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1.
Epilepsy Behav ; 155: 109669, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38663142

RESUMO

The purpose of this study was to systematically examine three different surgical approaches in treating left medial temporal lobe epilepsy (mTLE) (viz., subtemporal selective amygdalohippocampectomy [subSAH], stereotactic laser amygdalohippocampotomy [SLAH], and anterior temporal lobectomy [ATL]), to determine which procedures are most favorable in terms of visual confrontation naming and seizure relief outcome. This was a retrospective study of 33 adults with intractable mTLE who underwent left temporal lobe surgery at three different epilepsy surgery centers who also underwent pre-, and at least 6-month post-surgical neuropsychological testing. Measures included the Boston Naming Test (BNT) and the Engel Epilepsy Surgery Outcome Scale. Fisher's exact tests revealed a statistically significant decline in naming in ATLs compared to SLAHs, but no other significant group differences. 82% of ATL and 36% of subSAH patients showed a significant naming decline whereas no SLAH patient (0%) had a significant naming decline. Significant postoperative naming improvement was seen in 36% of SLAH patients in contrast to 9% improvement in subSAH patients and 0% improvement in ATLs. Finally, there were no statistically significant differences between surgical approaches with regard to seizure freedom outcome, although there was a trend towards better seizure relief outcome among the ATL patients. Results support a possible benefit of SLAH in preserving visual confrontation naming after left TLE surgery. While result interpretation is limited by the small sample size, findings suggest outcome is likely to differ by surgical approach, and that further research on cognitive and seizure freedom outcomes is needed to inform patients and providers of potential risks and benefits with each.


Assuntos
Lobectomia Temporal Anterior , Epilepsia do Lobo Temporal , Testes Neuropsicológicos , Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Resultado do Tratamento , Epilepsia do Lobo Temporal/cirurgia , Estudos Retrospectivos , Lobectomia Temporal Anterior/métodos , Lobectomia Temporal Anterior/efeitos adversos , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Adulto Jovem , Convulsões/cirurgia , Procedimentos Neurocirúrgicos/métodos , Lobo Temporal/cirurgia
2.
Neuro Oncol ; 26(2): 348-361, 2024 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-37715730

RESUMO

BACKGROUND: Recurrent brain tumors are the leading cause of cancer death in children. Indoleamine 2,3-dioxygenase (IDO) is a targetable metabolic checkpoint that, in preclinical models, inhibits anti-tumor immunity following chemotherapy. METHODS: We conducted a phase I trial (NCT02502708) of the oral IDO-pathway inhibitor indoximod in children with recurrent brain tumors or newly diagnosed diffuse intrinsic pontine glioma (DIPG). Separate dose-finding arms were performed for indoximod in combination with oral temozolomide (200 mg/m2/day x 5 days in 28-day cycles), or with palliative conformal radiation. Blood samples were collected at baseline and monthly for single-cell RNA-sequencing with paired single-cell T cell receptor sequencing. RESULTS: Eighty-one patients were treated with indoximod-based combination therapy. Median follow-up was 52 months (range 39-77 months). Maximum tolerated dose was not reached, and the pediatric dose of indoximod was determined as 19.2 mg/kg/dose, twice daily. Median overall survival was 13.3 months (n = 68, range 0.2-62.7) for all patients with recurrent disease and 14.4 months (n = 13, range 4.7-29.7) for DIPG. The subset of n = 26 patients who showed evidence of objective response (even a partial or mixed response) had over 3-fold longer median OS (25.2 months, range 5.4-61.9, p = 0.006) compared to n = 37 nonresponders (7.3 months, range 0.2-62.7). Four patients remain free of active disease longer than 36 months. Single-cell sequencing confirmed emergence of new circulating CD8 T cell clonotypes with late effector phenotype. CONCLUSIONS: Indoximod was well tolerated and could be safely combined with chemotherapy and radiation. Encouraging preliminary evidence of efficacy supports advancing to Phase II/III trials for pediatric brain tumors.


