Cerebellomedullary compression in recessive craniometaphyseal dysplasia.

Craniometaphyseal dysplasia (CMD) is a very rare disorder of bone remodelling characterised by sclerosis of the skull base, vault and facial bones and metaphyseal splaying of tubular bones. The recessive form appears to be more severe than the dominant. Cranial nerve deficits have been reported in infancy and early childhood in a few patients, but the long-term history of recessive CMD is not well documented. We report cerebellomedullary compression in a girl with recessive CMD recognised at 14 years because of progressive truncal ataxia. MRI revealed backward angulation of the thickened clivus, narrowing of the foramen magnum and upward deviation of the cerebellum by a markedly thickened occipital squama, tonsillar herniation and obliteration of the infratentorial cerebrospinal fluid spaces. Posterior cranial fossa decompression resulted in marked improvement of the ataxia. Compression of posterior cranial fossa structures has to be considered in the natural history and management of CMD.