3-dimensional (3D) ultrasound may facilitate safer brain lesion resections than conventional neuronavigation.

OBJECTIVE: In this study, functional magnetic resonance imaging (fMRI) and diffusion tensor tractography (DTT) were used to map eloquent areas. We assessed the use of fMRI and DTT for preoperative assessments and determined whether using these data together with 3D ultrasound during surgery enabled safer lesion resection.

METHODS:We reviewed 51 consecutive patients with intracranial lesions in whom fMRI with or without DTT was used to map eloquent areas. To assess a possible impact of fMRI/DTT, we reviewed and analyzed the quality of the fMRI/DTT data, any change in therapeutic strategies, lesion to eloquent area distance (LEAD), extent of resection, and clinical outcome.

RESULTS: As a result of the fMRI/DTT mapping, the therapeutic strategies were changed in 4 patients. The median tumor residue for glioma patients was 11% (n = 33) and 0% for nonglioma lesions (n = 12). For gliomas, there was a significant correlation between decreasing LEAD and increasing tumor residue. Of the glioma patients, 42% underwent gross total resection (≥ 95%) and 12% suffered neurological worsening after surgery as a result of complications. Of glioma patients with an LEAD of ≤ 5 mm, 24% underwent gross total resection and 10% experienced neurological deterioration.

CONCLUSION: This study demonstrates that preoperative fMRI and DTT had direct consequences for therapeutic strategies and indicates their impact on intraoperative strategies to spare eloquent cortex and tracts. Functional neuronavigation combined with intraoperative 3D ultrasound can, in most patients, enable resection of brain lesions with general anesthesia without jeopardizing neurological function.

Neurosurgery 67:272-277, 2010 DOI: 10.1227/01.NEU.0000371981.83022.B1

Cervical spondylotic myelopathy (CSM) is one of the leading causes of spinal cord dysfunction in the adult population. Laminoplasty is an effective decompressive procedure for the treatment of CSM.

OBJECTIVE:We present our experience with 40 patients who underwent cervical laminoplasty using titanium miniplates for CSM.

METHODS:We performed a retrospective review of the medical records of a consecutive series of patients with CSM treated with laminoplasty at the University of Rochester Medical Center or Rochester General Hospital. We documented patient demographic data, presenting symptoms, and postoperative outcome. Data are also presented regarding the general cost of constructs for a hypothetical 3-level fusion.

RESULTS: Forty patients underwent cervical laminoplasty; all were available for follow-up. The mean number of levels was 4. All patients were myelopathic, and 17 (42.5%) had signs of radiculopathy preoperatively. Preoperatively, 62.5% of patients had a Nurick grade of 2 or worse. The average follow-up was 31.3 months. The median length of stay was 48 hours. On clinical evaluation, 36 of 40 patients demonstrated an improvement in their myelopathic symptoms; 4 were unchanged. Postoperative kyphosis did not develop in any patients.

CONCLUSION: The management of CSM for each of its etiologies remains controversial. As demonstrated in our series, laminoplasty is a cost-effective, decompressive procedure for the treatment of CSM, providing a less destabilizing alternative to laminectomy while preserving mobility. Cervical laminoplasty should be considered in the management of multilevel spondylosis because of its ease of exposure, ability to decompress, effective preservation of motion, maintenance of spinal stability, and overall cost.

Acta Neurochir (2010) 152:1291–1298. DOI 10.1007/s00701-010-0637-2

Minimally invasive percutaneous single trajectory stereotactic radiofrequency amygdalohippocampectomy was used to treat mesial temporal lobe epilepsy (MTLE). The aim of the study was to evaluate complications and effectiveness of this procedure.

Materials and methods A group of 51 patients with MTLE was treated using stereotactic thermo-lesion of amygdalohippocampal complex under local anaesthesia. The target was reached through the occipital approach with a single trajectory using MRI stereotactic localisation. Thermocoagulation of the amygdalohippocampal complex was planned according to the individual anatomy of each patient. Amygdalohippocampectomy was performed using a string electrode with a 10-mm active tip, and 16–38 lesions (median=25) were performed in all patients along the 30- to 45-mm trajectory (median=35) in the amygdalohippocampal complex.

Results The procedure was well tolerated by all patients with no severe permanent morbidity; meningitis was recorded in two patients (4%), hematoma was detected in four patients, clinically insignificant in three of them, and one patient required temporary ventricular drainage (2%). Thirty-two patients were followed up over at least 2 years, and the clinical outcomes were evaluated by Engel’s classification; 25 of them (78%) were Engel I, five (16%) were Engel II, and two (6%) were Engel IV.

