Thalamic stimulation and functional magnetic resonance imaging: localization of cortical and subcortical activation with implanted electrodes

1999 ◽  
Vol 90 (3) ◽  
pp. 583-590 ◽  
Author(s):  
Ali R. Rezai ◽  
Andres M. Lozano ◽  
Adrian P. Crawley ◽  
Michael L. G. Joy ◽  
Karen D. Davis ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Mr Imaging ◽  
Somatosensory Cortex ◽  
Clinical Effects ◽  
Functional Magnetic Resonance ◽  
Electrode Implantation ◽  
Content Type ◽  
Functional Mr Imaging ◽  
Fine Print ◽  
Deep Brain

✓ The utility of functional magnetic resonance (fMR) imaging in patients with implanted thalamic electrodes has not yet been determined. The aim of this study was to establish the safety of performing fMR imaging in patients with thalamic deep brain stimulators and to determine the value of fMR imaging in detecting cortical and subcortical activity during stimulation.Functional MR imaging was performed in three patients suffering from chronic pain and two patients with essential tremor. Two of the three patients with pain had undergone electrode implantation in the thalamic sensory ventralis caudalis (Vc) nucleus and the other had undergone electrode implantation in both the Vc and the periventricular gray (PVG) matter. Patients with tremor underwent electrode implantation in the ventralis intermedius (Vim) nucleus. Functional MR imaging was performed during stimulation by using a pulse generator connected to a transcutaneous extension lead. Clinically, Vc stimulation evoked paresthesias in the contralateral body, PVG stimulation evoked a sensation of diffuse internal body warmth, and Vim stimulation caused tremor arrest.Functional images were acquired using a 1.5-tesla MR imaging system. The Vc stimulation at intensities provoking paresthesias resulted in activation of the primary somatosensory cortex (SI). Stimulation at subthreshold intensities failed to activate the SI. Additional stimulation-coupled activation was observed in the thalamus, the secondary somatosensory cortex (SII), and the insula. In contrast, stimulation of the PVG electrode did not evoke paresthesias or activate the SI, but resulted in medial thalamic and cingulate cortex activation. Stimulation in the Vim resulted in thalamic, basal ganglia, and SI activation.An evaluation of the safety of the procedure indicated that significant current could be induced within the electrode if a faulty connecting cable (defective insulation) came in contact with the patient. Simple precautions, such as inspection of wires for fraying and prevention of their contact with the patient, enabled the procedure to be conducted safely. Clinical safety was further corroborated by performing 86 MR studies in patients in whom electrodes had been implanted with no adverse clinical effects.This is the first report of the use of fMR imaging during stimulation with implanted thalamic electrodes. The authors' findings demonstrate that fMR imaging can safely detect the activation of cortical and subcortical neuronal pathways during stimulation and that stimulation does not interfere with imaging. This approach offers great potential for understanding the mechanisms of action of deep brain stimulation and those underlying pain and tremor generation.

Thalamic stimulation and functional magnetic resonance imaging: localization of cortical and subcortical activation with implanted electrodes

1999 ◽  
Vol 6 (3) ◽  
pp. E4
Author(s):  
Ali R. Rezai ◽  
Andres M. Lozano ◽  
Adrian P. Crawley ◽  
Michael L. G. Joy ◽  
Karen D. Davis ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Mr Imaging ◽  
Somatosensory Cortex ◽  
Pulse Generator ◽  
Imaging System ◽  
Clinical Effects ◽  
Functional Magnetic Resonance ◽  
Electrode Implantation ◽  
Functional Mr Imaging ◽  
Deep Brain

