Publications by authors named "Angela Downes"

10 Publications

  • Page 1 of 1

Functioning Pituitary Adenoma with Xanthogranulomatous Features: Review of Literature and Case Report.

J Neurol Surg B Skull Base 2019 Oct 21;80(5):449-457. Epub 2018 Nov 21.

University of Colorado, Aurora, Colorado, United States.

 We present a patient with a prolactin-secreting adenoma with extensive secondary, noninfectious, xanthogranulomatous changes due to remote intratumoral bleeding and provide a literature review of xanthogranulomas (XGs) of the sellar region with emphasis on prolactinomas with xanthogranulomatous features.  Case report, with PubMed search of cases of sellar XG, focusing on neuroimaging and surgical approach.  A 35-year-old male was found to have a large sellar/suprasellar calcified/cystic mass. Endoscopic transsphenoidal approach for extradural resection was performed and diagnosis made. Review generated 31 patients with the diagnosis of sellar XG. In a minority (6 patients), the underlying lesion for the XG was a pituitary adenoma. Headache was the most common presenting symptom and panhypopituitarism the most common endocrinological abnormality. Examples of hyperprolactinemia associated with sellar XG are also uncommon and due to stalk effect. Neuroimaging of XG on T1-weighted magnetic resonance imaging (MRIs) showed 18 cases (56.3%) were hyperintense, 1 case (3.13%) was isointense, 4 (12.5%) had mixed-signal intensity, and 2 (6.25%) were hypointense. On T2-weighted MRIs, five lesions (15.6%) were hyperintense, three (9.38%) were isointense, nine (28.1%) were heterogeneous, and nine (28.1%) were hypointense. Only one case (3.1%) had calcifications on computed tomography scan similar to ours. In 14 cases (43.7%), the lesions enhanced with contrast administration on MRI.  Prolactinomas with secondary xanthogranulomatous change represent a rare cause of XG of the sella. With no radiological or clinical signs specific for XG of the sellar region, preoperative diagnosis can be challenging, if not impossible.
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http://dx.doi.org/10.1055/s-0038-1675232DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6748846PMC
October 2019

The potential value of probabilistic tractography-based for MR-guided focused ultrasound thalamotomy for essential tremor.

Neuroimage Clin 2018 12;17:1019-1027. Epub 2017 Dec 12.

Department of Neurosurgery David Geffen School of Medicine, UCLA, Los Angeles, CA, USA; Brain Research Institute David Geffen School of Medicine, UCLA, Los Angeles, CA, USA.

Magnetic Resonance-guided Focused UltraSound (MRgFUS) offers an incisionless approach to treat essential tremor (ET). Due to lack of evident internal anatomy on traditional structural imaging, indirect targeting must still be used to localize the lesion. Here, we investigate the potential predictive value of probabilistic tractography guided thalamic targeting by defining how tractography-defined targets, lesion size and location, and clinical outcomes interrelate. MR imaging and clinical outcomes from 12 ET patients that underwent MRgFUS thalamotomy in a pilot study at the University of Virginia were evaluated in this analysis. FSL was used to evaluate each patient's voxel-wise thalamic connectivity with FreeSurfer generated pre- and post-central gyrus targets, to generate thalamic target maps. Using Receiver Operating Characteristic curves, the overlap between these thalamic target maps and the MRgFUS lesion was systematically evaluated relative to clinical outcome. To further define the connectivity characteristics of effective MRgFUS thalamotomy lesions, we evaluated whole brain probabilistic tractography of lesions (using post-treatment imaging to define the lesion pre-treatment diffusion tensor MRI). The structural connectivity difference was explored between subjects with the best clinical outcome relative to all others. Ten of twelve patients presented high percentage of overlapping between connectivity-based thalamic segmentation maps and lesion area. The improvement of clinical score was predicted (AUC: 0.80) using the volume of intersection between the thalamic target (precentral gyrus) map and MRgFUS induced lesion as feature. The main structural differences between those with different magnitudes of response were observed in connectivity to the pre- and post-central gyri and brainstem/cerebellum. MRgFUS thalamotomy lesions characterized by strong structural connectivity to precentral gyrus demonstrated better responses in a cohort of patients treated with MRgFUS for ET. The intersection between lesion and thalamic-connectivity maps to motor - sensory targets proved to be effective in predicting the response to the therapy. These imaging techniques can be used to increase the efficacy and consistency of outcomes with MRgFUS and potentially shorten treatment times by identifying optimal targets in advance of treatment.
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http://dx.doi.org/10.1016/j.nicl.2017.12.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5842733PMC
January 2019

