Intraparenchymal electrode

OBJECTIVE: The aim of this study was to evaluate the degree of brain tissue injury that could be potentially induced by the introduction of a) microrecording electrodes, b) macrostimulation electrodes, or c) chronic stimulation electrodes. We aimed to evaluate whether the use of five simultaneous microrecording tracks is associated with any brain injury not detectable by conventional imaging such as CT or MRI. MATERIALS AND METHODS: The study included 61 patients who underwent surgery for implantation of 121 DBS leads...

Invasive electroencephalographic monitoring with implantable subdural electrodes and intraparenchymal depth electrodes has become a basic tenet of epilepsy surgery. Improved localization of epileptic foci justifies the secondary procedure and monitoring period in many patients. Informed use of invasive monitoring in conjunction with imaging and functional studies makes epilepsy surgery a smaller, safer, and more effective endeavor. Herein we review the history, indications, implementation, and foreseeable future of grid, strip, and depth electrode use...

Neural networks that span the medial temporal lobe (MTL), prefrontal cortex, and posterior cortical regions are essential to episodic memory function in humans. Encoding and retrieval are supported by the engagement of both distinct neural pathways across the cortex and common structures within the medial temporal lobes. However, the degree to which memory performance can be determined by neural processing that is common to encoding and retrieval remains to be determined. To identify neural signatures of successful memory function, we administered a delayed free-recall task to 187 neurosurgical patients implanted with subdural or intraparenchymal depth electrodes...

OBJECTIVE The aim of the present study was to evaluate the usefulness of navigated transcranial magnetic stimulation (nTMS) as a prognostic predictor for upper-extremity motor functional recovery from postsurgical neurological deficits. METHODS Preoperative and postoperative nTMS studies were prospectively applied in 14 patients (mean age 39 ± 12 years) who had intraparenchymal brain neoplasms located within or adjacent to the motor eloquent area in the cerebral hemisphere. Mapping by nTMS was done 3 times, i...

BACKGROUND: When wounds are benign, diagnosis of deep brain stimulation (DBS) electrode infection and associated intraparenchymal infection can be challenging. Only a couple, such cases exist in literature. Since infections of the central nervous system can be life-threatening, prompt diagnosis is necessary to prevent neurological injury. Employed within the appropriate context, magnetic resonance imaging (MRI) of the brain, as well as laboratory data and clinical presentation, may help guide diagnosis...

OBJECTIVE Contemporary theories of the pathophysiology of movement disorders emphasize abnormal oscillatory activity in basal ganglia-thalamocortical loops, but these have been studied in humans mainly using depth recordings. Recording from the surface of the cortex using electrocorticography (ECoG) provides a much higher amplitude signal than depth recordings, is less susceptible to deep brain stimulation (DBS) artifacts, and yields a surrogate measure of population spiking via "broadband gamma" (50-200 Hz) activity...

OBJECT The degree of clinical improvement achieved by deep brain stimulation (DBS) is largely dependent on the accuracy of lead placement. This study reports on the evaluation of intraoperative MRI (iMRI) for adjusting deviated electrodes to the accurate anatomical position during DBS surgery and acute intracranial changes. METHODS Two hundred and six DBS electrodes were implanted in the subthalamic nucleus (STN) in 110 patients with Parkinson disease. All patients underwent iMRI after implantation to define the accuracy of lead placement...

BACKGROUND: Successful surgical treatment of epilepsy requires accurate definition of areas of ictal onset and eloquent brain. Although invasive monitoring can help, subdural grids cannot sample sulci or subcortical tissue; traditional stereoelectroencephalography depth electrodes are usually placed too far apart to provide sufficient resolution for mapping. OBJECTIVE: To report a strategy of depth electrode placement in a dense array to allow precise anatomic localization of epileptic and eloquent cortex...

Pt/Ir electrodes have been extensively used in neurophysiology research in recent years as they provide a more inert recording surface as compared to tungsten or stainless steel. While floating microelectrode arrays (FMA) consisting of Pt/Ir electrodes are an option for neuroprosthetic applications, long-term in vivo functional performance characterization of these FMAs is lacking. In this study, we have performed comprehensive abiotic-biotic characterization of Pt/Ir arrays in 12 rats with implant periods ranging from 1 week up to 6 months...

BACKGROUND: Spreading depolarization events following ischemic and traumatic brain injury are associated with poor patient outcome. Currently, monitoring these events is limited to patients in whom subdural electrodes can be placed at open craniotomy. This study examined whether these events can be detected using intra-cortical electrodes, opening the way for electrode insertion via burr hole. METHODS: Animal work was carried out on adult Sprague-Dawley rats in a laboratory setting to investigate the feasibility of recording depolarization events...

