Introduction: Trigeminal neuralgia (TN) occurs and recurs in the absence of neurovascular compression (NVC) in a substantial portion of TN patients. While the contribution of NVC to the pathophysiology of TN is still a subject of debate, the cause of TN when there is no NVC is completely unknown. Here we examine neuro-anatomic differences between TN with and without NVC
Methods: A volumetric study was performed on TN patients who had undergone surgical treatment. Measurements were performed using reconstructed images of BFFE sequence magnetic resonance images. We studied 143 patients with TN1 (117 with vascular compression, and 26 without) and 25 patients with TN2 (24 with vascular compression and 1 without). Following measurements were obtained: cerebellopontine angle (CPA) volume, posterior fossa volume, pons volume, length of cisternal portion of trigeminal nerve, and transverse distance between the two porus trigemini. Student t-test was used to compare means between the two groups. The study was IRB-approved. Measurements were performed on OSIRIX.
Results: The posterior fossa volumes in cases of TN with NVC and TN without NVC were ?144.5 ± 18.24 cm3 and 136.174?± 18.23 cm3, respectively (p = 0.028). The CPA volumes were ?1.41 ± 0.98 cm3 and 1.148 ± 0.657 cm3 , respectively (p=0.154). The length of cisternal portion of trigeminal nerve were ?8.38±2.17 cm and 8.77?± 1.39 cm, respectively (p= 0.38). The pons volumes were ?2.49 ± 0.63 cm3 and 2.49 ± 0.18 cm3, respectively (p=0.98). The distance between the two porus trigemini were ?3.26 ± 0.23 cm and 3.29 ± 0.1cm, respectively (p=0.51)
Conclusions: The mean posterior fossa volume in TN patients without NVC is 8.3 cm3 (5.79%) smaller than the posterior fossa volume in TN patients with NVC. Smaller posterior fossa volume could contribute to development of TN. Larger and matched controlled comparisons are needed.
Patient Care: Will help design and provide care to patients with trigeminal neuralgia
Learning Objectives: 1-Understand Pathophysiology of Trigeminal Neuralgia
2-Understand the morphological differences between TN types.