Small Posterior Fossa as a Predisposition of Neurovascular Conflict

Introduction: Development of neurovascular conflict has not yet been fully explained. Some authors suspect vessel elongation to be the cause of the conflict, while others discuss the age-dependent brain descend. The authors suspected the relatively small posterior fossa being a predisposing factor for neurovascular conflict development.

Material and Methods: Using x-ray scans of the skull, the size of the posterior fossa was expressed in terms of the quantities X = a/c, Y = b/d from the following measurements: distance between posterior clinoid process (PCP) and internal occipital protuberance (IOP) = a; distance of foramen magnum from the line joining PCP and IOP = b; distance between the anterior edge of frontal sinus and IOP = c; distance between inner diploë and line joining PCP and IOP = d. The series included 50 patients with typical trigeminal neuralgia or facial hemispasm: results X1,Y1. The control group consisted of 50 randomly selected healthy individuals who were skull x-rayed for brain concussion.

Results: Agreement of the corresponding ratios was statistically tested. The results are as follows: T-test for X values: p = 0.017, T-test for Y values: p = 0.004. This shows that indices X and Y are statistically different.

Conclusions: The results confirm that the posterior fossa is significantly smaller in size in the group of patients with neurovascular conflict as compared with controls. In conclusion, constitutionally small posterior fossa may be a predisposing factor for neurovascular conflict development.