Harry R van Loveren

Publications (35)72.73 Total impact

• Article: Catheter fixation and ligation: a simple technique for ventriculostomy management following endovascular stenting.

  Justin M Sweeney, Rohit Vasan, Harry R van Loveren, A Samy Youssef, Siviero Agazzi
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  ABSTRACT: The object of this study was to describe a unique method of managing ventriculostomy catheters in patients on antithrombotic therapy following endovascular treatment of ruptured intracranial aneurysms. The authors retrospectively reviewed 3 cases in which a unique method of ventriculostomy management was used to successfully avoid catheter-related hemorrhage while the patient was on dual antiplatelet therapy. In this setting, ventriculostomy catheters are left in place and fixed to the calvarium with titanium straps effectively ligating them. The catheter is divided and the distal end is removed. The proximal end can be directly connected to a distal shunt system during this stage or at a later date if necessary. The method described in this report provided a variety of management options for patients requiring external ventricular drainage for subarachnoid hemorrhage. No patient suffered catheter-related hemorrhage. This preliminary report demonstrates a safe and effective method for discontinuing external ventricular drainage and/or placing a ventriculoperitoneal shunt in the setting of active coagulopathy or antithrombotic therapy. The technique avoids both the risk of hemorrhage related to catheter removal and reinsertion and the thromboembolic risks associated with the reversal of antithrombotic therapy. Some aneurysm centers have avoided the use of stent-assisted coiling in cases of ruptured aneurysms to circumvent ventriculostomy-related complications; however, the method described herein should allow continued use of this important treatment option in ruptured aneurysm cases. Further investigation in a larger cohort with long-term follow-up is necessary to define the associated risks of infection using this method.
  Journal of Neurosurgery 03/2013; · 2.96 Impact Factor
• Article: Paradoxical trends in the management of vestibular schwannoma in the United States.

  Tsz Lau, Raul Olivera, Timothy Miller, Katheryne Downes, Christopher Danner, Harry R van Loveren, Siviero Agazzi
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  ABSTRACT: Recent natural history studies of vestibular schwannomas (VSs) suggest that most of these tumors do not grow. The impact of these new data on management trends in the US is currently unknown. The aim in the present study was to evaluate current trends in the treatment of VS in the US by analyzing a national cancer database. The Surveillance, Epidemiology, and End Results Program is a national database maintained by the National Cancer Institute representing 26% of the US population. Data from the database were downloaded using provided software. Cases were isolated based on histology codes and the site code. Data from 2004 to 2007 were included in the analysis. The number of patients undergoing resection was compared with the number treated with beam radiation and observation, based on tumor size. Three thousand six hundred fifty cases were identified in the database. Over the study period, management choices for VSs showed a significant change only for tumors with a diameter < 2 cm. In this tumor category, a decrease in resection and an increase in radiation were observed, with observation showing a modest increase but remaining low at an average of 25%. Study data demonstrated a shift in the management of small VSs in the US between 2004 and 2007, with microsurgical removal giving way to radiation treatment and the overall rate for observation remaining low and stable. With recent literature suggesting that the majority of small tumors do not grow, the authors assert that VSs are being overtreated in the US.
  Journal of Neurosurgery 06/2012; 117(3):514-9. · 2.96 Impact Factor
• Article: Paradoxical trends in the management of unruptured cerebral aneurysms in the United States: analysis of nationwide database over a 10-year period.

