Genetic disorder with unfavorable prognosis manifesting as blindness, mental retardation, and characteristic skeletal changes.
The exact incidence remains unknown. Approximately 15 cases have been reported.
Both autosomal recessive (common) and X-linked recessive transmission (rare) have been reported. Parental consanguinity is considered a risk factor.
Dysplasia of the bone with areas of thickening and areas of sclerosis is responsible for this very distinctive osseous disease. However, the underlying mechanism is unknown.
Made by clinical course and findings of the disorder in combination with the typical radiologic features.
Most typical radiologic finding is platyspondyly (flattening of the vertebral bodies), especially of the thoracic spine with irregular endplates and wide intervertebral spaces. As in osteopetrosis, vertebral bodies and the ribs show a diffusely increased density. Sclerosis is found in the diaphyses and epiphyses of the long bones. The metaphyses are splayed and osteoporotic as a result of cortical thinning, particularly in the lower extremities. Metaphyseal widening extends progressively with time. There is an increased risk of fractures even after trivial trauma. Thickening and sclerosis of the skull base result in macrocephaly and impingement of the basal foramina but particularly of the optic nerve canal, causing optic atrophy with severe visual impairment or blindness, which probably is the most important clinical finding. The electroretinogram and visual evoked potentials confirm the gross loss of function of visual pathways. Other radiologic findings include thickening and sclerosis of the clavicles and scapulae and absent pneumatization of the paranasal sinuses and the mastoids. Less commonly, hearing impairment or deafness may occur. Growth hormone levels are abnormally low, resulting in progressive growth retardation. Occasionally, hydrocephalus, hypertelorism, and micrognathia with a high arched palate and excessive drooling are found. Progressive mental retardation with loss of acquired milestones, sometimes associated with seizures, is another important clinical finding. Dental hypoplasia with delayed eruption of the first teeth and failure of the permanent teeth to erupt are frequent findings. The teeth themselves are of diminished quality, fall out prematurely, and show significant cavities. Macular, violet, or dark rose areas of skin atrophy, which are caused by discrete fragmentation and rarefaction of the elastic layer in the middle and deep sections of the dermis, and flattening of the fingernails may occur.
Precautions before anesthesia
Evaluate the degree of micrognathia. If drooling is excessive, consider anticholinergic premedication. Assess the severity and locations of skeletal lesions. If an epidural or spinal anesthesia is planned, consider obtaining radiographs of the spine.
If micrognathia is significant enough to generate any doubt about airway management, consider fiberoptic tracheal intubation while maintaining spontaneous ventilation. Apply the standard measures for management of increased ...