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M. Turell, S. C. Morrison, E. I. Traboulsi; Comparison of Intrinsic Skeletal Dysplasias Occurring With Cone-Rod Dystrophy. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3730.
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Intrinsic skeletal dysplasias can present concomitantly with ophthalmic abnormalities. In particular, one form of spondylometaphyseal dysplasia (SMD) has been associated with cone-rod dystrophy (CRD) leading to progressive visual impairment. The purpose of this study is to facilitate recognition of SMD-CRD and to differentiate it from other intrinsic skeletal dysplasias occurring with CRD.
A retrospective chart review was performed for a series of patients with intrinsic skeletal dysplasia occuring with CRD. Progression of visual acuity, ophthalmic examination including fundus photography, electroretinography (ERG) data, and sequential radiographic imaging were compared.
In patients with SMD-CRD skeletal abnormalities developed before age 1. Visual symptoms were apparent by age 2. An intermittent fine nystagmus was frequently observed. Fundus examination in SMD-CRD patients generally demonstrated clinically apparent retinal pigment epithelial changes in the macula that were present in early childhood. In two of the SMD-CRD patients, dilated fundus examination revealed similar bilateral well circumscribed chorioretinal atrophy in the macula measuring 3 disc diameters. In these patients, ERG showed reduction in the photopic response and depressed A and B wave amplitudes under scotopic conditions, consistent with CRD. In contrast to other forms of intrinsic skeletal dysplasia with CRD, the major radiographic findings in SMD-CRD included abnormalities of the spine, long bone metaphyses, and bony pelvis that were present by 9 months. There was severe shortening of the long bones. Thoracic and lumbar vertebral bodies had a characteristic ovoid shape. Metaphyses were irregular with prominent bony spurs in the distal ulna and proximal humerus. Severe metaphyseal cupping was identified in the distal ulna and radius. The bony pelvis showed a square-shaped ilium, a narrow sacrosciatic notch, and a shallow acetabulum. These findings in combination with the ophthalmic features are specific for the diagnosis of SMD-CRD.
SMD-CRD is a rare entity distinct from other forms of skeletal dysplasia with CRD. Early identification can aid in management and visual prognosis. Key distinguishing features include: short stature from early childhood with severe shortening of the long bones and bowing of the legs, ovoid vertebral bodies, metaphyseal irregularity with prominent bony spurs and cupping, and early visual impairment with evidence of CRD.
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