Abstract
BackgroundSkull base chordomas (SBCs) are rare malignant bone tumors with dismal long-term local control. Endoscopic endonasal surgeries (EESs) are increasingly adopted to resect SBCs recently. Gross total resection (GTR) favors good outcomes. However, the SBCs often invade the skull base extensively and hide behind vital neurovascular structures; the tumors were challenging to remove entirely. To improve the GTR, we established a surgical strategy for EES according to the tumor growth directions.MethodsA total of 112 patients with SBCs from 2018 to 2019 were classified into the derivation group. We retrospectively analyzed their radiologic images and operation videos to find the accurate tumor locations. By doing so, we confirmed the tumor growth directions and established a surgical strategy. Fifty-five patients who were operated on in 2020 were regarded as the validation group, and we performed their operations following the surgical strategy to verify its value.ResultsIn the derivation group, 78.6% of SBCs invade the dorsum sellae and posterior clinoid process region. 62.5% and 69.6% of tumors extend to the left and right posterior spaces of cavernous ICA, respectively. 59.8% and 61.6% of tumors extend to the left and right posterior spaces of paraclival and lacerum ICA (pc-la ICA), respectively. 30.4% and 28.6% of tumors extended along the left and right petroclival fissures that extend toward the jugular foramen, respectively. 30.4% of tumors involved the foramen magnum and craniocervical junction region. The GTR was achieved in 60.8% of patients with primary SBCs in the derivation group. Based on the tumors’ growth pattern, pituitary transposition and posterior clinoidectomy techniques were adopted to resect tumors that hid behind cavernous ICA. Paraclival ICA transposition was used when the tumor invaded the posterior spaces of pc-la ICA. Lacerum fibrocartilage resection and eustachian tube transposition may be warranted to resect the tumors that extended to the jugular foramen. GTR was achieved in 75.0% of patients with primary SBCs in the validation group.ConclusionBesides the midline clival region, the SBCs frequently grow into the eight spaces mentioned above. The surgical strategy based on the growth pattern contributes to increasing the GTR rate.
Highlights
Skull base chordomas (SBCs) are traditionally considered to be histologically low-grade bony neoplasms
Combined with literature reports on the location of chordoma [2, 6, 7], endoscopic anatomy [8], and our group’s experience in the endoscopic endonasal surgery (EES) treatment of chordoma [9], we found that chordoma has the characteristics of extending along the skull base sutures (Figure 1)
Besides the central part of chordoma often located in the midline region of the clivus, the most commonly involved areas include the following eight spaces: dorsum sellae and posterior clinoid process (DS-PCP), bilateral posterior spaces of cavernous ICA, bilateral posterior spaces of paraclival and lacerum ICA, bilateral petroclival fissure spaces that extend toward the medial part of the jugular foramen, and foramen magnum and craniocervical junction (FM-CCJ)
Summary
Skull base chordomas (SBCs) are traditionally considered to be histologically low-grade bony neoplasms. Many advances have been achieved in medical treatment in recent years, and some drugs have shown effectiveness, but the overall response rate is still low in SBCs. Long-term survival and favorable neurological outcome continue to be challenging. The resection rate seems improved with new equipment and endoscopic endonasal surgery (EES), the radical resection rate was still challenging for SBCs. Chordomas arising from the clivus are among the most challenging neoplasms for skull base surgeons [6]. Skull base chordomas (SBCs) are rare malignant bone tumors with dismal long-term local control. Endoscopic endonasal surgeries (EESs) are increasingly adopted to resect SBCs recently. To improve the GTR, we established a surgical strategy for EES according to the tumor growth directions
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