Assuntos
Neoplasias Encefálicas , Neoplasias do Tronco Encefálico , Humanos , Criança , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/patologia , Temozolomida , Triptofano , Fatores Imunológicos , Imunoterapia , Neoplasias do Tronco Encefálico/patologia
3.
World Neurosurg ; 132: 347-355, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31520766

RESUMO

BACKGROUND: Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a recently recognized epileptogenic neuroepithelial tumor. Despite its distinctiveness, its polymorphous histology and the nature of its oligodendrocyte-like cells remain unclear. CASE DESCRIPTION: A 30-year-old, right-handed man was diagnosed with intractable epilepsy since 22 years of age. Magnetic resonance imaging revealed T2 signal hyperintensity and corresponding T1 signal hypointensity within the subcortical white matter of the right middle temporal gyrus. Positron emission tomography scan demonstrated hypometabolism in the right anterior temporal region. Electroencephalography and stereo-electroencephalography monitoring localized seizures to the right temporal lobe, allowing the patient to undergo right temporal lobectomy. Histologic sections demonstrated cortical dysplasia, white matter heterotopia, and hippocampal reactive gliosis without neuronal loss. Interestingly, an approximately 6-mm subcortical neoplasm was identified in the temporal lobectomy. It was composed of well-differentiated oligodendroglial-like cells but exhibited mild-to-moderate nuclear variability and pleomorphism, and mild infiltration into the overlying cortex without perineuronal satellitosis. No mitotic activity, microvascular proliferation, or necrosis was identified, and Ki-67 labeling index was less than 1%. The tumor was diffusely CD34 positive with moderate glial fibrillary acidic protein and retained ATRX staining, and demonstrated the presence of the BRAF V600E mutation. The tumor was negative for reticulin condensation, synaptophysin, SMI31, neuronal nuclei immunostains, and both the IDH1 mutation and 1p19q codeletion. Overall histologic findings were most consistent with PLNTY. CONCLUSIONS: The correct diagnosis of PLNTY and its distinction from closely resembling low-grade neuroepithelial tumors is important. We hope our proposed diagnostic features will aid in its proper diagnosis and management.


Assuntos
Neoplasias Encefálicas/genética , Neoplasias Encefálicas/cirurgia , Neoplasias Neuroepiteliomatosas/genética , Neoplasias Neuroepiteliomatosas/cirurgia , Adulto , Lobectomia Temporal Anterior/métodos , Biomarcadores Tumorais/análise , Neoplasias Encefálicas/diagnóstico por imagem , Diagnóstico Diferencial , Epilepsia Resistente a Medicamentos/complicações , Epilepsia Resistente a Medicamentos/diagnóstico por imagem , Epilepsia Resistente a Medicamentos/cirurgia , Eletroencefalografia , Humanos , Imuno-Histoquímica , Imageamento por Ressonância Magnética , Masculino , Neoplasias Neuroepiteliomatosas/diagnóstico por imagem , Tomografia por Emissão de Pósitrons
4.
J Neurosurg ; 127(6): 1426-1435, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28298020

RESUMO

Although image-based human stereotaxis began with Spiegel and Wycis in 1947, the major principles of radiographic stereotaxis were formulated 50 years earlier by the French scientific photographer Gaston Contremoulins. In 1897, frustrated by the high morbidity of bullet extraction from the brain, the Parisian surgeon Charles Rémy asked Contremoulins to devise a method for bullet localization using the then new technology of x-rays. In doing so, Contremoulins conceived of many of the modern principles of stereotaxis, including the use of a reference frame, radiopaque fiducials for registration, images to locate the target in relation to the frame, phantom devices to locate the target in relation to the fiducial marks, and the use of an adjustable pointer to guide the surgical approach. Contremoulins' ideas did not emerge from science or medicine, but instead were inspired by his training in the fine arts. Had he been a physician instead of an artist, he might have never discovered his extraordinary methods. Contremoulins' "compass" and its variants enjoyed great success during World War I, but were abandoned by 1920 for simpler methods. Although Contremoulins was one of the most eminent radiographers in France, he was not a physician, and his personality was uncompromising. By 1940, both he and his methods were forgotten. It was not until 1988 that he was rediscovered by Moreau while reviewing the history of French radiology, and chronicled by Mornet in his extensive biography. The authors examine Contremoulins' stereotactic methods in historical context, describe the details of his devices, relate his discoveries to his training in the fine arts, and discuss how his prescient formulation of stereotaxis was forgotten for more than half a century.


