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At least 811 records · Page 45Linked to original sources
PubMed1999

Use of spiral computerized tomography in lieu of angiography for preoperative assessment of living renal donors.

PURPOSE: We evaluate whether spiral computerized tomography (CT) can be used in lieu of renal angiography for preoperative assessment of living renal donors, with special attention to multiplicity of renal vasculature. MATERIALS AND METHODS: A total of 47 living renal donor candidates were evaluated with spiral CT and all but 2 underwent donor nephrectomy. Patients were divided into early and late groups because there was a learning curve with spiral CT. In the early group 18 donors underwent renal angiography as well as spiral CT and 10 underwent nephrectomy after spiral CT only. In the late group 5 had dual radiographic evaluation for ambiguities in spiral CT interpretation and 12 underwent nephrectomy after spiral CT only. Spiral CT was performed and interpreted blind to angiographic results, and vice versa. RESULTS: Spiral CT identified 50 of 52 renal arteries (96%) found at surgery overall and 23 of 25 (92%) found at surgery after spiral CT only. Two accessory arteries were missed in the 10 early group donors evaluated with spiral CT only, yielding an early negative predictive value of 80%. Renal angiography identified another accessory artery missed by spiral CT in the early group. All 3 missed vessels were identified retrospectively. No arteries found at surgery were missed in the late group (negative predictive value 100%), although there were 2 false-positive results detected by spiral CT relative to renal angiography in 1 candidate renal unit. Overall accuracy to predict early renal artery division relative to surgical findings was 93% for spiral CT and 91% for renal angiography. However, early renal artery division was clinically significant for only 1 of 11 vessels found at surgery. Spiral CT demonstrated 4 anomalous venous returns and renal angiography identified none. However, spiral CT missed 2 accessory veins and identified only 1 of 2 fibromuscular dysplasia cases. Total cost for spiral CT and renal angiography was $886 and $2,905, respectively. CONCLUSIONS: Spiral CT is a reasonably good alternative to renal angiography for living renal donor assessment but there is a profound learning curve for performance and interpretation. Renal angiography is still the gold standard with respect to the identification of arterial multiplicity and fibromuscular dysplasia, and it should be used adjunctively in cases with spiral CT ambiguity. Neither spiral CT nor renal angiography is ideal for the assessment of early renal artery division which is seldom an issue. The benefits of spiral CT over renal angiography are potentially lower morbidity, improved donor convenience and reduced cost.

Humans↗
PubMed2006

Mentor-initiated approach in laparoscopic radical prostatectomy.

PURPOSE: We evaluated the efficacy and safety of a mentor-initiated program for laparoscopic radical prostatectomy by analyzing its effect on the learning curve. PATIENTS AND METHODS: The mentor performed 16 procedures (group I) and the trainee, assisted by the mentor, 12 (group II). The next 16 procedures were performed by the trainee without the mentor (group III). The patient groups were comparable in terms of age, serum prostate specific antigen concentration, Gleason score, and clinical stage. The operating time, blood loss, complications, and outcomes were evaluated. Statistical analysis was performed using ANOVA with the multiple-comparisons test with Bonferroni correction and the Kruskal-Wallis test, when appropriate. RESULTS: There was a statistical difference in the mean operating time in groups I and II (271 and 381 minutes, respectively; P < 0.001) and in groups I and III (271 and 386 minutes, respectively; P < 0.001), but the difference between groups II and III was not significant (P > 0.05). The mean estimated blood loss was similar in all groups (362, 395, and 434 mL, respectively; P = 0.86). The mean postoperative day 1 decrease in hemoglobin was similar in the three groups (0.65, 0.66, and 0.66 mg/dL, respectively; P = 1.00). No patient required open conversion. Postoperative complication rates were the same in groups I and III (6.25%). The mean catheterization time was longer in group III (6, 7, and 12 days; P < 0.001). The mean hospital stays (9, 8, and 8 days; P = 0.28) were similar. Stage pT(3)-pT(4a) disease was found in 75%, 41.6%, and 75% of the specimens in groups I to III, respectively. There was no statistical difference in positive-margin rates in the three groups (43.8%, 33.3%, and 37.5%; P = 0.85). CONCLUSIONS: A mentored program allows safe introduction of laparoscopic radical prostatectomy into surgical practice. Nevertheless, during the learning curve, longer operating and catheterization times have to be expected.

