Neurological Aspects of Cretinism in Qinghai Province

Halpern, J-P; Morris, John G.; Boyages, Steven; Maberly, G. F.; Eastman, Creswell J; Jin, Chun-Shun; Zl, Wang; Lim, J-L; Duan, Yu; You, Cheng

doi:10.1007/978-1-4613-0765-5_22

Cited by 4 publications

(4 citation statements)

References 3 publications

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“…Hearing loss is a common neurologic disease found in humans with different types of hypothyroidism such as cretinism ( Trotter, 1960 ; DeLong et al, 1985 ; Morreale de Escobar et al, 2000 ), congenital hypothyroidism ( Vanderschueren-Lodeweyckx et al, 1983 ; Rovet et al, 1996 ) and resistance to thyroid hormone also known as Refetoff syndrome ( Refetoff et al, 1967 ). Deafness caused by hypothyroidism is often due to irreversible damage of the Corti’s organ ( Knipper et al, 2000 ) and to abnormal development of the brain stem ( Halpern et al, 1989 ; Ma et al, 1989 ). Impaired hearing ( Navarro et al, 2015 ) and the abnormal radial distribution of callosal auditory neurons ( Berbel et al, 1993 ) have been found in chronic hypothyroid rats.…”

Section: Discussionmentioning

confidence: 99%

Transient Hypothyroidism During Lactation Alters the Development of the Corpus Callosum in Rats. An in vivo Magnetic Resonance Image and Electron Microscopy Study

et al. 2020

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Magnetic resonance imaging (MRI) data of children with late diagnosed congenital hypothyroidism and cognitive alterations such as abnormal verbal memory processing suggest altered telencephalic commissural connections. The corpus callosum (CC) is the major inter-hemispheric commissure that contra-laterally connects neocortical areas. However, in late diagnosed neonates with congenital hypothyroidism, the possible effect of early transient and chronic postnatal hypothyroidism still remains unknown. We have studied the development of the anterior, middle and posterior CC, using in vivo MRI and electron microscopy in hypothyroid and control male rats. Four groups of methimazole (MMI) treated rats were studied. One group, as a model for early transient hypothyroidism, was MMI-treated from postnatal day (P) 0 to P21; some of these rats were also treated with L-thyroxine (T4) from P15 to 21. Another group modeling chronic hypothyroid, were treated with MMI from P0 to 150 and from embryonic day 10 to P170. The results obtained from these groups were compared with same age control rats. The normalized T2 signal obtained using MRI was higher in MMI-treated rats and correlated with a low number and percentage of myelinated axons. The number and density of myelinated axons decreased in transient and chronic hypothyroid rats at P150. The g-ratio (inner to outer diameter ratio) and the estimated conduction velocity of myelinated axons were similar between MMI-treated and controls, but the conduction delay decreased in the posterior CC of MMI-treated rats compared to controls. These data show that early postnatal transient and chronic hypothyroidism alters CC maturation in a way that may affect the callosal transfer of information. These alterations cannot be reversed after delayed T4-treatment. Our data support the findings of neurocognitive delay in late T4-treated children with congenital hypothyroidism.

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Section: Discussionmentioning

confidence: 99%

Transient Hypothyroidism During Lactation Alters the Development of the Corpus Callosum in Rats. An in vivo Magnetic Resonance Image and Electron Microscopy Study

et al. 2020

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“…In humans, hearing loss has been found in cretinism (Trotter, 1960 ; DeLong et al, 1985 ; Morreale de Escobar et al, 2000 ), congenital in congenital hypothyroidism (Vanderschueren-Lodeweyckx et al, 1983 ; Rovet et al, 1996 ), and in Refetoff syndrome (Refetoff et al, 1967 ). Deafness may be complete in as many as 50% of patients suffering cretinism, in which no cochlear or brain stem response is seen (Halpern et al, 1989 ; Ma et al, 1989 ). Cochlear impairment and hearing loss with a decrease in hearing threshold by 20–60 dB was found in five different types of thyroid hormone receptor mutants (Ng et al, 2001 ; Rüsch et al, 2001 ).…”

Section: Discussionmentioning

confidence: 99%

Gestational and early postnatal hypothyroidism alters VGluT1 and VGAT bouton distribution in the neocortex and hippocampus, and behavior in rats

