Comparison Between Cz-C3/C4 and C3-C4 Montages to Protect Against Peripheral Stimulation in Transcranial Facial Motor-Evoked Potential Monitoring.

INTRODUCTION: In facial motor-evoked potential monitoring, efforts to reduce peripheral stimulation are necessary because it can cause false-negatives. The effects of peripheral stimulation on Cz-C3/C4 and C3-C4 montages were compared. METHODS: Facial motor-evoked potentials were recorded from bilateral orbicularis oculi (Oculi) and oris (Oris) muscles. The double-train approach combining single-pulse and five-train pulse stimulation was used to determine the effect of peripheral stimulation. If the five-train pulse produced a significant waveform, it was defined as "total success." In total success cases, "true success" was defined as a case in which no waveform appeared after the single pulse at the threshold level of the five-train pulse. The total and true success rates and the threshold value of Oculi and Oris were compared between Cz-C3/C4 and C3-C4 montages. RESULTS: Thirty-six muscles each of Oculi and Oris of 18 patients were used for the analysis. True success was more likely to be obtained by the Cz-C3/C4 montage than the C3-C4 montage in Oculi (42% vs. 22%, p = 0.039). Both Oculi and Oris had higher thresholds to elicit facial motor-evoked potentials with the Cz-C3/C4 montage (Oculi: 101.7 vs. 71.4 mA, p = 0.038; Oris: 94.8 vs. 73.1 mA, p = 0.016). CONCLUSIONS: Cz-C3/4 montage is more effective at reducing peripheral stimulation compared with the C3-4 montage. This effect was primarily seen in the orbicularis oculi muscle. It should be noted that the Cz-C3/C4 montage has a higher threshold than the C3-C4 montage in facial muscles. In facial motor-evoked potential monitoring, the Cz-C3/C4 montage may be more suitable to eliminate peripheral stimulation.

Automatic encoding of a target position relative to a natural scene.

We previously showed that the brain automatically represents a target position for reaching relative to a large square in the background. In the present study, we tested whether a natural scene with many complex details serves as an effective background for representing a target. In the first experiment, we used upright and inverted pictures of a natural scene. A shift of pictures significantly attenuated prism adaptation of reaching movements as long as they were upright. In one-third of participants, adaptation was almost completely cancelled whether the pictures were upright or inverted. It was remarkable that there were two distinct groups of participants, one who relies fully on the allocentric coordinate and the other who depended only when the scene was upright. In the second experiment, we examined how long it takes for a novel upright scene to serve as a background. A shift of the novel scene had no significant effects when it was presented for 500 ms before presenting a target, but significant effects were recovered when presented for 1,500 ms. These results show that a natural scene serves as a background against which a target is automatically represented once we spend 1,500 ms in the scene.NEW & NOTEWORTHY Prism adaptation of reaching was attenuated by a shift of natural scenes as long as they were upright. In one-third of participants, adaptation was fully canceled whether the scene was upright or inverted. When an upright scene was novel, it took 1,500 ms to prepare the scene for allocentric coding. These results show that a natural scene serves as a background against which a target is automatically represented once we spend 1,500 ms in the scene.

Intractable hyperkalemia caused by hepatic infarction developed during laparoscopic gastrectomy in a patient with end-stage renal failure: a case report.

BACKGROUND: Patients with renal failure are susceptible to electrolyte disturbances including life-threatening hyperkalemia, and intraoperative hepatic damage exacerbates it. We report a case on hemodialysis who developed intraoperative remarkable hyperkalemia caused by hepatic damage during laparoscopic gastrectomy. CASE PRESENTATION: A 48-year-old man underwent laparoscopic gastrectomy for gastric cancer. He had been on hemodialysis for chronic renal failure. Serum K+ continued to increase to a maximum level of 7.4 mEq/L, despite the infusion of glucose with insulin during surgery. Postoperative computed tomography revealed hepatic infarction. Combined with increased hepatic enzymes, hepatic infarction caused by intraoperative mechanical traction would have exacerbated hyperkalemia. CONCLUSIONS: We report a case on hemodialysis who developed intraoperative hyperkalemia due to hepatic damage. Our case highlights hepatic damage during laparoscopic gastrectomy as a potential cause of hyperkalemia.

Transversus abdominis plane block for bilateral orchiopexy in an 8-year-old patient with Eisenmenger's syndrome.

Non-cardiac surgery should only be performed in patients with Eisenmenger's syndrome if absolutely mandatory because these patients are at high risk of perioperative mortality. Proper anesthetic and perioperative pain management in these patients remains a controversial topic. Transversus abdominis plane (TAP) block provides safe and beneficial perioperative analgesia in adults and children; however, no report has described the performance of TAP block in a child with Eisenmenger's syndrome. Herein, we describe the performance of bilateral orchiopexy for cryptorchidism in an 8-year-old boy with Eisenmenger's syndrome due to an uncorrected muscular ventricular septal defect (mVSD). Anesthesia induction and maintenance were uneventful. Subsequently, the patient received ultrasound-guided bilateral TAP block by using 10 mL of 0.25 % levobupivacaine shortly before recovery from anesthesia. The TAP block provided pain relief and maintenance of stable hemodynamics during the postoperative period. We successfully used a TAP block in a child with Eisenmenger's syndrome to provide postoperative analgesia. No side effects were apparent during the perioperative period. TAP block can be considered a beneficial pain management technique for analgesia in children with Eisenmenger's syndrome.

[Perioperative management of a child with central diabetes insipidus who underwent two surgeries before and after desmopressin administration].

A 14-year-old girl weighing 32 kg was diagnosed with suprasellar tumor causing hydrocephalus, hypothyroidism, adrenal dysfunction and central diabetes insipidus. She was treated with levothyroxine and hydrocortisone and urged to take fluid to replace urine. She was scheduled to undergo ventricular drainage to relieve hydrocephalus prior to tumor resection. For the first surgery, desmopressin was not started and urine output reached 4,000 to 6,000 ml x day(-1), urine osmolality 64 mOsm x l(-1) and urine specific gravity 1.002. Anesthesia was induced with sevoflurane and maintained with propofol and remifentanil. Maintenance fluid was with acetated Ringer's solution and urine loss was replaced with 5% dextrose. Bradycardia and hypotension occurred after intubation, which was treated with volume load. Infusion volume was 750 ml and urine output was 1100 ml during 133 min of anesthesia. Postoperative day 1 nasal desmopressin was started. Ten days later, partial tumor resection was performed. Anesthesia was induced with propofol and fentanyl and maintained with sevoflurane and remifentanil. Infusion volume was 610 ml, urine output 380 ml, and blood loss 151 ml during 344 min of anesthesia. Hemodynamic parameters were stable throughout the procedure. Pathology of the tumor was revealed to be germinoma. Bradycardia and hypotension experienced during the first surgery was suspected to be caused by preoperative hypovolemia brought by polyuria. Desmopressin was proved to be effective to treat excessive urine output and to maintain good perioperative water balance.

[Epidural blood patch for postdural puncture headache in a five-year-old child].

A case was presented of a 5-year-old girl who suffered an accidental dural puncture during placement of an epidural catheter under general anesthesia for orthopedic surgery. She complained of headache 4 days after the operation, which was relieved on supine position but became worse on sitting position. Her symptoms failed to respond to conservative management. An epidural blood patch was performed under general anesthesia and completely resolved her symptoms. The reported incidence of epidural blood patch for post dural puncture headache following accidental dural puncture in children is low. We outline this case and the consideration for management for epidural blood patch in pediatric patients.