The hidden risks of hearing tests and programmable ventriculoperitoneal shunt valves.

Programmable variable pressure valves were introduced in the 1980s, providing a non-invasive solution to post-operative alterations of the valve opening pressure to address problems of under or overdrainage. Since their increased use in the treatment of hydrocephalus, there have been case reports of unintentional alterations of the valve opening pressure following exposure to magnetic fields in everyday environments, from televisions to rollercoasters. Here we describe two cases of patients' programmable valves being altered following audiology assessments. We subsequently discuss some of the available research on the safety of these valves in various magnetic field strengths, alongside interim and updated recommendations made by the British Society of Audiologists with regards to testing of children with programmable shunts in place.

Influence of postural constraints on eye and head latency during voluntary rotations.

Redirecting gaze towards new targets often requires not only eye movements, but also synergistic rotations of the head, trunk and feet. This study investigates the influence of postural constraints on eye and head latency during voluntary refixations in the horizontal plane in 14 normal subjects. Three postural conditions were presented, (1) sitting in a chair using only eye and head movements, (2) standing without feet movements and (3) standing with feet movement. Head-eye reorientations towards eccentric un-predictable locations were performed towards ±45° and ±90° targets and back towards a central, spatially predictable target. Results showed that postural constraints affected eye latency but only when subjects knew the future location of the target (recentering "return" trials). Specifically, relatively longer eye latencies were observed when subjects had to turn their feet back towards the predictable central target. These findings suggest that the additional CNS processing required to reduce degrees of freedom during predictive motion introduces delays to the eye movement in order to efficiently assemble the components of a new motor synergy.

Risk factors for development of impaired renal function in Type 2 diabetes mellitus patients in primary care.

AIMS: To evaluate risk factors for the development of an impaired renal function, defined as a glomerular filtration rate (GFR) by Cockcroft-Gault formula < 50.5 ml/min, in primary care patients with Type 2 diabetes mellitus. METHODS: A case-control study of Type 2 diabetes mellitus patients with impaired renal function and age, sex and practice matched controls with Type 2 diabetes mellitus without impaired renal function in 10 Dutch family practices performing the Nijmegen Monitoring Project. Main outcome measure was the independent risk factors of impaired renal function. RESULTS: Eighty-seven individuals with impaired renal function were identified. The point prevalence of impaired renal function in the sample population on 31 March 2001 was 87/873 (10.0%; 95% confidence interval 7.0-15.1%). Of 87 cases, 23 (26.5%; 17.3-30.9%) were found to have impaired renal function at diagnosis. Conditional multiple logistic regression analysis revealed the following independent risk factors for the development of impaired renal function: duration of diabetes > or = 8 years (adjusted odds ratio 5.6 (2.5-12.5); P < 0.001), glomerular filtration rate by Cockcroft-Gault formula 50.5-80.5 ml/min at diagnosis [3.5 (1.5-8.1); P < 0.01] and existing macrovascular complications at diagnosis [2.6 (1.1-6.3); P < 0.01]. CONCLUSION: Duration of diabetes > or = 8 years, mild renal impairment at the time of diagnosis and existing macrovascular complications at the time of diagnosis are independent risk factors for the development of impaired renal function in white patients with Type 2 diabetes mellitus.