16 results on '"Ranalli NJ"'
Search Results
2. Historical Perspectives on the Management of Craniosynostosis.
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Holley TJ, Ranalli NJ, and Steinberg B
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- Humans, Craniofacial Abnormalities surgery, Craniosynostoses surgery, Plastic Surgery Procedures
- Abstract
The history of craniofacial surgery is one of many fundamental advances by monumental figures. Although craniosynostosis has been known to exist for multiple centuries, modern management has evolved over roughly the last century. An overview of early history, early scientific exploration, the advancement of surgical treatment of craniofacial deformities and the current state of craniosynostosis management is discussed. To fully appreciate the evolution of craniosynostosis surgery, one must understand the gradual advancements that have brought the specialty to this modern era., Competing Interests: Disclosure None of the authors have any commercial or financial conflicts of interest or funding sources., (Copyright © 2022 Elsevier Inc. All rights reserved.)
- Published
- 2022
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3. Modern Therapy for Spinal and Paraspinal Ewing Sarcoma: An Update of the University of Florida Experience.
- Author
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Indelicato DJ, Vega RBM, Viviers E, Morris CG, Bradfield SM, Ranalli NJ, and Bradley JA
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- Child, Humans, Relative Biological Effectiveness, Retrospective Studies, Spine pathology, Treatment Outcome, Proton Therapy adverse effects, Sarcoma, Ewing radiotherapy
- Abstract
Purpose: In 2010, we published a comprehensive review of our institutional outcomes about treating children with spinal and paraspinal Ewing sarcoma using photon therapy. Multimodality therapy was associated with fair disease control but also with serious toxicity, including a 37% rate of grade 3 or greater toxicity. We therefore sought to assess our more recent experience about treating children with more modern technology and treatment regimens., Methods and Materials: Between 2010 and 2021, 32 pediatric patients with nonmetastatic spinal and paraspinal Ewing sarcoma were treated at University of Florida and enrolled in a retrospective outcome study. Median age at diagnosis was 9.8 years (range, 2.1-21.8 years). Within the cervical, thoracic, and lumbar spine regions, 3, 22, and 7 tumors arose, respectively. Median maximum tumor diameter was 5 cm (range, 3-19 cm). At diagnosis, 28 of 32 patients had motor, bowel, or bladder deficits. Chemotherapy was delivered according to contemporary North American and European interval-compressed regimens. Before radiation therapy, 14 patients underwent gross total resection, whereas 18 underwent a biopsy or subtotal resection with cord decompression. All patients were treated with proton therapy; 6 with hardware stabilization also received a component of intensity modulated photon therapy. Median prescription dose was 50.4 gray relative biological effectiveness (GyRBE; range, 45-55.8 GyRBE). Median maximum dose to the spinal cord was 50.2 GyRBE (range, 0-54.9 GyRBE)., Results: With a median follow-up of 4.1 years (range, 0.7-9.4 years), the 5-year local control, progression-free survival, and overall survival rates were 92%, 79%, and 85%, respectively. Ten of 30 living patients have residual motor, bowel, or bladder deficits. Overall, 22% of patients experienced Common Terminology Criteria for Adverse Events grade 3 late toxicity related to multimodality treatment: kyphosis (n = 4), esophagitis (n = 2), and chronic kidney disease (n = 1). No patients developed grade 4 or greater toxicity, new neurologic deficits, or second malignancy., Conclusions: Modern treatment advances may offer an improved therapeutic ratio for pediatric patients with spinal and paraspinal Ewing sarcoma. With appropriate management, most patients can be cured with recovery of long-term neurologic function and modest side effects., (Copyright © 2022 Elsevier Inc. All rights reserved.)
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- 2022
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4. Prioritizing Pediatricians' Neurosurgical Education: Results From a National Survey of Primary Care Pediatricians.
