Perioperative risk factors for posterior ischemic optic neuropathy

Background:

Infarction of the optic nerve posterior to the lamina cribrosa, called posterior ischemic optic neuropathy (PION), is a condition that can result in profound bilateral blindness. Cases of PION treated at this institution and those described in the literature were analyzed to identify clinical features that profile those individuals at risk of PION in an attempt to identify major contributing factors that could be addressed prophylactically to enable effective prevention.

Study Design:

Salient clinical features in seven cases of PION diagnosed at the Doheny Eye Institute between 1989 and 1998 are compared with 46 cases of PION reported in the literature.

Results:

In the Doheny series there were six men and one woman aged 12 to 66 years (mean, 47 years). Five patients were status-post spine surgery, one was status-post knee surgery, and one had a bleeding stomach ulcer. Vision loss was simultaneously bilateral in six of seven patients (85.7%) and was apparent immediately after surgery. There were no abnormal retinal or choroidal findings including diabetic retinopathy, in any of the patients. Notable contributing factors were blood loss in all seven patients, ranging from 2,000 to 16,000 mL, with a drop in hematocrit of 9.5% to 19% (mean, 14%), and intraoperative systemic hypotension in all patients. Facial edema was a factor in three of six spine surgery patients (50%). Patients reported in the literature had a mean age of 50 years and were also predominantly men (34 of 46, 74%) who underwent spine surgery (30 of 46, 65.2%).

Conclusions:

Middle-aged men undergoing spine surgery with prolonged intraoperative hypotension and postoperative anemia and facial swelling are at risk of developing PION from hypovolemic hypotension. Avoiding or immediately correcting these contributory factors can reduce the incidence of PION.     

Laparoscopic-assisted vs open ileocolic resection for Crohn’s disease

BACKGROUND: The objective of this study was to compare laparoscopic-assisted ileocolic resection for Crohn's disease of the distal ileum with open surgery in two consecutive groups of patients. METHODS: From 1995 until 1998, 48 patients underwent open ileocolic resection at the Academic Medical Center (AMC) in Amsterdam, while 30 patients had laparoscopic-assisted ileocolic resection at the Leiden University Medical Center (LUMC). Patient characteristics, perioperative course, and recovery were compared. Differences between the groups were tested using Student's t-test for independent groups and chi-square tests when appropriate. RESULTS: The open and the laparoscopic patient groups were comparable for age, gender, body mass index (BMI), prior abdominal surgery, and length of resected bowel. The conversion rate was 6.6%. Laparoscopic operating times (138+/-SD 36 min) were significantly longer than those observed in the open group (104+/-SD 34 min). Discharge was significantly earlier in the laparoscopic group than the open group (5.7 vs 10.2 postoperative days, p<0.007). Postoperative morbidity did not differ significantly between the patients treated traditionally (14.6%) and laparoscopically (10%). CONCLUSION: Compared to open surgery, laparoscopic ileocolic resection for Crohn's disease is associated with similar morbidity rates, a shorter hospital stay, and improved cosmetic results, justifying the laparoscopic approach as the procedure of choice.     

Biliary‐enteric bypass in unresectable malignant hilar biliary obstruction: Kwong Wah Hospital experience

Objective : To evaluate the efficacy of biliary‐enteric bypass in the palliation of malignant hilar biliary obstruction. Materials and Methods : Records of 19 patients from 1995 to 1998 were reviewed. There were 13 patients with cholangiocarcinoma and 6 patients with carcinoma of the gallbladder. Single biliary‐enteric bypass had been performed in 13 of the patients; the rest had more than one biliary‐enteric anastomosis. Results : The 30‐day mortality was 21% (4/19 patients). Bile leakage occurred in 2 patients, leading, in both, to fatality. Excluding the 30‐day mortality, the median survival of patients with carcinoma of the gallbladder and cholangiocarcinoma was 116 days (43–200) and 202 days (47–1207), respectively. The mean hospital stay was 31 days (13–59) and all patients were discharged with their symptoms relieved and a drop in bilirubin of at least two‐thirds their pre‐operative level. The late complication rate was 26.7% (4/15 patients). Conclusion : Biliary‐enteric bypass is effective in the palliation of symptoms of patients suffering from unresectable hilar biliary obstruction, although it carries considerable mortality and morbidity. Stenting, rather than surgery, should be considered for patients with unresectable gallbladder cancer.      

