Investigations
1st investigations to order
no first test
Test
Result
diagnosis is usually clinical
Investigations to consider
MRI
Test
Not necessary for clinical diagnosis of classical trigeminal neuralgia. Necessary if secondary trigeminal neuralgia is suspected. Some guidelines recommend that magnetic resonance imaging (MRI) should be performed for all patients; no clinical characteristic can reliably exclude secondary TN.[20][21][22]
Should always be performed prior to surgery or other procedural therapeutic maneuvers to exclude secondary causes. MRI of the head without and with IV contrast or MRI of the orbits, face and neck without and with IV contrast are appropriate for the initial imaging of patients with trigeminal neuralgia; they may be used as equivalent alternatives or as complementary procedures.[21] 3D heavily T2-weighted MRI sequences, magnetic resonance angiography (MRA), and a combination of the two can be used to determine the anatomy of the vascular loops that may be compressing the trigeminal nerve.[21][23]
Result
may demonstrate presence of abnormal vessel loop in association with the trigeminal nerve, presence of other pathologies (e.g., tumour, infarct, multiple sclerosis plaque)
trigeminal reflex testing
intra-oral x-ray
Test
Only required if dental cause of pain suspected. May demonstrate dental caries, dental fracture, osteomyelitis.
Result
no dental cause of pain demonstrated
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