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Aldana PR, Beier AD, Ranalli NJ, Sisk B, and Ragheb JR
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- Adult, Child, Female, Humans, Internship and Residency statistics & numerical data, Male, Middle Aged, Pediatrics methods, Practice Patterns, Physicians' statistics & numerical data, Surveys and Questionnaires, United States, Internship and Residency methods, Nervous System Diseases diagnosis, Nervous System Diseases therapy, Neurosurgery education, Pediatrics education, Primary Health Care methods
- Abstract
Introduction . We surveyed nonretired American Academy of Pediatrics-member US pediatricians regarding common neurosurgical conditions, identifying specific areas of focus in education. Methods . Data were acquired via self-administered electronic questionnaire. Results . Of 505 total respondents, 56% reported neurology was not a required residency rotation, and 86% had diagnosed craniosynostosis, plagiocephaly, or macrocephaly. Craniosynostosis can mostly be diagnosed by physical examination alone, but almost 50% reported relying on skull X-rays. Fifty-four percent reported diagnosing ocular surface disease (OSD; with 15% to 40% not screening an infant despite well-established cutaneous markers). Seventy-four screened OSD in a patient with sacral dimple. Ninety-seven percent reported treating concussion, but nearly 25% did not manage these patients alone. Two out of 3 patients indicated head injury as most important for continuing education. Conclusion . Improved education for craniosynostosis, OSD, head injury, and concussion management are important for earlier diagnosis, management, and referral of some disorders, while decreasing resource utilization in others. These results should be used when considering pediatrician educational programs.
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- 2020
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5. Outcomes Following Proton Therapy for Pediatric Low-Grade Glioma.
- Author
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Indelicato DJ, Rotondo RL, Uezono H, Sandler ES, Aldana PR, Ranalli NJ, Beier AD, Morris CG, and Bradley JA
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- Adolescent, Adrenal Cortex Hormones therapeutic use, Analysis of Variance, Astrocytoma drug therapy, Astrocytoma mortality, Astrocytoma pathology, Astrocytoma radiotherapy, Brain Neoplasms drug therapy, Brain Neoplasms mortality, Brain Neoplasms pathology, Child, Child, Preschool, Confidence Intervals, Female, Glioma drug therapy, Glioma mortality, Glioma pathology, Humans, Male, Progression-Free Survival, Prospective Studies, Radiation Injuries drug therapy, Radiotherapy Dosage, Survival Rate, Treatment Outcome, Young Adult, Brain Neoplasms radiotherapy, Glioma radiotherapy, Proton Therapy adverse effects
- Abstract
Purpose: Dosimetric studies show that proton therapy can reduce the low/intermediate radiation dose to uninvolved tissue in children with low-grade glioma (LGG). For this reason, LGG is the fourth most common pediatric tumor treated with proton therapy, yet clinical outcome data on efficacy and toxicity are limited., Methods and Materials: We reviewed the medical records of 174 children (≤21 years old) with nonmetastatic LGG enrolled on a prospective protocol and treated with proton therapy between 2007 and 2017. We assessed clinical outcomes and toxicity and analyzed patient, tumor, and treatment-related variables., Results: The median age was 10.2 years (range, 2-21). Fifty-eight percent of tumors were World Health Organization grade 1 and 30% were grade 2; 12% were diagnosed on imaging characteristics alone. The most common histology was pilocytic astrocytoma (47%). The most common tumor subsites were diencephalon/optic pathway (52%), caudal brainstem (16%), and cerebellum (13%). Forty-two percent received chemotherapy before radiation therapy. The median follow-up was 4.4 years. The 5-year actuarial rates of local control, progression-free survival, and overall survival were 85% (95% confidence interval [CI], 78%-90%), 84% (95% CI, 77%-89%), and 92% (95% CI, 85%-95%), respectively. On univariate analysis, brainstem/spinal cord tumor location (62% vs 90% elsewhere) and dose <54 GyRBE (67% vs 91% for 54 GyRBE) were associated with inferior local control (P < .01 for both). Twenty-two patients (12.6%) experienced acute nausea or vomiting requiring ondansetron; 2 patients (1.1%) required corticosteroids. Serious toxicities (4% of patients) included brainstem necrosis requiring corticosteroids (n = 2), symptomatic vasculopathy (n = 2), radiation retinopathy (n = 1), epilepsy (n = 1), and death from radiation-induced high-grade glioma (n = 1). Thirty-nine patients (22%) developed new-onset central hormone deficiency. Pseudoprogression was observed in 32.1%., Conclusions: Compared with modern photon series, proton therapy reduces the radiation dose to developing brain tissue, diminishing acute toxicities without compromising disease control., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2019
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6. Outcomes following proton therapy for pediatric ependymoma.
