Omodysplasia

Very rare rhizomelic dwarfism disorder characterized by short humeri, hypoplastic everted humeral condyle, proximal radioulnar diastasis, anterolateral radial head dislocation, depressed nasal bridge, broad base of nose, and long philtrum.

Recessive Form: Autosomal recessive omodysplasia; generalized omodysplasia.

Dominant Form: Omodysplasia.

First described in three cases by P. Maroteaux in 1989. Etymologically omodysplasia is defined as shoulder (omo- Greek for shoulder) dysplasia.

Fewer than 30 cases described until 2004.

Autosomal recessive. Many patients are of Hungarian Gypsy origin. Autosomal dominant form affects only the upper limbs.

Pathologic characteristics of this medical condition are the presence of omodysplastic diaphyseal plates showing an expanded zone of proliferating cartilage and an increased number of closely packed small chondrocytes. A functional deficiency of diaphyseal cells is partially replaced by a large number of small chondrocytes in the proliferating zone of the diaphyseal plate. However, the replacement is considered inefficient and leads to weakness of the bone structure. Possible male predominance.

Clinical appearance and bone radiographs show short humeri, radioulnar diastasis at the elbows, short radii and ulnae, short femora with club-shaped upper end. In some cases, a long bone may be missing.

Dwarfism with short limbs and dysmorphic features: flat face with prominent forehead; large tongue; short, upturned nose; brachycephaly; small mandible; large, low-set ears; short neck. Mental retardation and congenital heart disease (patent ductus arteriosus, atrial septal defect, coarctation of aorta, mitral valve prolapse) may be associated. Midline hemangiomas are often present in infants.

Check for congenital heart disease (echocardiography), atlantoaxial joint instability, and presence of sleep apnea syndrome (night oximetry) as for any form of dwarfism. Stenosis of the spinal canal can produce paraparesis, and scoliosis with pectus carinatum can cause restrictive lung disease.

Direct laryngoscopy and tracheal intubation can be difficult because of the presence of macroglossia, micrognathia, and short neck; a laryngeal mask airway and equipment for difficult intubation should be ready for use (e.g., fiberoptic, Bullard laryngoscope, retrograde technique). In case of sleep apnea syndrome, use of a nasopharyngeal airway is recommended during the first hours (and night) after general anesthesia. In case of C1-C2 subluxation, the neck should be stabilized during intubation and positioning of the patient. Special attention to the cervical spine during positioning. Confirm the absence of spinal cord compression before induction of anesthesia or consider somatosensory evoked potentials intraoperatively.

No specific implications.

Robinow Syndrome: Extremely rare autosomal dominant disorder characterized by mild-to-moderate short stature (postnatal growth retardation) and distinctive craniofacial anomalies resembling those of an 8-week-old fetus, called the “fetal face.” Other features include macrocephaly with frontal bossing, ocular hypertelorism (abnormally prominent), anteverted nose, and sunken nasal bridge. May include forearm brachymelia, abnormally short fingers and toes, clinodactyly, unusually small hands with broad thumbs, scoliosis, and thoracic hemivertebrae.