Biomedical subjects
Publications and source records attributed to J L Emery.
A girl aged 1 year died of acute haemorrhagic pancreatitis while taking sodium valproate. Necropsy showed widespread vascular disease that may have contributed to the onset of pancreatitis. Previous reports of pancreatitis in children receiving valproic acid are reviewed and although the association is rare, a causal relation between pancreatitis and valproic acid seems to have been established.
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This report describes six cases of achondroplasia, four of whom died unexpectedly in early childhood. Clinical details and pathological findings are reported. Unexpected death seems to be a feature of children with achondroplasia, and appears to be related to brain-stem lesions secondary to deformities of the foramen magnum and posterior fossa.
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A detailed pathological and psychosocial study was made of all postperinatal (8 days-2 years) deaths in Sheffield during a 2-year period. The cause of death was classified from the point of view of possible prevention. Of the total of 65 deaths, 35 were unpreventable after the perinatal period, but 9 might have been preventable before birth. Of the 30 other deaths, 20 had evidence of possible treatable disease, and for the majority of these adverse social factors could be identified. Proved non-accidental injury occurred in 2 children and in 3 others there was a high degree of suspicion of 'gentle battering'. Only in 4 children was death unexplained and this apparently represents the local true unexplained cot death rate of 0.16/1000 births.
A quantitative study of the trachea has been made in 452 children with apparently normal tracheas ranging from 28 weeks' gestation to 14 years. In the neonatal period the trachea is funnel shaped with the upper end wider than the lower end. It becomes cylindrical with increasing age. The ratio of cartilage to muscle remains constant throughout childhood. The trachea appears to grow at a greater rate, in relation to crown-rump length, during the age of 1 month to 4 years than in utero or around puberty. Normal measurements for formalin-fixed tracheas related to crown-rump length are presented.
Examination of the records of hospital admissions and all deaths among the 40,544 Sheffield children who were aged less than two years in the period 1975-79 revealed 475 children admitted with their first febrile convulsion and 50 children who presented as cot deaths. Rectal temperatures taken before refrigeration were traced for 24 of the latter. 10 of these 24 children had temperatures in excess of 38 degrees C and 5 were greater than 40 degrees C. There was a transition in age at presentation between the two groups, with most cot deaths occurring before six months of age and febrile convulsions after that age. No time-based clustering between the date of presentation with cot death or febrile convulsion was found to suggest a single aetiological agent. It is suggested that febrile convulsions and some inexplicable sudden infant deaths may be equivalent responses to a febrile stimulus, but with a different outcome because of the difference in age of occurrence. A common mechanism could be thermolabile syncope which, in the susceptible younger infant, leads to irreversible cerebral ischaemia. The rectal temperature should be taken as soon as possible in all cot deaths. An aberration of a vagally mediated reflex may be responsible for some cot deaths.
The morbidity pattern, based on hospital admissions for a complete year's cohort of all children born in Sheffield 1975-6, was studied. In many children the diagnosis given on admission had changed by the time they were discharged from hospital. About one-quarter of children under age 6 months were admitted for social reasons. Despite a decreasing birth rate the admission rate had increased, with an overall admission rate of 11.2% of all births. The rates and ages at which children are admitted varied greatly according to the month of birth. This is an important factor if cohort studies from different places are being compared.
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A diet which is marginally deficient in the vitamin biotin may cause sudden unexpected death of young broiler chickens when they are exposed to stress. Chickens affected with this disorder have low levels of biotin in their livers. In conditions of biotin insufficiency, we postulate that a similar disorder, triggered by mild stress, may occur in the human infant. We have now used a radiochemical technique to measure the biotin content of 204 livers obtained from infants at autopsy. The levels of biotin in the livers of infants who had died of sudden infant death syndrom (SIDS; cot death) were significantly lower than those in livers of infants of similar age, who had died of explicable causes. These findings support an association of biotin with SIDS.
The tracheas of 74 children with respiratory disorders were analysed and compared with the tracheas of children with no respiratory symptoms. The test tracheas showed an increase in the size of the lumen and the length of the cartilage and membrane, the increase in the length of membrane being particularly striking. The relation between age at onset and duration of symptoms was uncertain.
The structure of the membranous wall of the trachea was studied in 560 tracheas from children aged 24 weeks of gestation to 10 years. The transverse muscle fibres are uniformly arranged. This is in marked contrast to the longitudinal smooth muscle which varies throughout the entire tracheal length. In 16% of tracheas, the longitudinal muscle was absent, while in the other 84% its distribution was variable with the muscle being present in the lower half of the trachea in approximately 70% of cases. It is suggested that the longitudinal muscle may be active in preserving the stability of the tracheal wall, preventing tracheal collapse and obliteration of the lumen, particularly in the intrathoracic part of the trachea.
An attempt was made to obtain normal values of the sizes of glomeruli in the fetus and child. The kidneys of 117 children from 12 weeks gestation to 5 years of age were measured and the difference in size between the juxta-arcuate, mid-cortical and superficial glomeruli was examined. Juxta-arcuate and mid-cortical glomeruli showed an initial decrease in size from 12 to 20 weeks gestation. This was not seen in the most superficial glomeruli. After the initial decrease, the juxta-arcuate and superficial glomeruli remained at the same size until birth. The superficial glomeruli remained the same size from 12 weeks gestation to term. There was an immediate increase in size after birth in all three groups which slowed down after 2 years, when all three groups became the same size. The changes in size of the juxta-arcuate and mid-cortical glomeruli may be explained by functional demand.
The death certificates and necropsy reports of the 1115 Sheffield infants who died under 2 years of age in 1969-78 were examined. This study showed the apparent disappearance of deaths with hypernatraemia and in particular deaths presenting as cot deaths. The fall in incidence may be as much the result of an intensive local campaign on child care and infant feeding as of the change in the composition of dried milk for baby feeding.
Children who die unexpectedly in infancy often have symptoms of illness before death. Survey data are used to evaluate risks associated with symptoms. There is a 1 in 50 chance of unexpected infant death occurring in the next 9 days when two or more symptoms occur in infants defined to be at high risk by a discriminant score. The score is based on data collected on all infants at birth and by health visitors at 1 month. This system would identify 50% of cot deaths and provides a basis for prospective physiological studies.
Forty tracheas from children with tracheo-oesophageal fistulae were histologically analysed for structural deformity. Thirty (75%) had a deficiency of cartilage; 24 (60%) showed an increase in the length of the transverse muscle, and 26 (65%) had a longer than average internal perimeter. Only six tracheas were entirely normal. The position of the fistula bore little relationship to the abnormalities found. Since in only nine patients were abnormalities restricted to the site of the fistula, we believe that careful examination of the whole length of the trachea is needed at the time of surgery to determine the extent of the anomaly and to anticipate tracheal problems. This is also relevant to autopsy studies and to elucidate the cause of death.