Biophysical bases for delayed and aberrant motor development in young children with achondroplasia.

Achondroplasia, the most common skeletal dysplasia, is characterized by delayed and aberrant motoric development in childhood. Delays and aberrancy are secondary to the anatomical differences inherent in people with achondroplasia. We present a photographic essay documenting biophysical differences, aberrant pre-orthograde movement strategies, and selected adaptive techniques. A parental questionnaire assessed the presence of, predominance, and ages at which various types of pre-orthograde locomotion were observed. Fine and gross motor skills were assessed contemporaneously by use of the Denver Developmental Screening Test in 93 children with achondroplasia and were found to be more delayed than previously reported. Physicians, therapists, early-childhood educators, and parents should recognize that aberrant does not mean maladaptive and that different development is not defective development.

Prevention of fixed, angular kyphosis in achondroplasia.

Transient kyphotic deformity arises in most infants with achondroplasia. In a minority, a fixed and angular kyphosis develops, which can cause serious neurologic sequelae later in life. We assessed a protocol for preventing development of such fixed kyphosis in a sequential, unselected series of 66 infants with achondroplasia. This study demonstrates the efficacy of early prohibition of unsupported sitting and, in those in whom such prohibition proves insufficient, use of bracing. When the proposed algorithm was followed, none of the infants had development of a progressive kyphotic deformity. On this basis, it appears that the secondary risks of angular kyphosis, previously estimated to be between 10 and 15% in individuals with achondroplasia, can be completely eliminated.

Prospective assessment of risks for cervicomedullary-junction compression in infants with achondroplasia.

Achondroplasia, the most common heritable skeletal dysplasia, may result in abnormality at the craniocervical junction, which is a potentially lethal problem in a subset of young infants with this disorder. We evaluated and followed an unbiased and unselected consecutive series of infants with achondroplasia, to better document the occurrence, frequency, and clinical presentation of craniocervical abnormalities. Of 53 prospectively ascertained infants, 5 were judged to have sufficient craniocervical junction compression to require surgical decompression. Intraoperative observation always showed marked abnormality of the cervical spinal cord, and all operated-on children showed marked improvement of neurological function. The most frequent clinical abnormalities within this subset were those expected for high cervical myelopathy. The best predictors of need for suboccipital decompression included lower-limb hyperreflexia or clonus, on examination; central hypopnea demonstrated by polysomnography; and foramen magnum measures below the means for children with achondroplasia. Infants with achondroplasia are at risk for potentially lethal sequelae of craniocervical junction abnormalities; selective intervention can be life and health saving, but individuals at high risk will be identified only if all affected infants undergo comprehensive assessment in infancy.

Further evidence that arthrogryposis multiplex congenita in the human sometimes is caused by an intrauterine vascular accident.

A 7 1/2-year-old girl with arthrogryposis multiplex congenita of the amyoplasia type in association with intestinal atresias, gastroschisis, Möbius anomaly, and hypoplasia of the pectoral, biceps, and deltoid muscles is described. Several combinations of these birth defects have been previously described. There is considerable evidence that gastroschisis, intestinal atresia, Poland sequence, and Möbius anomaly each has a vascular pathogenesis. Based on the associations seen in this child and past reports of more limited, similar cooccurrences, we suggest that arthrogryposis multiplex congenita may sometimes be caused by an intrauterine vascular catastrophe.