NATURAL HISTORY: CAMPOMELIC DYSPLASIA 4/97
[NOTE:THE FOLLOWING SUMMARY OF THE NATURAL HISTORY OF CAMPOMELIC DYSPLASIA IS NEITHER EXHAUSTIVE NOT CITED. IT IS MEANT TO PROVIDE A GUIDELINE FOR THE KINDS OF PROBLEMS THAT MAY ARISE IN CHILDREN WITH THIS DISORDER, AND PARTICULARLY TO HELP CLINICIANS CARING FOR A RECENTLY DIAGNOSED CHILD. FOR SPECIFIC QUESTIONS OR MORE DETAILED DISCUSSIONS, FEEL FREE TO CONTACT THE MIDWEST REGIONAL BOND DYSPLASIA CLINIC AT THE UNVERSITY OF WISCONSIN – MADISON [ 608-262-9722: FAX – 608-263-3496; EMAIL –
PAULI@WAISMAN.WISC.EDU]
MEDICAL ISSUES AND PARENTAL CONCERNS TO BE ANTICIPATED
PROBLEM: SURVIVAL
EXPECTATIONS: Most Infants with this disorder die, apparently secondary to respiratory insufficiency. Various factors contribute to those risks. (SEE BELOW) Many die in the first days of life, some over the course of the first year. Few of those who survive beyond the first year are free of severe sequelae.
MONITORING: Anticipatory guidance and counseling of the family.
INTERVENTION: In depth discussions with the family are essential, including consideration of generation of Advance Directive, copies of which should be placed at all clinics and hospitals where the infant may be cared for.
PROBLEM: RESPIRATORY PROBLEMS
EXPECTATIONS: Many factors contribute to severe respiratory risks. The chest of often markedly constricted. The airways are diminished in size and there may also be severe laryngotracheobronchomalacia. The mandible is often very small and subsequent retroglossia can cause upper airway obstruction. And there may be abnormalities of central respiratory control (central apnea) because of abnormalities of the cranial base. All may contribute to immediate neonatal risk of death and, in survivors, to long term sequelae.
MONITORING: Evaluation in survivors of the neonatal period should include: polysomnography, bronchoscopy in those with apparent sever airway involvement.
INTERVENTION: May include symptomatic management with oxygen supplementation, use of cpap or bipapa, tracheostomy as needed etc. Surgical chest expansion has not been shown to be of any benefit. Airway infections should be aggressively treated. Prophylactic treatment during RSV epidemics should be considered. Immunizations should be given, including Hemophilus and Influenza (using split dose split virus preparations in infant and vaccination of all household contacts.
PROBLEM: ANESTHESIA RISKS
EXPECTATIONS: Many infants may require surgery. Risks include those related to the airway and the cervical sine.
MONITORING: Cervical spine should be assessed for stability with plain lateral xrays. Flexible bronchoscopy should be done prior to intubagtubation.
INTERVENTION: Weaning and extubation need to be carried out cautiously.
PROBLEM: CENTRAL NERVOUS SYSTEM AND DEVELOPMENT
EXPECTATIONS: May have structural anomalies ( most commonly arhinecephaly). With or without structural aberrations survivors may show serious developmental abnormalities, with profound variability from survivor to survivor. It is not clear what contributes to developmental abnormalities (primary vs. secondary to sequlae of hypoxia etc.)
MONITORING: Periodic formal developmental evaluations throughout infancy and early childhood.
INTERVENTION: Infant stimulation should begin early. Other interventions as indicated by period developmental evaluations.
PROBLEM: CHONDROCRANIUM AND CRANIOCERVICAL JUNCTION
EXPECTATIONS: The skull base is clearly small, but little assessment has been documented. Structure suggests that ther may be risk for craniocervial junction compression with secondary hypotonia and/or abnormalities of central respiratory control. There may also be risk for cervical spine instability.
MONITORING: Survivors should have magnetic resonance imaging of the craniocervical junction. Plain xrays of the cervical spine (flexion, neutral and extension lateral views) should be completed in the first six months and, in general, about every 6-12 months thereafter.