  Michael C Huang, Ali A Baaj, Katheryne Downes, A Samy Youssef, Eric Sauvageau, Harry R van Loveren, Siviero Agazzi
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  ABSTRACT: The objective of this study was to characterize demographics, treatments, and outcomes in the management of unruptured cerebral aneurysms in the United States using a national healthcare database. Clinical data were derived from the Nationwide Inpatient Sample for the years 1997 through 2006. Patients with unruptured cerebral aneurysms were identified using the appropriate International Classification of Diseases, 9th Revision code (437.3). Hospitalizations, length of stay, hospital charges, discharge pattern, age and gender distribution, and nature of intervention were analyzed. A Bureau of Labor statistics tool was used to adjust hospital and national charges for inflation. Population-adjusted rates were calculated using population estimates generated by the U.S. Census Bureau. Over 100 000 records were retrieved for analysis. During the time period studied, there was a 75% increase in the number of hospitalizations associated with unruptured cerebral aneurysms. Inflation adjusted hospital charges increased by 60%, whereas the total national bill increased by 200%. Overall, length of stay decreased by 37% and in-hospital mortality rates decreased by 54%. The increasing number of hospitalizations and total national charges related to inpatient treatment of unruptured aneurysms were significantly associated with endovascular treatment rather than surgical clipping. Despite recent studies suggesting a low risk of rupture of incidentally diagnosed cerebral aneurysms, data from this study suggest an increasing trend of treatment for this entity in the United States. Furthermore, endovascular intervention is now the major driving force behind the increasing overall national charges. Given the current healthcare climate, the impact of these trends warrants discussion and debate.
  Stroke 06/2011; 42(6):1730-5. · 5.73 Impact Factor
• Article: Life without the vein of Galen: Clinical and radiographic sequelae.

  A Samy Youssef, Angela E Downes, Siviero Agazzi, Harry R Van Loveren
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  ABSTRACT: A thorough understanding of the anatomy of the pineal region, particularly venous drainage, is critical for gaining open surgical access to the pineal gland. The adverse sequelae after intraoperative venous occlusion are assumed to be catastrophic but have been scarcely reported. We report a case of pineocytoma in which the vein of Galen was ligated without postoperative adverse sequelae. Pineal region anatomy with emphasis on deep veins was reviewed in large anatomical studies. There are tremendous anatomical variations in the vein of Galen and its tributaries. Several confounding factors can be encountered during surgery and may lead to accidental sacrifice of the vein of Galen. Survival after focal occlusion of a major deep vein depends on the development of collateral circulation as shown in our case report. Venous drainage remains the cornerstone in the surgical planning of the pineal region. Anatomical variations and venous collaterals undoubtedly contributed to the mixed reports of adverse sequelae after venous sacrifice. Vein of Galen ligation may be survivable but consequences cannot be predicted without a thorough pre-ligation assessment of regional venous collateral drainage. Thorough understanding of the venous anatomy, meticulous planning of the surgical approach and avoidance of the occlusion of the vein of Galen and its major tributaries are key factors to successful pineal region surgery.
  Clinical Anatomy 03/2011; 24(6):776-85. · 1.29 Impact Factor
• Article: Management of the great mimicker: Meckel cave tumors.

  Rashid M Janjua, Kondi M Wong, Akash Parekh, Harry R van Loveren
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  ABSTRACT: Meckel cave tumors are often asymptomatic and have a sufficiently characteristic magnetic resonance imaging/computed tomography signature that allows treatment/surveillance decisions to be made without biopsy confirmation. Radiographic diagnosis requires the surgeon to be fully aware of the plethora of unusual Meckel cave lesions that mimic benign tumors when they are malignant, inflammatory, or infectious and in need of a completely different and often timely intervention. When such a diagnosis is considered, it behooves the surgeon and benefits the patient to have a percutaneous biopsy technique available. To use our recent experience with a patient with idiopathic inflammatory sensory neuropathy and another with Meckel cave lymphoma to review the management of tumors of the Meckel cave. The technique of percutaneous biopsy of Meckel cave tumors through the foramen ovale with biopsy needles is detailed. Obtaining tissue biopsy percutaneously prevents patients with Meckel cave tumors best treated with nonsurgical management from undergoing open surgical resection with its concomitant morbidity.
  Neurosurgery 12/2010; 67(2 Suppl Operative):416-21. · 2.79 Impact Factor
• Article: The anterolateral approach for the transcranial resection of pituitary adenomas: technical note.