Conclusions Stereotactic amygdalohippocampectomy is a minimally invasive procedure with low morbidity and good results that can be the method of choice in selected patients with MTLE.

Neurosurgery 67[ONS Suppl 1]:ons00-ons00, 2010. DOI: 10.1227/01.NEU.0000354351.00684.B9

To describe a transnasal endoscopic route to the jugular foramen and the endoscopic anatomy of the infratemporal fossa.

CLINICAL PRESENTATION: Endoscopic transnasal dissection of the infratemporal fossa was performed in 3 injected fresh heads (1 head only in arteries and 2 heads in arteries and veins). Two other double-injected specimens were dissected externally (2 of them side laterally and 1 anteriorly) to compare the different views and better understand the 3-dimensionality of the region. Detailed endoscopic anatomy of the infratemporal fossa was clearly observed. The realization of a septal and posterior maxillary window allows surgeons to gain space to the jugular foramen. The ability to manage the vessels, especially the veins, and identify the muscles is mandatory. The fundamental role of the vidian canal in targeting the anterior genu of the internal carotid artery is confirmed. The role of the maxillary and mandibular branches of the trigeminal nerve and the eustachian tube in this kind of approach is critical.

CONCLUSION: A fully transnasal endoscopic route to the jugular foramen is feasible. The most important landmark for this kind of approach is the eustachian tube.

J Neurosurg 113:352–357, 2010.DOI: 10.3171/2009.10.JNS09447

Object. Several studies have revealed that the gross-total resection (GTR) of malignant brain tumors has a significant influence on patient survival. Frequently, however, GTR cannot be achieved because the borders between healthy brain and diseased tissue are blurred in the infiltration zones of malignant brain tumors. Especially in eloquent cortical areas, resection is frequently stopped before total removal is achieved to avoid causing neurological deficits. Interestingly, 5-aminolevulinic acid (5-ALA) has been shown to help visualize tumor tissue intraoperatively and, thus, can significantly improve the possibility of achieving GTR of primary malignant brain tumors. The aim of this study was to go one step further and evaluate the utility and limitations of fluorescence-guided resections of primary malignant brain tumors in eloquent cortical areas in combination with intraoperative monitoring based on multimodal functional imaging data. Methods. Eighteen patients with primary malignant brain tumors in eloquent areas were included in this prospective study. Preoperative neuroradiological examinations included MR imaging with magnetization-prepared rapid gradient echo (MPRAGE), functional MR, and diffusion tensor imaging sequences to visualize functional areas and fiber tracts. Imaging data were analyzed offline, loaded into a neuronavigational system, and used intraoperatively during resections. All patients received 5-ALA 6 hours before surgery. Fluorescence-guided tumor resections were combined with intraoperative monitoring and cortical as well as subcortical stimulation to localize functional areas and fiber tracts during surgery. Results. Twenty-five procedures were performed in 18 consecutive patients. In 24% of all surgeries, resection was stopped because a functional area or cortical tract was identified in the resection area or because motor evoked potential amplitudes were reduced in an area where fluorescent tumor cells were still seen intraoperatively. Grosstotal resection could be achieved in 16 (64%) of the surgeries with preservation of all functional areas and fiber tracts. In 2 patients presurgical hemiparesis became accentuated postoperatively, and 1 of these patients also suffered from a new homonymous hemianopia following a second resection. Conclusions. The authors’ first results show that tumor resections with 5-ALA in combination with intraoperative cortical stimulation have the advantages of both methods and, thus, provide additional safety for the neurosurgeon during resections of primary malignant brain tumors in eloquent areas. Nonetheless, more cases and additional studies are necessary to further prove the advantages of this multimodal strategy.

Am J Neuroradiol 31:1139–47. DOI 10.3174/ajnr.A2023

Aneurysm treatment by intrasacular packing has been associated with a relatively high rate of recurrence. The use of mesh tubes has recently gained traction as an alternative therapy. This article summarizes the midterm results of using an endoluminal sleeve, the PED, in the treatment of aneurysms.

MATERIALS AND METHODS: A total of 19 wide-neck aneurysms were treated in 18 patients: 10 by implantation of PEDs alone and 9 by a combination of PED and coils. Angiographic and clinical results were recorded immediately and at 6 months following treatment.

