Introduction: Trigeminal neuralgia (TN) occurs and recurs in the absence of neurovascular compression (NVC)1. To further characterize what may be distinct patient populations, we examined the age at onset of patients with trigeminal neuralgia with and without NVC.

Methods: We performed a retrospective study of patients undergoing posterior fossa surgery for Type I TN at Oregon Health and Science University from 2009 to 2013. Chart review, imaging and findings at surgery were used to determine the age of onset in patients with and without NVC. Mean, median, and the empirical cumulative distribution of onset age were determined for each group. Statistical analysis was performed using Student’s T-test, Wilcoxon and Kolmogorov-Smirnoff tests for each measure, respectively.

Results: A total of 156 TN patients were examined. There were 129 patients with NVC and 37 patients without NVC. Mean age of onset of symptoms for patients with NVC was 51.1 years, and 42.6 without NVC. This difference is significant (p=0.007), with sufficient power for an effect size of 8.2 years. Median age between groups is also different (NVC: 53.25; No NVC: 41.2; p=0.003). Histograms show onset age appears bimodal in patients without NVC (Figure 1), and the cumulative distribution of onset age of shows earlier presentation of symptoms (p=0.0029) in patients without NVC (Figure 2). Chi-square analysis reveals a trend toward female predominance in patients without NVC (Figure 3), but this was not statistically significant (p=0.08).

Conclusions: NVC is neither sufficient nor necessary for the development of TN1,2. The data we present here imply that patients without NVC may represent a distinct population of younger patients, who may be predominantly female. These findings highlight the need for further research into the pathophysiology underlying this debilitating disease.

Patient Care: TN patients with and without NVC may represent different subpopulations with the disease; the distinction raises questions regarding the underlying pathophysiology of this disease, and may provide insights into researching treatment options in the future.

Learning Objectives: At the end of this session, attendees should be able to: 1. Describe the differing age characteristics of TN patients with and without NVC. 2. Discuss the implications of these findings vis-a-vis the role of NVC in the pathogenesis of TN.

References: 1. Lee A, McCartney S, Burbidge C, Raslan AM, Burchiel KJ: Trigeminal neuralgia occurs and recurs in the absence of neurovascular compression: Clinical article. J Neurosurg:1–7, 2014 2. Miller JP, Acar F, Hamilton BE, Burchiel KJ: Radiographic evaluation of trigeminal neurovascular compression in patients with and without trigeminal neuralgia: Clinical article. J Neurosurg 110:627–632, 2009