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OBJECTIVE: To identify opportunities for discontinuing elective and nonemergency surgical cases in a regional surgical practice in response to coronavirus disease 2019 (COVID-19). PATIENTS AND METHODS: COVID-19 began to affect surgical practices across the United States in March 2020. On March 17, 2020, all elective and nonemergency surgical care was deferred to prepare the Mayo Clinic Health System sites in northwestern Wisconsin for an anticipated surge in patients with COVID-19. When the decision was made to reactivate the surgical practice, several major structural and operational changes were made to the regional surgical practice to optimize efficiencies. RESULTS: The structural and operational changes implemented during reactivation resulted in improved utilization of surgical resources including improvement in operating room (OR) block utilization, increased available OR time, and increased case volumes. CONCLUSION: Surgical and procedural leaders should consider a limited-time deferral of elective surgical cases to implement widespread OR efficiency strategies. The time selected for deferral of surgical cases should target a period of historically low surgical volume to minimize disruption to patient care and impact on overall OR functions.
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We present a case of an intramedullary melanotic schwannoma (IMS) of the thoracic spinal cord. To our knowledge, this is the seventh reported case of an IMS of the central nervous system. Schwannomas are benign nerve sheath tumors of neural crest origin composed entirely of well differentiated Schwann cells that typically occur in peripheral nerves. Both the intramedullary location and the melanotic component of the reported lesion make it exceedingly rare. We will present our case, theories as to the origin of these tumors, clues in radiographic identification, and current clinical follow-up recommendations.
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BACKGROUND: Rheumatoid arthritis (RA) is the most common inflammatory disease involving the spine. It has a predilection for involving the craniocervical spine. Despite widespread involvement of the cervical spine with RA, few patients need surgery. The 3 major spinal manifestations of RA in the cervical spine are basilar invagination, atlantoaxial instability, and subaxial subluxations. Surgical management of RA involving the craniovertebral junction remains a challenge despite a decline in severe cases and an improvement in surgical techniques. METHODS: We conducted an exhaustive review of English-language publications discussing RA involving the craniovertebral junction. We paid special attention to publications detailing modern surgical management of these conditions. In addition, we outline our own surgical experience with such patients. RESULTS: We discuss alternative surgical methods for treating basilar invagination, atlantoaxial instability, and concurrent subaxial subluxations. We detail our surgical technique for transoral odontoidectomy, occipital cervical fusion, and atlantoaxial fusion. We detail the use of spinal surgical navigation in both of these procedures. CONCLUSION: Surgical management of RA remains a challenging field. There clearly has been a decrease in cases of mutilating RA involving the craniovertebral junction. Surgical techniques for managing these conditions have steadily improved.
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Artritis Reumatoide/cirugía , Articulación Atlantoaxoidea/cirugía , Articulación Atlantooccipital/cirugía , Fusión Vertebral/métodos , Espondiloartritis/cirugía , Artritis Reumatoide/diagnóstico por imagen , Artritis Reumatoide/patología , Articulación Atlantoaxoidea/diagnóstico por imagen , Articulación Atlantoaxoidea/patología , Articulación Atlantooccipital/diagnóstico por imagen , Articulación Atlantooccipital/patología , Vértebra Cervical Axis/diagnóstico por imagen , Vértebra Cervical Axis/patología , Vértebra Cervical Axis/cirugía , Atlas Cervical/diagnóstico por imagen , Atlas Cervical/patología , Atlas Cervical/cirugía , Humanos , Hueso Occipital/diagnóstico por imagen , Hueso Occipital/patología , Hueso Occipital/cirugía , Radiografía , Fusión Vertebral/instrumentación , Fusión Vertebral/tendencias , Espondiloartritis/diagnóstico por imagen , Espondiloartritis/patologíaRESUMEN
