Patients with idiopathic trigeminal neuralgia have a sharper-than-normal trigeminal-pontine angle and trigeminal nerve atrophy

Department of Neurosurgery, Bundang CHA Medical Center, CHA University College of Medicine, Seongnam, Kyonggido, Korea, 463-712.
Acta Neurochirurgica (Impact Factor: 1.77). 06/2012; 154(9):1627-33. DOI: 10.1007/s00701-012-1327-z
Source: PubMed


Trigeminal neuralgia (TN) is primarily diagnosed by symptoms and patient history. Magnetic resonance (MR) imaging can be helpful in visualizing the neurovascular compression of the trigeminal nerve in TN patients, but the current parameters used as diagnostic markers for TN are less than optimal. The aim of this study is to assess whether the angle between the trigeminal nerve and the pons (the trigeminal-pontine angle) on the affected side of patients with idiopathic TN differs from that of the unaffected side and that found in controls without TN.
A case-control study of 30 clinically diagnosed idiopathic TN patients aged 30 to 79 years and 30 age- and sex-matched controls was conducted. We compared the trigeminal-pontine angle and trigeminal nerve atrophy via fast-imaging employing steady-state acquisition (FIESTA) MR imaging.
A sharp trigeminal-pontine angle was observed in 25 patients (25/30) on the affected side. As such, the mean angle of the trigeminal nerve on the affected side (40.17) was significantly smaller than that on the unaffected side (48.91, p = 0.001) and that in the control group (52.02, p < 0.001).
A sharp trigeminal-pontine angle on the affected side was found in idiopathic TN patients by FIESTA imaging. This suggests that a sharp trigeminal-pontine angle increases the chance of neurovascular compression on the medial side of the trigeminal nerve.

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    ABSTRACT: Background: The aim of this prospective study was to evaluate whether the cerebellopontine angle (CPA) cistern area and trigeminal nerve cisternal length play a role in the pathogenesis of trigeminal neuralgia (TN). Methods: High-resolution 1.5 T magnetic resonance imaging of the posterior fossa was performed in 26 patients with TN and 18 age-matched healthy controls. Axial T2-weighted, three-dimensional constructive interference in steady-state (3D-CISS) was used to measure bilaterally the cross-sectional area of the CPA cistern and trigeminal nerve cisternal length. Results: In patients, the cross-sectional area of the CPA cistern and trigeminal nerve cisternal length was smaller on the affected side (p = 0.04). Healthy controls tended to have larger cisternal areas and longer trigeminal nerve lengths than patients (p = 0.059, p = 0.071, respectively). Larger CPA cisternal areas tended to be seen in older patients. There was a strong correlation between the cross-sectional area of the CPA cistern and the length of the trigeminal nerve (p = 0.000). Conclusions: Smaller CPA cisterns and short cisternal trigeminal nerves impact the pathogenesis of essential TN by facilitating the neurovascular conflict, especially in younger patients. Trigeminal nerve cisternal measurement provides an easy and direct estimation of the CPA area. This information can be used for surgical planning and potentially for outcome prediction.
    No preview · Article · Dec 2012 · Acta Neurochirurgica
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    ABSTRACT: The aim of this study was to analyze the prognostic factors of trigeminal neuralgia (TN) after microvascular decompression (MVD), and to evaluate the volumetric parameters of the cerebellopontine angle (CPA) cistern as a pathogenic factor and imaging predictor. This retrospective study included 70 patients with primary TN treated with pure MVD, followed up for at least 1 year and evaluated by high-resolution MR imaging. The volume of the CPA cistern was calculated bilaterally, and the "Cistern Deviation Index" was defined to represent degree of deviation of the CPA cistern. Clinical data and volumetric parameters were compared between patients with TN and age- and sex-matched controls without TN, and between the recurrent and non-recurrent patients. The transposition procedure had a better outcome than the interposition procedure (P < 0.001). There was a significant difference in the volume of CPA cistern between the affected and unaffected side (152.1 ± 50.1 vs. 179.9 ± 63.7 mm(3), P < 0.001) in patients with TN, while no significant difference between the right and left side (158.7 ± 44.6 vs. 163.1 ± 49.8 mm(3), P = 0.162) in controls. The Cistern Deviation Index was significantly larger in controls than in patients with TN (P = 0.048), and in the non-recurrent patients than in recurrent patients (P = 0.040). We demonstrated that the volumetric parameters of the CPA cistern are a marker for understanding the pathogenesis of TN and useful for predicting the recurrence after MVD. The Cistern Deviation Index might contribute to deciding the surgical approach.
    No preview · Article · Mar 2014 · Acta Neurochirurgica
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    ABSTRACT: Objectives: The etiology of classic trigeminal neuralgia (CTN) is still under debate and, together with neurovascular compression (NVC), other anatomical abnormalities have been considered, including differences of trigeminal nerve (TN) volume. Design: We evaluated the volumes of affected and non-affected nerves and the presence and type of NVC in large group of 84 CTN subjects prior to gamma knife treatment (GKS) on MR images. Correlation between affected nerve volume and NVC, treatment outcome and demographic characteristics were explored. Results: NVC was detected in 71% of affected nerves, 52% of non-affected nerves, and in 31% of subjects bilaterally. Lower trigeminal nerve volume was detected on the affected side (p<0.001, affected mean 34.9 mm3 ± 14.4 SD, non-affected mean 41.9 mm3 ± 17.7 SD), however, no correlation between affected nerve volume and the presence and type NVC, treatment outcome or demographic data was detected. Conclusion: Our results suggest that NVC may trigger CTN in susceptible subjects but is not a reliable disease marker. Lower trigeminal nerve volume appears to manifest independently of NVC, and may represent nerve asymmetry rather than atrophy. No correlation between volumetry and clinical data was detected including treatment outcome after GKS.
    No preview · Article · Jul 2014 · Neuro endocrinology letters
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