Neurophysiological Identification of Cranial Nerves During Endoscopic Endonasal Surgery of Skull Base Tumors: Pilot Study Technical Report.

INTRODUCTION: Intraoperative identification of cranial nerves is crucial for safe surgery of skull base tumors. Currently, only a small number of published papers describe the technique of trigger electromyography (t-EMG) in endoscopic endonasal removal of such tumors. OBJECTIVE: To assess the effectiveness of t-EMG in preventing intraoperative cranial nerve damage in endoscopic endonasal surgery of skull base tumors. MATERIALS AND METHODS: Nine patients were operated on using the endoscopic endonasal approach within a 1-year period. The tumors included large skull base chordomas and trigeminal neurinomas localized in the cavernous sinus. During the surgical process, cranial nerve identification was carried out using monopolar and bipolar t-EMG methods. Assessment of cranial nerve functional activity was conducted both before and after tumor removal. RESULTS: We mapped 17 nerves in 9 patients. Third, fifth, and sixth cranial nerves were identified intraoperatively. There were no cases of postoperative functional impairment of the mapped cranial nerves. In one case we were unable to get an intraoperative response from the fourth cranial nerve and observed its postoperative transient plegia (the function was normal before surgery). CONCLUSION: t-EMG allows surgeons to control the safety of cranial nerves both during and after skull base tumor removal.

Surgical Treatment of Skull Base Tumors, Extending to Craniovertebral Junction.

OBJECTIVE: To conduct a comparative analysis of 2 groups of patients with skull base chordomas extending onto the craniovertebral junction, who underwent surgical treatment using extracranial approaches with and without craniocervical fusion. METHODS: The study group included 29 patients with skull base chordomas, extending to the craniovertebral junction, who were operated on from 2000 to 2015. The patients underwent the following surgical treatment: posterior craniocervical fusion followed by tumor removal using transoral and combined transoral and transnasal approaches. The reference group included 21 patients with the same disease, who underwent tumor removal surgery using the transoral approach without craniocervical fusion. RESULTS: In the study group, in 27.5% of all cases (8 patients), the tumors were removed radically; in 65.5% of all cases (19 patients), the tumors were removed subtotally; and in 7% of all cases (2 patients), the tumors were removed partially. In the reference group, the extent of surgical radicality was as follows: radical, 0%; subtotal, 19% (4 cases); partial, 81% (17 cases). CONCLUSIONS: Use of the proposed surgical technique in clinical practice may help increase the radicality of tumor excisions, decrease the number of postoperative complications, accelerate the rehabilitation process, and increase the quality of life in patients with skull base tumors extending to the craniovertebral junction.