  Siviero Agazzi, Ashraf Sami Youssef, Harry R van Loveren
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  ABSTRACT: We sought to quantify the mean surface area of the exposed diaphragma sellae and the mean sellar volume in the subfrontal and anterolateral approaches to pituitary adenomas and to detail our expansion of the superficial and deep window in the anterolateral approach. We performed a retrospective data analysis and cadaveric study in a clinical and skull base laboratory. We studied eight patients who had anterolateral approach for transcranial resection of pituitary macroadenoma and seven cadaveric specimens. Main outcome measures were degree of tumor resection, cerebrospinal fluid (CSF) leak, cranial nerve outcome, and quantification of the exposed sella via the anterior (subfrontal) and anterolateral approach. We observed complete resection in one; visual outcome: stable in three, improved in four, worsened in one; CSF leakage in two; transient CN III palsy in three; mean surface area (mm(2)) of exposed diaphragma sellae,115.3 (subfrontal approach) versus 94.7 (anterolateral approach; p = 0.1); mean sellar volume (mm(3)) exposed, 224.8 (subfrontal approach) versus 569.3 (anterolateral approach; p < 0.0001). Our technical note supports the increased exposure of sellar volume via the anterolateral approach. Despite the relatively high complication rate, complex cranial surgeons should maintain the skills and knowledge of transcranial approaches. Indeed, the rapid expansion of transsphenoidal techniques will continue to decrease the number of cases but will also continue to increase the complexity of those adenomas that are referred for transcranial resection.
  Skull Base 05/2010; 20(3):143-8. · 0.66 Impact Factor
• Article: The safety and effectiveness of a dural sealant system for use with nonautologous duraplasty materials.

  Jason S Weinstein, Kenneth C Liu, Johnny B Delashaw, Kim J Burchiel, Harry R van Loveren, Fernando L Vale, Siviero Agazzi, Mark S Greenberg, Donald A Smith, John Tew
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  ABSTRACT: The DuraSeal dural sealant system, a polyethylene glycol hydrogel, has been shown to be safe and effective when used with commercial and autologous duraplasty materials. The authors report on the safety and effectiveness of this sealant when used in conjunction with nonautologous duraplasty materials. In this retrospective, nonrandomized, multicenter study, the safety and efficacy of a dural sealant system was assessed in conjunction with primarily collagen-based nonautologous duraplasty materials in a sample of 66 patients undergoing elective cranial procedures at 3 institutions. This cohort was compared with 50 well-matched patients from the DuraSeal Pivotal Trial who were treated with this sealant system and autologous duraplasty material. The key end points of the study were the incidences of CSF leaks, surgical site infections, and meningitis 90 days after surgery. The incidence of postoperative CSF leakage was 7.6% in the study group (retrospective population) and 6.0% in the Pivotal Trial population. The incidence of meningitis was 0% and 4.0% in the retrospective and Pivotal Trial groups, respectively. There were no serious device-related adverse events or unanticipated adverse device effects noted for either population. This study demonstrates that the DuraSeal sealant system is safe and effective when used for watertight dural closure in conjunction with nonautologous duraplasty materials.
  Journal of Neurosurgery 08/2009; 112(2):428-33. · 2.96 Impact Factor
• Article: Posterior clinoidectomy: dural tailoring technique and clinical application.