Assuntos
Radiologia/história , Técnicas Estereotáxicas/história , História do Século XX , Humanos
5.
World Neurosurg ; 99: 118-121, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27931947

RESUMO

BACKGROUND: Exposure of the carotid sheath during vagus nerve stimulator (VNS) implantation is usually straightforward but can be difficult for patients with a large body habitus. In addition, the exposure must be done with care if the surgeon wants to keep the vagus nerve in situ without using retractors that might impair access. OBJECTIVE: We describe the use of the omohyoid muscle as a landmark for the jugular vein and report how transection of the omohyoid can facilitate rapid and wide exposure of the carotid sheath. METHODS: We review the records of 59 consecutive patients undergoing VNS implantation from 2009-2015 and describe our technique incorporating omohyoid transection. We also summarize complications such as postoperative hoarseness, cough, dysphagia, or wound issues. RESULTS: Forty-two of the 59 patients (29 adults and 13 children) underwent omohyoid transection during implantation. In all cases, the carotid sheath and jugular vein were immediately visible after transection. One patient developed permanent hoarseness and coughing due to left vocal cord paresis, requiring further surgery. This result was most likely due to manipulation of the vagus nerve rather than division of the omohyoid muscle. CONCLUSION: Omohyoid transection provides excellent exposure of the carotid sheath during VNS implantation.


Assuntos
Neuroestimuladores Implantáveis , Músculos do Pescoço/cirurgia , Procedimentos Neurocirúrgicos/métodos , Implantação de Prótese/métodos , Nervo Vago/cirurgia , Adulto , Criança , Feminino , Humanos , Masculino , Estudos Retrospectivos , Resultado do Tratamento
7.
Surg Neurol Int ; 7(Suppl 1): S20-2, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26862454

RESUMO

BACKGROUND: To demonstrate that the diagnosis of an intracranial subdural hematoma should be considered for patients presenting with acute or delayed symptoms of intracranial pathology following resection of a spinal tumor. CASE DESCRIPTION: We present a case of a 57-year-old woman found to have a chronic subdural hematoma 1 month following resection of a thoracic extramedullary ependymoma. Evacuation of the hematoma through a burr hole relieved the presenting symptoms and signs. Resolution of the hematoma was confirmed with a computed tomography (CT) scan. CONCLUSION: Headache and other symptoms not referable to spinal pathology should be regarded as a warning sign of an intracranial subdural hematoma, and a CT scan of the head should be obtained. The mechanism of the development of the hematoma may be related to the leakage of cerebrospinal fluid with subsequent intracranial hypotension leading to an expanding subdural space and hemorrhage.

8.
World Neurosurg ; 84(2): 591.e1-5, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25841757

RESUMO

BACKGROUND: Despite the best efforts to ensure stereotactic precision, deep brain stimulation (DBS) electrodes can wander from their intended position after implantation. We report a case of downward electrode migration 10 years following successful implantation in a patient with Parkinson disease. METHODS: A 53-year-old man with Parkinson disease underwent bilateral implantation of DBS electrodes connected to a subclavicular 2-channel pulse generator. The generator was replaced 7 years later, and a computed tomography (CT) scan confirmed the correct position of both leads. The patient developed a gradual worsening affecting his right side 3 years later, 10 years after the original implantation. A CT scan revealed displacement of the left electrode inferiorly into the pons. The new CT scans and the CT scans obtained immediately after the implantation were merged within a stereotactic planning workstation (Brainlab). RESULTS: Comparing the CT scans, the distal end of the electrode was in the same position, the proximal tip being significantly more inferior. The size and configuration of the coiled portions of the electrode had not changed. At implantation, the length was 27.7 cm; after 10 years, the length was 30.6 cm. CONCLUSIONS: These data suggests that the electrode had been stretched into its new position rather than pushed. Clinicians evaluating patients with a delayed worsening should be aware of this rare event.


