Initial Management of Notochordal Injuries at the Skull Base: An Integrative Review

Abstract Notochordal tumors include benign notochordal cell tumors (BNCTs) and chordomas, which are aggressive bone tumors derived from remnants of the notochord. When they affect the skull base, they usually occur in the clivus region. The treatment includes resection and high-dose radiotherapy. A benign notochordal remnant, BNCT is generally found incidentally, and it commonly appears in the clival region, and it does not require initial resection or radiotherapy. On imaging studies, the differentiation of low-grade chordomas and BNCT is a challenge, as these lesions can coexist and overlap, which interferes with the management decision for these patients. To evaluate the safety of initial monitoring of seemingly-benign notochordal lesions with atypical radiological features suggestive of developing chordomas, as reported in the literature. The current study is an integrative review based on articles selected from the PubMed/MEDLINE and Science Direct databases. A total of 131 articles were found, but 113 were excluded, and 16 articles were found in both databases and were considered only once in the present study. Thus, the review included 18 articles. The literature analysis highlighted radiological characteristics and clinical aspects as influencing factors in the initial management of injuries. On magnetic resonance imaging (MRI) scans, the lesions present hypointensity on T1-weighted and hyperintensity on T2-weighted images, and benign lesions generally do not enhance with gadolinium. In some cases, possibly-indolent lesions present atypical patterns, such as bone erosion and minimal or moderate enhancement. The overlap between benign notochordal tumors and chordomas has been investigated, and there are still issues regarding safety in terms of the decision to follow-up seemingly-benign lesions with some atypia on the radiological evaluation. The literature recommends initial surveillance of these lesions, indicating a certain level of safety if they do not accompany symptoms and the radiological characteristics suggestive of malignancy are minimal. Furthermore, follow-up must be long-term, with examinations approximately 15 and 36 months later, as more indolent forms of chordoma can take a few years to transform into larger lesions. The consensus on the monitoring of patients with atypical incidental lesions of benign appearance is not well established. However, the literature suggests that, initially, lesions presenting one or two radiological features suggestive of early-stage chordoma can be safely monitored. Nevertheless, more studies, especially longitudinal ones, are essential to meet the need for concrete resolution on this subject.