Spaceflight associated neuro-ocular syndrome . . . and other stories

BMJ 2018; 360 doi: https://doi.org/10.1136/bmj.k716 (Published 22 February 2018) Cite this as: BMJ 2018;360:k716

Trial, error, and medicine

Percutaneous cholecystolithotomy was an innovative technique by which gallstones were extracted through a small subcostal incision in the anterior abdominal wall. Although successful in a small number of patients, it was soon eclipsed by laparoscopic cholecystectomy and few people now remember it. An essay in Medical Humanities uses the story to make the point that, if we forget about blind alleys and dead ends, the history of medicine reads like a triumphal path to enlightenment rather than the reality of slow improvements by trial and error (Med Hum doi:10.1136/medhum-2016-011176).

Long term effects of traumatic brain injury

Epidemiologists linked Swedish national databases to investigate the association between traumatic brain injury and later dementia (Plos Medicine doi:10.1371/journal.pmed.1002496). They approached the data in different ways, setting up a retrospective cohort study, a case control study, and a study of sibling pairs discordant for brain injury. The results showed a consistently increased risk of dementia that persisted for many years after brain injury. Severe or multiple injury carried a higher risk than mild injury. In the sibling study, the one with a history of head injury was roughly twice as likely to develop dementia as the uninjured brother or sister.

Oral contraceptives and cancer risk

The American Diet and Health study, which has followed more than 100 000 women since the mid 1990s, reports that taking oral contraceptives seems to confer a small protective effect on the overall risk of cancer (Am J Epidemiol doi:10.1093/aje/kwx388). This was mainly explained by a substantial reduction in risk of ovarian and endometrial cancers, but there was also evidence of a reduced risk in non-Hodgkin’s lymphoma and kidney cancer. Oral contraceptive use had no association with most other types of cancer.

Omega 3 fatty acids

Many years ago, it was noticed that Inuit people, whose diet largely consisted of fish and seal meat, rarely experienced heart attacks. This gave rise to the hypothesis that marine derived fatty acids protected against vascular disease. The original observation was later shown to be unreliable but the idea lived on. A meta-analysis of 10 large trials involving nearly 80 000 people treated with omega 3 fatty acid supplements for around four years brings the story to an end (JAMA Cardiol doi:10.1001/jamacardio.2017.5205). It found no benefit of supplements on fatal or non-fatal coronary heart disease, or on any other major vascular event.

Women in medicine

Sexual harassment may not be as common in medicine as in some other professions but an essay in the Postgraduate Medical Journal (doi:10.1136/postgradmedj-2018-135554) cites evidence that nearly 60% of trainees have experienced it at some time. The author draws a parallel with bullying, where the perceptions of people in positions of power are different from those lower in the pecking order. What senior people think of as firm leadership appears to juniors as aggression or inappropriate delegation. In a similar way, what male clinicians may consider harmless flirtation can be seen by women as misogynistic, demeaning, and scary.

Space flight

The low gravity experienced in space flight produces many physiological challenges to the human body. Some, such as bone mineral loss and muscle atrophy, are well recognised but others are still being discovered. Among them is the recently named spaceflight associated neuro-ocular syndrome, which manifests as a deterioration in visual acuity and swelling of the optic nerve head. One theory is that it is the result of chronic mildly raised intracranial pressure but because intracranial pressure hasn’t yet been measured in space, no one is sure (Physiological Rev doi:10.1152/physrev.00017.2016).

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