Neuromodulation : journal of the International Neuromodulation Society
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Pre-operative psychological assessment is commonly used to assess patients for spinal cord stimulation (SCS). Though often times mandated by insurance, its value is frequently questioned. ⋯ The predictive value of psychological testing depends on which psychiatric factors are used and which outcomes are measured. The predictive capacity of psychological indications can be used to holistically treat patients, specifically to recommend psychiatric medication and consulting to supplement SCS treatment as needed.
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Spinal Cord Stimulator (SCS) is a surgically implanted device for patients with certain types of chronic pain. While some studies show the value of psychological screening of potential SCS candidates, no consensus exists. This single-site study analyzed the association of SCS success with psychological assessments (e.g., Millon Behavioral Medicine Diagnostic), beliefs regarding SCS efficacy, self-reported pain and quality of life (QOL) among patients approved for SCS. ⋯ Predictors of pain relief and QOL following SCS may depend on expectations of the device and on individuals' interpretation of pain or psychosocial health.
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Electrical stimulation of the hippocampus offers the possibility to treat patients with mesial temporal lobe epilepsy (MTLE) who are not surgical candidates. We report long-term follow-up results in five patients receiving low or high frequency hippocampal stimulation for drug-resistant MTLE. ⋯ Electrical stimulation of the hippocampus is a minimally invasive and reversible method that can improve seizure outcomes in patients with drug-resistant MTLE. The optimal frequency of stimulation varied from patient to patient and therefore required individual setting. These experimental results warrant further controlled studies with a large patient population to evaluate the long-term effect of hippocampal stimulation with different stimulation parameters.
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Spinal cord stimulation (SCS) treats neuropathic pain through retrograde stimulation of dorsal column axons and their inhibitory effects on wide dynamic range (WDR) neurons. Typical SCS uses frequencies from 50-100 Hz. Newer stimulation paradigms use high-frequency stimulation (HFS) up to 10 kHz and produce pain relief but without paresthesia. Our hypothesis is that HFS preferentially blocks larger diameter axons (12-15 µm) based on dynamics of ion channel gates and the electric potential gradient seen along the axon, resulting in inhibition of WDR cells without paresthesia. ⋯ At clinical HFS frequencies and pulse widths, HFS preferentially blocks larger-diameter fibers and concomitantly recruits medium and smaller fibers. These effects are a result of interaction between ion gate dynamics and the "activating function" (AF) deriving from current distribution over the axon. The larger fibers that cause paresthesia in low-frequency simulation are blocked, while medium and smaller fibers are recruited, leading to paresthesia-free neuropathic pain relief by inhibiting WDR cells.