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PubMed2005

Current density distributions, field distributions and impedance analysis of segmented deep brain stimulation electrodes.

Deep brain stimulation (DBS) electrodes are designed to stimulate specific areas of the brain. The most widely used DBS electrode has a linear array of 4 cylindrical contacts that can be selectively turned on depending on the placement of the electrode and the specific area of the brain to be stimulated. The efficacy of DBS therapy can be improved by localizing the current delivery into specific populations of neurons and by increasing the power efficiency through a suitable choice of electrode geometrical characteristics. We investigated segmented electrode designs created by sectioning each cylindrical contact into multiple rings. Prototypes of these designs, made with different materials and larger dimensions than those of clinical DBS electrodes, were evaluated in vitro and in simulation. A finite element model was developed to study the effects of varying the electrode characteristics on the current density and field distributions in an idealized electrolytic medium and in vitro experiments were conducted to measure the electrode impedance. The current density over the electrode surface increased towards the edges of the electrode, and multiple edges increased the non-uniformity of the current density profile. The edge effects were more pronounced over the end segments than over the central segments. Segmented electrodes generated larger magnitudes of the second spatial difference of the extracellular potentials, and thus required lower stimulation intensities to achieve the same level of neuronal activation as solid electrodes. For a fixed electrode conductive area, increasing the number of segments (edges) decreased the impedance compared to a single solid electrode, because the average current density over the segments increased. Edge effects played a critical role in determining the current density distributions, neuronal excitation patterns, and impedance of cylindrical electrodes, and segmented electrodes provide a means to increase the efficiency of DBS.

Animals↗
PubMed2005

The North American survey of placement and adjustment strategies for deep brain stimulation.

BACKGROUND: Deep brain stimulation (DBS) is gaining wide acceptance as treatment for Parkinson's disease (PD), essential tremor, and dystonia. METHODS: A 40-item questionnaire commissioned by the DBS Study Group was sent to 46 centers that had performed at least 25 DBS implantations. These centers were identified through the DBS Study Group, other professional societies, and with the assistance of the Medtronic Corporation. The results were then tabulated and descriptive analyses were performed. RESULTS: Thirty-six of 47 centers (77%) responded, they had implanted 4,553 patients. The timing for bilaterally implanted patients varied, as 13 sites almost always implanted simultaneously whereas 14 sites almost never implanted simultaneously. Stereotactic frames included Leksell (n = 19), CRW (n = 15) and Compass (n = 2). Post-placement imaging was routinely performed by almost all centers and included MRI (n = 23), CT (n = 4), CT/MRI variably (n = 5), and ventriculography (n = 1). Two centers used more than one electrode per side. The 34 centers that used a single electrode averaged 2.3 +/- 1.4 passes per electrode (range: 1-18 passes). Most centers used macro-stimulation to confirm placement by assessing the intra-operative clinical response (n = 34), and to assess for adverse events (n = 26) at high voltages, averaging 6.7 +/- 2.3 V (range: 4-10). The initial activation averaged 18 +/- 12 days after electrode placement (average range: 11 +/- 10 to 28 +/- 18 days, absolute range: 1-90 days). Most sites had several programmers; however, the primary programmers were neurology staff (n = 15), the neurologist (n = 13), neurosurgery staff (n = 6), the neurosurgeon (n = 2), or a physiatrist (n = 1). Twelve centers automatically reduced PD medications on the day of initial activation, 9 centers reduced them variably, and 16 centers initially did not reduce them. Eventually, 80.4% of patients were reported to have some dose reduction, and 47.1% had a greater than 50% reduction of PD medications. CONCLUSIONS: Strategies regarding DBS placement and adjustment vary in North America.

Antiparkinson Agents↗
PubMed2006

A simple stereotactic method for frameless deep brain stimulation.

