What is the the cause / causes of trigeminal neuralgia. is it a life long illness?

Sure: Trigeminal neuralgia is caused by vascular compression of the fifth cranial nerve as it exits the brainstem. It may be episodic and is initially treated with certain anti-convulsant medications. If the pain persists or frequently returns, it can be treated with surgery ( micro vascular decompression ) or radiosurgery. There are several other treatment options if the pain persists or returns.

Trigeminal neuralgia: The most common form of paroxysmal orofacial pain is TN. When a demonstrable structural lesion such as a tumor (e.g., meningioma), vascular malformation or demyelinating disease (multiple sclerosis) has been identified, TN is classified as symptomatic. When the cause of TN is unknown, it is classified as idiopathic. See an orofacial pain specialist for diagnosis and management.