Management of Intracranial Meningiomas Using Keyhole Techniques

BACKGROUND: Keyhole craniotomies are increasingly being used for lesions of the skull base. Here we review our recent experience with these approaches for resection of intracranial meningiomas. METHODS: Clinical and operative data were gathered on all patients treated with keyhole approaches by the senior author from January 2012 to June 2013. Thirty-one meningiomas were resected in 27 patients, including 9 supratentorial, 5 anterior fossa, 7 middle fossa, 6 posterior fossa, and 4 complex skull base tumors. Twenty-nine tumors were WHO Grade I, and 2 were Grade II. RESULTS: The mean operative time was 8 hours, 22 minutes (range, 2:55-16:14) for skull-base tumors, and 4 hours, 27 minutes (range, 1:45-7:13) for supratentorial tumors. Simpson Resection grades were as follows: Grade I = 8, II = 8, III = 1, IV = 15, V = 0. The median postoperative hospital stay was 4 days (range, 1-20 days). In the 9 patients presenting with some degree of visual loss, 7 saw improvement or complete resolution. In the 6 patients presenting with cranial nerve palsies, 4 experienced improvement or resolution of the deficit postoperatively. Four patients experienced new neurologic deficits, all of which were improved or resolved at the time of the last follow-up. Technical aspects and surgical nuances of these approaches for management of intracranial meningiomas are discussed. CONCLUSIONS: With careful preoperative evaluation, keyhole approaches can be utilized singly or in combination to manage meningiomas in a wide variety of locations with satisfactory results

Predictive factors for beneficial application of high-frequency electromagnetics for tumour vaporization and coagulation in neurosurgery

<p>Abstract</p> <p>Objective</p> <p>To identify preoperative and intraoperative factors and conditions that predicts the beneficial application of a high-frequency electromagnetic field (EMF) system for tumor vaporization and coagulation.</p> <p>Methods</p> <p>One hundred three subsequent patients with brain tumors were microsurgically treated using the EMF system in addition to the standard neurosurgical instrumentarium. A multivariate analysis was performed regarding the usefulness (ineffective/useful/very helpful/essential) of the new technology for tumor vaporization and coagulation, with respect to tumor histology and location, tissue consistency and texture, patients' age and sex.</p> <p>Results</p> <p>The EMF system could be used effectively during tumor surgery in 83 cases with an essential contribution to the overall success in 14 cases. In the advanced category of effectiveness (very helpful/essential), there was a significant difference between hard and soft tissue consistency (50 of 66 cases vs. 3 of 37 cases). The coagulation function worked well (very helpful/essential) for surface (73 of 103 cases) and spot (46 of 103 cases) coagulation when vessels with a diameter of less than one millimeter were involved. The light-weight bayonet hand piece and long malleable electrodes made the system especially suited for the resection of deep-seated lesions (34 of 52 cases) compared to superficial tumors (19 of 50 cases).</p> <p>The EMF system was less effective than traditional electrosurgical devices in reducing soft glial tumors. Standard methods where also required for coagulation of larger vessels.</p> <p>Conclusion</p> <p>It is possible to identify factors and conditions that predict a beneficial application of high-frequency electromagnetics for tumor vaporization and coagulation. This allows focusing the use of this technology on selective indications.</p

Retractorless Surgery for Intracranial Aneurysms

Microsurgical clipping of intracranial aneurysms often requires access to the subarachnoid space deep in the brain. In the past, fixed retractors have been used to maintain the surgical corridor. However, studies have shown that fixed retraction leads to brain injuries. Here we present strategies to replace conventional fixed retractor blades with dynamic retraction so that the brain is no longer under constant pressure. We show that dynamic retraction without fixed retractors, when combined with optimal patient position and neuroprotective anesthetics, can provide the surgeon with adequate visualization of aneurysms and the patient with excellent surgical outcomes

Feasibility and biomechanics of multilevel arthroplasty and combined cervical arthrodesis and arthroplasty