BACKGROUND: Deep brain stimulation (DBS) is widely used to treat advanced Parkinson's disease, other movement and psychiatric disorders. DBS implantation requires application of a stereotactic frame throughout a lengthy procedure, making it uncomfortable and tiring. We designed a stereotactic cube to stage the operation, perform frameless microelectrode recording (MER) and fix the DBS. METHODS: The 15-mm cube is implanted in a burr hole using bone cement. It contains 5 parallel trajectories (central + 4 around). It is aligned by stereotactic frame so that central trajectory reaches the target. Frameless MER is performed by attaching a micro-driver to the cube using 2-5 cannulae (4 cm). The DBS is fixed to the cube by a mini-plate and 1 screw. Ninety-six cubes were compared with 43 Bennet spheres (BS). RESULTS: No cube moved compared to 2 (5%) BS (p < 0.05). The final trajectory was central in 64.4% of cubes compared to 47.5% of BS, and the final target was >2 mm out in no cubes compared to 12.5% of BS (p < 0.01). Infection and haemorrhage were observed in 2.5% and 3.3% of cubes, respectively, while 5% of BS developed infection, 5% haemorrhage and 7.5% skin erosion. CONCLUSIONS: This method is simple and effective in staging DBS procedures, performing frameless MER and DBS implantation, fixation and revision.

Adult↗
PubMed2002

Hardware-related complications after placement of thalamic deep brain stimulator systems.

Deep brain stimulation (DBS) has become a common therapeutic approach to patients with movement disorders. We evaluated results from two centers in a large metropolitan area where DBS systems are implanted into the thalamus for patients with tremor. Although all implanted systems led to an improvement in tremor, morbidity related to the hardware system occurred. A total of 23 hardware problems were noted in 66 patients undergoing implantation of 66 DBS systems (27% of patients). The most common problem included breakage of the electrode lead in its extracranial location, system infection, battery or connector problems, lead migration, and hemorrhage. Management was tailored to the specific hardware-related problem. Modifications in both surgical technique and hardware design should reduce the incidence of complications. Surgeons who place DBS systems should be aware of the spectrum of problems that can be associated with the device and its placement.

Electric Stimulation Therapy↗
PubMed2003

Multiple sequential image-fusion and direct MRI localisation of the subthalamic nucleus for deep brain stimulation.

AIM: Deep brain stimulation (DBS) is the treatment of choice for advanced Parkinson's disease. The target co-ordinates are traditionally calculated in relation to the intercommissural distance. Anterior (AC) and posterior commissures (PC) may be visualised by the means of ventriculography, CT or MRI. METHODS: We have studied the efficacy of direct visualisation of the subthalamic-red nucleus complex on MRI, the advantage of fusion of stereotactic CT and MR images (Multiple Sequences Image Fusion - MuSIF). These methods are combined with double check of indirect calculation of the target co-ordinates based on AC-PC line, as well as the corrispondence to the stereotactic electronic atlas. RESULTS: Subthalamic nucleus (STN) was well recognisable in fused images in all 22 sides. At 3 months from surgery it was possible to reduce 76% of L-dopa equivalent daily dose. Dyskine-sias reduced to 50% and motor fluctuation up to 45%. CONCLUSION: In our experience MuSIF offers very high rate of accuracy in calculation of target co-ordinates. Direct visualisation of STN in MR and MuSIF are reliable and facilitate the accuracy of identification of target co-ordinates. Intraoperative neurophysiological recording increases the accuracy of microelectrode position.

Antiparkinson Agents↗
PubMed2001

[Neurosurgical therapy of Parkinson disease. Deep brain stimulation].

The introduction of continuous high frequency stimulation (deep brain stimulation) into functional neurosurgery has opened up new avenues in the treatment of Parkinson's disease. This new technique expands the therapeutic possibilities available to those patients in whom, over the years, the effectiveness of drug treatment has deteriorated, or severe side effects developed. In the individual case, the decision as to whether to operate is taken on the basis of interdisciplinary cooperation between the care-providing neurologist and the neurosurgeon specialized in this particular field.

Basal Ganglia↗
PubMedDate not supplied

[Psychiatric symptoms of Parkinson's disease following deep brain stimulation surgery on the subthalamic nucleus].

AIM: To review the increasing number of papers that report diverse neuropsychiatric disorders that happen in patients diagnosed of Parkinson's disease submitted to brain deep stimulation of subthalamic nuclei with high frequency current. DEVELOPMENT: It is a fact the need to evaluate carefully all the patients who have to submit to this surgical procedure analyzing previous psychiatric history, and the possible appearance of psychiatric sphere symptoms after surgery. The acute depression and the euphoric moods (than can occur immediately after surgery) and major depression, obsession, widespread anxiety and substance abuse (among those of more delayed appearance) constitute examples of this pathology. The treatment of previous psychiatric disorders is forced in all cases and specially relevant in the major depression when suicide ideas coexist. CONCLUSIONS: Information that allow to predict the risk of developing depressive disorders in the postoperative period does not exist at present time, though it is more predictable that it happens in those patients with previous severe depressive history. In general, euphoric moods, apathy and depression, usually are transient and of multifactorial origin that includes the existence of endogenous predisposition, the change to an independence pattern after surgery, the psychotropic effect of levodopa, and the high frequency current stimulation effect on the non motor structures target and in the adjacent regions. It must be outlined that it is possible the appearance of psychotic symptoms after brain deep stimulation of subthalamic nuclei in patients with ideal results on motor disability.

