Abstract
Purpose: Is to evaluate the accuracy of fused 3D time-of-flight (TOF) MR angiography and 3D Steady-State sequence (FIESTA) versus 3D contrast-enhanced T1 weighted images in evaluation of neurovascular compression via an inter-observer agreement protocol. Methods: Patients presented with trigeminal neuralgia, tinnitus, or facial hemispasm were examined using 3D-TOF-MRA, 3D-FIESTA, and 3D contrast-enhanced T1WI of the cerebellopontine angle to assess neurovascular compression. Two independent readers assessed the location, signal alteration, offending vascular structure, and grade of neurovascular compression using fused 3D-TOF-MRA and 3D-FIESTA versus contrast-enhanced T1 weighted images. The Kappa test for interobserver agreement was done. Results: The final study cohort consisted of 56 patients (42 females and 14 males) with a mean age of 38.25 ± 1.94. AICA was the offending vessel for 32 (57.1%) patients. The most common offending nerve was the trigeminal nerve in 26 patients, followed by facial/vestibulocochlear complex in 18 patients, and solely the 8th nerve in 12 patients. All three grades of compression were encountered in this study with percentages of 48.2% (27/56), 30.3% (17/56), and 21.4% (12/56) for grades I, II, III respectively. Fused TOF and steady-state images, and contrast-enhanced images showed perfect agreement for detection of the side of compression, the relation between nerve and vascular loop, offended neural segment, and offending vessel, while showing good agreement regarding the degree of compression. Conclusion: Fused TOF and steady-state images provide sufficient data to diagnose and grade microvascular compression syndromes comparable to contrast-enhanced images.
Highlights
Neurovascular compression syndromes are due to the presence of conflict between a vascular loop and one of the cranial nerves at the root entry/exit zone in the cerebellopontine angle
Patients presented with trigeminal neuralgia, tinnitus, or facial hemispasm were examined using 3D-TOF-MRA, 3D-FIESTA, and 3D contrast-enhanced T1WI of the cerebellopontine angle to assess neurovascular compression
The anatomic proximity of these nerves to the vascular tree correlates the clinical presentation to the expected anatomical abnormality as classified by Rhoton’s neurovascular bundles [2]; trigeminal nerve is related to and commonly compressed by the superior cerebellar artery, while facial and vestibulocochlear nerves are related to the anterior inferior cerebellar artery
Summary
Neurovascular compression syndromes are due to the presence of conflict between a vascular loop and one of the cranial nerves at the root entry/exit zone in the cerebellopontine angle. Hemifacial spasm was first described in the literature in 1875 in a case of vertebral artery aneurysm compressing the facial nerve, while the concept of neurovascular compression, as per current concept, was first described by Mckenzie in 1936 and more investigated and pioneered by Jannetta [1]. The anatomic proximity of these nerves to the vascular tree correlates the clinical presentation to the expected anatomical abnormality as classified by Rhoton’s neurovascular bundles [2]; trigeminal nerve is related to and commonly compressed by the superior cerebellar artery, while facial and vestibulocochlear nerves are related to the anterior inferior cerebellar artery. Clinical presentation varies according to the severity of compression, symptoms include trigeminal neuralgia, hemifacial spasm, vertigo, tinnitus, and glossopharyngeal neuralgia according to the compressed nerve [1] [3] [4] [5]. MR angiography was applied to visualize abnormal neurovascular proximity [7], while in 2004 Naraghi et al [8] introduced the concept of the constructive interface in steady-state (CISS) where the CSF cisterns are seen hyperintense, visualizing the neurovascular structures accurately in a non-invasive maneuver
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