Intraoperative microrecordings of the subthalamic nucleus in Parkinson's disease.

Microelectrode recordings of single unit neuronal activity were used during stereotactic surgery to define the subthalamic nucleus for chronic deep brain stimulation in the treatment of Parkinson's disease. By using five parallel trajectories, often two to three microelectrodes allow us to recognize subthalamic nucleus (STN) neuronal activity. STN neurons were easily distinguished from cells of the overlying zona incerta and the underlying substantia nigra.

Imaging of subthalamic nucleus and ventralis intermedius of the thalamus.

The techniques of targeting the subthalamic nucleus (STN) and the ventralis intermedius nucleus (Vim) are similar, only the coordinates are different. Targeting ideally consists of gathering all data about a target and positioning the electrode correctly within that target. The electrode should be positioned within a statistical range of coordinates, where the neuronal firing fits a given pattern and responds to external stimuli, particularly to proprioceptive inputs, in a somatotopically organized manner.

Results of deep brain stimulation for dystonia: a critical reappraisal.

Deep brain stimulation for severe dystonia is still in the very first stage of development. Only single case reports or small case series have been reported to date. Best results have been obtained with pallidal stimulation in patients with primary generalised dystonia, especially in DYT1 mutation carriers.

Treatment results: Parkinson's disease.

Deep brain stimulation (DBS) is a neurosurgical treatment of Parkinson's disease that is applied to three targets: the ventral intermediate nucleus of the thalamus (Vim), the globus pallidus internas (GPi) and the subthalamic nucleus (STN). Vim DBS mainly improves contralateral tremor and, therefore, is being supplanted by DBS of the two other targets, even in patients with tremor dominant disease. STN and GPi DBS improve off-motor phases and dyskinesias.

Mechanisms of deep brain stimulation.

The mechanism of action of high frequency deep brain stimulation is still unknown. However, in all circumstances and in all target nuclei so far stimulated, the effects mimic those of lesions previously made during thalamotomies, pallidotomies or even subthalamotomies, suggesting an inhibition of at least the neuronal network containing the target, if not of the target itself. On the contrary, fiber bundles are consistently activated at low or high frequencies.

Mirthful laughter induced by subthalamic nucleus stimulation.

High-frequency stimulation of the subthalamic nucleus (STN) improves the motor signs of Parkinson's disease (PD). The three main components (motor, associative, and limbic) of the cortical-basal ganglia-cortical circuits pass through the STN. It is not known whether STN stimulation can influence the limbic loop.

Altered metabolite concentrations with amiodarone generic substitution cannot be observed without monitoring.

The use of amiodarone has grown rapidly, resulting in the marketing of several generic formulations. The adequacy of the testing used to approve these formulations as bioequivalent has been questioned, and mounting clinical evidence suggests that in some patients, substitution with generic amiodarone can cause serious problems. The effects of switching amiodarone formulations may take weeks to develop, leaving the relationship between the events unrecognized.

Sertraline-induced hypoglycemia.

Objective: To report a case of hypoglycemia that occurred in a patient treated with the selective serotonin-reuptake inhibitor, sertraline.

Case Summary: An 82-year-old white woman with mild cardiovascular disease and no history of glucose intolerance was seen in the emergency department for a presyncopal episode associated with a blood glucose of 32 mg/dL as measured by the ambulance attendant. She had similar symptoms the day before.

Deep brain stimulation of the corpus luysi (subthalamic nucleus) and other targets in Parkinson's disease. Extension to new indications such as dystonia and epilepsy.

Chronic high frequency (130 Hz) stimulation (HFS) of the thalamic target Vim, first used in our group in 1987 as a treatment of tremor of various origins, has been used over the last ten years in 137 patients. Since 1993, this method has been extended to two other targets (subthalamic nucleus (STN): 137 patients and the medial pallidum (GPi): 12 patients), based on recent experimental data in rats and monkeys. STN appears to be a target of major interest, able to control the three cardinal symptoms and to allow the decrease or suppression of levodopa treatment, which then also suppresses levodopa induced dyskinesias.

Clinical characteristics and topography of lesions in movement disorders due to thalamic lesions.

Objective: To determine which thalamic subnuclei are involved in symptomatic unilateral movement disorders due to localized thalamic infarction, and the clinical characteristics of these abnormal movements.

Methods: The authors studied 22 patients with thalamic infarcts for their clinical presentation and the topography of the lesions, using three-dimensional T1-weighted MRI sequencing and stereotaxic analysis of the lesions.

Results: Patients were divided into four groups: 1) absence of abnormal involuntary movements (AIM) (nine patients); 2) isolated dystonic posture (two patients); 3) myoclonic dystonia (five patients); and 4) tremor or myoclonus (six patients).

Deep brain stimulation in the treatment of severe dystonia.