RESULTS: Immediate angiographic occlusion was achieved in 4 and flow reduction, in another 15 aneurysms. Angiography at 6 months demonstrated complete occlusion in 17 and partial filling in 1 of 18 patients. There was no difference between coil-packed and unpacked aneurysms. Of 28 side branches covered by 1 device, the ophthalmic artery was absent immediately in 1 and at 6 months in another 2 cases. One patient experienced abrupt in-stent thrombosis resulting in a transient neurologic deficit, and 1 patient died due to rupture of a coexisting aneurysm. All giant aneurysms treated with PED alone were demonstrated by follow-up cross-sectional imaging to have involuted by 6 months.

CONCLUSIONS: Treatment of large, wide-neck, or otherwise untreatable aneurysms with functional reconstruction of the parent artery may be achieved with relative safety using dedicated flowmodifying devices with or without adjunctive use of intrasaccular coil packing.

Acta Neurochir (2010) 152:1099–1116.DOI 10.1007/s00701-010-0633-6

Within the realm of neurosurgery, petroclival meningiomas are regarded as probably the most difficult tumour to be treated by microsurgery. This is due to the not infrequently large size of the tumours which, although predominantly located in the posterior fossa, may occupy more than one cranial compartment, with often significant space-occupying effect and brain stem compression. Frequent tight brain stem adherence as well as encasement of the basilar artery, its perforators and cranial nerves adds to the sometimes extreme difficulties of surgical tumour removal. Counselling patients as well as pre- and intraoperative decision making in petroclival meningiomas is even more difficult because upon clinical and radiological tumour detection, despite sometimes surprisingly large tumours, clinical symptoms are often only mild. Summarising the complicated development of petroclival meningioma surgery over the last 60 years, this paper represents the conceptual thinking of the author in regard to the treatment of petroclival meningiomas which has evolved over more than two decades, based on a special interest in these treacherous tumours, and accumulated experiences in the treatment of over 150 patients. Surgical concepts and the operative decision-making process are demonstrated in four illustrative cases.

Methods Over a period of slightly over 20 years, between January 1988 and December 2008, 161 patients with petroclival meningiomas were managed clinically by the author or under his direct surveillance in four academic neurosurgical institutions. The observation period ranged from 4 to 242 months. Thirteen patients were lost to followup so, all together, complete data were available for 148 patients. In 119 patients (80%), the tumour was large. Giant tumours accounted for 7% and 11 patients, medium-sized tumours were found in 12 patients (8%) and small tumours in only six patients (4%). Sixty-two percent of the patients had invasion of Meckel’s cave or some part of the cavernous sinus, mainly the posterior region to different degrees. All giant tumours and one third of the large tumours extended into more than one cranial fossa.

Results The treatment modalities in the 148 patients were as follows: microsurgery alone was performed in 71 patients (48%), microsurgery and adjuvant radiosurgery in 22 patients (15%) so in 93 patients (63%), altogether, microsurgery was the primary treatment. Twenty-nine patients (20%) underwent radiosurgery as their only treatment, and two patients (1%), during the very early phase of the study period, received radiotherapy. Twentyfour patients (16%) were only observed without any additional therapy. Gross total resection was achieved in 34 patients (37%), and subtotal resection, defined as removal of more than 90% of the tumour volume, was performed in another 36 patients (39%). Radical tumour removal was possible in 76% of the patients. There was no procedure-related death within 3 months post-surgery; the early post-op surgical complication rate was 31% with new neurological deficits or worsening of pre-existing deficits. During the observation period, almost all patients recovered significantly bringing the percentage of permanent neurological deficits, again mainly cranial nerve deficits, down to 22%.

Conclusions Based on the experiences of the author, the following treatment principles in petroclival meningiomas are proposed: small tumours in asymptomatic patients should be observed. If tumour growth is detected on serial magnetic resonance imaging or treatment is desired by the patient, surgery should be the first choice. Radiosurgery in growing small tumours should be reserved to patients with advanced age or significant co-morbidities. In medium-sized tumours and symptomatic patients, radical surgery should be attempted, if possible by judicious intraoperative judgement. In large and giant petroclival meningiomas, tumour resection as radical as possible judged intraoperatively with decompression of neural structures should be performed, followed by observation and, in the case of growing tumour remnants, radiosurgery. Thus, by a combined application of advanced microsurgical techniques, thoughtful, intraoperative decision making with limited surgical aggressively and, in selected patients, with small tumours or small tumour remnants simple observation or alternative or adjunct radiosurgery, excellent results as measured by tumour control and preservation of quality of life can be achieved.