© 2013 Wolters Kluwer Health, Inc. Study Design: A new experimental protocol was applied utilizing a simplified postural control model. Multiple constructs were tested nondestructively by interconnecting segmental rods to screws. Objective: To investigate how posture and distribution of segmental angles under physiological loads are affected by combined cervical arthroplasty and fusion. Summary of Background Data: Previous studies of biomechanics of multilevel arthroplasty have focused on range of motion and intradiscal pressure. No previous study has investigated postural changes and segmental angle distribution. Methods: In 7 human cadaveric C3-T1 specimens, C4-C5, C5-C6, and C6-C7 disks were replaced with ProDisc-C (Synthes). Combinations of fusion (f) adjacent to arthroplasty (A) were simulated at C4-C5, C5-C6, and C6-C7, respectively: fAA, AfA, AAf, ffA, fAf, Aff, fff. C3-C4 and C7-T1 remained intact. A compressive belt apparatus simulated normal muscle cocontraction and gravitational preload; C3-C4, C4-C5, C5-C6, C6-C7, and C7-T1 motions were tracked independently. Parameters studied were segmental postural compensation, neutral buckling, and shift in sagittal plane instantaneous axis of rotation (IAR). Results: With one or more levels unfused, the arthroplasty levels preferentially moved toward upright posture before the intact levels. Neutral buckling was greatest for 3-level arthroplasty, less for 2-level arthroplasty, and least for 1-level arthroplasty. Among the three 1-level arthroplasty groups (ffA, fAf, Aff), arthroplasty at the caudalmost level resulted in significantly greater buckling than with arthroplasty rostralmost or at mid-segment (P\u3c0.04, analysis of variance/Holm-Sidak). Although IAR location was related to buckling, this correlation did not reach significance (P=0.112). Conclusions: Arthroplasty levels provide the path of least resistance, through which the initial motion is more likely to occur. The tendency for specimens to buckle under vertical compression became greater with more arthroplasty levels. Buckling appeared more severe with arthroplasty more caudal. Buckling only moderately correlated to shifts in IAR, meaning slight malpositioning of the devices would not necessarily cause buckling

Feasible and accurate occipitoatlantal transarticular fixation: an anatomic study.

BACKGROUND: Defining the anatomic zones for the placement of occiput-C1 transarticular screws is essential for patient safety. OBJECTIVE: The feasibility and accuracy of occiput-C1 transarticular screw placement were evaluated in this anatomical study of normal cadaveric specimens. MATERIAL AND METHODS: Sixteen measurements were determined for screw entry points, trajectories, and lengths for placement of transarticular screws, as applied in the technique described by Grob, on the craniovertebral junction segments (occiput-C2) of 16 fresh human cadaveric cervical spines and 41 computed tomographic reconstructions of the craniovertebral junction. Acceptable angles for screw positioning were measured on digital x-rays. RESULTS: All 32 screws were placed accurately. As determined by dissection of the specimens, none of the screws penetrated the spinal canal. Screw insertion caused no fractures, and the integrity of the hypoglossal canal was maintained in all the disarticulated specimens. CONCLUSION: Viable transarticular occiput-C1 screw placement is possible, despite variability of the anatomy of the occipital condyle

Morphologic evaluation of cervical and lumbar facet joints: intra-articular facet block considerations.

STUDY DESIGN: Needle orientations for lumbar and cervical facet injection were measured in cadavers and compared with facet angles measured on magnetic resonance images (MRIs). OBJECTIVES: To establish facet orientation relative to clinical procedures of a facet joint block in the cervical and lumbar spine. METHODS: Needle orientation angles were measured from 20 unembalmed human cadaveric specimens (13 cervical and 7 lumbar). Spinal needles were inserted into the midpoints of the facet joint spaces from C3 to C7 and L1 to L5. Needle trajectories were measured with an optical tracking system. For comparison, facet angles from 100 clinical MRIs of lumbar spines were also measured. Facet orientations on MRIs were measured at their intersection with the transverse plane, and angles were quantified using image analysis software. RESULTS: Typical angles for insertion of the needle into the cervical facets were oriented closer to the coronal plane, whereas insertion angles for lumbar needles were oriented closer to the sagittal plane. Relative to the sagittal plane, the mean cervical angle was 72 degrees and the mean lumbar angle was 33 degrees. The insertion points of the cervical facets were a mean of 29 mm from the midsagittal plane compared with a mean of 22 mm for the lumbar facets. MRI-based facet joint angles correlated poorly with actual injection angles, which were overestimated 5 to 23 degrees, depending on the lumbar level. CONCLUSIONS: Knowledge of the quantitative anatomy of the facets may help improve clinical diagnosis and treatment. These data also may aid in constructing more realistic computer simulations

