Long-term results of ventrolateral thalamotomy for patients with Parkinson's disease.
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This study evaluated the long-term outcome for 53 patients with idiopathic Parkinson's disease treated by stereotactic thalamotomy between 1977 and 1996 at our institute. Significant reduction of tremor and rigidity of the contralateral extremities persisted throughout the follow-up period (mean 8.8 years) in 44 patients who underwent unilateral thalamotomy. These effects resulted in postoperative improvement of activity of daily life (ADL) with reduced dosage of levodopa. The effect of surgery on akinesia was limited and postoperative progression of akinesia was related to the postoperative deterioration of ADL. Multivariate analysis disclosed that the preoperative akinesia score was the critical factor for poor outcome. Nine patients underwent bilateral thalamotomies at a mean interval of 56 months. Five patients were obviously benefited from the second thalamotomy. The only perioperative complication was large intracerebral hematoma at the lesion site in one patient. This study confirmed the reliable and persistent effect of thalamotomy. Patients with Parkinson's disease whose disability is mainly caused by tremor and/or rigidity will be benefited from this procedure. Second thalamotomy, contralateral to the initial side, may be indicated if the ADL deteriorates due to the progression of the symptoms on the non-treated side. Patients disabled by advanced akinesia are not good candidates for thalamotomy. (+info)
Attachment device for side-biting cannula in stereotactic biopsy--technical note.
(18/816)
An attachment device to fix a Sedan side-biting biopsy cannula to a stereotactic frame is described. The disadvantages of the biopsy cup forceps are resolved, and a relatively large amount of multiple specimens can be obtained along a single biopsy trajectory. This attachment device enables the side-biting cannula to follow a straight trajectory biopsy in various stereotactic frames. (+info)
An H(2) (15)O-PET study of cerebral blood flow changes during focal epileptic discharges induced by intracerebral electrical stimulation.
(19/816)
Partial epileptic seizures are known to cause a focal increase in cerebral blood flow (CBF). However, quantified studies of ictal CBF changes under intracranial EEG control are still needed to assess the relationships in time and space between CBF changes and electrical discharges. Ten patients undergoing an intracerebral stereotaxic EEG (stereo-EEG) investigation for epilepsy surgery were prospectively studied for local perfusion changes. These were measured by H(2)(15)O-PET during 12 subclinical or mild symptomatic focal epileptic discharges induced by intracerebral electrical stimulation of the hippocampus (eight), amygdala (two), temporal pole (one) and fusiform gyrus (one). This study aimed to assess whether a significant focal blood flow change reflected the geographical extent of the underlying coincident epileptic discharge, as measured by this method at seizure onset. No significant CBF change was observed on test-retest at rest or during ineffective electrical stimulations outside the epileptogenic area. Compared with the resting condition, a significant focal perfusion increase of 16-55% occurred during eight discharges, there was no CBF change in three and a significant CBF decrease in one. Ictal CBF increases were mostly associated with low-voltage fast activity, but their magnitude had no obvious link with the duration of the discharge (range 8-106 s). Regional analysis of ictal PET was performed in 10 anatomical areas during each of the 12 discharges. Of all the 120 regions, 59 were not explored by intracerebral electrodes and 14 (24%) of these demonstrated ictal CBF changes. In 43 of the 61 regions explored by stereo-EEG (70.5%), PET and depth EEG findings converged, showing either a CBF change in a discharging area or no CBF change in a region unaffected by the discharge. Areas of increased CBF indicated an underlying epileptic discharge in almost 100% of the cases. Conversely, of the 18 regions showing discrepancies between intracerebral recordings and PET data, 17 were discharging regions showing no ictal CBF changes. Thus, a focal CBF increase, when detected at the seizure onset concomitantly with the initial low-voltage fast activity, was a reliable marker of an underlying epileptic discharge. It emphasizes the importance of injecting blood-flow tracers as soon as possible after detection of the discharge in routine clinical studies, even at a subclinical stage of the seizure. However, the extent of significant ictal CBF changes can be more restricted than that of the electrical discharge, thus limiting the reliability of ictal CBF images for outlining the contours of a tailored cortectomy. (+info)
The placement of lumbar pedicle screws using computerised stereotactic guidance.
(20/816)
Computer-assisted frameless stereotactic image guidance allows precise preoperative planning and intraoperative localisation of the image. It has been developed and tested in the laboratory. We evaluated the efficacy, clinical results and complications of placement of a pedicle screw in the lumbar spine using this technique. A total of 62 patients (28 men, 34 women) had lumbar decompression and spinal fusion with segmental pedicle screws. Postoperative CT scans were taken of 35 patients to investigate the placement of 330 screws. None showed penetration of the medial or inferior wall of a pedicle. Registration was carried out 66 times. The number of fiducial points used on each registration averaged 5.8 (4 to 7) The mean registration error was 0.75 mm (0.32 to 1.72). This technique provides a safe and reliable guide for placement of transpedicular screws in the lumbar spine. (+info)
An anatomical landmark for the supplementary eye fields in human revealed with functional magnetic resonance imaging.
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Together with the frontal and parietal eye fields, the supplementary eye field (SEF) is involved in the performance and control of voluntary and reflexive saccades and of ocular pursuit. This region was first described in non-human primates and is rather well localized on the dorsal surface of the medial frontal cortex. In humans the site of the SEF is still ill-defined. Functional imaging techniques have allowed investigation of the location and function of the SEF. However, there is great variability with regard to the published standardized coordinates of this area. We used here the spatial precision of functional magnetic resonance imaging (fMRI) in order to better localize the SEF in individuals. We identified as the SEF a region on the medial wall that was significantly activated when subjects executed self-paced horizontal saccades in darkness as compared to rest. This region appeared to be predominantly activated in the left hemisphere. We found that, despite a discrepancy of >2 cm found in the standardized Talairach coordinates, the location of this SEF-region could be precisely and reliably described by referring to a sulcal landmark found in each individual: the upper part of the paracentral sulcus. (+info)
Cranionavigator combining a high-speed drill and a navigation system for skull base surgery--technical note.