Aged↗
PubMed2003

Videomediastinoscopy for the diagnosis of the diseases of the lung and mediastinum.

BACKGROUND: The biopsy of the mediastinum by mediastinoscopy is established as the most accurate method especially in the lung cancer staging, but helps also in the diagnosis of various diseases of the lung and mediastinum. The videomediastinoscopic equipment offers more precise procedure and shorter learning curve in comparison with classical technique due to the sharing of the procedure with other (more experienced) surgeon. The aim of our work was to confirm the safety and reliability of the videomediastionoscopy in our department, where the use of the traditional technique was exceptional. METHODS: Patients with expansion in the mediastinum (or enlargement of the mediastinal lymph nodes) of the unknown aetiology accessible by videomediastinoscopy according to CT were included. Standard videomediastinoscopic technique was used. The attempt to take biopsy of the mediastinal tumor and/or the lymph nodes in stations 1, 2, 4, 7 according the UICC regional lymph node mapping was done. RESULTS: There were 126 patients operated by videomediastinoscopy between January 1998 and June 2003. There were 83 men with a mean age of 50.43 years (range 14 to 78 years) and 43 women with a mean age of 50.79 years (range 18 to 77 years). The diagnosis defined by explicit morphology was made in 95 cases (75.40%). In 25 cases (19.84%) the result of the biopsy was either normal lymphatic tissue or slight inflammatory changes. In three cases (2.38%) the pathologist expressed strong suspicion of the malignant disease, without clear morphology. In two cases (1.59%) all tissue samples were completely necrotic. No biopsy was done once (0.77%). There were four major groups of patients with positive histology: Patients with sarcoidosis, patients with metastases of the epithelial malignity to the mediastinal lymph nodes, patients with lymphoma and the group containing patients with a diagnosis of a low frequency (tuberculosis, sarcoma, Castleman's disease and others). No mortality was related to the procedure. We had one serious surgical complication: bleeding from the right innominate artery successfully treated by suture. CONCLUSION: Videomediastinoscopy is a safe and accurate method with a short learning curve. The key point of the diagnostic success is a proper indication for the procedure. Videomediastinoscopic equipment and its use is to be recommend to each department of general thoracic surgery.

Adolescent↗
PubMed1999

Anatomic fundoplication failure after laparoscopic antireflux surgery.

OBJECTIVE: Anatomic fundoplication failure occurs after antireflux surgery and may be more common in the learning curve of laparoscopic antireflux surgery (LARS). The authors' aims were to assess the incidence, presentation, precipitating factors, and management of anatomic fundoplication failures after LARS. SUMMARY BACKGROUND DATA: The advent of LARS has increased the frequency with which antireflux surgery is performed for the treatment of gastroesophageal reflux disease. Postoperative symptoms frequently occur and may result from physiologic abnormalities or anatomic failure of the fundoplication (e.g., displacement or disruption). Few data exist on the potential causes or best treatment of anatomic fundoplication failures. METHOD: LARS was performed in 290 patients by one of the authors over a 6-year period. In the first 53 patients (group 1), the short gastric vessels were divided on a selective basis and the diaphragmatic crura were closed only when large hiatal hernias were present. In the subsequent 237 patients (group 2), the crura were always approximated posterior to the short gastric vessels and full fundic mobilization was performed. Clinical postoperative evaluation was performed on a regular basis, with detailed tests of anatomy and physiology when untoward symptoms developed. Postoperative foregut symptoms were reported by 26% of the patients, of whom 73% were found to have an intact fundoplication. In 7% of the entire group, anatomic failure of the fundoplication was demonstrated, with the majority exhibiting intrathoracic migration of the wrap with or without disruption of the fundoplication. New-onset postoperative epigastric or substernal chest pain frequently heralded fundoplication failure. Factors correlated with the development of anatomic fundoplication failure included presence in group 1, early postoperative vomiting, other diaphragm "stressors," and large hiatal hernias. Repeat operation has been performed in 8 of the 20 patients (40%), with 5 patients successfully treated using laparoscopic techniques. CONCLUSIONS: Anatomic fundoplication failure occurred in 7% of patients undergoing LARS, with the majority occurring in patients who underwent surgery during the learning curve. Anatomic failure is associated with technical shortcomings, large hiatal hernias, and early postoperative vomiting. Full esophageal mobilization and meticulous closure of the diaphragmatic crura posterior to the esophagus should minimize anatomic functional failure after LARS.