- Author
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Indelicato DJ, Bradley JA, Rotondo RL, Nanda RH, Logie N, Sandler ES, Aldana PR, Ranalli NJ, Beier AD, Morris CG, and Mendenhall NP
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- Adolescent, Brain Neoplasms mortality, Brain Neoplasms surgery, Child, Child, Preschool, Combined Modality Therapy, Disease-Free Survival, Ependymoma mortality, Ependymoma surgery, Female, Humans, Infant, Kaplan-Meier Estimate, Male, Neurosurgical Procedures, Proton Therapy adverse effects, Proton Therapy mortality, Treatment Outcome, Young Adult, Brain Neoplasms radiotherapy, Ependymoma radiotherapy, Proton Therapy methods
- Abstract
Background: Proton therapy can reduce the low and intermediate radiation dose to uninvolved brain tissue in children with intracranial ependymomas, which may improve functional outcomes and reduce second malignancies in survivors. Accordingly, ependymoma has become the most common pediatric tumor treated with proton therapy, yet data on efficacy and toxicity are limited., Material and Methods: Between June 2007 and February 2017, 179 children (≤21 years old) with nonmetastatic grade II/III intracranial ependymoma received proton therapy at our institution. Median age, 3.5 years (range, 0.7-21); 58% were male. Most (66%) tumors were in the posterior fossa and classified as WHO grade III (67%). 27% underwent multiple operations to maximize the extent of resection; ultimately 85% had a gross total or near total tumor resection before radiotherapy. 33% received preradiation chemotherapy. Median radiation dose in children ≤3 years old, 54 Gy(RBE). Most (>90%) children over 3 years old received 59.4 Gy(RBE). Patient and treatment variables were assessed for correlation with disease control., Results: Median follow-up, 3.2 years. 3-year local control, progression-free survival, and overall survival rates were 85%, 76%, and 90%, respectively. First site of progression was local, metastatic, or simultaneous in 14, 17 and 6 patients, respectively. On multivariate analysis, subtotal resection was associated with inferior local control (67% vs. 88%; p ≤ .01) and progression-free survival (59% vs. 79%; p < .05). Male sex was associated with inferior progression-free (67% vs. 87%; p< .05) and overall survival (84% vs. 99%; p < .01). The 3-year CTCAE grade 2 + brainstem toxicity rate was 5.5% (95% CI: 2.9-10.2), including 1 grade 5 toxicity., Conclusions: This series of proton therapy for pediatric intracranial ependymoma demonstrates disease control comparable to photon series without unexpected toxicity. Subtotal resection and male sex were associated with inferior disease control. Additional follow-up to quantify the expected reductions in late toxicity with proton therapy is ongoing.
- Published
- 2018
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7. Primary delayed onset craniosynostosis in a child demonstrated by serial computed tomography imaging.
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Guevara C, Wallender A, Steinberg B, and Ranalli NJ
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- Child, Preschool, Cranial Sutures surgery, Craniosynostoses surgery, Craniotomy methods, Humans, Infant, Male, Cranial Sutures diagnostic imaging, Craniosynostoses diagnostic imaging, Tomography, X-Ray Computed
- Abstract
Primary delayed onset craniosynostosis is a rarely reported phenomenon. The unique case of a 2-year-old boy who had computed tomography (CT) scans performed 20 months apart demonstrating the post-gestational development of sagittal suture craniosynostosis is presented. The otherwise healthy male initially presented to the emergency department at age 7 months with soft tissue swelling over his left parietal region secondary to a fall. A CT scan revealed a possible left parietal skull fracture without intracranial pathology and patent cranial sutures with a normocephalic calvarial configuration. Twenty months later, his paediatrician referred the boy to the craniofacial service for evaluation of progressive dolichocephaly. A new CT scan showed complete fusion of the sagittal suture with resultant biparietal narrowing, frontal bossing, and occipital prominence. The patient subsequently underwent uncomplicated frontoparietal craniotomy with calvarial vault reconstruction. Prior reports in the literature of cases of non-syndromic primary delayed onset craniosynostosis all lack 'pre-synostosis' CT imaging that proves post-birth patency of the cranial sutures. This case report documents CT demonstrating true primary delayed onset craniosynostosis., (Copyright © 2016 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)
- Published
- 2016
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8. Baclofen pump catheter leakage after migration of the abdominal catheter in a pediatric patient with spasticity.
