Combining modules for movement

We review experiments supporting the hypothesis that the vertebrate motor system produces movements by combining a small number of units of motor output. Using a variety of approaches such as microstimulation of the spinal cord, NMDA iontophoresis, and an examination of natural behaviors in intact and deafferented animals we have provided evidence for a modular organization of the spinal cord. A module is a functional unit in the spinal cord that generates a specific motor output by imposing a specific pattern of muscle activation. Such an organization might help to simplify the production of movements by reducing the degrees of freedom that need to be specified.     

Valve structure and survival in quadragenarians having aortic valve replacement for aortic stenosis (+/-aortic regurgitation) with versus without coronary artery bypass grafting at a single US medical center (1993 to 2005)

The purpose of this study was to determine the effect of simultaneous coronary artery bypass grafting (CABG) and the influence of valve structure on both early and late survival in quadragenarians having aortic valve replacement (AVR) for aortic stenosis (AS) (with or without aortic regurgitation). We analyzed survival and valve structure in 48 adults (12 women), aged 40 to 49 years, having AVR for AS from 1993 through 2005 at Baylor University Medical Center, including 7 (15%) with and 41 (85%) without simultaneous CABG. Of the 48 quadragenarians, none died within 60 days of operation. Assessment of the relation between long-term survival and gender, aortic valve structure, preoperative severity of the AS, and concomitant CABG was not possible due to the low mortality. Four patients (9%) died >60 days after AVR: at 1.8, 6.3, 7.1, and 9.9 years, respectively. The aortic valve was congenitally unicuspid in 15 patients (31%), congenitally bicuspid in 32 (67%), and 3-cuspid in 1 (2%). In conclusion, of the 48 quadragenarians having AVR for AS, 47 (98%) had a congenitally malformed aortic valve, 60-day mortality was zero, and late mortality was low (8%).     

Laparoscopic management of complicated Meckel’s diverticulum in children: a 10-year review

Background  Meckel’s diverticulum, the most common congenital anomaly of the gastrointestinal tract, is prone to develop complications in the pediatric population. The authors report their 10-year experience with the management of complicated Meckel’s diverticulum in children using laparoscopy. Methods  A retrospective review of all complicated Meckel’s diverticulum cases involving children from 1998 to 2007 was performed. The efficacy and safety of laparoscopy used to manage complicated Meckel’s diverticulum were assessed. Results  Over a 10-year period, 20 children (17 boys and 3 girls) with a mean age of 5 years (range, 7 months to 13 years) were included in the study. Of the 20 children, 12 presented with gastrointestinal bleeding, 2 had intestinal obstruction, 3 had abdominal pain mimicking acute appendicitis, 2 had inguinal hernia, and 1 had intussusception. Diagnostic laparoscopy was performed for all the patients. Laparoscopically assisted transumbilical Meckel’s diverticulectomy was performed successfully for 18 of the children. The operative time ranged from 50 to 190 min (mean, 115 min). All the children had an uneventful recovery except one, who experienced a postoperative wound infection. Ectopic gastric mucosa was found in 14 cases. Conclusions  Diverse pediatric surgical conditions result from Meckel’s diverticulum. Laparoscopy is a safe and effective method for the management of complicated Meckel’s diverticulum.     

The acceptance and feasibility of breast cancer screening in the East

Breast cancer, traditionally a disease prevalent among women in the West, has become an increasing disease burden in the East. In Hong Kong, breast cancer is the number one incident cancer in women. In Asian countries, due to the lower incidence rate, population screening is still controversial. Most screening programs are not population-based, and are either self-financed privately or partially subsidized by the government. Since the first government-subsidized screening program was set up in 1991 in Hong Kong, numerous private and government health centres for women have been set up. A dedicated private Breast Care Centre was set up at the Hong Kong Sanatorium and Hospital (HKSH) in 1999. Over an 8-year period from October 1999 to September 2006, 14,596 women were screened, of whom 11,408 were asymptomatic. This study aims to produce the first report on breast screening experience in the largest cohort of asymptomatic Chinese women in the private sector. An overall malignancy detection rate of 2.3 per 1000 screens and a recall rate of 9.2% were found. Despite culture differences and differences in breast characteristics (denser and smaller breasts), breast screening is feasible and acceptable in the East.     

Risk of deep vein thrombosis following laparoscopic rectosigmoid cancer resection in chinese patients

OBJECTIVE: The aim of this study was to evaluate the incidence of postoperative deep vein thrombosis (DVT) in Chinese patients who underwent laparoscopic resection of rectal or sigmoid cancer in the absence of thromboprophylaxis. METHODS: Patients with adenocarcinoma of the sigmoid colon or rectum scheduled for laparoscopic resection were recruited. Neither chemoprophylaxis nor mechanical methods against DVT were employed. They were scheduled to have routine duplex ultrasound of both lower limbs perioperatively. RESULTS: In a 12-month period, 50 patients were recruited. Postoperative DVT occurred in 19 (38%) patients. None needed anticoagulation. Complete resolution of the thrombus was noted in 10 (53%) patients 12 weeks after operation, and in six patients 36 weeks after operation. Female sex was identified as being associated with a higher incidence of DVT. Age, smoking, preoperative neoadjuvant chemoirradiation, preoperative metastasis, duration of operation, conversion and postoperative complications did not appear to be risk factors for DVT. CONCLUSION: The incidence of asymptomatic calf vein DVT is relatively high after laparoscopic resection for rectosigmoid cancers in the Chinese population. However, complete resolution occurred without the use of anticoagulant therapy in the majority of cases. It is thus difficult to advocate the routine use of anticoagulant prophylaxis.     

