Endemic cretinism in the Andean region of Ecuador

Growing up different in Neolithic China: A contextualised case study and differential diagnosis of a young adult with skeletal dysplasia

This paper presents a case study of a young adult from the late Neolithic Yangshao cultural period site (∼3300-2900 years BC) of Guanjia () located in Henan Province on the Central Plains of China, who has evidence for skeletal dysplasia characterised by proportional stunting of the long bones and a small axial skeleton, generalised osteopenia, and non-fusion of epiphyses. We provide a detailed differential diagnosis of skeletal dysplasia with paediatric onset and conclude that this is likely a form of hypopituitarism or hypothyroidism, an extremely rare finding within the archaeological context. This paper highlights the issues of distinguishing the forms of proportional dwarfism in palaeopathology because of the considerable variation in manifestation of these conditions. Finally, we assess whether there were any health and social implications for this person and community through the consideration of a bioarchaeology of care approach across the lifecourse, burial context, and information on social perceptions of 'difference' in the community. ：： （3300～2900）。，，，，。，，。。，。，、、""，。.

Endemic cretinism: toward a unifying hypothesis

Based on our data, the clinical picture of endemic cretinism results from the product of two pathophysiological events. Both events share a common feature, namely iodine deficiency, but act at different points in time. The first event occurs in all cretins and represents the prenatal action of thyroid hormone deficiency on brain development, transmitted vertically from mother to fetus, resulting in the neurological disorder of endemic cretinism. A consistent pattern and intensity of neurological, intellectual, and audiometric deficit is common to and equally present in all types of endemic cretin. The nature of these deficits points to an intrauterine insult to the developing fetal nervous system around the time of the midtrimester. The second event represents the postnatal action of thyroid hormone deficiency on somatic as well as brain development. Whereas previous workers had attributed the differences in the clinical presentation of endemic cretinism to the presence or absence of neurological features (i.e. prenatal hypothyroidism), the distinction between the types of endemic cretin can be related to the length and severity of postnatal thyroid hormone deficiency. Endemic cretins with predominant neurological features have had only transient hypothyroidism in the postnatal period, evidenced by their near normal thyroid function and by a lack of hypothyroid clinical features. By contrast, cretins with marked myxedematous features were characterized by permanent and severe postnatal thyroid hormone deficiency. These cretins, in addition to signs of neurological damage, were typically dwarfed, sexually immature, with marked clinical features of myxedema. This second event, influenced by the thyroid gland's morphologic response to its environment (goiter or thyroid atrophy), dictates the final clinical outcome. In conclusion, our hypothesis states that the clinical expression of endemic cretinism is determined by the sum of two pathophysiologic processes. The first process is fetal hypothyroidism which results in the neurological damage of the disorder and the second process is the duration and magnitude of postnatal hypothyroidism which dictates the final clinical appearance.

Clinical pattern and the genetics of the fetal iodine deficiency disorder (endemic cretinism): results of a field study in Highland Ecuador

The clinical manifestations of various degrees of mental retardation, spastic diplegia, and deaf mutism are known as the neurologic type of endemic cretinism (EC), occurring in countries with high goiter endemicity. Maternal iodine deficiency has been established as the major cause in EC, whereas a genetic predisposition has not been well-documented. Genetic data on 70 families with EC from Highland Ecuador are reported. A segregation analysis of 49 fully classified families yielded an estimate of P = 0.245 (var [P] = 0.00167). Half-sibs were all unaffected and no significant birth order effect was observed among 101 probands. The data indicate an autosomal recessive predisposition as a major etiological factor. Because the neurologic type of EC represents a defined section of the spectrum of iodine deficiency disorders (IDD), the term fetal iodine deficiency disorder (FIDD) rather than cretinism is suggested. The clinical findings in 70 patients were used to delineate the minimal diagnostic criteria of FIDD.

Endemic goitre and iodine deficiency disorders--aetiology, epidemiology and treatment

Disorders caused by iodine deficiency continue to be a major health problem in many underdeveloped areas of the world. The most significant is the impaired mental and physical development which occurs as a result of iodine deprivation early in life. Individuals in affected communities show a spectrum of abnormalities which can be attributed to two interacting pathological processes. Fetal hypothyroidism in the first and early second trimester predominantly affects the developing nervous system causing deaf-mutism and mental retardation. If hypothyroidism occurs in the early postnatal period the main abnormalities are growth stunting and related somatic abnormalities. Subclinical deficits of intellectual and motor development may also be found in apparently normal individuals living in affected areas. Although dietary iodine deficiency is clearly the major aetiological factor in both endemic goitre and cretinism, cofactors such as goitrogens, other trace element deficiencies and immunological mechanisms may greatly modify the expression of these disorders. Iodine supplementation programmes form the basis of the public health strategy in combatting these disorders. Where the iodization of foodstuffs is not feasible, an alternative is the use of iodine containing oil which can be given orally or intramuscularly to provide a long-lasting supply of iodine.

