Kaith K. Almefty

Human Placenta Aneurysm Model for Training Neurosurgeons in Vascular Microsurgery

BACKGROUND: Neurosurgery, a demanding specialty, involves many microsurgical procedures that require complex skills, including open surgical treatment of intracranial aneurysms. Simulation or practice models may be useful for acquiring these skills before trainees perform surgery on human patients. OBJECTIVE: To describe a human placenta model for the creation and clipping of aneurysms. METHODS: Placental vessels from 40 human placentas that were dimensionally comparable to the sizes of appropriate cerebral vessels were isolated to create aneurysms of different shapes. The placentas were then prepared for vascular microsurgery exercises. Sylvian fissure--like dissection technique and clipping of large- and small-necked aneurysms were practiced on human placentas with and without pulsatile flow. A surgical field designed to resemble a real craniotomy was reproduced in the model. RESULTS: The human placenta has a plethora of vessels that are of the proper dimensions to allow the creation of aneurysms with dome and neck dimensions similar to those of human saccular and fusiform cerebral aneurysms. These anatomic scenarios allowed aneurysm inspection, manipulation, and clipping practice. Technical microsurgical procedures include simulation of sylvian fissure dissection, unruptured aneurysm clipping, ruptured aneurysm clipping, and wrapping; all were reproduced with high fidelity to the haptics of live human surgery. Skill-training exercises realistically reproduced aneurysm clipping. CONCLUSION: Human placenta provides an inexpensive, widely available, convenient biological tissue that can be used to create models of cerebral aneurysms of different morphologies. Neurosurgical trainees may benefit from the preoperative use of a realistic model to gain familiarity and practice with critical surgical techniques for treating aneurysms.

Comparison of Surgical Freedom and Area of Exposure in Three Endoscopic Transmaxillary Approaches to the Anterolateral Cranial Base

Objectiveu2003Endoscopic ipsilateral endonasal transmaxillary, contralateral endonasal transseptal transmaxillary, and Caldwell-Luc approaches can access lesions within the retromaxillary space and pterygopalatine fossa. We compared the exposure and surgical freedom of these transmaxillary approaches to assist with surgical decision making. Designu2003Four cadaveric heads were dissected bilaterally using the three approaches just described. Prior to dissection, stereotactic computed tomography (CT) scans were obtained on each head to obtain anatomical measurements. Surgical freedom and area of exposure were determined by stereotaxis. Main Outcome Measuresu2003Area of exposure was calculated as the extent of the orbital floor, maxillary sinus floor, nasal floor, and mandibular ramus exposed through each approach. Surgical freedom was the area through which the proximal end of the endoscope could be freely moved while moving the tip of the endoscope to the edges of the exposed area. Resultsu2003The mean exposed area was similar: 9.9u2009±u20092.5 cm(2) (Caldwell-Luc), 10.4u2009±u20092.6 cm(2) (ipsilateral endonasal), and 10.1u2009±u20092.1 cm(2) (contralateral transseptal) (pu2009>u20090.05). The surgical freedom of the Caldwell-Luc approach (113u2009±u20097 cm(2)) was greater than for either endonasal approach, 76 cm(2u2009)±u200915 (pu2009=u20090.001) (ipsilateral endonasal) and 83 cm(2)u2009±u200915 (pu2009=u20090.003) contralateral transseptal. Conclusionsu2003Our work demonstrates that the Caldwell-Luc endonasal approach offers greater surgical freedom than either approach for anterolateral skull base targets, although these approaches offer similar exposure.

Arteriovenous Malformations and Associated Aneurysms

A rteriovenous malformations (AVMs) of the brain often present complex management decisions for the treating surgeon. The surgical treatment of these lesions is ntended to eliminate the risks of intracranial hemorrhage; howver, eliminating this risk must be balanced by the risks and orbidity and mortality associated with treating the lesion. atural history studies have provided the basis for assessing the isk of hemorrhage and associated morbidity of untreated AVMs. he annual risk of intracranial hemorrhage associated with an ntreated AVM is 2%-3% per year; the risk of recurrent hemorhage is even greater. The risk of death in the event of hemorhage is approximately 10%, and the risk of a neurologic deficit is pproximately 50% (8).