Female↗
PubMed2001

Experience as a factor influencing the indications for laparoscopic colorectal surgery and the results.

BACKGROUND: The influence of experience on the results of treatment with laparoscopic surgery is indisputable. The establishment of indications and contraindications is relative, and varies depending on the experience of the surgeon. Learning curves have been described for a number of laparoscopic interventions, in particular laparoscopic cholecystectomy. The current prospective multicenter study investigates, among other things, the interrelation between experience and the results of treatment using laparoscopic colorectal surgery. The study makes no pronouncements on the long-term results achieved in patients with colorectal carcinoma who underwent an operation with curative intent, although relevant data were indeed collected. RESULTS: Between August 1, 1995 and February 1, 1999, a total of 1,658 patients were recruited to the prospective multicenter study initiated by the Laparoscopic Colorectal Surgery Study Group. To investigate the influence of surgical experience, two groups were formed. Group A comprised all the institutions and surgeons with experience of more than 100 laparoscopic colorectal operations. Group B contained institutions and surgeons with experience of fewer than 100 such interventions. The results of this study clearly show that in Group A, significantly more procedures involving the rectum were performed (26.7% vs 9.5%), and significantly more carcinomas were surgically managed (37.3% vs 17.3%). Despite this significantly higher level of technically difficult procedures in the patient population of group A, which was comparable in terms of age, gender, height, and weight with the patient in group B, the postoperative mortality and morbidity was, with the exception of urinary tract infections, identical between the two groups. Conversion to open surgery was significantly less frequent in group A (4.3% vs 6.9%), and, finally, the duration of the procedures performed by the more experienced surgeons of group A was appreciably shorter than in institutions with a smaller frequency of such operations. CONCLUSIONS: Laparoscopic colorectal surgery is very demanding, and can be performed with low morbidity and mortality rates only by a surgeon with above-average experience with this type of surgery and a large caseload of laparoscopic colorectal procedures. The learning curve for such procedures is appreciably longer than for other laparoscopic operations. With increasing experience, technically more demanding operations, including radical oncologic rectal laparoscopic procedures, can be performed with appreciably reduced operating times and conversion rates, but with no increase in morbidity or mortality.

Adult↗
PubMed2004

Interpretation of three-dimensional structure from two-dimensional endovascular images: implications for educators in vascular surgery.

PURPOSE: Endovascular therapy has had a major effect on vascular surgery; surgeons perform tasks in three dimensions (3D) while viewing two-dimensional (2D) displays. This fundamental change in how surgeons perform operations has educational implications related to learning curves and patient safety. We studied the effects of experience, training, and visual-spatial ability on 3D perception of 2D angiographic images of abdominal aortic aneurysms (AAA). METHODS: A novel computer-based method was developed to produce 3D depth maps based on subjects' interpretations of 2D images. Seven experts (certified vascular surgeons) and 20 novices (medical or surgical trainees) were presented with a 2D AAA angiographic image. With software specifically designed for this study, a depth map representing each subject's 3D interpretation of the 2D angiogram was produced. The novices were then randomized into a control group and a treatment group, who received a 5-minute AAA anatomy educational session. All subjects repeated the exercise on a second AAA image. Finally, all novices were given tests of visual-spatial ability, including the Surface Development Test and the Mental Rotations Test. Comparisons between experts and novices were made with depth map comparison, a subject's perception of overall object contour. RESULTS: The depth maps were significantly different (depth map comparison, P <.001) between the expert and both novice groups for the first image. After the educational intervention, the control group and the treatment group exhibited significantly different depth maps (depth map comparison, P <.001), with treatment group depth maps more similar to those of the expert group. There were no significant correlations between the visual-spatial tests and the novice depth map comparison with the expert group. CONCLUSIONS: This is the first study to examine perception of endovascular images in an educational context. Perception of overall surface contour of 3D structures from 2D angiographic images is affected by experience and training. With application of methods of vision science to an important problem in surgery, this research represents a first step in understanding the nature of visual perceptual processes involved in execution of an increasingly common clinical task. These results have implications for understanding and studying the endovascular learning curve. CLINICAL RELEVANCE: This research represents a unique collaboration in an effort to understand and solve one of the greatest problems facing surgical educators and surgeons. This research uses applied tools in vision science to understand the perceptual constraints involved in minimally invasive surgery. Specifically, we examined the mental three-dimensional maps experts use when viewing two-dimensional displays. Furthermore, we compared experts with novices in an effort to assist surgical trainees.