  A Samy Youssef, Harry R van Loveren
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  ABSTRACT: The posterior clinoid process, a bony prominence at the superolateral aspect of the dorsum sellae, has a strategic importance in a transcavernous approach to basilar tip aneurysms. To further optimize this microsurgical technique during posterior clinoidectomy, we performed a cadaveric study of this regional anatomy, describe a technique called dural tailoring, and report initial results in the surgical treatment of upper basilar artery (BA) aneurysm. After 10 adult cadaver heads (silicone-injected) were prepared for dissection, a posterior clinoidectomy with dural tailoring was performed. The dura overlying the upper clivus was coagulated with bipolar electrocoagulation and incised. Stripping dura off the clivus and lateral reflection then exposed the ipsilateral posterior clinoid process and dorsum sellae, thus creating a dural flap. Posterior clinoidectomy with dural tailoring was then used in seven patients with upper BA aneurysms. Our stepwise modification of the posterior clinoidectomy with dural tailoring created a flap that afforded protection of the cavernous sinus and oculomotor nerve. During surgery, there were no recorded intraoperative injuries to neurovascular structures. One patient died postoperatively from morbidity related to severe-grade subarachnoid hemorrhage. Postoperative oculomotor nerve palsy occurred in 3 patients (43%). In all cases, the nerve was anatomically preserved and partial to complete recovery was recorded during the first postoperative year. This technique effectively provided exposure of retrosellar upper basilar aneurysms in seven patients (basilar tip 43% and superior cerebellar artery aneurysms 57%). Outcomes and safety are at least equivalent to or better than basilar aneurysm surgery performed without surgical adjuncts, presumably a less complex subset.
  Skull Base 05/2009; 19(3):183-91. · 0.66 Impact Factor
• Article: Delayed extrusion of hydroxyapatite cement after transpetrosal reconstruction.

  Robert G Kerr, Matthew J Hearst, Ravi N Samy, Harry R van Loveren, John M Tew, Myles L Pensak, Philip V Theodosopoulos
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  ABSTRACT: Use of hydroxyapatite cement has been advocated for closure of transpetrosal defects to decrease the incidence of cerebrospinal fluid leaks. We previously identified delayed extrusion of this cement as a significant complication associated with this closure technique and now update our long-term experience. In our retrospective review, we identified 1231 patients who underwent transpetrosal procedures by our multidisciplinary cranial base team between 1984 and 2005. Of the subgroup of 177 patients who had hydroxyapatite cement used during the closure of the procedure, 13 patients (7.3%) experienced delayed extrusion of hydroxyapatite cement. Extrusion occurred in 3 patients within 12 months and in 10 patients within 68 to 140 months. Twelve patients presented with draining fistulae and concomitant Staphylococcus aureus infection; 1 patient presented asymptomatically with a large temporal lobe abscess identified on surveillance magnetic resonance imaging. All 13 patients underwent reoperation, including 1 who underwent a second procedure. Delayed extrusion of hydroxyapatite cement resulted in significant morbidity to our patients and often presented in an indolent manner. We recommend serial examination and imaging studies in patients who have had transpetrosal closures with hydroxyapatite cement. Because of the complication rates associated with hydroxyapatite cement, we have discontinued its use.
  Neurosurgery 04/2009; 64(3):527-31; discussion 531-2. · 2.79 Impact Factor
• Chapter: Petroclival and Upper Clival Meningiomas III: Combined Anterior and Posterior Approach

  Samuel L. Barnett, Anthony L. D'Ambrosio, Siviero Agazzi, Harry R. van Loveren
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  ABSTRACT: Neurosurgeons who trained or practiced in the 1980s will painfully recollect the difficulties encountered when attacking a petroclival meningioma through the only available neurosur-gical approach at that time, the suboccipital.1,2 Although surgeons generally accepted the inevitable multiple cranial nerve palsies that resulted, the frequency and severity of paralysis caused by brain stem retraction precipitated a near moratorium on such surgery as well as ultimately stimulating the search for better surgical strategies. The search for the efficacious treatment of petroclival meningiomas culminated in the development of lateral approaches to the petroclival region, improvements in skull base surgery, and formation of a multi-disciplinary team.3–7 While the two previous chapters expertly describe the anterior and posterior transpetrosal techniques, this chapter focuses on the treatment of tumors by a combined approach. The skull base literature can appear confusing with its myriad of overlapping approaches and nonstandardized nomenclature, which often varies according to specialty. Therefore, we favor a component-based nomenclature that lists the individual approaches from which a larger approach is built. Using a building block strategy to design the operative approach, we keep a complex operation as simple as possible, as small as possible, and as big as necessary. Our approaches are designed to be minimally neuroinvasive and externally cosmetic. Throughout the chapter, frequently asked questions (FAQs) of practical use at the time of surgery are interspersed to further assist the reader.
  12/2008: pages 425-432;
• Article: Sudden blindness as a complication of percutaneous trigeminal procedures: mechanism analysis and prevention.

