Post-embolization neurological syndrome after embolization for intracranial and skull base tumors: transient exacerbation of neurological symptoms with inflammatory responses

Pre-operative embolization is an effective treatment strategy for hypervascular intracranial and skull base tumors. However, neurological complications resulting from tumor swelling, cranial nerve ischemia, or hemorrhage can occur after embolization. The purpose of this study was to examine the relationship between neurological complications following pre-operative embolization and minor adverse events including fever, headache, or increasing inflammation, which are common after embolization for abdominal tumors (i.e., post-embolization syndrome, PES). We retrospectively reviewed 39 consecutive patients with pre-operative embolization for intracranial and skull base tumors. Neurological symptoms and minor adverse events were regularly observed after embolization. The degree of devascularization was evaluated using enhanced magnetic resonance imaging. We also evaluated changes in peritumoral edema. Neurological complications occurred in eight cases, five of whom had exacerbation of existing neurological symptoms, which occurred concurrent with a general inflammatory response. We termed this clinical condition post-embolization neurological syndrome (PENS). The mean time to neurological symptom onset was 37.2 h after embolization. PENS was self-limiting in all cases but one, which required emergency surgery. The remaining three cases were diagnosed with cranial nerve ischemia. PENS is an important neurological complication after pre-operative embolization, which should be distinguished from ischemic or hemorrhagic complications. PES is a minor complication with favorable prognosis, whereas PENS should be considered as a dangerous clinical sign that may require emergency treatment. Further experiments are needed to elucidate the pathology of PENS.