Endoscopic Surgery of the Posterior Fossa: Strengths and Limitations

n this issue of WORLD NEUROSURGERY, Takemura et al. provide an anatomic review of the cerebellopontine angle I (CPA) using the retrosigmoid approach. The study places particular emphasis on the utility of the endoscope as an adjunct to microscopy for visualizing the neurovascular relationships of the region. Takemura et al. divide the CPA into three sections: superior, middle, and inferior. At the superior level, the endoscope provided superior views of the trigeminal nerve’s junctionwith the pons and the entrance into the porus of Meckel’s cave and relationship of the nerve with the superior cerebellar artery. At the middle level, it was noted that the endoscope provided views of the root exit zone of the facial nerve from the brainstem to the porus of the internal auditorymeatus,whichwere poorly visualized with the microscope. At the inferior level, with a transcondylar fossa approach, the endoscope provided expansive views of the medullary junction, dural exit of the lower cranial nerves, and vascular segments anterior to the lower cranial nerves. They conclude that the microscope provides satisfactory views of the posterior surface of the neural and vascular structures, but the proximal and distal parts of the nerves were reduced by cerebellar tissue and the temporal bone. Takemura et al. provide a rich anatomic reference of the region with descriptive comparisons of the views provided by the microscope and the endoscope. Our laboratory and others have attempted to provide quantitative metrics for comparing endoscopic approaches as well as open skull base approaches (16, 29, 40). It would have been instructive if Takemura et al. had performed a quantitative analysis to supplement the descriptive analysis. The primary challenge of these anatomic studies is translating the laboratory findings into a discrete benefit in the operative theater.

The efficacy and risks of preoperative embolization of spinal tumors

Background The goal of preoperative embolization of spinal tumors is to improve surgical outcomes by diminishing the vascular supply to the tumor to reduce intraoperative blood loss and operative time. Objective To report our institutional experience with spinal tumor embolization and review the present literature. Methods Clinical records from January 1, 2001 to December 31, 2012 were reviewed and analyzed. Angiograms were used to calculate the percentage reduction in tumor vascularity, and relevant clinical and operative data were collected and analyzed. Results Thirty-seven patients underwent preoperative spinal tumor embolization (24 metastatic and 13 primary lesions) and were included in the study. One complication resulted in transient lower extremity weakness and was attributed to post-embolization swelling, which fully resolved after surgical resection. The transient neurological complication rate was 1/37 (3%) and the permanent rate was 0/37 (0%). The average surgical estimated blood loss (EBL) was 1946u2005mL (100–7000u2005mL) and the average operative time was 330u2005min (range 164–841u2005min). After embolization, tumor blush was reduced by 83% on average. Average pre- and postoperative modified Rankin Scale scores were 2.10 and 1.36, respectively (p=0.03). Cases in which tumor blush was decreased by ≥90% (classes 1 or 2) after embolization had significantly less operative blood loss than those cases in which <90% (classes 3 or 4) was achieved (mean EBL 1391 vs 2296u2005mL, respectively, p=0.05). Conclusions Spinal tumor embolization is a safe procedure, is associated with few complications, and may improve surgical outcomes by limiting intraoperative blood loss and reducing operative time.

Surgical efficacy of minimally invasive thoracic discectomy.

We aimed to determine the clinical indications and surgical outcomes for thoracoscopic discectomy. Thoracic disc disease is a rare degenerative process. Thoracoscopic approaches serve to minimize tissue injury during the approach, but critics argue that this comes at the cost of surgical efficacy. Current reports in the literature are limited to small institutional patient series. We systematically identified all English language articles on thoracoscopic discectomy with at least two patients, published from 1994 to 2013 on MEDLINE, Science Direct, and Google Scholar. We analyzed 12 articles that met the inclusion criteria, five prospective and seven retrospective studies comprising 545 surgical patients. The overall complication rate was 24% (n=129), with reported complications ranging from intercostal neuralgia (6.1%), atelectasis (2.8%), and pleural effusion (2.6%), to more severe complications such as pneumonia (0.8%), pneumothorax (1.3%), and venous thrombosis (0.2%). The average reported postoperative follow-up was 20.5 months. Complete resolution of symptoms was reported in 79% of patients, improvement with residual symptoms in 10.2%, no change in 9.6%, and worsening in 1.2%. The minimally invasive endoscopic approaches to the thoracic spine among selected patients demonstrate excellent clinical efficacy and acceptable complication rates, comparable to the open approaches. Disc herniations confined to a single level, with small or no calcifications, are ideal for such an approach, whereas patients with calcified discs adherent to the dura would benefit from an open approach.

