The ability to sustain attention was studied using continuous performance tasks in 48 children with early treated congenital hypothyroidism (CH) and 35 healthy controls at the University of Groningen, The Netherlands. In 38 patients with T4 levels <50 nmol/1 as neonates, performance of a computer-paced task declined over time, suggesting impairment of sustained attention. In a self-paced task, an initial performance decline was followed by an improvement in the final stages, this pattern being most pronounced in the low T4 group, reflecting a greater performance variability over time and a problem with sustained attention. The performance of the 10 children with intermediate T4 levels (=/> 50 nmol/1 as neonates) fell between the control group and the low T4 group. The performance declines were correlated with intelligence, but the difference in performance decline between the low T4 group and controls was not related to intelligence. No correlation was found between onset of treatment for CH and sustained attention. A suboptimal motor system may have been a factor underlying the sustained attention deficit in CH children. [1]

COMMENT. Motor, cognitive, and motivational factors may influence scores on continuous performance tasks. All three factors can be important influences on sustained attention in children with congenital hypothyroidism.

Pituitary enlargement on MRI in congenital hypothyroidism, mimicking a sellar or suprasellar tumor, is reported from the Bai Jerbai Wadia Hospital for Children and Institute of Child Health and Research Centre, Parel, Bombay 400 012, India [2]. The CH was long-standing and untreated. MRI was abnormal in all patients. One child presented with acute headache, vomiting, and papilledema. MRI showed pituitary enlargement, suggesting a pituitary adenoma. Bone age was retarded. Symptoms improved within 10 days of levothyroxine therapy, and an MRI at 2 months showed marked regression of pituitary size. Serum triiodothyronine and thyroxine levels were low, and thyrotropin was elevated in all patients. Prolactin was elevated in 5 patients and was highest in the child with neurologic symptoms. This complication of congenital hypothyroidism will be encountered primarily in developing countries and is rare in the US, since most patients will have received treatment soon after birth. However, an awareness of pituitary enlargement as a sign of CH will avoid unnecessary neurosurgical intervention in children with untreated or subtle hypothyroidism.