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Philip A. Starr, Chadwick W. Christine, Philip V. Theodosopoulos, Nadja Lindsey, Deborah Byrd, Anthony Mosley and William J. Marks Jr.

Object. Chronic deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a procedure that is rapidly gaining acceptance for the treatment of symptoms in patients with Parkinson disease (PD), but there are few detailed descriptions of the surgical procedure itself. The authors present the technical approach used to implant 76 stimulators into the STNs of patients with PD and the lead locations, which were verified on postoperative magnetic resonance (MR) images.

Methods. Implantation procedures were performed with the aid of stereotactic MR imaging, microelectrode recording (MER) in the region of the stereotactic target to define the motor area of the STN, and intraoperative test stimulation to assess the thresholds for stimulation-induced adverse effects. All patients underwent postoperative MR imaging, which was performed using volumetric gradient-echo and T2-weighted fast—spin echo techniques, computational reformatting of the MR image into standard anatomical planes, and quantitative measurements of lead location with respect to the midcommissural point and the red nucleus. Lead locations were statistically correlated with physiological data obtained during MER and intraoperative test stimulation.

Conclusions. The authors' approach to implantation of DBS leads into the STN was associated with consistent lead placement in the dorsolateral STN, a low rate of morbidity, efficient use of operating room time, and robust improvement in motor function. The mean coordinates of the middle of the electrode array, measured on postoperative MR images, were 11.6 mm lateral, 2.9 mm posterior, and 4.7 mm inferior to the midcommissural point, and 6.5 mm lateral and 3.5 mm anterior to the center of the red nucleus. Voltage thresholds for several types of stimulation-induced adverse effects were predictive of lead location. Technical nuances of the surgery are described in detail.

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Aaron S. Dumont, Rod J. Oskouian Jr., Michael M. Chow and Neal F. Kassell

The basilar artery (BA) bifurcation is the most common site for aneurysms arising from the posterior circulation. Their inhospitable location, nested within the narrow confines of the interpeduncular fossa anterior to the brainstem, coupled with the rich network of adjacent critical thalamoperforating arteries irrigating the midbrain and thalamus, pose difficult anatomical obstacles for the surgeon.

The age old adage that the only cure for intracranial aneurysms remains exclusion from circulation before rupture still holds true. Although management of unruptured aneurysms in general is still controversial, unruptured aneurysms of the BA bifurcation can be treated surgically with acceptable rates of morbidity. The clinician must gather and weigh all clinical, pathological, and radiological data when formulating recommendations for the individual patient.

In the present report the authors describe their current technique for the surgical management of unruptured BA bifurcation aneurysms; this represents the culmination of the senior author's (N.K.) experience in the management of both ruptured and unruptured BA bifurcation aneurysms. A modified, right-sided subtemporal transtentorial approach has been adopted in all cases of isolated unruptured BA bifurcation aneurysms. Technical nuances are described.

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Edward C. Benzel

sublaminar cables provide the least rigidity of the three implants. Finally, screw-based constructs were observed to fail after screw backout (pullout), rather than because of vertebral fracture. This biomechanical study was executed in a methodical and careful manner. As is usually the case, however, the “devil is in the details.” A meticulously performed and reported experimental study often appears to yield relevant and clinically useful information. Experimental design, technical nuances, and assumptions, however, can substantially diminish the validity (often

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Paulo A. S. Kadri and Ossama Al-Mefty

Object. Mobilizing the temporal muscle is a common neurosurgical maneuver. Unfortunately, the cosmetic and functional complications that arise from postoperative muscular atrophy can be severe. Proper function of the muscle depends on proper innervation, vascularization, muscle tension, and the integrity of muscle fibers. In this study the authors describe the anatomy of the temporal muscle and report technical nuances that can be used to prevent its postoperative atrophy.

Methods. This study was designed to determine the susceptibility of the temporal muscle to injury during common surgical dissection. The authors studied the anatomy of the muscle and its vascularization and innervation in seven cadavers. A zygomatic osteotomy was performed followed by downward mobilization of the temporal muscle by using subperiosteal dissection, which preserved the muscle and allowed a study of its arterial and neural components.

The temporal muscle is composed of a main portion and three muscle bundles. The muscle is innervated by the deep temporal nerves, which branch from the anterior division of the mandibular nerve. Blood is supplied through a rich anastomotic connection between the deep temporal arteries (anterior and posterior) on the medial side and the middle temporal artery (a branch of the superficial temporal artery [STA]) on the lateral side.

