Identification and Evaluation of Mental Retardation

American Family Physician,  Feb 15, 2000  by Donna K. Daily,  Holly H. Ardinger,  Grace E. Holmes

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Information should be obtained about the family unit, parents' occupations and educational achievements, educational and developmental status of siblings, role of the patient in the family, discipline of the children and identity of the child's caregiver when the parents are not home. Family history of fetal loss, mental retardation, severe learning problems, congenital abnormalities and unexplained childhood deaths, as well as other serious illnesses in first- and second-degree family members, should be elicited.

A complete physical examination can begin with a review of growth curves since birth, if these are available. The head circumference should continue to be plotted. The examination should be thorough, with special attention to physical findings that are compatible with any risk factors obtained from the history.

The child should be examined closely for dysmorphic features or minor abnormalities, such as unusual eyebrow pattern, eyes that are widely or closely spaced, low-set ears or abnormal palmar crease patterns. Minor abnormalities are defined as defects that have unusual morphologic features without serious medical implications or untoward cosmetic appearance.8 Most minor abnormalities involve the face, ears, hands or feet, and are readily recognized even on cursory examination.14 The presence of three or more minor abnormalities in newborns is correlated with a 90 percent frequency of coexistent major abnormalities,15 suggesting close association with morphogenesis in utero. Thus, minor abnormalities may provide clues to developmental problems of possible prenatal origin.

Evaluation of the head, face, eyes, ears and mouth must include general assessment of visual acuity and hearing. Examination of the chest, heart, spine, abdomen, genitalia, extremities, muscles and neurologic reflexes can reveal abnormalities that may be associated with retardation. Table 2 highlights five common syndromes or problems associated with retardation.

Evaluation and Referrals

Findings from the history and physical examination of the child will help determine which diagnostic tests and referrals are appropriate for further assessment. The physician needs to explain to the parents what these findings are and the reasons for further evaluation. The laboratory and radiographic assessment of individual children should be based on clinical presentation (Table 3).16

This initial sharing of information with parents is an extremely important step and will probably set the stage for the future physician- family-patient relationship. Ample time should be scheduled to discuss the findings and to allow for questions, which will be numerous. The family should be encouraged to write a list of questions for further communication with the physician. The clinician should clarify the term "developmental delay," because parents frequently misinterpret this as meaning the child has the ability to catch up.

It is best to seek other opinions as soon as mental retardation is suspected rather than adopting a "wait-and-see" approach. The Individuals with Disabilities Education Act (1997)17 provides for developmental assessment of children older than three years in every school district. For children younger than three, similar infant-toddler assessment and early intervention resources are available, usually through local health departments, school districts or regional assessment centers. (The responsible agency varies in each state.)