Resumo em Inglês:
The authors outline the development of the spine and skull, particularly of axis, atlas and occipital bone. As neuro-skeletal dysmorphisms, the occipito-cervical malformations belong to the neurodysplastic group. They are classified as skeletal anomalies, associated nervous malformations and meningeal reactions. Vertebralization of the occipital bone and occipitalization of atlas, subluxation of odontoid process, dysplasia of the occipital bone, dystrophia brevicollis and other anomalies are discussed. Special care is given to the study of basilar impression; its concept, history, incidence, clinical and neurological symptoms, radiological characterization (craniographic, perimyelographic and iodoventriculographic aspects) and surgical treatment are reviewed. The authors report five cases of occipito-cervical malformations, which are the first references in Brazilian literature. In case 1 the anomalies (manifestation of occipital vertebra and Arnold-Chiari deformity) were disclosed at an operation for cisticercosis of the posterior fossa. In the following four cases invagination of the basilar portion of the occipital bone (basilar impression) could be radiologically demonstrated; in case 2 a suboccipital craniectomy and a laminectomy of atlas and axis were performed but the patient died a week later and the necroscopic examination confirmed the neuro-skeletal anomalies. In all cases there were several associated malformations. In case 2 there were occipitalization of the atlas, fusion of the first and second cervical vertebrae, supernumerary rib of the seventh cervical vertebra, supernumerary lumbar vertebra, and Arnold-Chiari deformity; at necropsy it was found a syringomyelic cyst on the cervical cord and a fibrous dural ring over the foramen magnum. Case 3 showed the syndrome of Klippel-Feil, besides supernumerary ribs of the seventh cervical and first dorsal vertebrae, Arnold-Chiari malfotmation and probable aplasia of cell groups in the nuclei of oculomotor and facial nerves. In case 4 there were occipitalization of atlas and Chiari deformity. In case 5 vertebral reduction in the cervical region was evidenced but bony coalescence could not be proved. In the last four cases the constitutional morphologic type was determined. Electroencephalograms of cases 3, 4 and 5 showed no abnormalities; in case 1 slow bilateral occipital waves were recorded. The authors call attention to the importance of the diagnosis of these anomalies susceptible of successful surgical correction, which can simulate many nervous diseases of untoward course, like lateral amyotrophic sclerosis, syringomyelia (which can be actually associated to the bony anomaly, as in case 2), sclerosis of dorsal funiculi of the spinal cord, tabes, multiple sclerosis, heredocerebellar ataxia, etc. The authors also stress the clinico-radiological differences between basilar impression and platybasia, frequently taken as synonyms. Although both anomalies may coexist (as in cases 4 and 5) their association is not an absolute rule; on the contrary, in case 2 the basal angle was in the inferior limit of normality and in case 3 it was much lower. Emphasis is put on the value of the Chamberlain's line and chiefly in the McGregor basal line for the correct diagnosis of basilar invagination of the occipital bone.
