Polymethyl Methacrylate Cranioplasty Is an Effective Ultrasound Window to Explore Intracranial Structures: Preliminary Experience and Future Perspectives

Objective To evaluate the feasibility of transcranial sonography in patients harboring polymethylmethacrylate cranioplasties (PMMA-CP) and explore whether this material is a valid sonic window to explore intracerebral structures. Methods In 6 patients, we performed transcranial sonography (TCS), using the PMMA-CP as sonic window. To test the reliability of ultrasound images, we collected several quantitative and qualitative measurements of intracranial structures and compared these sonographic images with standard computed tomography (CT) scan images. Results We found that PMMA-CP is a very good sonic window and allowed us to obtain very good quality echographic images of intracranial structures, as shown by the comparison of measurements with CT scan, which were very reliable. The main drawback was related to the shape (i.e., the curvature) of the cranial flap, which hindered the ultrasound probe from correctly adhering to the scalp. Conclusions Although limited by the restricted number of cases, this preliminary experience represents the first available data about the serial use of TCS using PMMA-CP as window. These results open the path to the routine use of TCS to longitudinally control patients already harboring PMMA-CP. More, we here discuss its potential role in globally reducing the number of follow-up CT and magnetic resonance imaging scans required in different type of patients and pathologies.