Angiography of the Posterior Fossa.

Oh, Sae Moon; Cha, Hee Joong; Choi, Kil Soo; Sim, Bo Sung

Original Article

Journal of Korean Neurosurgical Society 1976;5(2): 121-134.

Sae Moon Oh, Hee Joong Cha, Kil Soo Choi, Bo Sung Sim

Department of Neurosurgery, Seoul National University, College of Medicine, Seoul, Korea.

ABSTRACT

Our study was designed for two purpose. The first purpose was to evaluate the incidence of the visualization of the identifiable vessels of the posterior fossa on the vertebral angiography and its significance in the diagnosis of the supra and infratentorial lesions. The second purpose is by measuring the position of the important angiographic landmarks of the posterior fossa on the vertebral angiography to obtain their normal value and to investigate the correlation between the change of the position of the landmarks and the supra and infratentorial lesions. 91 cases of vertebral angiogram performed at Seoul National University Hospital from June 1974 to September 1976 were reviewed. The results were as follows: 1. Generally the vessels of the injected site showed better visualization than the vessels of the opposite site on the Towne's projection and the lateral projection showed better visualization than the Towne's projection with respect to each vessel of the injected site. 2. Reflux of contrast media down the contralateral vertebral artery was seen in about 33% of cases. On the lateral projection, posterior inferior cerebellar artery, precentral cerebellar vein and inferior vermian vein showed high incidence of visualization, which were important in the diagnosis of the posterior fossa lesions. On the Towne's projection posterior choroidal artery, posterior pericallosal artery, precentral cerebellar vein, superior vermian vein and anterior pontomesencephalic vein showed very low incidence of visualization. 3. For the better visualization of the vessels of the posterior fossa, injection with constant and high pressure, precise serialogram, subtraction and magnification techniques were needed. 4. On the lateral projection the normal value of the distance between the dorsum sellae the basilar artery was 6.0mm (3.0mm-10.0mm), and the distance between the midpoint of the clivus and the basilar artery was 3.5mm (1.5mm-10.0mm), and the distance between the anterior rim of the Foramen Magnum and the vertebral was 9.5mm (1.0mm-19.0mm). In some cases of craniopharyngioma the tip of the basilar artery was displaced posteriorly and in the most cases of the space occupying lesions of the posterior fossa the basilar artery was displaced anteriorly and compressed to the clivus. 5. On the lateral projection normal value of the distance between the choroidal point and the clivus/IOP line was 9.5mm (1.0mm-19.0mm). Normal value of the projection of the distance between the anterior rim of the Foramen Magnum and the point on the clivus/IOP line crossed by a perpendicular line from the choroidal point to the length of the clivus/IOP line was 39% (28%-49%) and in 78% of cases within the range of 35%-43%. Generally in the most cases of the space occupying lesions of the posterior compartment of the posterior fossa the choroidal point was displaced anteriorly, and in the most cases of the space occupying lesions of the anterior compartment of the posterior fossa the choroidal point was displaced posteriorly, and in the most cases of the supratentorial space occupying lesions the choroidal point showed no change. 6. On the lateral progection distance between the copular point and the clivus/IOP line was 7.5mm (1.0mm-11.5mm). In the most cases of the space occupying lesions of the posterior fossa it was over 11.5mm. 7. On the Towne's view the normal position of the bifurcation point of the basilar artery was 0.3mm left from the midline and its normal range was 3mm left and right from the midline. In the most cases of the cerebellopontine angle tumors and some cases of large cerebellar hemispheric tumors the bifurcation point of the basilar artery was displaced to the opposite of the tumors. 8. On the Towne's projection the maximal width of the ambient segments of the posterior cerebral arteries was 41.0mm (32.0mm-52.0mm) and the minimal width of the quadrigeminal segments of the posterior cerebral arteries was 17.0mm (6.0mm-28.0mm). In the cases of brain stem tumors the widths of the both ambient and quadrigeminal segments were widened, and in the most cases of posterior fossa lesions showing the upward supratentorial herniation and in the all cases of the pineal tumors the width of the quadrigeminal segments of the posterior cerebral artery was widened. 9. On the lateral projection the normal value of the distance between the C-C point and the Twining's line was 11.2mm (5.0mm-17.0mm). The normal value of the proportion of the distance between the tuberculum sellae and the point on the Twining's line was 50%(45%~54%) and in 76% of cases within the range of 49%~51%. In the most cases of the pineal tumors, thalamic tumors and the tumors of the anterior compartment of the posterior fossa the C-C point was displaced posteriorly, and in the cases of the tumor of the posterior compartment of the posterior fossa the C-C point was displaced anteriorly. 10. On the Towne's projection the normal value of the angle between the midline and the line connection the torcular Herophili and the copular point was 11?6?20?. In the most cases of the cerebellopontine angle tumors and some cases of the cerebellar hemispheric tumors the angle was closed, and in some cases of the cerebellar vermis tumors the angle was opened. 11. In the most of the vascular diseases of the posterior fossa the values of the measurements of the anatomical landmarks of the posterior fossa were within normal limit.