Management of Giant Internal Carotid Artery Aneurysms

n this issue of WORLD NEUROSURGERY, Ishishita et al. present a series of 38 patients with large or giant internal I carotid aneurysms treated with high flow extracranial-tointracranial bypass with a mean follow-up period of 46.7 months (range 8e170 months). They report an aneurysm obliteration rate of 100% with 0 recanalizations and 0 ruptures during the followup period. The graft patency rate was 94.7%. Complications included two transient neurological deficits, both completely resolved, an emergent revision for graft kinking, and an epidural abscess requiring surgical debridement.

Management of Brainstem Cavernous Malformations

Brainstem cavernous malformations are a fascinating and challenging family of lesions. Although rare, they are particularly interesting for neurosurgeons because, by definition, they arise in the eloquently dense landscape of the brainstem. They often pose difficult problems of access, making their removal potentially treacherous. Management is challenging because the risks of deficits associated with removal of a brainstem cavernous malformation must be balanced against the risks of hemorrhage, which frequently

From Narcotics to Antibiotics: Evolving Concepts in the Treatment of Lower Back Pain

Figure 1. Degenerative disc disease at L4-5 with associated Modic changes. (Used with permission from Barrow Neurological Institute.) In 1984, Barry Marshall and Robin Warren (8) identified the bacterium Helicobacter pylori in patients with chronic gastritis, duodenal ulcer, or gastric ulcers. With this shocking discovery, they attributed an infectious etiology to this common disease and effectively rewrote the chapter on the pathophysiology of peptic ulcer disease. Warren and Marshall ultimately earned the Nobel Prize in Medicine for this work. Based on the infectious source underlying the disease, “triple therapy” consisting of bismuth subsalicylate, tetracycline, and metronidazole was implemented and resulted in the eradication of the disease (5). Although this protocol has since been modified, antibiotic therapy remains the cornerstone of the management of peptic ulcers. Two studies were recently published in the European Spine Journal, reminiscent of the H. pylori and peptic ulcer story. Albert et al. (3, 4) attribute back pain associatedwith vertebral bodyModic (9) changes to an infectious etiology, and successfully managed the condition with antibiotics. They built on the work of Stirling et al. (11) who demonstrated in 2001 that herniated intervertebral discmaterial was often infectedwith the anaerobic bacteria Propionibacterium acnes. The finding was later confirmed by other investigators (1, 6, 7). In the first of the two articles, Albert et al. (3) demonstrate that microorganisms were found in 28 of 61 patients (46%) undergoing surgery for lumbar disc herniation. P. acnes was the most commonly identified organism, occurring in 86% of the infected discs. Furthermore, they found that patients with infected discs were more likely to develop Modic changes on magnetic resonance imaging (MRI) in the adjacent vertebra. New Modic changes occurred in 80% of patients with anaerobic infections, but in only 44% of sterile cases (3). The skin was prepared with stringent aseptic technique to minimize risk of contamination, herniated disc fragments were removed in five biopsies each with a separate set of sterile instruments, and samples stored at 80 C. Organisms were then detected using a combination of bacterial culture and polymerase chain reaction. The second of the two studies (4) was a double-blind randomized control trial of 162 patients with chronic lower back pain occurring after a previous disc herniation and Modic type 1 changes in adjacent vertebra. The patients were randomized to either placebo or a 100-day course of amoxicillin-clavulanate and evaluated at 100 days and at 1 year. The antibiotic group had significant improvements in all outcome measures including the

A History of the Barrow Neurological Institute

The Barrow Neurological Institute (BNI), founded in 1961, is in partnership with St. Josephs Hospital and Medical Center and part of the Catholic Healthcare West system. The BNI is a relative newcomer to academic neuroscience. However, since its inception it has grown to become an international destination for neurologic disease. This article describes the history of the institute as it has grown over the years in its commitment to excellence in patient care, education, and research.