A retrospective study of a consecutive series of 19 patients with medically intractable dystonia treated with uni- or bilateral deep brain stimulation (DBS) is reported. A minimal follow-up of 6 months was available, up to eleven years in one patient. The first twelve consecutive patients (4 with primary and 8 with secondary dystonia) were treated with chronic stimulation of the posterior part of the ventrolateral thalamic nucleus (VLp).

Effect of bilateral stimulation of the subthalamic nucleus on parkinsonian voice.

The purpose of this study was to assess several acoustic features of the voices of 26 parkinsonian patients under two conditions, with and without bilateral chronic stimulation of the subthalamic nucleus (STN) to estimate the effectiveness of this procedure on parkinsonian speech. When compared to unstimulated patients, stimulated patients showed longer duration of sustained vowels, shorter duration of sentences, nonsense words, and pauses, more variable fundamental frequency (f0) in sentences, and more stable f0 during sustained vowels. Relative intensity was unchanged in both conditions.

Intermuscular coherence in Parkinson's disease: relationship to bradykinesia.

We hypothesised that bradykinesia may be partly due to the failure of the corticomuscular system to engage in high frequency oscillatory activity in Parkinson's disease (PD). In healthy subjects such oscillations are evident in coherence between active muscles at 15--30 Hz. We therefore investigated the effects of therapeutic stimulation of the basal ganglia on this coherence and related it to changes in bradykinesia in the contralateral arm.

Effect of bilateral subthalamic nucleus stimulation on gait in Parkinson's disease.

The fundamental disturbance of the parkinsonian gait is the reduction in walking velocity. This is mainly due to reduction in stride length, while cadence (steps/min) is slightly enhanced. Treatment with L-dopa increases stride length while cadence is unchanged.

Intermuscular coherence in Parkinson's disease: effects of subthalamic nucleus stimulation.

It remains unclear how high frequency stimulation of the subthalamic nucleus (STN) improves parkinsonism. We hypothesized that stimulation may affect the organization of the cortical drive to voluntarily activated muscle. Normally this is characterized by oscillations at 15-30 Hz, manifest in coherence between muscles in the same frequency band.

Consensus statement on the role of acute dopaminergic challenge in Parkinson's disease.

Available evidence on the practice of acute pharmacological challenge tests in parkinsonian patients was reviewed by a committee of experts, which achieved a general consensus. The published data deal mainly with the acute administration of levodopa and apomorphine in Parkinson's disease. Such challenge may serve different purposes, e.

Deep brain stimulation of the subthalamic nucleus for Parkinson's disease: methodologic aspects and clinical criteria.

The technique of deep brain stimulation (DBS) for the treatment of Parkinson's disease (PD) is evolving very rapidly. The subthalamic nucleus (STN) has become the preferred target in the past few years since our group demonstrated that high-frequency stimulation in this nucleus improves all cardinal features of PD, including resting tremor. This benefit in the parkinsonian symptoms allows a drastic reduction in daily levodopa requirements.

Deep brain stimulation of the globus pallidus pars interna in advanced Parkinson's disease.

Pallidotomy is now widely performed for the treatment of advanced Parkinson's disease (PD). Preliminary reports of the effect of globus pallidus pars interna deep brain stimulation (GPi DBS) have also been promising. We have analyzed a cohort of 22 consecutive patients enrolled in a multicenter study.

Origin of the mutations in the parkin gene in Europe: exon rearrangements are independent recurrent events, whereas point mutations may result from Founder effects.

A wide variety of mutations in the parkin gene, including exon deletions and duplications, as well as point mutations, result in autosomal recessive early-onset parkinsonism. Interestingly, several of these anomalies were found repeatedly in unrelated patients and may therefore result from recurrent, de novo mutational events or from founder effects. In the present study, haplotype analysis, using 10 microsatellite markers covering a 4.

Subthalamic nucleus, sensorimotor cortex and muscle interrelationships in Parkinson's disease.

Ten patients with Parkinson's disease were seen following bilateral or unilateral implantation of macroelectrodes into the subthalamic nucleus. Local field potentials (LFPs) were recorded from adjacent subthalamic nucleus macroelectrode (STNME) contacts simultaneously with EEG activity over the supplementary motor (Cz-FCz) and sensorimotor (C3/4-FC3/4) areas and EMG activity from the contralateral wrist extensors during isometric and phasic wrist movements. Significant coherence was seen between STNME LFPs and Cz-FCz, STNME LFPs and C3/4-FC3/4, and STNME LFPs and EMG over the range 7-45 Hz.

Effect of subthalamic nucleus stimulation on levodopa-induced dyskinesia in Parkinson's disease.

Article abstract-The authors studied the effect of bilateral subthalamic nucleus stimulation on levodopa-induced dyskinesias in 24 consecutive parkinsonian patients with disabling dyskinesias. The improvement in the three subtypes of levodopa-induced dyskinesias was significant from the third postoperative month and was mainly due to the decrease in the daily dose of levodopa allowed by the stimulation-induced improvement in the motor score.