Search tips
Search criteria

Results 1-20 (20)

Clipboard (0)

Select a Filter Below

Year of Publication
more »
1.  Use of a Conformational Switching Aptamer for Rapid and Specific Ex Vivo Identification of Central Nervous System Lymphoma in a Xenograft Model 
PLoS ONE  2015;10(4):e0123607.
Improved tools for providing specific intraoperative diagnoses could improve patient care. In neurosurgery, intraoperatively differentiating non-operative lesions such as CNS B-cell lymphoma from operative lesions can be challenging, often necessitating immunohistochemical (IHC) procedures which require up to 24-48 hours. Here, we evaluate the feasibility of generating rapid ex vivo specific labeling using a novel lymphoma-specific fluorescent switchable aptamer. Our B-cell lymphoma-specific switchable aptamer produced only low-level fluorescence in its unbound conformation and generated an 8-fold increase in fluorescence once bound to its target on CD20-positive lymphoma cells. The aptamer demonstrated strong binding to B-cell lymphoma cells within 15 minutes of incubation as observed by flow cytometry. We applied the switchable aptamer to ex vivo xenograft tissue harboring B-cell lymphoma and astrocytoma, and within one hour specific visual identification of lymphoma was routinely possible. In this proof-of-concept study in human cell culture and orthotopic xenografts, we conclude that a fluorescent switchable aptamer can provide rapid and specific labeling of B-cell lymphoma, and that developing aptamer-based labeling approaches could simplify tissue staining and drastically reduce time to histopathological diagnoses compared with IHC-based methods. We propose that switchable aptamers could enhance expeditious, accurate intraoperative decision-making.
PMCID: PMC4398547  PMID: 25876071
2.  Clipping of a Mycotic Basilar Trunk Aneurysm under Cardiac Arrest in a Pregnant AIDS Patient 
Skull Base  2010;20(6):459-463.
We present the first case of a coccidioidomycosis mycotic anterior inferior cerebellar artery (AICA) aneurysm that was clipped under hypothermic cardiac standstill in a pregnant acquired immunodeficiency syndrome (AIDS) patient. A 24-year-old pregnant AIDS patient presented with intraventricular hemorrhage and hydrocephalus. Angiography revealed an 8-mm basilar trunk aneurysm with the right AICA protruding from the side wall of the aneurysm. The patient underwent a retrosigmoid craniotomy and direct clipping of the aneurysm under hypothermic cardiac standstill. At presentation, the patient had a poor grade due to subarachnoid and intraventricular hemorrhage. Despite her large posterior circulation aneurysm in the setting of AIDS with extensive coccidioidomycosis meningitis, the lesion was clipped successfully. To do so required the full range of neurosurgical repertoire, including a skull base approach and hypothermic cardiac standstill.
PMCID: PMC3134816  PMID: 21772805
Coccidioidomycosis meningitis; hypothermic cardiac standstill; mycotic aneurysm
3.  Progress of women in neurosurgery 
Despite advances in issues related to gender equity, barriers to recruiting and retaining women in neurosurgery continue to exist. At the same time, the overall projected shortage of neurosurgeons suggests that women will be vital to the long-term success of the field. Attracting women to neurosurgery can capitalize on strategies, such as mentoring, teaching leadership and negotiating skills, and job sharing or dual training tracks to name a few, that would benefit both men and women passionate about pursuing neurosurgery. Ultimately, personal and institutional accountability must be evaluated to ensure that the best and brightest candidates, regardless of gender, are recruited to neurosurgical programs to promote the health of our challenging but most satisfying profession.
PMCID: PMC3205553  PMID: 22059098
History; neurosurgery; recruitment; women
4.  Postoperative Acute Sialadenitis after Skull Base Surgery 
Skull Base  2008;18(2):129-134.