Acute Ischemic Stroke During Deep Brain Stimulation Surgery of Globus Pallidus Internus: Report of 5 Cases.

Oper Neurosurg (Hagerstown) 2016 12;12(4):383-390

Department of Neurosurgery, University of California, Los Angeles, Los Angeles, California.

Background: Cerebrovascular accident (CVA) is a potentially devastating complication of deep brain stimulation (DBS) surgery. Although there are substantial data reporting the incidence and cause of hemorrhagic CVA, reports of acute ischemic infarctions during DBS implantation surgery are rare.

Objective: To present a series of 5 patients who experienced clinically significant ischemic CVA during microelectrode-guided globus pallidus internus (GPi) DBS, and evaluate the potential risk factors and mechanisms.

Methods: A retrospective analysis of GPi DBS surgeries performed between June 2010 and February 2015 at UCLA Medical Center and June 2010 and February 2014 at Cedars-Sinai Medical Centers was performed to identify stroke risk factors. Statistical analysis was performed, comparing the stroke group with all patients undergoing GPi DBS.

Results: All 5 patients developed acute onset of lethargy, dysarthria, and contralateral facial and/or hemibody weakness intraoperatively. Computed tomographic scans in all cases were negative for hemorrhage. Magnetic resonance images obtained in 3 patients revealed infarction in the posterior limb of the internal capsule. During the time period analyzed, a total of 234 GPi leads were placed in 129 patients, yielding a 2.14% rate of ischemic stroke per lead. No statistically significant risk factors were identified in the stroke group. Given the variability of symptom onset during surgery, the mechanism is not clear, but it could be related to compression, compromise, or vasospasm of lenticulostriate arteries and/or anterior choroidal branches near the GPi target.

Conclusion: Ischemic stroke in GPi DBS is a significant complication for clinicians to be aware of and discuss with their patients preoperatively.
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http://dx.doi.org/10.1227/NEU.0000000000001359DOI Listing
December 2016

Unilateral Tailored Fronto-Orbital Approach for Giant Olfactory Groove Meningiomas: Technical Nuances.

World Neurosurg 2015 Oct 16;84(4):1166-73. Epub 2015 May 16.

Department of Neurosurgery, University of Colorado School of Medicine, Aurora, Colorado, USA. Electronic address:

Objective: Giant olfactory groove meningiomas (maximum diameter ≥6 cm) remain a surgical challenge. Historically, extensive anterior and antero-lateral approaches have been the primary approaches for removal of such large tumors with limitations and morbidity pertaining to each approach. Herein, the authors describe a minimally invasive, unilateral, tailored fronto-orbital approach for resection of these complex lesions with an emphasis on preservation of the anterior cerebral arteries and olfactory nerves.

Methods: A 4-stage approach using neuronavigation is performed: 1) predefined corridor, 2) identification of the ipsilateral anterior cerebral artery, 3) postdefined corridor, and 4) tumor base. The details of this approach are described below in a stepwise fashion and supplemented by a sample of 3 cases utilizing this technique.

Results: In the 3 representative cases in which this technique was used, gross total resection was achieved without injury to any of the adjacent neurovascular structures. Significant sellar extension can be resected through a second stage endoscopic endonasal approach.

Conclusion: Giant olfactory groove meningiomas (≥6 cm) can be safely and completely resected with this 4-stage, unilateral fronto-orbital technique. Furthermore, early identification and preservation of the adjacent critical neurovascular structures can be achieved. This technique avoids the inherent limitations and morbidity associated with the more classic pterional and bifrontal approaches respectively while minimizing normal tissue disruption.
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http://dx.doi.org/10.1016/j.wneu.2015.05.011DOI Listing
October 2015

Bucket and straw technique to facilitate passage of a ventriculoperitoneal shunt through the distal tunneling sheath.