OBJECT: Stereotactic radiosurgery (SRS) has proven to be a safe and effective treatment for many patients with intracranial meningiomas. Nevertheless, the morbidity associated with radiosurgery of larger meningiomas is poorly understood. METHODS: The authors performed a retrospective review of 116 patients who underwent SRS for meningiomas (WHO Grade I) > 10 cm3 between 1990 and 2007, with a minimum follow-up of 12 months. Patients with atypical or malignant meningiomas and those who received prior radiotherapy were excluded. The average tumor volume was 17.5 cm3 (range 10.1-48.6 cm3); the average tumor margin dose was 15.1 Gy (range 12-18 Gy); and the mean follow-up duration was 70.1 months (range 12-199 months). RESULTS: Tumor control was 99% at 3 years and 92% at 7 years after radiosurgery. Thirty complications after radiosurgery were noted in 27 patients (23%), including 7 cases of seizures, 6 cases of hemiparesis, 5 cases of trigeminal injury, 4 cases of headaches, 3 cases of diplopia, 2 cases each of cerebral infarction and ataxia, and 1 case of hearing loss. Patients with supratentorial tumors experienced a higher complication rate compared with patients with skull base tumors (44% compared with 18%) (hazard ratio 2.9, 95% CI 1.3-6.7, p = 0.01). CONCLUSIONS: The morbidity associated with SRS for patients with benign meningiomas > 10 cm(3) is greater for supratentorial tumors compared with skull base tumors. Whereas radiosurgery is relatively safe for patients with large-volume skull base meningiomas, resection should remain the primary disease management for the majority of patients with large-volume supratentorial meningiomas.
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Meningioma/patología , Meningioma/cirugía , Radiocirugia/instrumentación , Neoplasias de la Base del Cráneo/patología , Neoplasias de la Base del Cráneo/cirugía , Adulto , Anciano , Anciano de 80 o más Años , Ataxia/epidemiología , Ataxia/etiología , Infarto Cerebral/epidemiología , Infarto Cerebral/etiología , Femenino , Estudios de Seguimiento , Cefalea/epidemiología , Cefalea/etiología , Trastornos de la Audición/epidemiología , Trastornos de la Audición/etiología , Humanos , Masculino , Persona de Mediana Edad , Invasividad Neoplásica , Estadificación de Neoplasias , Radiocirugia/efectos adversos , Estudios Retrospectivos , Neoplasias Supratentoriales/patología , Neoplasias Supratentoriales/cirugía , Adulto JovenRESUMEN
The Wireless Instantaneous Neurotransmitter Concentration Sensing System (WINCS) measures extracellular neurotransmitter concentration in vivo and displays the data graphically in nearly real time. WINCS implements two electroanalytical methods, fast-scan cyclic voltammetry (FSCV) and fixed-potential amperometry (FPA), to measure neurotransmitter concentrations at an electrochemical sensor, typically a carbon-fiber microelectrode. WINCS comprises a battery-powered patient module and a custom software application (WINCSware) running on a nearby personal computer. The patient module impresses upon the electrochemical sensor either a constant potential (for FPA) or a time-varying waveform (for FSCV). A transimpedance amplifier converts the resulting current to a signal that is digitized and transmitted to the base station via a Bluetooth radio link. WINCSware controls the operational parameters for FPA or FSCV, and records the transmitted data stream. Filtered data is displayed in various formats, including a background-subtracted plot of sequential FSCV scans - a representation that enables users to distinguish the signatures of various analytes with considerable specificity. Dopamine, glutamate, adenosine and serotonin were selected as analytes for test trials. Proof-of-principle tests included in vitro flow-injection measurements and in vivo measurements in rat and pig. Further testing demonstrated basic functionality in a 3-Tesla MRI unit. WINCS was designed in compliance with consensus standards for medical electrical device safety, and it is anticipated that its capability for real-time intraoperative monitoring of neurotransmitter release at an implanted sensor will prove useful for advancing functional neurosurgery.
