Giant Posterior Communicating Artery Aneurysm Presenting as Trigeminal Neuralgia.

Background We report an extremely rare case of trigeminal neuralgia (TN) caused by a giant posterior communicating artery aneurysm. Methods We describe the case of a 73-year-old man who suffered disabling TN, which was deeply exacerbated when he laid down. Computed tomography angiography and digital angiography revealed an unruptured giant posterior left communicating artery aneurysm projecting to the posterior fossa and contacting the trigeminal root. Results The size and projection of the aneurysm seemed responsible for both the neuralgia itself and its peculiar clinical characteristic of exacerbation when the patient laid down. The aneurysm was surgically clipped, then opened and emptied to decompress the trigeminal root. The patient reported an immediate complete remission of the neuralgia. Conclusion The finding of TN secondary to aneurysms is rare but even more in the case of a posterior communicating aneurysm. The clinical clue that should alert physicians about the presence of an aneurysm as the cause of TN is exacerbation of pain by adopting a supine position. Due to the high risk of rupture associated with giant and symptomatic aneurysms, we believe that treatment should be aggressive in this case, not only to solve the symptomatic TN but also to avoid the risk of aneurysm rupture in the future. The treatment selection between surgical clipping or endovascular coiling with or without stenting, depends on patient's clinical condition and the size and shape of the aneurysm.