Trigeminal neuralgia diagnosis
The diagnosis of trigeminal neuralgia is clinical, but high-quality imaging is mandatory to identify secondary causes and a neurovascular contact. New methods such as DTI (diffusion tensor imaging) allow a more differentiated assessment of the consequences of a vascular contact on the trigeminal nerve 1).
Reinard et al., from the Department of Neurosurgery, Henry Ford Medical Group (HFMG), and the Wayne State University School of Medicine, Detroit, Michigan, identify racial and socioeconomic disparities in the diagnosis and treatment of trigeminal neuralgia (TN), this appeared to stem from outside HFMG from a difference in referral patterns to the neurologists and neurosurgeons 2).
The diagnosis of trigeminal neuralgia is based on patient's history, and an imaging study is usually indicated when there are clinical signs suggestive of this. Imaging can help diagnose other causes such as multiple sclerosis and tumors. CT is limited in evaluating the brainstem and cisterns. MRI is the imaging modality of choice and should be considered the initial screening procedure in the assessment of patients with trigeminal neuralgia 3).
MRI
Vascular contact deforming the trigeminal nerve is seen in about 15% of cases. In such cases, it is important to mention if the contacting vessel is an artery or vein and if it is contacting the proximal or distal portion of the cisternal portion of the trigeminal nerve. A dedicated protocol including T2 or T1 volumetric acquisition techniques with thin slices in all three planes should be helpful. However, an evidence-based review did not find evidence to support or refute the usefulness of MRI for this purpose 4).
Trigeminal Neuralgia can be a typical symptom in cerebellopontine angle tumours like epidermoid, especially in young patients, so all the patients with trigeminal neuralgia should be investigated for lesion in cerebellopontine region 5).
Magnetic resonance imaging (MRI) can be helpful in visualizing neurovascular conflict (NVC) of the trigeminal nerve, but the relationship between these two events is controversial.