Following deep brain stimulation (DBS) surgery, a variety of potential mechanical or functional complications ranging from perioperative events to hardware malfunction may occur. We present 2 patients who developed a unique complication of cyst formation at the tip of the DBS electrode in the absence of infection. One patient had a unilateral ventral intermediate lead placement for essential tremor, and the other had bilateral subthalamic nucleus (STN) placement for Parkinson's disease. After a period of symptom control, at 3 and 8 months after surgery, respectively, both patients developed new neurological deficits and were found to have a cyst at the left DBS lead tip...

Epilepsy work-up is based on history and scalp EEG. Drug resistant epilepsy should be evaluated in a dedicated epilepsy surgery unit. Sometimes non-invasive studies fail to localize the epileptogenic area in focal epilepsy and then the work up can be complemented with intracranial EEG. Intracranial electrodes are implanted either in the subdural space or intraparenchymally. This is followed by one to two weeks of EEG monitoring in a specialized videotelemetry unit. Intracranial EEG helps to define the borders of the epileptogenic area for resection...

BACKGROUND: Electrical impedance tomography (EIT) is a method that can render continuous graphical cross-sectional images of the brain's electrical properties. Because these properties can be altered by variations in water content, shifts in sodium concentration, bleeding, and mass deformation, EIT has promise as a sensitive instrument for head injury monitoring to improve early recognition of deterioration and to observe the benefits of therapeutic intervention. This study presents a swine model of head injury used to determine the detection capabilities of an inexpensive bedside EIT monitoring system with a novel intracranial pressure (ICP)/EIT electrode combination sensor on induced intraparenchymal mass effect, intraparenchymal hemorrhage, and cessation of brain blood flow...

OBJECT: In this prospective study the authors' objective was to evaluate the accuracy of deep brain stimulation (DBS) electrode placement using image guidance for direct anatomical targeting with intraoperative CT. METHODS: Preoperative 3-T MR images were merged with intraoperative CT images for planning. Electrode targets were anatomical, based on the MR images. A skull-mounted NexFrame system was used for electrode placement, and all procedures were performed under general anesthesia...

OBJECTIVE: Responsive neurostimulation (RNS®) is an investigational treatment modality for intractable focal epilepsy. We analyzed impedance values over time to gain a better understanding of RNS device stability, potential differences between depth and strip electrodes, and general implications of long-term electrode implantation. MATERIALS AND METHODS: Impedance measurements were retrospectively reviewed from seven patients over a 3-year period. Statistical analysis was performed to investigate trends in impedance values over time and to determine if any differences existed between the means and variances of impedance values for the two different electrodes...

Spreading depolarization describes a sustained neuronal and astroglial depolarization with abrupt ion translocation between intraneuronal and extracellular space leading to a cytotoxic edema and silencing of spontaneous activity. Spreading depolarizations occur abundantly in acutely injured human brain and are assumed to facilitate neuronal death through toxic effects, increased metabolic demand, and inverse neurovascular coupling. Inverse coupling describes severe hypoperfusion in response to spreading depolarization...

Intracranial bleeding following stereoelectroencephalography (sEEG) is rare and commonly occurs early after electrode implantation. The authors report the case of a delayed intracranial hematoma following sEEG. This 10-year-old boy was referred to the authors' department to undergo an sEEG study for intractable epilepsy, with the hypothesis of a single localized epileptic zone in the left precentral region. To perform the exploration, 14 depth electrodes were implanted under stereotactic conditions. The results of a postoperative CT scan performed routinely at the end of the surgical procedure were normal...

For nearly 55 years, tungsten microwires have been widely used in neurophysiological experiments in animal models to chronically record neuronal activity. While tungsten microwires initially provide stable recordings, their inability to reliably record high-quality neural signals for tens of years has limited their efficacy for neuroprosthetic applications in humans. Comprehensive understanding of the mechanisms of electrode performance and failure is necessary for developing next generation neural interfaces for humans...

Intracranial pharmacotherapy is a novel strategy to treat drug refractory, localization-related epilepsies not amenable to resective surgery. The common feature of the method is the use of some type of antiepileptic drug (AED) delivery device placed inside the cranium to prevent or stop focal seizures. This distinguishes it from other nonconventional methods, such as intrathecal pharmacotherapy, electrical neurostimulation, gene therapy, cell transplantation, and local cooling. AED-delivery systems comprise drug releasing polymers and neuroprosthetic devices that can deliver AEDs into the brain via intraparenchymal, ventricular, or transmeningeal routes...

This study explored the use of non-radioactive 2-deoxy glucose (2DG)-labeled magnetonanoparticles (MNP) and magnetic resonance imaging (MRI) to detect functional activity during rest, peripheral stimulation, and epileptic seizures, in animal models. Non-radioactive 2DG was covalently attached to magnetonanoparticles composed of iron oxide and dextran and intravenous (tail) injections were performed. 2DG-MNP was injected in resting and stimulated naïve rodents and the subsequent MRI was compared to published (14)C-2DG autoradiography data...