  Siviero Agazzi, Stanley Chang, Mitchell D Drucker, A Samy Youssef, Harry R Van Loveren
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  ABSTRACT: The authors describe the case of a 76-year-old man in whom reversible sudden blindness developed after a percutaneous balloon compression rhizotomy for trigeminal neuralgia. His eye became tense and swollen with intraocular pressures of 66 mm Hg. Acetazolamide was administered, and visual acuity (20/50) returned within several months. Despite correct needle placement, the intraocular pressure rose acutely because of transient occlusion of the orbital venous drainage through the cavernous sinus; this was reversed with aggressive medical treatment. In cadaveric studies (dried skull and formalin-fixed head), the authors studied the mechanism of optic nerve penetration. Their findings showed that excessive cranial angulation of the needle with penetration of the inferior orbital fissure can directly traumatize the optic nerve in the orbital apex. Direct trauma to the optic nerve can therefore be prevented by early and repeated confirmation of the needle trajectory with lateral fluoroscopy before penetration of the foramen ovale.
  Journal of Neurosurgery 11/2008; 110(4):638-41. · 2.96 Impact Factor
• Article: Microsurgical and endoscopic anatomy of Liliequist's membrane: a complex and variable structure of the basal cisterns.

  Sebastien C Froelich, Khaled M Abdel Aziz, Paul D Cohen, Harry R van Loveren, Jeffrey T Keller
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  ABSTRACT: Descriptions of Liliequist's membrane, as reported in the literature, vary considerably. In our cadaveric study of Liliequist's membrane, we attempted to clarify and define its anatomic features and boundaries, as well as its relationship with surrounding neurovascular structures. We describe the embryology of this membrane as a remnant of the primary tentorium. The clinical significance of our findings is discussed with respect to third ventriculostomy and surgical approaches to basilar tip aneurysms, suprasellar arachnoid cysts, and perimesencephalic hemorrhage. Thirteen formalin-fixed adult cadaveric heads were injected with colored silicone. After endoscopic exploration of Liliequist's membrane, a bilateral frontal craniotomy was performed, and the frontal lobes were removed to fully expose Liliequist's membrane. Liliequist's membrane is a complex and highly variable structure that is composed of either a single membrane or two leaves. The membrane was absent in two specimens without any clear demarcation between the interpeduncular, prepontine, and chiasmatic cisterns. Understanding the variable anatomy of Liliequist's membrane is important, particularly to improve current and forthcoming microsurgical and endoscopic neurosurgical procedures. It is important as a surgical landmark in various neurosurgical operations and in the physiopathology of several pathological processes (suprasellar arachnoid cysts and perimesencephalic hemorrhage).
  Neurosurgery 08/2008; 63(1 Suppl 1):ONS1-8; discussion ONS8-9. · 2.79 Impact Factor
• Article: Quantification of the frontotemporal orbitozygomatic approach using a three-dimensional visualization and modeling application.

