Bilateral thalamic stroke after tonsillectomy in a patient with collateral extracranial anastomosis - case report.

Haemorrhage remains the most frequent and serious complication of tonsillectomy. When bleeding is recurrent, gushing, and ceases spontaneously, pseudoaneurysm of the injured artery in the proximity of the tonsillar bed should be suspected. Haemorrhage related to pseudoaneurysm occurs most commonly in the first 30 days after surgery. It can sometimes be excessive and requires a revision procedure such as external carotid artery (ECA) ligation or embolisation. During those procedures, ECA should be checked for possible anastomoses, otherwise the bleeding may persist despite the intervention. We report an unusual case of a patient with recurrent post-tonsillectomy haemorrhage due to pseudoaneurysm of the facial artery, which persisted after ECA ligation because of the presence of collateral occipital-vertebral anastomosis. Due to the recurrence of bleeding episodes, endovascular treatment was implemented. However, the embolisation was complicated by bilateral thalamic stroke with unclear mechanism. This case highlights the importance of anastomosis between ECA and the vertebrobasilar system, both in recurrence of significant post-tonsillectomy bleeding and in potential thromboembolic complications. Therefore, ECA ligation should always be accompanied by exclusion of possible anastomoses. In cases of non-life-threatening bleeding, embolisation seems to be the proper and more selective therapy.