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.