Does a small posterior fossa increase nerve vascular conflict in trigeminal neuralgia?

Background: Magnetic resonance imaging (MRI) can be helpful in visualizing neurovascular conflict (NVC) of the trigeminal nerve in patients with trigeminal neuralgia (TN), but the relationship between these two events is controversial. Purpose: To investigate whether posterior fossa volume is a predisposing factor for NVC in TN. Material and Methods: We conducted a case-control study of clinically diagnosed idiopathic TN of 30 patients aged 30-79 years and 30 age-and sex-matched controls. We compared the volume of the posterior fossa and subarachnoid space using fast-imaging employing steady-state acquisition MRI and the iPlan (R) programme of BrainLab. Results: The posterior fossa volumes in controls and patients with TN were 168.97 cm(3) and 167.63 cm(3), respectively. A small pontomesencephalic cistern volume was more frequent in TN. However, neither the cisternal nor parenchymal portions of the posterior fossa were different between patients with TN and controls, and no significant volume difference was observed in this study. Conclusion: Although the hypothesis that small posterior fossa volume influences TN was feasible, we did not find any volumetric differences (including the cisternal and parenchymal volumes). However, small pontomesencephalic cistern volumes were more frequent in patients with TN.