During retrosigmoid and far-lateral skull base surgical approaches, the head may be positioned at the extreme limits of rotation and flexion. In rare instances, patients may develop acute sialadenitis after surgery as a result of this positioning technique. Over a 4-year period, five patients developed postoperative sialadenitis after undergoing either a retrosigmoid craniotomy in the supine position (n = 4) or a far-lateral craniotomy in the park-bench position. Based on all the retrosigmoid and far-lateral approaches performed by the senior author (RFS), the incidence of sialadenitis was 0.84%. In all five patients, the acute sialadenitis was not clinically apparent at the conclusion of the operation. However, the diagnosis was evident within 4 hours of surgery. In each case, the neck swelling in the vicinity of the submandibular gland was contralateral to the craniotomy site. All patients were treated with intravenous hydration and antibiotic therapy. One patient was extubated immediately after surgery with no obvious evidence of sialadenitis. However, she required emergent reintubation due to airway compromise. The mechanism of acute sialadenitis in these patients was obstruction of the salivary duct caused by surgical positioning. This previously unreported observation in patients undergoing skull base surgery deserves consideration during perioperative and postoperative management.
PMCID: PMC2435476  PMID: 18769650
Skull base surgery; sialadenitis; far lateral; retrosigmoid
5.  Middle Cerebral Artery Stenosis: Endovascular and Surgical Options 
Skull Base  2005;15(3):175-189.
Atherosclerotic middle cerebral artery stenosis is a rare but potentially devastating cause of cerebral ischemia and stroke. While medical management remains the mainstay for stroke prevention, surgical and/or endovascular intervention is indicated in selected patients. This article reviews the role of surgery and endovascular techniques in the treatment of middle cerebral artery stenosis based on its natural history, pathophysiology, and prognosis when treated medically.
PMCID: PMC1214704  PMID: 16175228
Middle cerebral artery stenosis; surgery; bypass; stenting; endovascular; angioplasty
6.  Anterior Communicating Artery Aneurysm Following Radiation Therapy for Optic Glioma: Report of a Case and Review of the Literature 
Skull Base  2004;14(3):169-173.
A 42-year-old female presented with subarachnoid hemorrhage (SAH), presumably from a radiation-induced anterior communicating artery aneurysm. Six years earlier, she had undergone radiation treatment for an optic glioma that was diagnosed based on imaging criteria. The aneurysm was successfully clipped, and the optic glioma was biopsied to verify the diagnosis histologically. Radiation-induced cerebral aneurysms often manifest with a fatal SAH. These aneurysms typically develop in the field of radiation and are diagnosed a mean of 8.52 years after radiation. Rarely, the aneurysm sac thromboses spontaneously. Clipping or coiling of the aneurysm can be an effective treatment.
PMCID: PMC1151688  PMID: 16145601
Intracranial aneurysm; subarachnoid hemorrhage; optic glioma; radiation therapy
7.  Editors' Response 
Skull Base  2001;11(3):225.
PMCID: PMC1656853
8.  Return of Olfaction after Gross Total Resection of an Olfactory Groove Meningioma 
Skull base surgery  1998;8(4):229-231.
Patients with olfactory, groove meningiomas may present with anostnia, Surgery in patients with intact olfaction can also lead to anosmia when the olfactory nerves are sacrified. Olfaction can be preserved by using the prerional approach and microsurgical technique. To our knowledge; however, the recovery of olfaction after resection of an olfactory groove meningroma has not been reported. We therefore describe a patient who presented with anosmia whose evaluation revealed a large olfactory groove meningioma. She underwent a bifrontal approach for microsurgical gross bilateral excision of the tumor. At her 6-month follow-up examination, her olfaction, as measured by formal testing, had recovered.
PMCID: PMC1656706  PMID: 17171072
10.  Reevaluating the imaging definition of tumor progression: perfusion MRI quantifies recurrent glioblastoma tumor fraction, pseudoprogression, and radiation necrosis to predict survival 
Neuro-Oncology  2012;14(7):919-930.