Valve structure and survival in quinquagenarians having aortic valve replacement for aortic stenosis (+/-aortic regurgitation) with versus without coronary artery bypass grafting at a single US medical center (1993 to 2005)

The purpose of this study was to determine the effect of simultaneous coronary artery bypass grafting (CABG) and the influence of valve structure on both early and late survival in quinquagenarians having aortic valve replacement (AVR) for aortic stenosis (AS) (with or without aortic regurgitation). We analyzed survival and valve structure in 120 quinquagenarians having AVR for AS from 1993 through 2005 at Baylor University Medical Center, including 44 (37%) with and 76 (63%) without simultaneous CABG. Of the 120 patients, 2 (2%) died within 30 days of operation and none from 31 to 60 days postoperatively. Fifteen other patients (13%) died from >60 days to up to 13 years postoperatively. The unadjusted survival analysis showed that late survival was significantly better in the unicuspid/bicuspid valve structure group than in the tricuspid valve structure group (log-rank test p = 0.001), but that it was not affected by gender (male vs female), preoperative severity of the AS (transvalvular peak pressure gradient >50 vs < or =50 mm Hg), or by performance of CABG. The aortic valve was congenitally unicuspid in 18 patients (15%), congenitally bicuspid in 84 (70%), and 3-cuspid in 18 (15%). In conclusion, aortic valve structure affected the unadjusted late survival in quinquagenarians undergoing AVR for AS, but concomitant CABG, gender, and transvalvular peak systolic gradient had no effect.     

IgG4-related sclerosing lymphoplasmacytic pancreatitis and cholangitis mimicking carcinoma of pancreas and Klatskin tumour

Background: Autoimmune sclerosing pancreatitis is a well‐known disease entity for years, particularly recognizing the difficulty in distinguishing it from malignancy. Immunohistochemical study showed that immunoglobulin IgG4 staining was positive in plasma cells of some autoimmune pancreatitis or cholangitis. The term ‘autoimmune sclerosing pancreatocholangitis’ was used as it was believed that they belonged to a range of disease involving both pancreas and biliary tree. It may also be part of a systemic fibro‐inflammatory disease. Patients and Methods: All the patients suffering from immunoglobulin G4 (IgG4)‐related pancreatitis and cholangitis from May 2003 to September 2006 in Queen Elizabeth Hospital, Hong Kong were retrospectively studied. Results: A total of five patients with clinical diagnosis of IgG4‐related autoimmune pancreatitis or cholangitis were analysed. All presented with jaundice or abdominal pain, mimicking carcinoma. Two patients had major resection, two patients were diagnosed by intraoperative biopsy and one was based on serum IgG4 level. Conclusion: With the growing awareness of this relatively recently characterized clinical entity and its similar presentation to pancreatic carcinoma or bile duct cholangiocarcinoma, it is important for autoimmune sclerosing pancreatocholangitis to be included in the differential diagnosis of pancreaticobiliary disease. The management strategy has shown to be modified – from major resection to intraoperative biopsy and to the assay of serum IgG4 level without the necessity of histology confirmation.     

Transcatheter aortic valve replacement

Aortic stenosis is one of the most common valve pathologies found in adults. Aortic valve replacement via a sternotomy and cardiopulmonary bypass is the treatment of choice for patients with symptomatic aortic stenosis with very acceptable risk. However, patients with advanced age and multiple comorbidities carry significant operative risk; operative mortality as high as 25% was reported by many groups. Many of these patients are deemed nonsurgical for conventional aortic valve replacement by their cardiologists and surgeons. Novel surgical technique and valve technology offers an alternative treatment for aortic valve stenosis. Endovascular transcatheter aortic valve replacement is an emerging and promising technique, and may lower the risk in this subset of difficult patients.     

Treatment of periprosthetic humerus fractures associated with shoulder arthroplasty

The incidence of periprosthetic humerus fracture associated with shoulder arthroplasty is approximately 0.6% to 3%. Fractures of the humerus occur most often intraoperatively and are more common during total shoulder arthroplasty than hemiarthroplasty because of difficulties in gaining access to the glenoid. Osteopenia, advanced age, female sex, and rheumatoid arthritis are medical comorbid factors that may contribute to humerus fractures and associated delayed healing and poorer function. When the humeral prosthetic component is loose or the fracture line overlaps the majority of the length of the prosthesis, revision with a long-stem implant should be considered. When the fracture overlaps the tip of the prosthesis and extends distally, open reduction and internal fixation is recommended. When the fracture is completely distal to the prosthesis and satisfactory alignment at the fracture site can be maintained with a fracture brace, then a trial of nonsurgical treatment is recommended. The primary goals of treatment are fracture union and pain relief. Loss of glenohumeral motion has limited the successful treatment of this challenging problem.     

Primary osteoarthritis of the elbow: current treatment options

In the elbow, as in other joints, primary osteoarthritis is characterized by pain, stiffness, mechanical symptoms, and weakness. But primary osteoarthritis of the elbow is unique in that there is relative preservation of articular cartilage and maintenance of joint space, with hypertrophic osteophyte formation and capsular contracture. Medical treatment and physical therapy may be initiated in the early stages of the disease process. Surgical treatment options include arthroscopic osteocapsular débridement, open ulnohumeral arthroplasty, distraction interposition arthroplasty, and total elbow arthroplasty. The potential for instability and loosening following total elbow arthroplasty in the setting of primary osteoarthritis limits the clinical application of this procedure. This patient population is generally younger than that recommended for total elbow arthroplasty, and their higher functional demands have limited the long-term success of this treatment option. The improvement in arthroscopic débridement techniques is perhaps the greatest advancement in the treatment of osteoarthritis of the elbow in recent years.