Neuroimaging in trigeminal neuralgia

Abstract

Trigeminal neuralgia is a debilitating craniofacial pain disorder characterized by recurrent, unilateral, electric shock-like facial pain. Magnetic resonance imaging plays a central role in the evaluation of patients with suspected trigeminal neuralgia by identifying clinically significant neurovascular compression, demonstrating morphological changes of the trigeminal nerve, and excluding secondary causes. This review provides an overview of the relevant anatomy of the trigeminal nerve and its transition zone and discusses imaging features that help distinguish symptomatic neurovascular conflict from incidental vascular contact. Particular emphasis is placed on high-resolution three-dimensional heavily T2-weighted sequences for visualization of the cisternal trigeminal nerve and its relationship with adjacent vessels, as well as three-dimensional time-of-flight magnetic resonance angiography and contrast-enhanced three-dimensional T1-weighted imaging for vascular characterization. The imaging spectrum of secondary trigeminal neuralgia, including tumors, demyelinating disease, vascular malformations, inflammatory conditions, and infectious disorders, is also reviewed. Advanced techniques, including diffusion tensor imaging and quantitative assessment of trigeminal nerve morphology, may provide additional information regarding microstructural abnormalities and treatment response. Vendor-specific three-dimensional sequences, including constructive interference in steady state, fast imaging employing steady-state acquisition, sampling perfection with application-optimized contrasts using different flip-angle evolutions, volume isotropic turbo spin-echo acquisition, and three-dimensional variable-flip-angle fast spin-echo imaging, are discussed along with their practical advantages and limitations. Post-treatment imaging following microvascular decompression and stereotactic radiosurgery is also addressed. A systematic high-resolution magnetic resonance imaging approach can improve diagnostic confidence, facilitate treatment planning, and aid assessment of postoperative or recurrent symptoms.