Colon perforation following percutaneous nephrostomy and renal calculus removal

Two patients had colonic perforation as a result of percutaneous nephrostomy placement followed by track dilatation and renal calculus removal. We present the technical aspects of nephrostomy placement and stone removal, as well as the clinical diagnosis and management of these cases. Both patients recovered well with conservative therapy and required no surgical intervention. This report reviews the anatomic considerations for percutaneous nephrostomy in patients undergoing renal stone removal.     

Correlations of regional cerebral metabolism with memory performance and executive function in patients with herpes encephalitis or frontal lobe lesions

Cerebral [18F]fluorodeoxyglucose positron emission tomography (18FDG-PET) data from patients suffering amnesia following herpes encephalitis (n=7) or frontal lobe pathology (n=14) were compared with data from age-matched nonamnesic subjects (n=10). All subjects received structural MRI, resting 18FDG-PET scans, and neuropsychological evaluation. PET data were analyzed using complementary statistical parametric mapping and region-of-interest methods. Differential patterns of hypometabolism were found in patients relative to healthy controls. Factor analysis of the neuropsychological data revealed that memory performance was associated with retrosplenial and medial temporal metabolism, and executive function was associated with dorsolateral frontal metabolism. The association between memory performance and retrosplenial metabolism remained statistically significant after accounting for measures of cerebral atrophy using MRI. The significance of the retrosplenium as a major relay station between the thalamus and the medial temporal and frontal lobes--sensitive to changes in either--is discussed in the light of the findings.     

Minimal risk as an international ethical standard in research

Classifying research proposals by risk of harm is fundamental to the approval process and the most pivotal risk category in most regulations is that of "minimal risk." If studies have no more than a minimal risk, for example, a nearly worldwide consensus exists that review boards may sometimes: (1) expedite review, (2) waive or modify some or all elements of informed consent, or (3) enroll vulnerable subjects including healthy children, incapacitated persons and prisoners even if studies do not hold out direct benefits to them. The moral and social purposes behind this threshold are discussed along with relevant views from the National Commission, NBAC, NHRPAC, Grimes v. Kennedy Krieger Institute, The Nuremberg Code, and The WMA's Declaration of Helsinki. Representative policies from Australia, Canada, South Africa, the U.S., and CIOMS are reviewed revealing different understandings of this sorting threshold. Six of nine frequently cited interpretations of "minimal risk" are untenable. The "absolute" interpretation of the "routine examination" standard is defended as best.     

Why semantic dementia drives you to the dogs (but not to the horses): A theoretical account

This paper describes a patient (IH) with semantic dementia and severe impairment in all semantic categories except for numerical knowledge, which was preserved. IH showed a severe deficit in reading and writing non-number words (e.g., candle, juice) and nonwords, and preservation of reading and writing number words (e.g., one, forty) and numerals (e.g., 1, 40). IH's pattern of performance can be explained by the combination of a selective sparing of one semantic category--i.e., numbers--with a total deficit of nonsemantic processes for mapping letters and sounds. As number was the only spared semantic category in the presence of these other nonsemantic deficits, it follows that the semantic route is sufficient for accurate reading and spelling. Our data clarify the nature of reading and writing processes and support the functional and neuroanatomical independence of the number domain.     

Retrograde amnesia and the volume of critical brain structures

There are many controversies concerning the structural basis of retrograde amnesia (RA). One view is that memories are held briefly within a medial temporal store ("hippocampal complex") before being "consolidated" or reorganised within temporal neocortex and/or networks more widely distributed within the cerebral cortex. An alternative view is that the medial temporal lobes are always involved in the storage and retrieval (reactivation) of autobiographical memories (multiple trace theory). The present study used quantitative magnetic resonance imaging (MRI) in 40 patients with focal pathology/volume loss in different sites, to examine the correlates of impairment on three different measures of RA. The findings supported the view that widespread neural networks are involved in the storage and retrieval of autobiographical and other remote memories. Brain volume measures in critical structures could account for 60% of variance on autobiographical memory measures (for incidents and facts) in diencephalic patients and for 60-68% of variance in patients with frontal lesions. Significant correlations with medial temporal lobe volume were found only in the diencephalic group, in whom they were thought to reflect thalamic changes, but not in patients with herpes encephalitis or hypoxia in whom the temporal lobes were particularly implicated. The latter finding fails to support one of the main predictions of multiple trace theory, as presently expounded.     

Diversity, trust, and patient care: affirmative action in medical education 25 years after Bakke

The U.S. Supreme Court's seminal 1978 Bakke decision, now 25 years old, has an ambiguous and endangered legacy. Justice Lewis Powell's opinion provided a justification that allowed leaders in medical education to pursue some affirmative action policies while at the same time undermining many other potential defenses. Powell asserted that medical schools might have a "compelling interest" in the creation of a diverse student body. But Powell's compromise jeopardized affirmative action since it blocked many justifications for responding to increases in political opposition and legal challenges. The Bakke decision and its moral background and legal legacy are traced and analyzed. Despite recent legal setbacks, the framework sketched by Powell can be used to defend diversity in medical education both morally and legally as a "compelling state interest." Because trust is a central component of the physician-patient relationship and a prerequisite to the profession's ability to provide effective medical care, the state has a compelling interest in training physicians with whom patients can feel comfortable and safe if the population is (1) distrustful; (2) underserved; (3) faces significant discrimination in the allocation of benefits, goods and services and (4) affirmative action programs would be likely to promote their trust in the system. Similar narrowly-tailored arguments could be used in other professions and for other groups. Bakke is an important background for the pending Grutter case.