Abnormal pituitary points to hypopituitarism in children with ONH

September 1, 2013

Identifying hypopituitarism in children with optic nerve hypoplasia (ONH) is important because they are at risk of impaired growth, hypoglycemia, seizures, brain damage, and death, according to Paul H. Phillips, MD.

 

Little Rock, AR- Identifying hypopituitarism in children with optic nerve hypoplasia (ONH) is important because they are at risk of impaired growth, hypoglycemia, seizures, brain damage, and death, according to Paul H. Phillips, MD.

However, with treatment of the endocrine dysfunction, the risks can be reduced, said Dr. Phillips, professor, Department of Ophthalmology, and chief, Ophthalmology Services, Arkansas Children’s Hospital, Little Rock.

Pituitary abnormalities detected by magnetic resonance imaging (MRI), he said, are sensitive and specific markers of hypopituitarism in children with ONH.

The imaging shows anomalies, such as absence of the septum pellucidum, hypoplasia of the corpus callosum, and migration and pituitary abnormalities. MRI delineates the pituitary anatomy, specifically the pituitary stalk and the posterior pituitary bright spot.

Abnormalities of the pituitary-such as absence of the infundibulum and posterior pituitary ectopia-have been correlated with endocrine dysfunction, Dr. Phillips said.

A retrospective study was conducted to determine the sensitivity and specificity of the structural pituitary abnormalities seen on MRI for detecting hypopituitarism in children with ONH.

There were 125 children analyzed whose ONH been diagnosed with ONH on fundus examination between 2007 and 2012, and had undergone cranial MRI and pediatric endocrinologic evaluation.

The pituitary was considered normal when the infundibulum was present and the posterior pituitary bright spot was in the sella, but the pituitary was abnormal when the infundibulum was absent or the posterior pituitary bright spot was absent or ectopic.

There were 102 patients (54 boys, 48 girls; mean age at presentation, 3 ± 3.5 years) who met the inclusion criteria. Unilateral and bilateral ONH was seen in 25 and 77 patients, respectively.

“Neuroimaging showed an absent posterior pituitary in 12 patients, ectopic posterior pituitary in 14 patients, and an absent or thin infundibulum in 19 patients,” Dr. Phillips said. “Most patients had more than one abnormality.”

Normal endocrine function was found in 75 (74%) patients and abnormal endocrine function was found in 27 (26%) patients, including growth hormone deficiency (n = 20), thyroid-stimulating hormone deficiency (n = 21), adrenocorticotropic hormone deficiency (n = 10), and diabetes insipidus (n = 10).

Among those with hypopituitarism, Dr. Phillips said the MRI revealed pituitary abnormalities in 26 of the 27 patients, for a sensitivity of 96%.

In the patients who had normal endocrine function, the MRI showed normal endocrine function in 69 of 75 patients, for a specificity of 92%, which was highly significant (p = 0.0001).

If the MRI shows an abnormal pituitary, Dr. Phillips said the patients are at risk for hypopituitarism.

“This has been a consistent finding in studies,” he said. “A question remains, however, in patients with a normal pituitary . . . We agree that these patients are still at risk for endocrine dysfunction and require endocrinologic evaluation, however, among our children, these patients are at low risk for endocrine dysfunction.”

 

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