Aortic Aneurysm, Abdominal↗
PubMed2004

Laparoscopic radical prostatectomy: Washington University initial experience and prospective evaluation of quality of life.

BACKGROUND AND PURPOSE: The laparoscopic approach to radical prostatectomy offers an alternative to the open surgical procedure with less morbidity. We prospectively collected data including a validated quality-of-life questionnaires on our first 38 laparoscopic radical prostatectomies (LRPs). The first 10 patients (group 1), second 10 patients (group II), and the most recent 18 patients (group III) were examined separately to study the learning curve for this procedure. In addition, we determined the pattern of recovery of urinary continence, potency, and quality of life. PATIENTS AND METHODS: Between July 1999 and July 2002, 38 consecutive transperitoneal laparoscopic radical prostatectomies were performed for clinically localized prostate carcinoma. Patients completed quality-of-life questionnaires (Rand 36 Health Survey) before surgery as well as at 1, 3, 6, and 12 months and every 6 months thereafter. The patients were also interviewed by an individual not directly involved in patient care. RESULTS: One patient (the second in our experience) was converted to the open approach because of failure to progress. The average operating time for the whole series was 423 +/- 137.6 minutes (range 215-825 minutes), the last 10 procedures taking 305 +/- 63 minutes (range 215-420 minutes). Complications consisted of one case each of intraoperative bladder injury, transient superficial peroneal nerve palsy, pulmonary embolism, and bladder neck obstruction. The bladder injury was closed laparoscopically without further complication. Bladder neck obstruction was secondary to a bladder wall fold that was treated with transurethral resection 14 months after surgery with good results. Four patients in group 1 had minor anastomotic leaks, while only one patient after that had a leak (group III). Four patients required transfusion, two intraoperatively and two postoperatively. In group III, the urethral catheter remained in place for an average of 8 days (range 6-10 days). With a mean follow-up of 22.8 months (range 9-43 months), 84.8% of the patients had perfect urinary control. Postoperatively, 9 patients (27%) were fully continent on removal of the Foley catheter. At 1, 3, 6, and 9 months postoperatively, diurnal urinary control was reported by 30.3%, 48%, 72.7%, and 84.8% of the patients, respectively. One patient needed an artificial urinary sphincter. Among the incontinent patients, 24.2% had urinary urgency, and one third of these patients reported urge incontinence. CONCLUSIONS: Laparoscopic prostatectomy is a reproducible technique with a steep learning curve. Operating times and the incidence of anastomotic leaks and urinary incontinence decrease significantly after the initial 10 patients.

Erectile Dysfunction↗
PubMed2002

Financial analysis of open versus laparoscopic radical nephrectomy and nephroureterectomy.