INTRODUCTION: Contrast-enhanced MRI (CE-MRI) represents the current mainstay for monitoring treatment response in glioblastoma multiforme (GBM), based on the premise that enlarging lesions reflect increasing tumor burden, treatment failure, and poor prognosis. Unfortunately, irradiating such tumors can induce changes in CE-MRI that mimic tumor recurrence, so called post treatment radiation effect (PTRE), and in fact, both PTRE and tumor re-growth can occur together. Because PTRE represents treatment success, the relative histologic fraction of tumor growth versus PTRE affects survival. Studies suggest that Perfusion MRI (pMRI)–based measures of relative cerebral blood volume (rCBV) can noninvasively estimate histologic tumor fraction to predict clinical outcome. There are several proposed pMRI-based analytic methods, although none have been correlated with overall survival (OS). This study compares how well histologic tumor fraction and OS correlate with several pMRI-based metrics. METHODS: We recruited previously treated patients with GBM undergoing surgical re-resection for suspected tumor recurrence and calculated preoperative pMRI-based metrics within CE-MRI enhancing lesions: rCBV mean, mode, maximum, width, and a new thresholding metric called pMRI–fractional tumor burden (pMRI-FTB). We correlated all pMRI-based metrics with histologic tumor fraction and OS. RESULTS: Among 25 recurrent patients with GBM, histologic tumor fraction correlated most strongly with pMRI-FTB (r = 0.82; P < .0001), which was the only imaging metric that correlated with OS (P<.02). CONCLUSION: The pMRI-FTB metric reliably estimates histologic tumor fraction (i.e., tumor burden) and correlates with OS in the context of recurrent GBM. This technique may offer a promising biomarker of tumor progression and clinical outcome for future clinical trials.
PMCID: PMC3379799  PMID: 22561797
glioblastoma; histologic tumor fraction; perfusion MRI; pseudoprogression; radiation necrosis; recurrent; relative cerebral blood volume; survival
11.  Neurosurgery 
Western Journal of Medicine  1986;145(1):83.
PMCID: PMC1306820  PMID: 18750020
12.  Accessing the Basilar Artery Apex: Is the Temporopolar Transcavernous Route an Anatomically Advantageous Alternative? 
Skull Base  2011;21(1):23-30.
The restricted operative field, difficulty of obtaining proximal vascular control, and close relationship to important anatomic structures limit approaches to basilar apex aneurysms. We used a cadaveric model to compare three surgical transcavernous routes to the basilar apex in the neutral configuration. Five cadaveric heads were dissected and analyzed. Working areas and length of exposure provided by the transcavernous (TC) approach via pterional, orbitozygomatic, and temporopolar (TP) routes were measured along with assessment of anatomic variation for the basilar apex region. In the pterional TC and orbitozygomatic TC approaches, the mean length of exposure of the basilar artery measured 6.9 and 7.2 mm, respectively (p = NS). The mean length of exposure in a TP TC approach increased to 9.3 mm (p < 0.05). Compared with the pterional and orbitozygomatic approaches, the TP TC approach provided a larger peribasilar area of exposure ipsilaterally and contralaterally (p < 0.05). The multiplanar working area related to the TP TC approach was 77.7 and 69.5% wider than for the pterional TC and orbitozygomatic TC, respectively. For a basilar apex in the neutral position, the TP TC approach may be advantageous, providing a wider working area for the basilar apex region, improving maneuverability for clip application, fine visualization of perforators, and better proximal control.
PMCID: PMC3312409  PMID: 22451796
Basilar artery aneurysm; transcavernous approach; temporopolar approach; pterional approach; orbitozygomatic approach; anatomic study
13.  The Challenge of Access to the Pontomesencephalic Junction: An Anatomical Study of Lateral Approach and Exposure 
Skull Base  2010;20(5):311-320.