- Author
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Dastgir A, Ranalli NJ, MacGregor TL, and Aldana PR
- Subjects
- Abdomen, Adolescent, Cerebral Palsy etiology, Humans, Male, Muscle Spasticity diagnosis, Baclofen administration & dosage, Catheters, Indwelling adverse effects, Cerebral Palsy complications, Foreign-Body Migration, Infusion Pumps, Implantable, Injections, Spinal, Muscle Relaxants, Central administration & dosage, Muscle Spasticity drug therapy
- Abstract
The authors report an unusual case of intrathecal baclofen withdrawal due to the perforation and subsequent leakage of a baclofen pump catheter in a patient with spastic cerebral palsy. A 15-year-old boy underwent an uncomplicated placement of an intrathecal baclofen pump for the treatment of spasticity due to cerebral palsy. After excellent control of symptoms for 3 years, the patient presented to the emergency department with increasing tremors following a refill of his baclofen pump. Initial evaluation consisted of radiographs of the pump and catheter, which appeared normal, and a successful aspiration of CSF from the pump's side port. A CT dye study revealed a portion of the catheter directly overlying the refill port and extravasation of radiopaque dye into the subfascial pocket anterior to the pump. During subsequent revision surgery, a small puncture hole in the catheter was seen to be leaking the drug. The likely cause of the puncture was an inadvertent perforation of the catheter by a needle during the refilling of the pump. This case report highlights a unique complication in a patient with an intrathecal baclofen pump. Physicians caring for these patients should be aware of this rare yet potential complication in patients presenting with baclofen withdrawal symptoms.
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- 2015
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9. Delayed synostoses of uninvolved sutures after surgical treatment of nonsyndromic craniosynostosis.
- Author
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Yarbrough CK, Smyth MD, Holekamp TF, Ranalli NJ, Huang AH, Patel KB, Kane AA, and Woo AS
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- Adolescent, Child, Child, Preschool, Endoscopy, Female, Follow-Up Studies, Head Protective Devices, Humans, Imaging, Three-Dimensional, Infant, Infant, Newborn, Male, Postoperative Care, Postoperative Complications diagnosis, Postoperative Complications surgery, Recurrence, Reoperation, Sutures, Tomography, X-Ray Computed, Cranial Sutures surgery, Craniosynostoses surgery, Postoperative Complications etiology, Plastic Surgery Procedures methods
- Abstract
Background: Craniosynostosis causes significant cranial deformity in the pediatric population. Open and endoscopic-assisted surgeries have led to increasingly successful management of this condition. Following surgical reconstruction, subsequent development of postnatal synostosis of previously patent sutures have been described and noted to be most frequently associated with multisuture synostosis patients with syndromic diagnoses. Very rarely, postsurgical new sutural fusion has been identified in nonsyndromic patients who initially present with isolated single-suture synostosis. The purpose of this study was to evaluate the incidence of new synostosis among patients who had undergone craniosynostosis reconstruction with either the open or endoscopic technique., Methods: Patients undergoing open and endoscopic surgery for nonsyndromic craniosynostosis were reviewed. Preoperative and postoperative imaging and clinical information were reviewed, and cases showing progressive cranial deformity were identified., Results: Three (2.1%) of 145 patients undergoing open craniosynostosis surgery and 2 (1.7%) of 121 patients undergoing endoscopic surgery developed delayed fusion of an additional suture during follow-up. This was identified at a median of 16.4 months after initial surgery in the open group and 15.25 months after surgery in the endoscopic group. In patients undergoing open surgery, each patient developed new sagittal synostosis after initial presentation of coronal synostosis in 1 patient and metopic synostosis in 2 patients. In patients undergoing endoscopic surgery, each patient developed new coronal synostosis after sagittal repair., Conclusions: Management of craniosynostosis has evolved over time with increasing availability of effective and safe treatments. During long-term follow-up, a small number of patients may develop premature closure of a different suture that did not undergo surgical manipulation. In our case, series, we identified 3 patients undergoing open surgery and 2 patients undergoing endoscopic surgery for nonsyndromic, single-suture craniosynostosis. This finding supports the necessity of long-term clinical follow-up and the utility of delayed imaging when clinical suspicion indicates.