PURPOSE: Laparoscopic radical nephrectomy and nephroureterectomy are rapidly becoming established procedures in select patients with renal cell carcinoma and upper tract transitional cell carcinoma, respectively. We present a retrospective comparative analysis of laparoscopic versus open radical nephrectomy and nephroureterectomy from a financial standpoint. The effect of the learning curve on costs incurred was also evaluated. MATERIALS AND METHODS: Detailed itemized cost data on 18 contemporary cases of open radical nephrectomy performed from September 1997 to July 1998 were compared with similar data on 20 initial laparoscopic cases performed from September 1997 to July 1998 and 15 more recent laparoscopic radical nephrectomy cases performed from August 1998 to July 1999. Financial data were also compared on 14 contemporary patients each who underwent open radical nephroureterectomy from June 1997 to December 1999, initial laparoscopic radical nephroureterectomy from June 1997 to December 1998 and more recent laparoscopic radical nephroureterectomy from January 1999 to October 2000. Yearly financial costs were adjusted for inflation by a 4% annual rate to reflect year 2000 data. RESULTS: For radical nephrectomy mean operative time in the 18 open, 20 initial laparoscopic and 15 recent laparoscopic cases was 185.3, 205.7 and 147.3 minutes, respectively. Mean specimen weight was 555, 616 and 558 gm., and mean hospital stay was 132, 31 and 23 hours, respectively. Compared with open radical nephrectomy mean total costs associated with initial laparoscopy were 33% greater (p = 0.0003). Mean intraoperative costs were 102% greater and mean postoperative costs were 50% less. In contrast, the more recent laparoscopic cases were an overall mean of 12% less expensive than open surgery (p = 0.05). Mean intraoperative costs were only 33% greater and mean postoperative costs were 68% less. For radical nephroureterectomy mean operative time in the 14 open, 14 initial laparoscopic and 14 recent laparoscopic cases was 246, 196 and 195 minutes, respectively. Mean specimen weight was 442, 517 and 531 gm., and mean hospital stay was 142, 63 and 32 hours, respectively. Compared with open radical nephroureterectomy mean total costs associated with initial laparoscopic cases were 28% greater (p = 0.03). Mean intraoperative costs were 65% greater and mean postoperative costs were 27% less. In contrast, the more recent laparoscopic cases were an overall mean of 6% less expensive than open surgery (p = 0.63). Mean intraoperative costs were only 31% greater and mean postoperative costs were 62% less. CONCLUSIONS: Initially in the learning curve laparoscopic radical nephrectomy and nephroureterectomy were 33% and 28% financially more expensive, respectively, than their open counterparts. However, with increased operator experience and efficiency resulting in more rapid operative time and decreased hospitalization laparoscopic radical nephrectomy and nephroureterectomy are currently 12% and 6% less expensive, respectively, than their open counterparts at our institution.

Aged↗
PubMed2003

Results of a standardized technique and postoperative care plan for laparoscopic sigmoid colectomy: a 30-month experience.

INTRODUCTION: Laparoscopic sigmoid colectomy has been accepted slowly despite potential advantages because of the perceptions of a steep learning curve and increased operative times and costs. The purpose of this article is to review the outcome of a standardization of all the intraoperative and postoperative processes used in our department for the performance of laparoscopic sigmoid colectomy. METHODS: A consecutive series of patients requiring laparoscopic sigmoid colectomy from March 1999 through December 2001 at the Cleveland Clinic Foundation, Cleveland, Ohio, was analyzed. Patients requiring sigmoid or rectosigmoid resection for all colonic pathologies were included. Criteria for exclusion from an attempted laparoscopic sigmoid colectomy were body mass index >35 and prior major abdominal surgeries (exclusive of hysterectomy, cholecystectomy, or appendectomy). Data collected included age, gender, indication for surgery, American Society of Anesthesiology class, body mass index, operative duration, length of hospital stay, complications, mortality, and 30-day readmission. The operative steps for laparoscopic sigmoid colectomy were as follows: 1) open insertion of the umbilical port; 2) placement of three operating ports; 3) dissection/division of the vascular pedicle after identification of the left ureter; 4) mobilization of the sigmoid and descending colon; 5) rectal mobilization/division; 6) exteriorization of the specimen; and 7) circular stapled anastomosis. Instrumentation for the procedure was standardized. Conversion was performed when a sequential step could not be completed in a reasonable time frame. A standard perioperative care plan was used. RESULTS: From March 1999 through December 2001, the primary surgeon performed 207 sigmoid colectomies, including 181 (87.4 percent) attempted laparoscopic sigmoid colectomies and 22 (12.1 percent) conversions. Indications for the laparoscopic sigmoid colectomies were diverticular disease (115), colonic neoplasia (32), prolapse (14), endometriosis (10), and other (10). The male/female ratio was 85:96, and the mean body mass index was 27.3 +/- 5.6. Mean operative time was 119 +/- 35 minutes. Mean length of stay was 2.9 +/- 1.2 days for completed cases and 6.4 +/- 1.4 days for converted cases. Anastomotic leaks occurred in two patients (1.1 percent), one of whom died of multisystem organ failure, yielding an operative mortality of 0.6 percent. The overall complication rate was 6.6 percent, and the 30-day readmission rate was 8 percent. CONCLUSION: The results indicate that a structured approach to laparoscopic sigmoid colectomy provides the surgeon with objective measures of operative progress that limit unduly long operations without increasing conversion rates and that control resource utilization. This approach provides a potential guideline for teaching and mastering laparoscopic sigmoid colectomy, reducing the learning curve, and optimizing results.

