Long-Term Outcomes following Surgical Resection of Skull Base Esthesioneuroblastomas

Introduction: Esthesioneuroblastoma is a difficult disease for the skull base surgeon to treat. Not only does the combination of complex local anatomy, frequent late stage diagnosis, and involvement of critical neurovascular structures present a significant technical challenge, but the possibility of recurrence even decades after onset makes clinical follow-up as important as initial complete surgical extirpation. Fortunately, with the advent of endoscopic tools to supplement existing transcranial and transfacial approaches alongside advances in image guidance technology, more complete resections can be performed with less morbidity to our patients than at any time in the past. Because of the rarity of the tumor, however, long-term evidence about patient outcomes from such approaches is lacking in the literature.

Methods/Materials: We present our single institution experience in combined otolaryngology/neurosurgical resections of esthesioneuroblastoma over the span of the past 24 years from with all but six cases involving two senior surgeons at our program. A total of 44 patients underwent surgical resection of esthesioneuroblastoma; of these, 38 had adequate information for this review.

Endoscopic techniques were combined with transcranial/transfacial resection in all the patients. Closure of the resulting skull base defect was accomplished with abdominal fat grafts, middle turbinate flaps, and/or nasal septal flaps along with fibrinogen glue to create watertight closure of the skull base defect.

Results: As the typical tumor location precludes, large marginal resection without significant functional deficits, postoperative radiation is a key tenet of our treatment. Overall, 79% did receive postoperative radiation, with 60% of those starting treatment within 2 months of surgery.

Mean follow-up of the patient group was 81 months. Patients lost to clinical follow-up were contacted through online SSDI databases. When patients treated in the past 24 months were excluded, the average follow-up for this subgroup (n= 27) jumps to 102.4 months (8.5years).

Overall, 71% are NED. Thirteen patients (34%) developed metastatic (n= 6) or recurrent disease (n= 7), most succumbing to complications secondary to this. One patient continues to be NED following excision of submandibular gland recurrence over 10 years following the initial resection, now 3 years out. There appeared to be a correlation between late radiation treatment and metastasis, as delays over 10 weeks were associated with a 50% metastasis rate, while there were no reported metastases in the group of patients who received radiation within 10 weeks of surgery. There were no intraoperative or immediate postoperative mortalities. While some patients had minimal CSF leakage in the immediate postoperative period, none persisted.

Conclusion: Management of esthesioneuroblastoma continues to be a difficult endeavor. As expected, metastasis or local recurrence after initial resection is a poor long-term prognostic factor and can present over a decade after treatment. This may be associated with delayed onset of adjuvant radiation therapy. Advances in minimally invasive surgical resection with endoscopic techniques may allow for fewer postoperative complications, more complete resection and quicker time to radiation, with potentially less metastatic potential. Continued long-term follow-up of this patient cohort is needed.