Conclusions. Based on these anatomical findings, the authors recommend the following steps to preserve the temporal muscle: 1) preserve the STA; 2) prevent injury to the facial branches by using subfascial dissection; 3) use a zygomatic osteotomy to avoid compressing the muscle, arteries, and nerves, and for greater exposure when retracting the muscle; 4) dissect the muscle in subperiosteal retrograde fashion to preserve the deep vessels and nerves; 5) deinsert the muscle to the superior temporal line without cutting the fascia; and 6) reattach the muscle directly to the bone.

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Burak Sade and Joung H. Lee

with the distance between the nerves. Practical Implications Various technical nuances have been described in approaching the tentorial angle and superior CPA during MVD. In their analysis of 4400 MVDs (3196 for trigeminal neuralgia), McLaughlin and colleagues 10 recommended not to start the dissection from the acousticofacial nerve complex when one intends to reach trigeminal nerve, because of the concern for the retraction injury to the cochlear nerve. Others have also advocated to approach the trigeminal nerve through the tentorial cerebellar surface (that

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Excimer laser–assisted nonocclusive anastomosis

An emerging technology for use in the creation of intracranial–intracranial and extracranial–intracranial cerebral bypass

David J. Langer, Albert Van Der Zwan, Peter Vajkoczy, Leena Kivipelto, Tristan P. Van Doormaal and Cornelis A. F. Tulleken

followed by the use of an endoscope introduced through the vein graft. We have also proceeded simply by opening the graft near the anastomosis through a side slit, thus retrieving the flap under endoscopic or direct vision. This can be accomplished quite rapidly, limiting temporary occlusion time to a few minutes. Retrieval of the flap is part of the overall disadvantage of the procedural learning curve. The ELANA technique has sophistication, subtlety, and technical nuance that are real and need to be understood to perform a reliable bypass. Laboratory practice is vital

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Amin B. Kassam, Paul A. Gardner, Carl H. Snyderman, Ricardo L. Carrau, Arlan H. Mintz and Daniel M. Prevedello

relative to the optic chi-asm, 6 diaphragma sellae, 21 or third ventricle. 19 However, with expanded transsphenoidal approaches, the pituitary infundibulum and its relationship with the tumor is of equal importance, especially if preservation of pituitary function is a goal of surgery. In this report, we describe the technical nuances and key anatomical principles required for the resection of supra-diaphragmatic/suprasellar craniopharyngiomas using the EEA. In addition, a new, approach-based classification of the suprasellar extent of these tumors, as it relates to

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Giorgio Carrabba, Amir R. Dehdashti and Fred Gentili

. 5 , 12 , 13 , 16 , 21–23 , 29 , 36 , 42 , 47 , 48 , 52 , 59 , 62 Using the expanded endonasal approach, one can readily access, in a minimally invasive way, the entire central skull base from the frontal sinus anteriorly to the clivus and region of the foramen magnum and odontoid process inferiorly. 9 , 12 , 19 Proponents of these more minimally invasive endoscopic approaches cite less morbidity and equal or better resection rates. 14–16 , 21–23 , 29 In this report, we present the anatomical and technical nuances of the purely EEE approach for the treatment of

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Omar M. Arnaout, Bradley A. Gross, Christopher S. Eddleman, Bernard R. Bendok, Christopher C. Getch and H. Hunt Batjer

Mine S , Hirai S , Ono J , Yamaura A : Risk factors for poor outcome of untreated arteriovenous malformation . J Clin Neurosci 7 : 503 – 506 , 2000 25 Natarajan SK , Ghodke B , Britz GW , Born DE , Sekhar LN : Multimodality treatment of brain arteriovenous malformations with microsurgery after embolization with onyx: single-center experience and technical nuances . Neurosurgery 62 : 1213 – 1216 , 2008 26 Ondra SL , Troupp H , George ED , Schwab K : The natural history of symptomatic arteriovenous malformations of the

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Donald V. La Barge III, Perry P. Ng, Edwin A. Stevens, Nathan K. Friedline, John R. Kestle and Richard H. Schmidt

of a prospective observational study in 20 European centers . AJNR Am J Neuroradiol 25 : 39 – 51 , 2004 10 Mounayer C , Hammami N , Piotin M , Spelle L , Benndorf G , Kessler I , : Nidal embolization of brain arteriovenous malformations using Onyx in 94 patients . AJNR Am J Neuroradiol 28 : 518 – 523 , 2007 11 Natarajan SK , Ghodke B , Britz G , Born DE , Sekhar LN : Multimodality treatment of brain arteriovenous malformations with microsurgery after embolization with Onyx: single-center experience and technical nuances