et al. 2015

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Thyroid hormones are fundamental for the expression of genes involved in the development of the CNS and their deficiency is associated with a wide spectrum of neurological diseases including mental retardation, attention deficit-hyperactivity disorder and autism spectrum disorders. We examined in rat whether developmental and early postnatal hypothyroidism affects the distribution of vesicular glutamate transporter-1 (VGluT1; glutamatergic) and vesicular inhibitory amino acid transporter (VGAT; GABAergic) immunoreactive (ir) boutons in the hippocampus and somatosensory cortex, and the behavior of the pups. Hypothyroidism was induced by adding 0.02% methimazole (MMI) and 1% KClO4 to the drinking water starting at embryonic day 10 (E10; developmental hypothyroidism) and E21 (early postnatal hypothyroidism) until day of sacrifice at postnatal day 50. Behavior was studied using the acoustic prepulse inhibition (somatosensory attention) and the elevated plus-maze (anxiety-like assessment) tests. The distribution, density and size of VGluT1-ir and VGAT-ir boutons in the hippocampus and somatosensory cortex was abnormal in MMI pups and these changes correlate with behavioral changes, as prepulse inhibition of the startle response amplitude was reduced, and the percentage of time spent in open arms increased. In conclusion, both developmental and early postnatal hypothyroidism significantly decreases the ratio of GABAergic to glutamatergic boutons in dentate gyrus leading to an abnormal flow of information to the hippocampus and infragranular layers of the somatosensory cortex, and alter behavior in rats. Our data show cytoarchitectonic alterations in the basic excitatory hippocampal loop, and in local inhibitory circuits of the somatosensory cortex and hippocampus that might contribute to the delayed neurocognitive outcome observed in thyroid hormone deficient children born in iodine deficient areas, or suffering from congenital hypothyroidism.

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“…Almost all are deaf mutes and are afflicted with the following neurological defects: (a) impaired voluntary motor activity, usually involving paresis or paralysis of pyramidal origin, chiefly in the lower limbs, with hypertonia, clonus, and plantar cutaneous reflexes in extension. Extrapyramidal signs are occasional, (b) FIG (12,107,108,133,174,203) emphasized the impariment of the extrapyramidal tract in neurological endemic cretinism. In these areas, the pattern of neurological deficit included proximal spasticity and rigidity involving the lower extremities more than the upper, with increased knee jerks and adductor jerks.…”

Section: Complicationsmentioning

confidence: 99%

“…In an attempt to present a unifying hypothesis for the etiopathogenesis of endemic cretinism, and based on very careful and extensive studies of endemic cretinism as seen in China and Indonesia (16,69,70,107,108), it has been proposed that the clinical picture of endemic cretinism results from the product of two pathophysiological events, both resulting from iodine deficiency: the first event is maternal or/and fetal hypothyroidism. It occurs in all cretins and results in the neurological features of the disorder.…”

Section: Complicationsmentioning

confidence: 99%

The Disorders Induced by Iodine Deficiency

Delange¹

1994

Thyroid

561

447

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This paper reviews present knowledge on the etiology, pathophysiology, complications, prevention, and therapy of the disorders induced by iodine deficiency. The recommended dietary allowances of iodine are 100 micrograms/day for adults and adolescents, 60-100 micrograms/day for children aged 1 to 10 years, and 35-40 micrograms/day in infants aged less than 1 year. When the physiological requirements of iodine are not met in a given population, a series of functional and developmental abnormalities occur including thyroid function abnormalities and, when iodine deficiency is severe, endemic goiter and cretinism, endemic mental retardation, decreased fertility rate, increased perinatal death, and infant mortality. These complications, which constitute a hindrance to the development of the affected populations, are grouped under the general heading of iodine deficiency disorders (IDD). At least one billion people are at risk of IDD. Iodine deficiency, therefore, constitutes one of the most common preventable causes of mental deficiency in the world today. Most of the affected populations live in mountainous areas in preindustrialized countries, but 50 to 100 million people are still at risk in Europe. The most important target groups to the effects of iodine deficiency from a public health point of view are pregnant mothers, fetuses, neonates, and young infants because the main complication of IDD, i.e., brain damage resulting in irreversible mental retardation, is the consequence of thyroid failure occurring during pregnancy, fetal, and early postnatal life. The main cause of endemic goiter and cretinism is an insufficient dietary supply of iodine. The additional role of naturally occurring goitrogens has been documented in the case of certain foods (milk, cassava, millet, nuts) and bacterial and chemical water pollutants. The mechanism by which the thyroid gland adapts to an insufficient iodine supply is to increase the trapping of iodide as well as the subsequent steps of the intrathyroidal metabolism of iodine leading to preferential synthesis and secretion of triiodotyronine (T3). They are triggered and maintained by increased secretion of TSH, which is ultimately responsible for the development of goiter. The acceleration of the main steps of iodine kinetics and the degree of hyperstimulation by TSH are much more marked in the pediatric age groups, including neonates, than in adults, and the development of goiter appears as an unfavorable side effect in the process of adaptation to iodine deficiency during growth. The most serious complication of iodine deficiency is endemic cretinism, a syndrome characterized by irreversible mental retardation together with either a predominant neurological syndrome or predominant hypothyroidism, or a combination of both syndromes.(ABSTRACT TRUNCATED AT 400 WORDS)

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Neurological Aspects of Cretinism in Qinghai Province

Cited by 4 publications

References 3 publications

Transient Hypothyroidism During Lactation Alters the Development of the Corpus Callosum in Rats. An in vivo Magnetic Resonance Image and Electron Microscopy Study

Transient Hypothyroidism During Lactation Alters the Development of the Corpus Callosum in Rats. An in vivo Magnetic Resonance Image and Electron Microscopy Study

Gestational and early postnatal hypothyroidism alters VGluT1 and VGAT bouton distribution in the neocortex and hippocampus, and behavior in rats

The Disorders Induced by Iodine Deficiency

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