Less Pain Relief, More Depression, and Female Sex Correlate With Spinal Cord Stimulation Explants.

BACKGROUND: Spinal cord stimulation (SCS) is a known therapy for a variety of chronic pain conditions, but over time a number of patients proceed to explants. OBJECTIVES: We compared explant rates based on degree of pain relief, diagnosis, lead location, gender, and age to determine possible predictors for SCS implant success. METHODS: First, we performed a single-center retrospective chart review of consecutive SCS-implanted subjects was to document internal explant rates. Rates of explants based on diagnosis, gender, age, and lead location were compared to determine potential trends. We then examined which thoracic SCS patients in our prospectively collected outcome measures data base who were explanted. RESULTS: A total of 63 of 671 thoracic SCS were explanted. Thoracic explants occurred in patients who were significantly younger (p = 0.03). Women who were explanted reported significantly more discomfort from the device (p = 0.05). When we looked at our data base of patients with a mean time implanted of 2.77 years and a minimum of one year follow-up, 11 of 114 thoracic SCS patients were explanted. All explants were women. There was no correlation with diagnosis or age. Those who were explanted reported more pain (p = 0.03) and depression (p < 0.01) at one year follow-up. CONCLUSIONS: Our data correlates explants with less pain relief and more depression. Women are more likely to have explants than men. The role of physiologic and psychosocial variables leading to this difference has yet to be elucidated.

A Drosophila KCNQ channel essential for early embryonic development.

The mammalian voltage-dependent KCNQ channels are responsible for distinct types of native potassium currents and are associated with several human diseases. We cloned a novel Drosophila KCNQ channel (dKCNQ) based on its sequence homology to the mammalian genes. When expressed in Chinese hamster ovary cells, dKCNQ gives rise to a slowly activating and slowly deactivating current that activates in the subthreshold voltage range. Like the M-current produced by mammalian KCNQ channels, dKCNQ current is sensitive to the KCNQ-specific blocker linopirdine and is suppressed by activation of a muscarinic receptor. dKCNQ is also similar to the mammalian channels in that it binds calmodulin (CaM), and CaM binding is necessary to produce functional currents. In situ hybridization analysis demonstrates that dKCNQ mRNA is present in brain cortical neurons, the cardia (proventriculus), and the nurse cells and oocytes of the ovary. We generated mutant flies with deletions in the genomic sequence of dKCNQ. Embryos produced by homozygous deletion females exhibit disorganized nuclei and fail to hatch, suggesting strongly that a maternal contribution of dKCNQ protein and/or mRNA is essential for early embryonic development.