Differences in Mechanical Parameters of Keyboard Switches Modulate Motor Preparation: A Wearable EEG Study.

The mechanical parameters of keyboard switches affect the psychological sense of pressing. The effects of different mechanical parameters on psychological sense have been quantified using questionnaires, but these subjective evaluations are unable to fully clarify the modulation of information processing in the brain due to these differences. This study aimed to elucidate the ability of electroencephalography (EEG) measurements to detect the modulation of subconscious information processing according to mechanical parameter values. To this end, we prepared five mechanical switches with linearly increasing values of pretravel (PT: the distance from the free position until the operating position). We hypothesized that the differences in PTs would subconsciously affect the motor preparation prior to pressing switches because switches with PTs that deviated from those commonly used were predicted to increase the users' attention level when pressing. Differences in motor preparation were quantified using the mean amplitudes of the late contingent negative variation (CNV). We recorded EEGs of 25 gamers during a reaction task for fast switch pressing after a response cue preceded by a pre-cue for response preparation; we also measured the reaction time feedback on each switch pressing trial. Participants performed five sessions (60 trials per session) in total. For the analysis, trials were divided into first (session 1, 2, and 3) and second half sessions (session 4 and 5). In the latter session, CNV amplitudes were significantly higher for the switch with the highest PT than for that with a medium PT, which is closest to that commonly used in commercial mechanical switches. On the other hand, the questionnaire did not detect any significant differences between PTs in their subjective rankings of the psychological effects of switch pressing. These results suggest that differences in PTs modulate motor preparation to press switches, and that EEG measurements may provide a novel objective evaluation of the mechanical parameters of keyboard switches.

Middle-segment-preserving pancreatectomy for biliary-pancreatic tumors.

BACKGROUND/AIMS: Intraductal papillary mucinous neoplasm (IPMN) and pancreatic endocrine tumors can develop at multiple sites of the pancreas at the same time, sometimes necessitating total pancreatectomy. When low-grade pancreatic malignancy is treated surgically, preservation of function to improve long-term QOL is emphasized. For low grade malignancy tumor of the pancreatic head and tail, we performed middle- segment-preserving pancreatectomy (MSPP), with resection of the pancreatic head and tail alone, resulting in favorable QOL. METHODOLOGY: MSPP was performed for 4 patients. Intraoperative blood loss, hospital stay, postoperative complications, histopathological findings and prognosis were examined. RESULTS: Mean intraoperative blood loss was 1255 +/- 365g, mean hospital stay 61 +/- 53 days, and mortality 0%. Postoperatively, pancreatic fistula was observed in 3 patients, but subsided with conservative treatment. In one patient with diabetes preoperatively, diabetes was exacerbated postoperatively, necessitating insulin treatment. No postoperative onset of diabetes was observed. Percent change in body weight during the postoperative 6 month period from preoperative weight was 93 +/- 6.3%. One patient died of malignant lymphoma 1 year and 4 months after surgery. The other patients are alive and socially active. CONCLUSION: MSPP enables maintenance of good QOL long after surgery for malignancy affecting the head and tail of the pancreas.

Surgical design and outcome of duodenum-preserving pancreatic head resection for benign or low-grade malignant tumors.

To apply duodenum-preserving pancreatic head resection (DPPHR) as radical procedure for benign or low-grade malignant tumors, it needs the reconciliation of complete pancreatic head resection and preservation of the bile duct and peripancreatic vessels. Several modifications have been introduced and applied to remove these lesions, however, the techniques have not been made clear in the management of the peripancreatic vessels and the bile duct. The long-term outcomes of the DPPHR have been reported as extremely rare in comparison with pylorus preserving pancreatoduodenectomy (PPPD) in these pancreatic head tumors. The angiograms by multi-detector row CT (MD-CT) can be reconstructed more physiologically than selective angiography. The anterior arcade is predominant in 43% of 64 patients. Therefore, we modified the DPPHR to include a complete resection of the pancreatic head and the preservation of both anterior and posterior arterial arcades. The bile duct is covered by the pancreatic parenchyma in various ways. The techniques of the preservation of the bile duct are also introduced. We performed 21 DPPHRs and 19 PPPDs in the patients with benign or low-grade malignant pancreatic head tumor. There was no significant difference in operative factors. The postoperative death was one patient in PPPD, but none in DPPHR. The postoperative complications of PPPD were more often than that of DPPHR. There is no postoperative recurrence in DPPHR in the follow-up period from 2 to 216 months. Both exocrine and endocrine function and the long-term results following DPPHR were superior to those following PPPD. The DPPHR should be favored over the PPPD in benign or low-grade malignant tumors of the head of the pancreas if there is no compromise with oncologic radicality.

Pancreatoduodenectomy in which dissection of the efferent arteries of the head of the pancreas is performed first.

BACKGROUND/PURPOSE: Pancreatoduodenectomy (PD) is one of the most difficult operations in gastrointestinal surgery. Standard PD ligates and cuts superior mesenteric vein (SMV) branches after the removal of the pancreas head, which leads to congestion and bleeding of these veins. METHODS: In this study, we modified the standard PD and first ligated the efferent vessels (arteries); namely, the gastroduodenal artery and inferior pancreatoduodenal artery (IPDA), before ligating and cutting the corresponding afferent vessels (veins) of the pancreas head. By doing this, congestion of these veins was relieved and bleeding from the resected surface was substantially prevented. Thirty-six patients (18 underwent standard PD and 18 had modified PD) formed the study population. RESULTS: The amount of bleeding in the modified PD group was significantly lower than that in the standard PD group. (678 +/- 329 g vs 1225 +/- 375 g, respectively; P < 0.05) However, no difference in operation time was found between the two groups. CONCLUSIONS: We believe this modified PD procedure is valuable to enable the safe performance of PD.