Vascular Compression in Trigeminal Neuralgia Discloses Trigeminal Root Somatotopic Organization
Gianfranco De Stefano1, Daniel Litewczuk1, Emanuele Ripiccini3, Giuseppe Di Pietro2, Pietro Falco2, Eleonora Galosi1, Caterina Leone1, Andrea Truini1, Giulia Di Stefano2
1Department of Human Neuroscience, Sapienza University of Rome, 2Sapienza University of Rome, 3Advanced Quantum Architecture Laboratory, Swiss Federal Institute of Technology of Lausanne
Objective:
In this combined clinical, neuroimaging and neurophysiological study we aim to explain classical trigeminal neuralgia symptoms and neurophysiological responses through the disclosure of trigeminal root somatotopic organization.
Background:
In Trigeminal Neuralgia (TN) pain is localized in the distribution of one or more branches of the trigeminal nerve. A hallmark of TN is the presence of discrete skin areas able to trigger pain attacks when touched. In classical TN trigeminal reflexes are normal but dedicated MRI studies can recognize a vascular compression with morphological changes of trigeminal root.
Design/Methods:
We enrolled 53 patients with a definite diagnosis of classical TN. From MRI images we measured the polar coordinates of the impacting vessel on the trigeminal root circumference and then correlate it with pain distribution, trigger zones and latencies of the early components of the trigeminal reflexes.
Results:
Pain in V1, V2 and V3 is associated, respectively, with vascular compression in the medial, superior and lateral aspect of the nerve (p<0.05). Cutaneous trigger zones are associated with corresponding region of the circumference (p<0.05). Side asymmetry in the latency of the R1 component of the blink reflex is associated with superomedial compression, while side asymmetry in the latency of the SP1 component of the masseter inhibitory reflex is associated with superior compression when the reflex is evoked from the infraorbital nerve, and with lateral compression when it is evoked from the mental nerve (p<0.05).
Conclusions:
In TN, pain distribution, trigger zones and increased latencies of trigeminal reflexes are correlated with specific sites of neurovascular compression along trigeminal root circumference, disclosing its somatotopic organization.
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