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- 2014
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10. Direct cardiac ventriculoatrial shunt: technical note.
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Heuer GG, Ranalli NJ, Pisapia J, Storm PB, Gruber PJ, and Sutton LN
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- Adult, Heart diagnostic imaging, Heart Atria diagnostic imaging, Heart Atria surgery, Humans, Hydrocephalus diagnostic imaging, Male, Thoracotomy methods, Tomography, X-Ray Computed, Cardiac Surgical Procedures methods, Cerebrospinal Fluid Shunts methods, Hydrocephalus surgery
- Abstract
There are a number of choices for placement of the distal catheter during ventricular shunting for hydrocephalic patients. In very rare instances, patients with multiple revisions can no longer have their shunt placed in the routine locations. We describe the placement of the distal catheter into the atrium through direct cardiac access, a technique described decades ago but rarely needed in clinical practice. This can be a useful location in the limited number of patients who have exhausted other more routine locations., (Copyright © 2012 S. Karger AG, Basel.)
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- 2012
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11. Hemangiomas of the brachial plexus: a case series.
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Ranalli NJ, Huang JH, Lee EB, Zhang PJ, Siegelman ES, and Zager EL
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- Adolescent, Adult, Aged, Angiography, Digital Subtraction, Biopsy, Brachial Plexus pathology, Brachial Plexus surgery, Brachial Plexus Neuropathies therapy, Diagnosis, Differential, Diagnostic Imaging, Electromyography, Embolization, Therapeutic, Female, Hemangioma therapy, Humans, Middle Aged, Nerve Sheath Neoplasms diagnosis, Neurosurgical Procedures methods, Preoperative Care methods, Retrospective Studies, Treatment Outcome, Young Adult, Brachial Plexus physiopathology, Brachial Plexus Neuropathies diagnosis, Brachial Plexus Neuropathies physiopathology, Hemangioma diagnosis, Hemangioma physiopathology
- Abstract
Objective: Hemangiomas of the brachial plexus are very rare, and there has not been a collection of multiple cases published in the literature to date. Extraneural brachial plexus hemangiomas typically present with similar signs and symptoms as nerve sheath tumors, including pain, paresthesia, and occasionally weakness, in addition to nonspecific imaging findings, making their diagnosis difficult. Exploratory surgery can lead to significant bleeding and nerve injury when a hemangioma or an associated aneurysm is encountered intraoperatively. We present 5 cases of extraneural hemangiomas causing brachial plexopathy, including pre-, intra-, and postoperative decision making, with an emphasis on diagnostic and management issues as well as outcomes., Methods: A retrospective review was performed of 5 patients who underwent surgery at a university teaching hospital between 1995 and 2007 for exploration of brachial plexus lesions that were confirmed to be hemangiomas at pathological examination., Results: All 5 patients presented with findings on history, physical examination, imaging, and electromyography suggesting a diagnosis of nerve sheath tumor. Two patients had biopsies (1 needle, 1 open), both of which were nondiagnostic. Three patients underwent digital subtraction angiography with successful preoperative embolization. Each patient had a complete or a radical subtotal tumor resection, and all were intact neurologically after surgical resection. Pathological evaluation identified 3 venous hemangiomas, 1 hemangioma with arteriovenous malformation features, and 1 Masson hemangioma associated with a large aneurysm., Conclusion: Extraneural hemangiomas of the brachial plexus are very rare, but a high index of suspicion and appropriate preoperative evaluation, including angiography with the option for embolization, can result in decreased intraoperative hemorrhage and better patient outcomes.
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- 2009
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12. Thalamic deep brain stimulation for midbrain tremor secondary to cystic degeneration of the brainstem.
