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Hello Friends, The continuing story of thalamic Stimulation. I typed this from a brochure from the company Medtronic called : "Thalamic Stimulation System, Therapy Reference Guide" Section 1 : OVERVIEW OF THALAMIC STIMULATION FOR TREATMENT OF TREMOR Uses and patients Benefits Stimulation of the ventral intermediate (VIM) nucleus of the thalamus (figure 1; it shows a picture of a head, with the spot where the lead is implanted) is indicated as a therapy for patients with disabling tremor who are not suitable candidates for drug therapy or whose tremor has not been adequately controlled by drug therapy Many patients treated with thalamic stimulation gain substantial control over otherwise refractory tremor. their quality of life improves as they are able to participate more fully in daily activities. Definition: tremor Tremor is defined as the rhytmic, oscillating movements of a body part due to repetitive patterns of muscle contraction and relaxation. It is classified as : * Rest tremor -- occurs during rest * Postural tremor --occurs when limbs are upright (working against gravity) * Kinetic tremor -- occurs during limb movement The origin of tremor is thought to be in the brain.Stimulation of the VIM nucleus inhibits tremor, Allthough the exact mechanism is unknown. Tremor is a prominent signof Parkinson's disease (PD) and the only sign of essential tremor (ET), both of which can be treated with thalamic stimulation. Rest tremor is pathognomonic for PD, allthough postural tremor is not uncommon. In severe cases of PD, rest and postural tremor (mixed tremor) may be manifest. Postural tremor is typical of essential tremor, allthough kinetic tremor may also be present. Tremor Therapy Tremor is effectively managed pharmacologically in the majority of patients. When tremor becomes medically intractable and severly disabling, stimulation of the VIM nucleus may provide relief. Thalamic stimulation is non destructive and reversible. It can be used to treat bilateral tremor. The tremor-suppressing effect of thaamic stimulation have known since the 1920's. Very llittle, however, is known about the mechamism of action. According to Benabid et al. (1993), thalamic stimulation does not appear to suppress tremor by an excitatory or inhibitory effect. Rather, it is more likely that tremor supprression results from jamming the neuronal network processing proprioceptive inputs to the thalamus. Stimulation Test Patients are tested for tremor suppression typically as a first step in the stimulation system implant procedure. A test electrode is stereotactically placed in the brain to locate the target site. Then an external stimulator, such as the model 3625 Screener, is used to determine whether or not stimulation suppresses the tremor. If no tremor suppression occurs, the implant procedure is discontinued. If the tremor is suppressed satisfactorily, the model 3387 lead is implanted. The physician then has the option of either implanting the IPG immediately after the lead is implanted or using the screener for a trial period before implanting the IPG. Thalamic stimulation System To perform thalamic stimulation for the treatment of tremor, Medtronic provides a system of components consisting of an implantable pulse generator (IPG), lead, extension and external programmer (table 1; An overview of the components) Therapeutic Efficacy Clinical studies show that thalamic stimulation is effective in treating tremor. Table 2 summaries the clinical results. (to be continued)