9 April 2003

Dear Editor,

Diaphragmatic paresis or paralysis is not an uncommon problem in newborn infants. In infants with respiratory distress, abnormalities of the diaphragm should be considered after exclusion of common causes. We report on an infant with congenital myotonic dystrophy, who presented initially with respiratory distress due to diaphragmatic paresis detected by real-time two-dimensional ultrasonography.

A male infant was born at 39-week gestation to a 29-year-old Chinese woman with thalassaemia trait and of gravida 2 para 1. Her marriage was non-consanguineous. Both her first pregnancy and her first child were normal. This second pregnancy was uneventful, apart from the presence of polyhydramnios during the third trimester.

The infant, weighing 3720 g, was born by spontaneous vaginal delivery with Apgar scores of 8 and 9 at 1 and 5 min, respectively. Shortly after birth, he developed progressively severe respiratory distress requiring endotracheal intubation and ventilatory support at 2 h of age. He was subsequently transferred to our hospital where he continued to require conventional ventilatory support (Babylog 8000 plus; Drager, Lubeck, Germany) to maintain oxygenation and relief of respiratory distress. Apart from a right-sided undescended testis, no other abnormality was detected clinically. His chest X-ray performed on admission showed an elevated right hemi-diaphragm and a dome-shaped left hemi-diaphragm. Real-time ultrasonography (Apogeee 800 plus; ATL, Bothell, USA) showed marked decrease in movement of his right hemi-diaphragm when compared with his left. His cranial ultrasonograph showed presence of a left-sided subependymal haemorrhage and bilateral periventricular echodensity. His echocardiograph revealed a normal cardiac anatomy and ejection fraction.

He was commenced on intravenous aminophylline. He was extubated after 7 days of ventilation, and was given oxygen via a headbox. However, he developed increasingly marked respiratory distress and hypoxemia requiring re-ventilation using the same conventional ventilator. A repeat abdominal ultrasonography revealed minimal movement of both his hemi-diaphragms, with his left moving slightly more than his right. As the conventional ventilator failed to maintain his lung inflation adequately, he was commenced on high frequency oscillatory ventilation (HFOV) (Model 3100 A, SensorMedics Corp., Yorba Linda, CA, USA) with moderate settings: a mean airway pressure (MAP) of 12 cm H2O, a frequency of 10 Hz, a delta p of 47 and an inspiratory/expiratory ratio of 33%. With these ventilator settings, a repeat chest X-ray showed hyperinflation of his lungs. The MAP of the HFOV was subsequently weaned serially until a level of 6.5 cm H2O, when optimal lung inflation (based on the criteria of maintaining the position of his right hemi-diaphragm at the level of 8½ ribs posteriorly) was achieved. He required HFOV at this level of MAP for 28 days before he could be weaned to nasal continuous positive airway pressure (CPAP). He tolerated nasal CPAP therapy well and was weaned from this support after 2 weeks.

During the course of ventilatory support, he remained active with good muscle tone and power. However, he gradually developed a tented mouth, bilateral inguinal hernia and poor sucking reflex. He also continued to have mild respiratory distress (as indicated by mild subcostal recession) after being weaned from nasal CPAP. After 6 weeks of hospitalization, he was finally discharged home.

Prior to discharge, a repeat real-time abdominal ultrasonography revealed persistence of poor movement of both his hemi-diaphragms. At 2 months of age, a brain magnetic resonance imaging scan showed features suggestive of cerebral atrophy. Laboratory investigations showed no evidence suggestive of congenital infection, inborn error of metabolism and chromosomal disorders. His nerve conduction study, electromyograph (EMG) and electroencephalograph were normal. When his mother was examined clinically, she did not show any signs of myotonia. However, the EMG of her first dorsal interosseus muscle showed presence of typical ‘dive-bomber’ discharges upon insertion of the EMG needle; this led us to make the diagnosis of congenital myotonic dystrophy in this infant.

Review of the literature, via Medline between 1966 to August 2002, showed that only one previous report has been published on infants with congenital myotonic dystrophy presenting with respiratory distress due to diaphragmatic paresis or paralysis1. Ghizzi et al. reported a newborn infant who presented with features of hypotonia, diaphragmatic paralysis, facial diplegia and arthrogryposis. Experience from our case suggests that in infants with persistent respiratory distress, particularly those with normal lung findings, a real-time ultrasonography of the diaphragm should be carried out to rule out abnormality of its structure or movement. Occasionally, a chest X-ray, carried out during the expiratory phase, may not reveal elevation of a paralysed hemi-diaphragm(s) with resultant misdiagnosis. Various imaging methods, such as fluoroscopy, computed tomography and radionuclide scanning, have been employed previously to confirm the presence of diaphragmatic paresis/paralysis in the presence of an elevated hemidiaphragm on chest X-ray2,3. However, there are several disadvantages associated with these other techniques.

Shkolnik et al.4 first described the application of real-time sector ultrasonography for evaluation of diaphragmatic motion. The advantages of using the real-time ultrasonography were that the patients did not have to be moved to the radiology department and serial scans could be done and recorded easily for comparison. We therefore, recommend that real-time ultrasonography, which is available in most neonatal intensive care units, could be used as the first-line imaging modality whenever abnormality of diaphragmatic motion or structure is suspected. This can then assist the clinician to investigate further to make the final diagnosis as in our case.


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  2. References
  • 1
    Ghizzi C, Cavallini C, Benedetti M, Bolognani M, Biban P. A  neonatal case of congenital myotonic dystrophy [in Italian]. Acta Bio-Medica Ateno Parmense 2000; 71 (Suppl. 1): 75963.
  • 2
    Merten DF, Bowie JD, Kirks DR. Anteromedial diaphragmatic defects in infancy. Current approaches to diagnostic imaging. Radiology 1982; 142: 361.
  • 3
    Ambler R, Grueneweld S, John E. Ultrasound monitoring of diaphragm activity in bilateral diaphragmatic paralysis. Arch. Dis. Child. 1985; 60: 1702.
  • 4
    Shkolnik A, Foley MJ, Riggs TW et al. New application of real-time ultrasound in paediatrics. Radiographics 1982; 2: 422.