Foramen magnum impaction in a case of acro-osteolysis.

A case of a rare, non-familial, generalized, congenital, osseous dysplasia is described with features which have previously been described under the name 'acro-osteolysis'. Basilar invagination followed defective bone formation in the skull and this produced occipital headache and progressive neurological deterioration with involvement of the lower cranial nerves and cerebellar function. Hydrocephalus and valvular impaction of the cerebellum in the foramen magnum were demonstrated. Partial relief was obtained by foramen magnum decompression; death supervened from infection and respiratory inadequacy at the age of 20.