We quantitatively compared relative merits of lateral approaches to the pontomesencephalic junction (PMJ): anterior petrosectomy, subtemporal transtentorial, posterior petrosectomy, and retrosigmoid transtentorial. In dissected cadaveric heads, lengths of exposure were measured anteriorly from CN V along the pontomesencephalic sulcus (PMS); posterosuperiorly along the lateral mesencephalic sulcus (LMS); and posteroinferiorly along the interpeduncular sulcus (IPS). Subtemporal transtentorial approach provided best anterior exposure along the PMS (23.8 ± 4.5 mm). Posterosuperior exposures were comparable for all approaches except anterior petrosectomy (limited). Posteroinferior exposure was most with subtemporal transtentorial approach (13.2 ± 2.8 mm). CN V entry/exit point was identified through all approaches, except for subtemporal transtentorial; shortest surgical depth with posterior petrosectomy was 43.7 ± 5.5 mm. PMS-LMS-IPS convergence point: reached through all approaches, except for anterior petrosectomy (limited); shortest surgical depth with posterior petrosectomy was 40.3 ± 4.3 mm. Anterior petrosectomy provides direct anterolateral views of the pons not afforded by subtemporal approach. Subtemporal transtentorial approach provides optimal posterolateral view to the PMJ and cerebellar peduncles. Retrosigmoid transtentorial approach offers wide exposure of the lateral surface, limited on the posteroinferior PMJ by the cerebellum. The small opening of posterior petrosectomy creates an awkward corridor to anterior PMJ targets but provides a direct and shortest route to the cerebellar peduncles.
PMCID: PMC3023326  PMID: 21358994
Petrosal approach; pontomesencephalic junction; retrosigmoid approach; subtemporal approach; surgical-anatomical study
14.  Anatomical Relationships of Intracavernous Internal Carotid Artery to Intracavernous Neural Structures 
Skull Base  2010;20(5):327-336.
The objective is to correlate the intracavernous internal carotid artery (ICA) with the position of the intracavernous neural structures. The cavernous sinuses of nine injected cadaveric heads were dissected bilaterally. As measured on computed tomographic angiograms from 100 adults, anatomical relationships and measurements of intracavernous ICA and neural structures were studied and correlated to the intracavernous ICA curvature. Intracavernous ICAs were classified as normal and redundant. The meningohypophyseal trunk (MHT) of normal ICAs appeared to be closely related to the abducens nerve compared with redundant ICAs (5.5 ± 2.1 mm versus 10.0 ± 2.5 mm, respectively; p = 0.001). The position of the inferolateral trunk (ILT) varied along the horizontal segment of the intracavernous ICA. On imaging studies the ICA curvature correlated with the kyphotic degree of the skull and similarity of the ICA curvature between sides. The safety margin for preventing iatrogenic intracavernous nerve injury during surgical exploration or transarterial embolization of vascular lesions around the MHT is high with redundant ICAs. In contrast, a transvenous endovascular approach via the inferior petrosal sinus may be too distant to reach the MHT when ICAs are redundant. Approaching lesions of the inferolateral trunk may be the same regardless of ICA type.
PMCID: PMC3023332  PMID: 21358996
Abducens nerve; carotid-cavernous fistula; cavernous sinus anatomy; internal carotid artery; sympathetic nerve
15.  Comparative Analysis of Extensions of Transbasal Approaches: Effect on Access to Midline and Paramedian Structures 
Skull Base  2009;19(6):387-399.
We sought to quantitate the effect of extensions of transbasal approaches (TBAs) on midline and paramedian targets of the cranial base. Eight silicone-injected cadaveric heads were dissected with extensions of TBA level I removal of the orbital bar. Objective measures were the comparisons of the accessibility of midline and paramedian targets with progressive dissections by level II detachment of the medial canthal ligaments and removal of the nasal bone and by level III removal of the lateral orbital walls with lateral orbital retraction. Mean areas of freedom increased for most targets with progressive bone removal. For midline targets, the most effective freedom increment was at the pituitary gland (level II: 28.8%, p = 0.05; level III: 107.1%, p < 0.001). For paramedian targets, the best freedom increment was for the foramen rotundum (level II: 56.4%; level III: 134.5%, all p < 0.001). Extensions of the TBA can increase the surgical corridor to midline and paramedian structures, especially for pituitary and maxillary regions. Level II exposure offers no clear benefit for most targets except the foramen rotundum. With level III exposure, all targets are effectively exposed compared with levels I and II.