The utility of functional magnetic resonance (fMR) imaging in patients with implanted thalamic electrodes has not yet been determined. The aim of this study was to establish the safety of performing fMR imaging in patients with thalamic deep brain stimulators and to determine the value of fMR imaging in detecting cortical and subcortical activity during stimulation. Functional MR imaging was performed in three patients suffering from chronic pain and two patients with essential tremor. Two of the three patients with pain had undergone electrode implantation in the thalamic sensory ventralis caudalis (Vc) nucleus and the other had undergone electrode implantation in both the Vc and the periventricular gray (PVG) matter. Patients with tremor underwent electrode implantation in the ventralis intermedius (Vim) nucleus. Functional MR imaging was performed during stimulation by using a pulse generator connected to a transcutaneous extension lead. Clinically, Vc stimulation evoked paresthesias in the contralateral body, PVG stimulation evoked a sensation of diffuse internal body warmth, and Vim stimulation caused tremor arrest. Functional images were acquired using a 1.5-tesla MR imaging system. The Vc stimulation at intensities provoking paresthesias resulted in activation of the primary somatosensory cortex (SI). Stimulation at subthreshold intensities failed to activate the SI. Additional stimulation-coupled activation was observed in the thalamus, the secondary somatosensory cortex (SII), and the insula. In contrast, stimulation of the PVG electrode did not evoke paresthesias or activate the SI, but resulted in medial thalamic and cingulate cortex activation. Stimulation in the Vim resulted in thalamic, basal ganglia, and SI activation. An evaluation of the safety of the procedure indicated that significant current could be induced within the electrode if a faulty connecting cable (defective insulation) came in contact with the patient. Simple precautions, such as inspection of wires for fraying and prevention of their contact with the patient, enabled the procedure to be conducted safely. Clinical safety was further corroborated by performing 86 MR studies in patients in whom electrodes had been implanted with no adverse clinical effects. This is the first report of the use of fMR imaging during stimulation with implanted thalamic electrodes. The authors' findings demonstrate that fMR imaging can safely detect the activation of cortical and subcortical neuronal pathways during stimulation and that stimulation does not interfere with imaging. This approach offers great potential for understanding the mechanisms of action of deep brain stimulation and those underlying pain and tremor generation.

Magnetic resonance imaging stereotactic target localization for deep brain stimulation in dystonic children

2000 ◽  
Vol 93 (5) ◽  
pp. 784-790 ◽  
Author(s):  
Nathalie Vayssiere ◽  
Simone Hemm ◽  
Michel Zanca ◽  
Marie Christine Picot ◽  
Alain Bonafe ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
Magnetic Resonance ◽  
Mr Imaging ◽  
General Anesthesia ◽  
Brain Stimulation ◽  
Target Localization ◽  
Electrode Implantation ◽  
Content Type ◽  
Fine Print ◽  
Deep Brain

Object. The actual distortion present in a given series of magnetic resonance (MR) images is difficult to establish. The purpose of this study was to validate an MR imaging—based methodology for stereotactic targeting of the internal globus pallidus during electrode implantation in children in whom general anesthesia had been induced.Methods. Twelve children (mean follow up 1 year) suffering from generalized dystonia were treated with deep brain stimulation by using a head frame and MR imaging. To analyze the influence of distortions at every step of the procedure, the geometrical characteristics of the frame were first controlled using the localizer as a phantom. Then pre- and postoperative coordinates of fixed anatomical landmarks and electrode positions, both determined with the head frame in place, were statistically compared.No significant difference was observed between theoretical and measured dimensions of the localizer (Student's t-test, |t| > 2.2 for 12 patients) in the x, y, and z directions.No significant differences were observed (Wilcoxon paired-sample test) between the following: 1) pre- and postoperative coordinates of the anterior commissure (AC) (Δx = 0.3 ± 0.29 mm and Δy = 0.34 ± 0.32 mm) and posterior commissure (PC) (Δx = 0.15 ± 0.18 mm and Δy = 0.34 ± 0.25 mm); 2) pre- and postoperative AC—PC distance (ΔL = 0.33 ± 0.22 mm); and 3) preoperative target and final electrode position coordinates (Δx = 0.24 ± 0.22 mm; Δy = 0.19 ± 0.16 mm).Conclusions. In the authors' center, MR imaging distortions did not induce detectable errors during stereotactic surgery in dystonic children. Target localization and electrode implantation could be achieved using MR imaging alone after induction of general anesthesia. The remarkable postoperative improvement in these patients confirmed the accuracy of the procedure (Burke—Marsden—Fahn Dystonia Rating Scale score Δ = −83.8%).

Functional magnetic resonance imaging of sensory and motor cortex: comparison with electrophysiological localization

1995 ◽  
Vol 83 (2) ◽  
pp. 262-270 ◽  
Author(s):  
Aina Puce ◽  
R. Todd Constable ◽  
Marie L. Luby ◽  
Gregory McCarthy ◽  
Anna C. Nobre ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Magnetic Resonance ◽  
Motor Cortex ◽  
Mr Imaging ◽  
Sensorimotor Cortex ◽  
Functional Magnetic Resonance ◽  
Planar Imaging ◽  
Content Type ◽  
Functional Mr Imaging ◽  
Fine Print