(22/816)
Drilling of the skull base bone without damaging the important inside structures and with the correct orientation is very difficult even with the help of the anatomical landmarks. Monitoring of the location and direction of the drill tip and indications of the removed part of the bone during the drilling procedure enhances safety and achieves less invasive neurosurgery. We have developed a novel cranionavigator by combining a high-speed drill with a neurosurgical navigation system. To reduce the positional error to less than 1.5 mm, the position sensor (magnetic field sensor) must be attached 5 cm from the metallic fan portion of the drill and the sensor kept at least 10 cm away from the operating microscope. Simulation studies with the cranionavigator using two dried skulls and three cadaver heads were performed before clinical application. Clinically, this surgical instrument was used in four patients with the skull base tumor. The cranionavigator helped to safely drill the skull base bone in a shorter time by dynamic and real-time display of the precise operating site and extent of bone drilling on the preoperative computed tomography scans or magnetic resonance images. The cranionavigator is a very helpful instrument for skull base surgery in the hands of neurosurgeons with extensive expertise and anatomical knowledge. (+info)
Neuropsychological outcome following unilateral pallidotomy.
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Despite the findings of significantly improved motor functioning following pallidotomy for the treatment of Parkinson's disease, the cognitive sequelae following surgery have yet to be clearly defined. With increasing knowledge of the surgery's effect on frontostriatal circuits, the cognitive processes potentially affected by the procedure require further exploration to evaluate fully the efficacy of the treatment. We reviewed 10 studies on the neuropsychological outcome after pallidotomy that were published in peer-reviewed journals. A general agreement exists that pallidotomy is a relatively safe and effective treatment for ameliorating the motor symptoms of Parkinson's disease, with relatively few cognitive changes reported following surgery. However, a number of conceptual and methodological concerns, including diverse selection criteria, small sample sizes and short follow-up periods, limit the interpretation and generalizability of these findings. These concerns are discussed in detail, along with a summary of the current neuropsychological literature, suggested guidelines for the conduct of research and future research directions. The neuropsychological findings are critically reviewed and tabulated by study, cognitive domain and follow-up period, with particular emphasis on hemisphere-specific cognitive changes. (+info)
Gustatory neuron types in rat geniculate ganglion.
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We used extracellular single-cell recording procedures to characterize the chemical and thermal sensitivity of the rat geniculate ganglion to lingual stimulation, and to examine the effects of specific ion transport antagonists on salt transduction mechanisms. Hierarchical cluster analysis of the responses from 73 single neurons to 3 salts (0.075 and 0.3 M NaCl, KCl, and NH(4) Cl), 0.5 M sucrose, 0.01 M HCl, and 0.02 M quinine HCl (QHCl) indicated 3 main groups that responded best to either sucrose, HCl, or NaCl. Eight narrowly tuned neurons were deemed sucrose-specialists and 33 broadly tuned neurons as HCl-generalists. The NaCl group contained three identifiable subclusters: 18 NaCl-specialists, 11 NaCl-generalists, and 3 QHCl-generalists. Sucrose- and NaCl-specialists responded specifically to sucrose and NaCl, respectively. All generalist neurons responded to salt, acid, and alkaloid stimuli to varying degree and order depending on neuron type. Response order was NaCl > HCl = QHCl > sucrose in NaCl-generalists, HCl > NaCl > QHCl > sucrose in HCl-generalists, and QHCl = NaCl = HCl > sucrose in QHCl-generalists. NaCl-specialists responded robustly to low and high NaCl concentrations, but weakly, if at all, to high KCl and NH(4) Cl concentrations after prolonged stimulation. HCl-generalist neurons responded to all three salts, but at twice the rate to NH(4) Cl than to NaCl and KCl. NaCl- and QHCl-generalists responded equally to the three salts. Amiloride and 5-(N,N-dimethyl)-amiloride (DMA), antagonists of Na(+) channels and Na(+)/H(+) exchangers, respectively, inhibited the responses to 0.075 M NaCl only in NaCl-specialist neurons. The K(+) channel antagonist, 4-aminopyridine (4-AP), was without a suppressive effect on salt responses, but, when applied alone in solution, it evoked a response in many HCl-generalists and one QHCl-generalist neuron so tested. Of the 39 neurons tested for their sensitivity to temperature, 23 responded to cooling and chemical stimulation, and 20 of these neurons were HCl-generalists. Moreover, the responses to the four standard stimuli were reduced progressively at lower temperatures in HCl- and QHCl-generalist neurons, but not in NaCl-specialists. Thus sodium channels and Na(+)/H(+) exchangers appear to be expressed exclusively on the membranes of receptor cells that synapse with NaCl-specialist neurons. In addition, cooling sensitivity and taste-temperature interactions appear to be prominent features of broadly tuned neuron groups, particularly HCl-generalists. Taken all together, it appears that lingual taste cells make specific connections with afferent fibers that allow gustatory stimuli to be parceled into different input pathways. In general, these neurons are organized physiologically into specialist and generalist types. The sucrose- and NaCl-specialists alone can provide sufficient information to distinguish sucrose and NaCl from other stimuli, respectively. (+info)