PMCID: PMC2793888  PMID: 20436840
Clivus; cranial base surgery; craniofacial resection; quantitative analysis; transbasal approach
16.  Proposed Classification for the Transbasal Approach and Its Modifications 
Skull Base  2008;18(1):29-47.
The transbasal approach offers extradural exposure of the anterior midline skull base transcranially. It can be used to treat a variety of conditions, including trauma, craniofacial deformity, and tumors. This approach has been modified to enhance basal access. This article reviews the principle differences among modifications to the transbasal approach and introduces a new classification scheme. The rationale is to offer a uniform nomenclature to facilitate discussion of these approaches, their indications, and related issues.
PMCID: PMC2435472  PMID: 18592024
Frontal fossa; skull base; subcranial; subfrontal; transbasal
17.  [No title available] 
Skull Base  2003;13(3):183.
PMCID: PMC1131849
18.  Medulloblastoma Presenting with Tentorial “Dural-Tail” Sign 
Skull base surgery  1998;8(4):233-236.
To the best of our knowledge, the association of a medulloblastoma with a “dural-tail” sign has not been previously reported. A 24-year-old male developed severe headaches and right-sided dysmetria that worsened over 1 month. Magnetic resonance (MR) imaging of the brain demonstrated a heterogeneously enhancing lesion in the posterior fossa. The lesion appeared to be tentortally-based and exhibited a characteristic “dural-tail” sign, which is considered pathognothonic for meningioma. Cerebellar tonsil ectopia and hydrocephalus were also present. The presumptive diagnosis of tentorial meningioma was made. The lesion was resected by a posterior fossa approach. At surgery, the appearance of the tumor was inconsistent with the diagnosis of meningioma, and histopathologic evaluation yielded the diagnosis of medulloblastonia. This case and the literature demonstrate that malignant tumors can present with the characteristic MR imaging appearance of a meningioma. This possibility must be considered when treatment is planned, especially if a nonoperative course is favored.
PMCID: PMC1656697  PMID: 17171073
19.  Internal Carotid Artery Sacrifice for Radical Resection of Skull Base Tumors 
Skull base surgery  1996;6(2):119-123.
When dealing with skull base tumors that encase the internal carotid artery (ICA), the surgeon must decide between ICA preservation and incomplete tumor resection, or radical resection with ICA sacrifice. In our experience with more than 300 anterior skull base tumors, the ICA was sacrificed in only 10 patients. These tumors were malignant, except for one meningioma that occluded the ICA and produced translent ischemic symptoms. All patients had the ICA resected with the tumor, and all patients underwent revascularization (cervical ICA-MCA saphenous bypass, n = 4; cervical-to-supraclinoid bypass, n = 1; petrous-to-supraclinoid bypass, n = 3; bonnet bypass, n = 2). This small patient series reflects our practice of preserving the ICA whenever possible. We recommend preserving the ICA with benign tumors because they do not invade the artery, or do so only to a limited extent. In addition, similar rates of tumor recurrence are seen after aggressive resection with or without ICA sacrifice. In contrast, we recommend radical tumor resection and sacrifice of the ICA with malignant tumors because they directly threaten the integrity of the ICA and the patient's survival. The ICA should not be considered a limitation to radical tumor resection because the ICA can be reconstructed safely with an appropriate bypass procedure.
PMCID: PMC1656574  PMID: 17170986
20.  Combined Approach for Lesions Involving the Cerebellopontine Angle and Skull Base 
Skull base surgery  1991;1(4):226-234.
This article presents a series of 30 patients who underwent a combination of the subtemporal and posterior fossa approaches for exposure of lesions in the clivus or medial petrous region. This combined supra- and infratentorial approach is divided into three variations with progressively greater petrous bone resection to increase exposure of the clivus and medial petrous region. The approach has been divided into petrous bone resection with preservation of hearing (retrolabyrinthine), greater petrous bone resection with sacrifice of hearing (translabyrinthine), and finally maximum petrous drilling with sacrifice of hearing along with transposition of the facial nerve (transcochlear). Ninety-three percent of the cases returned to their premorbid occupations.
PMCID: PMC1656336  PMID: 17170840

Results 1-20 (20)