✓ Functional magnetic resonance (MR) imaging was performed using a 1.5-tesla MR system to localize sensorimotor cortex. Six neurologically normal subjects were studied by means of axial gradient-echo images with a motor task and one or more sensory tasks: 1) electrical stimulation of the median nerve; 2) continuous brushing over the thenar region; and 3) pulsed flow of compressed air over the palm and digits. An increased MR signal was observed in or near the central sulcus, consistent with the location of primary sensory and motor cortex. Four patients were studied using echo planar imaging sequences and motor and sensory tasks. Three patients had focal refractory seizures secondary to a lesion impinging on sensorimotor cortex. Activation seen on functional MR imaging was coextensive with the location of the sensorimotor area determined by evoked potentials and electrical stimulation. Functional MR imaging provides a useful noninvasive method of localization and functional assessment of sensorimotor cortex.

Early changes measured by magnetic resonance imaging in cerebral blood flow, blood volume, and blood-brain barrier permeability following dexamethasone treatment in patients with brain tumors

1999 ◽  
Vol 90 (2) ◽  
pp. 300-305 ◽  
Author(s):  
Leif Østergaard ◽  
Fred H. Hochberg ◽  
James D. Rabinov ◽  
A. Gregory Sorensen ◽  
Michael Lev ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Magnetic Resonance ◽  
Brain Tumors ◽  
Mr Imaging ◽  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Clinical Effects ◽  
Content Type ◽  
Fine Print

Object. In this study the authors assessed the early changes in brain tumor physiology associated with glucocorticoid administration. Glucocorticoids have a dramatic effect on symptoms in patients with brain tumors over a time scale ranging from minutes to a few hours. Previous studies have indicated that glucocorticoids may act either by decreasing cerebral blood volume (CBV) or blood-tumor barrier (BTB) permeability and thereby the degree of vasogenic edema.Methods. Using magnetic resonance (MR) imaging, the authors examined the acute changes in CBV, cerebral blood flow (CBF), and BTB permeability to gadolinium-diethylenetriamine pentaacetic acid after administration of dexamethasone in six patients with brain tumors. In patients with acute decreases in BTB permeability after dexamethasone administration, changes in the degree of edema were assessed using the apparent diffusion coefficient of water.Conclusions. Dexamethasone was found to cause a dramatic decrease in BTB permeability and regional CBV but no significant changes in CBF or the degree of edema. The authors found that MR imaging provides a powerful tool for investigating the pathophysiological changes associated with the clinical effects of glucocorticoids.

Transient dystonia following magnetic resonance imaging in a patient with deep brain stimulation electrodes for the treatment of Parkinson disease

2003 ◽  
Vol 99 (4) ◽  
pp. 772-774 ◽  
Author(s):  
Jörg Spiegel ◽  
Gerhard Fuss ◽  
Martin Backens ◽  
Wolfgang Reith ◽  
Tim Magnus ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Deep Brain Stimulation ◽  
Magnetic Resonance ◽  
Mr Imaging ◽  
Parkinson Disease ◽  
Resonance Imaging ◽  
Content Type ◽  
Ballistic Movements ◽  
Fine Print ◽  
Deep Brain

✓ Data from previous studies have shown that magnetic resonance (MR) imaging of the head can be performed safely in patients with deep brain stimulators. The authors report on a 73-year-old patient with bilaterally implanted deep brain electrodes for the treatment of Parkinson disease, who exhibited dystonic and partially ballistic movements of the left leg immediately after an MR imaging session. Such dystonic or ballistic movements had not been previously observed in this patient. In the following months, this focal movement disorder resolved completely. This case demonstrates the possible risks of MR imaging in patients with deep brain stimulators.

Comparison of atlas- and magnetic resonance imaging—based stereotactic targeting of the globus pallidus internus in the performance of deep brain stimulation for the treatment of dystonia

2002 ◽  
Vol 96 (4) ◽  
pp. 673-679 ◽  
Author(s):  
Nathalie Vayssiere ◽  
Simone Hemm ◽  
Laura Cif ◽  
Marie Christine Picot ◽  
Nina Diakonova ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Deep Brain Stimulation ◽  
Magnetic Resonance ◽  
Mr Imaging ◽  
Resonance Imaging ◽  
Mr Images ◽  
Content Type ◽  
Significant Difference ◽  
Fine Print ◽  
Deep Brain

