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At a glance

A lethal form of chondrodysplasia characterized by rhizomelic limb shortening and giant cell chondrodysplasia.

Synonyms

Atelosteogenesis Type I; Spondylohumerofemoral Hypoplasia.

Incidence

Unknown. Approximately 12 cases have been described.

Genetic inheritance

Autosomal dominant transmission. The genetic defect is caused by mutations in the FLNB (Filamin B) gene that has been mapped to chromosome 3p14.3.

Diagnosis

The diagnosis is made based on the clinical and radiological findings of micromelic dwarfism (distal hypoplasia of the humeri and femora), and hypoplasia of the midthoracic spine. Histological examination reveals multiple degenerated chondrocytes that are encapsulated in fibrous tissue, resting cartilage that appears intact, but hypocellular areas with multinucleated chondrocytes that are interspersed with areas of normal cellularity. Molecular genetic testing for FNLB mutations can be used to confirm the diagnosis.

Clinical aspects

All reported cases were stillborn or died soon after birth secondary to respiratory failure. Head and neck anomalies may include facial hemangiomas, frontal bossing, prominent globes, edematous eyelids, depressed nasal bridge, nose and midface hypoplasia, micrognathia, cleft palate, and short neck. Airway and pulmonary anomalies may consist of laryngeal and tracheal stenosis, small tunnel chest, missing ribs, and pulmonary hypoplasia. Limb anomalies may include distal humeral and femoral hypoplasia, knee/elbow subluxations, talipes equinovarus, hypoplastic/absent fibulae, bowed radius/fibulae, and phalangeal mineralization defects. Anomalies of the axial skeleton may present as cervical vertebral fusion, midthoracic spine hypoplasia with platyspondyly, and sagittal and coronal clefting. Encephaloceles have been reported.

Precautions before anesthesia

Anesthesia in this condition has not been described and it seems very unlikely that these patients present for anesthesia, but anesthesiologists could get involved in resuscitation attempts in one of these children at birth. Check for signs of difficult airway and assess neck mobility.

Anesthetic considerations

Cervical vertebral fusion and the facial features make airway management potentially difficult, thus maintenance of spontaneous ventilation is recommended until the airway has been secured. Alternative airway management options should be immediately available (eg, supraglottic airway device, fiberoptic bronchoscope) and adherence to an established difficult airway algorithm is advised. A surgeon familiar with surgical airway management and the necessary equipment should easily be available in the operating room. Alternatively, an awake fiberoptic intubation should be considered. The presence of laryngeal stenosis suggests that a smaller endotracheal tube may be required. Small chest and lungs may require smaller tidal volumes and higher respiration rate to avoid baro- and/or volutrauma to the lungs. Vascular access may be difficult due to limb anomalies. Positioning may be challenging.

Pharmacological implications

None specific to this disorder.

Other conditions to be considered

  • Diastrophic Dysplasia (Diastrophic Dwarfism; Diastrophic Nanism Syndrome): Autosomal ...

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