Essential trigeminal neuralgia is the most common facial pain. In forms resistant to drug and disabling treatments, surgical treatment may be offered to the patient. The type of intervention will be conditioned by the presence or absence of a vasculo-nervous conflict objectified by MRI(Magnetic resonance imaging) Morphological MRI with contrast injection does not always allow an accurate assessment of trigeminal nerve damage in patients with essential facial neuralgia. Despite advances in the anatomical definition of high-resolution MRI, the correlation between a vascular conflict visible on MRI and present during surgery and prolonged postoperative clinical improvement remains insufficient These data raise the question of additional imaging sequences to assess the distressing characteristics of NT in addition to the usual anatomical criteria for compression By performing during morphological MRI two additional sequences, one in diffusion tensor (DTI) and one in resting state (fMRI), we could better characterize the achievement of NT The contribution of new imaging sequences in the context of essential trigeminal neuralgia treated with microvascular decompression (MVD) would: 1/improve the diagnostic criteria for suffering and compression of the NT (trigeminal nerve) 2 / define objective prognostic criteria for the effectiveness of surgery, particularly in the context of unusual clinical symptoms or moderate conflict on MRI (Magnetic resonance imaging) 3 / to analyze more precisely the causes of recurrence at a distance from surgery and help in the decision of re-intervention Our main hypothesis: the addition of a diffusion tensor sequence and sequences (allowing functional brain analysis) in addition to standard anatomical MRI in the assessment of a vasculo-nervous conflict would allow us to better characterize involvement of the trigeminal nerve in essential facial neuralgia. It also helps guide therapeutic management and surgical indications. This is a prospective, monocentric cohort study. It will be offered to patients referred to neurosurgery or to the pain assessment and treatment center for assessment and management of a neuralgia of the essential trijumeau unilateral.