Deep Brain Stimulation↗
PubMed2006

Vagus nerve stimulation and deep brain stimulation for treatment resistant depression.

Neurostimulation techniques are potentially useful options for severely depressed patients who have failed trial after trial of medication and psychotherapy. Cervical VNS therapy for chronic or recurrent depression which does not resolve with pharmacotherapy was recently approved by the FDA. DBS for severe intractable depression has been studied in two pilot studies with very few patients to date. Further investigations are currently underway in order to more fully evaluate both of these neurostimulation therapies, with the hope of substantially improving the treatment of refractory depression.

Deep Brain Stimulation↗
PubMed2005

Safety considerations for deep brain stimulation: review and analysis.

Deep brain stimulation has emerged rapidly as an effective therapy for movement disorders. Deep brain stimulation includes an implanted brain electrode and a pacemaker-like implanted pulse generator. The clinical application of deep brain stimulation proceeded in the absence of clear understandings of its mechanisms of action or extensive preclinical studies of safety and efficacy. Post mortem studies suggest that there is a loss of neurons in proximity to the active electrode, but the resulting lesions are not sufficient to treat the disorder and efficacy requires continued stimulation. Overall complication rates can exceed 25%, and permanent neurologic sequelae result in 4-6% of cases. As the application of deep brain stimulation expands, it is critical to understand the origin of adverse events and the delivery of nondamaging stimulation.

Deep Brain Stimulation↗
PubMed2002

Deep brain stimulation for Parkinson's disease: disrupting the disruption.

Many people are disabled by Parkinson's disease (PD) despite the drug treatments that are currently available. For these patients, neurosurgery has the potential to help restore their function. The most effective neurosurgical procedures to date use electrical stimulation--deep brain stimulation (DBS)--of small targets in the brain by use of a pacemaker-like device to deliver constant stimulation. Although these operations can produce striking results, the mechanism by which delivery of electrical stimulation to targets deep in the brain can restore function in the motor system is not clear. This type of surgery probably works by interfering with and shutting down abnormal brain activity in areas where the current is delivered, such as the thalamus, globus pallidus, or the subthalamic nucleus. With this abnormal neuronal activity neutralised, motor areas of the brain can resume their function and normal movements are reinstated. Current research is aimed at elucidating how DBS works and using this information to develop better treatments for patients with PD and other neurological disorders.

Animals↗
PubMed2005

Deep brain stimulation for refractory obsessive-compulsive disorder.

BACKGROUND: Neurosurgery (anterior capsulotomy) has been beneficial to many patients with debilitating, refractory obsessive-compulsive disorder (OCD), but the irreversibility of the procedure is an important limitation to its use. Nondestructive, electrical stimulation (deep brain stimulation; DBS) has proven an effective alternative to ablative surgery for neurological indications, suggesting potential utility in place of capsulotomy for OCD. METHODS: The effects of DBS for OCD were examined in four patients in a short-term, blinded, on-off design and long-term, open follow-up. The patients had incapacitating illness, refractory to standard treatments. Hardware developed for movement disorder treatment was surgically implanted, with leads placed bilaterally in the anterior limbs of their internal capsules. Patients received stimulation in a randomized "on-off" sequence of four 3-week blocks. Ongoing, open stimulation was continued in consenting patients after the controlled trial. RESULTS: Patients tolerated DBS well. Dramatic benefits to mood, anxiety, and OCD symptoms were seen in one patient during blinded study and open, long-term follow-up. A second patient showed moderate benefit during open follow-up. CONCLUSIONS: It appears that DBS has potential value for treating refractory psychiatric disorders, but additional development work is needed before the procedure is utilized outside of carefully controlled research protocols.

Adult↗
PubMed2005

Matching geometry and stimulation parameters of electrodes for deep brain stimulation experiments--numerical considerations.

