Introduction Posterior communicating artery (PCoA) is an unusual location for dissecting aneurysms (DAs). To the best of our knowledge DA and coiling of a perforating branch of PCoA have never been described.

Aim of Study Report of unusual clinical presentation, evolution and endovascular treatment of a symptomatic DA of a perforating PcoA branch.

Methods A patient in their 50s presented with sudden headache, diplopia and right ophthalmoplegia is reported. Computed-tomography (CT) was negative for intracranial haemorrhage (IH) and CT-angiography (CTA) showed a saccular aneurysm in right PCoA region. Before digital subtraction angiography (DSA) patient developed sudden dysarthria and left hemiparesis. CT scan was negative for IH. DSA did not reveal any aneurysm. Magnetic Resonance (MR) detected a recent ischemic lesion in the right anterior thalamus compressing internal capsule and a thrombosed aneurysm sac in the PCoA region, suggestive for DA. Patient was followed-up with CT and CTA on day 3 and 11 revealing its progressive recanalization. On day 15 patient underwent a new DSA which showed that the DA belonged to a perforating branch of PcoA; DA was occluded with a detachable coil.

Results Patient recovered well and 18-month follow-up DSA revealed stable occlusion of the DA.

Conclusion DAs can occur anywhere, even in perforating arteries arising from PCoA. Clinical presentation and evolution may be unpredictable; close monitoring is advised, especially if the clinical course is fluctuating. Sac thrombosis might occur and can be therapeutic; recanalization needs early and definitive treatment. Coiling can be a safe and effective therapeutic option.

Disclosure of Interest Nothing to disclose.