Discussion:
We present the complex case of a patient with VACTERL association, SMA,
and pulmonary stenosis. Evaluation of the tracheobronchial system should
be considered for all children with VACTERL association who present with
respiratory symptoms. Longer-term complications of TEF can include
tracheomalacia, TEF recurrence, esophageal stricture, and
gastroesophageal reflux disease.9,10 Congenital
tracheal stenosis5 and bronchial
stenosis6 have been reported in two infants with
VACTERL association. There should be a low threshold for investigation
when patients with VACTERL association present with persistent or severe
respiratory symptoms.10 Our patient differed from the
prior cases as he did not require overnight ventilatory support until 2
years of age and did not show overnight desaturation until 7-1/2 years
of age. His clinical presentation was further complicated by his
diagnosis of SMA.
Concomitant neuromuscular diseases can present a challenge when
evaluating respiratory dysfunction. Patients with progressive
neuromuscular disorders demonstrate decline in respiratory status with
time. Ineffective cough, weak accessory muscles leading to nocturnal
hypoventilation, and sleep-disordered breathing are
common.11 Due to imbalance between respiratory muscle
strength and increased respiratory load from scoliosis and chest wall
deformities, patients with neuromuscular disorders are at risk for
respiratory failure.12 Specific diseases can show a
predilection for specific respiratory muscles. Infants and children with
an untreated, severe form of SMA show prominent intercostal muscle
weakness with accompanying paradoxical abdominal
breathing.13 In SMA, diaphragm function appears to be
relatively spared.14 Neuromuscular diseases such as
Duchenne muscular dystrophy show preferential weakness of expiratory
muscles and diaphragm involvement while collagen 6A-related congenital
muscular dystrophies may show a restrictive pattern of respiratory
weakness resulting from more severe diaphragm
weakness.8 Sitting versus supine forced vital capacity
(FVC) testing can be particularly helpful in this
regard.15
Patients with neuromuscular disease are anticipated to have normal lung
parenchyma and airway resistance, at least early in their
presentations.11 The high inspiratory pressure
requirements in our patient to overcome his stenotic airway would not be
expected in neuromuscular respiratory dysfunction. The anatomic lesion
observed also explains the ventilator dysynchrony observed in our
patient. Ultimately, both airway and ventilation issues need to be
considered when complex patients present with respiratory dysfunction.
In patients with underlying genetic syndromes and neuromuscular
conditions, the described specific clinical patterns of respiratory
dysfunction combined with polysomnogram data and imaging findings can
help clarify the etiology of respiratory dysfunction, and guide
management options.