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Sanborn MR, Danish SF, Ranalli NJ, Grady MS, Jaggi JL, and Baltuch GH
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- Adult, Cysts complications, Cysts pathology, Humans, Magnetic Resonance Imaging, Male, Neurodegenerative Diseases complications, Neurodegenerative Diseases pathology, Tremor etiology, Brain Stem pathology, Deep Brain Stimulation, Tremor surgery, Tremor therapy, Ventral Thalamic Nuclei surgery
- Abstract
Objective: Tremor resulting from damage to midbrain structures is poorly understood and often difficult to treat. The authors report a case of cystic degeneration of the brainstem with resultant Holmes-like tremor which was successfully treated using a stimulating electrode placed in the contralateral ventralis intermedius nucleus (VIM) of the thalamus., Clinical Presentation: A 31-year-old man presented with a multilobulated, multiseptated lesion of the upper brainstem diagnosed after subacute onset of headaches. The patient subsequently developed an incapacitating left-upper-extremity tremor refractory to medical treatment., Intervention: The patient underwent implantation of a deep brain stimulator in the VIM with symptomatic and functional improvement., Conclusions: Deep brain stimulation is an effective and safe intervention for tremor of unusual etiology. Electrode placement should be based on an understanding of the structure-function relationships underlying the various and distinct types of tremor., ((c) 2009 S. Karger AG, Basel.)
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- 2009
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13. A novel neuroprosthetic interface with the peripheral nervous system using artificially engineered axonal tracts.
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Kameswaran N, Cullen DK, Pfister BJ, Ranalli NJ, Huang JH, Zager EL, and Smith DH
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- Animals, Humans, Guided Tissue Regeneration methods, Nerve Regeneration physiology, Peripheral Nervous System Diseases surgery, Tissue Engineering methods, User-Computer Interface
- Abstract
Objective: We have previously described a technique developed in our laboratory to create transplantable living axon tracts of several centimeters in length. In this paper, we describe how these engineered neural tissue constructs can be used to create a novel neuroelectrical interface with the regenerating peripheral nervous system, to potentially enable afferent and efferent communications with prosthetic devices., Methods: Using continuous mechanical tension, we have generated axon tracts of up to 10 cm in length, spanning two populations of neurons in vitro. We have now adapted this stretch-growth paradigm to include a mechanically compliant multi-electrode array that is attached to one of the neuron populations. Once the desired axon length has been reached, the neuroelectrode construct is completely embedded in a supportive hydrogel matrix and affixed to the transected sciatic nerve., Results: Building upon our previous work with peripheral nerve repair, we have designed our neural interface to ensure transplant stability and firm attachment to the electrode array substrate., Discussion: Our preliminary findings indicate that the interface not only maintains its orientation, but also is conducive to host nerve ingrowth. Our ongoing analysis seeks to characterize transplanted neuronal survival, synaptic integration, and functional connectivity. This research provides an opportunity to evaluate an entirely new approach in restoring motor and sensory functions of patients with peripheral nerve damage.
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- 2008
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14. Clinical problem-solving: brachial plexus closed injury and reconstruction.
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Ranalli NJ, Kline DG, McGarvey ML, Boulis NM, and Zager EL
- Subjects
- Adult, Humans, Male, Microsurgery methods, Nerve Transfer methods, Radiculopathy diagnosis, Radiculopathy etiology, Wounds, Nonpenetrating diagnosis, Wounds, Nonpenetrating etiology, Brachial Plexus injuries, Radiculopathy surgery, Wounds, Nonpenetrating surgery
- Abstract
Objective: Current management of severe brachial plexus injury has undergone recent modifications, and surgical options have expanded., Methods: The case of a man with a severe closed brachial plexus injury resulting from a motorcycle accident is presented. The patient is found to have upper root avulsions that deprive him of function in the proximal arm., Results: Pre-, intra-, and postoperative decision making is reviewed by an expert in peripheral nerve surgery. Attention is paid to both diagnosis and management. A brief review of the literature pertaining to these points follows., Conclusion: The recent expansion of surgical options for the management of severe brachial plexus injury has introduced significant controversy into this field.
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- 2008
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15. Food restriction affects the gonadotropin releasing hormone neuronal system of male prairie voles (Microtus ochrogaster).