J Neurosurg Pediatr 2014 Dec 10;14(6):662-4. Epub 2014 Oct 10.

Department of Neurosurgery, Morsani College of Medicine, University of South Florida, Tampa;

Placement of a ventriculoperitoneal shunt (VPS) is a procedure comprising many small steps. Difficulties and delays can arise when passing the distal shunt tubing down the distal tunneling sheath during surgery. The authors of this report describe a simple technique for quickly passing the distal catheter of a VPS through the tunneler sheath, whereby the sheath is used as a fluid tube to allow the distal catheter to be drawn through the fluid tube under suction pressure. The plastic sheath that surrounds the shunt tunneler device is used as a fluid tube, or "straw," with the proximal aperture submerged into a bucket of sterile irrigation liquid containing the distal catheter. Suction pressure is placed against the distal aperture of the tunneler, and the shunt catheter is quickly drawn through the sheath. No special equipment is required. In time trials, the bucket and straw technique took an average of 0.43 seconds, whereas traditional passage methods took 32.3 seconds. The "bucket and straw" method for passing distal shunt tubing through the tunneler sheath is a technique that increases surgical efficiency and reduces manual contact with shunt hardware.
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http://dx.doi.org/10.3171/2014.9.PEDS14171DOI Listing
December 2014

Alzheimer's disease: The role for neurosurgery.

Surg Neurol Int 2014 5;5(Suppl 8):S385-90. Epub 2014 Sep 5.

Department of Neurosurgery, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA ; HCor Neuroscience, São Paulo, Brazil.

Dementia, most commonly caused by Alzheimer's disease (AD), affects approximately 35 million people worldwide, with the incidence expected to increase as the population ages. After decades of investigation, AD is now understood to be a complex disease that affects behavior and cognition through several mechanisms: Disrupted neuronal communication, abnormal regional tissue metabolism, and impaired cellular repair. Existing therapies have demonstrated limited efficacy, which has spurred the search for specific disease markers and predictors as well as innovative therapeutic options. Deep brain stimulation (DBS) of the memory circuits is one such option, with early studies suggesting that modulation of neural activity in these networks may improve cognitive function. Encapsulated cell biodelivery (ECB) is a device that delivers nerve growth factor to the cholinergic basal forebrain to potentially improve cognitive decline in AD patients. This review discusses the pathogenesis of AD, novel neuroimaging and biochemical markers, and the emerging role for neurosurgical applications such as DBS and ECB.
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http://dx.doi.org/10.4103/2152-7806.140191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4173304PMC
October 2014

Advanced neuroimaging techniques for central neuromodulation.

Neurosurg Clin N Am 2014 Jan 5;25(1):173-85. Epub 2013 Oct 5.

Department of Neurosurgery, Morsani College of Medicine, University of South Florida, 2 Tampa General Circle, 7th Floor, Tampa, FL 33606, USA. Electronic address:

Deep brain stimulation an effective treatment of many neurologic conditions such as Parkinson disease, essential tremor, dystonia, and obsessive-compulsive disorder. Structural and functional neuroimaging studies provide the opportunity to visualize the dysfunctional nodes and networks underlying neurologic and psychiatric disease, and to thereby realize new targets for neuromodulation as well as personalize current therapy. This article reviews contemporary advances in neuroimaging in the basic sciences and how they can be applied to redirect and propel functional neurosurgery toward a goal of functional localization of targets with individualized maps and identification of novel targets for other neuropsychiatric diseases.
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http://dx.doi.org/10.1016/j.nec.2013.08.012DOI Listing
January 2014

The frontotemporal-orbitozygomatic approach: reconstructive technique and outcome.

Acta Neurochir (Wien) 2012 Jul 11;154(7):1275-83. Epub 2012 May 11.

Department of Neurosurgery, University of South Florida, Tampa, FL, USA.