Deep brain stimulation, the electric stimulation of basal ganglia nuclei, is a treatment for movement disorders such as Parkinson's disease. The underlying mechanisms are studied in animals, e.g. rodents. Designs and materials of commercially available microelectrodes, as well as experimentally applied driving signals vary tremendously. We used finite integration modeling to compare the electric field and current density distributions induced by various electrodes. Current density or field strength "hot spots", which are located particularly at sites of high curvature and material interfaces coincided with corrosion and erosion at poles and insulation, respectively, as shown by scanning electron microscopy of stainless steel electrodes. Cell constants, i.e. geometry factors relating the electrode impedance to the specific medium conductivity, were calculated to determine the electrode voltage for a given stimulation current. Nevertheless, for electrodes of the same cell constant but of different geometry, current and field distributions may be very dissimilar. We found geometry-dependent limiting values of the stimulation current, above which electric tissue damage may occur. These values limit the reach of the stimulation signal for a given electrode geometry. Also, electrode geometries determine the shape of the stimulated tissue volume. This study provides tools for choosing the most appropriate geometry for targeting different-sized brain areas.

Animals↗
PubMed1982

Chronic cerebellar stimulation (CCS) and deep brain stimulation (DBS) in involuntary movement disorders.

Motor disorders of disinhibition may be modified by prosthetic mobilization of CNS inhibitory mechanisms by chronic electrical stimulation of the cerebellar cortex (CCS) and by deep brain stimulation of the thalamus and internal capsule (DBS). Reduction in spasticity, abnormal movements, intractable epilepsy and aggressive behavior has been reported after CCS, although negative results in human and animal studies have been published. No adverse neurologic, psychologic or intellectual effects of stimulation have occurred after 7 years of CCS, although subclinical histological changes may occur in the cerebellar cortex under the electrodes. CCS has been shown to produce physiological changes in evoked potentials, motoneurone excitability, epileptic discharges in the EEG and quantitative changes in movement. Surface and deep thalamic recordings have shown reduced amplitudes of somatosensory responses after CCS. Over the last 2 years we have employed chronic deep brain stimulation (DBS) in 49 patients with clinically useful results in half the patients. The technique allows reversible modification of movement disorders, and the technique can be used on the second side after a previous thalamectomy. Physiological testing, direct thalamic recordings and quantitative analysis of movement have allowed assessment of optimal rate and voltage of stimulation. For some intractable movement disorders DBS has effected significant therapeutic results when all other therapeutic techniques have failed.

Adolescent↗
PubMed2006

Experience with microelectrode guided subthalamic nucleus deep brain stimulation.

OBJECTIVE: Subthalamic deep brain stimulation (DBS) has rapidly become the standard surgical therapy for medically refractory Parkinson disease. However, in spite of its wide acceptance, there is considerable variability in the technical approach. This study details our technique and experience in performing microelectrode recording (MER) guided subthalamic nucleus (STN) DBS in the treatment of Parkinson disease. METHODS: Forty patients underwent surgery for the implantation of 70 STN DBS electrodes. Stereotactic localization was performed using a combination of magnetic resonance and computed tomographic imaging. We used an array of three microelectrodes, separated by 2 mm, for physiological localization of the STN. The final location was selected based on MER and macrostimulation through the DBS electrode. RESULTS: The trajectory selected for the DBS electrode had an average pass through the STN of 5.6 +/- 0.4 mm on the left and 5.7 +/- 0.4 mm on the right. The predicted location was used in 42% of the cases but was modified by MER in the remaining 58%. Patients were typically discharged on the second postoperative day. Eighty-five percent of patients were sent home, 13% required short-term rehabilitation, and one patient required long-term nursing services. Seven complications occurred over 4 years. Four patients suffered small hemorrhages, one patient experienced a lead migration, one developed an infection of the pulse generator, and one patient suffered from a superficial cranial infection. CONCLUSION: Simultaneous bilateral MER-guided subthalamic DBS is a relatively safe and well-tolerated procedure. MER plays an important role in optimal localization of the DBS electrodes.

Aged↗
PubMed2005

Error analysis of MRI and leksell stereotactic frame target localization in deep brain stimulation surgery.