Neurosurg Rev (2010) 33:325–334.DOI 10.1007/s10143-010-0254-9

The authors critically analyzed a large series of patients with hemifacial spasm (HFS) and who underwent microvascular decompression (MVD) under a prospective protocol. We describe several “lessons learned” that are required for achieving successful surgery and proper postoperative management.

The purpose of this study is to report on our experience during the previous 10 years with this procedure and we also discuss various related topics.

From April 1997 to June 2009, over 1,200 consecutive patients underwent MVD for HFS. Among them, 1,174 patients who underwent MVD for HFS with a minimum 1 year follow-up were enrolled in the study. The median follow-up period was 3.5 years (range, 1-9.3 years). Based on the operative and medical records, the intraoperative findings and the postoperative outcomes were obtained and then analyzed. At the 1- year follow-up examination, 1,105 (94.1%) patients of the total 1,174 patients exhibited a “cured” state, and 69 (5.9%) patients had residual spasms. In all the patients, the major postoperative complications included transient hearing loss in 31 (2.6%), permanent hearing loss in 13 (1.1%), transient facial weakness in 86 (7.3%), permanent facial weakness in 9 (0.7%), cerebrospinal fluid leak in three (0.25%) and cerebellar infarction or hemorrhage in two (0.17%). There were no operative deaths.

Microvascular decompression is a very effective, safe modality of treatment for hemifacial spasm. MVD is not sophisticated surgery, but having a basic understanding of the surgical procedures is required to achieve successful surgery

J Neurosurg 113:32–38, 2010.DOI: 10.3171/2009.12.JNS091073

Intracranial monitoring for temporal lobe seizure localization to differentiate neocortical from mesial temporal onset seizures requires both neocortical subdural grids and hippocampal depth electrode implantation. There are 2 basic techniques for hippocampal depth electrode implantation. This first technique uses a stereotactically guided 8-contact depth electrode directed along the long axis of the hippocampus to the amygdala via an occipital bur hole. The second technique involves direct placement of 2 or 3 4-contact depth electrodes perpendicular to the temporal lobe through the middle temporal gyrus and overlying subdural grid. The purpose of this study was to determine whether one technique was superior to the other by examining monitoring success and complications.

Methods. Between 1997 and 2005, 41 patients underwent invasive seizure monitoring with both temporal subdural grids and depth electrodes placed in 2 ways. Patients in Group A underwent the first technique, and patients in Group B underwent the second technique.

Results. Group A consisted of 26 patients and Group B 15 patients. There were no statistically significant differences between Groups A and B regarding demographics, monitoring duration, seizure localization, or outcome (Engel classification). There was a statistically significant difference at the point in time at which these techniques were used: Group A represented more patients earlier in the series than Group B (p < 0.05). The complication rate attributable to the grids and depth electrodes was 0% in each group. It was more likely that the depth electrodes were placed through the grid if there was a prior resection and the patient was undergoing a new evaluation (p < 0.05). Furthermore, Group A procedures took significantly longer than Group B procedures.

Conclusions. In this patient series, there was no difference in efficacy of monitoring, complications, or outcome between hippocampal depth electrodes placed laterally through temporal grids or using an occipital bur hole stereotactic approach. Placement of the depth electrodes perpendicularly through the grids and middle temporal gyrus is technically more practical because multiple head positions and redraping are unnecessary, resulting in shorter operative times with comparable results.

J Neurosurg Spine 13:5–16, 2010. DOI: 10.3171/2010.3.SPINE08143

Numerous techniques have been historically used for occipitocervical fusion with varied results. The purpose of this study was to examine outcomes of various surgical techniques used in patients with various disease states to elucidate the most efficacious method of stabilization of the occipitocervical junction.

Methods. A literature search of peer-reviewed articles was performed using PubMed and CINAHL/Ovid. The key words “occipitocervical fusion,” “occipitocervical fixation,” “cervical instrumentation,” and “occipitocervical instrumentation” were used to search for relevant articles. Thirty-four studies were identified that met the search criteria. Within these studies, 799 adult patients who underwent posterior occipitocervical fusion were analyzed for radiographic and clinical outcomes including fusion rate, time to fusion, neurological outcomes, and the rate of adverse events.