Background: The frontotemporal-orbitozygomatic (FTOZ) approach, also known as "the workhorse of skull base surgery," has captured the interest of many researchers throughout the years. Most of the studies published have focused on the surgical technique and the gained exposure. However, few studies have described reconstructive techniques or functional and cosmetic outcomes. The goal of this study was to describe the surgical reconstruction after the FTOZ approach and analyze the functional and cosmetic outcomes.

Methods: Seventy-five consecutive patients who had undergone FTOZ craniotomy for different reasons were selected. The same surgical (one-piece FTOZ) and reconstructive techniques were applied in all patients. The functional outcome was measured by complications related to the surgical approach: retro-orbital pain, exophthalmos, enophthalmos, ocular movement restriction, cranial nerve injuries, pseudomeningocele (PMC) and secondary surgeries required to attain a reconstructive closure. The cosmetic outcome was evaluated by analyzing the satisfaction of the patients and their families. Questionnaires were conducted later in the postoperative period. A statistical analysis of the data obtained from the charts and questions was performed.

Results: Of the 75 patients studied, 59 had no complications whatsoever. Ocular movement restriction was found in two patients (2.4 %). Cranial nerve injury was documented in seven patients (8.5 %). One patient (1.2 %) underwent surgical repair of a cerebrospinal fluid (CSF) leak from the initial surgery. Two patients (2.4 %) developed delayed postoperative pseudomenigocele. One patient (1.2 %) developed intraparenchymal hemorrhage (IPH). Full responses to the questionnaires were collected from 28 patients giving an overall response rate of 34 %. Overall, 22 patients (78.5 %) were satisfied with the cosmetic outcome of surgery.

Conclusion: The reconstruction after FTOZ approach is as important as the performance of the surgical technique. Attention to anatomical details and the stepwise reconstruction are a prerequisite to the successful preservation of function and cosmesis. In our series, the orbitozygomatic osteotomy did not increase surgical complications or alter cosmetic outcomes.
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http://dx.doi.org/10.1007/s00701-012-1370-9DOI Listing
July 2012

Life without the vein of Galen: Clinical and radiographic sequelae.

Clin Anat 2011 Sep 24;24(6):776-85. Epub 2011 Mar 24.

Department of Neurosurgery, University of South Florida, Tampa, Florida, USA.

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.
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http://dx.doi.org/10.1002/ca.21176DOI Listing
September 2011

Intraoperative neurophysiological monitoring in vestibular schwannoma surgery: advances and clinical implications.

Neurosurg Focus 2009 Oct;27(4):E9

Department of Neurosurgery, University of South Florida, Tampa, Florida 33606, USA.

Object: Intraoperative neurophysiological monitoring has become an integral part of vestibular schwannoma surgery. The aim of this article was to review the different techniques of intraoperative neurophysiological monitoring in vestibular schwannoma surgery, identify the clinical impact of certain pathognomonic patterns on postoperative outcomes of facial nerve function and hearing preservation, and highlight the role of postoperative medications in improving delayed cranial nerve dysfunction in the different reported series.

Methods: The authors performed a review of the literature regarding intraoperative monitoring in acoustic/vestibular schwannoma surgery. The different clinical series representing different monitoring techniques were reviewed. All the data from clinical series were analyzed in a comprehensive and comparative model.

Results: Intraoperative brainstem auditory evoked potential monitoring, direct cochlear nerve action potential monitoring, and facial nerve electromyography are the main tools used to assess the functional integrity of an anatomically intact cranial nerve. The identification of pathognomonic brainstem auditory evoked potential and electromyography patterns has been correlated with postoperative functional outcome. Recently, perioperative administration of intravenous hydroxyethyl starch and nimodipine as vasoactive and neuroprotective agents was shown to improve vestibular schwannoma functional outcome in few reported studies.

Conclusions: Recent advances in electrophysiological technology have considerably contributed to improvement in functional outcome of vestibular neuroma surgery in terms of hearing preservation and facial nerve paresis. Perioperative intravenous nimodipine and hydroxyethyl starch may be valuable additions to surgery.
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http://dx.doi.org/10.3171/2009.8.FOCUS09144DOI Listing
October 2009
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