Subthalamic deep brain stimulation at individualized frequencies for Parkinson disease.

OBJECTIVES: The oscillation model of Parkinson disease (PD) states that, in the subthalamic nucleus (STN), increased θ (4-10 Hz) and ß (11-30 Hz) frequencies were associated with worsening whereas γ frequencies (31-100 Hz) were associated with improvement of motor symptoms. However, the peak STN frequency in each band varied widely from subject to subject. We hypothesized that STN deep brain stimulation (DBS) at individualized γ frequencies would improve whereas θ or ß frequencies would worsen PD motor signs. METHODS: We prospectively studied 13 patients with PD. STN local field potential (LFP) was recorded after electrode implantations, in the OFF and then in ON dopaminergic medication states while patients performed wrist movements. Six individual peak frequencies of the STN LFP power spectra were obtained: the greatest decrease in θ and ß and greatest increase in γ frequencies in the ON state (MED) and during movements (MOVE). Eight DBS frequencies were applied including 6 MED and MOVE frequencies, high frequency (HF) used for chronic stimulation, and no stimulation. The patients were assessed using the motor Unified Parkinson's Disease Rating Scale (mUPDRS). RESULTS: STN DBS at γ frequencies (MED and MOVE) and HF significantly improved mUPDRS scores compared to no stimulation and both γ frequencies were not different from HF. DBS at θ and ß frequencies did not worsen mUPDRS scores compared to no stimulation. CONCLUSION: Short-term administration of STN DBS at peak dopamine-dependent or movement-related γ frequencies were as effective as HF for reducing parkinsonian motor signs but DBS at θ and ß frequencies did not worsen PD motor signs. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that STN DBS at patient-specific γ frequencies and at usual high frequencies both improved mUPDRS scores compared to no stimulation and did not differ in effect.

[The role of oxidative stress in normal and pathological adaptive reactions]. / Rolul stresului oxidativ în reactiile adaptative normale si patologice.

After a brief presentation of the data concerning the mechanism of production of oxidative stress as an expression of cellular and molecular stressing aggression, the main actions and functional implications of the excess of free radicals at the level of the main tissues and organs are presented. Emphasis is made on the nuclear, cytosolic and membrane alterations produced by the lipid peroxidation phenomena and the cell protein degradation induced by the oxidative stress. Special attention is given to the beneficial and harmful properties of the free radical species of oxygen and nitrogen, beginning with their involvement in the production of the normal adaptive reactions and ending with their involvement in the pathogenesis of various pathological states. In the group of beneficial effects are included along with the antibacterial and antiviral properties of the free radicals and their participation in the autoregulation of the local arteriolar-capillary circulation network. As harmful properties are mentioned the cellular destructive phenomena produced by the free radicals, which are considered as the generators of a true radicals pathology (senescence, atherogenesis, cancerogenesis, neurodegenerative diseases, etc).