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Updated: Aug 7, 2026
In Vivo Morphometric Analysis of Human Cranial Nerves Using Magnetic Resonance Imaging in Menière's Disease Ears and Normal Hearing Ears
Published on: February 21, 2018
Posterior fossa morphology and cranial nerve configuration in trigeminal neuralgia: A morphometric magnetic resonance
Tomoyuki Naito1, Keisuke Onoda1, Akira Matsuno1
1Department of Neurosurgery, School of Medicine, Narita Hospital, Narita, Chiba, Japan.
Background:
Neurovascular compression is considered the principal cause of trigeminal neuralgia (TN), but vascular contact alone does not fully explain disease occurrence. We hypothesized that posterior fossa morphology and cranial nerve spacing contribute to TN susceptibility.
Methods:
Fifty-six patients were analyzed: 20 with TN, 20 with hemifacial spasm (HFS), and 16 controls. Using three-dimensional magnetic resonance cisternogram/angiogram fusion imaging, five morphometric parameters were defined: (A) frontal-occipital cranial length, (B) posterior fossa depth, (C) anteroposterior diameter of the brainstem between the roof of the fourth ventricle and the ventral pons measured on midsagittal T1-weighted images, (D) distance between the trigeminal and seventh to eighth cranial nerves, and (E) distance between bilateral trigeminal roots. Ratios B/A, D/C, and E/C were calculated.
Results:
The TN and HFS groups had significantly smaller posterior fossa depth indices than controls (TN vs. control, p < 0.01; HFS vs. control, p = 0.007). The interneural spacing index was significantly smaller in TN and HFS (p < 0.001) and further decreased on the affected side in TN (p = 0.041). No significant difference was observed in bilateral trigeminal spacing.
Conclusion:
A compact posterior fossa and reduced cranial nerve spacing may predispose individuals to TN.