Results. No articles stronger than Class IV were identified in the literature. Among the patients identified within the cited articles, the use of posterior screw/rod instrumentation constructs were associated with a lower rate of postoperative adverse events (33.33%) (p < 0.0001), lower rates of instrumentation failure (7.89%) (p < 0.0001), and improved neurological outcomes (81.58%) (p < 0.0001) when compared with posterior wiring/rod, screw/plate, and onlay in situ bone grafting techniques. The surgical technique associated with the highest fusion rate was posterior wiring and rods (95.9%) (p = 0.0484), which also demonstrated the shortest fusion time (p < 0.0064). Screw/rod techniques also had a high fusion rate, fusing in 93.02% of cases. When comparing outcomes of surgical techniques depending on the disease status, inflammatory diseases had the lowest rate of instrumentation failure (0%) and the highest rate of neurological improvement (90.91%) following the use of screw/rod techniques. Occipitocervical fusion performed for the treatment of tumors by using screw/rod techniques had the lowest fusion rate (57.14%) (p = 0.0089). Traumatic causes of occipitocervical instability had the highest percentage of pain improvement with the use of screw/plates (100% improvement) (p < 0.0001).

Conclusions. Based on the existing literature, techniques that use screw/rod constructs in occipitocervical fusion are associated with very favorable outcomes in all categories assessed for all disease processes. For patients requiring occipitocervical arthrodesis for the treatment of inflammatory diseases, screw/rod constructs are associated with the most favorable outcomes, while posterior wiring and onlay in situ bone grafting is associated with the least favorable outcomes. Occipitocervical arthrodesis performed for the diagnosis of tumor is associated with the lowest rate of successful arthrodesis using screw/rod techniques, while posterior wiring and rods have the highest rate of arthrodesis. The nonspecified disease group had the lowest rate of surgical adverse events and the highest rate of neurological improvement.

Acta Neurochir (2010) 152:931–939. DOI 10.1007/s00701-010-0646-1

Meningiomas of the anterior skull base show specific characteristics, which render them difficult to handle. These tumors include olfactory groove, supra- and parasellar, anterior sphenoid ridge, cavernous sinus, and spheno-orbital meningiomas. Tumor localization and size, encasement of important structures as well as the extent of dural attachment may influence the decision for an adequate approach.

Discussion Various approaches to the anterior cranial fossa exist, each with corresponding advantages and disadvantages. Recently, endoscopic approaches have increasingly been used. In this review, the different approaches to meningiomas of the anterior cranial fossa in respect of anatomical issues, indications, and associated risks are discussed.

Neurosurgery 67:16-26, 2010 DOI: 10.1227/01.NEU.0000370008.04869.BF

This is the largest contemporary series of distal posterior cerebral artery (PCA) aneurysms treated by use of endovascular coiling and stenting as well as surgical clipping, clip wrapping, and bypass techniques. We propose a new treatment paradigm.

METHODS:The location, size, type of aneurysm, clinical presentation, treatment, complications, and outcomes associated with 34 distal PCA aneurysms in 33 patients (15 females, 18 males; mean age, 44 years) were reviewed retrospectively.

RESULTS: The most common presenting symptom was headache in 19 (58%) followed by contralateral weakness or numbness in 6 (18%) and visual changes in 4 (12%). Eight aneurysms were giant. Of the remaining 26 aneurysms, 17 were fusiform/dissecting, 5 were saccular, and 4 were mycotic. Treatment was primarily endovascular in 22 patients, 12 of whom also had a concomitant surgical bypass procedure. Nine patients underwent microsurgical clipping, and 3 underwent combined treatment of clipping and coiling and/or stenting. There were no significant differences in outcomes between the groups (P = .078). The recurrence rate in patients undergoing coiling was 22% and 0% in patients undergoing clipping. Fourteen aneurysms (41%) involved treatment with an occipital artery-to-PCA bypass or an onlay graft. Compared with their preoperative status, these patients had significantly worse outcomes than those without a bypass (P = .013).

CONCLUSION: Bypass techniques for the treatment of distal PCA aneurysms are associated with a higher rate of complications than once thought. In our new treatment paradigm, bypass is a last resort and reserved for patients in whom balloon-test occlusion fails, who refuse parent-vessel sacrifice, and who cannot undergo primary stenting with coiling or clip wrapping.