Tuberculous meningitis in children

Between May 1988 and November 1992 the data from 52 patients with tuberculous meningitis (TBM) were noted down for their symptoms and signs, BCG vaccines, PPD tests; clinical, laboratory, radiologic and microbiologic findings. These data were discussed by means of literature knowledge. Cranial computed tomography (CT) demonstrated hydrocephalus (HC) in 98% of the patients. There was a statistically significant difference among the clinical stages on admission in respect to prognosis (P < 0.05). In addition, there was also a significant relationship between prognosis and HC (P < 0.05). However, we did not find any significant relationship between parenchymal involvement, basilar meningitis and prognosis (P > 0.05).     

Effects of BCG Vaccination on Evolution of Leprosy

Background

BCG vaccine is considered to have immunoprophylactic potential in leprosy. However controversy exists about the extent of prophylaxis it provides. In view of this, a study was undertaken to see the evolution of disease in established cases of leprosy who were already vaccinated with BCG and to compare it with the cases of leprosy who were not vaccinated with BCG.

Methods

114 newly diagnosed cases of leprosy were studied. Patients were divided into two groups-BCG vaccinated and non-vaccinated. Clinical diagnosis of leprosy was confirmed by bacteriological and histopathological studies in each case. All patients were given standard anti leprosy treatment and were evaluated monthly for a minimum period of one year.

Results

All the cases were males in the age group of 20 to 50 years. 25.4% of cases had received BCG vaccine and 74.6% were not vaccinated for the same. No significant difference was observed in the incidence of different types of leprosy in vaccinated and non-vaccinated groups. 25.9% cases in non-vaccinated group developed lepra reaction as compared to 13.8% in vaccinated group. The incidence of deformities and disabilities in vaccinated group was only 10.3% as against 18.8% in non-vaccinated group. The rate of bacillary clearance appeared faster in vaccinated group.

Conclusions

Although there is no significant difference in the pattern of different types of leprosy in BCG vaccinated and non-vaccinated cases, there is reduction in the incidence of reactions as well as deformities and disabilities in BCG vaccinated cases as compared to non-vaccinated cases.Key Words: BCG Vaccine, Leprosy     

Correction of Lower Limb Deformities Using Ilizarov's Technique

Background

India accounts for approximately 10 million orthopaedically handicapped children and adults with limb deformity. Ilizarov ring fixator could treat most of these deformities.

Methods

Twenty cases of deformities of lower limb managed with Ilizarov technique during period between March 2001 and February 2003 were studied.

Results

55% were in the age group of 11-30 years. Out of the 20 cases studied, 6 were congenital talipes equino varus, 8 were fixed flexion deformity of knee, 4 were equines deformity of the ankle and 2 were malunited fracture shaft of tibia.4 patients who had recurrence were operated for fixed flexion deformity of the knee. The main complication encountered was pin tract infection, which was seen in 15(75%) cases. In 16(80%) cases, the results were excellent with no recurrence of deformity and patients were able to walk independently. In 4 (20%) cases, recurrence was mild to moderate (10 to 20) but all of them were able to ambulate idependently and carry out their routine activities.

Conclusion

Ilizarov ring fixator is a superior compared to conventional methods for correction of deformities of lower limb.Key Words: Ilizarov method, Ligamentotaxis, Distraction     

Classification and knowledge discovery in protein databases

We consider the problem of classification in noisy, high-dimensional, and class-imbalanced protein datasets. In order to design a complete classification system, we use a three-stage machine learning framework consisting of a feature selection stage, a method addressing noise and class-imbalance, and a method for combining biologically related tasks through a prior-knowledge based clustering. In the first stage, we employ Fisher's permutation test as a feature selection filter. Comparisons with the alternative criteria show that it may be favorable for typical protein datasets. In the second stage, noise and class imbalance are addressed by using minority class over-sampling, majority class under-sampling, and ensemble learning. The performance of logistic regression models, decision trees, and neural networks is systematically evaluated. The experimental results show that in many cases ensembles of logistic regression classifiers may outperform more expressive models due to their robustness to noise and low sample density in a high-dimensional feature space. However, ensembles of neural networks may be the best solution for large datasets. In the third stage, we use prior knowledge to partition unlabeled data such that the class distributions among non-overlapping clusters significantly differ. In our experiments, training classifiers specialized to the class distributions of each cluster resulted in a further decrease in classification error.