Body Mass Index↗
PubMed2004

Anterior vertebral body screw position placed thoracoscopically: a function of anatomy and surgeon experience in a porcine model.

STUDY DESIGN: Manual digital measurements, in a porcine model of thoracoscopic anterior instrumentation, divided into two studies: 1) comparing the actual screw position within each vertebra with the perceived ideal screw position and correlation with the learning curve of the surgeon; and 2) a quantitative analysis of the vertebral bodies from T3 to T12 to determine the ideal screw insertion point and trajectory. OBJECTIVE: To investigate whether the position of thoracoscopically placed screws is related to the portion of the thoracic spine instrumented and to the experience of the surgeon and to define the ideal starting position and direction of anterior thoracic screws in a porcine model. SUMMARY OF BACKGROUND DATA: Anterior screw insertion using a thoracoscopic approach is generally considered to be technically demanding and potentially dangerous. To our knowledge, there is no study analyzing the proper position of anterior vertebral screws using thoracoscopic technique and no study analyzing the ideal starting position of anterior vertebral body screws. METHODS: In Study 1, 26 pigs were assigned to two groups (early experience, n = 16; late experience, n = 10) and underwent thoracoscopic anterior instrumentation and fusion from T5 to T10. The screw position was determined in the sagittal plane and in the frontal plane, respectively. In Study 2, 10 thoracic pig spines (T3-T12) were obtained. Each vertebra was digitally measured in the midtransverse plane. Using a point directly adjacent to the rib head as the assumed ideal screw starting point, the percent of vertebral body "obscured" by the rib head and the maximum safe anterior and posterior screw insertion angles were determined. RESULTS: In Study 1, screw positions of Group 1 were significantly more anterior from T5 to T7 compared with the ideal screw position (P < 0.05). Most screws were in the ideal position in Group 2. In both groups, the screw position within T5 was too inferior (P < 0.05). The majority of posterior cortical disruptions occurred in the distal vertebrae. Most anterior disruptions occurred in the proximal vertebrae. In Study 2, the percent of vertebral body behind the rib head significantly decreased from T3 (61.5%) to T12 (25.7%) (P < 0.0001). The maximum anterior insertion angle significantly increased from T3 (11 degrees) to T12 (24 degrees) (P < 0.0001) while the maximum posterior insertion angle significantly decreased from T3 (28 degrees) to T12 (11 degrees) (P < 0.0001). CONCLUSIONS: The position of thoracoscopically placed vertebral screws is dependent on the level of the spine instrumented and surgeon experience. Screws placed in the proximal thoracic spine tend to be too anterior and too inferior while posterior placement of screws occurs in the distal thoracic spine. When using the rib head as the starting point for anterior screw insertion, a slight anterior angle is required in the distal thoracic spine while a slight posterior insertion angle is required in the proximal thoracic spine. A learning curve does exist, however; the proximal screw positioning continues to be a challenge.

Animals↗
PubMedDate not supplied

A retrospective comparison of open and endoscopic brow-lifts.