Object. To assess the validity of relying on atlases during stereotactic neurosurgery, the authors compared target coordinates in the globus pallidus internus (GPi) obtained using magnetic resonance (MR) imaging with those determined using an atlas. The targets were used in deep brain stimulation (DBS) for the treatment of generalized dystonia. Methods. Thirty-five patients, who were treated using bilateral DBS of the GPi, were included in this study. The target was selected on three-dimensional MR images by direct visual recognition of the GPi. The coordinates were automatically recorded using dedicated software. They were translated into the anterior commissure—posterior commissure (AC—PC) coordinate system by using a matrix transformation process. The same GPi target was defined, based on the locations of brain structures shown in the atlases of Schaltenbrand and Talairach. Magnetic resonance imaging—based GPi target coordinates were statistically compared with the corresponding atlas-based coordinates by applying the Student t-test. A significant difference (p < 0.001) was demonstrated in x, y, and z directions between MR imaging—based and Schaltenbrand atlas—derived target coordinates. The comparison with normalized Talairach atlas coordinates demonstrated a significant difference (p < 0.01) in the y and z directions, although not in the x direction (p = 0.12). No significant correlation existed between MR imaging—based target coordinates and patient age (p > 0.1). No significant correlation was observed between MR imaging—based target coordinates and patient sex in the y and z directions (p > 0.9), although it was significant in the x direction (p < 0.05). A significant variation in coordinates and the length of the AC—PC line was revealed only in the y direction (p < 0.005). Conclusions. A significant difference was found between target coordinates obtained by direct visual targeting on MR images (validated by postoperative clinical results) and those obtained by indirect targeting based on atlases.

Loss of sensory discrimination after median nerve injury and activation in the primary somatosensory cortex on functional magnetic resonance imaging

2003 ◽  
Vol 99 (1) ◽  
pp. 100-105 ◽  
Author(s):  
Thomas Hansson ◽  
Tom Brismar
Keyword(s):  
Magnetic Resonance ◽  
Median Nerve ◽  
Somatosensory Cortex ◽  
Nerve Injury ◽  
Tactile Stimulation ◽  
Functional Magnetic Resonance ◽  
Content Type ◽  
Sensory Discrimination ◽  
Median Nerve Injury ◽  
Fine Print

Object. The aim of this study was to assess the effects of median nerve injury and regeneration on neuronal activation in the somatosensory cortex by means of functional magnetic resonance (fMR) imaging and somatosensory evoked potentials (SSEPs). Methods. Ten injured male patients (mean age 26 years) were examined 15 to 58 months after a total transection of the median nerve at the wrist that was repaired with epineural sutures. Two-point discrimination was lost in Digit II–III and sensory nerve conduction displayed decreased velocity (−29%) and amplitude (−84%) in the median nerve at the wrist. The fMR images were obtained during tactile stimulation (gentle strokes) performed separately on the volar surface of either Digit II–III or Digit IV–V (eight patients: two were excluded because of movement artifacts). The SSEPs were obtained using electrical stimulation proximal to the median nerve lesion. Conclusions. Patients with loss of sensory discrimination after median nerve damage and regeneration had larger areas of activation in fMR imaging near the contralateral central sulcus during tactile stimulation of the injured compared with the noninjured hand. The increase relative to the unaffected hand was 43% (p < 0.02) for Digit II–III stimulation and 46% (p < 0.02) for Digit IV–V stimulation. The SSEP data showed normal latency and amplitude. The enlarged area of cortical activation may be the result of reorganization, and it may indicate that larger cortical areas are involved in the discriminatory task after a derangement of the peripheral input.

Accelerated spondylotic changes adjacent to the fused segment following central cervical corpectomy: magnetic resonance imaging study evidence

2004 ◽  
Vol 100 (1) ◽  
pp. 2-6 ◽  
Author(s):  
Vaijayantee Kulkarni ◽  
Vedantam Rajshekhar ◽  
Lakshminarayan Raghuram
Keyword(s):  
Magnetic Resonance ◽  
Mr Imaging ◽  
Imaging Study ◽  
Degenerative Changes ◽  
Adjacent Segment ◽  
Mr Images ◽  
Short Term ◽  
Content Type ◽  
Fine Print

