Bilateral STN stimulation safely improves all parkinsonian symptoms, decreases or eliminates the need for levodopa, and ameliorates motor fluctuations and dyskinesias. Complete withdrawal of levodopa is feasible with this technique and the overall motor effect of STN stimulation is quantitatively comparable to that obtained with levodopa.

We examined the impact of the subthalamic nuclei (STN) deep brain stimulation (DBS) on the health-related quality of life (QoL) of patients with advanced Parkinson's disease (PD). Seventeen consecutive patients with refractory motor fluctuations and dyskinesia were included in the study (mean age, 60.9 +/- 7.7 years [range, 43-74 years]; disease duration, 16.4 +/- 8.5 years [range, 7-38 years]; mean off-medication Hoehn and Yahr stage, 4.23 +/- 0.66 [range, 2.5-5]). Each patient's assessment was carried out using common rating scales, following the Core Assessment Program for Intracerebral Transplantation (CAPIT) protocol. Dyskinesia and emotional state were evaluated through the Abnormal Involuntary Movement Scale (AIMS) and the Hospital Anxiety and Depression Scale (HAD). QoL was assessed by means of the Parkinson's Disease Questionnaire Spanish version (PDQ-39). Significant benefit was obtained in the motor manifestations and complications of disease, as well as in the functional state and mood (P < 0.001). Some QoL dimensions (mobility and activities of daily living) and the PDQ-39 Summary Index (PDQ-39SI) showed a significant improvement (P < 0.001). Benefit was modest (P < 0.05) for three other domains (emotional well-being, stigma, bodily discomfort) and nil for the rest. There was no correlation between the change obtained in the QoL (PDQ-39SI) and in the other variables. As measured by the PDQ-39, STN-DBS significantly improves important aspects of QoL in patients with advanced PD.

Cell swelling activates a regulatory volume decrease mechanism that implies activation of K(+) and Cl(-) currents and participation of P2Y(2) receptors. Because previous studies have shown that intracellular volume of TM cells is an important determinant of outflow facility, it seems feasible that cell volume regulation would be part of the homeostatic mechanisms of the TM, to regulate the outflow pathway.

Adaptive, long-term alterations of excitability have been reported in dendrites and presynaptic terminals but not along axons. Persistent enhancement of axonal excitability has been described in proximal nerve stumps at sites of nerve section in mammals, but this hyperexcitability is considered a pathological derangement important only as a cause of neuropathic pain. Identified neurons in Aplysia were used to test the hypothesis that either axonal injury or the focal depolarization that accompanies axonal injury can trigger a local decrease in action potential threshold [long-term hyperexcitability (LTH)] having memory-like properties. Nociceptive tail sensory neurons and a giant secretomotor neuron, R2, exhibited localized axonal LTH lasting 24 hr after a crush of the nerve or connective that severed the tested axons. Axons of tail sensory neurons and tail motor neurons, but not R2, displayed similar localized LTH after peripheral depolarization produced by 2 min exposure to elevated extracellular [K ϩ ]. Neither the induction nor expression of either form of LTH was blocked by saline containing 1% normal [Ca 2ϩ ] during treatment or testing. However, both were prevented by local application of the protein synthesis inhibitors anisomycin or rapamycin. The features of (1) long-lasting alteration by localized depolarization, (2) restriction of alterations to intensely depolarized regions, and (3) dependence of the alterations on local, rapamycin-sensitive protein synthesis are shared with synaptic mechanisms considered important for memory formation. This commonality suggests that relatively simple, accessible axons may offer an opportunity to define fundamental plasticity mechanisms that were important in the evolution of memory.

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