Pain
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Motor cortex stimulation is generally suggested as a therapy for patients with chronic and refractory neuropathic pain. However, the mechanisms underlying its analgesic effects are still unknown. In a previous study, we demonstrated that cortical stimulation increases the nociceptive threshold of naive conscious rats with opioid participation. ⋯ Furthermore, motor cortex stimulation enhanced neuronal firing rate and Fos immunoreactivity in the ipsilateral periaqueductal gray. We have also observed a decreased Zif268, δ-aminobutyric acid (GABA), and glutamic acid decarboxylase expression within the same region, suggesting an inhibition of GABAergic interneurons of the midbrain periaqueductal gray, consequently activating neurons responsible for the descending pain inhibitory control system. Taken together, the present findings suggest that inhibition of thalamic sensory neurons and disinhibition of the neurons in periaqueductal gray are at least in part responsible for the motor cortex stimulation-induced antinociception.
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Slow-release strong opioids (SRSO) are indicated in patients with severe chronic pain. Side effects, lack of efficacy and risk of dependency limit their use in clinical practice. The aim of this study was to explore prescription patterns of SRSO in Swedish real-world data on patients with a diagnosis related to chronic pain (DRCP). ⋯ In conclusion, fewer patients remain on SRSO in the long-term in clinical practice than reported in previous clinical trials. Oxycodone is the most common first SRSO prescription and one-third of patients get a prescription indicating psychiatric comorbidity. Our interpretation of these findings are that there is need for better treatment options for these patients, and that more effort is needed to improve treatment guidelines and to ascertain that these guidelines are followed.