Frequency-specific effects of stimulation of the subthalamic area in treated Parkinson's disease patients.

It has been hypothesized that too much synchronization in the beta band in basal ganglia-cortical circuits can contribute to bradykinesia and too little can contribute to hyperkinesia. The former has been supported by experiments in patients with Parkinson's disease and chronic implantation of the subthalamic area for deep brain stimulation. Stimulation at 20 Hz in this region slows voluntary tapping when performed in patients withdrawn from their usual antiparkinsonian medication.

HLA class II polymorphism in children with coeliac disease in Tunisia: is there any influence on clinical manifestation?

Objective: To elucidate the HLA DRB1, DQB1 and DQA1 polymorphism in Tunisian children with typical form of coeliac disease (CD) in comparison with those from mass screening (atypical and silent CD).

Materials And Methods: We recruited three groups: group I: 40 CD children diagnosed according to the ESPGHAN criteria. group II: 40 healthy controls matched with sex, age and geographic origin.

Avoiding the ventricle: a simple step to improve accuracy of anatomical targeting during deep brain stimulation.

Object: The authors examined the accuracy of anatomical targeting during electrode implantation for deep brain stimulation in functional neurosurgical procedures. Special attention was focused on the impact that ventricular involvement of the electrode trajectory had on targeting accuracy.

Methods: The targeting error during electrode placement was assessed in 162 electrodes implanted in 109 patients at 2 centers.

Sternal cleft, a rare congenital anomaly. Report of the first Tunisian case.

Background: Sternal cleft is an uncommon visually dramatic congenital anomaly of the chest wall. It is resulting of failure of the two lateral mesodermal sternal bars fusion by the eight weeks of gestation. Superior defects are the commonest forms, usually isolated.

The development of personalised cognitive prosthetics.

Persons suffering from mild dementia can benefit from a form of cognitive prosthetic which can be used to assist them with their day to day activities. Within our current work we are aiming to develop a successful user-validated cognitive prosthetic for persons with mild dementia. We have devised a three phased waterfall methodology to support our developments.

Method for patient-specific finite element modeling and simulation of deep brain stimulation.

Deep brain stimulation (DBS) is an established treatment for Parkinson's disease. Success of DBS is highly dependent on electrode location and electrical parameter settings. The aim of this study was to develop a general method for setting up patient-specific 3D computer models of DBS, based on magnetic resonance images, and to demonstrate the use of such models for assessing the position of the electrode contacts and the distribution of the electric field in relation to individual patient anatomy.

Effects of contact location and voltage amplitude on speech and movement in bilateral subthalamic nucleus deep brain stimulation.

Subthalamic nucleus deep brain stimulation (STN-DBS) is particularly effective in improving limb symptoms in Parkinson's disease. However, speech shows a variable response. Contact site and amplitude of stimulation have been suggested as possible factors influencing speech.

High-frequency stimulation of the subthalamic nucleus suppresses oscillatory beta activity in patients with Parkinson's disease in parallel with improvement in motor performance.

High-frequency stimulation (HFS) of the subthalamic nucleus (STN) is a well-established therapy for patients with severe Parkinson's disease (PD), but its mechanism of action is unclear. Exaggerated oscillatory synchronization in the beta (13-30 Hz) frequency band has been associated with bradykinesia in patients with PD. Accordingly, we tested the hypothesis that the clinical benefit exerted by STN HFS is accompanied by suppression of local beta activity.

Stereotactic localization of the human pedunculopontine nucleus: atlas-based coordinates and validation of a magnetic resonance imaging protocol for direct localization.

The pedunculopontine nucleus (PPN) is a promising new target for deep brain stimulation (DBS) in parkinsonian patients with gait disturbance and postural instability refractory to other treatment modalities. This region of the brain is unfamiliar territory to most functional neurosurgeons. This paper reviews the anatomy of the human PPN and describes novel, clinically relevant methods for the atlas-based and MRI-based localization of the nucleus.

Pallidal deep brain stimulation in the treatment of Meige syndrome.

Background: Pallidal deep brain stimulation (DBS) of globus pallidus internus (Gpi) has emerged as an effective treatment for dystonia. The experience is however limited concerning focal dystonias and to date only a few cases of pallidal DBS in the treatment of Meige syndrome have been published.

Methods/results: We here present a patient with Meige syndrome in whom unilateral pallidal DBS failed to improve the axial symptoms, but bilateral stimulation resulted in a major improvement.

Multicenter study on deep brain stimulation in Parkinson's disease: an independent assessment of reported adverse events at 4 years.

Ongoing adverse events (AEs) at 4-years postsurgery in 69 patients with advanced Parkinson's disease (PD) who received deep brain stimulation (DBS) of the subthalamic nucleus (STN) (n = 49) or the internal globus pallidus (GPi) (n = 20), in the framework of a subset of eight centers of a multicenter study, were analyzed by an independent ad hoc committee. At baseline, the patients' age, sex, disease duration, and clinical condition were virtually identical, as was the duration of follow-up. There were 64 AEs reported in 53% of STN DBS patients and eight AEs reported in 35% of GPi DBS patients.

Cortical evoked potentials from pallidal stimulation in patients with primary generalized dystonia.

Deep brain stimulation (DBS) of globus pallidus internus (GPi) has emerged as an effective treatment for primary generalized dystonia. However, the physiological mechanisms of improvement are not fully understood. Cortical activity in response to pallidal stimulation was recorded in 6 patients with primary generalized dystonia >6 months after bilateral GPi DBS.

Effects of low-frequency stimulation of the subthalamic nucleus on movement in Parkinson's disease.

Excessive synchronization of basal ganglia neural activity at low frequencies is considered a hallmark of Parkinson's disease (PD). However, few studies have unambiguously linked this activity to movement impairment through direct stimulation of basal ganglia targets at low frequency. Furthermore, these studies have varied in their methodology and findings, so it remains unclear whether stimulation at any or all frequencies < or = 20 Hz impairs movement and if so, whether effects are identical across this broad frequency band.

The peripeduncular nucleus: a novel target for deep brain stimulation?

The pedunculopontine nucleus, a promising new target for deep brain stimulation in Parkinson's disease, straddles the pontomesencephalic junction--unfamiliar territory to most functional neurosurgeons. This contribution reviews the anatomy of the pedunculopontine and peripeduncular nuclei. Given the reported findings of Mazzone et al.

Thalamic deep brain stimulation in the treatment of essential tremor: a long-term follow-up.

Deep brain stimulation (DBS) of the nucleus ventralis intermedius thalami (Vim) in the treatment of essential tremor (ET) is well documented concerning the acute effects. Reports of the long-term effects are, however, few and the aim of the present study was to analyse the long-term efficacy of this treatment. Nineteen patients operated with unilateral Vim-DBS were evaluated with the Essential Tremor Rating Scale (ETRS) before surgery, and after a mean time of 1 and 7 years after surgery.