Comparative study of neurological and myxoedematous cretinism associated with severe iodine deficiency

The clinical and biochemical features of myxoedematous and neurological cretinism were studied in an endemic goitre area in Algeria (goitre prevalence 51.3%; endemic cretinism 1.1%; mean urinary iodine level 127.6 nmol/l). When comparing the data collected in six different villages of the area, significant negative correlations were found between the decrease in urinary iodide and iodide/thiocyanate ratio (I/SCN) and the increase in prevalences of visible goitres, endemic cretinism and transient neonatal hypothyroidism. The cretins were divided on clinical signs into two groups: myxoedematous (MC) and neurological (NC) cretinism. Differences were noted in the neurological signs and the type of deafness encountered in both types. Although some overlap did exist, proximal spasticity and rigidity were characteristic of NC. The hormonal profiles of the two groups, including TRH tests, were clearly different. The two groups were similar with regard to the percentage of palpable thyroids, the absence of antimicrosomal and anti-thyroglobulin antibodies, seropositive viral antibodies and thiocyanate concentrations in serum and urine. Thus it is unlikely that these factors have any significant aetiological role in NC. The data collected in the general population in this area and those obtained in the mothers of the myxoedematous and neurological cretins support the hypothesis that the neurological signs are the result of hypothyroxinaemia in the mothers and the fetus at different periods of pregnancy. They could be aggravated by neonatal hypothyroidism, which may be transient in NC and permanent in MC.

Permanent defects in rat peripheral auditory function following perinatal hypothyroidism: determination of a critical period

Rats were treated with propylthiouracil (PTU) for 10-day periods beginning at different ages. Daily injections of L-thyroxine (T4) were administered concurrently with PTU to a group of rats which served as one control group. Peripheral auditory function was evaluated by the brainstem response audiometry (BSRA) technique performed at 12, 16, 25 and 120 days of age. PTU treatment significantly increased wave I latency (cochlear nerve compound action potential) in adult rats when administered from 3 days before delivery through 6 days of age, but was without permanent effect (wave I latencies and thresholds) when administered for 10 days starting at 10 days after birth. T4 replacement during the first 10 postnatal days prevented permanent abnormalities. These data suggest that the period of greatest vulnerability to thyroid hormone depletion in the peripheral auditory system extends from at least 3 days before delivery through between 5 and 10 days of age.

Iodine deficiency disorders (IDD) and their eradication

Disorders resulting from severe iodine deficiency affect more than 400 million people in Asia alone. These disorders include stillbirths, abortions, and congenital anomalies; endemic cretinism, characterised most commonly by mental deficiency, deaf mutism, and spastic diplegia and lesser degrees of neurological defect related to fetal iodine deficiency; and impaired mental function in children and adults with goitre associated with subnormal concentrations of circulating thyroxine. Use of the term iodine deficiency disorders, instead of "goitre", would help to bridge the serious gap between knowledge and its application. Iodised salt and iodised oil (by injection or by mouth) are suitable for the correction of iodine deficiency on a mass scale. A single dose of iodised oil can correct severe iodine deficiency for 3-5 years. Iodised oil offers a satisfactory immediate measure for primary care services until an iodised salt programme can be implemented. The complete eradication of iodine deficiency is therefore feasible within 5-10 years.

Foetal thyroidectomy and brain development in the sheep

Sheep foetuses were surgically thyroidectomized at 50-60 days gestation, when thyroid function begins, and the pregnancy was then allowed to continue until 90, 120 or 150 days (term). At these times the foetuses were removed by caesarean delivery, exsanguinated, weighed and dissected. The central nervous system was divided--cerebral hemispheres, brain stem, cerebellum and spinal cord for subsequent analysis. Comparison was made with sham operations on seven foetuses. Thyroidectomy led to a fall in body weight (24.7%) and brain weight (11.7%) at 120 days and 150 days, 31.1% and 24.5% respectively. The hemispheres showed the greatest change and the cerebellum the least. DNA and protein contents were reduced in the hemispheres and cerebellum at 150 days, while in the brain stem and spinal cord the DNA content was not significantly affected. Protein content was, however, reduced indicating a reduced cell size, but not a reduced cell number as in the other two regions. Somatic changes included reduced wool growth, delayed osseous development in the limbs (X-ray assessment) a reduced heart weight (39.1%) and an increased pituitary weight (48.1%). The thyroidectomized lambs failed to survive for more than a few hours after birth or caesarean delivery at 150 days. The findings indicate significant effects of foetal thyroidectomy on brain development in the sheep late in pregnancy along with other evidence of foetal hypothyroidism.