Supplementary Material for: Tailoring the surgical approach to Chiari I malformation with Intraoperative Ultrasounds: Advantages, limitations, and controversies

Introduction Decompression of posterior cranial fossa remains the mainstay of surgical treatment of Chiari Malformation type I (CMI), though several surgical manoeuvres have been differently combined to bony decompression aiming to increase the efficacy of surgery. In this context, Intraoperative Ultrasounds (IOUS) claims to offer a real-time feedback of adequacy of surgical decompression, thus accordingly tailoring the aggressiveness of surgery. The present review aims to highlighting benefits, limitations, and areas in need of further investigation.
Materials and Methods A comprehensive literature search of PubMed, Scopus, and Google Scholar was performed for studies published in English in the last 30 years. The following keywords - including MeSH terms - were used to retrieve eligible papers: “Chiari Malformation Type I”, “posterior fossa decompression”, “ultrasonography”.
Results A total of 3189 results was collected. Duplicate records were then removed (n=1591). A total of 1598 papers were screened, and 1531 records were excluded through title and abstract screening; 65 studies were considered relevant to our research question and were assessed for eligibility. Finally 23 articles were included in the review.
Conclusions IOUS has been frequently used to evaluate the adequacy of surgical decompression, though this qualitative assessment remains subjective with obvious inter-operator variability. On the other side, a quantitative assessment has been more rarely used through the literature, as this approach is difficult to reproduce. Despite the obvious advantages of IOUS, further investigation is required to standardize this approach.