Imaging-guided radiofrequency ablation of osteoid osteoma in typical and atypical sites: Long term follow up.

PURPOSE: To assess efficacy and safety of imaging-guided radiofrequency ablation (RFA) of Osteoid Osteoma (OO) in both typical and atypical sites. METHODS AND MATERIALS: Between January 2014 and March 2019, 102 consecutive percutaneous RFA were performed and retrospectively reviewed. The procedures were performed using a RFA bipolar ablation system (Covidien, exposed tip of 0.7-1cm), under Computed Tomography (CT) guidance or using a navigation system (Masmec) under CT and Cone Beam CT (CBCT) guidance. Patients were followed up over 24 months. Clinical success and recurrences were considered on the base of established criteria. In patients with clinical failure and/or imaging evidence of relapse, retreatment was considered. RESULTS: Administered power per-procedure was ≤8 W (mean temperature, 90°C). The pre-procedure average value of visual analog scale (VAS) was 8.33+/-0.91. Primary and secondary success rate 96.08% (98/102) and100% (102/102), respectively. No major complication was described. Technical success was proved in every patient by CT scan acquisition after needle positioning. Relapse and tumour location were significantly correlated (p-value = 0.0165). The mean dose-length product was 751.55 mGycm2. Advanced bone healing was noted in 68 lesions after 1y-follow up and in 86 lesions after 2y-follow up. CONCLUSION: Imaging-guided percutaneous RFA is a highly effective technique for OO, both in typical and atypical sites. CT or CBCT guidance, navigation systems and operator experience grant the technical success, which is the most crucial parameter affecting outcome.

Hyperacute reversible encephalopathy related to cytokine storm following COVID-19 vaccine.

We describe the first case of hyperacute reversible encephalopathy following COVID-19 vaccination. A patient presented with acute onset encephalopathy, mainly characterized by agitation and confusion, rapidly responsive to high dosage steroid therapy and complete remission within 3 days from onset. The clinical manifestation was related with systemic and CSF cytokine hyperproduction, responsive to steroid therapy. Although the occurrence of encephalopathy after vaccination may be just a casual temporal association, we speculate that the cytokine-storm could be the result of an excessive innate immune response against the vaccine, in a predisposed patient susceptible to autoimmunity.