Neuromodulation : journal of the International Neuromodulation Society
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Neuropathic pain affects various dimensions of patient health including physical, psychological, and socioeconomic. The spectrum of psychological dysfunction that accompanies this pain phenotype is unknown, as well as differences based on the etiology of the pain among patients referred for spinal cord stimulation (SCS). ⋯ The high frequency of depressive and anxiety symptoms screened by the Beck scores in this cohort is an order of magnitude higher than seen in the general population. That many of these cases are undiagnosed should motivate clinicians from primary care providers, comprehensive pain specialists, and surgeons to screen SCS patients for such psychopathology. This represents an opportunity to enhance overall pain management as well as success with invasive neuromodulation strategies.
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Prelemniscal radiations (Raprl) have been proposed as a target for the treatment of Parkinson's disease. We evaluated effectiveness of this target through UPDRS-III in patients treated with Raprl deep brain stimulation (Raprl-DBS) and followed from 24 to 48 months. ⋯ Raprl-DBS induces a long-term, significant improvement of contralateral acral symptoms of Parkinson's disease.
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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.