By Roberta Friedman, PhD

SAN FRANCISCO (Reuters Health) Oct 25 - Tests to uncover genetic problems and imaging by MRI instead of CT are among the strategies advised in a new set of guidelines for evaluating children with global developmental delay, pediatric neurologists reported here Thursday at a briefing for medical and science writers.

A specific etiology can be determined in the majority of children with global developmental delay, said Dr. Stephen Ashwal of the department of pediatrics at Loma Linda University Medical School in Loma Linda, California. Dr. Ashwal is a co-author of the guidelines.

Insurers and even parents may refuse to pay for the testing costs, which can mount to several thousand dollars, Dr. Ashwal said, even though parents want to know specifically what is wrong with their child.

The report of the quality standards subcommittee of the American Academy of Neurology and the practice committee of the Child Neurology Society contains a decision tree for tests aimed at unraveling causes of delayed development, based on evidence published in clinical studies and reviewed by the committees. The guidelines will be published in the journal Neurology.

Global developmental delay is defined as deficits in at least two of four domains: speech, cognition, social, and self-care. Most doctors, including neurologists, do not carry out the detailed battery of testing that the new guidelines now recommend for diagnosis, Dr. Ashwal said.

The new recommendations call for routine cytogenetic and molecular testing, such as for the Fragile X syndrome. The decision on which tests to perform are based on what clinicians find on examination.

The steps are to obtain a detailed history, refer for auditory and visual screening "no matter what the etiology," Dr. Ashwal said, and consider metabolic studies only if no neonatal screening was carried out.

An EEG should be obtained if seizures are suspected. "MRI should be obtained in preference to CT," Dr. Ashwal said. MRI yield is higher, especially if abnormalities, particularly dysmorphic features, are evident on the physical exam.

If no explanation for the developmental delay can be found in the family history, testing should look for subtelomeric chromosomal rearrangements. Rett syndrome should be considered for girls with unexplained developmental delay.

"You use your expertise to decide which testing is indicated," Dr. Ashwal said.

Even though treatment is not yet available for most cases of global developmental delay, Dr. Ashwal pointed out that new diagnoses and new treatments may become available in the future. "I think all of us who take care of children with these neurologic disorders" have seen a new definition suddenly fit existing patients, he commented.

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