  Anthony L D'Ambrosio, J Mocco, Todd C Hankinson, Jeffrey N Bruce, Harry R van Loveren
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  ABSTRACT: We sought to simulate the frontotemporal orbitozygomatic (FTOZ) craniotomy in a three-dimensional virtual environment on patient-specific data and to quantify the exposure afforded by the FTOZ while simulating controlled amounts of brain retraction. Four computed tomographic angiograms were reconstructed with commercially available software (Amira 4.1.1; Mercury Computer Systems, Inc., Chelmsford, MA), and virtual FTOZ craniotomies were performed bilaterally (n = 8). Brain retraction was simulated at 1 and 2 cm. Surgical freedom and projection angle were measured and compared at each stage of the FTOZ. At 1 cm of retraction, surgical freedom increased by 27 +/- 14% for the removal of the orbital rim and by 31 +/- 18% for FTOZ (P < 0.01) when compared with frontotemporal (FT) craniotomy. At 2 cm of retraction, surgical freedom increased by 15 +/- 5% and 26 +/- 8% for the removal of the orbital rim and FTOZ, respectively (P < 0.01). With increased retraction, surgical freedom increased by 100 +/- 26%, 81 +/- 15%, and 82 +/- 27% for the FT, removal of the orbital rim, and FTOZ craniotomies, respectively (P < 0.001). Projection angle increased by 24.2% when orbital rim removal was added to the FT craniotomy (P < 0.01). Surgical freedom increases significantly at every step of the FTOZ craniotomy. This effect is less robust when brain retraction is increased. Brain retraction alone has a greater impact on surgical freedom than bone removal alone. Projection angle is significantly increased when orbital rim removal is added to the FT craniotomy. This model overcomes two major limitations of cadaver-based models: quantification of brain retraction and incorporation of patient-specific anatomy.
  Neurosurgery 03/2008; 62(3 Suppl 1):251-60; discussion 260-1. · 2.79 Impact Factor
• Article: Refinement of the extradural anterior clinoidectomy: surgical anatomy of the orbitotemporal periosteal fold.

  Sebastien C Froelich, Khaled M Abdel Aziz, Nicholas B Levine, Philip V Theodosopoulos, Harry R van Loveren, Jeffrey T Keller
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  ABSTRACT: Extradural removal of the anterior clinoid process is technically challenging because of the limited exposure. In our study of the extradural anterior clinoidectomy, we describe anatomic details and landmarks to facilitate sectioning of the orbitotemporal periosteal fold and elevation of the temporal fossa dura from the superior orbital fissure. We assess the morbidity associated with these procedures as well as compare the indications, advantages, and disadvantages of intra-versus extradural clinoidectomy. Of five formalin-fixed cadaveric heads, four were used for cadaveric dissections and one was used for histological examination. Sectioning of the orbitotemporal periosteal fold revealed a cleavage plane between the temporal fossa dura and a thin layer of connective tissue that covers the superior orbital fissure. The lacrimal nerve coursed immediately medial to this surgically created cleavage plane. The superior orbital vein crossed laterally under the cranial nerves, which pass through the superior orbital fissure. This vein is particularly vulnerable as it is composed only of endothelium and a basal membrane. Both intra- and extradural techniques for anterior clinoidectomy are important parts of the neurosurgical armamentarium. Sharp incision of the orbitotemporal periosteal fold to increase the extradural exposure of the anterior clinoid process should be made at the level of the sphenoid ridge and restricted to the periosteal bridge. Subsequent blunt elevation of the temporal fossa dura should be performed; however, peeling of the temporal fossa dura should be limited to avoid cranial nerve morbidity.
  Neurosurgery 12/2007; 61(5 Suppl 2):179-85; discussion 185-6. · 2.79 Impact Factor
• Article: Refinement of interbody implant testing in goats: a surgical and morphometric rationale for selection of a cervical level. Laboratory investigation.

  Siviero Agazzi, Harry R van Loveren, Creighton J Trahan, Wesley M Johnson
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  ABSTRACT: The authors provide a surgical description of the ventral approach to the cervical spine in a goat model and identify selection of the most appropriate level for testing interbody devices. These constructs are designed for implantation in humans during anterior cervical discectomy and fusion. Such description and guidelines for level selection have never been published in either the medical or veterinarian literature. The study comprised three phases: surgical, anatomical, and morphometric. Six goats underwent ventral approaches and were later killed; their necks were dissected and the cervical spines were processed to obtain clean specimens of the vertebral bodies. Measurements were made at each level using a contact digitizer. The anterolateral bone spurs, called alar processes, and the increased thickness of the longus colli muscle are the surgically relevant characteristics in the goat. The morphometric analysis showed that C2-3 is the most suitable level for implantation of interbody devices. The vertebral endplates at the C2-3 level are relatively flat and parallel to each other, and are perpendicular to the spinal canal axis. More distally, the endplates adopt a more curved arrangement, and the endplate angle becomes significantly greater than 90 degrees. The authors describe anatomical landmarks that are important to safely and effectively perform a ventral cervical spinal approach in the goat. The authors' model identifies C2-3 as the most appropriate level for animal testing of cervical implants because of its similarity to human anatomy. Further study with rigorous biomechanical range of motion evaluation of each caprine cervical level is needed.
  Journal of Neurosurgery Spine 12/2007; 7(5):549-53. · 1.53 Impact Factor
• Article: Clival incidentaloma.

