Effects of Early High-Dose Levothyroxine Treatment on Auditory Brain Event-Related Potentials at School Entry in Children with Congenital Hypothyroidism

Abstract

Aims: We tested whether brain event-related potentials (ERPs) are normal in children with congenital hypothyroidism (CH) after early high-dose levothyroxine treatment. Methods: Auditory ERPs were recorded in 33 normal controls and in 15 children with CH at 5 years 9/12. Based on bone maturation at diagnosis, the CH group was divided into severe (n = 8) and moderate (n = 7) subgroups. CH patients were treated at a median age of 14 days with a mean initial dose of levothyroxine of 11.6 µg/kg·day. Two ERP components (N100 and N200) were measured and clinical follow-up variables collected. Results: The functional anatomical and cognitive organisation of the auditory system, as revealed by the analyses of ERP measures, did not differ between CH and controls, or between severe and moderate CH subjects. However, N200 latency was globally longer in the CH than in the control group (p = 0.01) and was positively correlated with the over-treatment index (r = 0.61; p < 0.05) and verbal IQ. N200 amplitude was negatively correlated with initial dose (r = –0.74; p < 0.005). Conclusion: These data suggest that sensitive tools such as ERPs can reveal differences between CH and controls and relate these differences to the adequacy of treatment of CH.

Episodes of Overtreatment during the First Six Months in Children with Congenital Hypothyroidism and Their Relationships with Sustained Attention and Inhibitory Control at School Age

“…Simoneau et al [21] reported that the number of times the plasmatic thyrotropin (TSH) was above normal ranges during treatment was positively correlated to anxiety and inattention, while the number of times TSH was below normal correlated with inferior verbal punctuation. Also, Marti et al [22] found a greater latency in the auditory N200 component of cognitive potentials in the CH group as compared to healthy controls. Furthermore, the latency increased with excessive initial treatment, suggesting a potentially harmful effect of a high initial dose.…”

Hipotiroidismo congénito, la primera causa de retraso mental prevenible: un desafío para la medicina preventiva

“…El manejo farmacológico y clínico permite mejorar el IQ rápidamente en comparación con los niños que no han recibido tratamiento, incluso aquellos que han sido tratados podrían alcanzar un crecimiento, desarrollo y peso normal para su edad 45 . Además, se ha informado mejora en el estado de ánimo y la función neuropsicológica en pacientes que han sido tratados con una combinación de hormonal T4 y T3 49 ; y mejora en los cambios del desarrollo psicomotor y del lenguaje con el empleo oportuno y temprano de levotiroxina 46,48 . Dentro de las consecuencias negativas del tratamiento por ejemplo podemos encontrar variaciones en el peso que aún no se han correlacionado con niveles hormonales de THS; y compromiso de la inteligencia, donde se evidencian disminuciones del IQ, de 5 a 10 puntos 47 .…”

Detección de información oculta mediante potenciales relacionados con eventos

“…Es un indicador muy sensible pero inespecífico porque se obtiene independientemente de la modalidad sensorial de los estímulos: visual o auditivo. Hansenne (2000) expone una amplia gama de usos del P300 para la investigación clínica, y usualmente es un indicador que se usa para detectar daños sutiles en los procesos atencionales (Alonso et al, 2002;Marti et al, 2006).…”