COMMENTARY |
Relationship Between Wilson-Mikity Syndrome and the New Bronchopulmonary Dysplasia
Department of Pediatrics
Keck School of Medicine
University of Southern California
Los Angeles, CA 90033
Abbreviations: WMS, Wilson-Mikity syndrome • BPD, bronchopulmonary dysplasia
In 1960, Wilson and Mikity1 published a report of 5 cases of a new form of respiratory disease in the premature infant. An additional 29 cases were reported from our center in 1969.2 In the intervening years, similar cases had been reported from other centers in the United States, England, Canada, Australia, Switzerland, Italy, and Nigeria, indicating that these cases composed a definite clinical entity of wide geographic distribution. In the early 1960s, none of these infants had received assisted ventilation. Ventilatory support for premature infants became the standard of treatment in the late 1960s. The Wilson-Mikity syndrome (WMS) was swallowed up by bronchopulmonary dysplasia (BPD), the chronic effects of artificial ventilation first reported by Northway et al.3 These were a result of damage to the lung resulting in fibrosis, inflammation, and metaplasia.
The reported infants of WMS all were premature with a medium weight of 1280 g.1,2 The smallest was 830 g, and 26 of the 35 were <1500 g. Only 1 infant weighed >2000 g. Remember, this was from a period when infants <1000 g were considered nonviable and rarely survived. Severity of the illness correlated inversely with maturity. None of the infants was treated with assisted ventilation. None of the infants received >40% oxygen, and most were given oxygen for resuscitation only until after the onset of chronic symptoms. Radiographs in the first week were normal except for 3 infants who had typical respiratory distress syndrome from which they recovered before the onset of chronic symptoms. These early symptoms, which frequently were intermittent, appeared after the first week and consisted of cyanosis, tachypnea, and retractions. Chest radiographs during this stage showed well-expanded lungs with generalized cystic changes. The symptoms increased in severity over the space of several weeks. Twelve infants died in this stage. In those who recovered, the signs and symptoms slowly decreased over the next weeks to months. Radiographs at this time showed basilar hyperaeration and strand-like infiltrate in the upper lobes.
Eleven biopsies were performed, and each of the 12 infants who died was autopsied. Early biopsies (20 days) showed an immature pattern with thick, cellular alveolar septa. Late specimens showed hyperaeration with reduced alveolar septa. Only 1 case had fibrosis, and evidence of inflammation was minimal. The cause of the syndrome was considered to be an abnormal air distribution with a disturbance in ventilation/perfusion secondary to characteristics of the premature lung. Lung histology has been reported by Coalson et al4 in extremely premature baboons that were killed after 71 days of carefully controlled assisted ventilation and oxygen administration. The enlarged air spaces surrounded by thin saccular/alveolar walls with only a few secondary crests was similar to that seen in the late stage of WMS.
Although WMS essentially disappeared from discussions of chronic respiratory problems, there are indications that it was still present. For example, in a study of O2 consumption in 8 infants with the diagnosis of BPD done by Weinstein and Oh5 in 1981, 2 of the infants had not received assisted ventilation. In a more recent study, Charafeddine et al6 classified BPD as typical and atypical depending on the timing of assisted ventilation. In infants 
1250 g birth weight, 31% were classified as atypical. These formed 2 groups: 1) infants whose first symptoms occurred after the first week and 2) infants who had recovered from respirator distress syndrome and were symptom-free for at least 72 hours before the onset of chronic respiratory symptoms. They referenced Wilson and Mikity’s report but did not attribute these cases to WMS, although the description is typical. In the report of the National Institute of Child Health and Development Workshop on BPD held in June 2000, Jobe and Bancalari7 referred to the change in the pathology of the lungs seen in BPD as smaller, and more immature infants have come to constitute the majority of infants who die of BPD. The most recent references in the January 2003 issue of the Journal of Perinatology8,9 are case reports involving infants with WMS. The new BPD, described by Jobe10 in 1999 as occurring in immature infants who do not have much lung disease soon after birth, fits the clinical picture of WMS. Jobe attributes the new BPD to an aberration of lung development, an inhibition of alveolar and vascular development. I believe that the new BPD and WMS are one and the same. As improvements have taken place in the care of women in preterm labor, in surfactant administration and assisted ventilation, classical BPD, a result of injury to the immature lung, has become less common. Chronic lung disease in the premature infant is increasingly likely to be attributable to the response of the immature lung to early air breathing rather than damage from barotrauma or oxygen toxicity. Separating the classification of BPD by cause is important in improving our understanding of the mechanisms involved and the development of potential remedies. The "new" BPD is not so new, having been reported in the 1960s as WMS. The intriguing question that remains is why WMS appears in some infants but not others of presumably the same maturity at birth.
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FOOTNOTES |
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Received for publication Apr 21, 2003; Accepted Apr 21, 2003.
Address correspondence to Joan E. Hodgman, MD, Women’s and Children’s Hospital, 1240 N Mission Rd, Los Angeles, CA 90033. E-mail: hodgman{at}usc.edu
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REFERENCES |
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 TOP REFERENCES |
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- Wilson MG, Mikity VG. A new form of respiratory disease in premature infants. J Dis Child.1969; 99 :489 –499
- Hodgman JE, Mikity VG, Tatter D, Cleland RS. Chronic respiratory distress in the premature infant: Wilson-Mikity syndrome.
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[Free Full Text] - Takama T, Kumada A, Takei Y, Miya T, Zhoshika A. A case of Wilson-Mikity syndrome with high serum KL-6 levels. J Perinatol.2003; 23 :56 –58[CrossRef][Medline]
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- Jobe AH. The new BPD: an arrest of lung development. Pediatr Res.1999; 66 :641 –643
PEDIATRICS (ISSN 1098-4275). ©2003 by the American Academy of Pediatrics
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