  Peter Nakaji, Harry R van Loveren, Siviero Agazzi, Charles Teo
  Skull Base Surgery 12/2006; 16(4):219-22. · 0.66 Impact Factor
• Article: The subtemporal interdural approach to dumbbell-shaped trigeminal schwannomas: cadaveric prosection.

  Samy Youssef, Eun-Young Kim, Khaled M A Aziz, Salah Hemida, Jeffrey T Keller, Harry R van Loveren
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  ABSTRACT: Successful resection of dumbbell-shaped trigeminal schwannomas via a subtemporal interdural approach requires an understanding of both the anatomy related to the bone dissection of the petrous apex (Kawase's triangle or quadrilateral) and meningeal anatomy. We studied the meningeal anatomy related to this approach and describe the dural incisions and stepwise mobilization. Meningeal anatomy around Meckel's cave and porus trigeminus was examined during the subtemporal interdural anterior transpetrosal approach in both sides of 15 cadaveric heads. Histological study of the Meckel's cave region was performed in two cadaveric heads. The Gasserian ganglion and trigeminal roots have two layers of dura propria on their dorsolateral surface: an inner layer from the posterior fossa dura propria that constitutes the dorsolateral wall of Meckel's cave and an outer layer from the dura propria of the middle fossa. The cleavage plane between these two layers continues distally as the cleavage plane between the epineural sheaths of the trigeminal divisions and the dura propria of the middle fossa. This cleavage plane serves as the anatomic landmark for the interdural exposure of the contents of Meckel's cave. The superior petrosal sinus is sectioned at the medial aspect of Kawase's triangle and reflected along with the porus trigeminus roof. Understanding the critical meningeal architecture in and around Meckel's cave allows experienced cranial neurosurgeons to develop a subtemporal interdural approach to dumbbell-shaped trigeminal schwannomas that effectively converts a multiple-compartment tumor into a single-compartment tumor. Dural incisions and stepwise mobilization complements our previous description of the bony dissection for this approach.
  Neurosurgery 11/2006; 59(4 Suppl 2):ONS270-7; discussion ONS277-8. · 2.79 Impact Factor
• Article: Transcranial surgery for pituitary adenomas.

  A Samy Youssef, Siviero Agazzi, Harry R van Loveren
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  ABSTRACT: Although the transsphenoidal approach is the preferred approach to the vast majority of pituitary tumors with or without suprasellar extension, the transcranial approach remains a vital part of the neurosurgical armamentarium for 1 to 4% of these tumors. The transcranial approach is effective when resection becomes necessary for a portion of a pituitary macroadenoma that is judged to be inaccessible from the transsphenoidal route because of isolation by a narrow waist at the diaphragma sellae, containment within the cavernous sinus lateral to the carotid artery, projection anteriorly onto the planum sphenoidale, or projection laterally into the middle fossa. The application of a transcranial approach in these circumstances may still be mitigated by response to prolactin inhibition of prolactinomas, the frequent lack of necessity to remove asymptomatic nonsecretory adenomas from the cavernous sinus, and the lack of evidence that sustained chemical cures can be reliably achieved by removal of secretory adenomas (adrenocorticotropic hormone, growth hormone) from the cavernous sinus. Cranial base surgical techniques have refined the surgical approach to pituitary adenomas but have had less effect on actual surgical indications than anticipated. Because application of the transcranial approach to pituitary adenomas is and should be rare in clinical practice, it is useful to standardize the technique to a default mode with which the surgical team is most experienced and, therefore, most comfortable. Our default mode for transcranial pituitary surgery is the frontotemporal-orbitozygomatic approach.
  Neurosurgery 08/2005; 57(1 Suppl):168-75; discussion 168-75. · 2.79 Impact Factor
• Source

  Available from: e-flanc.net

  Article: Microvascular retractor: a new concept of retracting and repositioning cerebral blood vessels.

