A Magnetic Resonance Study and Demonstration of the Spectrum of Diverse Aetiologies for Trigeminal Neuralgia

Abstract

Introduction: Intractable hemifacial pain or twitching can be an incapacitating disorder caused by trigeminal neuralgia. The aetiologies for trigeminal neuralgia are numerous and the most frequent cause is a neurovascular compression. However, there are other less common aetiologies which need to be assessed. Magnetic Resonance Imaging (MRI) with dedicated cranial nerve sequences remains the modality of choice in diagnosing and establishing a cause for this condition. Aim: This study aims in showing that all trigeminal neuralgias are not secondary to neurovascular compression and other unusual causes needs to be looked for and assessed during an MRI examination. Materials and Methods: This was a cross-sectional observational study conducted at the Saveetha Medical College and Hospital, Chennai, India (from September 2015 to August 2017). This study included 70 patients presenting with clinical symptoms of unilateral trigeminal neuralgia. The MRI was done using a 1.5 Tesla, Philips multiva system. A high resolution 3D T2 DRIVE or 3D bFFE cranial nerve sequences were performed in addition to the routine Magnetic Resonance (MR) sequences. Patients with known dental issues which could cause the pain, and patients with intracranial tumours were excluded from the study. Results: Out of the 70 patients, we found that the majority (53) had a neurovascular compression, which ranged from a simple indentation by a tortuous Superior Cerebellar Artery (SCA) to full blown vertebrobasilar dolichoectasia. Out of the remaining cases, six were found to be secondary to benign intracranial hypertension with prominent Meckel’s caves. There were two cases who had an unusual finding of “Trigeminal pontine sign”, which were post infective (postherpetic being the most probable cause). Conclusion: By tailoring the MRI protocol in present study, and based on the clinical presentation, we can conclude that in most cases of clinically diagnosed trigeminal neuralgia, it could be possible to demonstrate a probable cause and consequently aid the clinician for appropriate management, and to select only the deserving cases for microvascular decompression.

Keywords

• herpetic neuralgia
• microvascular decompression
• neurovascular compression
• trigeminal pontine sign