"Meeting the challenge of rheumatologic diseases in teens" (December 2000) was an excellent article, but I regret that polymyositis was not discussed because this disorder is so often misdiagnosed as muscular dystrophy. Also, muscle biopsy should have been listed among the diagnostic tests for dermatomyositis. (This test should always be performed under local anesthesia by someone who performs muscle biopsy frequently.)
One correction is that creatine phosphokinase (CPK) is not always elevated in patients with dermatomyositis; the level is normal in some cases. Note also that muscle biopsy does not always show inflammation even though an electron photomicrograph may show changes.
The author replies: Dr. Thompson is correct: Polymyositis is part of the differential diagnosis of muscular dystrophy. But the condition is rare in pediatrics and we preferred to focus on illnesses that are more common and that pediatricians are more likely to see.
Muscle biopsy is certainly still helpful in the diagnosis of dermatomyositis, but newer techniques, such as fat-suppressed magnetic resonance imaging (as discussed in the article), give diagnostic information in a noninvasive manner. MRI also allows for periodic monitoring of muscle inflammation, which would be unreasonable using serial biopsy.
It is also true that CPK is not always elevated in dermatomyositiswhich is why the diagnosis is not made on the basis of an elevated CPK level alone but on the basis of additional features, such as presence of the typical rash, symmetric muscle weakness, and elevated levels of aldolase and serum glutamicoxaloacetic transaminase (SGOT). If these features are questionable or the muscle enzyme level is normal, then muscle biopsy with electron microscopy observation and analysis may be helpful and, indeed, necessary for diagnosis.
"Beach week: Sand and swimming or sex and swilling?" (April) is provocative and timely. The article makes the important point that "a teen's conduct during beach week is strongly related to his or her conduct at home." Teenagers' participation in the activities describeddrinking, smoking, illicit drug use, and sexual intercourseis but another example of the breakdown of the parent-child relationship so prevalent in our society. Pediatricians can do little to change that relationship (or teen behaviors) by interviewing the child and parents just before beach week, but they can interview the teen alone, as suggested in the article, and offer help and suggestions.
I applaud the community of Ocean City, Md., for their Play it Safe program. This is the only answer for the poorly parented (or, perhaps, strong-willed) teenager. Last minute parental intervention doesn't work, no matter how well intentioned.
I enjoyed "Emesis and a new murmur in an adolescent: Getting to the heart of the problem" (Pediatric Puzzler, May). It is well written and extremely engaging, and it showcases an excellent case. After reading the article, I was, however, left with several questions: Were viral titers or cultures done, and would they have changed the therapeutic approach? What were the results of the catheterization, and were they helpful in this child's evaluation or in his therapy? Did this adolescent actually have a murmur (it was not mentioned in the physical exam findings)? And, last, while cardiomyopathy is described as a chronic condition, this child's condition seemed very acute. Would his condition be considered acute or chronic?
The author replies: Thanks to Dr. Harkness for his kind words about the Puzzler. He raises important questions about the case, to which we offer the following. First, in regard to viral titers and cultures at the time of initial diagnosis and management, cultures and polymerase chain reaction studies were performed on myocardial biopsy specimens obtained at catheterization, and no virus was isolated. Viral serologic studies were not performed. Had a virus been cultured or otherwise identified, antiviral or immunosuppressive agents might have been used as part of therapy, and this might have delayed potential cardiac transplantation.
Second, the cardiac catheterization demonstrated normal intracardiac anatomy, no evidence of a shunt, elevated right atrial mean pressure, elevated right ventricular end-diastolic pressure, and markedly elevated pulmonary artery and pulmonary wedge pressures. The pulmonary vascular resistance was not elevated. These data were helpful in that they confirmed the need for cardiac transplantation (which occurred not long after diagnosis), and indicated that the degree of pulmonary vascular resistance would not be prohibitive.
Third, as indicated in the Puzzler, the referring pediatrician reported a murmur as part of the child's examination. This was not heard at the subsequent examination, but a gallop was appreciated. Last, this child's condition ought to be considered acute and treated accordingly.
In Table 3 of the Spring 2001 supplement to Contemporary Pediatrics, "Meningococcal infection in adolescents and young adults," the population of freshmen, the third risk group listed, should be 2,285,001.
In "Airbags and children: A mixed blessing" (April), the box "The law and seat belt use" states that use of seat belts in New Hampshire is required only to 12 years of age. This information, obtained from the National Highway Traffic Safety Administration, is in error: In New Hampshire, children younger than 18 years are required to use a seat belt.
In "Demystifying delayed puberty" (April), the calculations for mid-parental height should be:
+ (father's height)
+ (mother's height)