  A Samy Youssef, Harry R van Loveren
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  ABSTRACT: In this technical note, we report our results with a newly designed retractor blade that can be directly applied for the retraction and repositioning of cerebral blood vessels and delicate neural structures. This new malleable retractor with a semicircular tip was designed to fit in the flexible arms of a self-retaining retractor system. After prototype evaluation and optimization in laboratory studies, we used the new retractor in 15 patients during surgical procedures that included retraction of the internal carotid artery during aneurysm clipping, expansion of the surgical window, and transposition of cranial nerves. No intraoperative injuries occurred to neurovascular structures. The retractor blade remained stable on pulsating vessels during the procedure and largely preserved the vessel diameter. The new retractor incorporates the existing advantages offered by flexible self-retaining retractor blades with those features that adapt to blood vessel retraction. Rather than concentrating force at one point as typical retractors do, the semicircular tip distributes the retraction force over multiple points along its circumference.
  Neurosurgery 08/2005; 57(1 Suppl):199-202; discussion 199-202. · 2.79 Impact Factor
• Article: Large sphenoid wing meningiomas involving the cavernous sinus: conservative surgical strategies for better functional outcomes.

  Khaled M Abdel-Aziz, Sebastien C Froelich, Elias Dagnew, Walter Jean, John C Breneman, Mario Zuccarello, Harry R van Loveren, John M Tew
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  ABSTRACT: The ability to resect meningiomas that involve the medial and anterior compartments of the cavernous sinus has been refuted. In this retrospective study, we determined the efficacy of total resection of meningiomas that invade the cavernous sinus but are restricted to the lateral compartment. We reviewed the charts of 38 consecutive patients with sphenocavernous, clinoidocavernous, and sphenoclinoidocavernous meningiomas who underwent surgical treatment. We assessed early and late cranial nerve morbidity, extent of resection, and long-term outcome (mean, 96 mo). In all patients, tumors exceeded 3 cm diameter. In 22 of 24 patients, total microscopic excision was achieved in tumors that involved only the lateral compartment of the cavernous sinus and touched or partially encased the cavernous internal carotid artery (i.e., modified Hirsch Grades 0 and 1, respectively). In 2 of 24 patients, remaining tumor infiltrated the superior orbital fissure. All 14 patients who had tumors that encased (with or without narrowing) the cavernous segment of the internal carotid artery (Hirsch Grades 2-4) underwent incomplete resection. Among 38 patients, mortality was 0%, late cranial nerve deficits remained in 6 (16%), and late Karnofsky Performance Scale scores exceeded 90 in 34 patients (90%). Four patients (10.5%) developed a recurrence or regrowth. Of 20 patients who were treated with either linear accelerator-based stereotactic radiosurgery or fractionated conformal radiotherapy, 11 had residual tumor and a moderate to high proliferative index, 4 had atypical tumors and 1 had angioblastic meningioma after total excision, 2 had regrowth, and 2 had recurrent tumors. In 18 (90%) of the 20 patients who underwent radiation, tumor size was reduced or controlled. On the basis of this study and a review of the literature, we demonstrate that sphenocavernous, clinoidocavernous, and sphenoclinoidocavernous meningiomas of Hirsch Grades 0 and 1 can be excised from the lateral compartment of the cavernous sinus without postoperative mortality and with acceptable rates of morbidity. Residual tumor in the medial compartment (Hirsch Grades 2-4) may be treated with some form of radiation therapy or observation.
  Neurosurgery 07/2004; 54(6):1375-83; discussion 1383-4. · 2.79 Impact Factor