Basilar impression

In cases of basilar impression, CT of the cranium and upper cervical spine can image the invaginated odontoid process and other bony anomalies. A typical CT finding is a complete dense ring of bone on the lower cut of the posterior fossa at which level in normal cases there is still brain tissue (Boles et al. 1977). Moreover, such accompanying anomalies as syrinx, Chiari malformation, hydrocephalus are also detectable (di Chiro and Schellinger 1976, Nakagawa et al. 1977, Lee et al. 1978, Oberson and Azam 1978, Carella et al. 1981, Isu et al. 1983). 

In basilar impression marked angulation of the vertebral artery can to be seen. An abnormal position of the PICA may identify the Chiari malformation. 

Boles, D. M., van Dellen, J. R., Danziger, A., 1977 Computerized tomography findings in a case of basilar impression. Suid-Afr. Tyds. Chir. 15, 241—244. 

McGregor, M., 1948 The significance of certain measurements of the skull in the diagnosis of basilar impression. Brit. J. Radiol. 21, 171—181. 

Pasztor, E., Vajda, J., Piffko, R, Horvath, M., 1980 Transoral surgery in basilar impression. Surg. Neurol. 14, 473—476. 

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