Optic Nerve Hypoplasia With Pituitary Anomaly on MRI Correlates With Hypopituitarism

Kathleen Louden

October 27, 2010

October 27, 2010 (Chicago, Illinois) — A pituitary anomaly on magnetic resonance imaging (MRI) can predict which children with optic nerve hypoplasia (ONH) also have hypopituitarism, an endocrine disorder that can be fatal if untreated, researchers say. The study was presented here as a scientific poster at the American Academy of Ophthalmology and Middle East Africa Council of Ophthalmology 2010 Joint Meeting.

Finding an ectopic posterior pituitary anomaly is highly sensitive and specific for the diagnosis of hypopituitarism in children with ONH, the presenting author, Paul Phillips, MD, told Medscape Medical News. He is a pediatric neuro-ophthalmologist at the University of Arkansas for Medical Sciences Medical Center, in Little Rock.

Diagnosis Can Be Life-Saving

"It gives the ophthalmologist a chance to save a life," Dr. Phillips said in an interview, regarding the correlation between pituitary dysfunction and abnormal neuroimaging.

ONH is a common congenital abnormality. Although many children with the condition have hypopituitarism, Dr. Phillips said it can be difficult to detect. Untreated corticotropin deficiency can lead to cardiovascular collapse. Past studies have had conflicting results on whether radiographic evidence of midline brain abnormalities affects the risk for hypopituitarism.

To determine the reliability of pituitary abnormalities on MRI as an indicator of hypopituitarism, Dr. Phillips and colleagues conducted a retrospective analysis of 41 children with OHN. Thirty-seven patients underwent both a thorough endocrine evaluation and MRI of the brain and sella turcica, which contains the pituitary gland. A masked radiologist interpreted the MRIs.

Fifteen of the 37 children received a diagnosis of hypopituitarism based on endocrinologic evaluation, according to the poster. Of those patients, 14 had ectopic posterior pituitary on their MRI — a 93% sensitivity. Of the 22 patients who had normal pituitary function, 20 had normal MRI findings — a specificity of 91% — the authors' data showed.

"It separated the groups very well," Dr. Phillips said of the pituitary anomaly on MRI, "but it wasn't perfect."

He told Medscape Medical News that 1 of 15 children did not have an anomaly detectable by MRI because "structure does not always correlate with function."

Test Helps Find Children Needing Referral

The study findings are "very helpful," said Hugh Sauer, MD, a pediatric ophthalmologist in private practice in Poughkeepsie, New York. In an interview, Dr. Sauer, who did not participate in the study, said the study better correlates a known association between ONH and midline brain abnormalities.

"The study shows a very high correlation between what you see on the MRI and a pituitary abnormality. It's very predictive," Dr. Sauer told Medscape Medical News. "If the pituitary is abnormal on MRI, you can be almost sure that the hormones will be abnormal, and the patient will need referral for endocrine evaluation."

Another advantage, he said, is that MRI is part of the normal workup for OHN.

However, Dr. Phillips said their findings do not mean that MRI should be the sole diagnostic test in these children. A full diagnostic workup is still necessary, he stated.

Dr. Phillips and Dr. Sauer have disclosed no relevant financial relationships.

American Academy of Ophthalmology and Middle East Africa Council of Ophthalmology 2010 Joint Meeting: Abstract PO469. Presented October 18, 2010.

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