Assuntos
Estimulação Encefálica Profunda/instrumentação , Eletrodos Implantados , Migração de Corpo Estranho/etiologia , Doença de Parkinson/cirurgia , Ponte , Complicações Pós-Operatórias/etiologia , Núcleo Subtalâmico/cirurgia , Desenho de Equipamento , Migração de Corpo Estranho/diagnóstico por imagem , Migração de Corpo Estranho/cirurgia , Reação a Corpo Estranho/diagnóstico por imagem , Reação a Corpo Estranho/etiologia , Reação a Corpo Estranho/cirurgia , Granuloma de Corpo Estranho/diagnóstico por imagem , Granuloma de Corpo Estranho/etiologia , Granuloma de Corpo Estranho/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Doença de Parkinson/diagnóstico por imagem , Ponte/diagnóstico por imagem , Ponte/cirurgia , Complicações Pós-Operatórias/diagnóstico por imagem , Complicações Pós-Operatórias/cirurgia , Reoperação , Núcleo Subtalâmico/diagnóstico por imagem , Tomografia Computadorizada por Raios X
9.
J Neurol Surg A Cent Eur Neurosurg ; 74 Suppl 1: e149-54, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23427033

RESUMO

Choroid plexus carcinomas (CPCs) are rare epithelial central nervous system tumors. CPC occurs mainly in infants and young children, comprising ≈ 1 to 4% of all pediatric brain neoplasms. There is very limited information available regarding tumor biology and CPC treatment due to its rarity. There have been various case reports and meta-analyses of reported cases with CPC. Surgical resection is often challenging but remains a well-established treatment option. Chemotherapy is often reserved for recurrent or refractory cases, but the goal of treatment is usually palliative. We present a case of recurrent, adult CPC with disseminated leptomeningeal involvement treated with salvage chemotherapy including high-dose ifosfamide, carboplatin, and etoposide; once a remission was achieved, this response was consolidated with a syngeneic stem cell (bone marrow) transplant after a preparative regimen of high-dose chemotherapy with carboplatin, etoposide, and thiotepa. Although the patient tolerated the transplant well and remained disease-free for 12 months, she subsequently succumbed to relapsed disease 18 months posttransplant. We believe that this is the first report of using syngeneic stem cell transplant in CPC to consolidate a remission achieved by salvage chemotherapy.


Assuntos
Antineoplásicos/uso terapêutico , Transplante de Medula Óssea/métodos , Carcinoma/terapia , Neoplasias do Plexo Corióideo/terapia , Transplante de Células-Tronco/métodos , Transplante Isogênico/métodos , Neoplasias Cerebelares/patologia , Ângulo Cerebelopontino/patologia , Quimiorradioterapia , Intervalo Livre de Doença , Evolução Fatal , Feminino , Perda Auditiva/etiologia , Humanos , Imageamento por Ressonância Magnética , Neuroma Acústico/patologia , Cuidados Paliativos , Convulsões/etiologia , Gêmeos , Adulto Jovem
10.
J Neurol Surg A Cent Eur Neurosurg ; 73(5): 320-3, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22847067

RESUMO

BACKGROUND: Centers implanting deep brain stimulator (DBS) electrodes on different days often protect the first electrode tip with a protective cap, tunnel it under the scalp, and connect it to the generator at a later procedure. If magnetic resonance imaging (MRI) is used for planning during the second implantation, MRI artifacts from the protective cap could potentially corrupt the stereotactic coordinates. The importance of this problem may increase if emerging MRI safety data lead to more frequent use of MRI for these purposes. OBJECTIVE: To describe an MRI artifact arising from the use of the standard protective DBS cap that corrupts stereotactic planning and to describe a way to avoid the artifact. METHODS: After noting the artifact during a staged DBS procedure, a nonmetallic silastic sleeve contained in the existing DBS implantation kit was used in nine subsequent patients. Two caps with standard metallic screws were also tested with MRI phantoms. RESULTS: The silastic sleeve protected the DBS electrode but did not produce MRI artifact. The phantom studies demonstrated significant artifact from caps containing screws. CONCLUSION: A silastic sleeve provides adequate protection of the DBS electrode during staged implantation and avoids the MRI artifact associated with protective caps with screws.