OBJECTIVES: To measure and compare surgical brow elevation with open and endoscopic techniques; to compare patients who did and did not undergo an eyelid procedure in the same setting as the brow-lift; and to determine whether a learning curve exists for a successful endoscopic brow-lift procedure. DESIGN: A retrospective review of patients who underwent coronal, trichophytic, and endoscopic brow-lift surgery from January 1, 1993, to December 31, 1997 (performed by K.A.L.). We analyzed preoperative and postoperative photographs obtained from 10 to 56 months after surgery while masked to the surgical technique used. Measurements included a horizontal baseline drawn through the midpoint of the right and left medial canthi, and extended laterally across the face; the distance from the baseline to the superior border of the medial eyebrow on the right and left sides; and the distance from the baseline to the highest point of the brow on the right and left sides. A second, nonbiased observer analyzed a random sampling of patient photographs to determine the degree of interobserver variation. SETTING: Private facial plastic and reconstructive surgery practice. All procedures were performed in an ambulatory surgery setting. PARTICIPANTS: We identified 125 patients (average age, 54 years) with greater than 10 months of postoperative photographic documentation. We excluded 41 patients owing to several inconsistencies between their preoperative and postoperative photographs and included 84. These patients were divided into 3 groups: those undergoing coronal, trichophytic, and endoscopic procedures. Of the patients undergoing concomitant eyelid procedures, 12 underwent upper lid blepharoplasties; 15, lower lid blepharoplasties; 16, bilateral upper and lower lid blepharoplasties; 6, periorbital laser resurfacing or chemical peel; 1, canthoplasty; and 1, ptosis repair. The endoscopic brow-lift procedure was not performed in this facial plastic surgery practice until 1995. To determine whether better results were obtained in the later half of the study, when the surgeon had more experience, this group was divided between the 14 patients who underwent the procedure from January 1, 1995, to June 30, 1996, and the 20 who did from July 1, 1996, to December 31,1997. MAIN OUTCOME MEASURE: Comparison of preoperative photographs with postoperative 10- to 32-month follow-up photographs and with final 35- to 56-month follow-up photographs. RESULTS: We found no statistically significant difference in: the distance of the medial brow (P =.89) or highest elevated point of the brow (P =.93) between the coronal, trichophytic, and endoscopic groups; the distance that the medial brow (P =.15) or the highest point of the brow (P =.11) was raised for those patients undergoing concomitant eyelid procedures; and the distance that the medial brow (P =.80) or highest point of the brow (P =.79) was raised between the 2 endoscopic brow-lift groups. Interobserver variation in brow measurements was 0.1 cm or less in more than 90% of cases. CONCLUSIONS: Both open and endoscopic brow-lift techniques described herein elevate the entire brow successfully. We found no statistical difference in patients undergoing concomitant eyelid procedures, and there was no identification of a "learning curve" for a successful endoscopic brow-lift with the surgical technique described.

Endoscopy↗
PubMed2001

Algebraic geometrical methods for hierarchical learning machines.

Hierarchical learning machines such as layered perceptrons, radial basis functions, Gaussian mixtures are non-identifiable learning machines, whose Fisher information matrices are not positive definite. This fact shows that conventional statistical asymptotic theory cannot be applied to neural network learning theory, for example either the Bayesian a posteriori probability distribution does not converge to the Gaussian distribution, or the generalization error is not in proportion to the number of parameters. The purpose of this paper is to overcome this problem and to clarify the relation between the learning curve of a hierarchical learning machine and the algebraic geometrical structure of the parameter space. We establish an algorithm to calculate the Bayesian stochastic complexity based on blowing-up technology in algebraic geometry and prove that the Bayesian generalization error of a hierarchical learning machine is smaller than that of a regular statistical model, even if the true distribution is not contained in the parametric model.

Algorithms↗
PubMed1996

Colour learning in the hawkmoth Macroglossum stellatarum

Newly eclosed specimens of the day-active hawkmoth Macroglossum stellatarum were trained to artificial flowers in dual-colour choice situations. Learning curves were obtained from learning and reversed-learning experiments. Initially, learning behaviour was influenced by innate colour preferences. In comparison with other lepidopterans, Macroglossum stellatarum learns well. When trained in a dual-choice situation, the moths learned not only to visit the rewarded colour but also to avoid the unrewarded colour. These good learning abilities are discussed in the context of the biology of the species.

Journal Article↗
PubMed2006

APP23 mice display working memory impairment in the plus-shaped water maze.