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Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , Monitoreo Intraoperatorio/instrumentación , Monitoreo Intraoperatorio/métodos , Encéfalo/metabolismo , Dopamina/metabolismo , Humanos , Serotonina/metabolismo , Programas InformáticosRESUMEN
BACKGROUND CONTEXT: Pedicle screw malposition rates using conventional techniques have been reported to occur with a frequency of 6% to 41%. The upper thoracic spine (T1-T3) is a challenging area for pedicle screw placement secondary to the small size of the pedicles, the inability to visualize this area with lateral fluoroscopy, and significant consequences for malpositioned screws. We describe our experience placing 150 pedicle screws in the T1-T3 levels using three-dimensional (3D) image guidance. PURPOSE: The aim of this study was to assess the accuracy of 3D image guidance for placing pedicle screws in the first three thoracic vertebrae. STUDY DESIGN: The accuracy of pedicle screw placement in the first three thoracic vertebrae was evaluated using postoperative thin-section computed tomography (CT) scans of the cervicothoracic region. PATIENT SAMPLE: Thirty-four patients who underwent cervicothoracic fusion were included. OUTCOME MEASURES: Radiological investigation with CT scans was performed during the postoperative period. METHODS: Thirty-four consecutive patients underwent cervicothoracic instrumentation and fusion for a total of 150 pedicle screws placed in the first three thoracic vertebrae. All screws were placed using 3D image guidance. Medical records and postoperative imaging of the cervicothoracic junction for each patient were retrospectively reviewed. An independent radiologist reviewed the placement of the pedicle screws and assessed for pedicle breach. All cortical violations were reported as Grade 1, 0 to 2 mm; Grade 2, 2 to 4 mm; and Grade 3, greater than 4 mm. RESULTS: Overall, 140 (93.3%) out of 150 screws were contained solely in the desired pedicle. All 10 pedicle violations were Grade 1. The direction of pedicle violation included three medial, four inferior, two superior, and one minor anterolateral vertebral body. No complication occurred as a result of screw placement or the use of image guidance. CONCLUSIONS: Upper thoracic pedicle screw placement is technically demanding as a result of variable pedicle anatomy and difficulty with two-dimensional visualization. This study demonstrates the accuracy and reliability of 3D image guidance when placing pedicle screws in this region. Advantages of this technology in our practice include safe and accurate placement of spinal instrumentation with little to no radiation exposure to the surgeon and operating room staff.
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Tornillos Óseos , Fusión Vertebral/métodos , Cirugía Asistida por Computador , Vértebras Torácicas/cirugía , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Imagenología Tridimensional/métodos , Masculino , Persona de Mediana Edad , Monitoreo Intraoperatorio/métodos , Estudios Retrospectivos , Fusión Vertebral/instrumentaciónRESUMEN
OBJECT: Emerging evidence supports the hypothesis that modulation of specific central neuronal systems contributes to the clinical efficacy of deep brain stimulation (DBS) and motor cortex stimulation (MCS). Real-time monitoring of the neurochemical output of targeted regions may therefore advance functional neurosurgery by, among other goals, providing a strategy for investigation of mechanisms, identification of new candidate neurotransmitters, and chemically guided placement of the stimulating electrode. The authors report the development of a device called the Wireless Instantaneous Neurotransmitter Concentration System (WINCS) for intraoperative neurochemical monitoring during functional neurosurgery. This device supports fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode (CFM) for real-time, spatially and chemically resolved neurotransmitter measurements in the brain. METHODS: The FSCV study consisted of a triangle wave scanned between -0.4 and 1 V at a rate of 300 V/second and applied at 10 Hz. All voltages were compared with an Ag/AgCl reference electrode. The CFM was constructed by aspirating a single carbon fiber (r = 2.5 mum) into a glass capillary and pulling the capillary to a microscopic tip by using a pipette puller. The exposed carbon fiber (that is, the sensing region) extended beyond the glass insulation by approximately 100 microm. The neurotransmitter dopamine was selected as the analyte for most trials. Proof-of-principle tests included in vitro flow injection and noise analysis, and in vivo measurements in urethane-anesthetized rats by monitoring dopamine release in the striatum following high-frequency electrical stimulation of the medial forebrain bundle. Direct comparisons were made to a conventional hardwired system. RESULTS: The WINCS, designed in compliance with FDA-recognized consensus standards for medical electrical device safety, consisted of 4 modules: 1) front-end analog circuit for FSCV (that is, current-to-voltage transducer); 2) Bluetooth transceiver; 3) microprocessor; and 4) direct-current battery. A Windows-XP laptop computer running custom software and equipped with a Universal Serial Bus-connected Bluetooth transceiver served as the base station. Computer software directed wireless data acquisition at 100 kilosamples/second and remote control of FSCV operation and adjustable waveform parameters. The WINCS provided reliable, high-fidelity measurements of dopamine and other neurochemicals such as serotonin, norepinephrine, and ascorbic acid by using FSCV at CFM and by flow injection analysis. In rats, the WINCS detected subsecond striatal dopamine release at the implanted sensor during high-frequency stimulation of ascending dopaminergic fibers. Overall, in vitro and in vivo testing demonstrated comparable signals to a conventional hardwired electrochemical system for FSCV. Importantly, the WINCS reduced susceptibility to electromagnetic noise typically found in an operating room setting. CONCLUSIONS: Taken together, these results demonstrate that the WINCS is well suited for intraoperative neurochemical monitoring. It is anticipated that neurotransmitter measurements at an implanted chemical sensor will prove useful for advancing functional neurosurgery.
