Endoscopic Endonasal Approach for Clival Chordomas: 12 Years of Experience from a Large Skull Base Referral Center

Background: Endoscopic Endonasal Approaches (EEAs) have become a primary option for many skull base surgeons for treating clival chordomas. The experience with these approaches is still growing.

Methods: We evaluated our institutional experience with 151 EEAs performed on 106 patients with clival chordomas over the past 12 years (4/2003 to 1/2015). Sixteen patients also underwent open procedures. We retrospectively reviewed relevant clinical and radiographic information. The Cox proportional hazards model, Pearson correlation coefficient, logistic regression, Chi-square, and Fisher exact tests were utilized as appropriate (SPSS 21, IBM Corp).

Results: Average age at the time of surgery was 44 years (4–88), with 64% male. Average pre-operative tumor volume was 25cc (1–202cc), 28% of patients were neurologically intact, and 84/151 (56%) surgeries were performed for recurrence. The overall gross total resection (GTR) rate in our cohort was 65%. Our GTR rate was 75% for primary tumors, and 53% for recurrent tumors (OR=0.38, p = 0.016). Multiple (>1) prior surgeries were strongly associated with decreased GTRs (OR=0.13, p < 0.001), and so was the involvement of the craniocervical junction (OR=0.24, p = 0.01), the involvement of the lower 3rd of the clivus (OR=0.32, p = 0.012), and lateral extension of the tumors (OR=0.37, p = 0.05). Remarkably, the presenting tumor volume, intradural extension, and symptomatic presentation were not significantly associated with decreased GTR rates in our study. Overall, 88% received adjuvant radiation (82% for GTRs, and 94% for non-GTRs). In our series, 0.48% experienced a clinical deterioration after surgery, whereas 47% experienced clinical improvement. Overall, 44/151 (29%) tumors recurred during an average of 39 (8–137) months of follow-up. Average progression-free survival (PFS) was 20 months (1-year PFS=81%, 5 -year PFS=57%). Complete resections were associated with a decreased overall risk of recurrence and longer PFS (HR 0.34, p < 0.001). Interestingly, this association persisted when evaluating only the patients who received adjuvant radiotherapy (HR=0.29, p = 0.003). Nineteen patients died during follow-up (average survival from tumor diagnosis= 6.4 years; range=5.2–102 months post-operatively). Multiple prior surgeries were the main risk factor for clinical deterioration (OR=5.9, p = 0.016). Cerebrospinal fluid (CSF) leaks remained the main source of morbidity with an overall incidence of 22%. Notably, males were at a significantly higher risk for CSF leaks (OR=4.7, p = 0.001). The years of experience had a strong correlation with the rates of GTRs (r=0.199, p = 0.034). This correlation persisted even when evaluating only recurrent tumors (r=0.414, p = 0.003). Experience, however, has had no statistically significant correlation with the incidence of CSF leaks.

Conclusion: The EEA affords high rates of GTR, and low rates of cranial-nerve deficits. There is, however, a significant learning curve with these approaches, which translates into higher rates of GTRs. The main limitations of EEA are the craniocervical junction and significant lateral extension. CSF leaks remain a main cause of morbidity, for which males may be at greater risk.