Stereotactic deep brain stimulation (DBS) is the surgical treatment of choice for medication-refractory patients with Parkinson's disease and essential tremor. The subthalamic nucleus and ventral intermediate nucleus of the thalamus appear to be effective targets for electrode placement. Because these targets are small and encased in fiber tracts, their localization can be exceedingly difficult. However, the precision of electrode placement is crucial for obtaining successful results. Currently, surgeons rely on preoperative MRI or CT images to derive stereotactic coordinates for targeting sites such as the subthalamic nucleus and ventral intermediate nucleus of the thalamus coupled with microelectrode recordings during surgery for proper electrode placement. However, it has been argued that the stereotactic head frame produces detrimental artifacts during MRI. We examined MRI images taken from 11 patients undergoing repeat DBS surgery, and determined the coordinates of the previously placed electrode. We then set the Leksell G stereotactic frame to these coordinates and obtained fluoroscope-localizing images. Using MATLAB image analysis tools, we were able to quantify the 3-dimensional error in target localization by measuring the distance from the electrode tip to the targeted coordinate. The mean errors were 0.09 +/- 0.34 mm perpendicular, lateral to medial, 0.01 +/- 0.32 perpendicular, posterior to anterior, and -0.08 +/- 0.33 mm parallel to the electrode, superior to inferior. According to statistical analysis, the error was random and did not seem to move in any predictable fashion. Therefore, we conclude that preoperative MRI images can be safely used in DBS surgery, and they do not negatively affect its accuracy.

Aged↗
PubMed2005

Reliability of atlas-derived coordinates in deep brain stimulation.

BACKGROUND: In deep brain stimulation the way to define and localize the optimal target for the individual patient is still under debate. The objective of our study was to investigate the reliability of atlas derived data by comparing them with direct targeting on MR images. METHOD: We investigated 28 STN targets in 14 volunteers. The stereotactic coordinates of the dorso-lateral subthalamic nucleus (STN), were determined in 5 different ways for both STNs of each individual volunteer: 1. directly, on axial T2WI spin echo slices, 2. directly, on coronal T2WI spin echo slices and after fusion of data sets: 3. indirectly, on an axial atlas plate, 4. indirectly, on a coronal atlas plate, 5. indirectly, 12 mm lateral, 3 mm posterior and 3 mm inferior to mid-AC-PC. FINDINGS: The differences between MRI derived targets on axial vs. coronal slices were not statistically significant. After detection of the atlas derived targets the resulting x-coordinates were found more lateral than after direct detection on both, axial and coronal T2-weighted images (p < 0.001). On axial images y-coordinates were located more anterior (p = 0.240) on atlas derived targets and more posterior when target localizations were compared on coronal slices (p < 0.001). z-Coordinates were more superior after atlas targeting compared to MRI targeting (p < 0.001). Differences up to 6.21 mm occurred. CONCLUSIONS: Despite the limitations concerning image distortions and slice thickness, direct target planning on MRI, regarding our results, is more reliable than targeting solely based on atlas derived data. Only MRI gives us detailed information about the individual configurations of central structures in every single patient. However, targets, which are not detectable on MRI like the nucleus ventralis intermedius have to be planned using stereotactic atlas information. In these cases intra-operative micro-electrode recording might help to better define the target region.

Adult↗
PubMed2003

Mechanisms and the current state of deep brain stimulation in neuropsychiatry.

Deep brain stimulation (DBS) is established as a therapy for movement disorders, and it is an investigational treatment in other neurologic conditions. DBS precisely targets neuroanatomical targets deep within the brain that are proposed to be centrally involved in the pathophysiology of some neuropsychiatric illnesses. DBS is nonablative, offering the advantages of reversibility and adjustability. This might permit therapeutic effectiveness to be enhanced or side effects to be minimized. Preclinical and clinical studies have shown effects of DBS locally, at the stimulation target, and at a distance, via actions on fibers of passage or across synapses. Although its mechanisms of action are not fully elucidated, several effects have been proposed to underlie the therapeutic effects of DBS in movement disorders, and potentially in other conditions as well. The mechanisms of action of DBS are the focus of active investigation in a number of clinical and preclinical laboratories. As in severe movement disorders, DBS may offer a degree of hope for patients with intractable neuropsychiatric illness. It is already clear that research intended to realize this potential will require a very considerable commitment of resources, energy, and time across disciplines including psychiatry, neurosurgery neurology, neuropsychology, bioengineering, and bioethics. These investigations should proceed cautiously.

Electric Stimulation Therapy↗