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Encéfalo/metabolismo , Técnicas Electroquímicas/instrumentación , Monitoreo Intraoperatorio/instrumentación , Neurotransmisores/metabolismo , Telemetría/instrumentación , Animales , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , Estimulación Encefálica Profunda , Dopamina/metabolismo , Estimulación Eléctrica , Técnicas Electroquímicas/métodos , Masculino , Modelos Animales , Monitoreo Intraoperatorio/métodos , Neurocirugia/instrumentación , Neurocirugia/métodos , Norepinefrina/metabolismo , Ratas , Ratas Sprague-Dawley , Serotonina/metabolismo , Telemetría/métodosRESUMEN
OBJECT: In a companion study, the authors describe the development of a new instrument named the Wireless Instantaneous Neurotransmitter Concentration System (WINCS), which couples digital telemetry with fast-scan cyclic voltammetry (FSCV) to measure extracellular concentrations of dopamine. In the present study, the authors describe the extended capability of the WINCS to use fixed potential amperometry (FPA) to measure extracellular concentrations of dopamine, as well as glutamate and adenosine. Compared with other electrochemical techniques such as FSCV or high-speed chronoamperometry, FPA offers superior temporal resolution and, in combination with enzyme-linked biosensors, the potential to monitor nonelectroactive analytes in real time. METHODS: The WINCS design incorporated a transimpedance amplifier with associated analog circuitry for FPA; a microprocessor; a Bluetooth transceiver; and a single, battery-powered, multilayer, printed circuit board. The WINCS was tested with 3 distinct recording electrodes: 1) a carbon-fiber microelectrode (CFM) to measure dopamine; 2) a glutamate oxidase enzyme-linked electrode to measure glutamate; and 3) a multiple enzyme-linked electrode (adenosine deaminase, nucleoside phosphorylase, and xanthine oxidase) to measure adenosine. Proof-of-principle analyses included noise assessments and in vitro and in vivo measurements that were compared with similar analyses by using a commercial hardwired electrochemical system (EA161 Picostat, eDAQ; Pty Ltd). In urethane-anesthetized rats, dopamine release was monitored in the striatum following deep brain stimulation (DBS) of ascending dopaminergic fibers in the medial forebrain bundle (MFB). In separate rat experiments, DBS-evoked adenosine release was monitored in the ventrolateral thalamus. To test the WINCS in an operating room setting resembling human neurosurgery, cortical glutamate release in response to motor cortex stimulation (MCS) was monitored using a large-mammal animal model, the pig. RESULTS: The WINCS, which is designed in compliance with FDA-recognized consensus standards for medical electrical device safety, successfully measured dopamine, glutamate, and adenosine, both in vitro and in vivo. The WINCS detected striatal dopamine release at the implanted CFM during DBS of the MFB. The DBS-evoked adenosine release in the rat thalamus and MCS-evoked glutamate release in the pig cortex were also successfully measured. Overall, in vitro and in vivo testing demonstrated signals comparable to a commercial hardwired electrochemical system for FPA. CONCLUSIONS: By incorporating FPA, the chemical repertoire of WINCS-measurable neurotransmitters is expanded to include glutamate and other nonelectroactive species for which the evolving field of enzyme-linked biosensors exists. Because many neurotransmitters are not electrochemically active, FPA in combination with enzyme-linked microelectrodes represents a powerful intraoperative tool for rapid and selective neurochemical sampling in important anatomical targets during functional neurosurgery.