Assuntos
Artefatos , Estimulação Encefálica Profunda/instrumentação , Eletrodos Implantados/efeitos adversos , Imageamento por Ressonância Magnética , Estimulação Encefálica Profunda/métodos , Dimetilpolisiloxanos , Feminino , Humanos , Doença de Parkinson/terapia , Técnicas Estereotáxicas/instrumentação , Resultado do Tratamento , Adulto Jovem
11.
J Neurosurg ; 110(2): 263-73, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19012484

RESUMO

OBJECT: The authors previously developed an optical stereotactic probe employing near-infrared (NIR) spectroscopy to provide intraoperative localization by distinguishing gray matter from white matter. In the current study they extend and further validate this technology. METHODS: Near-infrared probes were inserted 203 times during 138 procedures for movement disorders. Detailed validation with postoperative imaging was obtained for 121 of these procedures and with microelectrode recording (MER) for 30 procedures. Probes were constructed to interrogate tissue perpendicular to the probe path and to incorporate hollow channels for microelectrodes, deep brain stimulation (DBS) electrodes, and other payloads. RESULTS: The NIR data were highly correlated to imaging and MER recordings for thalamic targets. The NIR data were highly sensitive but less specific relative to imaging for subthalamic targets, confirming the ability to detect the subthalamic nucleus and to provide warnings of inaccurate localization. The difference between the NIR- and MER-detected midpoints of the subthalamic nucleus along the chosen tracks was 1.1 +/- 1.2 mm (SD). Data obtained during insertion and withdrawal of the NIR probe suggested that DBS electrodes may push their targets ahead of their paths. There was one symptomatic morbidity. Detailed NIR data could be obtained from a 7-cm track in less than 10 minutes. CONCLUSIONS: The NIR probe is a straightforward, quick, and robust tool for intraoperative localization during functional neurosurgery. Potential future applications include localization of targets for epilepsy and psychiatric disorders, and incorporation of NIR guidance into probes designed to convey various payloads.


Assuntos
Estimulação Encefálica Profunda/instrumentação , Distonia/terapia , Tremor Essencial/terapia , Microcirurgia/instrumentação , Doença de Parkinson/terapia , Espectroscopia de Luz Próxima ao Infravermelho/instrumentação , Técnicas Estereotáxicas/instrumentação , Instrumentos Cirúrgicos , Tremor/terapia , Mapeamento Encefálico/instrumentação , Dominância Cerebral/fisiologia , Distonia/fisiopatologia , Desenho de Equipamento , Tremor Essencial/fisiopatologia , Globo Pálido/patologia , Globo Pálido/fisiopatologia , Humanos , Imageamento por Ressonância Magnética , Microeletrodos , Doença de Parkinson/fisiopatologia , Complicações Pós-Operatórias/diagnóstico , Complicações Pós-Operatórias/patologia , Núcleo Subtalâmico/patologia , Núcleo Subtalâmico/fisiopatologia , Tálamo/patologia , Tálamo/fisiopatologia , Tomografia Computadorizada por Raios X , Tremor/fisiopatologia
12.
Proc (Bayl Univ Med Cent) ; 21(3): 255-7, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18628973

RESUMO

Dural arteriovenous fistulae are rare lesions composed of abnormal connections between meningeal arteries and the dural sinuses or lepto-meningeal veins. Treatment is challenging because of the small size and wide distribution of the myriad sites of fistulous connection. We present a case of a dural arteriovenous fistula presenting with visual deterioration, pulsatile tinnitus, and intracranial hypertension that was successfully treated with a multidisciplinary approach combining angiographic, surgical, and radiosurgical intervention. This is one of the largest of these formidable lesions treated in this fashion that has been reported.

13.
Neurosurgery ; 62(4): 939-44; discussion 944-6, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18496200

RESUMO

OBJECTIVE: Socioeconomic changes have imposed many administrative demands on neurosurgeons, including managing facilities such as the intensive care unit without absolute authority and maintaining referrals, marketing in an increasingly competitive environment, effecting change within stubborn hospital systems, negotiating fair contracts with insurance companies, using financial statements to make financial decisions, managing small groups under new rules of human resources, navigating a Byzantine system of reimbursement, and assessing entrepreneurial opportunities. A set of new tools and skills has been developed by the business community in response to similar problems that may be of use to neurosurgeons. These advances are reviewed in a neurosurgical context, and routes to business training for the neurosurgeon are discussed. METHODS: Recent advances in business are discussed with a focus on their relevance to neurosurgical practice. Current neurosurgical interest in business training and training opportunities for neurosurgeons are presented. RESULTS: Interest in business training within the neurosurgery community is keen, and advances in the field of business may be helpful in addressing the new tasks faced by neurosurgeons. CONCLUSION: New tools from advances in business are available which have been invaluable to corporations and may be helpful to neurosurgeons wanting to improve efficiency and maintain competitive advantage. Business training is available to neurosurgeons through a variety of routes.