The legacy of hephaestus: The first craniotomy

Hephaestus is best known as the Greek god of metalworking, fire, and fine arts. As the only Olympian deity not endowed with physical perfection, he has been considered misfortunate among the Olympians. However, textual analysis of his myths reveals that Hephaestus was highly regarded by Greeks for his manual skills and intelligence. Furthermore, one of the myths about Hephaestus indicates that he performed the first recorded craniotomy. This text asserts that Hephaestus intentionally performed the craniotomy to remove a mass growing inside Zeus\u27 head, thereby relieving him of an excruciating headache. The successful craniotomy resulted in the birth of the goddess Athena. From a neurosurgical perspective, the story is allegorical. Nonetheless, it represents the surgical management of intracranial ailments, which is thought to have been reported in Greece centuries later by Hippocrates. Copyright © 2010 by the Congress of Neurological Surgeons

Biomechanics of a Fixed-Center of Rotation Cervical Intervertebral Disc Prosthesis

Background: Past in vitro experiments studying artificial discs have focused on range of motion. It is also important to understand how artificial discs affect other biomechanical parameters, especially alterations to kinematics. The purpose of this in vitro investigation was to quantify how disc replacement with a ball-and-socket disc arthroplasty device (ProDisc-C; Synthes, West Chester, Pennsylvania) alters biomechanics of the spine relative to the normal condition (positive control) and simulated fusion (negative control). Methods: Specimens were tested in multiple planes by use of pure moments under load control and again in displacement control during flexion-extension with a constant 70-N compressive follower load. Optical markers measured 3-dimensional vertebral motion, and a strain gauge array measured C4-5 facet loads. Results: Range of motion and lax zone after disc replacement were not significantly different from normal values except during lateral bending, whereas plating significantly reduced motion in all loading modes (P \u3c .002). Plating but not disc replacement shifted the location of the axis of rotation anteriorly relative to the intact condition (P \u3c 0.01). Coupled axial rotation per degree of lateral bending was 25% ± 48% greater than normal after artificial disc replacement (P = .05) but 37% ± 38% less than normal after plating (P = .002). Coupled lateral bending per degree of axial rotation was 37% ± 21% less than normal after disc replacement (P \u3c .001) and 41% ± 36% less than normal after plating (P = .001). Facet loads did not change significantly relative to normal after anterior plating or arthroplasty, except that facet loads were decreased during flexion in both conditions (P \u3c .03). Conclusions: In all parameters studied, deviations from normal biomechanics were less substantial after artificial disc placement than after anterior plating. © 2012 Elsevier Inc

The frequency and clinical significance of congenital defects of the posterior and anterior arch of the atlas

Object. In this study the authors investigated the anatomical, clinical, and imaging features as well as incidence of congenital defects of the C-1 arch. Methods. The records of 1104 patients who presented with various medical problems during the time between January 2006 and December 2006 were reviewed retrospectively. The craniocervical computed tomography (CT) scans obtained in these patients were evaluated to define the incidence of congenital defects of the posterior arch of C-1. In addition, 166 dried C-1 specimens and 84 fresh human cadaveric cervical spine segments were evaluated for anomalies of the C-1 arch. Results. Altogether, 40 anomalies (2.95%) were found in 1354 evaluated cases. Of the 1104 patients in whom CT scans were acquired, 37 (3.35%) had congenital defects of the posterior arch of the atlas. The incidence of each anomaly was as follows: Type A, 29 (2.6%); Type B, six (0.54%); and Type E, two (0.18%). There were no Type C or D defects. One patient (0.09%) had an anterior arch cleft. None of the reviewed patients had neurological deficits or required surgical intervention for their anomalies. Three cases of Type A posterior arch anomalies were present in the cadaveric specimens. Conclusions. Most congenital anomalies of the atlantal arch are found incidentally in asymptomatic patients. Congenital defects of the posterior arch are more common than defects of the anterior arch

Microsurgical Clipping of an Unruptured Basilar Apex Aneurysm

Unruptured posterior circulation aneurysms pose a treatment challenge. Although data supports the use of endovascular technique for select ruptured cases, in unruptured cases, there may be clinical equipoise. Furthermore, wide-necked basilar apex aneurysms commonly require the use of stents and placement of patients on dual therapy. We present a case of a healthy 50-year-old woman with an incidental basilar tip aneurysm treated via an orbitozygomatic craniotomy. This video highlights the steps of dynamic retraction, which is retraction without placement of permanent rigid retraction system, and the added maneuverability afforded by the use of the mouthpiece on the microscope