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Adenosina/metabolismo , Encéfalo/metabolismo , Dopamina/metabolismo , Técnicas Electroquímicas/instrumentación , Ácido Glutámico/metabolismo , Monitoreo Intraoperatorio/instrumentación , Neurocirugia/instrumentación , Animales , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , Estimulación Encefálica Profunda , Técnicas Electroquímicas/métodos , Femenino , Masculino , Modelos Animales , Monitoreo Intraoperatorio/métodos , Corteza Motora/metabolismo , Neurocirugia/métodos , Ratas , Ratas Sprague-Dawley , Porcinos , Telemetría/instrumentación , Telemetría/métodos , Tálamo/metabolismoRESUMEN
Intractable neuropathic face pain is a syndrome of unremitting severe pain that stems from abnormal nociceptive processing at various levels of the trigeminal system. Treatment of this debilitating condition has long presented a challenge for physicians due to its refractoriness to standard pharmacologic therapies. With few viable treatments, surgical procedures such as motor cortex stimulation (MCS) and deep brain stimulation (DBS) provide additional options. This article reviews the current literature and practices regarding patient selection criteria, potential mechanisms of action, surgical technique, and outcome of patients with neuropathic face pain treated with MCS and DBS.
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Estimulación Encefálica Profunda , Dolor Facial/terapia , Corteza Motora/cirugía , Dolor Facial/clasificación , Humanos , Corteza Motora/anatomía & histología , Selección de Paciente , Resultado del TratamientoRESUMEN
Deep Brain Stimulation (DBS) provides therapeutic benefit for several neuropathologies including Parkinson's disease (PD), epilepsy, chronic pain, and depression. Despite well established clinical efficacy, the mechanism(s) of DBS remains poorly understood. In this review we begin by summarizing the current understanding of the DBS mechanism. Using this knowledge as a framework, we then explore a specific hypothesis regarding DBS of the subthalamic nucleus (STN) for the treatment of PD. This hypothesis states that therapeutic benefit is provided, at least in part, by activation of surviving nigrostriatal dopaminergic neurons, subsequent striatal dopamine release, and resumption of striatal target cell control by dopamine. While highly controversial, we present preliminary data that are consistent with specific predications testing this hypothesis. We additionally propose that developing new technologies, e.g., human electrometer and closed-loop smart devices, for monitoring dopaminergic neurotransmission during STN DBS will further advance this treatment approach.
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OBJECTIVE: This study is designed to describe the association between benign intracranial hypertension (BIH) and spontaneous cerebrospinal fluid (CSF) rhinorrhea and address the effect of extracranial venous flow dynamics on intracranial pressure (ICP). METHODS: We present a 58-year-old woman with refractory spontaneous CSF rhinorrhea who was later found to have superior vena cava syndrome. The patient had undergone two prior transnasal endoscopic repair attempts. In retrospect, a preoperative magnetic resonance venogram (MRV) suggested very prolonged cerebral transit time, despite otherwise normal intracranial venous anatomy. RESULTS: The CSF leak was repaired through a bifrontal craniotomy. The intraoperative and postoperative course was complicated due to the patient's significant comorbidities. She ultimately made a good recovery and has not had any further CSF rhinorrhea in more than 2 years of follow-up. CONCLUSIONS: Refractory, spontaneous CSF leak must prompt aggressive investigation for multiple causes of elevated ICP. A cerebral transit time can be obtained from scout imaging when a magnetic resonance angiogram or MRV is performed, and this may disclose elevated ICP if it is prolonged. If endoscopic transnasal repair fails, craniotomy and direct suture repair and autologous tissue reinforcement of the skull base may prove successful and durable, even if BIH persists.