- Author
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Kriegsfeld LJ, Ranalli NJ, Trasy AG, and Nelson RJ
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- Adipose Tissue metabolism, Animals, Brain cytology, Brain physiology, Cell Count, Cell Size, Frontal Lobe cytology, Frontal Lobe physiology, Hypothalamus, Anterior cytology, Hypothalamus, Anterior physiology, Male, Neurons cytology, Preoptic Area cytology, Septum Pellucidum cytology, Septum Pellucidum physiology, Time Factors, Arvicolinae physiology, Food Deprivation physiology, Gonadotropin-Releasing Hormone physiology, Neurons physiology
- Abstract
Individuals of species inhabiting temperate and boreal latitudes optimize the timing of energetically costly processes by curtailing nonessential energetically demanding processes when environmental conditions are not favourable. One proximate environmental variable used to fine-tune moment-to-moment changes in reproductive physiology and behaviour is food intake. The neuroendocrine mechanisms by which food restriction leads to the cessation of reproduction in seasonally breeding rodent species remain largely unspecified. The present study sought to determine the effects of extended food restriction on the gonadotropin releasing hormone (GnRH) neuronal system. Male prairie voles (Microtus ochrogaster) were either fed ad libitum or were exposed to either 1, 2 or 3 weeks of moderate (70% of daily mean) food restriction. In accordance with previous studies of food restriction, gross reproductive organ masses and body mass were unaffected by food deprivation. Although 1 week of food restriction did not result in alterations in the GnRH neuronal system, food restriction for 2 weeks was associated with increased GnRH-immunoreactive (GnRH-ir) neurone soma size. Three weeks of food restriction resulted in a pronounced increase in GnRH-ir neurone numbers, as well as an increase in fibre intensity in the main fibre pathway to the median eminence. Taken together, these findings suggest that extended food restriction leads to modifications in the GnRH neuronal system, providing a means for temporary cessation of reproduction without gross alterations in reproductive physiology. This transient change in the hypothalmo-pituitary-gonadal axis, without pronounced changes in reproductive organ morphology, likely provides a mechanism for the rapid reinitiation of breeding in nature when local conditions provide adequate food availability.
- Published
- 2001
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16. Photoperiod and temperature interact to affect the GnRH neuronal system of male prairie voles (Microtus ochrogaster).
- Author
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Kriegsfeld LJ, Ranalli NJ, Bober MA, and Nelson RJ
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- Animals, Arvicolinae, Body Weight, Epididymis anatomy & histology, Epididymis physiology, Hypothalamus, Anterior cytology, Immunohistochemistry, Male, Median Eminence cytology, Median Eminence physiology, Neurons cytology, Organ Size, Preoptic Area cytology, Seminal Vesicles anatomy & histology, Seminal Vesicles physiology, Temperature, Testis anatomy & histology, Testis physiology, Acclimatization physiology, Gonadotropin-Releasing Hormone physiology, Hypothalamus, Anterior physiology, Neurons physiology, Photoperiod, Preoptic Area physiology
- Abstract
Individuals of numerous species limit energy expenditure during winter by inhibiting reproduction and other nonessential functions. To time these adaptations appropriately with the annual cycle, animals rely on environmental cues that predict, well in advance, the onset of winter. The most commonly studied environmental factor that animals use to time reproduction is photoperiod. Rodents housed in short photoperiods in the laboratory or in naturally declining day lengths exhibit pronounced alterations in reproductive function concomitant with alterations in the hypothalamic gonadotropin-releasing hormone neuronal system. Because animals in their natural environment use factors in addition to photoperiod to time reproduction, the present study sought to determine the independent effects of photoperiod and temperature, as well as the interaction between these factors, on reproductive parameters and the GnRH neuronal system. Male prairie voles were housed in either long (LD 16:8) or short (LD 8:16) day lengths for 10 weeks. Animals in each photoperiod were further subdivided into groups housed in either mild (i.e., 20 degrees C) or low (i.e., 8 degrees C) temperatures. As shown with immunohistochemistry, voles that underwent gonadal regression in response to short photoperiods and long-day voles housed in low temperatures (and maintained large gonads) exhibit higher GnRH-immunoreactive (GnRH-ir) neuron numbers in the preoptic area/anterior hypothalamus (POA/AH) relative to all other groups. In addition, voles that underwent gonadal regression in response to both short days and low temperatures did not exhibit an increase in GnRH-ir neuron numbers compared to long-day, mild-temperature controls. These data suggest that photoperiod and temperature interact to influence reproductive function potentially by alterations of the GnRH neuronal system.
- Published
- 2000
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