A 5-month-old boy is brought to the clinic by his parents for a routine follow-up. He was last seen at his well-child check at age 2 months. The patient continues to breastfeed well and recently began eating rice cereal. He can push up from prone position and roll from front to back. He has begun babbling and reaching for objects. The patient was born at term without complications. Vital signs are normal. Anterior fontanelle is open, soft, and flat. The head appears small relative to body size. The patient maintains head control while held on the mother's shoulder. Eyes and ears are in normal position. The palate is intact, and the neck is supple. Cardiopulmonary examination is normal. The abdomen is soft, and there is no organomegaly. Skin examination is unremarkable. Growth charts are shown in the exhibits. Which of the following is the best next step in management of this patient?

Question

A 5-month-old boy is brought to the clinic by his parents for a routine follow-up.  He was last seen at his well-child check at age 2 months.  The patient continues to breastfeed well and recently began eating rice cereal.  He can push up from prone position and roll from front to back.  He has begun babbling and reaching for objects.  The patient was born at term without complications.  Vital signs are normal.  Anterior fontanelle is open, soft, and flat.  The head appears small relative to body size.  The patient maintains head control while held on the mother's shoulder.  Eyes and ears are in normal position.  The palate is intact, and the neck is supple.  Cardiopulmonary examination is normal.  The abdomen is soft, and there is no organomegaly.  Skin examination is unremarkable.  Growth charts are shown in the exhibits.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d6f7_be92_bc81_990371aac734_MD0003_00 Microcephaly is defined as a head circumference measurement >2 standard deviations below the mean, or <2nd percentile for age. Microcephaly may signify an underlying genetic syndrome or perinatal brain insult (eg, infection) but is benign in many cases. For example, benign familial microcephaly refers to a genetically small head circumference that typically occurs in an infant who has normal height and weight and has a parent with a similarly small head. Findings that are suggestive of benign microcephaly include: Absence of syndromic features Normal development Mildly restricted head circumference This 5-month-old patient with mild microcephaly is developing appropriately (ie, babbling, rolling) and has no dysmorphic features on examination. His appropriately open fontanelle is also reassuring because early closure with microcephaly may be associated with an underlying genetic disorder. The next step in management is to measure parental head circumferences. An infant's head circumference that falls within the expected range based on parental head size is consistent with the diagnosis of familial microcephaly, and no further workup is required. (Choice A) Although microcephaly can be caused by congenital infections (eg, cytomegalovirus), symmetric growth restriction (ie, low birth weight, short stature) would typically be expected. Symptomatic infection is also usually associated with other systemic manifestations, such as developmental delay or hepatosplenomegaly. Moreover, parental head circumference measurements should precede more invasive evaluation because this patient may have a normal head size compared to his parents. (Choice C) Genetic testing is performed in patients with microcephaly who have dysmorphic features (eg, low-set ears, up-slanting palpebral fissures) concerning for an underlying genetic syndrome (eg, trisomy 21). This patient has no abnormal facial features. (Choice D) Congenital hypothyroidism (not microcephaly) is associated with a large anterior fontanelle in addition to lethargy, poor feeding, and hypotonia, none of which are seen in this patient. (Choice E) Developmental delay in addition to microcephaly warrants head imaging (eg, ultrasound, MRI) to evaluate for an associated brain malformation (eg, lissencephaly). This patient's development is appropriate for age. Educational objective: Microcephaly refers to head circumference >2 standard deviations below the mean (ie, <2nd percentile). In a child with normal development and an otherwise normal examination, the next step is to measure parental head circumferences to assess for benign familial microcephaly. References: Measuring head circumference: update on infant microcephaly. (http://www.ncbi.nlm.nih.gov/pubmed/26505062)

A 5-Month-Old Boy Is Brought to the Clinic by His