Translational methods to detect asymmetries in temporal and spatial walking metrics in parkinsonian mouse models and human subjects with Parkinson's disease

Clinical signs in Parkinson's disease (PD), including parkinsonian gait, are often asymmetric, but mechanisms underlying gait asymmetries in PD remain poorly understood. A translational toolkit, a set of standardized measures to capture gait asymmetries in relevant mouse models and patients, would greatly facilitate research efforts. We validated approaches to quantify asymmetries in placement and timing of limbs in mouse models of parkinsonism and human PD subjects at speeds that are relevant for human walking. In mice, we applied regression analysis to compare left and right gait metrics within a condition. To compare alternation ratios of left and right limbs before and after induction of parkinsonism, we used circular statistics. Both approaches revealed asymmetries in hind- and forelimb step length in a unilateral PD model, but not in bilateral or control models. In human subjects, a similar regression approach showed a step length asymmetry in the PD but not control group. Sub-analysis of cohorts with predominant postural instability-gait impairment and with predominant tremor revealed asymmetries for step length in both cohorts and for swing time only in the former cohort. This translational approach captures asymmetries of gait in mice and patients. Application revealed striking differences between models, and that spatial and temporal asymmetries may occur independently. This approach will be useful to investigate circuit mechanisms underlying the heterogeneity between models.

Endoscopic retrograde cholangiopancreatography in elderly patients

BACKGROUND

the presentation of common bile duct disease, value of investigations and treatment outcome in elderly patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) were assessed.

METHODOLOGY

the clinical presentation, liver function tests, full blood counts, abdominal ultrasound and ERCP results were assessed retrospectively in 101 patients (59 women, 42 men; mean age 83 years, range 75-100) sequentially investigated for possible common bile duct disease.

RESULTS

59 patients had common bile duct gallstones, 35 had malignant biliary obstruction (13 with co-existing common bile duct stones) and seven had other outcomes. In the malignant-alone group 68% of those who had jaundice presented painlessly compared with 24% in the gallstones-alone group; 49% of the gallstones-alone group had pain compared with 28% of the malignant group. In the gallstones-alone group 43% had atypical presentations (non-specific symptoms or painless jaundice). Non-specific symptoms were found in 19% of the gallstones-alone group but in only 5% of the malignant group. Of the patients who had common bile duct stones, 18% had pancreatic or biliary malignancy. The co-existence of gallstones and malignancy was emphasized by eight patients in whom the clinical and ultrasound diagnosis was of common bile duct stones but malignancy was detected by ERCP. The sensitivity of ultrasound was 86% for detecting dilated common bile ducts was 86%, but only 69% for diagnosing gallstones within the common bile duct and 67% for diagnosing pancreatic masses. Ultrasound and ERCP were in agreement in 60 patients (60%). Endoscopic clearance of common bile duct gallstones was successful in 53 of 54 attempts (98%). Palliative ERCP treatment was performed in 30 patients who had malignant biliary obstruction and was successful in 22 (73%); in a further four patients (13%) an endoprothesis was successfully inserted percutaneously. The commonest complication of ERCP was cholangitis (four patients); pancreatitis and biliary perforation occurred in one patient each. Twenty-two patients (63%) who had malignancy died during follow-up, the mean survival being 11.3 weeks (range 3 days-2 years). Carcinoma of the ampulla was associated with a relatively good prognosis (three patients survived 18 months or more).

CONCLUSION

in elderly patients, common bile duct stones often present atypically and co-existence with malignancy is not unusual; ampullary carcinoma has a relatively good prognosis and ERCP is a safe and effective procedure in the management of biliary obstruction.