INTERVENTION: If craniocervical compression is documented, consider suboccipital decompressive surgery. If there is severe c-spine instability surgical fusion may also be needed.
PROBLEM: TALIPES EQUINOVARUS
EXPECTATIONS: Clubfoot is virtually constant.
MONITORING:
INTERVENTION: Early initiation of passive range of motion and usual surgical intervention.
PROBLEM: SPINE
EXPECTATIONS: Scoliosis and kyphosis exceedingly common in survivors.
MONITORING: Clinical monitoring at each visit. Thoracolumbar spine xray should be obtained of progressive scoliosis or kyphosis is detected clinically.
INTERVENTION: Usual treatment. Note, however, that bracing may be problematic because of effects of respiration.
PROBLEM: HIP DISLOCATION
EXPECTATIONS: Common
MONITORING: AP and frogleg xrays in infancy.
INTERVENTION: Usual, nonsurgical orthopedic treatment is usually effective.
PROBLEM: RADIAL HEAD DISLOCATION
EXPECTATIONS: Exceedingly common. May result in limited elbow movement.
MONITORING: -
INTERVENTION: No treatment indicated.
PROBLEM: HEARING
EXPECTATIONS: This is an underdocumented but serious concern. Likely arises because of combination of structural aberrations of the internal ear and recurrent middle ear dysfunction, particularly in those wth cleft palate. May be significant contributor to speech and language delays in survivors.
MONITORING: Consider brainstem auditory evoked response testing in infancy. Periodic behavioral testing should begin by around 9 months of age.
INTERVENTION: Amplification (aids) should be fitted if structural basis of hearing loss is demonistrated. Middle ear abnormalities (infection, fluid) should be treated aggressively, including having a low threshold for myringotomy and tube placement.
PROBLEM: CLEFT PALATE
EXPECTATIONS: Present in about 1/3 of infants with this disorder.
MONITORING: -
INTERVENTION: Closure at usual time of general health status allows.
PROBLEM: CARDIOVACSULAR ANOMALIES
EXPECATIONS: Present in about ¼ of infants with this disorder.
MONITORING: Echocardiography and cardiologic assessment in infancy.
INTERVENTION: Usual medical management if anomalies discovered.
PROBLEM: RENAL ANOMALIES
EXPECTATIONS: May have congenital anomalies or acquired problems including secondary to vesicoureteral reflux.
MONITORING: Renal ultrasound in infancy, and probably yearly thereafter in survivors.
INTERVENTION: Usual medical management if problems identified.
PROBLEM: GASTROESOPHAGEAL REFLUS
EXPECTATIONS: Present in many.
MONITORING: By Medical history.
Intervention: May complicate feeding. May increase risk for aspiration in pulmonologically fragile infants.
PROBLEM: SEX REVERSAL
EXPECTATIONS: Many phenotypic females are found to be 46 XY. In females who have 46 XY there is a high risk of gonadoblastoma. Some 46 XY males have structural genital abnormalities.
MONITORING: Chromosomal evaluation.
INTERVENTION: Early gonadectomy in all 46 XY females.
GENETICS AND MOLECULAR BIOLOGY
Recently is has been discovered that Campomelic Dysplasia is caused by variably sized deletions ( or other changes) of the long arm of one chromosome 17. Such deletions either include or affect a locus called SOX9 which is crucial in normal sexual differentiation. Chromosomal assessment of the 17q region should be completed in all affected individuals since those with microscopically demonstrable deletions seem to be less severely affected and may have a better chance for long term survival. The SOX9 product also influences cartilage development and so it is conceivable that all of the phenotypic effects in Campomelic Dysplasia arise secondary ot the effects of haploinsufficiency at this single locus.
Recurrence risk is low, estimated to be 5% or less in subsequent pregnancies of couples who have had one affected child. That risk probably arises because of occasional germinal mosaicism in one or the other parent.