Assuntos
Comércio/educação , Currículo , Educação Médica/organização & administração , Neurocirurgia/educação , Estudos de Viabilidade , Texas
14.
J Neurosurg ; 109 Suppl: 25-33, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19123885

RESUMO

OBJECT: Gamma Knife (GK) treatments are typically delivered in 1 day with little opportunity to test different planning strategies. The authors demonstrate 2 methods for imposing GK coordinate systems upon imaging datasets without frame attachment to allow leisurely preprocedural planning, and discuss potential applications. METHODS: A "virtual framing" is constructed by coregistering a CT scan of a Leksell frame with a patient dataset using the GammaPlan (Multiview) module. Equations for skull radii are derived by approximating the skull as an ellipsoid. No proprietary software other than that of the GK system is required. In a second method, images of fiducial markers are directly superimposed on the patient dataset. Validation of the first method was achieved by comparing the lengths of 75 line segments and 60 single shot diameters measured in the virtual coordinates with those measured in real coordinates. In addition to preplanning, 2 applications are discussed. The first is the use of GK software to aid radiosurgical planning for other devices. The second is the use of virtual framing to enhance automatic optimization algorithms. RESULTS: Mean (+/- standard deviation) and root-mean-square differences in lengths were 0.18 +/- 0.32 and 0.37 mm. Mean and root-mean-square differences in diameters of single-shot plans were 0.01 +/- 0.18 and 0.18 mm. CONCLUSIONS: Virtual framing allows exploration of radiosurgical planning strategies prior to the day of treatment using only the GK software. Other applications include enhancement of radiosurgical planning for other systems and enhancement of optimization algorithms.


Assuntos
Cordoma/cirurgia , Fossa Craniana Posterior , Radiocirurgia/instrumentação , Neoplasias da Base do Crânio/cirurgia , Cirurgia Assistida por Computador/métodos , Algoritmos , Cordoma/diagnóstico por imagem , Cordoma/patologia , Estudos de Coortes , Estudos de Viabilidade , Feminino , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Radiocirurgia/métodos , Reprodutibilidade dos Testes , Estudos Retrospectivos , Neoplasias da Base do Crânio/diagnóstico por imagem , Neoplasias da Base do Crânio/patologia , Cirurgia Assistida por Computador/instrumentação , Tomografia Computadorizada por Raios X
15.
Appl Opt ; 46(23): 5552-61, 2007 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-17694099

RESUMO

An optical probe used to localize human brain tissues in vivo has been reported previously. It was able to sense the underlying tissue structure with an optical interrogation field, termed as "look ahead distance" (LAD). A new side-firing probe has been designed with its optical window along its side. We have defined the optical interrogation field of the new side probe as "look aside distance" (LASD). The purpose of this study is to understand the dependence of the LAD and LASD on the optical properties of tissue, the light source intensity, and the integration time of the detector, using experimental and computational methods. The results show that a decrease in light intensity does decrease the LAD and LASD and that an increase in integration time of detection may not necessarily improve the depths of LAD and LASD. Furthermore, Monte Carlo simulation results suggest that the LAD/LASD decreases with an increase in reduced scattering coefficient to a point, after which the LAD/LASD remains constant. We expect that an optical interrogation field of a tip or side probe is approximately 1-2 mm in white matter and 2-3.5 mm in gray matter. These conclusions will help us optimally manipulate the parameter settings during surgery and determine the spatial resolution of the probe.


Assuntos
Óptica e Fotônica , Calibragem , Simulação por Computador , Desenho de Equipamento , Luz , Método de Monte Carlo , Imagens de Fantasmas , Fótons , Espalhamento de Radiação , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Fatores de Tempo , Tomografia Óptica/métodos
16.
J Neurosurg ; 107(1 Suppl): 5-10, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17644914