Alzheimer's disease (AD) patients typically present short-term memory deficits, before long-term memory capacity declines with disease progression. Several studies have described learning and memory deficits in the APP23 mouse model. Our group reported a decline of learning and memory capacities from the age of 3 months onwards using a hidden-platform Morris water maze (MWM). The aim of the present study was to evaluate working and reference memory in APP23 mice in the same plus-shaped water maze. The transgenic mice had slower learning curves; however, consolidation of the learned information appeared intact in this learning paradigm. This report demonstrates impairment of working memory in this transgenic Alzheimer model.

Amyloid beta-Protein Precursor↗
PubMed2004

Dynamics of the adaptive natural gradient descent method for soft committee machines.

Adaptive natural gradient descent (ANGD) method realizes natural gradient descent (NGD) without needing to know the input distribution of learning data and reduces the calculation cost from a cubic order to a square order. However, no performance analysis of ANGD has been done. We have developed a statistical-mechanical theory of the simplified version of ANGD dynamics for soft committee machines in on-line learning; this method provides deterministic learning dynamics expressed through a few order parameters, even though ANGD intrinsically holds a large approximated Fisher information matrix. Numerical results obtained using this theory were consistent with those of a simulation, with respect not only to the learning curve but also to the learning failure. Utilizing this method, we numerically evaluated ANGD efficiency and found that ANGD generally performs as well as NGD. We also revealed the key condition affecting the learning plateau in ANGD.

Journal Article↗
PubMed2026

Structured robotic colorectal training in a non-tertiary NHS hospital: a 502-case consecutive cohort implementation study.

Robotic-assisted colorectal surgery has expanded rapidly across NHS practice in the UK. Structured unit-wide training pathways are essential for safe technology adoption, yet published outcome data from non-tertiary hospitals remain limited. This study describes the implementation and feasibility of a unit-wide robotic colorectal program at a high-volume non-tertiary hospital, reporting outcomes across 502 consecutive resections performed by eight consultant surgeons and presenting these in the context of nationally published benchmarks. A retrospective cohort study of 502 consecutive robotic colorectal resections performed at York Teaching Hospital between May 2022 and December 2025. Eight consultant surgeons (A-H) participated in a structured four-phase training pathway incorporating simulation training, proctored cases, complexity-based case progression, and formal credentialing. Primary outcomes were 30-day mortality, unplanned return to theatre (RTT), and anastomotic leak (AL). Anastomotic leak was calculated using only patients who underwent anastomosis as the denominator. Procedure-stratified and individual surgeon outcomes with 95% confidence intervals were reported. Risk-adjusted cumulative sum (RA-CUSUM) analysis was performed to evaluate learning curves. Outcomes are presented descriptively alongside nationally published reference data; no formal statistical comparison against national benchmarks was performed. 502 robotic colorectal resections were performed. Mean patient age was 70.0 &#xb1; 11.3&#xa0;years; 58.4% were male. Median ASA grade was III. The indication was malignancy in 89.2% of cases. Length of stay was non-normally distributed and is therefore reported using median and interquartile range in the revised analysis. Key outcomes: - 30-day mortality: 1.0% (5/502; 95% CI 0.4-2.3%) - Unplanned return to theatre (RTT): 5.2% (26/502; 95% CI 3.6-7.5%) - Anastomotic leak (AL): 3.3% (15/450; 95% CI 2.0-5.5%; denominator = patients with anastomosis) - 30-day unplanned readmission: 5.0% (25/502; 95% CI 3.4-7.2%) - Conversion to open surgery: 3.6% (18/502; 95% CI 2.3-5.6%) - Lymph node yield &#x2265;12: 91.3% of cancer resections - R0 resection rate: 95.1% of cancer resections All primary outcomes fell within or below the published reference ranges used for descriptive context. RA-CUSUM trajectories were heterogeneous: no surgeon crossed the predefined upper control limit, but several curves showed later upward movement. Accordingly, the analysis is interpreted as safety surveillance rather than evidence of uniform performance improvement. RA-CUSUM monitoring showed that no surgeon crossed the predefined upper control limit; however, heterogeneous trajectories precluded a claim of uniform performance improvement.

Humans↗