Embedding a Panoramic Representation of Infrared Light in the Adult Rat Somatosensory Cortex through a Sensory Neuroprosthesis.

Can the adult brain assimilate a novel, topographically organized, sensory modality into its perceptual repertoire? To test this, we implemented a microstimulation-based neuroprosthesis that rats used to discriminate among infrared (IR) light sources. This system continuously relayed information from four IR sensors that were distributed to provide a panoramic view of IR sources, into primary somatosensory cortex (S1). Rats learned to discriminate the location of IR sources in <4 d. Animals in which IR information was delivered in spatial register with whisker topography learned the task more quickly. Further, in animals that had learned to use the prosthesis, altering the topographic mapping from IR sensor to stimulating electrode had immediate deleterious effects on discrimination performance. Multielectrode recordings revealed that S1 neurons had multimodal (tactile/IR) receptive fields, with clear preferences for those stimuli most likely to be delivered during the task. Neuronal populations predicted, with high accuracy, which stimulation pattern was present in small (75 ms) time windows. Surprisingly, when identical microstimulation patterns were delivered during an unrelated task, cortical activity in S1 was strongly suppressed. Overall, these results show that the adult mammalian neocortex can readily absorb completely new information sources into its representational repertoire, and use this information in the production of adaptive behaviors.

Acute rhabdomyolysis in a patient with long-term exposure to intrathecal ziconotide: a case report.

INTRODUCTION: Ziconotide is an intrathecally administered nonopioid analgesic for the treatment of severe chronic pain. Previous reports have noted rhabdomyolysis in patients receiving ziconotide during the initial single-shot trial or due to concurrent medical problems. We present a case of an acute rhabdomyolysis following an intrathecal bolus injection of ziconotide on a patient who had long-term exposure to the drug. CASE REPORT: The patient suffered from chronic neuropathic pain with diagnosis of failed back surgery syndrome and received intrathecal ziconotide for 2 years. Moderate side effects resulting from dose escalation led to a discontinuation of the drug. The pump medication was changed to morphine, which failed to provide adequate analgesia even with dose titration. A single intrathecal bolus of ziconotide, as an adjunctive therapy, resulted in good pain control. Two months later, the patient received a second ziconotide injection. Sixteen hours after the injection, she presented to local emergency center with nausea, vomiting, diarrhea, and myalgia. She had significantly increased CK levels and was admitted for intravenous hydration and close observation. Her serum CK level peaked at 4940 IU/L. The patient was discharged on hospital day 3 with a CK level of 808 IU/L. Her symptoms resolved without renal impairment. DISCUSSION: The clinical scenario described is a case of acute rhabdomyolysis from an intrathecal bolus injection of ziconotide in a patient with prior long-term exposure to the drug. The decrease in CK levels coincided well with the average half-life of ziconotide; however, the rhabdomyolysis may have been potentiated by hypokalemia.

Risk factors for surgical site infection in advanced neuromodulation pain procedures: a retrospective study.

Aim: To assess the effects of diabetes mellitus (DM) and related variables on surgical site infection (SSI) risk in neuromodulation. Methods: This retrospective study followed patients who underwent neuromodulation procedures for at least 9 months to identify postoperative infections. Demographics, clinical characteristics and surgical outcomes were compared. Results: Of 195 cases included, 5 (2.6%) resulted in SSIs. Median HbA1c was significantly higher for the cases with SSIs (8.2 vs 5.6%; p = 0.0044). The rate of SSI was significantly higher among patients with DM (17.9 vs 0%; p = 0.0005), HbA1c≥7% (37.5 vs 0%; p = 0.0009), and perioperative glucose ≥200 mg/dl (40 vs 2.3%; p = 0.0101). Conclusion: DM, elevated HbA1c and perioperative hyperglycemia may all contribute to increased risk of SSIs with neuromodulation procedures.

Infections are feared complications of surgery. It is important to identify factors that increase the risk of infection to prevent these complications. This study looked at the effects of diabetes and high blood sugar on the risk of infection associated with pain procedures. The researchers followed patients who had these procedures and looked for any infections that occurred afterward. They found that patients with diabetes and high blood sugar levels before surgery were more likely to develop infections after these procedures. More research can help establish blood sugar targets so that physicians can better manage this risk for their patients.

Clinical and technical factors associated with knee radiofrequency ablation outcomes: a multicenter analysis.

BACKGROUND: There has been a surge in interest in radiofrequency ablation (RFA) of the genicular nerves over the past decade, with wide variability in selection, technique and outcomes. The aim of this study is to determine factors associated with treatment outcome. METHODS: We retrospectively evaluated the effect of 23 demographic, clinical and technical variables on outcomes in 265 patients who underwent genicular nerve RFA for knee pain at 2 civilian and 1 military hospital. A primary outcome was designated as a > 30% decrease in average knee pain score lasting at least 3 months without cointerventions. RESULTS: The overall rate of a positive response was 61.1% (95% CI 55.2% to 67.0%). In univariable analysis, larger electrode size (p=0.01), repeated lesions (p=0.02), having>80% pain relief during the prognostic block (p=0.02), not being on opioids (p=0.04), having no coexisting psychiatric condition (p=0.02), having a lower baseline pain score (p=0.01) and having >3 nerves targeted (p=0.02) were associated with a positive outcome. In multivariate logistic analysis, being obese (OR 3.68, 95% CI 1.66 to 8.19, p=0.001), not using opioids (OR 0.35, 95% CI 0.16 to 0.77, p=0.009), not being depressed (OR 0.29, 95% CI 0.10 to 0.82, p=0.02), use of cooled RFA (OR 3.88, 95% CI 1.63 to 9.23, p=0.002) and performing multiple lesions at each neural target (OR 15.88, 95% CI 4.24 to 59.50, p<0.001) were associated with positive outcome. CONCLUSIONS: We identified multiple clinical and technical factors associated with treatment outcome, which should be considered when selecting patients for RFA treatment and in the design of clinical trials.