RESUMO

OBJECT: The object of this study was to identify prognostic factors for survival among children with recurrent medulloblastoma. METHODS: Postprogression survival and patient, tumor, and treatment factors were examined in 46 cases of recurrent medulloblastoma (mean age of patients at diagnosis 6.5 years, mean age at progression 8.4 years). Differences were calculated by Kaplan-Meier log-rank analysis. Multivariate analysis was performed using the Cox proportional hazard model. RESULTS: The probability of 5-year survival was 26.3%. Forty-one patients received salvage therapy and five patients received hospice care only. Log-rank analysis showed an association between prolonged patient survival and recurrence limited to the primary site (p = 0.008), initial therapy including the Pediatric Oncology Group (POG) regimen for the treatment of brain tumors in infants ("Baby POG;" p = 0.037), and treatment with radiation therapy (RT) following initial progression (p = 0.015). Cox regression analysis showed a significant association between prolonged survival and only one variable--tumor recurrence restricted to the primary site (p = 0.037). There was no significant association between prolonged survival and any other variables, including patient sex, age at progression, interval from tumor diagnosis to progression, initial tumor stage, and salvage treatment with chemotherapy. Subgroup analysis revealed that site of tumor progression was also prognostic for survival among the subgroup of patients older than 3 years of age at diagnosis who were initially treated with RT and chemotherapy (p = 0.017, log-rank test). CONCLUSIONS: Some children with recurrent medulloblastoma will be long-term survivors, and certain features are associated with likelihood of survival. Patients whose tumors recur at only the primary tumor site have an increased chance of prolonged survival.


Assuntos
Neoplasias Cerebelares/mortalidade , Meduloblastoma/mortalidade , Recidiva Local de Neoplasia/mortalidade , Adolescente , Neoplasias Cerebelares/tratamento farmacológico , Neoplasias Cerebelares/radioterapia , Neoplasias Cerebelares/cirurgia , Quimioterapia Adjuvante , Criança , Pré-Escolar , Progressão da Doença , Feminino , Seguimentos , Humanos , Lactente , Estimativa de Kaplan-Meier , Masculino , Meduloblastoma/tratamento farmacológico , Meduloblastoma/radioterapia , Meduloblastoma/cirurgia , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/radioterapia , Recidiva Local de Neoplasia/cirurgia , Prognóstico , Radioterapia Adjuvante , Terapia de Salvação
17.
Neurol Res ; 29(6): 563-8, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17535568

RESUMO

OBJECTIVE: Radiosurgery is frequently offered to patients with progressive malignant brain tumors if radiation therapy or chemotherapy fails to provide local control. The use of single-shot regimens, however, is limited by the risk of complications when the tumor is large, surrounded by edema or has been pre-treated with radiation. Hypofractionation may confer safety but has not been tested for these difficult tumors. We report the results of hypofractionation as an alternative option in a small cohort of progressive malignant brain tumors. METHODS: Hypofractionated CyberKnife radiotherapy was chosen for 18 progressive malignant brain tumors (six high-grade gliomas and 12 metastatic lesions) in 15 patients because of size, previous treatment with radiation or surrounding edema. The mean dose was 21 +/- 4 Gy and the number of fractions was 5 +/- 0.6. The volume of each tumor at treatment was compared with the volume at follow-up. RESULTS: Thirteen of the 18 tumors (72%) showed a volume decrease. The average volume change was a decrease of 16 +/- 58% (median: 20%) with a follow-up of 180 +/- 121 days (median: 172 days). Toxicity occurred in only one patient, with symptoms improving on steroids. DISCUSSION: Progression of malignant brain tumors not ideal for single-shot radiosurgery can be arrested or reversed, at least for short periods, with minimal toxicity using hypofractionated radiotherapy. Longer studies will be needed to assess durability of this response in these difficult tumors.


Assuntos
Neoplasias Encefálicas/cirurgia , Radiocirurgia/métodos , Radioterapia Assistida por Computador/métodos , Técnicas Estereotáxicas , Adulto , Fracionamento da Dose de Radiação , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Dosagem Radioterapêutica , Estudos Retrospectivos , Terapia de Salvação , Taxa de Sobrevida , Resultado do Tratamento
18.
J Physiol ; 579(Pt 3): 799-810, 2007 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-17185344

