Trigeminal neuralgia is divided into primary and secondary types. Primary trigeminal neuralgia refers to cases where no specific cause is apparent. However, with the advancement of modern medicine, doctors have discovered that there is actually a cause for primary trigeminal neuralgia. It is due to the lack of protective myelin sheath over the initial segment of the trigeminal nerve, which gets irritated by the pulsation of nearby small arteries. In such cases, further investigations like brain MRI and cerebral angiography can usually identify the responsible blood vessel. On the other hand, secondary trigeminal neuralgia occurs along with corresponding tumors and inflammation during the progression of the neuralgia, and MRI can assist in diagnosis.