Object. The authors studied whether cervical spine motion segments adjacent to a fused segment exhibit accelerated degenerative changes on short-term follow-up magnetic resonance (MR) imaging. Methods. Preoperative and short-term follow-up (mean duration 17.5 months, range 10–48 months) cervical MR images obtained in 44 patients who had undergone one- or two-level corpectomy for cervical spondylotic myelopathy were evaluated qualitatively and quantitatively. The motion segment adjacent to the fused segment and a segment remote from the fused segment were evaluated for indentation of the thecal sac, disc height, and sagittal functional diameter of the spinal canal on midsagittal T2-weighted MR images. Thecal sac indentations were classifed as mild, moderate, and severe. New indentations of the thecal sac of varying severity (mild in 17 patients [38.6%], moderate in 10 [22.7%], and severe in six [13.6%]) had developed at the adjacent segments in 33 (75%) of 44 patients. The degenerative changes were seen at the superior level in 11 patients, inferior level in 10 patients, and at both levels in 12 patients and resulted from both anterior and posterior element degeneration in the majority (23 [69.6%]) of patients. The remote segments showed mild thecal sac indentations in seven patients and moderate indentations in two patients (nine [20.5%] of 44). Compared with the changes at the remote segment, the canal size was significantly decreased at the superior adjacent segment by 0.9 mm (p = 0.007). No patient sustained a new neurological deficit due to adjacent-segment changes. Conclusions. On short-term follow-up MR imaging, levels adjacent to the fused segment exhibited more pronounced degenerative changes (compared with remote levels) in 75% of patients who had undergone one- or two-level central corpectomy.

Lack of agreement between direct magnetic resonance imaging and statistical determination of a subthalamic target: the role of electrophysiological guidance

2002 ◽  
Vol 97 (3) ◽  
pp. 591-597 ◽  
Author(s):  
Emmanuel Cuny ◽  
Dominique Guehl ◽  
Pierre Burbaud ◽  
Christian Gross ◽  
Vincent Dousset ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Mr Imaging ◽  
Functional Response ◽  
Anterior Commissure ◽  
Surgical Techniques ◽  
High Frequency Stimulation ◽  
Mr Images ◽  
Posterior Commissure ◽  
Content Type ◽  
Fine Print

Object. The goal of this study was to determine the most suitable procedure(s) to localize the optimal site for high-frequency stimulation of the subthalamic nucleus (STN) for the treatment of advanced Parkinson disease. Methods. Stereotactic coordinates of the STN were determined in 14 patients by using three different methods: direct identification of the STN on coronal and axial T2-weighted magnetic resonance (MR) images and indirect targeting in which the STN coordinates are referred to the anterior commissure—posterior commissure (AC—PC) line, which, itself, is determined either by using stereotactic ventriculography or reconstruction from three-dimensional (3D) MR images. During the surgical procedure, electrode implantation was guided by single-unit microrecordings on multiple parallel trajectories and by clinical assessment of stimulations. The site where the optimal functional response was obtained was considered to be the best target. Computerized tomography scanning was performed 3 days later and the scans were combined with preoperative 3D MR images to transfer the position of the best target to the same system of stereotactic coordinates. An algorithm was designed to convert individual stereotactic coordinates into an all-purpose PC-referenced system for comparing the respective accuracy of each method of targeting, according to the position of the best target. Conclusions. The target that is directly identified by MR imaging is more remote (mainly in the lateral axis) from the site of the optimal functional response than targets obtained using other procedures, and the variability of this method in the lateral and superoinferior axes is greater. In contrast, the target defined by 3D MR imaging is closest to the target of optimal functional response and the variability of this method is the least great. Thus, 3D reconstruction adjusted to the AC—PC line is the most accurate technique for STN targeting, whereas direct visualization of the STN on MR images is the least effective. Electrophysiological guidance makes it possible to correct the inherent inaccuracy of the imaging and surgical techniques and is not designed to modify the initial targeting.

Physiological support and monitoring of critically ill patients during magnetic resonance imaging

1988 ◽  
Vol 68 (2) ◽  
pp. 246-250 ◽  
Author(s):  
Gene H. Barnett ◽  
Allan H. Ropper ◽  
Keith A. Johnson
Keyword(s):  
Magnetic Resonance ◽  
Mr Imaging ◽  
Critically Ill ◽  
Resonance Imaging ◽  
Monitoring Equipment ◽  
Mr Image ◽  
Content Type ◽  
Neurological Patients ◽  
Fine Print ◽  
Electrical Interference

✓ Magnetic resonance (MR) imaging has been largely restricted to patients who are neurologically and hemodynamically stable. The strong magnetic field and radiofrequency transmissions involved in acquiring images are potential sources of interference with monitoring equipment. A method of support and physiological monitoring of critically ill neurosurgical and neurological patients during MR imaging using a 0.6-tesla MR system is reported. This technique has not caused degradation of the MR image due to electrical interference. Adequate preparation and precautions allow many critically ill neurosurgical and neurological patients to safely undergo MR imaging.

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