RESUMO

Exposure to microgravity alters the distribution of body fluids and the degree of distension of cranial blood vessels, and these changes in turn may provoke structural remodelling and altered cerebral autoregulation. Impaired cerebral autoregulation has been documented following weightlessness simulated by head-down bed rest in humans, and is proposed as a mechanism responsible for postspaceflight orthostatic intolerance. In this study, we tested the hypothesis that spaceflight impairs cerebral autoregulation. We studied six astronauts approximately 72 and 23 days before, after 1 and 2 weeks in space (n = 4), on landing day, and 1 day after the 16 day Neurolab space shuttle mission. Beat-by-beat changes of photoplethysmographic mean arterial pressure and transcranial Doppler middle cerebral artery blood flow velocity were measured during 5 min of spontaneous breathing, 30 mmHg lower body suction to simulate standing in space, and 10 min of 60 deg passive upright tilt on Earth. Dynamic cerebral autoregulation was quantified by analysis of the transfer function between spontaneous changes of mean arterial pressure and cerebral artery blood flow velocity, in the very low- (0.02-0.07 Hz), low- (0.07-0.20 Hz) and high-frequency (0.20-0.35 Hz) ranges. Resting middle cerebral artery blood flow velocity did not change significantly from preflight values during or after spaceflight. Reductions of cerebral blood flow velocity during lower body suction were significant before spaceflight (P < 0.05, repeated measures ANOVA), but not during or after spaceflight. Absolute and percentage reductions of mean (+/- s.e.m.) cerebral blood flow velocity after 10 min upright tilt were smaller after than before spaceflight (absolute, -4 +/- 3 cm s(-1) after versus -14 +/- 3 cm s(-1) before, P = 0.001; and percentage, -8.0 +/- 4.8% after versus -24.8 +/- 4.4% before, P < 0.05), consistent with improved rather than impaired cerebral blood flow regulation. Low-frequency gain decreased significantly (P < 0.05) by 26, 23 and 27% after 1 and 2 weeks in space and on landing day, respectively, compared with preflight values, which is also consistent with improved autoregulation. We conclude that human cerebral autoregulation is preserved, and possibly even improved, by short-duration spaceflight.


Assuntos
Adaptação Fisiológica/fisiologia , Encéfalo/irrigação sanguínea , Encéfalo/fisiologia , Homeostase/fisiologia , Voo Espacial , Adulto , Astronautas , Velocidade do Fluxo Sanguíneo/fisiologia , Pressão Sanguínea/fisiologia , Circulação Cerebrovascular/fisiologia , Humanos , Hipotensão Ortostática/fisiopatologia , Masculino , Estresse Fisiológico/fisiopatologia , Ausência de Peso
19.
Proc (Bayl Univ Med Cent) ; 18(4): 311-9; discussion 319-20, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16252020

RESUMO

Radiosurgery is defined as the use of highly focused beams of radiation to ablate a pathologic target, thus achieving a surgical objective by noninvasive means. Recent advances have allowed a wide variety of intracranial lesions to be effectively treated with radiosurgery, and radiosurgical treatment has been accepted as a standard part of the neurosurgical armamentarium. The advent of frameless radiosurgery now permits radiosurgical treatment to all parts of the body and is being actively explored by many centers. This article reviews some of the modern tools for radiosurgical treatment and discusses the current clinical practice of radiosurgery.

20.
J Neurosurg ; 102(3): 571-5, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15796399

RESUMO

Direct observation of the subthalamic nucleus (STN) is not always possible, and physicians at many centers rely on indirect methods that relate the position of the STN to more easily recognized structures such as the red nucleus (RN). In this paper the authors describe an indirect method of viewing the STN based on the anatomy depicted on sagittal magnetic resonance (MR) images. A review of sagittal slices appearing in standard stereotactic atlases showed that the STN lies within the angle formed by the descending internal capsule (IC) and the substantia nigra (SN). The authors' technique consists of marking the location of the STN in this nigrocapsular angle on each sagittal MR image between the RN and the lateral border of the brainstem, and transferring these points to axial MR images to build a locus of points used to describe the STN. A point is chosen in the center of this locus as the stereotactic target. Two hundred eighty-two sagittal images obtained from 71 MR imaging studies performed in 29 patients by using a fast-spin echo inversion-recovery technique were examined for the presence of the STN, the SN, and the IC. The descending IC could be detected in 97% of the slices, the SN in 95% of the slices, and the STN in 73% of the slices. This indirect method involving sagittal anatomy can be used to refine localization of the STN.


Assuntos
Imageamento por Ressonância Magnética/métodos , Núcleo Subtalâmico/anatomia & histologia , Humanos
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